Conference vmszoo::rc

    I too was at the Sudbury drop zone on Saturday. My big excitement
    of the day (Kay Fischer will love this) came while flying my older
    glider. I had just had a few dismal flights off the high start,
    which was continually breaking, so for no discernable reason
    whatsoever,I picked up the glider and hauled back for a hand toss.
    Something I've only done about a hundred times with this plane.
    As I hurled it into the air, I heard this sickening crunch, and
    watched the wings fold neatly in half like a butterfly closing its
    wings. The plane hit the top of its arc and with my hand pulling
    the elevator stick back full, smoothly went into a missle-like dive.
    
    I just stood there dumbfounded. I folded the wings on a HAND TOSS.
    This plane has withstood hard launches into 25 mph wind. The break
    in the wing was relatively clean, and the fuse is only a little
    dinged up. Later analysis showed that this was just waiting to happen.
    The wing joiner wasn't well glued on, and other glue (Ambroid)seemed
    to have lost its strength.
    
    It'll get fixed, and fly again.
    
    Dave
    

Here's a question for you airfoil types:

I'm interested in building a handlaunch glider so I can fly it around the
chopper pad here in front of MRO at lunchtime. I tried to order a Gnome from
Hobby Shack, but they have none in stock. I don't know of any other good HLGs,
so I started thinking about building my own.

The first question that came to mind is what airfoils are proven to be good
for handlauch gliders? I'm assuming a wingspan in the 60" range, with total
wing area around 300-400 sq.in. That gives a chord around 6"-7". I would
build it pretty light, going for light wing loading, and use a built up wing.

Any suggestions?

Dave

    re .57
    All right! Another HLG freak makes an appearance.
    Actually there are quite a few good HLG kits on the market. One
    of the most popular is the Flinger by Larry Jolly. It uses an E-205
    airfoil and is competitive, although you may not be concerned
    with contest work. It sells in the $30-35 range.
    
    If you want to go all out, then the Dodgson Orbiter is hard to beat,
    but very expensive, a la most Dodgson kits, $65.
    I'm getting ready to build one of these to fly at the Nats in July.
    I'll enter a kit and flying review, after I finish my open class
    entry. It uses the S4061 airfoil, with ailerons, and a flap option.
    The S4061 is hard to scratch build because of the under camber.
    For general fooling around on the chopper pad a Clark Y would be
    fine, but the e-205 is just as easy to build.
    
    For top performance, it seems that over 400 sq. in. is best, about
    14 oz., with fairly low aspect ratios. Of course you need a finger
    hole, and it doesn't hurt if your're a weight lifter or x-c skier.
    
    Selig has designed an airfoil for HLG, the S3012 or 3014, but don't
    know of any kits that use it except the Falcon 880 on the outbd.
    ends only.
    
    All the hot sticks are flying foam/glass composite things in HLG
    now, but you don't really need that, yet.
    
    Terry
    

You've obviously got bigger hands than I do ;^)

I've had good luck with Jetco ones like their Thermic series. Their airfoils 
consist of a rounder leading edge and a tapered trailing edge from a flat sheet 
wing of 18-22" span. You want something to throw or a small towline glider?

If you want something to throw and have fun with airfoils with, build/buy a 
boomerang. I got one for my kids at the Science (or was it Children's) Museum 
in Boston and we have a ball throwing it around in a big field we go to. Just
got to be careful that everyone in the area is watching where it goes since it
really can be a weapon. Got to the point where I could actually catch it about 
50% of the time.

        Whoa!
        
        There are hand launched gliders, and then there are hand launched
        gliders. HLGs are free flight solid balsa beasts that date back
        many years. What was refered to in the past couple notes are hand
        launched RC sailplanes, kind of a shrunk down 2 meter ship. These
        are a more recent development of the 80s. Both are discussed back
        in topic 125, although it started on the free flight version.
        Comments about airfoils appropriate for either belong here.
        

Sorry about the confusion. Yeah, I'm talking about an RC type of HLG. I have
experience with both the Clark Y and the E205, and I think I'll print out the
S3012 and 3014 to  see how they compare.
 (Thanks to Mr. Kaplow for putting all
the airfoil files into one convenient spot.) Since I plan to make a built up
wing rather than foam, it has to be a relatively simple airfoil, no under-
camber.

By the way, what's a "finger hole" for? Is that to give your hand a good anchor
when tossing? I had just planned to glue some strips of fine sandpaper to the
sides for grip.

Dave

    re 1113.62, .63
    
    If this is going to be moved I'll jump in now.
    A finger hole is a small box built inside the fuselage, extending
    up far enough to get at least the first finger joint into. It's
    usually placed just behind the wing trailing edge. It's just large
    enough to allow a loose slip fit of the finger, and the forward
    wall is slanted forward slightly with a piece of sandpaper added
    for traction. In other words, you've got a flying bowling ball.
    
    It's the only way to get decent power behind your throws, also the
    plane leaves your hand with power applied at one central point,
    avoiding weaves and swerves.
    
    All this talk about HLG makes me want to repair the Flinger and
    get started on the Orbiter, but first a weight lifting
    program and attendance at an Olympic javelin clinic. ;^)
    
    Terry
    

I'd be interested in finding out more. Sounds like some of the stuff that was 
tried a while ago with R/C boost gliders in the rocketry field. (at least 
weight-wise)

How about getting Ajai involved ;^) I hear he really gets into hand launching...

        re: Hand Launched Sailplane (HLS - solves the duplicate TLA
        problem)
        
        I'm the one who would have mentioned the RC rocket gliders. The
        biggest RCRG as they are called is MUCH smaller than any of the
        HLS I've heard refered to. Ours top out at just over a meter in
        span, and are typically on the order of 2/3 meter span. Glide
        weight is on the order of 200 grams (under 8oz).
        
        I did hear that one member of our World Champ team entered a locak
        HLS contest with one of his larger rocket gliders (without rocket
        of course), and was doing rather poorly on his own. He got someone
        with a strong throwing arm to do the launching for him (is this
        legal?) and ended up winning the contest!
        
        In the Free Flight HLG events, it really has turned into more of
        an athletic event than one of modelling skill. Is HLS that way as
        well?
        
        The first reference I recall to a HLS was the Zephyr, published in
        the May, 1981 Model Avaition. It was available as full size plan
        #332, for a mere $2.00 back then (current price may have
        increased). Span was 1.3 meters, which seemed big to me for hand
        launching, but well under the 1.5 meters that now seems accepted.

Wow, this is really weird. I thought I was the one who called Bob "Mr. Kaplow".
And the entire reason was I couldn't remember his first name and just calling
him "Kaplow" seemed kind of disrespectful, especially since I was thanking
him for entering the airfoil data. So, thanks Bob!

On to hand launch gliders (the RC type). Being a lazy sort, I took the advice
of a few notes back, looked at several of the kits, and finally ordered a 
Flinger from Sheldons. I really wanted the Gnome, but every time I called Hobby
Shack they claimed the kit would come "in two weeks".

Dave

As part of buying a couple of Amigo II R/C gliders I got plans to their Jolly 
which is a small free-flight glider. It's about the same size as the glider 
that Kay had at the last DECRCM meeting and I'd be willing to loan out the 
plans to anyone who'd like to copy and build one. I don't have the facilities 
to copy them (seems to be about 15x36" sheet)

Jim

I thought I had seen someone ask about the Jolly but I could only find a 
reference to Larry Jolly in 124.2

    I just acquired a hand launched glider. What kind of radio rec. is
    used? There's not much room so my standard receiver won't fit. Also
    what is good source for mini. receivers?
    
    Ron
    

Re: -.2

I'm the one who asked for suggestions on HLGs. The Larry Jolly Flinger came
up, and that's the plane I ended up getting. I'm about 60% through building
it. It's pretty simple. I made one modification to the kit: the wing is 
supposed to be built in one piece, but I made it a 2 piece wing so it'll be
easily transported. I only hope that the plywood wing rod will have the needed
strength. I've already folded the wings of a 2 meter plane just by hand 
launching!

Re: -.1 Ron Watts

I plan to transplant the radio from my Metrick 2 M to the Flinger. It's a 
Futaba mini system. 2 S33 microservos, a 4 channel receiver (R4H?), and a 
250mA battery. I still had to widen the fuse a bit so I can get a decent 
throw on the servo arms. The S33's have a pretty small swing angle, so you need
to make up for it with arm length.

    I'm not sure what a plywood rod is, but the Flinger wing is pretty
    tough, and a two piece version should work okay. Mine is still in
    perfect condition after 5+ years. The fuselage is another story.
    
    The weak points are the rear, wing bolt retainer. I finally went
    to a steel captured nut, and beefed up the surrounding structure
    with ply. Also the vert. fin will snap easily. I used a 1/8 x 3/16
    spruce fin l.e. running full depth to the bottom of the fuse.
    Carbon fiber doublers could be used also.
    
    Terry
    

>>  I'm not sure what a plywood rod is, but the Flinger wing is pretty
>>  tough, and a two piece version should work okay. Mine is still in
  
The wingrod is what holds the wings together while flying. A "box" is formed by
the top and bottom spars and the front and rear braces, so I cut a piece of
plywood (with a dihedral angle) to fit in the box. I'm worried that during
a strong hand launch, the stress on the wings will snap the rod.    

>>    The weak points are the rear, wing bolt retainer. I finally went
>>    to a steel captured nut, and beefed up the surrounding structure
>>    with ply.

Sounds like a good idea. The fuse is already together, but I can still add
some ply around the bolt area.

    re .23
    Okay, I get the picture of the wing joining method.
    Assuming the plywood V joiner is at least 3/16" thick, I wouldn't
    worry too much about it snapping in the vertical axis, but if it
    is plugging into the stock root spar structure, there may be a concern
    with sufficient strength in the fore/aft axis. There's a lot of
    inertial loading in the fore/aft direction at both launch and (hard)
    landing, and the outbd. ends of the ply joiner could introduce a
    stress riser point that the original engineering didn't allow for.
     
    Terry
    

Had a ball flying the Cuperosa at lunch today.

Longest flight was 41 seconds from hand launch - tho I did 
a few up-start launches to trip it.  Took out 3 pieces of lead
in the nose and it still raises its nose too fast after a 45 degree dive.

Fun Stuff.

Bye          --+--
Kay R. Fisher  |
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>a few up-start launches to trip it.  Took out 3 pieces of lead
                            ^^^^ make that trim
>in the nose and it still raises its nose too fast after a 45 degree dive.

As it turned out I wasn't changing the trim as I removed each piece of lead
and since I launched right into a dive test I didn't notice it needed down
trim.  But I re-trimmed at lunch today and still am flying without the lead.

I removed (ripped up) the top Monokote hinge seal and now have almost
no aileron differential (because now the aileron hinges from both top
and bottom - strange but true).

It turns really neat now with almost no loss of altitude or speed.  I can
do figure eights at eyeball height in the soccer field.  The only thing strange
is the way it goes up on tow.  If I let it get ahead of me a bit and need
some hard left correction it tends to kinda resist for a second then makes a
violent left roll and eventually follows thru with a turn.  Bear in mind that
the reason I was crooked on tow in the first place is because the wind changed
to the side and it tended to kinda weather vane into the new wind direction.

Here is a thought.  Since I'm not in the cockpit and don't have a little 
piece of string taped to the front canopy - how can I tell if I have too
much aileron differential or too little?  Just to make things more complex
how can I tell if I have too much aileron/rudder coupling?  That's a tough
question since I have both.

Love that Chuperosa.

Bye          --+--
Kay R. Fisher  |
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    Re. .26
    
    Kay,
    
    do I remember correctly that you only have one servo for rudder and
    ailerons? Do you think it's possible to fly the plane on ailerons only?
    This is important if you want to find out the correct degree of
    differentiation.
    
    As far as I understand it: Differentiation is needed to make the ship
    roll around the fuse axis (not a line in either wing panel). Since an
    aileron deflected downward gains more lift than an aileron deflected
    upward loses (with the same deflection angle), you try to reduce the
    downward throw and increase the upward. I understand this is the main
    reason. Balanced drag of the two wing panels and reducing the risk of
    tip stall are additional reasons. So... if you want to find the correct
    differentiation for your ship, fly it on ailerons only and adjust it to
    rolling around the fuse axis.
    
    Coupling of rudder and aileron is more difficult, and I'm afraid that
    you would not find one correct setting even if you could watch a woolen
    thread on the cabin. As I remember from learnig to fly a full scale
    glider, there are situations (stable circling in a thermal for example)
    where the rudder goes a bit into the circling direction, but aileron
    already goes a bit out. Sure, coupling of both helps to make the ship
    responsive as long as you are not used to work on both sticks without
    too much thinking. But I think (experts, correct me when I'm wrong)
    that you need independent control of rudder and ailerons when you want
    to achieve maximum performance from a given plane.
    
    Regards,
               Hartmut
                                    

>    tip stall are additional reasons. So... if you want to find the correct
>    differentiation for your ship, fly it on ailerons only and adjust it to
>    rolling around the fuse axis.

Actually Hartmut - I am unwilling to experimentally try anything that I
am not positive will be an improvement.  What I was looking (hoping) for
was a definitive way of testing to know if the differential and 
aileron/rudder coupling is correct.  For instance the method of a high
speed pull up while flying directly into the wind to determine if
the rudder is trimmed correctly.  The bottom line is since I removed
90 percent of my aileron differential this Chuperosa flys so good
I don't want to change anything unless there is some observation that
I can make to convince me that improvement is possible.  Also since
all my differential and coupling is done mechanically (even tho I'm
flying of a Vision I only have two micro servos on board) it is not
easy to try another setup.

Speaking of the Chuperosa I had it in the Acton soccer field again today
at lunch time and the longest flight was 1'32" off a hand launch.
I almost caught a bubble but didn't fly good enough.  Ironically
after another 10 or 15 minutes I got lazy and took two flights up
off a high start and both were shorter flights than my best hand launch.

Just waiting for the day that I can thermal out from hand launch on
flat land.

Bye          --+--
Kay R. Fisher  |
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Watch the grass swirl and turn upwind in your search pattern. So says the Old 
Buzzard.

I really enjoyed the soaring book and I'm looking at an RC HLG as a winter 
project next year (since it involves buying a properly downsized radio)

1m32s is amazing! Keep up the practice Kay and keep us informed.

	I completed the Flinger RC hand launch this weekend. Its maiden 
	flying session was Saturday, and it was very short. After a couple
	easy hand tosses it was clear that it flew fine and needed no trim
	changes, so then I gave it A GOOD TOSS. Snap went the wing. The 
	plywood rod that I used to join the wing halves was just too weak.

	[A little background here: The kit is designed for a one piece wing,
	but I decided to build it in two pieces to be easier to transport.
	I cut a piece of ply, with included dihedral angle, to slip into the 
	"box" formed by the upper and lower spars and the front and back 
	braces.]

	Luckily, there was no damage from the landing, so all I need to do
	is figure out how to make a stronger joiner rod. My first cut at this
	is to glue back together the original ply piece, then reinforce it
	with carbon fiber. It's also been suggested to me that I make it out
	of aluminum. Any other ideas are welcome.

	The rest of the plane came out nicely for the most part. Total weight,
	with radio, is 13.3 oz. I can't comment much on its flying performance,
	it was only in the air for a total of about 15 seconds. Once I get it
	back into flying condition, I plan to have a toss-off with Kay and
	his Chuperosa!

	Dave

    Dave,
    Just as a suggestion...
    
    They make some carbon fiber sheet stock. .007 thick and app 3" wide.
    I think Bob voilet sell it. Laminate a couple of layers of this
    between 1/16" sections of plywood. Then cut the center brace from
    this. Matter of fact, I think Bob sells something like this. You
    want the carbon fiber on edge from top to bottom.
    
    Tom

    The carbon fiber should do the job, especially if you make  two
    joiners, full depth of the spar box, and on both front and rear.
    This will require cutting slots in the root ribs so that the joiners
    can slide in next to the spar. The Orbiter uses two 1/32" ply joiners
    without carbon fiber, and no one has reported any trouble.
    
    Terry
    

	It looks like I may have finally licked the wing joiner problem on
	the Flinger. After having again broken the carbon fiber reinforced
	plywood joiner, I bit the bullet and installed brass tubing and steel
	wing rod. It cost me an extra ounce, bringing the total weight to
	14.3 oz. 

	I got in a couple dozen hand-launched flights Saturday before a failure
	of the rudder control horn grounded me. Actually, I was flying it all
	day with only half an elevator: the dowel which connects the two halves
	of the split elevator had broken, leaving me with control of only one
	elevator. The net effect was just a loss of sensitivity.

	The plane flies like...well, like a glider. A small one. It really
	does turn on a dime, but you definitely have to keep the speed up.
	My best launches got around 40 feet or so of altitude, and unless there
	was a thermal nearby, it came back down in a hurry. With 15 second
	flights, you get a lot of landing practice. Twice I caught some good
	air for flights around the 1 minute range, but after about 45 minutes
	of tossing it my arm started to feel like spagetti. I have new respect
	for Helmut Lelke, a guy who seems to get more height handlaunching his
	two meter than I do with the Flinger. And I've seen him do it for hours
	at a time. 

	I intend to cut a finger hole in the bottom of the fuse next because
	grasping it by the sides, even with sandpaper for better grip, just
	isn't good enough. 

An HLG!

Al Ryder called on friday and we got off onto HLG topics and then Saturday I 
had to go out to Active Electronics to pick up some stuff and I stopped by CMRCM
on my way home. Who was there but Dave Walter with his Flinger. He gave a demo 
and let me have a couple flights and I was sold. I haven't gotten one of my 
gliders flyable since I got back into it and I was "hooked again". My wife 
witnessed it and thought it might be nice for popping down to the neighborhood 
school yard after supper (since I'm 45 minutes away from my two "power" flying 
fields)

Al Ryder gave me some pointers to places that have some in stock and I'm not 
sure it will wait until the  "winter project" I had planned it for ;^)

I stopped at Tom's last night and bought a Gnome from The Midway Model Company.

60" polyhedral wing
"small cord optimized" Eppler 205 section (their wording/spelling, not mine)
375 sq in area
12-15 oz final weight
4.6-5.8 oz per sq ft wing loading

Only HLG in the store and I had decided to get one, so home it came.

I went through it last night and was pleased to find that EVERYTHING was precut 
(except the wing sheeting) and rubber banded together. The ribs were perfect 
with exact shape/size spar notches and clear, straight grain. The plans have the 
rib patterns on them and they were rolled, not folded.

I pick up the pair of 133 servos 8/2 and I hope to have the plane done to the 
point where I need them by then. If it survives, I'll bring it to the next 
DECRCM meeting.

    I'm just finishing the complete system repair/overhaul of Terry
    Sweeney's old Gnome, and I like what I've been working with.  Enough so
    that I wouldn't hesitate to buy one new, although I haven't yet seen
    one fly.  I'll ask Terry to enter a review here.

    There are some problem areas.  The top of the fuse at the wing leading
    edge is a weak spot; this one had been broken there more than once, the
    nose having broken downward.  Put carbon inside the fuse along the top
    of the sides or consider a redesign of the wing-holding mechanism.

    Put a Robart's pin hinge at the bottom of the rudder.  The rudder is
    cantilevered from the top-to-mid hinge down to where the horn attaches
    at the extreme bottom of the rudder. That causes the built-up rudder to
    flex, the hinge to yield, and the control to be sloppy.  

    The rudder can deflect into the elevator; think about changing that.

    Terry says the delicate, built-up wing is really super strong!  

        I have been flying the Gnome for several years now and have learned
    a lot about its virtues and drawbacks. The wing looks a bit fragile but
    looks can deceive. I would describe them as bulletproof. If I were to
    build another pair I would pay particilar attention to the transition
    from balsa to covering. In fact I would probably sand a slight droop
    transition area mid bay near the high point to prevent a step from
    happening. In conjunction I would attempt to get as much spanwise
    tension and as little chordwise tension to assist in accurately
    portraying the E205. The other thing that needs changing is the wing
    attatch. They are so strong that they can break the fuse several
    different ways. I can't even begin to count the number of times that
    area has failed. (two fuselages) The best attach I have seen is on a
    Chuperosa. It uses a single 8-32 nylon bolt at the high point to snug
    the wings on to the fuse rails which are covered with rubber. The
    rubber keeps things aligned well and the bolt breaks at just about the
    optimum force to protect both wings and fuselage. In addition a
    sideways impact pivots the wings preventing additional damage. I
    would strongly recomend some changes to the Gnome to avoid the weak
    fuse syndrone.
          If a new wing attach method were employed then a little beef
    immediately in front of and behind the wing would make the Gnome a
    durable flier. It would be a good idea to leave some room at the CG
    for ballast. A friend of mine regularly uses up to 8 ounces with good
    results in his 4 year old Gnome.
          Flight character is very manageable. It does suffer a bit from
    the curse of polyhedral. Rapid turn reversals are accompanied by a
    distinct tendency to balloon. This is caused by pitch up produced
    by the forward poking wing tip. I think the Gnome could benefit from
    a slight reduction in polyhedral in both inner and outer bays. The
    other quality it has is short coupling in pitch. This means you can
    get into and out of trouble extra quickly. It also translates into
    nimble handeling when banked. It is pretty good at catching those
    small thermals 10 to 20 feet above the ground.
       
    
    
    
    

         I meant to comment on the Flinger while I was on the tube but got
    carried away. A few notes back there was mention of joining the wings
    with a CF gusset. A friend of mine did just this about two years ago
    and in spite of some heavy duty ground contact has never had a problem
    with that joint. I believe he used a 1/32 ply core sandwiched by a 
    couple of 015-020 of CF. It is press fit and never seems to loosen.
         He has the stab removable and made a nifty carrying case of foam
    rubber,blue foam, and plywood that also holds the transmitter that is
    robust enough to survive the most punishing flight of all. (The
    friendly skies) 
         When he first built it he had a lot of trouble slowing it down to
    effective thermaling speeds because of an annoying tip stall. He and I
    reasoned that it was probably connected with the low reynold's number
    created by the 4.? tip chord. We conducted some one sided experiments
    with trip strips untill we got a good snappy stall towards the side
    without the trip. We then duplicated the trip on the other side and
    pretty much cured the problem. It now can slow down to the point where
    the glide degrades without dropping a tip.
         Applying what the Princeton tests indicate a suitable trip would
    be 1/16 wide * .007 at the tip enlarging to about 3/32 * .010 for the
    main span.
         Although there is something different in the way they fly there 
    was no substantial difference in penetration or sink rate in a one
    hour thermal ridge flight of the Chuperosa and Flinger. I wish we had
    taken pictures. At one point the pair were soaring nicely about 75 ft
    out and up inverted! In the background was a conventional hang glider
    and one of those high aspect ratio parachutes all sharing the same
    lift. We each flew two 270MA batteries  untill empty and went home all
    smiles.
                                       Terry Sweeney
     

I'm planning to build a pair of gnomes in parallel. The stock kit and then 
another with some mods. I did get some carbon fiber and I was planning to run 
some down all four corners of the fuselage as well as laminated into the tail 
and the typical wing strip. I'm going to make several tails until I get one I 
like. I like response in the rudder and was thinking of increasing it a little 
to avoid deflection into the elevator. I've made patterns of all the ribs and 
fuselage pieces so I'll keep rebuilding it until I'm satisfied. I taught myself
how to fly 15+years ago on a Graupner Amigo II glider and I';ve always enjoyed 
"silent flight" I just hate the hassles of driving to a power field or unwinding 
a high start to "relax". I've got two school athletic fields within 1/2 mile of 
my house and I'll be able to pop down after dinner and "toss a few". I like the 
idea that I can hook up to a highstart or slope with it also.

Tommorrow night will be the building frenzy (my wife and daughters will be away
on a girl scout sleepout). The kitchen table is MINE! (and then I don't have to 
clean a spot in my shop first ;^)

Thanks for the suggestions. More as they're built and flown.

	Re: .38 (Sweeney)

	OK, I give up. What's a "trip"?

	I'm flying a Flinger now, and just like you and your friend found,
	it doesn't want to fly at low speed, so it's tough to stay in those
	small tight thermals. I thought it was primarily due to the Eppler
	205 airfoil because it flies very much like my Metrick, which also
	has the 205. 

	I was considering building a second wing using a flat bottomed design
	(Clark Y?) to see if it improved the low speed handling. But if this
	"trip" thing does the trick, it might save me a lot of time.

	Dave

    
        A trip strip is also Known as a turbulator. It is some kind of 
    of a distirbance placed on or near the wing to promote a transition
    to turbulent flow. For instance the dimples on a golf ball are trips
    that allow a much smaller wake than would be generated by a smooth
    ball. I have heard that a very long time ago some observant person
    noticed that scuffed and dirty balls went much farther. In the case
    of a wing there is a region past the high point towards the rear where
    a cylindrical rotating "bubble" forms. This bubble can be quite large
    on model size wings flying slowly.(low reynolds numbers) By promoting
    a transition to turbulent flow the size of this bubble can be made a 
    lot smaller thus reducing drag and also delaying the angle at which
    stall occurs. In addition the stall becomes a little more predictable.
         In the case of the flinger the tapered tip panels are pushing
    the lower limit in possible sizes at least for an Eppler 205. The close
    proximity of the tip flow coupled with the small chord produce a fairly
    sharp stall starting at either tip and propagating inboard. In simple
    terms its hard to fly slowly especialy while banking. To help this
    situation a strip of thick tape is applied at 40% of the chord. By
    thick I mean thick for tape.(.007->.012) The trip strip is best made
    approximately .17% wing chord thick and at a proportion of 1/8 in wide
    for an 8" chord. As I mentioned in the earlier note you can apply it
    one side at a time to get a relative idea of its merit.
    
                                            Have fun
                                                Terry Sweeney
    
    

It might be reasonable then to use trim tape in 1/16th and 3/32nd" widths on the
monocoat as a quick and easy test?? I was surprised when you said to put it onto
the spars (and then quoted 40%) since I had always heard of it used closer to 
the leading edge. 

Sounds like something else to play with once I'm trimmed and flying

    Turbulators work best at the leading edge.

    As stated, they break up the laminar flow and provide instead a
    turbulent Boundary Layer flow over the wing.  This results in a
    reduction in the size of what's usually refered to as a Separation
    Bubble, an area of stagnant flow located over the low pressure area on
    the top of the airfoil.  Separation Bubbles induce drag, and also
    severly impact an airfoils ability to generate lift.

    The leading edge placment allows the boundary layer turbulent flow to
    become well established as early as possible over the chord of the wing.
    The idea is that the turbulent flow exists only in a VERY small region
    directly over the surface of the wing.  Laminar flow occurs in a layer
    above the turbulent layer.

    A piece of kite string, or a small diameter piece of piano wire, located
    just above the center of the leading edge is what I've seen and read as
    being the optimal location.  A few times, I've seen installations that
    have 2 ro 3 turbulators, separated by 1/8 to 1/4 inch, one right behind
    the other.

    The idea is to "rough up" the wing surface enough to induce the
    turbulent flow across the entire wing surface, without introducing a lot
    of additional drag.  A 12 Mil piece of tape may not have a sufficient
    enough profile to do the job.

I got the entire fuselage done and I got the wing completed except for the 
webbing and the top cap strips. I build the stab but not the vertical fin (I'm 
going to build a fin leading edge form since I'll be building a few) I ran out 
of CYA and had to take a break to work on the deck I'm building. I pick up the 
servos on thursday night and hope to get back to it at that point. I used Dave 
Brown's carbon fiber and that was an interesting experience. I'm going to try 
a pod and boom version once I see how my balance comes out.

Re: .43

Terry Sweeney contacted me off-line (last week) and stated that his 40% back 
placement was from the Princeton windtunnel testing. Hopefully he will fill in 
the details when he can.

    This note is a follow-up on my experiences with Terry Sweeney's old
    Gnome involving the use of small Nylon wing bolts.

    A 4-40 Nylon screw is more than sufficient as a wing bolt for the
    Gnome.  The original wing bolt, according to the plans, was a 10-32 
    Nylon screw inserted from above into threads in a plywood block below
    the trailing edge and above the finger hole.  The front of the wing has
    a forward-projecting dowel that passes through a bulkhead and the rear
    of the hatch.  The Nylon screw is subjected to shear during my typical
    landings and to tension during most of my flight  The 4-40 replacement
    survived all but one of my four to six fuselage-damaging crashes; it
    even survived a collision with a sapling that cut one wing right off. 
    I conclude that 4-40 is still too strong; a 2-56 will be tried next.

        To convert the assembly from 10-32 to 4-40 I did the following. 
        A #121 Fourmost Products Bulkhead fitting is a Nylon 8-32 screw
        with a 3/32 hole down the center.  I cut off the end without
        threads and screwed it into the plywood block from below and zapped
        it in place as a bushing.  (It is a loose fit in the 10-32 hole.) 
        I then cut off the excess and drilled it out with a 1/8th drill to
        clear the 4-40. The 4-40 socket-head Nylon screw is inserted from
        the finger hole up through the block, through a new hole in the
        rebuilt wing, and into a nut above the wing.  The next version
        will have the nut flush with the wing surface.

    The next time the fuselage breaks I'll cut off that leading edge
    bulkhead and install another small Nylon bolt up front.

I've got the Gnome built and I'm currently covering it (just the wing left) and 
then I have to balance it and install the radio. I'm waiting until thursday when 
I get my 250mA battery pack.

I used a pair of 4-40 bolts at the trailing edge. I can always leave one off and 
still have a bolt hole to use when I can't get the broken part out at the field.

I enjoyed building the kit and it came out reasonably well. I hated doing the 
cap strips and webbing but it is a necessary evil. I used a LOT of carbon fiber
and find that the fibers are a b*tch to deal with. The good news is that the 
tail is light and strong and I doubt if I'll fold the wing even if I use a brick 
for ballast.

Small changes I've made:

I used .020 music wire for the pushrods instead of the cables. The music wire is 
plenty stiff enough and the slop is minimized with the use of the tubes. I'll 
also move the connections out on the horns to minimize the effects of any slop.

Carbon fiber on both sides of the stab, rudder, and fin (along all edges). This 
looks a little tacky under the transparent yellow monocoat but I feel better
with it there. I also did both sides of all dihedral joints (top and bottom) as
well as a long continuous (I've been told unnecessary) strip the entire length 
of the lower wing spar.

>    <<< Note 124.46 by NOEDGE::REITH "Jim Reith DTN 291-0072 - PDM1-1/J9" >>>
>                              -< Gnome progress >-
...
>with it there. I also did both sides of all dihedral joints (top and bottom) as
>well as a long continuous (I've been told unnecessary) strip the entire length 
>of the lower wing spar.

Jim - they have published several test results in the last couple of years
of wing failures and it is almost never the bottom spar that fails.  It is
the compression of the top spar - so if your going to put carbon fiber on only
one spar - the current thinking would be that it is more valuable on
the top of the top spar.  But it sure seems natural to think that the
bottom would fail from tension.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

    Kay,
    	What (if any) results are had by putting the carbon fiber along
    the side of the spar?
    				-------
    				|    ||
    				|    ||
                       Spar --->|    ||<--Carbon fiber
    				|    ||
                                |____||
                       
    
    
    Tom

>    Kay,
>    	What (if any) results are had by putting the carbon fiber along
>    the side of the spar?
>                                    -------
>                                    |    ||
>                                    |    ||
>                           Spar --->|    ||<--Carbon fiber
>                                    |    ||
>                                    |____||
>                       
>    
>    
>    Tom

None - that is I have seen no tests in this configuration.  I can speculate
however.  Since the failure mode of spars is compression of the upper
section - that is where you want to increase the strength.  Carbon
fiber is excellent in compression (with good adhesion!).  Therefor
you get a big win for every piece of carbon fiber along the top edge
and less and less win as it works its way to the bottom.  Now of course
if you pull a lot of outside loops you want the strength at the top and bottom.
But most glider wings are trying to not fold on winch or pulling out of
high speed dives.  So I would guess there would be no particular advantage
to the side system.  But I can think to two advantages of complete carbon
fiber spars.

1.  You the the strength built in - no need to start adding stuff for strength.
2.  It could be perfectly straight and a consistent weight from sample to 
	sample.  Ever go shopping for GOOD spars when scratch building!

For what it's worth - I've always wondered about a thin strip of aluminum
on the top of the spar?  I don't know what would be a good adhesive to
use between balsa or spruce and aluminum however?

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

... are you saying that carbon fiber would be beneficial bonded (well) to the 
top on the top wing spar (thus withstanding/compensating for the compression of 
the top wing spar)??

Speak now as I haven't covered the wing YET but I will one of these next couple 
of nights.

Cranking up to fly this weekend

Jim

P.S. Dave Walter: How about a status report of your winch flights with the 
		Flinger this past weekend.

	Matter of fact, I DID enter the Flinger in 2 meter class at the
	contest this weekend. I think I ended up near the bottom of that 
	class. The problem is that the Flinger is very light, and it was
	quite windy Sunday. I simply couldn't make any headway into the
	wind to get to the lift, so my flights were in the 1.5 minute
	range. But I got good landing points due to all the launch-land
	practice.

	I was a bit nervous the first time I put it on the winch. Already
	one plane had folded it's wings on launch, and the wind was shifting
	around so it wasn't always from the best direction. With a sturdy
	plane you can just power through a cross wind launch, but the Flinger
	is so damned light I wasn't sure what would happen. The first 2 
	launches were exciting: the moment the plane was out of my hand it
	veered towards the pits and it took significant rudder to get it
	to straighten out. Thereafter, with a light touch on the winch switch
	it went up straight. On the third launch, I gave it a healthy toss
	to start out and it went up without any problem. I normally have no
	problem with winch launches, but this was a real handful. Certainly
	no zoom at the end, either.

	Regarding the carbon fiber discussion: If the Gnome is anything like
	the Flinger, no fiber is needed in the wing. At least on the Flinger,
	the wing is probably the most rugged part (it has a D-tube structure).
	The tail section is by far the weakest link, and I've already cracked
	the fin off once. If I was going to spend any time with carbon fiber
	(*gack*) I'd put it in the tail.

	Dave

>... are you saying that carbon fiber would be beneficial bonded (well) to the 
>top on the top wing spar (thus withstanding/compensating for the compression of 
>the top wing spar)??

Yes - but this should be done before the spar is in place so as to compensate for the
thickness of the carbon.  If you just bond after the existing design is together
then you will have a lump and distort your airfoil.

As for top - if you have the time and have the fiber (with the Dave Brown tow you end
up with enough to play with for several airplanes) then do both top and bottom since
it as almost weightless in these small quantities.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

I had looked through all the notes with search for carbon fiber when I started 
and there didn't seem to be a consensus as to where to put it. Like Dave's 
Flinger, the Gnome is a D tube construction so I'm sure the wing will outlast 
most everything else. I'm building several fuselages with slightly different 
sizes/shapes. I'll be able to fly this for a while.

Jim (the carbon_fiber keyword fairy)

Putting it on both sides of all the tail feathers REALLY stiffened them (now if 
I could just get it off my fingertips ;^)

    The "Current News" column in the Sep'90 RC Report, has the results of
    some experimentation that was done with spruce, balsa, and carbon fiber
    in a variety of spar configurations.  On non-acrobatic designs they 
    advocate 75% of the carbon fiber be laminated to the top of the spar to
    resist compression forces.  None of the spar caps in the wing sections 
    built this way ever failed in tension before the shear web failed and
    allowed the cap to buckle.
    
    The strongest spar they acheived, was a solid balsa web, capped top and
    bottom with carbon fiber.  It was over three times as strong as spruce
    spars with a balsa web of the same weight.  A horizontal grain spruce 
    spar, half the thickness of the balsa one, weighed the same, and was 
    nearly as strong when capped with some carbon fiber, so a little carbon 
    fiber apparently goes a long way.

    On a comment by Terry Sweeney a couple of weeks ago when he was still
    searching for suitable trip material,

>>  a suitable trip would be 1/16 wide * .007 

    It happens that the carbon laminate I'm using to repair the Gnome is
    0.007 in thickness.  I doubt if Terry had put a micrometer on it; I
    just did.  (Ironically, I got the laminate from Terry.)

    This raises the possibility of adding "free" structural strength as a
    side effect, albeit only as strong as the shear strength of the
    covering to balsa adhesive unless the trip can be put under the
    covering --- such a trip would be  smoothed a bit by the film.

    I have not measured the total thickness of laminate plus glue.

I managed to dodge a few raindrops on saturday and get some trimming done in the 
morning and then about 3pm the rain cleared and I was off for the local little 
league field. I gave it a few "down the slope" trim flights and then reared back
and gave it a heAVE. It flew pretty good. I found that the wind was totally calm
and the air was pretty dead but there was a difference between the wet grass and 
the wet infield sand. I found "non-sink" over the infield dirt but not enough to 
gain any height, just stop sinking. Between Saturday afternoon/evening and sunday 
morning I broke it four times (minor, I'll explain soon) and ended up with about
three hours of flying. My arm is SORE.

The damage was limited to ripping out the wing bolt block (twice), breaking off 
the elevator horn and the rudder horn and breaking of the outside leg of a "Z" 
bend. I found that I needed to use 1/16" ply instead of the 1/32" I tried to get 
away with. I also soldered a small square of brass onto the end of the rod to act 
as a keeper. Al Ryder was right, a pair of 4-40 bolts is too much. The hold down
block gives out before the bolts (guess I didn't need to buy all those spares). 
I broke the horns by landing tail first in a panic pullout from a bad launch and 
the pushrods popped the horns but the carbon fiber reinforced tail didn't break!

I balanced without any need for weight (I installed the radio last and balanced 
it that way) but I did have to overlap my servos all the way forward under the 
wing. It's kind of hard to explain but the servos overlap at the end away from 
the wheel and sit diagonally across the fuselage with the output arm on the side 
away from the closer side. It works good and gives me plenty of clearance for 
the arm. My 10 lb max (never the same weight twice) scale seems to think it's
between 13.5 and 14 oz and it flys well enough that I'm not concerned. I hope to 
weigh it at tomorrow night's DECRCM meeting (BXB or the field??)

A question for the glider guiders that have read this far:

I told me where to locate the plywood reinforcement for the tow hook but didn't 
give and actual location for the hook. The block seems to be slightly in front 
of the CG. What is the general rule of thumb for the hook?? My arm really wants 
me to look into a small high-start in the future.

    Jim, 
    
    Here's  quick rule of thumb that will give you a workable tow hook
    location: At the c.g. point on the underside of the wing, swing
    an arc 30 degrees forward. Extend a perpendicular upward to the
    bottom of the fuselage. Place the hook there. This will probably
    be a conservative, but safe position. You can move the hook back
    slightly if launches aren't as steep as you like.
    
    Terry
    

Thanks for the quick response. I'm more concerned with stability than steepness.
I'll modify it tonight and give it a try soon.

Jim

	Here's a good way to handle the tow hook. Using the 30 degree method
	explained previously you will get a good beginning location, but for
	steep launches you will probably have to move it back. (My tow hook
	ends up almost directly under the CG). So make sure the block that it
	screws into extends back at least a little past the CG.

	Then drill holes back from the starting position spaced about 1/4"
	apart or so. That gives you several tow hook positions you can 
	experiment with. The Gnome is a light plane, so you can use a simple
	wood screw for a tow hook. You know those brass hooks that are curved
	like a question mark "?" with the threads at the bottom? I just 
	straighten them into an "L" shape and they work great for tow hooks.
	And since there are no machine screws to tighten, it's easy to move
	the hook from one position to another.

I was just sitting here complaining how my shoulder hurts thinking
it must be some flu but then I realized it was from HLGing at lunch
time.

I almost caught one but didn't do a good enough job of circling.
I gave up and used an Up-Start and on the second launch I finally
caught my first thermal with the Chuperosa.  Up 9.5 minutes
before I bailed out and didn't find another to stay up.

I was making modestly accurate measurements today and I usually get
30 second flights in dead air.  If I get even 2 seconds longer it is
either because I had a heck of a good launch (unlikely) or there was
some thermal activity and I should have been able to thermal out.
Anything less than 30 seconds means I launched into sink air or
had a bad launch (possibly).

Again - I should have been able to do much better but my thermal
circles are awful.  I really think the Chuperosa wants a polyhedrial
wing.  After I get into a turn I have to nutralize aileron and sometimes
even add opposite aileron and since I have mechanically coupled the
aileron to the rudder adding opposite aileron is not making circling
very efficient.  Also with the foam core wing it comes out heavier
than I would like.  Now that I have an accurate scale it weights
19.5 oz.  Originally it started off life at 17 but I've painted the
wing 3 times and had a few nose repairs and throwing finger hole
repairs.

On slopes this plane should be great - it cruises great and turns
on a dime with nice control - but it just doesn't have spiral stability
I would like for thermal circles.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

I sent Dave mail asking if he had gone out since I had a lunch commitment that 
prevented me. I thought it would be good since it seemed to just have the right 
mix of light breeze and warm sun. I hope the weather holds for tomorrow as we 
(Dave Walter and I) have made plans to exercise our arms at lunch.

I'm impressed!

I've only gotten a small (20-40 added feet) amount of lift a couple of times and 
that could have been either slope effect or whatever. I'll be out hunting 
thermals tomorrow!

I'll be building fuselage #2 for the Gnome with a tow hook and better nose 
support this weekend so I've got nothing to loose flying the dickens out of the 
current one.

Kay:

From the brief flights I had with your Chuperosa, I still think you should 
try adding some more throw to your ailerons. Heck, if it doesn't work out, put
it back where it was.

I too have problems circling tight with the Flinger. It really wants to drop
a wing and lose altitude. But if I keep the circles wide, I can't stay in those
little micro-thermals you find close to the ground. Soooooo....

I've decided to build another wing. The stock one uses an Eppler 205 airfoil, 
which covers a lot of distance well, but doesn't seem well suited to slow,
tight circles. And the small chord at the tip (5") evidently  makes for quick
and evil stalls. The wing I'm going to build will use the old Clark Y foil, and
I'm considering a constant chord at 6". This time I will put 1/4" or so washout
in the tips, and possibly use tip-flairs like on the Chuperosa. It's
also going to be a single piece wing with span-wise sheeting on the top leading
edge only. I figure that'll reduce the weight 1.5 ounces compared to the 
original wing (which is a two piece affair with a steel rod). It will be inter-
esting to compare the performance of the two wings.

Dave

Interesting reply from Nov-1988.  I guess our moderator is moving
things.  Not a complaint - keep up the good work Mr. Moderator.

Yesterday - Monday 3-Sep-1990 (Labor Day) I finally thermaled out
from a hand launch.

After spending many days at various sites throwing my arm out
I finally did it.  I took it up and (it was very windy) out
as far as I dared and came back down and caught it after a 4 min
50 sec flight.  Was I happy.  Kevin Ladd and Charley Nelson were
busy talking Scale and I kept yelling - Hey!  -  LOOK where I am.

The amazing thing is it is the first day I can remember that my are
is not hurting after.  Probably because it was real chilly instead
of 80 degrees.

It was a lot of work though to try and make efficient turns with
the Chuperosa.  I would like to have one wing for sloping and
one for thermaling.  Also it would help if the thermal wing
was build up so that it could be lighter.

I'd like to say that I spotted the thermal and threw into it but
alas I was just chucking after every landing and managed to find one
building up over the runway.

Although I have a hard time making an efficient turn with the straight
wing - I must admit I have never had a plane that indicates thermals
with the wings as good as this one.  It really gives a pronounced
wiggle to the wings when it detects a bump.  

I wonder if I switch to a polyhedral wing - do you guys think I will 
loose any of that great thermal indicator capability?

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

Yesterday - Wednesday 5-Sep-1990 I spend a frustrating lunch hour
at Acton trying to hand launch into a thermal.  It was very
overcast (but cleared up nicely as I went back to work).

I never caught one but I had a couple of "ALL MOST"'s.

One time the breeze stopped and it started getting hot.  A lonely
hawk came over to torment me.  He started circling right over
my head about 100 to 150 feet up.  He was saying "Look Dummy!
It's right here - your standing in it!  I had time to try
three hand launches and couldn't catch it.  The hawk waited for
a minute then just went up out of site.  All the while staying
straight above me.  I was tempted to string out the UpStart but
figured it would take too long - besides I really wanted to
catch another one "the hard way".

Oh well - maybe tomorrow.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

A couple days ago I was over at the local lunch time glider flying field 
along with Jim Reith and Steve Smith. Conditions were perfect for thermaling
but none of us was riding anything up from a handtoss. Now who drives up but
Helmut Lelke himself, with that ugly blue 2-meter that most people would have
thrown out 2 years ago, but with which he consistently wins contests. He
throws it once to check the trims, throws it again and begins climbing like
he's in an elevator.

Jim looked over his shoulder at me with that "who the hell is THAT guy?" look
on face. It's really embarrassing flying with Helmut around. What's worse,
even when he TOLD me where the lift was, I couldn't ride it up like he could.

Dave

Yeah, it was fun. The part that really twisted the knife was when, after an 
upstart launch, I was thermaling up to meet him. I lost track of him and said, 
you must really be up there. His comment was that he was right up overhead but 
he had to go back to work so he was going back to his car. He HAD to come down!
He wandered over to his car and brought it in right at his feet. I picked up my 
jaw bone and went back myself. The gods are among us ;^)

    Having gotten my Orbiter flying closer to the way it should, last
    weekend, and now getting turned on to HLG again, I decided to haul
    the 6 year old FLinger out of the closet and see what it needed
    to restore it to flight status. For sure a new fuselage. Ok, for
    that I simply duplicate an Orbiter fuse. whiich is about 5 " longer
    but narrower and lighter and stronger. A slight mod will be necessary
    to allow the l.e. dowel mount of the Flinger wings (originals still
    in perfect shape) rather than the bolt on method of the Orbiter.
    
    The original Flinger stab and fin is useable but the Orbiters' is
    stronger so again I duplicate that (stab already done) except I
    reduce the stab span by ~ 1" (Flinger stab is 2" shorter than Orbiter).
    
    Tonight I stop by the hobby shop and pick up some 1\8"  lite ply
    and 3\32 balsa to build the quasi-Orbiter fuselage. Some adjustment
    will be necessary in the wing saddle area to allow for the 1+ "
    smaller chord of the Flinger wing, will probably shorten the fuse.
    a couple of inches.
    
    Then Kevlar pull-pull cord goes in for rudder control, eliminating
    more weight, and when all is finished in 1-2 weeks (dream on) I'll
    have a direct comparision between  an E-205, 380 sq. in, flying
    at 12-14 oz., and a S4061, 430 sq.in., flying at 17 oz.
    You are free to decide what this will prove.
    
    After that comes a duplicate Orbiter wing, built with polyhedral,
    no ailerons, and the S4061 airfoil at x1.5 thickness, courtesy
    of Glenns' program. What this beast will do is anyones guess, but
    it should look intimidating.
    
    Terry
    

As long as we're talking airfoil comparisons, I'm about one night's work away
from completing my second Flinger wing. The original is an E205 with tapered
tips. The new one is a Clark-Y with constant chord throughout the span, about
1/4" washout, and winglets on the tips. It should also be about an ounce lighter
because I'm building it in one piece.

I decided to build the new wing because the original, while a good penetrator,
is very difficult to circle tightly, so I can't stay in those small thermals
close to the ground. When it stalls, it drops altitude with a vengence. My hope
is that the new wing will fly slower, smaller circles. We shall see, we shall 
see.

Dave

In the Oct-1990 Model Builder magazine the Soaring column by Bill Forrey
has a picture and a brief description of Joe Wurts and his latest HLG.

It is his own design but uses a fiberglass fuselage from a Swift 400
by Flight Line Composites.  These are the people that make the Falcon 880.

I called them up for info on this fuselage and apparently so did a lot
of other people.  The fuselage cost $45 but they are going to kit Joes
design and I had them start a mailing list with my name on it.  So when
the kit is available I should hear about it and will pass it on.  I
don't know if you can save any weight with a small HLG fiberglass
fuselage but I want to tell you HLG fuselages really have to take a
beating.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

I assume that you saw in this latest issue that a 14 oz Chup (by the originator) 
took first!

Dave Walter and I went out in the windy drizzle yesterday and flew anyway ;^)
I was real DEAD air with extra weight from the water. I finished the day with a 
gust induced stall that bonked the plane in on it's nose and broke the wing 
bolts for the first time. I was very pleased that I broke the bolts without 
damaging anything else. I'm using a pair of 4-40 nylon bolts and it seemed 
just about right. I've flown with one bolt broken with success off the highstart 
but I like to try to have both bolts whole in case one bolt head snaps off. It
was real interesting flying with very gusty conditions and I did get a little 
daring and did my first loops and attempted to fly inverted but I didn't have 
enough down elevator throw to maintain level flight and I chickened out at about 
75 feet up. I guess I've been flying the Panic too much recently ;^) I tried
rudder rolls but didn't have enough speed and they didn't work out very well. I
figured that if there wasn't any lift, I might as well have some fun. 

This HLS has to be the best plane I've built so far. I've been able to go out 
and have fun at the drop of a hat and it's easy enough to get set up with the 
high start to get several flights in during lunch without the mess of the fuel 
goop to clean up afterwards.

I finally completed my latest handlaunch and gave it the maiden flight this 
weekend. This is the first plane I have designed on my own. It's very similar
to the Flinger: 59" polyhedral wing attached with dowel in front and bolt in
back, standard box fuse, and standard tail arrangement of rudder and elevator.
The wing airfoil is S3014. The flying weight came in at exactly 15 oz.

I wanted to improve the Flinger's wing loading and make the plane a little
less "darty". I increased wing area from 330 sq.in. to 400 sq.in. by adding one
inch to the wing cord. I also extended the nose to get the battery further 
ahead of the wing. It still required  1 oz. of lead to get the balance right,
but the overall wing loading dropped from 6.1 to 5.4 oz. per sq.ft.

I lengthened the wing-to-tail distance by about 1.5 inches to try to slow the 
response a bit. In sizing the tail surfaces, Helmut Lelke had suggested using
0.4 for the horizontal volume and 0.03 for the vertical volume. Using those
numbers, the fin comes out VERY big so I reduced it to 0.025.

Lastly, I paid a lot of attention to beefing up the finger hole below the
trailing edge of the wing, as that was the weak point of the Flinger fuse.

Flight review: So far, so good! My first flights were slope soaring at Bose.
This airfoil is very similar to the E205; it penetrates very nicely and 
retains speed. I flew it unbalasted in 10-15 mph wind and had no problem. It's
response is still nice and quick, great for the slope. Unfortunately, a hard
landing Sunday knocked the fin loose, so I'll have to beef up the attachment.

Flying in calmer conditions at an open field, I think it takes tighter, slower
turns than the Flinger did, so I'm hoping it will be easier to stalk low lying
thermals. But it still moves out and covers lots of distance when you want it
to. 

I'm happy with it! I think I'll save it for thermal hunting, and resurrect the
beat up Flinger for the more hazardous slope duty. 


Dave


PS: I have heard that Flinger kits are hard to get these days. I'd be willing 
to lend out my plans to anyone interested in building one. The instruction book
has a parts list so gathering materials would be pretty easy.

    I mmet Dave a Bose on saturday and I must admit, he's got a nice plane.
    He gave me some stick time on the slope and on the flat off an upstart
    in Southboro and the plane seems to have great characteristics. Holds
    it's speed well and has enough elevator to fly inverted. Should be out
    of sight when the serious lift shows up.
    
    Nice design!

    I started a Wristocrat HLG a couple years ago and quit after I screwed
    the wing construction up.  I am thinking about rebuilding this ship.
    What's the word on the Wristocrat?  I originally wanted it to fly
    light ridges.  My father had a Bridy Kastaway and another HLG he
    scratch built- they were a lot of fun?
    
    
                                                       Thanks,
    
                                                       Jim

    kit quality seems to be lacking and the stab pivot point is a major
    wear point. Use a scrap (remember size = weight) piece of hardwood as a
    bushing. I haven't flown/see one fly. Just two friends build it.

	The one Wristocrat I've flown was built a little heavy but flew pretty
	well. I think if you keep it light and strong it will fly very well.
	I know a guy in the CRRC club who owns one and loves it.

	Regarding my own HLG (recently named the Predator... it preys on 
	thermals!), I took it out at lunchtime today and proved that it thermals
	quite well indeed. I had two very satisfying climbouts from handlauch.
	It is easier to catch a thermal ride than with the Flinger because it
	circles slower and tighter without stalling and losing altitude. I 
	attribute this to lower wingloading rather than the airfoil change.

	Dave

	A humorous afternote: Upon finishing with the glider flying, I hopped 
	in my car, threw it in gear, and proceeded to drive right over the
	cut off tree stump I had parked right behind. Forgot it was there.
	When I slid off the back of it, it hung up on my chassis, my rear wheel
	floating in the air. The car looked like an overfed dachshund. $45 
	towing charge to get it picked up and moved 2 feet to the left.
	Gad, it's really embarrassing being me...

    
        DW1,
    
           Some advice, If you want to taxi over tree stumps, you
        should lengthen the undercarraige to get more ground clearance :)
    
                                                    DW2

    I am in the middle of building a Wristocrat at the moment. I am just
    getting to the end of the wing construction. I am building it with the
    flaps option, partly for the challenge of building it and partly
    because my previous two gliders have been rudder/elevator only and I
    was looking for something different.
    
    I was not very impressed with the kit quality - adequate, but nothing
    to write home about. Not very good diecutting, things like that. 
    
    I would be interested to compare notes on the finished models.

I got in my first thermal soaring with my HLG Wristocrat yesterday. It was 
great! I must admit I cheated on the launch though. Take a Vortac bomb hook
and servo-tape it to the top of the wing. Install the release mechanism under
a Sig Kadet Senior. Attach HLG, fly to desired altitude and release. Start
hunting for thermals.

They were booming at the PPRC field here in Colorado Springs yesterday. I had
let my buddy Steve have the sticks and he caught the first one. He flew for
10 minutes or so and then I took it for another 10 before the thermal moved 
too far off. We then took it up again and it seemed like the whole field
was one big thermal. Flew for about 20 - 30 minutes. I even had a hawk come by
and check out the interloper in his thermal. Finally had to come down cause my
neck hurt from looking straight up for so long and I wasn't sure how much
juice I still had in the 250mil flight pack.

I don't think I'll give up flying power, but soaring was a great way to end the
day.

Randy

    I just scanned back through this topic and boy, are there a lot of
    memories in here over the last couple of years.
    
    I was looking for something that stated the rules for HLGs. I know that
    it's defined as 1.5 meter but is there any maximum on the wing area?
    I'm about to start my model for Biddeford and I don't want to get there
    and find out I'm disqualified on some technicality.
    
    Tom Peghiny has 400 sq inches on his Kestral and it FLOATS so nice,,,

    No wing area limitation on HLG, or any other AMA glider class.
    

    We'll be waiting to hear how this secret weapon turns out.
    
    Low aspect ratio wings on small airplanes have a nasty tendency
    to be very draggy especially when turning.
    
    IMHO this is one big reason why the Chup turned out to be a better
    HLG than the Orbiter (435 sq. in.)
    
    Terry

    The Orbiter (with flaps) I saw at Bose was a nice performer on the
    slope. I won't be trying to throw a parachute but two wings will be
    built...

    Find a nit picker who tends to do his homework, give him a rule
    book, and be prepared to be bored stiff.  Preparation for last
    Saturday's contest caused me to study the Competition Regulations,
    and I have since gone through the issues of Model Aviation looking
    for any applicable changes.  However, I'm inexperienced, and my
    interpretations of the rules are not entirely trustworthy.


    Regarding the question about limitations on HLG wing area, the
    limitation is generous.  To quote the applicable C.R. sections,

       "3.3.  Sailplanes flown in AMA Soaring Competitions shall not
        exceed the FAI limitations for weight and total lifting surface
        area for model sailplanes.  Exception: The FAI nose radius
        restriction shall apply to one view only; however knife edge
        frontal area is prohibited.
          FAI Specifications:
          1.  Maximum Surface Area (ST) 150 dm2 (2325 sq.in.)
          2.  Maximum Flying Mass 5 kg. (11.023 lbs.)
          3.  Loading of the St. Between 12 and 75 g/dm2 
                      (between 3.95 and 24.57 oz/sq.ft.)
          4.  Minimum Radius of Fuselage Nose 7.5 mm (.295 in.)
              Exception ..... " [as above]


       "3.1   The following classes of sailplane shall be allowed for
        competition and the number of control functions (servos) are
        unlimited.
        3.1.1 CLASS A - Hand Launch Sailplanes.  Projected span limited 
        to 1 1/2 meters or less.  (Hand-launch only designates class and
        size.  Models may be hand-launched or launched by equipment
        provided by contest director (see rule 9.)
        3.1.2 CLASS B - Two Meter Sailplanes.  Projected span limited 
        to two meters but not less than 1 1/2 meters.
        3.1.3 CLASS C - Standard Class Sailplanes.  Projected span limited 
        to 100 inches but not less than two meters.
        3.1.4 CLASS D - Unlimited Class Sailplanes.  Projected span greater 
        than 100 inches."  [sic]

    There are other paragraphs that say you can enter smaller planes in a
    class for big planes.
    ---------------------------------------------------------------------

    Note that the rules do not prohibit a biplane or triplane; go for it,
    Jim Reith!  Applying the rules to an HLG, the total chord of all your
    wings cannot exceed one meter.  (Will we see Jim with a 4 wing plane?)

    Seriously, the wing loading limitation implies for an HLG an upper
    limit on area of about 700 sq.in.  Pay attention to all the rules if you
    are thinking of a total average chord much over 9 inches.  And as Terry
    says, the aerodynamics might get you anyway.  The designer of the
    Stylus (a low aspect ration HLG) admits to some flying penalties.
    
    Alton, wallowing in minutae

    No, I'm not designing a hand launch Panic 8^). I just meant that I'd be
    building a stock wing and a not so stock wing that I could swap
    between. Have I told you about my other new hobby? I took up the shot
    put 8^)

I've been looking around for a smaller than 270mah battery for my HLG stuff. 
Ace sells a 110 mah pack right off the shelf and I had Ray order one for me 
last night. It'll be under $20. I also noticed the place in the front of the 
MA issue that has 1/2AAA cell 50mah packs for $15. Now I know why I just got 
an ESV.

Well, this note's been dead for a while. I hope there are still a few folks
who do HLG out there.

I've been having a little trouble with the correct throwing motion. If I
try to throw it high it balloons and then stalls, but if I throw it 
straight out, I only get a launch height of about 20 feet. Is that
acceptable? I have the skeeter, and it came out to about 14oz. That
number may be +/- some due to the inaccuracies of my scale.

I've got the finger hole, and that works great, because I feel like I
can really crank it out there. Just like golf though, throwing hard
doesn't necessarily produce the highest launch, and I'm thinking that
I'm definitely lacking on technique.

Any tips?

Dave

    I'm sure Dave Walter will add his experience here, but the times I've
    flown Dave's Predator and thrown it for him, and watched him throw it,
    you have to throw it high. Maybe about a 50/60 degree angle. The trick
    is to punch down elevator at the top of the arc before it stalls and
    transition that momentum to forward flight.

    Well, I've never seen myself throw the Predator, but I feel like I'm
    throwing at the horizon, not up. I usually set the elevator trim so
    that it naturally wants to nose up gently. As a result, the path starts
    (mostly) parallel to the ground then arcs up smoothly. As Steve said,
    you feed in full down just before it runs out of airspeed. That takes
    some practice to get the timing. If you've ever watched an athlete
    throw a javelin, that's the closest motion I can think of to throwing a
    handlaunch glider. 
    
    Most Skeeters I've seen have come in at about 12 oz, but I think 14 oz
    should fly OK too. Maybe you could come down to the Acton field some 
    lunch time and join us. We go once a week or so. If you want to fly on
    the weekend, Callahan State Park in Framingham is your best chance to
    meet other glider pilots.
    
    Dave
    

>    Well, I've never seen myself throw the Predator, but I feel like I'm
>    throwing at the horizon, not up.

I'm sure that was most of my problem then. I think I was trying to
throw up much more than out.

>    If you've ever watched an athlete
>    throw a javelin, that's the closest motion I can think of to throwing a
>    handlaunch glider. 

Good, thats actually what I was trying to emulate. I found that if I
held the glider low and far behind me, and then did that running start,
I could really get it going.

>    Most Skeeters I've seen have come in at about 12 oz, but I think 14 oz
>    should fly OK too.

I really need to get an accurate scale so I can see how light or heavy
I ended up building the thing. Of course I've already dorked the thing
several times, so I guess I'll have to subtract for the extra CA. :) I'm
extremely pleased with its durability though. I even *landed* it upside
down once. The former that holds the front of the wing in was the only
thing that popped loose.

>    Maybe you could come down to the Acton field some 
>    lunch time and join us. We go once a week or so. 

That would be kind of haul from Nashua for lunch. Appreciate the offer
offer though. I guess I'll just have to keep flying with Jeff for
lunch... (One of these days I'm going to convince Jeff that gliders
are where its at!!)

>    If you want to fly on
>    the weekend, Callahan State Park in Framingham is your best chance to
>    meet other glider pilots.
    
Could you email me some directions? 

Dave