Pushaire TBD2 - RC Groups
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Apr 10, 2017, 05:35 AM
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Pushaire TBD2


I decided on the Pushaire (see attached) as it was odd and looked like I might be able to make a powered glider from it with a little effort. I scaled the plans up to approx 1800mm wingspan and boy is the fus big and the tailbooms long! I'm thinking of rounding the top/bottom of the fus and doing away with the UC. I may also add a bay to either side of the wing to give me a little more span to play with and I'll double the number of ribs. I'm going to go for the somewhat absurd 'experimental high altitude fighter' look ... which might be Russian in colour scheme as I already have the chinacote!
I am a little concerned about the low hanging rudders and long tailbooms - a lot of load on the wing joint on landing.
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Apr 10, 2017, 06:27 AM
Blueplaidcanard flyer
looks like a real hoot!You may need to sheet the wing out to the booms with 1/64" ply to have it stiff enough to not flex,I had to go that way with a riser 100 wing modified to a twin boom set up.
Apr 10, 2017, 07:25 AM
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It does have a Howard Huges sort of vibe! I was thinking of sheeting the wing on the inner section, which I'll change to an AG35 profile - not too dissimilar to the original in overall thickness and I know it will glide.
I've mocked up a pivot at the front of a boom with the back location to a magnet - not sure it's a good idea. Booms will be thick enough at the wing to have a servo installed. Elevator one side and rudders the other, though linking the rudders will be a challenge.
Apr 10, 2017, 11:16 AM
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JackHiner's Avatar
What is the date of this design?
Apr 10, 2017, 11:34 AM
RFJ
RFJ
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RFJ's Avatar
A Paul Del Gatto design first published in Flying Models, May 1957.

Ray
Apr 10, 2017, 12:04 PM
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JackHiner's Avatar
Thanks Ray
Apr 10, 2017, 02:53 PM
I like real wooden aeroplanes!
Sundancer's Avatar
OK Racemag, I'll post that entry. Looks like an interesting project which should produce a different looking model.
Apr 11, 2017, 07:04 AM
Blueplaidcanard flyer
Held the booms on mine with a hook at the rear and a #6 screw at the front.A bit too much elevator may pop the magnets grip.
Apr 11, 2017, 07:47 AM
So I'M meant to be in control?
Colonel Blink's Avatar
Quote:
Originally Posted by rabidrue1
A bit too much elevator may pop the magnets grip.
Always been a worry for me, which is why I have never held a wing on with magnets instead of rubber bands. If a banded wing lifts off it's seat under aerodynamic forces, the force applied by the bands increases with the distance; with magnets it rapidly reduces. So all the time the aerodymanic forces are lower than the magnetic force it's deep joy. But the second it exceeds the magnetic force, it's goodnight campers and hello terra firma.
Apr 11, 2017, 08:36 AM
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OK, no magnets then!
I am thinking of a CF pin through the front of the boom with a rib either side, then either a 4mm nylon bolt up through a ply plate between the ribs and into the boom, or rubber bands. One thing is certain and that's the fins will come into contact with the ground.
It has a really long nose too - good for balancing but the ol' scale-up and structure issues come into play.
I have the patterns for the formers done.
Apr 14, 2017, 04:35 AM
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Made a start on the fuselage. I was concerned about the contact points on landing - the deep rudders mean the nose will contact every landing, so I made a 'keel' for the bottom of the fuselage from 3mm and .8mm ply either side and naturally drilled it full of holes when it seemed too heavy! The keel, light 3mm quartergrain 'floor' you can see and the bottom planking will for a box section to give some strength to the fuselage when the hatch is cut in the top. Fuselage will be planked with light 3mm and sanded well.

Apr 14, 2017, 07:47 AM
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Started planking and seriously tempted to drop back to the box fus!
Apr 14, 2017, 08:55 AM
AndyKunz's Avatar
Hang in there, when you're done you'll really be glad you kept at it.

A nicely-planked fuselage is a thing of beauty.

Andy
Apr 14, 2017, 09:36 AM
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thanks, box would be a lot lighter! Will need a few more formers.
Apr 16, 2017, 08:21 AM
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added formers and spent this evening sorting out the curves - no patterns for the new formers so best guess and adjustment was the go. Nose block laminated and motor mounted so I can do the rear faring to the spinner. I have to work out how to make the spinner/prop into a rear folding pusher - ideas welcome. Locally some high performance gliders use just a carbon tube to cope with all of the torsional loads and since I'm making this into a glider I thought I'd have a look to see if I could make it work. I'm one of those people who think better with things in my hands, so a 14mm CF tube is on the way. The other option is to just use some flat CF on the spar and sheet the wing centre section.
I've also drawn up some flaps for the centre section - looking at how slow gliders land with flaps down made me think that this would reduce the loads from those damn big fins! Would it be cheating if I flipped them over to point up?