Homebrew Mini DLG Build - RC Groups
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Oct 27, 2004, 12:51 AM
Hutch's Avatar
Build Log

Homebrew Mini DLG Build

Well folks, I have been watching this place for about three years now and am finally becoming a participant. I have been dying for something small and portable that I could have fun with. There are many great planes out there but in my opinion nothing beats the satisfaction of heaving your own bird into the great wide open. That being said, if it weren't for the wealth of information and contributions of others in these forums I may not have given this a whirl. My yet unnamed bird's rough specifications are as follows:

Wing Span: 36"
Wing Area: 171 Sq"
Root Chord: 5.5"
Tip Chord 4"
Airfoil: AG-03

More to come assuming I can get the photo posting figured out....
Last edited by Hutch; Dec 21, 2005 at 08:17 PM.
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Oct 27, 2004, 02:27 AM
Hutch's Avatar
For the vertical and horizontal stabilizer I used 1/32 balsa with carbon tow reinforcement, and light fiberglass. The drawings show two vertical tails. I drew the tall one first, but after reading about Denny's reasons for the new XP-4 tail surfaces, I went with the lower aspect ratio version. I used the poor mans "bagging" method to apply the fiberglass after sanding the balsa to shape. This was my first time using this technique, and the results weren't too bad. Pretty neat idea for those of us who haven't made that coveted next step towards total vacuum bagged sailplane nirvana.

Details on the technique are here.... http://www.sjsf.org/waxpaper/waxpaper.htm
Oct 27, 2004, 03:59 AM
Registered User
nice work.

if yor tail servos are in the back of the fuse, you may want to consider a longer nose for balace, but it looks like you have 4 x 270mah batteries up front. it will be close.

i built a 48" span and have 2 servos, rx and 4x110mah in the nose, before the wing and it just balances.
Oct 27, 2004, 11:14 AM
Hutch's Avatar
I am a little worried about having to add weight to the nose. The components that I drew the plane around are as follows:

Battery : SR Batteries SR-190 flight pack (1.3 Oz)
Servos : 4 Ea. Cirrus CS-4.4 (Total .76 Oz)
Receiver : Berg 5*DSPII W/ Case Removed (.34 Oz)

That doesn't leave me much room for error in creating a light airframe. I am trying to keep the wing loading under 6oz/Sq'.
Oct 27, 2004, 08:01 PM
Registered User
heres a pic of the nose of a 48" dlg.
1.96 sq. ft. wing area
7.4 oz auw
rudder elevator only
nose 7.25" from leading edge
Last edited by sloppytypist; Oct 27, 2004 at 08:04 PM.
Oct 28, 2004, 12:08 AM
Hutch's Avatar
With the tail parts complete, I moved to the wing. Les Horvath cut some great cores for me. The wing is sheeted with light 1/32" balsa. I reinforced this with a 3/4" wide strip of carbon fiber fabric along the top and bottom. Then I mixed up some epoxy and sandwiched everything up. The carbon may have been overkill, but my thinking was that with a discus launch I would want some sort of pseudo spar to tie the wing together. I wasn't too sure if the balsa alone would have been strong enough.
Oct 28, 2004, 12:14 AM
Hutch's Avatar
The next morning I pulled the weights off, and pulled the cores out of the beds. A little sanding and shaping and I'll have a shiny new set of wings!
Oct 28, 2004, 10:12 PM
Hutch's Avatar
With the leading edges attached, the tips cut and tip blocks installed it was time for some good old fashioned sanding. Once that was complete I glued a carbon fiber reinforcement for the launch peg to the top and bottom of the left tip. This also served to tie the joint between the tip block and the foam core together. Once that was dry and lightly sanded I trimmed some ultra light fiberglass to the shape of the wing. Finally I wetted out the fiberglass with some epoxy and blotted the excess with reckless abandon. Time to do something else while the wing cures.
Oct 28, 2004, 10:16 PM
Hutch's Avatar
Rudder and elevator cut away from their respective tail surfaces.
Oct 29, 2004, 02:47 AM
cranium accessories
dustn's Avatar
wow hutch! looks nice!

i'm looking forward to a flight report!
Oct 29, 2004, 03:49 AM
Registered User
with cf spars, wood and glass - won't the wings be a little heavy ?
Oct 29, 2004, 05:10 AM
fly-crash and resurect
yorbenator's Avatar
how could i get in touch with the guy that cuts your cores??
and how are you gonna do the fuse???
Last edited by yorbenator; Oct 29, 2004 at 05:16 AM.
Oct 29, 2004, 11:25 AM
Hutch's Avatar
Dustin: Thank you! I'm looking forward to seeing if it flies too.

Mr Wood.: I am definitely going to be out of the 3-4 oz/sq' range unfortunately, but that is one of the reasons I ordered two sets of cores. This was definitely a "lets see how everything ends up if I do it this way" run. Unfortunately I am used to building slope planes so I still have build it too strong and build it too heavy stuck in my head. I am trying very hard to suppress that instinct in this build. I am borrowing a scale this weekend so I will be able to get an accurate idea of the weights of my components.

Yorbenator: He has a website http://www.compufoamcore.com/ His e-mail is on the website. Just let him know what you are looking for, and he'll give you a quote. Before you know it you are opening a box with some very well done cores just begging to be turned into a sailplane.
Oct 29, 2004, 02:46 PM
Registered User
windsox's Avatar
It is not a loss. It sounds like your first design was a bit overbuilt. but assuming it fly's well it will still make a sweet light lift sloper!
Oct 29, 2004, 03:47 PM
Good thing balsa floats!
Rain City Flyer's Avatar

Looking Good

Hutch - Looks like a scratch-built (and improved) version of the Art Hobby Colibri.

As mentioned above, watch your fuselage length as it appears to be very short. A longer nose and a lighter battery will go a long ways towards a lighter AUW.

Keep those photos coming!

Scratchbuilding Rules!

Chris in Seattle

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