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        Discussion My First Scratch build How did I do?

#1 hotdog1 Mar 08, 2011 08:24 PM

My First Scratch build How did I do?
 
Well here is my first Scratchbuild/Non ARF plane it is a 45" Edge 540 Made out of coroplast with a carbon fiber main wing spar. I made this with parts I had lying around so it only cost me $10 for the 2 36x24 sheets of coroplast from my local sign shop.
Here are the specs

AUW is 2lbs 4oz with battery
Cheap HK 9gram servos
Parkzone power 15 (stock motor from the p-47)
Apc 11x8
30amp Eflight ESc
Turnigy 2200mah 3s 30c
Spectrum AR600

What do you guys think ? Also where is a good starting point for the CG ?

http://i344.photobucket.com/albums/p...2/IMG_0558.jpg

#2 Whiskers Mar 08, 2011 11:09 PM

It's very heavy, but that's Coroplast for you. If it was made of foam (this is the foamies group) it would be much lighter. Coroplast is way tougher though.
Have you done anything to stop the fuselage twisting? It will not fly accurately if the tail is twisting under flight loads.
If you have the CG on the front of the aileron servos that will be a safe place for test flying.

#3 hotdog1 Mar 09, 2011 06:48 AM

Quote:

Originally Posted by Whiskers (Post 17628484)
It's very heavy, but that's Coroplast for you. If it was made of foam (this is the foamies group) it would be much lighter. Coroplast is way tougher though.
Have you done anything to stop the fuselage twisting? It will not fly accurately if the tail is twisting under flight loads.
If you have the CG on the front of the aileron servos that will be a safe place for test flying.


yes that is where the cg is now right at the front of the servos. what would you recomend to keep the tail from twisting?

#4 MIJohn Mar 09, 2011 08:14 AM

The suggested CG is a good place to start. I have built the same plane (from foam) Whiskers is right the plane will twist if it is not braced. It will fly the way it is, but it can fly really wierd. The way I did it was to run 2 strips of material from about where the carbon rod is located on your wing running back to the tail to the point where the elevator attaches to the tail. The strips are approximately 1 1/4 inch wide at the tail and almost 2 inches at the wing. You appear to have the rudder and elevator servos mounted on the top horizontal surface so attach the strips on a 45 degree angle between the horizontal and vertical surfaces of the plane (looks like this upside down) \ I use this setup on all my builds to give them a bit more rigidity. I don't know what prop you are planning to use but I have had good luck with an 11" x 8" on that motor. Hope this helps - Good Luck

#5 anatoly Mar 09, 2011 08:47 AM

That looks pretty good to me. 36 oz for a 45" build is only a tad on the heavy side; for comparison my 55" foam Edge 540T is 42 oz with battery and a 2 oz ballast. You probably wouldn't want to do a full fuse version with coroplast, but it should fly fine as long as you have it balanced properly.

Just one piece of advice: that 11x8 prop from the warbird might be a bit fast for this plane. If you're going to try to 3D this plane, consider a lower pitch prop like an APC 11x5.5E or even an APC 11x4.7SF. BTW, when you go down in pitch like that, you should even be able move up to a 12" prop pretty safely.

#6 hotdog1 Mar 09, 2011 01:51 PM

Thanks I think i will use a 12x6 we will see.

MIJohn could you clarify where you are telling me to put the strips ?

do you mean to run them from the main wing down the fusalage to the tail ?

#7 Whiskers Mar 09, 2011 02:52 PM

1 Attachment(s)
This is the sort of bracing strip that will add the much-needed rigidity.
From an engineering viewpoint the Coro 'tubes' should run across the strip, not from end to end.
Run the strip the length of the fuselage, or as much as is needed.

#8 hotdog1 Mar 09, 2011 05:27 PM

Quote:

Originally Posted by Whiskers (Post 17633935)
This is the sort of bracing strip that will add the much-needed rigidity.
From an engineering viewpoint the Coro 'tubes' should run across the strip, not from end to end.
Run the strip the length of the fuselage, or as much as is needed.


oh ! ok that makes sense , what type of material would you recommend using carbon fiber strips, Balsa, ?

#9 Whiskers Mar 09, 2011 06:05 PM

No, just a strip of Coro.
Post #4 has sizes that seem OK. That would make it a piece 2 inches wide at one end and 1 1/4 inches the other, cut 'cross grain' and as long as the fuselage requires.

#10 hotdog1 Mar 09, 2011 06:34 PM

Quote:

Originally Posted by Whiskers (Post 17635678)
No, just a strip of Coro.
Post #4 has sizes that seem OK. That would make it a piece 2 inches wide at one end and 1 1/4 inches the other, cut 'cross grain' and as long as the fuselage requires.

Thats easy enough I went and checked the tail does twist a little I never would have noticed that if you guys did not point it out I an going to put the strips on tonight and weather permiting fly it tommorow I will let you know how it turns out

Thanks for your help

#11 Whiskers Mar 09, 2011 06:45 PM

Cool!
Good luck with the test flying.

#12 hotdog1 Mar 10, 2011 04:46 PM

Well it rained all day so no maiden maybe tommorow will be better weather

What a differance those strips make it is much mor rigged now and only added 1.5oz

here are some pics of it all done

http://i344.photobucket.com/albums/p...2/IMG_0561.jpg

http://i344.photobucket.com/albums/p...2/IMG_0563.jpg


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