RC India

RC Models => Electric Planes => Topic started by: bmblb on September 27, 2013, 12:41:07 AM

Title: 6 feet scratchbuilt glider
Post by: bmblb on September 27, 2013, 12:41:07 AM

Hello All !

Here's my 72in span (6 feet) glider. Quick snapshot:

- AUW - 700g
- Wing loading - 6.8 oz/sft
- Span - 72in / 6 feet
- Chord - 8 in
- Fuse - 40 in (prop to TP hinge).
- Battery - 1350-1500 mAh
- Motor - 2212/10 - 1400kv
- Prop - 7x4

Materials used:

Wing: Regular LD t-col, teak wood beading(LE), hard wood main spar, balsa TE, with cardboard center sheeting + brown paper for reinforcements at joints covered with 2in wide packaging tape. 3-1mm Ply braces.

Fuse+Tail assembly: 3mm coro for sides and tail surfaces(TE has one 3mm CF tube running in the flute just before the hinge in TP - not elevator, none in Fin+Rudder ), cross-laminated coro for formers, 2mm coro doublers for fuse sides upto TE.

Title: Re: 6 feet scratchbuilt glider
Post by: FlyingBrick on September 27, 2013, 03:31:25 AM
 :o :o
Looks very nice, please most more close up pics.
Title: Re: 6 feet scratchbuilt glider
Post by: rastsaurabh on September 27, 2013, 09:47:49 AM
Looks damm good ... i am sure it will fly well too. how you've made the Wing !!! Its come out nice.
waiting to see the the flight video.
Title: Re: 6 feet scratchbuilt glider
Post by: manojswizera on September 27, 2013, 10:05:56 AM
Beauty  {:)}

just one question. Are the wings bending downside towards the ends, due to weight ?
Title: Re: 6 feet scratchbuilt glider
Post by: praveen on September 27, 2013, 10:54:32 AM
WOW ,Beautiful! {:)} {:)} {:)}
is this the one you were talking about, on the phone?
Title: Re: 6 feet scratchbuilt glider
Post by: bmblb on September 27, 2013, 11:20:54 AM
here's the start of the wing:

Title: Re: 6 feet scratchbuilt glider
Post by: bmblb on September 27, 2013, 12:06:05 PM
some issue with loading pics...sorry. what is the best format to upload? :headscratch:
Title: Re: 6 feet scratchbuilt glider
Post by: santhosh-r on September 27, 2013, 06:06:23 PM
The best format is jpg...reduce the resolution of the picture for quick and error free upload...taking pics at 3 MP is very good eventhough you have a 14MP cam.
Title: Re: 6 feet scratchbuilt glider
Post by: AnjanBabu on September 27, 2013, 07:18:49 PM
Looking awesome!  {:)} {:)} {:)}
Let me know when you go flying, I have an aeroplane yet to be flown. ;D
Title: Re: 6 feet scratchbuilt glider
Post by: PiyushI on July 14, 2015, 07:11:27 PM
@santosh_r

whats then? curious about the development.

Title: Re: 6 feet scratchbuilt glider
Post by: vishalonline on July 14, 2015, 07:46:02 PM
Good One...!!
Title: Re: 6 feet scratchbuilt glider
Post by: bmblb on December 11, 2015, 02:01:58 PM
.......finally got to fly this one !  In use here is Fuselage #2, with Wing #1....wire cut foam wing.
https://www.youtube.com/watch?v=sMZ0FkEhoE8

Title: Re: 6 feet scratchbuilt glider
Post by: bmblb on December 11, 2015, 02:05:53 PM
After several flights, the wing gave way as I was trying to retrieve it at WOT on a windy day. Needed a wing in a hurry, so built a 6 ft KFm 2 wing.....bottom layer coro.....top layer beady EPS !

EDIT: The broken 6ft glider is now 5ft.....repaired and as good as new  ;D
Title: Re: 6 feet scratchbuilt glider
Post by: bmblb on December 11, 2015, 02:07:52 PM
.....and here's a video of the 6ft KFm2 Wing.....had a blast building it....especially getting symmetrical curved wingtips.

https://www.youtube.com/watch?v=e2LldDHxTGU
Title: Re: 6 feet scratchbuilt glider
Post by: sanjayrai55 on December 11, 2015, 04:43:30 PM
 {:)} {:)} {:)} very nice  :thumbsup:
Title: Re: 6 feet scratchbuilt glider
Post by: bmblb on December 11, 2015, 10:41:22 PM
thank you !

...another interesting observation:

Suitable aspect ratio and the variety of build options considered, my building style has consistently given me finished wings at 50 grams/ft for powered planes of 4ft span and above. I found this reasonably consistent when I verified with a few wings I had....and found it to be useful in estimating the weight of the wings even before I build them.

of course one could make a 4ft span wing ligther than 50x4=200g, and it would be necessary to consider durability and functionality.....and placing the AUW such that the WL is within range.

....also, I found most 3mm coro to weigh about 0.25 g/sq.in and 5-6 mm biofoam/depron (Not foam board) at about 0.16-0.17 g/sq.in( sorry about the units)...

......these may be isolated readings and from a variety 2 to 3 stocks purchased/used over time so don't serve as a benchmark....but the guesstimates have been ok  :giggle:
Title: Re:
Post by: docnayeem on December 12, 2015, 09:44:07 AM
Bmblb.... I second that weight count of coro vs biofoam, but if you consider the added weight coz of paint and or covering ( masking tape , monokote clones etc ) it turns out to be almost the same as coro .
Title: Re: 6 feet scratchbuilt glider
Post by: sanjayrai55 on December 12, 2015, 09:51:06 AM
... and corro has the advantage of fast building, and a degree of crash-resistance. Plus, it's cheaper :D

The only disadvantage with corro is it is difficult to get a precise aerofoil section with it. BTW Bumblebee, what do you use for a spar? I use balsa, 6-12 mm depending on the span, doubled in the centre to approximately 30% of the span
Title: Re: 6 feet scratchbuilt glider
Post by: bmblb on December 12, 2015, 11:17:50 PM
@docnayeem....glad to note that . So far,I have built just one coro wing....folded type...came out at 280 grams, (spars and brace included) for a 48x8in wing....excellent results but a bit heavy.... I have since settled for wire cut foam wings and KF depending on the need.

Rai Sir.....as regards the spars, ....I use teak/hard wood beading ......about 4-6mm thick, 20mm wide....glued vertically.....these cost about 5/- per foot or so.

there's another pressed wood beading available....the grains look parallel and uniform.....and quite tempting to slice into thinner strips...BUT....they DO NOT render the desired strength.

....bamboo is an excellent option for some applications, as long you are able to straighten it.

Teak/similar hard wood beading work just fine and there's a wide range to choose from....there's palm/coconut tree wood variety too.

CF & balsa are reserved where nothing else will work  :)