scratch hand launch/discus - RC Groups
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Mar 10, 2003, 12:58 AM
Registered User

scratch hand launch/discus

Wanted to try this hand launch bit so scratch built this bird this weekend. AUW with radio gear installed ready to be pitched is 3.7 oz.
wing span 39 inches
airfoil SA7036
wing: balsa build up with beam main spar/ D tubular reinforced with carbon tow. Solite covering.
fuselage is smallest wrapped tapered rod.
Radio: Hitec Feather with hs55 in wing, and cs 10 for elevator stuck way out on the nose. Reciever battery is Kokam 145 lipoly.
Balance was not too bad. Yes, I did mount everything way out front, but it seems okay. Adding weight, ie ballast to front to balance just seems like a sin to any object trying to fly.

Flights: Honestly, hard to compare since this is a first, and I have only seen one other HLG. I think it is okay, but my initial throws only get it maybe 50 feet. I find it difficult to gage height. Ended up discus throwing it. No problems with throwing it hard except the wing would slip a little because of too few rubber bands. Tried at slope above my house and it flies great. Ailerons are very responsive. Need to fine tune. My aileron push rods are too flimsy (flutter on one of my heavy throws).

If I were to do it again, I would change to a thinner foil to decrease my drag. I think the wing is actually way over built and could easily tolerate a thinner foil. I also now need to figure out how to enclose the front end radio gear. I like having easy access to the gear, and would like some easy "shell" attachment to enclose the gear. Any ideas? Definitely would stick with the lipoly cell. Oh yeah, the aileron set up is not that clean on the bottom surface and I believe induces quite a bit of drag. Any building tips to make clean aileron hinge line? I would consider v-tail and dihedral next time. Small carbon wrapped tubes are absolutely amazing. I would use that component again in a heart beat. The composites are truly amazing materials.
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Mar 10, 2003, 08:11 PM
Motor Maniac
I don't know if you can get much higher launches at this weight. There's just not a lot of inertia there. Maybe with a thinner wing you could get more launch, or maybe better launch technique. I may have a Gadget DLG in the mail here soon, so we can compare that with your scratch-built as far as launch height is concerned.

Maybe we should try bungee launches? I need to figure out how to put a hook on my Gambler. I have an idea for it, just need to work out the details. Should be easy on your HLG.
Last edited by 10Thumbs; Mar 10, 2003 at 08:16 PM.
Mar 11, 2003, 03:23 AM
Registered User
put a tow hook on your hlg and lets do some towing behind some planes this weekend. I have a decent tow airplane that flies slow and should have enough power. We need to get into some thermal territory.
Mar 11, 2003, 11:08 AM
Motor Maniac
I'm out of town this weekend, so it will have to wait. Maybe you can get Dave to pilot for you.
Mar 12, 2003, 11:03 AM
Gambler-AG DLG Designer
Allan Wright's Avatar
You should be able to scratch up a slab-sided balsa pod out of 1/16" sheet to go around your equipment. The added weight will be more than compensated by the reduced drag. Carve up a nice rounded nose out of some balsa block and you'll be in business.


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