How long from maiden flight on first plane to sucess with EDF jet? - Page 3 - RC Groups
 Apr 22, 2007, 05:33 AM Gliding like a rock! Hmm... OK, now I get wing loading. Thanks for explaining that. I will indeed need to calculate that out just to be safe. If I need more wing surface area, can I just glue on a few extra inches to the ends of the wings making them longer? The COG should be easy enough to manipulate just by fooling with the battery. It's by far the heaviest thing in the plane. Everything but the motor is located right under the wing & has plenty of room to be shifted some front or back to get things right. You're right about the wing not having any dihedrayl. I was hoping it would still have some friendly manners because it's a high-wing with a low COG. Am I asking for trouble here?
 Apr 22, 2007, 06:09 AM Registered User If you want to fly EDFs... try getting a fast slope soarer first, they have about the same speed range, and don't have the 8-odd minute flight times. Something like a Reaper, or some other fast 60" sloper. I tend to run out of *transmitter* batteries in a single flight with slopers...
 Apr 22, 2007, 07:00 AM It's a Great Day to Fly I usually calculate wing loading in ounces per square foot of wing area. For example if the wing is 30" x 6" = 180sqin. Divide by 12"x12" = 144sqin to get 180/144=1.25sqft. if the plane weighs 20 ounces you have 20/1.25= 16 ounces per sqft. I think this is heavy. I know 11 ounces per sqft is a floater in a 40" span and because of the way aerodynamics work as you get smaller (the air stays the same density) it needs to have a lighter wing loading the smaller it is. At 16 ounces the wing loading for our hypothetical plane becomes 12.8 which is certainly better but probably not a floater. Len
Apr 22, 2007, 09:05 AM
I'm off my medication...
Quote:
 Originally Posted by Oreo The COG should be easy enough to manipulate just by fooling with the battery. It's by far the heaviest thing in the plane. Everything but the motor is located right under the wing & has plenty of room to be shifted some front or back to get things right.
Have a play and see if you can get her balanced with current battery/engine etc. Sometimes you can't move the battery forward far enough because it would obstruct the prop

Quote:
 Originally Posted by Oreo You're right about the wing not having any dihedrayl. I was hoping it would still have some friendly manners because it's a high-wing with a low COG. Am I asking for trouble here?
She should be reasonably stable. Certainly an overwing design will help. But she will be handful until you have her trimmed. With no dihedrayl she will go exactly where her control surfaces guide her which might make the maiden... exciting. If you put in the sim time I'm not sure you will need the self correction so much.

Did the previous wing have a reinforcing rod? Have you put one in your new wing?
 Apr 22, 2007, 07:18 PM R.I.P. Dimebag are EDFs really all that much faster than a conventional prop? had a peice of crap EDF a while ago. I was more of a toy, but i took it about and still have the moter/fan. could i ghetto strap that to the plane i have now and it be worth while? I reallize i would need to put a shrinking tube on the end of it for more thrust
 Apr 22, 2007, 07:34 PM Registered User There are EDFs and EDFs... something like a GWS A10 is pretty slow, just like the real thing. But it is possible to get EDFs up around the 150kph mark without spending a fortune, and given they're pretty small, that's plenty fast... something like 5 or 6 times as fast as what you're building now, which will do around 30kph. But then, I have a prop plane that does 150kph, and a slope glider that will do well over 200... it's not that fast, especially if you go talk to the dynamic soaring folks. Their world records... for gliders remember... are up near 490kph, and low 300s are pretty routine these days! The real challenge with EDFs is that, other than A10s and airliners, they're small and heavy, and that means they land very fast because of the wingloading.
 Apr 22, 2007, 08:36 PM Gliding like a rock! The previous wing did have reinforcing rods going from about half way out the wing down to the fuselage. The old wing NEEDED it. The new wing, not as much. Although I'm thinking of putting it on just in case. Don't want to break a wing mid flight. She's almost completely built. I just gotta put hinges on the flaperons & that's it. Then adjust COG & do a preflight check.