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Thread: Will it fly?


  1. #1

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    Will it fly?

    I recently put 21cc conversion engine on a high wing plane,(too much free time is an awful thing) and am wondering if you guys think it will fly. The wing area is 720 square inches, fully symmetrical, with flaps, and it weighs 9lbs dry. I cut the firewall back 2 inches so as not to have to add any weight to the tail. The engine spins a 16x6apc @ 7200rpm. I believe the plane is an old GP pt-60. I don't expect 3D capability, but am wondering if it will even get off the ground. I plan to maiden it tomorrow, but was hoping to get some ideas as to what to expect . Thanks in advance guys.
    It is better to keep one\'\'s mouth closed, and be thought a fool, than to open it, and remove all doubt.

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    RE: Will it fly?

    Scott, I have similarly equipped trainer type 60 size with an Echo 16cc on it and it gets up quick! The engine is only propped for 6800 rpms but does it's thing well. CDI, no magneto..tried with the magneto, too heavy to do anything. EI is the way to go for conversions if you want to make it work. I cheat on the ignition battery, using 700 MAH nimh AAA cells for a really light weight system. Still gives me about 45 minutes flight time per charge, but with the lighter weight overall, ya can't beat it.
    You never know till you try it, your might be ok at that weight, but at 9 lbs it won't be aerobatic.

    John

  3. #3
    foodstick's Avatar
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    RE: Will it fly?

    If thats the trainer I think it is, I would say it will fly, it won't be high spirited but it should land predictable ..but possibly will land a little hotter than you might think. I would expect a long quick glide.. the conversion motors smaller than 25 cc are usually a bit weak..


    All in all I bet you have some fun with it.

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    RE: Will it fly?

    I have a really bad habit of doing this. I have some nice planes to fly, but I always find myself trying to cobble together some "frankenstein", just to see if it will fly. I occasionally have some great successes, though. I recently shoehorned a Zenoah G20ei to the front of a H9 40 size stick. That one was loads of fun....till it nearly shook the airframe to pieces [:@]. Oh well, we all enjoy different aspects of this hobby. I guess that's what keeps it interesting, at least for me.
    It is better to keep one\'\'s mouth closed, and be thought a fool, than to open it, and remove all doubt.

  5. #5
    av8tor1977's Avatar
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    RE: Will it fly?

    The wing loading is fairly high for that size plane, at almost 29 oz. per square foot. The power loading isn't too bad; you will be getting about 9 lbs. of thrust. It will fly, but let it get some speed up on the take off run before lifting off, and then take it up high and do some stalls so you know what speed you will need to maintain on landing approach. Let us know how it works.

    AV8TOR
    If it is not SCARY, it is NO WHERE NEAR powerful enough!!
    All R/C planes have expiration dates---> It's just not printed on them anywhere!

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    RE: Will it fly?

    Just got back from the field. I was pleasantly surprised. It was more lively than I expected. I took it up high and decided to play a bit. It will roll without falling out of the sky, and it will do a loop...if you get a running start. I hit the flaps and it slowed way down, no bad habits that I noticed. Came in for a nice slow landing, with full flaps. I'm looking foreward to flying this thing some more. It's ugly as all hell, but it is fun to fly...and since it's a gasser, it will be easy on the pocketbook too.
    It is better to keep one\'\'s mouth closed, and be thought a fool, than to open it, and remove all doubt.

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    RE: Will it fly?

    I have a similar plane. I flew my 4-star 60 today. I cut the firewall back and installed a 21cc Stihl conversion. I am running the ignition with a BEC off the main rx power. A week ago I switched over to an A123 2300mah pack. Three flights used 250 mah. It flies really nice. I like that it fits in my Ford explorer without taking the wing off.

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    RE: Will it fly?

    Good Job Scott !

    Sounds like a success..

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    RE: Will it fly?

    ORIGINAL: ScottMcM

    Just got back from the field. I was pleasantly surprised. It was more lively than I expected. I took it up high and decided to play a bit. It will roll without falling out of the sky, and it will do a loop...if you get a running start. I hit the flaps and it slowed way down, no bad habits that I noticed. Came in for a nice slow landing, with full flaps. I'm looking foreward to flying this thing some more. It's ugly as all hell, but it is fun to fly...and since it's a gasser, it will be easy on the pocketbook too.
    Great. Glad to hear that it worked out well. A few hours after I posted a reply, I thought, "why didn't I tell him to mix flaperons on that plane?" Sounds like you already had that covered. I use flaperons even on my highly aerobatic ships like Giles, Extras, etc. I don't use them if there is much wind, as they can cause the airplane to "balloon" on landing, but when the wind is blowing that hard they are landing really slow anyway.... (I have a landing strip with electric wires on both ends and I have to get the planes down after an almost diving approach.)

    AV8TOR
    If it is not SCARY, it is NO WHERE NEAR powerful enough!!
    All R/C planes have expiration dates---> It's just not printed on them anywhere!


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