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Old Aug 09, 2004, 07:33 AM
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Asymmetrical AP-plane out of depron


Hi everybody!

Just started building a 480-sized plane for aerial photgrophy. I know, it should be posted under AP but it's made of depron mostly so here it is.

The idea is to separate the "aeroplane-part" from the "camera-part", minimizing vibration-induced distortion in the pictures. Hence an asymmetrical plane looking like the Blohm & Voss 141 from WWII. I was hoping the depron might absorb some vibes as well.

Anyone tried this before?

Specs:
Span 1200 mm (47.2")
Cord 300 mm (11.8")
Wing area 36 sqdm (558sq")
Length 820 mm (32.3")
Weight approx 650 g (22.9 oz)
Speed 480
cells: 8 KAN 1050 mAh (180 g, MUST go for LiPo!!!)

Building technique is similar to a balsa model, ailerons are cut and faced similar to a BalsaCraft model.

More pix will come...

/Patrik
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Old Aug 09, 2004, 08:31 AM
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Looks good!
Is the last photo part of the pod?
Looking forward to hear from the maiden.
/Stefan
Old Aug 09, 2004, 03:07 PM
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hey Century,
Nice work, looking forward to the maiden! P.S. the banana peel goes in the trash!
KEEP BUILDING---JIM.
Old Aug 09, 2004, 04:54 PM
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What a cool idea - asymetrical! I never would've thought of that. Looks great so far. Hope it works, good luck!
Old Aug 10, 2004, 03:44 AM
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Jim, no time for carying trash, building only!

As for the idea of asymetry, I really can't take any credit. Check the Blohm&Voss 141!
It is an interresting thing considering the following: our props rotates CW in the direction of flight. This produces a propwash over the fin which turns the plane to the left. To counteract this you can either build your fin (vertical stabilizer) canted a few degrees, or trim with the rudder (if you have one) or move the thrustline to the left (producing a right-turning torque).
Ideally, the asymetrical thrust-induced torque should balance the propwash torque under power. With the motor off, the drag of the camera pod should balance the draf of the fuselage. Ideally!!! Then there is the question of center of gravity...

As for the last pic, the campod. You're seeing it from the bottom and the front is to the right, still lacking a nose cone. The cam mounting plate sits between the two bulkheads.

Anyway, more pix: first one shows the battery tray from below, second one is the rear fuse with depron bulkheads.

Later Dudes!
Old Aug 11, 2004, 03:58 AM
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More build-pix:
1st: Slots in the wing are for the campod balsa tongues. The hole is for the aileron servo.
2nd: Campod with rear balsa tongues, they stick out about 15mm and glues into the slots in the wing.

As I went to bed I just realized how over-engineered this really is! A better way would have been to insert a couple of dowels, front and rear, in the campod and secured it to the wing with a rubber band! I mean, if a fuse can be held to a wing with rubber bands, a 2 oz pod might just stay attached! Duuuh, me and Homer Simpson...
Old Aug 12, 2004, 09:58 AM
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Late last night I closed up the wing, top skin glued. Should have taken a photo but that would just have shown a massive white blob w/o contures or anything... I'll post a pic when I've cut out the ailerons and glued the LE and TE.

This morning my 20 month old son, Oscar, found some depron left overs and promptly started building and making aeroplane noises!!! We had a bit of dep-bashing and made a 5-minute delta he could toss around. Great stuff!

I keep telling people I really haven't tried to make an aviation nut out of my son, but nobody believes me! Strange...

/Patrik
Old Aug 12, 2004, 11:20 AM
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Now Century, all you have to do is buy him an brushless combo and some good radio gear...
Who knows. Maybe you can borrow his LiPo pack from time to time :-)

/Stefan
Old Aug 12, 2004, 10:08 PM
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Looks great - I use the same basic construction method for my depron/fanfold wings. I really like the way they turn out.
Old Aug 13, 2004, 04:16 AM
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More late hour work last night. Cut out the ailerons and prepared wing for LE and TE. Edges will be of balsa mostly as a vaccine against hangar rash .

Aaah, I can almost smell the maiden flight...

/Patrik
Old Aug 13, 2004, 05:37 PM
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Hey Patrik, great idea for a Ap plane!
From looking at your drawing though, have you considered offsetting the horisontal stabilizer too so that it is centered on the wing? The B&V had this IIRC, and I fear you may experience some rolling tendencies with the stabiliser set up as per your plan, because it will be acting more on one side than the other.

This may not be a problem, I certainly am no expert on assymetrical planes, but in theory at least you might encounter a problem.

Good luck!
Anders O
Old Aug 14, 2004, 02:20 AM
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Don't forget to check out Burt Rutans "Boomerang". It would make a great model too if you could actually find some drawings on it......

Brad
Old Aug 15, 2004, 10:56 AM
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Hi Zero!
Yeah, the stabilizer should have been asymetric as well. As it turned out the fuse is so much heavier than the pod so the offset will only be 25 mm. If I ever build the serious version (3 m span, AUW 5 kg, SLR camera etc) the stab will def be way off center!

Arx, I'm actually drooling over the Boomerang as it's a great assym concept ! They would really scratch their heads at the flying field over that one... As a flat plate design this winter maybe, hmm, yesssss!
Last edited by century_series; Aug 16, 2004 at 05:01 AM.
Old Aug 16, 2004, 05:07 AM
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Slow weekend, not much built.
Well, I had my sister in-law and her son visiting so... BTW, my in-law is a police officer so she can't very well be an out-law, can she (pun intended )?!

Managed to tamper a bit with the camera tray though.

/Patrik
Old Aug 16, 2004, 12:44 PM
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Watch out!
I think that bananapeel is stalking you...
/Stefan
Btw, building looks great!


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