Conference vmszoo::rc

    Some hobby shops stock fiberglass arrow shafts to be used as pushrods.
    They are strong and straight and they are great for large planes.
    You might be able to use them instead of aluminum tubing.  They
    are in the ball park of 10MM, but I am not sure of their dimension.

    For an improved sellectoin of arrow shafts look under"archery"
    in the yellow pages.  Find a shop that makes arrows as apposed to
    one that only stocks completed dozens.  If an indoor archery
    lanes is listed they are a good bet.  If you have trouble locating
    a source for an arrow shaft let me know. Does anybody know the
    us equivelent to 10mm?  
    As for a ruff checking without an incedence meter;
    
    turn the plane upside down. Adjust the fuse of the plane so that
    a level put on the horizontal stab reads "0". Then place a level
    on the bottom of the wing. Now place a protractor so that the
    center of the protractor is on the trailing edge of the wing.
    Pivot the level on the trailing edge of the wing until you get a
    "0"reading. Looking thru the protractor view the bottom edge of
    the level. The reading you will get will be in degrees. This is
    your incedence reading. This will be a positive incedence reading.
    If to make this work you have to reverse the protractor and fulcrum
    of the level to the leading edge then the reading you will get will
    be negative incedence. This will only work on flat bottomed wings.
    
    						Tom

>    For an improved sellectoin of arrow shafts look under"archery"
>    in the yellow pages.  Find a shop that makes arrows as apposed to
>    one that only stocks completed dozens.  If an indoor archery
>    lanes is listed they are a good bet.  If you have trouble locating

I have fiberglass arrows - yeah I used to do that too.  They are too small.

>    a source for an arrow shaft let me know. Does anybody know the
>    us equivalent to 10mm?  

Slightly over 13/32"

>    As for a ruff checking without an incidence meter;
>    turn the plane upside down. Adjust the fuse of the plane so that
>    a level put on the horizontal stab reads "0". Then place a level
>    on the bottom of the wing. Now place a protractor so that the
>    center of the protractor is on the trailing edge of the wing.
>    Pivot the level on the trailing edge of the wing until you get a
>    "0"reading. Looking thru the protractor view the bottom edge of
>    the level. The reading you will get will be in degrees. This is
>    your incidence reading. This will be a positive incidence reading.
>    If to make this work you have to reverse the protractor and fulcrum
>    of the level to the leading edge then the reading you will get will
>    be negative incidence. This will only work on flat bottomed wings.
>    
>    						Tom

Are you saying that the main wing flat bottom should be parallel to the
horizontal stab or at some positive angle.  If positive then what angle?

              _!_      
Bye        ----O----   
Kay R. Fisher / \     

================================================================================

    Yes, flat bottom=parallel to horizontal.
    
    
    Some ships that create a lot of lift use a "0" or positive setting
    on the wing and a "0" or negative setting on the stab. The relationship
    of wing to stab shouldn't differ any more that +- 5 degrees max.
    
    IE, If the wing were set at +5 degrees then the stab should be set
    at "0" or some + degree setting. It's different on an RC plane as
    opposed to a full sized plane.
    
    I'm going back and reread your reply to see if I've missed something.
    
    
    						Tom

    
    
    If you get an arrow shaft they're going to ask you what size.
    
    Alum. arrows are measured in 64th of an inch. An arrow shaft that
    is a 2018 is actually a n arrow that measures;
    
    	20/64 in dia. and has a wall thickness of .018
    
    If you have a choise go with what they call an "X7" or a "XX75"
    (that pronounced "double X 75".
    
    The X7 is an extremely stiff shaft, the XX75 is less stiff.
    One other suggestion is to insert one arrow shaft into a second
    shaft. This may help it take punishment.
    
    
    One neat thing about a flat botttomed win g is that if one wants
    a slightly groovier ship at one has a flat bottomed wing all one
    need to do is shim the trailing edge of the wing and the flat bottomed
    airfoil will act somewhat like a semisemetrical airfoil.
    
    What was the CG like?
    
    						Tom

>    Alum. arrows are measured in 64th of an inch. An arrow shaft that
>    is a 2018 is actually a n arrow that measures;
>    
>    	20/64 in dia. and has a wall thickness of .018
>    

But I don't think they will have sizes up to 26xx will they - that would
be one fat arrow?

>    What was the CG like?
>    
>    						Tom

I was afraid you would ask.  I just threw it together and didn't check.
Since it called for a .10 to .15 and I put a OS 20 on the front I assumed
it would be nose heave and that would be good for me.  Before it goes up
again you can be sure I will have that right.  At the present time it
is not possible to measure after the fact since until I replace the main
shaft the engine is not connected to the rest of the plane.  But before
every body yells - I did ruff check and the CG was 1/3 back from the leading
edge of the center of the wing.  Course this wing is kind of delta shaped
so that was probably not enough - but with a good running 20 shouldn't
I have been able to climb?  The linkage to the elevator was also the pits.
Wire that flexed a lot.  Next time I'll have balsa wrapped to it to stiffen
it up.

              _!_      
Bye        ----O----   
Kay R. Fisher / \     

================================================================================

    There are a few things to be considered:
    
    1. A flat bottom wing is not flat on the top and the profile of
    the airfoil does make a difference on the amount of lift the wing
    provides. Therefore, the angle of incidence of the elevator/stabilizer
    is different from wing to wing.
    
    2. The distance between the elevator and the wing have a lot to
    do with it too. You can see the difference by observing the flying
    attitudes or caracteristics of, say, a patternship (fast but calm
    and precise in its ups and downs) and an aerobatics biplane (much
    bumpier and nervous).
    
    3. Of course, the balance is very important. Next time you don't
    check it, don't admit it. Nose heavy planes are harder to get off
    the ground. If they fly, they are relatively stable in their ups
    and downs. 
    
    4. One more thing is the weight of the plane in relation to the
    size of the wing and the power of the engine.
    
    I started with a Kadet Jr. (flat bottom wing) and later I helped
    a friend learn to fly with another Kadet (also flat). They are both
    very heavy planes for the size of wing and they don't like taking
    off until they are going at about six hundred klicks an hour. They
    need long runways, can't take any cross wind for takeoff, and seem
    not able to fly. When they reach critical speed, they jump off the
    ground nose up and make you look like a fool until you master their
    idiotic behavior.
    
    You have to analize your plane to see if anything is really wrong
    with it of whether that's just the way it is. I don't remember the
    size of your engine but a .40 size plane with a wingspan of 55 inches
    should weight about 3.5 to 4 pounds and still be able to take off
    without requiring the pilot to have a PhD. Of course I am talking
    about an average design, not about a CAP21.
    
    When you look at the other guys planes at the field you can analize
    and come to pretty solid conclusions. I am convinced that flat bottom
    wing do not make for good trainers. They don't even make for good
    flyers. Although a plane like the Goldberg EAGLE 63 is a good trainer,
    easy to learn with and forgiving, the Sig KADETS fly just as good
    as a bathtub with flatbottom wings. Summary: Planes apparently have
    the same caracteristics can be very diffferent.
    
    This is what I would do:
    
    1. Repair the plane adding to it as little weight as possible. A
    lot of epoxy, reinforcement, plywood don't help the weight scenario.
    
    2. Make sure the plane is ballanced, at least within reason. Tail-heavy
    is dangerous. Again, adding 26 ounces of lead to the nose doesn't
    do much for the weight/power.lift ratio.
    
    3. Eyeball the wing-stabilizer alignment. If it looks reasonable,
    it should be allright. The elevator throw should be at least 20
    times more efective than the incidence and should be enough to
    compensate for small errors. If it isn't for whatever reasons  
    (plane is half pound too heavy on the nose, stabilizer forms a 24
    degree angle with the wing, the connecting rod is too flexible and
    bends instead of moving the elevator, elevator hinges are stuck
    with too much Zap or epoxy,  etc), maybe you should burn the plane.
    
    4. Go to the field in a calm day, position the plane  at the very
    end of the runway and, if possible stand behind it to ensure it
    rolls in a straight line into the wind and give it gas.
    
    But then, again...
    
    Fern 

Kyosho Wingmaster progress report

I received the new Keel (Aluminum shaft) in the mail and put it back together.
Then I checked the CG.  I was nose heavy by about 1.5 inches.  In order
to pull it down I had to stick 18 ea 1/4 oz fishing sinkers in the Keel.
Still not enough so I taped a couple of steel shelf brackets to the horizontal
stab.

I increased the angle of attack just a washer or two more positive.

Saturday I'll try again.

              _!_      
Bye        ----O----   
Kay R. Fisher / \     

================================================================================

    
    Steel brackets on the horizontal stab???  Sounds scary to me!!!
    If you had trouble getting it up before (getting a little personal
    here) then I'd be worried that the extra weight is going to make
    it even worse.  Can you shift the receiver/servos/battery back
    to reduce the nose-heaviness?
    
    Bill

>    Steel brackets on the horizontal stab???  Sounds scary to me!!!
>    If you had trouble getting it up before (getting a little personal
>    here) then I'd be worried that the extra weight is going to make
>    it even worse.  

Doubt it.  It feels very light.

>    Can you shift the receiver/servos/battery back
>    to reduce the nose-heaviness?

No.  There is this receiver box suspended from the Keel and it's full.
This is an ultralight (no fuse).  What it really needs to avoid the
extra weights is the correct engine (OS10 FSR) and I refuse to buy a
special engine of a size that I never intend to use again.

Saturday will tell.

              _!_      
Bye        ----O----   
Kay R. Fisher / \     

================================================================================

< Note 246.11 by LEDS::LEWIS >
>    Steel brackets on the horizontal stab???  Sounds scary to me!!!
>    If you had trouble getting it up before (getting a little personal
>    here) then I'd be worried that the extra weight is going to make
>    it even worse.  Can you shift the receiver/servos/battery back
>    to reduce the nose-heaviness?
>    
>    Bill

Tried twice to go up Saturday.
The first hand launch was a bad throw (Kevin are you listening).
Sky King couldn't have recovered from it.

Bent some aluminum straight and tried again.
Next throw was better but still not straight.  Sky King might have
pulled this one out - I didn't.

Straightened some more aluminum and decided to do the plane a favor and
give up before we dorked it really bad.

Conclusion:
  The plane really requires a OS10 FSR or a 15.  Too much engine = too
  much weight.

  The plane is incredibly hard to hand launch because the only place
  you can hold it is not near the center of mass so a healthy throw
  will naturally get crooked.  Since it has very small tires it needs
  to be taken off from something other than grass.

I'm going to rescue my OS20 and Futaba radio from this and sell it.


              _!_      
Bye        ----O----   
Kay R. Fisher / \     

================================================================================

        Re:< Note 246.14 by 29930::FISHER "Battery, Mags, & Gas Off!" >

        Kay,
        
                We have had a discussion about hand launching before, but
        sounds like you can use a bit of advice.
        
                A controlled hand  launch  is  best given if you give the
        plane speed by a  combination of taking a couple of steps forward
        as you launch the plane  with  a  smooth  forward  motion of your
        hand.  It's amazing how much spped you can give the plane without
        having to throw hard.  Also, don't  throw  it  upwards!  Throw it
        sraight out.  The first time it is  a  bit scary to see the plane
        lose  altitude,  but  it's  able  to gain airspeed easily  of  it
        doesn't have to climb at the same time.
        
                I  have  made  tons  of hand launches this way and  can't
        recall  a  bad one, other than the ones with a Scooter  II  built
        without ailerons! But that's another story.
        
        Anker

    After reading about the trials and tribulations of the budding novice,
    Kay Fisher in the earlier notes, I decided that this woulod be the best
    incidence keyworded topic to ask this in.
    
    I'm building a standard class glider which has 3 degrees of incidence
    built in. I'll build it per plan BUT
    
    How is the proper incidence for a given model determined and has anyone
    built a plane with adjustable incidence and played around with it in a
    semi-scientific manner? What does the incidence buy you that changing
    the CG with a 0-0 planform doesn't. I've read the dynamic balancing
    notes. At what point do you stop moving the CG and start changing the
    incidence on a new design?

    Jim,
    Trying to arrive at hard and fast answers to your questions is
    virtually impossible because the type of glider in question and
    its desired performance from both the designers and builder/flyer
    point of view is variable.
    Ideally, from a minimum drag standpoint, the wing and horz. stab
    should be parallel to the airflow in level flight. From a pitch
    axis sensitivity standpoint this is often not desirable. Also
    most glider airfoils are at their best coefficient of lift numbers
    with some small positive angle of attack.
    Combine these two factors and you'll wind up with a built in positive
    angle of incidence and a small negative decalage angle on the
    stab, on most of the milder performing designs such as Oly, Riser,
    G.L. etc.
    
    Some intermediate designs use 0 angle of incidence on the wing with
    a stabilator (Southwind, Algebra, etc.) which allows you to set
    the optimum angle of attack in flight. The Southwind with an E-193
    airfoil has a noticeable nose-up attitude at low speeds. The wing
    incidence has to be increased (by the stabilator) to get adequate
    lift. The Algebra with a S3021 airfoil flies nose-level at the same
    speed, and has less drag as a result.
    Shimming up the leading edge of the wing on the Southwind, easy
    to do because of its wing mount method, brings the nose level in
    slow flight, but then it suffers in top speed because of the increased
    drag.
    Changing the CG to compensate for incidence angles is a no-no.
    You invariably wind up with too much stab deflection in order to
    hold the angle of attack where you want it.
    To summarize:
    Keep the CG range where the designer specifies.
    Changing the incidence/decalage will change the pitch response,
    speed range, and flight appearance (nose up/down).
    The further you deviate from stock, the more unpredictable things
    become.
    Keep in mind what sort of performance the designer wants/expects
    and don't expect to deviate widely from it. If you want different
    performance get a different airplane.
    
    Terry

    As I stated, I'm not intending to change the current plane. I was just
    looking for some insight into the "black art"

    The books and articles by Martin Simon and Frank Zaic are a good
    place to start. I can't quote their titles off the top, but
    something like "Model Aerodynamics" and "Circular Airflow",
    come to mind.