Conference vmszoo::rc

    
    Taking weight out of the tail is always your best bet, you'd
    have to add three times as much weight to the nose and you
    don't want to add weight if you don't have to.  Given that it's
    all covered, I'd recommend you try one of those heavy prop nuts,
    they fit under the plastic spinners.  I had to use one to
    balance a Super Sportster .20, and the weight gain didn't
    seem to affect it much.
    
    If you can't get it to balance with the nose weight, I wouldn't
    give up and try to fly it tail heavy.  You'll spend more time
    repairing it than it would have taken to remove weight from the
    tail.  Balance it right and it will fly great - Charlie Watt's
    got one and it's a beauty.
    
    Bill

    Wow... nice to know I'm not the only one who built a tail heavy
    sportster 40!!!  
    
    This is what I did since I used an aluminum spiner and couldn't use a
    heavy nut... I used the lead strips with the "sticky" back and 
    figured out the the approprait amount to add by placing the cut
    strips inside the engine compartment.  I then removed the engine
    and glued the lead strips under the engine mount... presto!  you
    can't see the weight!  The sportster has such a nice nose, you
    wouln't want to have to look at those ugly weights!!
    
    This is a valuable leason, or it was for me.
    	a. ALWAYS check your CG before flying
    	b. With a long tail moment, just a bit too much weight at the
    	   tail can take a lot of lead in the nose.  My guess on the
    	   sporster is that the ratio is about 4 to 1 or so.  One
    	   once on the tail's end takes about four in the nose!
    	   Hence, go easy on the glue when working the tail!!
    
    Good Luck, the sportster is a "great" plane to fly.  I'm sure 
    you'll have fun with yer new bird!!! 
                                        
    /Brian
    
    P.S.  Try to get the weight as far forward as possible!  It'll take
          less weight to ballance!

    pss 346.3
    
    I had to add 5-6 oz to my sportster... makes ya "krindge" after
    being so careful elsewhere!  You'll be surprised how little
    lead will do the trick(volume wise)
    
    /Brian

    
    Suggestions;
    
    		Use a metal engine mount. Install battery above or below
    fuel tank.  
    
    					Tom

 


   Good suggestions...I think I've got it...


    
    Mounting the  battery  under  the tank was thought of before,
    but since the fuel  compartment is fully enclosed by the nose
    structure it was ruled out, and it already  has  metal engine
    mounts.   However, if I'm going to have to  either  'unbuild'
    the tail, unbuild the nose structure, or add weight, I'll  do
    a little of each.
    


    It will be easier to carve out  the  bulkhead  seperating the
    fuel compartment from the radio compartment, than redoing the
    tail section.  I  didnt  like  the  arrangement  when  I  was
    building  it, but I decided to follow the plans.  I'll  check
    the  plans  to see if there is enough room under or over  the
    tank. If there is, this  arrangement  will  give  me  a   few
    advantages over re-doing the tail.
    
        1) If I ever have fuel tank problems I  will  have access
           to it.
           
        2) I  can  then  move  the  battery under the fuel  tank
           to help solve the CG and ofset the balsa I removed  in
           the process.
           
        3) It  will  give  me more room in the radio compartment
           (boy  is  it  cramped!) to move the servos forward and
           secure the receiver better than the way it is now.
           
        4) I probably  wont  need  to add wieght, or can get away
           with only a metal spinner or prop nut.
           
        5) I wont have to do any re-covering.
        

     When I built  the  plane, I was very careful not to use alot
     of glue anywhere.   I  mainly  used  CYA  except  the engine
     section,  wing joining, and a  small  amount  for  the  tail
     feathers.  I was sure that  if  anything,  it  would be nose
     heavy.
     
     Has anyone built a SS40  that  balanced  out reasonably well
     from the beginning?  I've built a few other planes, and they
     have always been fairly close in balance  when  I  was done.
     This guy is just too far off, and  I've  done  everythng  to
     spec! 
     
        Thanks..
        
                Steve
                

    
    I know what you mean about tail heavy SS-40s...  Mine is only a
    hair nose heavy, but I am using an old K&B .60..  If I used a .40,
    I'm not sure how it would balance out...
    
    2 ideas...
    
    1) They make 1,2, and 3 ounce weights that can be used as prop washers,
    between the prop and the prop nut.  Pretty slick, although I am
    not sure how it would fit under some spinners.
    
    2) Lead shot, like that from a shotgun shell.  Measure the right
    amount of lead, mix up with some epoxy, and pour it into the engine
    compartment (remove the engine first.  This stuff will flow around
    and fill all of the little nooks and crannies.  Problem here is
    that you are pretty much comitted, once the stuff sets up.
    
    Cheers,
    jeff

    Steve,
    
    Don't want to get ya down, but my bat. pack in the SS40 IS under
    the tank, and I still had to add nose weight.  I think I read you
    correct, but is the tank not accessable from the radio compartment?
    Mine was... I used an 8-oz Tank, and the battery pack slip right
    under the tank, but it wouldn't fit right up against the firewall
    due to the shape of the nose.
                        
    Lots of luck,
    
    /Brian

    try a bigger engine (eg make sure its heavier too). you also get
    a bonus: more power
    
    md

    My SS40 came out only slightly tail heavy.  I was very careful to
    minimize the weight at the tail because I had already built a SS20
    which came out tail heavy also.  I also moved my engine out as far
    as possible toward the front to get some leverage.  I am now flying
    it with a 2 oz higley prop nut, but I think that it is too stable.
    Now that it has flown, I am planning to remove the heavy nut.  
    	I would take the time to improve the balance without just adding
    weight.  The end result will be a better flying plane.  It never
    pays to rush the final sorting out process.  
    	The other thing to be sure of when balanceing the SS40 is to
    balance the plane around its centerline.  Do this with engine/muffler
    installed.  If you don't do this, you will end up with trim problems.
    I had to add a couple of washers out at the wing tip on mine.
    	Do put the battery pack under the fuel tank if possible.  I
    had to buy a flat pack for my SS20 to get it to fit.
    
    	Good luck! I am very happy with my SS40 and my SS20.  I have
    an OS40FSR in my SS40 and an OS25FP in my SS20.
    
    Charlie
    

    
    	FOR ANYONE THAT IS GOING TO BUILD ONE OF THESE, CUT LIGHTENING
    HOILE IN BOTH STABS. ALSO IF YOU TRIM OFF APP. 3/8 OF AN INCH FROM
    THE TAIL MOMENT (MAKE THE TAIL END OF THE FUSE 3/8" SHORTER" THIS
    SHOULD ELIMINATE THIS TAIL HEAVY CONDITION THAT SEEMS TO BE DESIGNED
    INTO THE PLANE.
    	NO OFFENCE MENT (EXCEPT TO THE DESIGNER) BUT THERE IS NO EXCUSE
    FOR THIS CONDITION.
    
    						TOM

    
    RE: .8 and .10
    
    Hummmm, it seems that both of you have access to the fuel compartment.
    I checked the plans last night, and it showed a solid ply bulkhead
    installed between the fuel and the radio compartments. I ran through
    the instructions and didnt see anything about creating an access hole
    or modifying the bulkhead at all. Did you modify this, or did Great
    Planes change the design and/or plans since I purchased mine? 
    
    It also seems that I wont have enough room to install the battery
    in the tank compartment. I like long stick time, so I changed from
    the recommended 6oz to a 10oz tank (my cub has 16oz and I can fly
    for 30-40 minutes at a shot!).
    
    It seems that either way I look at it, I'm going to have to lighten
    up the tail and add some weight (how depressing!).
    
    Thanks for the help...

    

    I went with an 8 oz tank in my SS40.  I agree that you will not
    fit the battery under a 10 oz tank.  In my kit, the bulkhead is
    cut out.  Yours must be, because your tank would not fit totally
    within the fuel compartment anyway.  I made my tank easily removable
    for servicing.  I also made sure that I got the tank well isolated
    in foam to keep vibration from foaming the fuel.  In addition, I
    made the holes in the firewall large enough to allow for silicon
    insulation around the brass tubing to vibration isolate it.  Be
    careful not to crimp the tubing or to hard connect it to the firewall
    or you might experience cracking of the tubing after extended use.
    This unpleasent experience happened to a friend I fly with in his
    SS20.  He filled up the front of the plane with fuel, creating a
    mess.  To protect against this further, you should always seal
    the balsa in the fuel and radio compartment with balsarite or
    equivalent to prevent the wood from being ruined if you get a leak
    in the fuel system.
    
    

    
    Dan,    I don't think that Great Planes kits have a common design
    flaw that makes them tail heavy.   I know that I always talk about
    pattern ships but did you ever look at one?  They have excessively
    long tail moments that could contribute to a tail heavy condition
    yet they come out ok every time.  What I think is needed in general
    is a lot of preplanning prior to adding any glue to balsa. Also
    looking for ways to lighten up a structure without reducing it's
    integrity. This will get you and others out of the problem of
    building tail heavy planes. 
    	    As an example I usually add a platform of balsa sheet to
    every tail section across the two fuse sides to support the stab
    and still the planes aren't tail heavy.
    
    
    					Tom

    
    RE .21 - Nope, they're not all that way - I did a check of the
             CAP 21 this past weekend and it's coming out perfect
             so far - with the servos, receiver and battery behind
             the CG.  I plan to stay flexible with servo, receiver
             and battery locations until the plane is covered, because
             the covering tends to add more weight to the tail than
             to the front.
    
             If the kit was designed to balance with Monokote and a
             nosewheel, the fact that you glassed and painted and used
             a tail wheel might be part of the reason it came out tail
             heavy.  I think another part of the "problem" is that some
             of the kits were designed for heavier engines.  Some of
             the Great Planes kits advertise 4-stroke adaptability, and
             the 4-strokers are heavier.
    
             I don't think you'll notice the extra 4 ounces on that
             plane.
    
    Bill

...
>    I'm beginning to wonder if tail heaviness is a common problem to
>    all Great Planes designs. I just had to add about four ounces to
>    the nose of my Trainer 40 to get it to balance. Of course I compounded
>    the problem by removing the nose wheel and adding a small tail wheel.
...    
It's just Gods way (or Great Planes way) of allowing you to install an
on board ignition.  They made a deal with the Ni-Starter company.
The ends bugger up on the ni-starts and you use the nicad in the front
of Great Planes kits for ballast :-)

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

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

    Dan,
    	A buddy of ours that has a trainer 40 had the same tail heavy
    problem.  He used a light weight OS 35 and he did not pay much 
    attention to weight reduction in the tail.  (He barely sanded it
    at all).  We ended up adding some nose weight and a 2-Oz heavy
    prop nut.  I would highly recommend that you use a heavy prop
    nut to help your balance problem as it gets the weight as far forward
    as possible and it also smooths out your idle.  Another trick to
    help balance without adding weight is to move your engine as far
    forward on the mount as possible.  I helped my friend mount his
    engine and we moved it forward over 1/4 inch over where he had
    first put it.  
    	By the way, don't fly the trainer 40 tailheavy.  It will be
    a handfull on takeoff.  By the way, what engine are you using?
    
    
    Charlie
    

    Dan,
    
    only one minor consideration you should keep in mind regarding the
    use of a weighted prop-nut:  remember that you have all yer' nose-
    weight "eggs" in one basket here...if the engine should backfire
    in flight and spit the prop-nut (it happens occasionally), you'll
    be faced with having to dead-stick a tail-heavy aircraft.  I wouldn't
    use more than 2-oz. on the prop-nut due to this possibility.
    
    I've seen scale-guys machine upwards of 1-lb. prop nuts (hidden
    under the spinner) and lose their aircraft when the weight was lost
    in flight.  Not a frequent occurrence, to be sure, but something
    you should be aware of and consider.
    
    Adios,	Al

    
    	Re: 346.21
    
    	Absolutely not!  I've had the pleasure of building two of Great
    Planes' kits (an SS40 and a Trainer 40) and both balanced out very
    nicely.  On the Trainer 40, the battery is all the way aft in the
    center compartment to make it balance right.
    
    	Both of these planes take .40 FSRs (Bill, what ARE you going
    to put on the SS40 for an engine?) and the heavier engine may account
    for the good balance.
    
    	I also keep lightness and balance in mind throughout the building
    process.  I replace wood that I don't like and adjust my sanding to
    make it come out right.
    
    	Enjoy.

    
>    Both of these planes take .40 FSRs (Bill, what ARE you going
>    to put on the SS40 for an engine?) and the heavier engine may
>    account for the good balance.

    I'm gonna put the Enya 46 4-stroker in it, Z.  Can't wait to use
    that engine upright.  It didn't idle well inverted but on the
    bench it idled well (upright).   I know it's gonna take some nose
    modifications but I think that engine will be a good match for the
    SS40 (it was more than the Citabria needed for sure).

    Bill
    
    P.S. get back to work, don't you have some sort of deadline to meet?

    Al,
    	You have a good point about the possibility of throwing the
    prop nut.  I have not experienced this with my trusty OS 2-strokes,
    but everyone I know with a 4-stroke has had it throw a prop.  It
    usually happens to them when the motor is cold and they adjust the
    mixture too lean.  On planes without much nose moment, it just
    seems hard to balance them if they come out wrong.  I guess that
    the best thing to do is what Fred Z mentioned:  Minimize the tail
    weight during the building and finishing phase since it is much
    easier to add a little weight to the tail or move the  radio gear
    back during construction.  I was fortunate that when I built my
    Super Sportster 20 and 40, Bill Lewis had already experienced
    difficulty getting his balanced.  I tried hard to minimize the
    tail weight, knowing that I would probably have problems.  
    
    Charlie
    

    Charlie,
    
    Yeah! I agree...throwing the prop/prop-nut in flight is a reasonably
    rare occurrence;  I've only had it happen to me twice over the past
    24-25 yr.'s of R/C flying.  Once was when my first O.S. .58 blew
    the rod, bringing the engine to a verrrry abrupt stop and the other
    occasion was when a Webra .60 Blackhead hiccupped in flight for
    no apparent reason and spit all the prop hardware off (it never
    did it again).  BTW, I should note that the original O.S. R/C engines
    were rather lightly built (their only weakness) but that is no longer
    the case...they're as tough/durable as any engine going and more
    so than some.
    
    As you mentioned, from everything I've read/observed, 4-strokers
    are notorious for throwing the prop/prop-nut so a flyer would
    definitely be at risk if he'd placed a significant amount of nose-
    weight in the prop-nut.  As I said, I think more than 2-oz. might
    be inviting disaster, particularly for a newcomer, if the noseweight
    were lost in flight as the sudden resultant tail-heavy condition
    will demand some real heads-up pilotage.
    
    Incidentally, I use a Higley 2-oz. weighted prop-nut on the ol'
    Yeller Peril but I have another 11-oz. of buckshot/resin hidden
    in the inside lip of ring-cowl so loss of the prop-nut would not 
    induce a significant problem.  What I'm saying is, "don't put all 
    yer' eggs (noseweight) in one basket if you can help it."  
    
    Adios,	Al

    Al,
    
    I've not come across the weighted prop nut before (where HAVE I been?)
    and note what you say about "eggs" and "baskets". One noter commented
    that the nut helped smooth the idle - I can understand that, but are
    there any other (beneficial or adverse) effects on the engine when one
    adds weight where it wasn't (apparently) meant to go? I had in mind
    excess bearing wear etc. 
    
    Keith

    
    I was sitting here and realised that this note came abo0ut because
    Dan Snow had added a tailwheel to his ship. First off does anybody
    realize that the addition of three ounces of nose weight can be
    counteracted by reducing tail weight by 3/4 to 1 oz.? 
    
    Secondly I thought someone might be interested in my tailwheel set
    up.
    
    I have never had one fail.
    
    They are not scale.
    
    
    Start by cutting a piece of the yellow control rod app. 1 inch long.
    to this is added a 1/16 - 3/32 wire.. At one end bend a 90 degree
    angle. At the other end bend a 45 degree angle and whatever bends
    are necessary to mount the wheel. Spray the tail end of the fuse
    where the yellow baring is to be mounted with CA accellerator(sp)
    Add a bead of CA to the yellow baring and affix this to the tail
    end of the fuse. Now using CA, glue a strip of fiberglass cloth from
    one side of the fuse over the yellow baring to the opposite side
    of the fuse. A piece app. 2" long does well. Position the rudder
    in place and mark where the wire will go into the rudder. Cut this
    section out sufficiently to fit another piece of yellow control
    rod. The wire from the wheel will sit inside this yellow tubing
    in the rudder. Support thr rudder around the yellow tubing with
    fiberglass similar to what was done on the fuse. DONE!!
    
    
    				  			Tom  

    Re: -.32..., Keith,
    
    Weighted propnuts up to 6-oz. (I think - it might be 4-oz.) are
    available in the U.S. from Harry Higley, the same guy who markets
    smoke system setups.  Weighted prop washers, intended for use inside
    a spinner and available in an even greater range of weights can
    be had from Prather products...I use one (2-oz.) in the spinner
    of the MiG-3.
    
    I can't honestly answer yer' question regarding extra bearing wear
    by experience or even hearsay but logic/common sense would suggest
    that additional wear, proportionate to the amount of weight used)
    probably does occur.  I suspect though that, due to the fact that
    the bearings are far stronger than they need to be, you'd wear the
    entire engine out before you experienced any negative results from
    using a weighted prop-nut/washer.  Just my opinion but I've never
    heard of anyone wearing out a bearing due to use of one of these
    devices.
    
    Adios, Al

    Tom,
    
    I've used a nearly identical tailwheel setup to yer's for years
    and have had the music wire axle actually wear through before the
    setup failed.
    
    I do, however, add one thing that you may use but didn't mention:
    I put a wheel collar (or solder a washer) on the wire strut immediately
    below the tube-bearing which is glassed to the rear of the fuselage.
    The purpose is to prevent tailwheel load/landing shock from being
    transmitted up the wire into the rudder/rudder hinges.  These hinges
    can take a terrible beating from a taildragger setup and I *HATE*
    replacing hinges, so I isolate them from the loads/shocks exerted by the
    tailwheel.  Make sense??                                             
    
    Adios, amigo,	Al

    re .33:
    
    Tom,
    
    Exactly what is "yellow control rod"?

    Re: -.36..., Dave,
    
    I believe "yellow control rod" refers to the inner tubing of a Ny-Rod
    or Gold-N-Rod pushrod. The outer tubing is usually red or blue, depend-
    ing upon flexibility and the inner tubing is always yellow with a "fluted"
    outer surface for reduction of friction with the inner wall of the
    outer (red/blue) tubing.  The inner tube is frequently used as a
    bearing for 1/16 - 3/32" music wire, as in Tom's application as
    a tailwheel strut bearing, strip-aileron horn bearings, etc.
    
    Adios, 	Al