Are these too heavy to fly well?

[frank mccune]

       After hanging in my attic since about 1978. I finally took these three planes out to fly.  Upon seeing one of them fly, my friend said to me." Frank that plane is a canis!"  I agreed that all three planes were to say the least, never going to fly the stunt pattern.  Allow me to describe  these planes and you tell me your thoughts.

Plane one is a green box nobler that weighs 48 oz. and is powered by an older OS .40 S.

Plane two is a Sig Chipmunk that weighs 50 oz. and is powered by an old T&l OS .35 converted to a .40.

Plane three is a Ringmaster Imperial powered by an Enya .35.

     Only the Nobler is capable of doing any maneuvers.  The other go slack on the lines in anything other than level flight.

     Perhaps it is a matter of providing more power/speed to these planes to convert them into stunt machines? If so, I do have some HP .40 engines that will certainly add a bit more power to the equation. These planes fly very well. round and round and in wing overs but...

     If it is just a matter of switching engines, then I have a few Winter projects. 

     Thoughts, suggestions and/or comments.

                                                                                                                       Tia,

                                                                                                                        Frank McCune

[Brett Buck]

       After hanging in my attic since about 1978. I finally took these three planes out to fly.  Upon seeing one of them fly, my friend said to me." Frank that plane is a canis!"  I agreed that all three planes were to say the least, never going to fly the stunt pattern.  Allow me to describe  these planes and you tell me your thoughts.

Plane one is a green box nobler that weighs 48 oz. and is powered by an older OS .40 S.

Plane two is a Sig Chipmunk that weighs 50 oz. and is powered by an old T&l OS .35 converted to a .40.

Plane three is a Ringmaster Imperial powered by an Enya .35.

     Only the Nobler is capable of doing any maneuvers.  The other go slack on the lines in anything other than level flight.

     Perhaps it is a matter of providing more power/speed to these planes to convert them into stunt machines? If so, I do have some HP .40 engines that will certainly add a bit more power to the equation. These planes fly very well. round and round and in wing overs but...

     If it is just a matter of switching engines, then I have a few Winter projects. 

     Thoughts, suggestions and/or comments.

   The weight is not the problem, to first approximation. I presume trim or engine setup issues. The Ringmaster Imperial isn't much of an airplane at the best of times, but the Nobler is certainly capable and 48 ounces with an OS40H is lighter and more power than a few of mine were - and I had no issue getting through patterns at rule book size with it some 40 years ago. I would guess David Fitzgerald's original Chipmunks were probably in the 50 ounce range with the ST46.

     You probably do have to fly them a little faster than a lighter airplane but there should be no problem at all with low maneuvers like round loops, and they should pull very firmly. Have someone time your laps and try to speed the airplane up until you are going around 5 seconds a lap. If it can't get through basic maneuvers like inside and outside round loops at that speed, you have a severe trim issue somewhere (which can presumably be fixed even if it takes cutting it up).

     People spend way too much time weighing airplanes and worrying about the results, the issue is nearly always trim-related, not weight-related.

     Brett

[Dan McEntee]

   I think there are some who post here that would be very happy to have a green box Nobler finish out at 48 ounces! And as stated a Chipmunk should have no problem at 50 if it's in trim and the engine is running properly. If you don't want that T&L OS .35/40, I'll swap you a good FP-40 for it!
   Type at you later,
   Dan McEntee

[Tim Wescott]

Uh, what Brett said.  I tend to run longer lines than conventional wisdom dictates, perhaps because I tend to build heavy.  It lets you go a bit faster for the same lap time, both cutting down on induced drag and giving you more centripetal acceleration.  A 34-ounce Ringmaster S1with a 20FP flies nice on 62' handle-to-canopy lines.  So, if you're desperate and if the engine power is there to sustain it, at least try going longer on the lines than your buddies think is wise.

So -- make sure the engines are running right and the things are trimmed.  I would expect that any one of those should be fit to be at least coaxed through a full pattern, and maybe even be reasonably competitive.

Hunt down Paul Walker's trim articles, and at least go through his first two phases.  Getting the right fore-aft CG, tip weight, and leadout position will do a world of good.

[Brett Buck]

Uh, what Brett said.  I tend to run longer lines than conventional wisdom dictates, perhaps because I tend to build heavy.  It lets you go a bit faster for the same lap time, both cutting down on induced drag and giving you more centripetal acceleration.  A 34-ounce Ringmaster S1with a 20FP flies nice on 62' handle-to-canopy lines.  So, if you're desperate and if the engine power is there to sustain it, at least try going longer on the lines than your buddies think is wise.

So -- make sure the engines are running right and the things are trimmed.  I would expect that any one of those should be fit to be at least coaxed through a full pattern, and maybe even be reasonably competitive.

    I don't know about the Imperial, but the Nobler and Chipmunk can certainly make it through the pattern with good results if weight was the only issue. One of my Green Box Nobler straight out of the kit was 48-49 oz with a box-stock Fox 35, and I made it through at least hundreds of full patterns *at regulation sizes* since I always flew with dimension markers (5 foot high "T" sticks stuck in coffee cans space at 45 degrees around the downwind side of the circle) and always forced the maneuvers into regulation dimensions.

      It's perfectly clear that there *are* problems in addition to the weights mentioned, probably soluble.

    Brett

[frank mccune]

     Hello:

    Thank all of you for the prompt and hopeful replies!

    Yes, the Nobler is the best flying of the three.  I too think that I may need a bit more power.

    The OS .40 Stunt is running much better wit an additional head gasket.  It still needs some work like a prop with less load.  The instructions that were included with the engine suggested 0%-5% nitro and an 11-6 prop.  I think that the 11-6 is too much of a load on the engine due to its poor running characteristics.  This is manifested by the engine going lean as the flight is prolonged.  No matter how much I richen the needle valve, the engine goes very lean and hot!  I do not think that it is the tank.  I have been running it as a standard tank but will check to see if indeed it is a uniflow.  The Nobler flies very well and pulls vey heavily but has this leaning out problem.  I will try an 11-5 or 11-4 prop for the nest flights.

      I have to reattach the fin and rudder as the engine quit inverted and they were both removed upon an inverted landing. This was due to what I think was a flame out due to excessive heat.  A lean run perhaps?  The engine starts out in a great 4 cycle mode and breaks into the famous 2 cycle break while in manouvers but continues to run more lean as the flight progresses.

     Is a fin and rudder necessary on these stunt planes?  My profile planes so not appear to notice that the fin and rudder are missing. Lol

                                                                                                     Be well my friends,

                                                                                                     Frank McCune

[Brett Buck]

    Yes, the Nobler is the best flying of the three.  I too think that I may need a bit more power.

    The OS .40 Stunt is running much better wit an additional head gasket.  It still needs some work like a prop with less load.  The instructions that were included with the engine suggested 0%-5% nitro and an 11-6 prop.  I think that the 11-6 is too much of a load on the engine due to its poor running characteristics.  This is manifested by the engine going lean as the flight is prolonged.  No matter how much I richen the needle valve, the engine goes very lean and hot!  I do not think that it is the tank.  I have been running it as a standard tank but will check to see if indeed it is a uniflow.  The Nobler flies very well and pulls vey heavily but has this leaning out problem.  I will try an 11-5 or 11-4 prop for the nest flights.

     An additional head gasket is not suggested. The venturi might be too large to reliably draw fuel, 5% nitro might not be enough, the prop might be too large, or it may be worn out. Use a 10-6 if you want to reduce the load, and certainly use fuel with mostly or entirely castor oil and a lot of it to avoid overheating. If it has been run lean multiple times it may have been damaged.

     I am confused, you said it pulls heavily whereas above you said it loses line tension as soon as you try to do a maneuver. Those things appear to be contradictory. Also, you said it needs more power, but if it is pulling your arm off it seems to have too much power/speed.

    Brett

[Steve Helmick]

I'd start by giving each plane a good "bench trimming" session per Paul Walker's "Impact" article. Something is wrong with the basic trim settings.

The tank seems suspect in the case of the T&L OS .35S/.40 conversion. Progressive leaning through the run is avoidable by using Uniflow tanks. A cracked or perforated Uniflow tube is not an uncommon cause in tanks with brass tubing. Use copper tubing. All this is assuming that the tank is not permanently installed, which was fairly common 30 years ago. Might need to chop into it/them to make stuff function correctly. I'd suggest doing it, for the lessons likely to be learned.  Steve

[Lyle Spiegel]

Depending on how your cowl is configured, inadequate cooling air flow will contribute to the overheating. As a test, do some flights with cowl removed, and compare. I do not use cowls on my Noblers or Soothie with Fox35 or Vector 40 with B40 or LA46LA. 

[Lyle Spiegel]

Have you done very thorough flushing of your fuel tanks? If they sat empty for long time possible to have loose gunk / oil residue which wil interfere with good flow. Important to install inline fuel filer ( clap trapp is best one since you can quickly identify dirt or gunk particles)

[frank mccune]

     Hi Lyle et al:

     I have removed the cowls from the planes in question to help eliminate the cooling problem.

     I will try these planes with different props and fuels.  Will post results.

                                                                                                     Thanks for the replies,

                                                                                                     Frank McCune

[Scott Richlen]

What props are you using?  There is a big difference between manufacturers.  Maybe try a Xoar.  Also, try lower pitch to see if that will help.

And as others have suggested, check your tanks to make sure they don't leak and are uni-flow.  Are your fuel filters staying clean?