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Old 06-16-2011, 06:27 PM   #1
imarealslow
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Default depron OB CPO seaplane

43" wingspan, AUW 23 oz (1200mA 2s LiPo) 3mm depron, silver tissue, barbecue sticks.
Any ideas as to exactly what seaplane or conversion is actually used in the escape from the pygmies blow-darts opening sequence in the Indiana Jones film? Loads of controversy on the web, so I just guessed dimensions and went for it. 11 year old Indy fan son was well-pleased with result.
Definitely an approach for the brave, hand-launching a fragile model with a lot of fiddly work behind it into the air with unknown flying properties!Click image for larger version

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Using a rewound Blue Wonder in a fun scale seaplane as seen in Raiders of the Lost Ark. 3mm depron skin throughout with a few ribs on wings and formers on the fuselage. Balsa L/E and curved tips. On the video, it's obvious there is plenty of lift even with a 2s pack and a quick carved balsa temporary prop. that's due to the use of an undercambered profile on the wings and a re-cycled MFA belt drive converted gearbox. It's so easy to get 3mm depron to follow a complicated profile with the help of pre-rolling using - yes, a rolling pin and the edge of the bench! Seemed a waste not to take advantage - designed a slow-speed section with blunt L/E which had Lift/Drag ration about 17! Makes up for all those bamboo sticks!
Incredibly strong - wing spars are 3mm depron and re-inforcement with barbecue sticks into I-beams. All the other sticks go right through the fuselage longitudinal former.
Power measurements on the video notes are reasonably accurate, and it will pull up vertically on 4s (two 2s in series) and 17 X 11 with thrust of nearly three times the AUW. The motor didn't come off, but glue was getting lose on the front bulkhead.
Water-proofed with diluted Polyurethane varnish. Floats and taxis well - although no rudder control = circles at low speed. Easily accelerates on grass, but a little nose-down until over 15mph.
Just waiting for winds to subside and a calm evening or morning to re-check balance and give it a good try out on some aerobatics. Enjoy the crash - photos above taken AFTERWARDS! Never had that happen with 4 pound IC powered models. The debris seen scattering is just bits of the prop.


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Old 06-16-2011, 07:30 PM   #2
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Fantastic job!

Looking forward to more

I think I need a signature.
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Old 06-17-2011, 02:13 AM   #3
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The sea plane sitting at the dock in raiders of the lost ark is a short solent .You can find imfo on a short solent here.http://www.seawings.co.uk/ Here is my solent. I would like to see a depron solent ,i know of one built in spain out of foam . Iam sighned up. My wing is at 5 % pos .the motors are at 1% negetive and elevator at 0% joe


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Old 06-17-2011, 01:02 PM   #4
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Default depron seaplanes

Thanks to you both Larry and Joe.
That's a nice plane Joe, is it a balsa skinned traditional built-up model then?
A motor in each nacelle?
Post some video when you get it launched!

My son prefers the crashes to boring controlled flights. So I've adapted my building to suit his interests - it's a nice challenge after a lifetime flying RC to work out how to put things together without a kit or even plans! See the some of the other scrap/scratch models on my YouTube link.
I keep them all light and slow-flying so he can take over the controls every so often and pick up the skills gradually.
He's enjoyed using a video camera as much as trying to fly in any case.
A good RC modeller should be capable of a nifty quick chuck-glider and trim it out properly anyway - it's all helpful experience, hands-on!
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Old 06-17-2011, 03:52 PM   #5
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Yes it is 3/16 sticks and most of it 1/16 sheeting from ivans plans . All four have 480 hs bb jamera brushed motors and gear boxes in them and 1 esc . Hope you try one in depron. joe
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Old 06-17-2011, 07:06 PM   #6
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very nice plane you need to fly it on 4 cells on 2 cells it wont get out of its own way Take care and have fun, Chellie

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
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Old 06-20-2011, 09:04 PM   #7
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Originally Posted by imarealslow View Post
Any ideas as to exactly what seaplane or conversion is actually used in the escape from the pygmies blow-darts opening sequence in the Indiana Jones film?
I'm pretty sure it's a Waco product, maybe a UBF? It looks like is has the Continental motor, so it might be a UMF without a cowl I guess. Yours looks great!

-Mankind has a perfect record in aviation. We've never left anyone up there.
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Old 05-11-2012, 12:19 PM   #8
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Default flying on 4s lipo from snow

Hi all,
thanks for interest and comments. There is some video here with the model on 4s 1200mah. The plane is still a little tail-heavy - and the 17 x 11 prop had to be trimmed to remove the ragged tips after ploughing into the hedge on a low pass. There is a gusting breeze blowing and the high drag makes precision control of position relative to the ground tricky. Still, way more fun than zooming from horizon to horizon with a small profile foamy on the same motor! Head-cam filming leaves a lot to be desired with the small field of view that the key-fob chinese cameras provide - gives a good idea of whats possible with this kind of junk-box model though! Amazing how it has survived a quite a few major prangs and landing stall nose-dives.

http://youtu.be/w8R8YbqRJb0

enjoy,
Mark
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Old 05-11-2012, 02:24 PM   #9
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Looks like my kinda of flying its called willy nilly.lol Nice looking plane ,you will get the bugs worked out and she should fly fine. A 17x11 prop ? joe
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Old 05-11-2012, 07:49 PM   #10
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Mark, its hard to tell from the newest video but I dont think your tail heavy.

If anything it looks nose heavy to me. You may also need some more down thrust in the motor and its also possible you have to much decollage.

Any of those can cause that porpoising flight pattern - every time the model speeds up, the nose comes up and almost stalls, then repeat.

You might try working your way through this trimming guide and I'll bet you end up with a much better flying plane.

http://www.palosrc.com/index.php?opt...1:ic&Itemid=50

I think I need a signature.
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Old 05-11-2012, 08:52 PM   #11
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Originally Posted by Larry3215 View Post
Mark, its hard to tell from the newest video but I dont think your tail heavy.

If anything it looks nose heavy to me. You may also need some more down thrust in the motor and its also possible you have to much decollage.

Any of those can cause that porpoising flight pattern - every time the model speeds up, the nose comes up and almost stalls, then repeat.

You might try working your way through this trimming guide and I'll bet you end up with a much better flying plane.

http://www.palosrc.com/index.php?opt...1:ic&Itemid=50
I agree with you larry about it might need down on the motor or the incidence on the bottom or top wing could cause this also ,dont ask how i know that. lol The club site for trimming a plane you put up is a club i have flown at for warbird meets for over 30 years Larry.There are 3 or 4 clubs flying off of the same field ,it makes all their meetings kinda fun to watch.lol joe
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Old 05-12-2012, 12:27 PM   #12
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Originally Posted by Larry3215 View Post
Mark, its hard to tell from the newest video but I dont think your tail heavy.

If anything it looks nose heavy to me. You may also need some more down thrust in the motor and its also possible you have to much decalage.

Any of those can cause that porpoising flight pattern - every time the model speeds up, the nose comes up and almost stalls, then repeat.

You might try working your way through this trimming guide and I'll bet you end up with a much better flying plane.

http://www.palosrc.com/index.php?opt...1:ic&Itemid=50
I'll agree with that Larry. I have an HE51 that has at least what should be the positive stab incidence that the biplane requires, and it's still a climber. Decalage is near zero, with a slightly higher degree of incidence on the top wing. Excessive positive incidence on the lower wing on planes with positive stagger (or wings, such as on my Guillows DR1) will cause a porpoise stall cycle. I corrected the CR1 somewhat and it is much better. Earlier flights were literally like a roller coaster.

I went back and forth with someone who wanted to insist the HE51 was tail heavy, but it isn't. I'm about as conservative as it gets with forward CG setting. Once trimmed it flew beautifully, to the point where the trans could have been handed to a complete beginner. Without tearing the stab out, which I won't do, the plane would probably benefit from a few degrees of downthrust. Now that I know what power level to launch at (almost none) I should get back on it, as it was one of the smoothest flyers I've ever flown.
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