Forward sweep wings - RC Groups
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Dec 04, 2017, 10:09 PM
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Discussion

Forward sweep wings


Looking on advice on forward sweep wings, thinking about 10 to 20 degrees, so if anyone has built this type of airplane, please let me know.

Thanks

H.
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Dec 04, 2017, 10:40 PM
Registered User
orcas flier's Avatar
I built a full fuselage, powered, mid-wing sport plane with a wing the same size and outline of the Alula. I added a carbon spar and gave it about 15% thickness airfoil. The first verion is my avatar image. It flies fantastically. Go for it.
Dec 05, 2017, 04:33 AM
An itch?. Scratch build.
eflightray's Avatar
Quote:
Originally Posted by himeros
Looking on advice on forward sweep wings, thinking about 10 to 20 degrees, so if anyone has built this type of airplane, please let me know.

Thanks

H.
Scroll down this page to the 'Similar Threads' list, there are a few threads.

.
Dec 05, 2017, 05:50 AM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
You mean like this ?
Dec 05, 2017, 05:59 AM
Registered User
Extreme Sports's Avatar
...or like this?

My only tips are:
1) Work out the balance before you build - CG will need to be more forward than you are used to, hence the long noses and/or canards
2) No need for wash-out. Some folks recommend using slight wash-in.

Otherwise nothing to worry about
Dec 05, 2017, 08:34 AM
Retired CAD guy
birdofplay's Avatar
Harpy by Chara

Build thread below
https://www.rcgroups.com/forums/show...ht=Harpy%20cat

Full plans available for free plus lots of equipment options.
Cut foam kits available.
Last edited by birdofplay; Dec 05, 2017 at 08:39 AM.
Dec 05, 2017, 01:11 PM
Registered User
Quote:
Originally Posted by gpw
You mean like this ?
Like view #1, not a canard. I understand the "CG" could be forward of the leading edge, depending on how much the sweep is. I probably will start out building right and left wings normal with 6 inch cord narrowing down to 4 inches at tips, then cut the angle on both to get my sweep. As I understand it, I will have to keep the high point at 25 to 30 percent of the cord all the way to the tip, and because of this, the CG will have to be a combination of the two. Just wanting to do something different, making it out of BluCor. Wondering what a good angle would be, and what could be the most angle be and still fly. Thanks for the replies, going to be fun, I have built many different designs out of BluCor and dollar tree foam, no so much out of wood, going to get the paper taped down to my building table and start drawing something out.

H.
Dec 05, 2017, 02:00 PM
Registered User
Extreme Sports's Avatar
Quote:
Originally Posted by himeros
As I understand it, I will have to keep the high point at 25 to 30 percent of the cord all the way to the tip, and because of this, the CG will have to be a combination of the two. Just wanting to do something different, making it out of BluCor. Wondering what a good angle would be, and what could be the most angle be and still fly.
I've probably misunderstood you, but just in case I did not, the location of the 'high point' on the wing has no effect on the location of the neutral point and hence the CG. Wing planform shape and angle of sweep are all that matter. Best to use one of the many CG spreadsheet calculators that float around RCG.

In terms of the angle, just do something that looks pleasing. I don't think there is any magic formula for the sweep angle - if it looks OK, it will probably be OK
Dec 08, 2017, 11:24 AM
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Squall's Avatar
SU 47......

https://www.rcgroups.com/forums/show...rkut-Parkflyer
Dec 09, 2017, 06:51 PM
Ken's CAD Models
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https://www.rcgroups.com/forums/show...nd-Build-Guide



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Dec 09, 2017, 10:08 PM
Registered User

Does sweep make a difference?


The B+W stealth came first. After looking at the planform for some time, the gears started working and the Red forward sweep "Other" resulted.
The plan forms are identical. The spar between the upper and lower fan fold skins was moved, but same power plant. Forward sweep plane required considerable ballast to move CG to the junction of leading edge and nose section. Both fly very nearly the same , high or low speed. This pair is "One way or the Other"
Dec 10, 2017, 03:03 PM
Registered User
Looks like fun, I have about 10 wings and deltas, so I am going to build a standard looking fixed wing airplane, except for the forward sweep wings. I don't see why I can't build one 30 inch wing, then cut the angle for the sweep, and glue the two halves together. Have to use something to reinforce the wings together where the cut is. I am thinking 10 to 15 degrees for my first try, then see how, and if it flies. Thanks for the reply.

H.
Dec 10, 2017, 03:08 PM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
Good Luck to Him !!!
Dec 11, 2017, 08:05 PM
Laughs at un-boxing videos...
basicguy's Avatar

Rs2


Here is one that I built.

30" span. KFm2 wing. Separate elevator. 90 gram leopard motor. 16004s battery.

The CG is just about where the fuselage meets the wing. The motor mount is 1/4" construction plywood mounted on a tongue made from the same material. I originally had a tapered foam box with a hatch. Late summer I designed a printed cover to replace the fuselage.

Nice thing that I found with a slight forward swept wing is it seems to really turn almost perfectly without losing altitude. I have thought about putting in a rudder channel but have not done it yet.

I really like the KFm2 airfoil for wings. The elevator or elevons do not need more than 1/16th or 1/8" reflex.

I have used about the same wing shape but with a straight leading edge and they work about the same.
Here is a flight video.
rs2 3s (2 min 28 sec)


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