HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 28, 2009, 09:38 PM
Registered User
Joined Dec 2009
3 Posts
Idea
SFG's on Eflite Extra

Hey fella's,

My first post here, just been reading alot, seems like an awesome place! I've been flying since '06, but recently had to get rid of my inventory when I joined the service. A couple months back, after I got all settled in, I picked up an E-Flite Extra, my first electric. Small electrics seemed to be a perfect solution to my new space requirements.

I've been really happy with my Extra, but it seems, as other have noted it has a lot of wing rock in a harrier. And coming from 35 and 40% airframes it especially seems excessive. I've been reading, and at the same time thinking (which usually means trouble) what if I put SFG's on it? I thought maybe first I'd go with foam to try out the design. Symetrical top and bottom, airfoiled leading edges, and two small bass wood blocks, with two small nylon bolts per wingtip would be fine for strength. The problem I've run into seems to be a design, should I just look at existing SFG's and mock one of them? Or is there a preferred style?

I would eventually make them out of balsa, air foiled, covered to match the plane and carved so that the ailerons have room, however, I think foam will be cheaper and easier to work with in the beginning.

Any ideas?
CNEEL89 is offline Find More Posts by CNEEL89
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 28, 2009, 10:19 PM
Just "hanging" Around
3D-Dabbler's Avatar
Richmond, VA
Joined Oct 2009
1,589 Posts
I would just copy one of the many styles of SFGs used on production RC planes on the market.

Foam might not be strong enough. You might need a strip or 2 of 1/8" plywood or something similar to keep them from bending in flight. Or wood is pretty cheap you could just trace your pattern on a solid piece of balsa, beach or plywood and slap it on the plane. Start with your biggest pattern and then as you experiment you can continually remove wood instead of needing a new piece every time.

I plan to put some SFGs on a plane that I own as well. I am going to base the design off the pattern from another plane that I own that came with SFGs. I just traced the pattern on thin plywood. I figured that would be stiff enough. If it works then I planned on covering them and airfoiling them like you mentioned.
3D-Dabbler is offline Find More Posts by 3D-Dabbler
Reply With Quote
Old Dec 29, 2009, 12:16 AM
TEAM EXTREME FLIGHT
Doc Austin's Avatar
USA, FL, Largo
Joined Dec 2005
16,446 Posts
Quote:
Originally Posted by CNEEL89 View Post
Any ideas?
Eyeball it. They don't have to be that scientific to work. I eyeballed the ones on my Yak and made a brand new plane out of it. I sized those down for the stab and it made an even bigger difference.

You're going to a lot of work to airfoil them and all that. Just slap some sheet plastic on the tips, guess at the shape (though copying the Extra SR SFGs would be a good idea because those are great) and throw it in the air.

Of course, you want the shape to be identical top and bottom, but I don't think it's critical. That is, I mean unless you come up with something really bizarre.

Of course, airframes have come a long way recently. Planes like the Slick have absolutely zero wing rock. You can minimize the wing rock on your current plane, or get a plane that has none to begin with.

I'm guessing you're enjoying the challenge, so play around with different shapes untl you hit what you like. Bigger seems to work better, but then it gets to the point it looks so goofey you can't stand to look at it.
Doc Austin is online now Find More Posts by Doc Austin
Reply With Quote
Old Dec 29, 2009, 12:28 AM
Registered User
Joined Dec 2009
3 Posts
Yea I'm just enjoying the challenge. I have several other ideas for this aircraft as well .

I think I'll look around at some sfg's and try to figure out the traits each shape has, and maybe try to make a mutant of them, or just do my own thing. I also thought about the SFG's on the stab, but I wanted to try this first, and I thought I may try to build counter balances and maybe later design an SFG around them.
CNEEL89 is offline Find More Posts by CNEEL89
Reply With Quote
Old Dec 29, 2009, 06:32 AM
TEAM EXTREME FLIGHT
Doc Austin's Avatar
USA, FL, Largo
Joined Dec 2005
16,446 Posts
Quote:
Originally Posted by CNEEL89 View Post
I also thought about the SFG's on the stab, but I wanted to try this first..........
I tried them simply because I thought the plane would look better balanced, and while it did, it also helped the Yak's flying considerably. I mean, there isn't much you can do to make a Yak look any weirder than it already does.

These are 3DHS Extra SR SFGs that were too long. I simply lined up the rear with the TE of the ailerons, and lobbed off whatever stuck off the front. Then I resized them on my computer to match the chord of the stab. OK, some people think they look weird, but I liked them.



What I like about these SFGs is that they are big enough to work, but they aren't so big that the plane looks cartoonish. Well, ok, maybe the Yak looks cartoonish, but on the extra they look just right.



Basically I think SFGs, in many cases, are a bandaid to block wing rock on existing designs. They also have you a lot of extra lift and stasbility in KE. I tried a set on my first Slick and since it didn't have any wing rock to begin with, there wasn't much difference except KE was a bit better, but then again, my KE needs all the help it can get.

The newer planes like the Slick and 3DHS Edge 540 have no rock at all. Since you are used to flying 43% jobs, I think the Slick will fly most like what you are accustomed to. Depending on the gear you have, most of your equipment in the Extra will probably fit in a 42" Slick, which is a teriffic little plane.
Doc Austin is online now Find More Posts by Doc Austin
Last edited by Doc Austin; Dec 29, 2009 at 06:47 AM.
Reply With Quote
Old Dec 29, 2009, 09:52 AM
Aerodynamically challenged
3Deranged's Avatar
3D World, Florida
Joined May 2005
3,173 Posts
Here's an SFG shape that works great on a larger Extra. 6mm foam sheeted with 1/32" balsa and a carbon tube for stiffness. 6mm foam with a couple of small dia. carbon rods CA'd on both sides should do the trick. Suggested this setup for one of my customers with the same airframe. He's tried it and it improved overall flight characteristics according to him. He's trashed a couple of sets in the last few months but they're easy to make so he just makes a couple of sets and keeps one as a spare. Just need to make a rib shaped standoff for a spacer and 2 or 3 wood screws and you're in business. And a couple of lite ply discs glued on to outer side and/or square balsa stock glued in for strength are a good thing too.
3Deranged is offline Find More Posts by 3Deranged
Last edited by 3Deranged; Dec 29, 2009 at 12:01 PM.
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale 3DH 47" Extra-sr (wheelpants & SFG) relax1 Aircraft - Electric - Airplanes (FS/W) 4 Dec 07, 2008 10:46 PM
For Sale Make Offer On Eflite extra 260 & 40amp esc mike240se Aircraft - Electric - Airplanes (FS/W) 1 May 22, 2008 05:40 AM
Sold Eflite CP / Extra's **SOLD** zdsh13 Aircraft - Electric - Helis (FS/W) 1 Jan 19, 2008 11:13 PM
Sold Eflite Extra 260 + Scorpion s-3008 32 Ronald Dobbs Aircraft - Electric - Airplanes (FS/W) 5 Dec 03, 2007 10:19 AM
Discussion Side Force Generators (SFG's) on Extra 330 Suitcase from HL nebg9 Electric Plane Talk 1 Jan 30, 2007 12:46 PM