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Oct 02, 2012, 09:09 PM
Registered User
AMBeck's Avatar
Here you go. This is an xfoil run at a flight ReNo of 100K, which should be pretty close for a floater style sailplane like the Sagitta. You'll notice that the S3014 has a big advantage between Cl=0.5 and Cl=1.0. This is where thermal sailplanes live. If you build accurately, and use a D box LE, you'll see a performance increase. If you don't build accurately, or if you build open bay, all bets are off. Good luck!
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Oct 03, 2012, 02:00 PM
Kurt Zimmerman ≡LSF 4461≡
kzimmerm's Avatar
Thanks AMBeck... now what would be a good open source CAD program to redraw my ribs?

Kurt
Oct 07, 2012, 01:06 AM
Planes > Time
Thank you all, for the info, I might build a second wing with a different airfoil, to fit the body but maybe not.

Wouldn't you know it, I ask some questions here and start a listing on Ebay, then my primary computer went out. I am trying to get my old one to work now, but wow is it slow.
Oct 07, 2012, 11:42 AM
Jim C Patrick
jcpatrick's Avatar
Quote:
Originally Posted by kzimmerm
Thanks AMBeck... now what would be a good open source CAD program to redraw my ribs?
Not open source, but Draftsight is absolutely free and a great AutocadŽ knockoff.
Oct 10, 2012, 12:42 AM
Registered User
HIR/Cer's Avatar
Quote:
Originally Posted by Larry Jolly
Dave,
Many of Lees's designs could wobble with over zealous inputs to the counter balanced rudder. I was trained on the Hobie Hawk and never noticed the wobble or shimmy, I just flew the airplane. The Sagitta is a little short in tail moment as Lees's designs were designed to go in a 42" box. But if it were me, I wouldn't change a thing except...
Get rid of the pine wing joiner box and instead use a 1/16" plywood front web joining the spars at the wing root. Make sure you do a good job of getting a smooth radius on the cable elevator pushrod, or replace it with a bellcrank drive system. Other wise leave the Sagitta stock and enjoy it. LJ
A friend built the Sagitta 900, stock, when the kits were first available, had no problems with the build, and was very satisfied with it flying in moderate to light lift. One of the wing joiner boxes did eventually fail, however, and he never did rebuild it.

Looking over an Airtronics Sagitta 900 kit I had purchased a couple of years ago from a fellow RCG member, the quality of the kit is excellent with clean machine cut parts, well selected balsa, sturdy air ply fuselage sides, and easy to follow instructions and plans.

Back then, built the Sagitta 600 myself following my friend's satisfaction with his 900 and it was also a great kit. Followed the instructions to add ailerons (my first 4 channel) and it was also a great flyer, more manuverable but needing more lift than his 900 as is to be expected.

Am hoping that Aerosphere will one day have the Sagitta kits available.
Oct 10, 2012, 06:27 AM
Registered User
Aerosphere WHAT A JOKE, has to be the BIGGEST blunder in model aviation history. Takes over a great product line and holds it hostage for 5+ years with not even a peep from its owner other than "were closed for renovations and will open after the New Year", Wonder what century he was talking about. I wish there was a "you don't use it you lose it" rule. That way crap like this couldn'happen


Quote:
Originally Posted by HIR/Cer
A friend built the Sagitta 900, stock, when the kits were first available, had no problems with the build, and was very satisfied with it flying in moderate to light lift. One of the wing joiner boxes did eventually fail, however, and he never did rebuild it.

Looking over an Airtronics Sagitta 900 kit I had purchased a couple of years ago from a fellow RCG member, the quality of the kit is excellent with clean machine cut parts, well selected balsa, sturdy air ply fuselage sides, and easy to follow instructions and plans.

Back then, built the Sagitta 600 myself following my friend's satisfaction with his 900 and it was also a great kit. Followed the instructions to add ailerons (my first 4 channel) and it was also a great flyer, more manuverable but needing more lift than his 900 as is to be expected.

Am hoping that Aerosphere will one day have the Sagitta kits available.
Last edited by rouge flyr; Oct 12, 2012 at 07:05 AM.
Oct 13, 2012, 01:30 PM
can ya do that??...
electroboy's Avatar
Im curious what folks are using for spars nowadays as I can't find any spruce.
I was putting together a parts supply to build one and found no spruce.
Confounded, I gave up.
I have considered using basswood/ CF laminated on the bottom surface of the bottom spar as I reckon upward flex (tension) is probably the primary structural concern.
I also considered 1/8x3/8 CF pultrusion spars throughout.

still considering...doing nothing.

What methods have recent builder's used?
Oct 13, 2012, 07:20 PM
Registered User
Compression is probably somewhat more of.a problem, actually, because you can get buckling.

1/8 x 3/8 carbon would be total overkill. Go to chalesriverrc and look up drawings for Allegro Lite and Bubble Dancer for construction that can take brutal winch.launches. Or you can cap wood spar caps with....014" carbon on a two meter if you can tap.
Oct 13, 2012, 07:23 PM
Registered User
If you search for west coast Pietenpol you will fimd a guide to wood.for.aircrsft building. Many kinds are good for aircraft, including Douglas For.
Last edited by lincoln; Oct 14, 2012 at 12:43 AM. Reason: it's Pietenpol, not Pietenpole
Oct 13, 2012, 07:24 PM
I don't want to "Switch Now"
pmackenzie's Avatar
FWIW, there are some details for building a winch proof woody spar system over on Ray Hayes SkyBench site:

http://www.skybench.com/index.html?h....com/home.html

Pat MacKenzie
Oct 14, 2012, 01:08 AM
Registered User
More stuff on spars:
http://charlesriverrc.org/articles/d...mproofwing.htm
This guy talks about some tropical wood that's stronger. Even sugar maple is a lot stronger, though also heavier. However, compared to spruce you could probaby use half as much and still have a stronger spar that might even weigh less. This is because, since it's stronger, you can use a thinner cap and have more of it near the top (or the bottom) of the spar. The closer the material is to the top or bottom, the more it contributes to the strength and stiffness.

https://www.rcgroups.com/forums/show...mentid=3981474
This one's about adding carbon to spars. I tend to think that the amount recommended may be overkill unless you wrap the spar with carbon and perhaps leave out the wood caps and use end grain shear webs that go from one carbon cap to the other. But certainly adding the carbon will make the wing stronger if you do it well. Whatever adhesive you use, test some samples to make sure it won't let the carbon peel off easily.
Oct 14, 2012, 02:17 AM
Registered User
Ok, I got curious and did some web surfing. Maybe you'd need 2/3 as much for the maple. But black locust is supposed to be 80 percent stronger than sitka spruce, more or less. You'd want to inspect the grain on individual pieces of wood, though.

You can also make the spars wider near the center, or taper them, since there's a whole lot more stress in the center than there is further out.
Oct 14, 2012, 06:39 AM
Registered User
whacker's Avatar

I built the Elio


I built the Elio with s3021, wing profile...

Not a problem with 1/8 x 3/8 basswood, top and bottom, over 100 tows with a hi start stretched to 18lbs
No pine block for wing tube carrier.
reinforced front and back with 1/16 ply...

Of course every ones experience is different..

google 'elio sailplane', there's lots of pictures..



whacker
Oct 14, 2012, 02:22 PM
Registered User
1/8 X 3/8 spars in a normal 100 inch glider, assembled with good craftsmanship, is just fine for a hi start or a winch tapped with a modicum of skill. With a heavy foot, it's another story.

I didn't find all that many pictures of the assembled glider, but I liked what I saw.
Oct 17, 2012, 09:27 PM
Balsa addiction since age 3
ScottSails's Avatar
Quote:
Originally Posted by lincoln
1/8 X 3/8 spars in a normal 100 inch glider, assembled with good craftsmanship, is just fine for a hi start or a winch tapped with a modicum of skill. With a heavy foot, it's another story.

I didn't find all that many pictures of the assembled glider, but I liked what I saw.
No picture of finished glider? Hint - look left....


And some of us built standoff "Sagitta's" with 115" wing and oh say MH32 airfoils...
(and winch in the nose)...
Last edited by ScottSails; Oct 17, 2012 at 09:39 PM.


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