2948 Kawasaki Ki 61 Prototype

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mlapacz
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2948 Kawasaki Ki 61 Prototype

Post by mlapacz »

I got bit by the scale bug since I saw the guys flying scale at the NATs this summer.
It was fun choosing a plane, using CAD to scale the drawings, and cutting out the parts with my hot wire bow.
I haven't flown it yet because the temp this weekend was in the 20's.
I was surprised that the plane's finished weight was 2# 14 oz. I usually tend to build on the heavy side.
I guess I'll have to add more bidi tape on the next one to get it up to the minimum 3# 4 oz.
Can anyone explain the reason for the rules stating a minimum weight instead of a maximum weight?
Lighter planes will launch and fly better. Heavier planes will cause more damage from mid airs.
Anyway, I learned a lot building my prototype and should have a fleet ready for next year.
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Mike LaPacz
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Re: 2948 Kawasaki Ki 61 Prototype

Post by Blue Note »

mlapacz wrote: Can anyone explain the reason for the rules stating a minimum weight instead of a maximum weight?
Lighter planes will launch and fly better. Heavier planes will cause more damage from mid airs.
That is currently a topic of much debate and criticism and your observation is absolutely accurate in all regards. Right now and simply put, if we want to compete in a RCCA contest, we are obligated to build our planes in accordance to the currently agreed upon rules of each individual class...whether we agree with them or not. That being said, good work on the plane.
Chris Gunter
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Re: 2948 Kawasaki Ki 61 Prototype

Post by Dr. Kamakaze »

Mike,
Looks great! It never fails that I build a prototype during the cold weather too. Let us know how it flies when you find a mild day.
Way to go designing it from the ground up!
Andy Runte, aka "Dr. Kamakaze"
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Andy "Dr. Kamakaze" Runte
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mlapacz
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Re: 2948 Kawasaki Ki 61 Prototype

Post by mlapacz »

I got the chance to maiden the Ki 61 today.
The temp was 39, with a light breeze out of the south.
All I have is an old, and tired, ASP 25 to use at this time.
I was only able to get 8900 RPMs out of it.
This is the first time I've flown a new plane and did not have to make a trim adjustment.
I will reduce the aileron throws a bit because it was a little wild on the launch.
I think a stronger engine would have helped also.
I'm very happy with the design and will make more for next year.
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Mike LaPacz
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Re: 2948 Kawasaki Ki 61 Prototype

Post by Bruce B »

You were only getting 8900 rpm out of it? Sounds very tired. I'd check to make sure the tach wasn't set for a three blades prop. If it flies good at that rpm it should be sweet with a stronger motor.
As I understand it, the guys that pretty much wrote the rules wanted it to be more of a pursuit type class rather than just furball. They did a whole lot of building and testing to get to where we are today. That's the main reason for the high minimum weights. Keep the wing loading up so you can't just keep turning. I'm all for max weights vs minimums. I'm all for doing away with the rpm rule as long as you keep the stock carb and muffler. Not everyone has an engine that will turn 14,500 anyways.
The green and red look good together. Nice plane and welcome to the scale world.
Bruce Blevins
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mlapacz
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Re: 2948 Kawasaki Ki 61 Prototype

Post by mlapacz »

Bruce,
Thanks for the insight into the minimum weight requirements in the rules.
I checked my tach and it was set correctly to a 2 blade prop.
The engine is pretty sad, but it did pull the plane around well enough.
I've got the parts cut for 2 more planes and should complete them by spring.
I'm looking forward to flying some scale with you next summer in Muncie.
Mike LaPacz
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Re: 2948 Kawasaki Ki 61 Prototype

Post by Hat Trick »

Minimum weight is to keep everyone even and more survivable. A really light plane will eat up a heavy one. It won't take any kind of a hit though.

Lower wing loading means better performance in the turns and combat is won and lost in the turns.
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Re: 2948 Kawasaki Ki 61 Prototype

Post by Bruce B »

You don't have to wait till summer. We will fly scale at the lone star nats in March. Be glad to see some of the northern guys make the trip
Bruce Blevins
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