What size engine? & will it fly.
08-20-2003, 08:33 PM
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What size engine? & will it fly.
This is a scratch built and I was wondering what size engine I should put on it I was thinking about a Gms .25 2 stroke. This is my first scratch built airplane so tell me what you think.
08-20-2003, 11:07 PM
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What size engine? & will it fly.
I don't have a balsa plane that small, but I have flown coroplast planes a bit bigger and heavier with a .28. I feel the .25 may be too much engine for your design. Try a .15?
08-20-2003, 11:51 PM
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What size engine? & will it fly.
I agree, i would sudget though a .20 2 stroke or better a 30 4 stroke. I think the 4 stroke would be better for it, but if the budget gets in the way a .15-.20 would probibly be good. but you can always use a .25 and richen it up a ton so you don't have full power while making it easier to be seen by all the smoke. (Someone in my club did that on a much larger scale.)
08-21-2003, 12:25 AM
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What size engine? & will it fly.
what do you think a good weight is. right now it weights 20 ounces with out the engine and landing gear. Also someone told me 1/3 of the cord and then 1/2 an inch back is a good C.G.
08-25-2003, 09:35 PM
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What size engine? & will it fly.
I think that CG is too far back. Usually it's between 25% and 33% of the chord. Better to start with 25%, and then gradually move it back.
I agree that a .25 is too much, as your all-up weight will be less than 3 lbs. I am scratch building a .25 inch Spitfire, 45 " wing, and I hope that the weight will be 3lbs, or a little more. It should be pretty fast.
Good luck with it.
I agree that a .25 is too much, as your all-up weight will be less than 3 lbs. I am scratch building a .25 inch Spitfire, 45 " wing, and I hope that the weight will be 3lbs, or a little more. It should be pretty fast.
Good luck with it.
08-26-2003, 06:20 AM
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What size engine? & will it fly.
That's definetley not enough model for a 25. The wing is lightly built so I would worry about the high speeds the 25 could fly it at causing flutter. A 10 to 15 would be a much better match. Possibly even a Norvel 074.
The other reason I think a smaller engine is better is the wing area. There's only 292 sq inches and that is not much bigger than many 1/2A models. To keep the landing speeds down to a reasonable speed and help prevent nasty stalls I would not want to see the weight go more than about 32 oz and more like 27 would be better. You say the airframe as shown is 20 oz. I see a servo in the wing so I gather that means the only things missing are the landing gear, covering and engine? No other hardware or gear to add? If so that's not bad but you're gonna be close. to that 30 oz figure. Even at 30 oz I see this model having a "hot" landing speed.
If you had built it up to 40inch span by 9 chord for the same weight I'd say you could get away with a 25, assuming the wing was built a little more ruggedly. It would still be a hot flyer but the wing area would let it handle the engine weight for landings.
But from what I see you've done a nice job. The structure is light and looks clean. The tail details are crisp and light. I don't know what you used in the fuselage or how heavy your radio gear is but I like what I see. Perhaps a lighter battery pack? What's in it now? By the looks of that servo you could shave a couple of oz by getting some mini servos too. On these smaller models each oz counts for a lot too.
The other reason I think a smaller engine is better is the wing area. There's only 292 sq inches and that is not much bigger than many 1/2A models. To keep the landing speeds down to a reasonable speed and help prevent nasty stalls I would not want to see the weight go more than about 32 oz and more like 27 would be better. You say the airframe as shown is 20 oz. I see a servo in the wing so I gather that means the only things missing are the landing gear, covering and engine? No other hardware or gear to add? If so that's not bad but you're gonna be close. to that 30 oz figure. Even at 30 oz I see this model having a "hot" landing speed.
If you had built it up to 40inch span by 9 chord for the same weight I'd say you could get away with a 25, assuming the wing was built a little more ruggedly. It would still be a hot flyer but the wing area would let it handle the engine weight for landings.
But from what I see you've done a nice job. The structure is light and looks clean. The tail details are crisp and light. I don't know what you used in the fuselage or how heavy your radio gear is but I like what I see. Perhaps a lighter battery pack? What's in it now? By the looks of that servo you could shave a couple of oz by getting some mini servos too. On these smaller models each oz counts for a lot too.
08-27-2003, 12:25 AM
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What size engine? & will it fly.
The airplane has everything in it including all the servos(4 plus battery and receiver) all i need to buy is the the engine and landing gear (vented 100 landing gear 0.49-.25 plus 1 3/4 inch tires) With a.15 what size tank do you think i will need?
