20lb plane with 65cc engine
03-06-2008, 08:37 AM
#26
RE: 20lb plane with 65cc engine
ORIGINAL: Pat Roy
RTK has the Sukhoi I was referring to and it is not short in the vertical. That engine screams with a stock pipe. With a tuned pipe it would take the house down. The fatter wing of a profile would add quite a bit to the slow and level flight performance. Due to that I think the only place you might come up a bit short is in a hover. The rest would be fine. You're going to have to do some serious math to determine if a larger and heavier ZDZ 80 and pipe will be able to be offset by any additional thrust.
RTK has the Sukhoi I was referring to and it is not short in the vertical. That engine screams with a stock pipe. With a tuned pipe it would take the house down. The fatter wing of a profile would add quite a bit to the slow and level flight performance. Due to that I think the only place you might come up a bit short is in a hover. The rest would be fine. You're going to have to do some serious math to determine if a larger and heavier ZDZ 80 and pipe will be able to be offset by any additional thrust.
Exactly what I was thinking Pat. Hovering is going to be pretty lame. Harriers should O.K. as they don't seem to need alot of power. I was just at RC Showcase and the standard ZDZ80 weighs 4.2lbs bare. Anbody know the ignition weight? The exhaust doesn't matter because either engine will get the same tuned pipe. I'll get a weight of my 62 in a little bit.
RTK- the thread is in the profile section. One of my friends from our club jump in and is scratch building a profile also. His is a different design though.
bbagle1- An 80 is my dream. Hopefully I'll be able to pick one up at a decent price. As for the regular vs the Super, I talked with Dick a while back and for the extra hundred, the slight power increase wasn't worth it for my application.
03-06-2008, 11:17 AM
#28
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RE: 20lb plane with 65cc engine
The plane in the vid is near 17 lbs before fuel. The G-62 is RC ignitions conversion and weighs 4 lbs 1 oz. The CF pipe and modified DA-50 header weighs 11.5 oz (if memory serves)
http://www.youtube.com/watch?v=Apz895e8ERw
Ralph says that the 62's like RPM as they are designed to run at 13K. They really do come alive over 7k.
One consideration is that you will be working the engine harder to carry the plane that weighs more and has more drag. As an educated guess you might find yourself using over half throttle most of the time so you will need to keep the engine cool to stay on performance. Also midrange torque will be less with the smaller engine/prop so getting out of trouble in manuvers might need more lead time.
I put an undersized engine on a 35% airframe recently. (Torch 90 on Pacific Planes 102 inch Extra) Power to weight is 1.7 and it will do most anything except multiple upline snaps. Recovery from these type of manuvers are slow and I think it is the lack of torque as the thrust is there.
Have you guys ever seen the vid of the 40% aerobat on a DA-100? It flew like a foamy as the weight was the lowest for that size plane. If you listen to the engine he is running it hard and long for the uplines and majority of the exciting part of the flight.
Good luck with it.
WrongWay
http://www.youtube.com/watch?v=Apz895e8ERw
Ralph says that the 62's like RPM as they are designed to run at 13K. They really do come alive over 7k.
One consideration is that you will be working the engine harder to carry the plane that weighs more and has more drag. As an educated guess you might find yourself using over half throttle most of the time so you will need to keep the engine cool to stay on performance. Also midrange torque will be less with the smaller engine/prop so getting out of trouble in manuvers might need more lead time.
I put an undersized engine on a 35% airframe recently. (Torch 90 on Pacific Planes 102 inch Extra) Power to weight is 1.7 and it will do most anything except multiple upline snaps. Recovery from these type of manuvers are slow and I think it is the lack of torque as the thrust is there.
Have you guys ever seen the vid of the 40% aerobat on a DA-100? It flew like a foamy as the weight was the lowest for that size plane. If you listen to the engine he is running it hard and long for the uplines and majority of the exciting part of the flight.
Good luck with it.
WrongWay
03-06-2008, 01:57 PM
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RE: 20lb plane with 65cc engine
ORIGINAL: Richard D Bahmann aka/Wrongway
The plane in the vid is near 17 lbs before fuel. The G-62 is RC ignitions conversion and weighs 4 lbs 1 oz. The CF pipe and modified DA-50 header weighs 11.5 oz (if memory serves)
http://www.youtube.com/watch?v=Apz895e8ERw
Ralph says that the 62's like RPM as they are designed to run at 13K. They really do come alive over 7k.
The plane in the vid is near 17 lbs before fuel. The G-62 is RC ignitions conversion and weighs 4 lbs 1 oz. The CF pipe and modified DA-50 header weighs 11.5 oz (if memory serves)
http://www.youtube.com/watch?v=Apz895e8ERw
Ralph says that the 62's like RPM as they are designed to run at 13K. They really do come alive over 7k.
