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Old Nov 11, 2006, 07:23 AM
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Show us your scratchbuild foam (Motor) Glider !!!

Guys,
I believe that (motor) glider models are way too underrepresented in the scratchbuild-foamy section!

Do we really want to accept that those balsa/fiberglass builders look down at us and say that our foamies fly just because of a high thrust to weight ratio???!!!

So here you can SHOW THE WORLD YOUR MODEL and prove what a determined foam scratch builder can do with a sheet of blucre/depron and an x-acto knife!!!
I'd be surprised if we can not soar and thermal the out of those 300$ ARF models.
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Old Nov 11, 2006, 09:11 AM
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ok, I'll make the start...

Made a full profile wing (85cm span) a while ago to experiment a bit with wing building techniques.
My ultimate goal is to make a little scratch built foam motor glider with the best possible glide performance. So I've cut out a few pieces of foam to form a simple streamlined fuse and some tailfeathers...
So... here is "MOSE-01" (MOtorSEgler - motor glider).
RET control, 165g AUW. A bit heavy I could have done it probably around 150g if i took more care.
Did not maiden it yet cause the weather sucks...
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Old Nov 11, 2006, 11:32 AM
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Nice and Well done!

Nach wieviel Weissbier ist das entstanden?

Gruss aus Kempten,
Ernst
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Old Nov 11, 2006, 01:20 PM
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Nice lookin' bird there, Chara. With that huge rudder coupled with the polyhedral, it's probably gonna be pretty touchy and easy to over-control. Might need to minimize rudder throw and/or reduce rudder area.

Bill(oc88)
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Old Nov 11, 2006, 01:48 PM
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Very nice looking bird, Chara. What motor and prop are
you using. I think you're right. A motor glider can be a lot
of fun. I'll be watching to read of your adventures with
your plane. Meanwhile, I'll see what I can start here.
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Old Nov 11, 2006, 01:50 PM
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Ernst, thanks! 3 Weissbier, dazu 3 Weisswurst und Brezn ... Gruß zurück

Bill, thanks for the tips! I'll bring a cutter on the maiden flight so I can adjust the fin sizes. Dihedral was a bit small initially so I readjusted it...hmm, maybe I've overdone it. Hope the weather will be better tomorror!
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Old Nov 11, 2006, 02:09 PM
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WWII thanks!
the motor is a little BL inrunner (12mm diam. type) with 3500kv. Pulls around 4A on 3 cells. The prop is a 3x3 cam slim from Graupner.


Come on guys! whoever has built something that glides and soars nicely and is out of foam, please POST IT HERE!
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Old Nov 11, 2006, 03:25 PM
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This wing didn't take long to build, I think I spent longer researching the aerofoil than I spend building it.

I hot wired a couple of EPS wings, cut and bevelled the polyhedral and used carbon rods top and bottom in the centre section for strength and then covered in packing tape.

I didn't think it was going to measure up against a balsa glider wing, but when I weighed a similar sized wing from a similar sized glider it was exactly the same!
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Old Nov 11, 2006, 03:31 PM
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Chara looks great! This is definatly something I have benn working on my self. I have taken some planes for a Global Easy Answer and started building it from Pro board. Center wing is sorta done and fuse is mostly done. Looking to use an Essky 400xt for the power plant on it. Will post pics later on today.
I am surprised more people are not building gliders. I learned to fly on one amd love how they just float and seem to fly forever, power up to elevation and cut the juice and glide around.
Harry
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Old Nov 12, 2006, 09:40 AM
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thats great Robin! how did it fly?
Hot wiring gives you lots of options, what kind of airfoil did you use finally?
I've made some research as well for low Re profiles, but in the end I had to make a compromise between simplicity of build, structural strength and aerodynamic efficiency. It is a kind of Clark Y what came out finally.
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Old Nov 12, 2006, 09:55 AM
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WB I'm looking forward to see your pics! You're right! I wonder myself why I haven't hardly found a glider thead in this forum. Hope this is going to change!!!

Gliders have their own appeal: the high requirements/challenges for the designer and also the joy you feel whet they just glide silently and seem to stay up forever without having to change batteries every other minute.
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Old Nov 12, 2006, 11:18 AM
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I started this mod on my Alula last night. Adding that much weight way out there on a sub 4 oz plane doesnt seem too bright though. I'm going to shorthen it up alot to get the battery back on the CG.

My F5D plyon racer was meant to be a sloper. The airfoil was not very efficient "semi-symetrical", so it was religated to a parkflyer. My feathercut will fix the efficiency problem on my next try.

Boz
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Old Nov 12, 2006, 03:35 PM
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> thats great Robin! how did it fly?

For the first flight I used the stock slow stick motor and it was great - 15 minutes of floating around the field while lying on my back in the hot sun. Then I noticed some dihedral that wasn't there before, then there was a LOT of dihedral, then it came down like a lawn dart...

I had originally used only plastic box strapping as a top spar (the plastic strip that comes wrapped around boxes of printer paper) with strapping tape as the bottom spar. I think the sun softened everything until the spar could buckle.

As it was a foamy I just bent it straight and melted a slot for CF rod. After that it was much stronger.

I'm not much of a glider pilot, and it's built for a competition that requires a direct drive speed 400 and 7 AA cells from the 'everything one pound shop', so I don't often catch thermals or stay up long. One time I did it got so high I nearly lost it and ripped the tail off trying to get down.

> Hot wiring gives you lots of options, what kind of airfoil did you use finally?

SD7037 - it seemed popular and I wasn't interested in high speeds, which is something it's not supposed to be good at. After a couple of evenings research I got rather lost and unscientific but it looks OK, and probably more accurate than a balsa wing with sagging film covering.

It did come out much like a Clark-Y - the nice curvy underside ended up mostly flat, partly due to the at the 8" chord and partly due to the tape.
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Old Nov 12, 2006, 04:52 PM
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Quote:
Originally Posted by theBOZman
I started this mod on my Alula last night. Adding that much weight way out there on a sub 4 oz plane doesnt seem too bright though. I'm going to shorthen it up alot to get the battery back on the CG.

My F5D plyon racer was meant to be a sloper. The airfoil was not very efficient "semi-symetrical", so it was religated to a parkflyer. My feathercut will fix the efficiency problem on my next try.

Boz
Boz, that sounds good. Hope the electrification of your Alula works out great - that thing is known to be very sensitive on CG position to fly nice.
PS: actually it was your shrike-alike thread that inspired me to make a motor glider...
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Old Nov 12, 2006, 05:11 PM
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Good news on MOSE-01!!!
Today the weater cleared a bit - the rain clouds were blown away by 50mph(!) winds (...well, about ). Absolutely awful conditions for a maiden flight, especially for such a light model. But patience is not my strength...so I gave it a try.

The wind was so strong that it ripped the plane out of my hand before I was ready to launch. But, off it went climbing 15m in a second ...wow! Turned the nose into the wind and needed 100% throttle to keep it on the spot. Looked much like kite flying... It flew extremely stable considering the conditions.
Control response was pretty good and I was able to counter the heavy gusts.

Can't wait to fly it on a normal day!

Here is the footage that we took ...
http://www.rcgroups.com/forums/showt...86#post6376167
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