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finally took the stunt trainer out today.

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finally took the stunt trainer out today.

Post  rogermharris on Thu Jul 23, 2015 7:00 pm

well finally after nearly 3 weeks we got out and did some flying.

this was the maiden for the stunt trainer.
i need to figure out how to trim my planes better. this one pulls well flying laps but seems to slack the lines some overhead. as you can see from the video it's a bit nose heavy and it won't turn a small loop. also thinking i need to try moving the leadouts back a bit to help keep the lines tight. there is not much right rudder and i have about 2 degrees of right thrust. most of my planes seem to act the same way. also broke the spiderwire at the handle (the up line) i was attempting to come out on the top of a loop inverted when it broke. cracked it where the firewall mounts to the fuse so it will need some epoxy and it ripped the control horn out of the elevator with a good chunk of balsa. going to cut a new one tomorrow out of c grain. i also need to move my camera waaay back to get the everything in frame.

i know we have discussed different props ect. please watch the video and let me know if you see anything i'm not.

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Re: finally took the stunt trainer out today.

Post  Ken Cook on Thu Jul 23, 2015 7:32 pm

Roger, you can hear the engine working overtime as you climb. Do you hear this from the center of the circle? This is certainly telling a story. The engine is being overloaded. This is not a good sign for maneuvering. As certain flying styles progress, engine condition and reliability is ever more important. Slab wing planes are going to always suffer and the engine is doing it's best just to keep the plane flying let alone stunting. What nitro are you using? That can assist a bit if you up it a little. What prop is currently on that plane? If it's a 6" prop, your going to experience exactly what's happening. Reducing your prop size allows the engine to run it it's higher rpm's which benefits it's stunting ability. Rather than drive in 4th gear, your going uphill in 2nd. Slab wing planes need to be greased into maneuvers. This means a lot of arm movement and little wrist movement. This keeps the speed consistent. If you pull full up elevator into a wingover or a loop without arm movement done properly, the plane is going to be strangled. I would recommend a 5x3 prop like a Cox black. If that's what is currently on the plane, I would try a APC 5x3. These however are expensive and will break easily. The APC 5x3 is around $4. I have to ask what line length are you flying as well. I haven't paid much attention to these posts so I'm not certain if you mentioned it prior.

I'm not a fan of rudder offset or engine offset. However others choose to fly is entirely up to them but I will say that both of these compound the problem of speed falling off. Yes, they work for what your trying to do, but it's speed that the plane needs to fly correctly through the maneuver. Down low, you have line tension, you get up top and the speed falls on it's face.

You must first start with assurance that the plane is flying level correctly. If the wing is flying tip high upright, it's going to come in as you climb.  Next you must not have too little or too much tip weight.  If your confident it's good, moving the leadouts back will cause the plane to fall out of the sky even more. It sounds counterproductive to move them forward, but it is the proper way to gain line tension overhead as your not stalling the plane overhead when the rear end is yawed outboard. The plane should execute the same line tension down low as it does overhead. Again, when you strangle the plane, speed falls off, line tension falls off.
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Re: finally took the stunt trainer out today.

Post  rogermharris on Thu Jul 23, 2015 8:01 pm

thanks ken!  much good information as always!

i am running 25% nitro but have some 30%.  going to order some 35% as well.  i'm running a 6x3 prop at the moment.  sounds like my first plan of action is to go to a smaller prop. if that does not work i can try a blackwidow piston and cylinder for some more power.
from the center of the circle it looks to be flying level and looking at the video it seems that way as well but it does seem to come in as it climbs so if the prop does not get her performing better i will play with the tip weight and take the right thrust out as well. one step at a time....
i am not tuned into listening to how they run during maneuvers so that is something i need to start paying attention too. thank you for pointing that out.
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Re: finally took the stunt trainer out today.

Post  Ken Cook on Thu Jul 23, 2015 8:57 pm

Roger your 25% is a good choice. It works well and is easier on plugs. I would stick with that. I wasn't certain what you were using. The smaller prop though will certainly make a difference and a Black Widow or Sure Start will certainly give good performance. Ken
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Re: finally took the stunt trainer out today.

Post  rogermharris on Fri Jul 24, 2015 8:39 pm

Well I brought the plane in this evening to access the damage. Since i decided to replace the elevator I figured I would also replace the stab as well.
It will be 1/8" c grain this time around. It's a bit nose heavy so I figure that will help as well. Also cracked the firewall in half so that got some epoxy.

Funny thing and of coarse I feel pretty stupid about is I failed to attach the tip weight! That would certainly explain some of what was going on... dough!

I had intended to run a 5x4 prop on this plane and had one on the engine that I had intended to use before being talked into running an external tank but once again my fault.... don't have any 5 x 3's so I ordered some but guess I can also cut a 6 x 3 down and see how that does as well. As a kid our choice for stunting with a black widow was a top flight 5 1/4 x 4. Loved those props! Took a beating without breaking.

My flying partner is off to camp for a week this coming Sunday so I will once again not be able to get out for at least a week so I have time to make repairs.
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Re: finally took the stunt trainer out today.

Post  RknRusty on Fri Jul 24, 2015 11:23 pm

You may find the 3p prop turns much tighter loops. I surprised me, but that was before I understood much about props. For cutting, I like the Master Airscrew props. They break a little easier, but they run good on 1/2A. 5-1/4x3 is my favorite for snatching small planes around the sky.
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Re: finally took the stunt trainer out today.

Post  rogermharris on Sat Jul 25, 2015 11:29 am

RknRusty wrote:You may find the 3p prop turns much tighter loops. I surprised me, but that was before I understood much about props. For cutting, I like the Master Airscrew props. They break a little easier, but they run good on 1/2A. 5-1/4x3 is my favorite for snatching small planes around the sky.
Rusty

?? i'm guessing higher rpm but less forward speed give a tighter loop?
i have a bunch of winsor props but they break with even a hard landing.
i ordered some 5x3's and will have to source some master airscrew props.
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Re: finally took the stunt trainer out today.

Post  larrys4227 on Sat Jul 25, 2015 12:36 pm

rogermharris wrote:
i ordered some 5x3's and will have to source some master airscrew props.

Brodaks has Master Airscrew 6x3's .... trim 'em down to whatever you like. I've got an order in now, because I don't like the flimsy 5x3's I have.
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Re: finally took the stunt trainer out today.

Post  rsv1cox on Sat Jul 25, 2015 5:35 pm

Alright Roger. Anything you can walk away from and fix with epoxy are my goals... Smile

Locking away Ken's advise for my first flight with the Bipe.

Bob
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Re: finally took the stunt trainer out today.

Post  rogermharris on Sat Jul 25, 2015 7:00 pm

rsv1cox wrote:Alright Roger.  Anything you can walk away from and fix with epoxy are my goals... Smile  

Locking away Ken's advise for my first flight with the Bipe.  

Bob

yea... i got the firewall epoxied back on last night and decided since i was replacing the elevator that i would also cut the sab out and replace both pieces with 1/8" c grain. hopefully tonight can start doping up the pieces and will attach them to the plane after paint. maybee this time i will remember the wing tip weight lol!

my boy will bee away at our baptist summer camp for the week so i have no one to launch for me Sad
hopefully i can get it back together and make some more progress on the veco scout
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