[NSRCA-discussion] Wing Sweep Angle?

[J N Hiller]

Matt I would have came back earlier but this morning I opened the CAD files
for my 160 designs to compile some data.
I'm posting this for others that might be interested.

I'm finding wing loading, thickness, taper and sweep important factors. My
first 160 was 11 lb dry and had a wet loading nearly 29 oz / sq ft. felt
heavy in the air, Thickness = 13% Taper = 2.5:1 Sweep = 8 deg.
The second one I built was 10 lb with a loading of 26.5 wet. I liked this
one.
My electric version taper = 2.75:1, 13.3 thick and 7.8 sweep. With 5000
batteries loading was 27.5, which felt heavy. I didn't like it. With 4500
batteries loading is 26, OK but still a little heavy, had to fly too fast.
I'm currently working on a 6 foot E-110 version with an estimated weight
between 9 and 9.5 lb for a loading of about 23, taper of 2.75, thickness of
12% and 6-degree sweep.
All measurements are to the fuselage centerline and the sweep was measured
at the 25% line.

I don't know if I'm in the ballpark with the planned E-110. My gut feeling
is high taper wings can be / should be straighter.
Any and all relevant comments would be appreciated.

As for the roll effect with swept wings, I've only noticed it using heavy
rudder correcting on off line exits from turnarounds.

Jim

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of
rcmaster199 at aol.com
Sent: Sunday, December 08, 2013 8:52 PM
To: nsrca-discussion at lists.nsrca.org
Subject: Re: [NSRCA-discussion] Wing Sweep Angle?

Jim,

The root and tip chords do not have ACs per se, but you know that already.
The AC of a wing panel is located at 25% MAC and everything I've read on the
subject seems in agreement, at least for full scale, so I use that value for
my models. I think that's what Smith is alluding to

The actual angle I think is relative to the fuse CL...So if the wing is
rectangular, sweep is considered zero by convention (I think) (Ron correct
me if there is no convention on this). If sweep is aft, the angle should be
straight forward to measure or calculate. If sweep is fore, same thing
except the sign is reversed.

For the model wings I use (much higher root to tip ratios than every one
else uses), sweep at 25% chord is about 20 degrees to the rear. I haven't
found it excessive or insufficient. It doesn't affect the parameters I use
for wing vertical location on the fuse (given a specific dihedral angle).
This has been tested on 6 original designs so far over the years with
somewhat variable sweep angle (a few degrees, maybe as much as 5 degrees
delta). The dihedral effect delta has been nil.

regads
Matt
-----Original Message-----
From: J N Hiller <jnhiller at earthlink.net>
To: General pattern discussion <nsrca-discussion at lists.nsrca.org>
Sent: Sun, Dec 8, 2013 8:04 pm
Subject: Re: [NSRCA-discussion] Wing Sweep Angle?
Thank you that's exactly what I wanted to know. I've changed it on different
airplanes and wanted to use a 'correct' standard reference when listing
design parameters. I'm finding some sweep is good more isn't, in my opinion.
Jim


-----Original Message-----
From:  nsrca-discussion-bounces at lists.nsrca.org
<mailto:nsrca-discussion-bounces at lists.nsrca.org>
[ mailto:nsrca-discussion-bounces at lists.nsrca.org]On
<mailto:nsrca-discussion-bounces at lists.nsrca.org%5DOn?>  Behalf Of Ryan
Smith
Sent: Sunday, December 08, 2013 2:21 PM
To: 'General pattern discussion'
Subject: Re: [NSRCA-discussion] Wing Sweep Angle?

Hi Jim,

I was always taught to use the aerodynamic center of the root and tip, and
project a line down the span of the wing across these two points. It's
pretty close to 25% generally; it may be a few percent off, but for the
purposes of calculation, it's really close. There are enough variables in
the scheme of things to render that exact enough for our purposes.

I hope this helps.

Best regards,

Ryan

-----Original Message-----
From:  nsrca-discussion-bounces at lists.nsrca.org
<mailto:nsrca-discussion-bounces at lists.nsrca.org>
[ mailto:nsrca-discussion-bounces at lists.nsrca.org
<mailto:nsrca-discussion-bounces at lists.nsrca.org?> ] On Behalf Of J N Hiller
Sent: Sunday, December 08, 2013 4:17 PM
To: NSRCA Mailing List
Subject: [NSRCA-discussion] Wing Sweep Angle?

Question!
How dose one measure wing sweep angle on tapered wing panels? Is it located
as a percentage of cord?
Jim Hiller



_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org <mailto:NSRCA-discussion at lists.nsrca.org>
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org <mailto:NSRCA-discussion at lists.nsrca.org>
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion

_______________________________________________
NSRCA-discussion mailing list
NSRCA-discussion at lists.nsrca.org <mailto:NSRCA-discussion at lists.nsrca.org>
http://lists.nsrca.org/mailman/listinfo/nsrca-discussion
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.nsrca.org/pipermail/nsrca-discussion/attachments/20131209/0a2a7ca1/attachment.html>