RE: Fun with Flat Foam  
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RE: Fun with Flat Foam - 2/6/2008 5:01:57 AM   
calvino


 

Posts: 6632
Joined: 4/17/2007
From: Thousand Oaks, CA, USA
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quote:

ORIGINAL: j.m.

Why didn't you make all 3 wings have ailerons?

eh, sounds like UBER FAST ROLL RATES , not what would seem scale IMO, heck, it is 4 less hinges to fail

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RE: Fun with Flat Foam - 2/7/2008 11:51:57 AM   
cubnpede82


 

Posts: 91
Joined: 9/27/2007
From: Yakima, WA, USA
Status: offline 		Hey all,
new to home built foam board stuff. Just got 3 sheets of elmers papered foam board to give it a try. I like the DR-1 by the way. ! .
I plan to make an SE5 , the e-flite slow flyer inspired me and I got dragged along to the craft store the other day so I decided to find a few things I could use to fly and this was there. I plan to make only a profile fuselage then reinforce with 1/8" bass wood on the tail 2/3 and a stick that will be part of the motor mounting system on the front 2/3, I may make pieces that stick to the sides of the fuse. to have a profile from top/bottom. still not sure there. Any advice on stick mounting a motor would be great. Also is there need to add down and right thrust? and about how much? I'm not sure it's going to work but I'm going to try to get some airfoil into the wing by bending the foam slighty. Is having airfoil really necessary for a light foamy? Any advice on this project or help would be greatly appreciated.

Thanks to all for this wonderful website.

Isaiah
shadymoon1282@yahoo.com

P.S. Here's my first balsa plane, it's still a hangar queen as I'm a fairly NOOB pilot of about 2 yrs.

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RE: Fun with Flat Foam - 2/8/2008 3:23:04 PM   
Pecanpatch



Posts: 860
Joined: 6/26/2006
From: Griffin, GA, USA
Status: online 		Hey,
I think the down and right thrust helps for high powered 3D models but not so much for a trainer type noob plane.

Nice looking tiger moth? I take it that is an arf?

No , you dont have to have an airfoil....... It takes a lot of flying experience just to tell the diffference between a flat wing and one with an airfoil.

< Message edited by Pecanpatch -- 2/8/2008 3:24:20 PM >

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RE: Fun with Flat Foam - 2/8/2008 7:56:59 PM   
j.m.


 

Posts: 2590
Joined: 9/20/2007
From: Raleigh, NC, USA
Status: online 		Um....


No it doesn't. A properly balanced plane with an airfoil will not fly upside down. It will require a bunch of up elevator. Most foam planes however, are what is called a "cg" flyer. This means that the plane gets its lift by having the cg farther back than it needs to be, so the wing has a positive angle of attack no mater what position the plane is in. This will keep it in the air, but by default the airplane will not be stable because the "wing" is very close to stalling.

Anybody will notice the difference an airfoil makes, as it will increase speed (less drag) and run times (more efficient) by requiring a lower throttle setting to maintain level flight. The airplane will also turn much better, and it will most certainly climb faster, as the drag doesn't increase on a proper airfoil quite like it does on a barn door. If you don't believe me, then just look at the drag curves for different aircraft. I guarantee you that parasite drag increases at a much faster rate for a fighter type aircraft with a nearly flat wing, than for a Cessna or Lancair.

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RE: Fun with Flat Foam - 2/11/2008 6:31:34 PM   
Pecanpatch



Posts: 860
Joined: 6/26/2006
From: Griffin, GA, USA
Status: online
J.M.
Your crazy about a properly balanced plane with a airfoil wont fly upside down without a bunch of up elevator.(I think you meant down)
Thats how the IMAC guys will tell you to balance the plane. Till you need no elevator trim either way in upright or inverted flight.

I have the report in my hand were Auburn university did a Wind tunnel test on a flat plate and it is suprisingly effiecent.
The envelopes on these planes are much smaller than what you describe as well.

The airfoil planes do fly better. We have a Hobby Lobby Super Zoom. Great flying airplane. Turns well.But it was $90.

My flipper cost me about $20 with CF rods.

Anyway this is the Flat foam forum for noobs and inexpensive fun planes.

KISS= Keep it simple stupid


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Marko
Traxxas Revo, HPI RS3 4SS, Many many airplanes. Check out my Photo Gallery. Google Geobat for more info.

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RE: Fun with Flat Foam - 2/12/2008 6:37:25 AM   
calvino


 

Posts: 6632
Joined: 4/17/2007
From: Thousand Oaks, CA, USA
Status: offline 		well, I can see with a flat wing, all it gets lift from is the angle of it, sooooo, if you are inverted, it doesn't care

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RE: Fun with Flat Foam - 2/12/2008 9:33:08 PM   
j.m.


 

Posts: 2590
Joined: 9/20/2007
From: Raleigh, NC, USA
Status: online 		i know what you all are thinking, and it does make sense. All that i am saying is that is is much more efficient to fly with an airfoil instead of a flat plate. The IMAC airplanes you are thinking of have a semi or fully symmetrical "airfoil". A fully symmetrical "airfoil" Isn't an airfoil at all. It is simple a teardrop shaped wing. (the most efficient shape under the speed of sound). This is why an airfoil is so much more efficient. One, because a flat bottom wing is exactly half of a teardrop shape, so it is almost as efficient. And two, it doesn't require an aft CG to get it's lift, so the top speed of the craft is automatically increased.

$20 for a foamie is mighty expensive. I built one for about $8, and i am working of converting this right now:
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLFF9&P=7

That's all i'll need besides radio gear, which i can get for a total RTF price of $60. A little sanding work is all that's required. (the wing is already surprisingly stiff).


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RE: Fun with Flat Foam - 2/12/2008 10:19:50 PM   
team3d


 

Posts: 39
Joined: 7/27/2006
From: Wolcott, CT, USA
Status: offline 		Hey guys i am back,

I have a question though and something i think people should try.
I have been having the need for speed latley and been
looking for a cure. But i wanted a hotliner 60" size plane.
I have been planning and thinking how i am going to do this, i wondering
what servos i should use on this type of plane, i am designing something that looks like the Micro flash http://www.espritmodel.com/index.asp?PageAction=VIEWPROD&ProdID=2088
when i am finish i will post pictures.....
I also wanna know if anyone done this before and i would love to see people
give this size plane a try, i wanna see what you guys can come up with.....


chuck

(in reply to j.m.)
       Post #: 3133

RE: Fun with Flat Foam - 2/12/2008 10:43:19 PM   
theradioflyer



Posts: 1299
Joined: 12/11/2004
From: Portage, MI, USA
Status: offline 		Wow, this is a pretty cool thread. I've never check it out before so I've got a lot of reading to do! I love flying depron made planes, the glide slope isn't very good but the teaching vrs $$ is awesome. I learned 3D with foam and then drew up my own planes. My avatar is the first I did and it flew well. The second was a Yak I drew and then painted with acrylic paint out of an Estes Aztec airbrush. To date I designed and flown four flat foam models which I used as a stepping stone to create my own design balsa built-up 3D design which I flew super bowl Sunday and it flew awesome.

God Bless All, I have some reading to do. Here's a video of my 6mm depron Yak 54:

http://www.youtube.com/watch?v=6uXUAzGg2sU

Jay

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< Message edited by theradioflyer -- 2/12/2008 10:49:20 PM >

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RE: Fun with Flat Foam - 2/13/2008 12:44:10 AM   
j.m.


 

Posts: 2590
Joined: 9/20/2007
From: Raleigh, NC, USA
Status: online 		i think you mean the glide ratio, but i get the point.

Actually, because of their extreme light weight, foam airplanes can have some of the all around best glide ratio's of any plane out there. (they are going to be gliders of course)

Foam airplanes are EXTREMELY cheap. I can build them for $1.33 a piece for materials only. (6 sheets of EPS foam for $8)


Instead of using expensive carbon to stiffen things up, you guys should try to use some monokote. It makes a world of difference, and barely adds any weight.

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RE: Fun with Flat Foam - 2/13/2008 4:36:42 AM   
calvino


 

Posts: 6632
Joined: 4/17/2007
From: Thousand Oaks, CA, USA
Status: offline
quote:

ORIGINAL: j.m.

i think you mean the glide ratio, but i get the point.

Actually, because of their extreme light weight, foam airplanes can have some of the all around best glide ratio's of any plane out there. (they are going to be gliders of course)

Foam airplanes are EXTREMELY cheap. I can build them for $1.33 a piece for materials only. (6 sheets of EPS foam for $8)


Instead of using expensive carbon to stiffen things up, you guys should try to use some monokote. It makes a world of difference, and barely adds any weight.

eh, wouldn't the heat to appy it melt the foam????????? , sounds cool though, thought of it, HEY, it prob does about the same as tapin, plus it looks better

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RC18T 6800 Sidewinder Micro 2s lipo, 1980 Goldpan (needs electronics), ST-1, Slow Stick $15 outrunner combo 3s lipo †

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       Post #: 3136

RE: Fun with Flat Foam - 2/13/2008 11:16:23 AM   
j.m.


 

Posts: 2590
Joined: 9/20/2007
From: Raleigh, NC, USA
Status: online 		i have a