Conference vmszoo::rc

    I think if it was tail heavy, you would be having control problems, not
    just constant climbing.
    
    Could need some down thrust in the engine. Most trainers do.
    
    Stab incidence could be off. Changing the wing incidence wouldn't
    necessarily change this. Negative incidence in the stab is like MASSIVE
    up elevator.
    
    I would think that not sanding the leading edges of the horizontal and
    verticle stabs would create a turbulated (rough) air flow over the 
    control surfaces. I "think" about the only effect this would have
    (not counting lifting stabs) would be mushy control response. Could be
    wrong, but that's what it seems like to me.

    Regarding the last reply, you are absolutely correct. I have a home
    brewed screaming idiot srt of plane and left the leading edges flat.
    The plane controlled ok, but not real snappy. I wanted better response
    and rounded off the leading edges,also sealed the hinge gaps and it
    made a very noticable difference. I also agree with the stabilizer
    incidence being off causing the ballooning. If the engine downthrust
    was not enough, you'd not really notice it so much except for
    excellerating. Check that the wing and stab are both at zero incidence
    is a safe approach.

    RE.1
            Actually, I am having a hard time with controll at low
    speed but this is probably a result of the plane being heavy to
    begin with. I get nervous landing a plane at high speed which is
    most likely the way you have to land a dura plane. Im sure he'll see
    this note and check the incidence of the stab as well as adding some
    down thrust to the engine. Thanks for the ideas and keep'm comming
    if you think of any more.
    
                                                                Jim

        Try shimming the leading edge of the stab with a layer or two of
        adhesive tape and see what happens - if things settle down then
        you're on the right track with the incidences.
        
        Andy
        

    what do you do when....
    
    
                  Im about two hours away from finishing my sig cub.
    Before covering, I placed all the gear inside, set the cowl on the
    engine, lay the struts on the wings, you know. Well, now that it's
    all covered up, I lifted it at or very near the CG. and sh*t, it's 
    tail heavy. Im gonna pick up a heavy hub and some stick on some
    lead to get it balanced. Do most cubs come out tail heavy? Here's
    another question. I need some ideas as to how I should attach the
    strut supports. I know there just cosmetic, and most of the pictures
    I've seen and the models I've looked at in stores, don't have them,
    but I'd like to attach them. Any ideas?
    
                                                          Jim

    It is not unusual for a cub to be tail heavy...  Many "scale" models
    are since, in the real thing, the proportionate weight of the engine
    is much more than the scaled up tail surface.  In addition, you aren't
    adding pilots and baggage either.
    
    You do bring up a good point though..  Don't balance an uncovered plane
    and expect it to stay in balance after the covering.  The weight of the
    covering along with the location of most of the covering (most of it 
    behind the CG) will cause the CG to move.  So plan on it and make sure
    you are nose heavy before covering.
    
    Is this a Sig or Goldberg Cub?  You said Sig, but then you said that 
    the struts are just cosmetic....  I know for a fact that Goldberg's Cub
    struts are just cosmetic, but I believe I have been told that Sig
    struts are functional/required.  The wing is not strong enough without
    the lift struts in place.  If this is the case, then you want to make
    sure that your attach fittings are very sturdy.  I would recommend
    looking at the Proctor brass fittings.  They have a number of fittings
    and many of them can be bent up a bit to do whatever you need.  This
    will probably require a bit more setup time at the field.
    
    If you truely believe that the struts are not functional, then you 
    could use the Goldberg plastic fittings.  I have the plastic fittings 
    glued into my (Goldberg, non-functional) struts.  These fittings have 
    "snap on" ends which attach to screws which are left in the wing and
    fuse.
    
    Cheers!
    jeff
    

    To clarify the strut issue, it is a sig cub and yes, the struts are
    funtional, you cant fly with out them. Im refering to the small wire
    strut braces that run from the struts, straight up into the wing. I
    wasn't surprized to find it tail heavy, I knew all that covering
    behine the CG. would effect it, thats why I mounted every thing as
    far forward as I could, just thought it would help more than it did.
    
             --------------------------------
                   ->  |  brace
                       |
    
                      
                                                           Jim
                       |              

    Ah, I understand what you mean by "strut support" now..
    
    I don't have them on mine, but one option would be to just
    attach them to the strut and just have them touch the wing.  I think
    this is how others do it.  From a couple of feet away, you can't
    even tell that the wing end is not attached..
    
    If you really want them to attach to the wing, I would use a tab/slot
    approach (but this may be too late since you are already covered..)
    where the strut slides into a fitting on the rib.
    
    In your first note, it sounded like you attempt to get the CG where it
    was supposed to be before you covered it.  So, uncovered, where was
    the CG in relation to the published CG??
    
    FWIW, back in one of the covering notes, Al Ryder and others discussed
    the various weights of the different coverings..  It is surprising just
    how much that stuff weighs!
    
    cheers,
    jeff
    

    Well, I think I solved the balance issue. I went out and bought a
    heavy hub and a package of stick on weights. I added the heavy hub and
    checked the balance, still tail heavy. Layed both strips of weight on
    the nose, she hung just about perfect but come on , this is alot of
    weight. I looked at the CG. on the plans again and noticed there is
    actually two points of balance. One near the leading edge ( reading
    the manual, it states you should balance the plane with a forward
    CG. to aid the beginner in his/her first flight, moving it rearward
    as experience is gained) and one just below the main spar. If I 
    balance it at the spar, the heavy hub and 1/3 of one weight has it
    hanging a tad nose down. This is the first time I've seen two CG.
    locations on a plan.
    
                                        Thanks for all the input, Jim

    I can't imagine a CG that is near the leading edge (except for our
    friendly Gremlin! :-)  Near the spar is the usual place for CG...
    Heavy hub plus a little bit sounds reasonable.
    
    Bring it down to the local field and have one of the instructors take a
    look at it.  Be sure to bring the plans along to..  And, you might as 
    well bring some of that extra weight!
    
    Cheers
    jeff 
    (Who should take have stock in heavy hubs since they are on all of his
     planes!)
    

    Typical trainer balances on the main spar. If that's where you are, it
    will fly fine. Remember to balance with the tank empty. You can also 
    move the engine forward if there is room left on the mount. Moving the
    engine forward a half inch will probably allow you to get rid of the
    1/3 lead weight.

    Now I see this is a Cub. It should still balance on the main spar.
    I didn't see any mention of what engine your planning on running. A Cub
    should have plenty of room to move the engine forward. Make sure
    receiver battery, receiver, tank, servo's are as far forward as you can
    get them. Should be enough room to put the RX pack under the tank.

    Today, weather permitting, the cub will make it's maiden 
    flight. The sig cub needs a .19 to .35, I have the .35. The
    battery is under the tank, the receiver is just behind the
    battery, the three servos are mounted above and slightly behind
    the receiver. I'll report how everything went if anyones interested.
    
                                                        Jim

>                     <<< Note 1679.13 by CSLALL::ONEILL >>>
>                           -< cleared for take off >-
>
>    Today, weather permitting, the cub will make it's maiden 
>    flight. The sig cub needs a .19 to .35, I have the .35. The
>    battery is under the tank, the receiver is just behind the
>    battery, the three servos are mounted above and slightly behind
>    the receiver. I'll report how everything went if anyones interested.
>    
>                                                        Jim

I'm interested - keep reporting.
I have a little SIG Clipped wing cub.
I just have the strut supports going thru holes in the wing and soldered
a couple of washers on the music wire at about the right position.
The strut support just floats in the holes in the wing.  And falls out
when you remove the struts (rarely).

I used nylon clevis connectors to fasten both ends of both struts.
After 50 flights or so I have replaced a couple on the fuselage end
of the strut where I have a little stress because they are very
close together.

I have a OS .40 Surpass in mine and don't remember adding any weight
tho I may have put a heavy hub on.  CG is around the main spar.
It is not unusual to show a CG range.  I had to change my down
thrust a couple of times before I liked the way it flew.  2.5 degrees
would be a good start.  If you notice it climb a lot when you throttle
up keep adding down thrust till it don't.

Good luck - they are great planes.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
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    Well, due to a brain cramp, I didn't fly friday. In all my
    excitment to get airborn,making sure I had everything I'd need,
    I neglected to replace the preasure tap on the muffler. I did
    however try to get her running. It took a little doing but she did
    fire for a short time, until I brought the throttle down and I 
    counldnt restart it after that which leads me to my next question.
    First, let me give a little history. The engin is a O.S. .35 FP.
    about ten years old. It was involved in a minor crash when it was
    about a year old. I replaced the con rod, it apeared bent, and cleaned
    it all out. I then installed it on a falcon 56. It would constantly
    lean out no matter what I did. I figured the engine was no good so I 
    bought a O.S. .40 FP. The new engine experienced similar problems
    till I reworked the front end of the plane, cutting out the plywood
    mount and installing a dave brown mount with the thust line slightly
    lower than it was before ( I always felt the tank was too low in 
    relationship to the carb.) This help'd alot and I flew the hell out of
    it. Thinking tank position was the problem with the .35, I installed
    it on the cub. I noticed saturday that the fuel won't stay it the line,
    after priming, once I remove my finger from the exaust. The engine is
    inverted, all the lines are new, and the tank center line is inline
    with if not a little lower than the needle valve. Im running 5% nitro,
    a 10x6 prop and Im out of ideas short of buying a new motor. 
    
    
                                     what do I do now?

Make sure the carb is sealed where it is attached to the body of the engine. 
 Sometimes the O-ring is not in good contact and air can leak thru.  I would 
suggest that if the O-ring is 10 years old you replace it anyway.

-Joe

    RE "I neglected to replace the preasure tap on the muffler."
    
    In what sense did the pressure tap need to be replaced. Was it leaking,
    missing, what????????
    
    Virtually no FP engine will run right without muffler pressure. If the
    pressure tap was missing completely, I'm not surprised at the result.
    Basically all your doing is burning off the prime, and then you have a
    dry engine. Get the muffler pressure back and I'll bet the engine will
    run fine.
    
    Also, you might want to check the engine manufacturers recomendation
    for prop size on the 35. A 10x6 prop is a typical "40" size prop and
    might be too much for the 35. The people I fly with are running 9x6
    and 9x7 props on 32's wich is generally "more" powerful than the
    40FP'S. You might want to consider dropping down to a 9x7 or maybe
    a 10x4.
    
    Steve

    Sorry, I'll explain further,
    
    
                       I had planned to use a tatone in cowl muffler
    on the engine (the engine is inverted) so I had the tap installed
    on it, but it was much to much of a hassle putting it on so I switched
    back to the original muffler forgetting to replace the tap when I did.
    I have some 9x6's I can try. Sure would be nice if thats all it is.
    
    
                                                           Jim

    I can "almost" guarantee the missing muffler pressure tap is your
    problem. Let us know how it runs when it's replaced.
    
    Steve

    The tap was reinstalled, and as stated earlier, I tried running it
    with a 10x6, no good, kept quitting. Fuel won't stay in the line after
    priming. 
                              ?????????????????????????????
    

    Well, I don't know where I missed that the tap had been replaced, but
    anywho.........
    
    Check to make sure the muffler pressure line is not kinked or blocked.
    Check the brass pressure tube on the tank to make sure its not blocked
    or kinked. 
    Connect the fuel pump line directly to the nipple on the carb and start
    pumping. If that is clogged, you'll know it, and you may blow it out.
    This may sound stupid, but make sure the needle valve is open. I've run
    across several occasions where people were pulling their hair out
    trying to start an engine and the needle was fully closed.
    
    Basically, either the tank isn't "pushing" fuel, or the carb isn't
    "drawing" fuel. Concentrate your efforts on those things.
    
    Steve

    Steve's on the right track!
    
    Make sure the high speed needle is open, add a a full turn or two to
    make sure.  It is also a good idea to remove the high speed needle
    completely and make sure that there no debri blocking the main jet.
    
    Also, even though the pressure tap is in the muffler, make sure it is
    clear.  I once replaced a tap and loctited it in.  In doing so, I
    unknowingly clogged it up with loctite.  It took me 30 minutes to
    figure out what happened.  Frustrated the heck out of me!
    
    Good luck! 

    I just read my previous reply and concluded that I can't think and type at
    the same time.
    
    Sorry for the grammatical errors.

    Have you double checked that the vent and the feed line aren't reversed ?
    
    Wayne.

     Yes, I checked the lines, all seems well. I switched to the 9x6 prop
    and gave it a shot last night. It ran a little better but still
    quit after about 50 secconds and the heard and muffler are real hot.
    Im gonna try the trick I used on my buddy's ship and go to a higher
    nitro.
    
                                                      Jim

    Well,
              I tried the higher nitro ( I was using 5%, switched to 15%)
    re-adjusted the air bleed screw, and I got her idle o.k and run up to
    high speed with out hesitation. Now I just gotta wait for a decent
    day and I'll see how she flies.

    I hope Im not beating a dead horse. I did a dir/title= to find
    a note dealing with rudders but nothing turned up. Im still a little
    puzzled about the use of rudder to turn a big airplane like a
    piper cub. My ailerons probably have more gap than I should and
    I may try to seal them up in the future but for now, why can't I
    fly this cub like any other high wing, flat bottom ship. I had
    problems last time out durring take off. As she broke ground, she
    started rolling left. Normally, I'd level a plane out with ailerons.
    This time I had to kick in rudder till she got some altitude. To make
    nice gentle turns, Im moving both sticks in the same direction.
    Guess I should have learned to fly with rudder long ago and not
    rely on the ailerons so much.
    
                                                    Jim

    re: -.1 
    
    Call me at dtn 445-6577 for an explanation about rudder and the many
    variables that it affects and that affect it.
    
    Chris
    

    Your cub has a scale wing, not really flat bottom. One of the things
    that usually "bites" people flying cubs is just what you describe. At
    low airspeeds, the ailerons are pretty much ineffective. You HAVE to
    use rudder to keep the wings level. This is true for landing also. At
    altitude, in normal flight mode, having gaps between the ailerons and
    trailing edge "will" decrease the response, but again, what you are
    seeing is more related to the "scale" design of the cub than gaps in
    the ailerons. As you have seen, making coordinated turns (using BOTH
    aileron and rudder) is the way the cub likes to fly. Same holds true
    for the real thing. Keep that left thumb in shape and you'll be fine.
    
    Oh ya, one more thing. The roll too the left is because of the torque
    from the motor. Once it breaks ground, the plane will tend to roll in
    the opposite direction the prop is spinning. Again, correct with
    rudder.
    
    Steve

Don't know where in this file the discussion is but you might try searching
for "aileron/rudder coupling".  

Everything Steve said is right.  An interesting thing happens when
planes get slow with a high angle of attack.  This would be Cubs
landing or any plane that is under powered.  As the wing is near
stall speed when you add aileron control the wing that has the
aileron go up is similar to adding washout - so it won't stall.
The wing that has the aileron go down is like adding washin - and
it stalls.  So the stalled wing drops and you get an interesting
effect sometimes called aileron reversal.  So you could consider
lack of aileron response at slow speeds as a warning indicator that
you are nearing your stall speed.  The natural reaction is to slam
the ailerons to the limits when a wing drops.  This just makes the problem
worse and a classic snap roll / crash quickly follows.  Happens
mostly on down wind turns where the pilots judgment of true air speed
is way off.  

So your going down wind getting ready to land.  You turn left slowly 
on base, turn left again on final and the left wing drops a bit.  You
give some right aileron and faster than you can say Montezuma Montana
your SIG Clipped Wing Cub is balsa dust.

Welcome to the club.

Bye          --+--
Kay R. Fisher  |
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    I'd like to thank you all for the reply's and you Chris for the phone
    conversation. I was told early on in my venture through R/C flying
    to learn to use the rudder but never found the imediate need for it
    with the exception of manuvers like snaps and hammer heads. No that 
    Im breaking into more scale like ships, learning the use of rudder
    will become a priority.
    
                                              Jim

And then the next step is choppers where you REALLY learn how lazy your left
stick is. Of course, few of my rudders have ever been THAT responsive

(another) Jim

    Jim Reith is right... heli's will make you use that left hand.  Notice
    that I said HAND not THUMB.
    
    This tip is for anyone using their thumbs to fly:  
    
    1st Use a neck strap or tray.  This helps stabilize the transmitter.
    
    2nd Grasp the sticks (both of them) using your thumb and forefinger.  
        This will feel awkward at first and maybe even seem difficult. 
        Give it a shot for several flights and you'll find it will improve
        (and smooth out) your flying abilities.  Again,  it will be 
        uncomfortable at first for some due to the increased sensitivity. 
        Take your time and work in to it and it will just happen.    
    
    The more uncomfortable you are with this, the more you will likely
    improve your flying skills.  
        
    Let us (RC Noters) know how you progress.
    
    Chris