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PSS A-10 Thunderbolt II - another one

1 of 3 1/6th scale Warthogs

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Andy Meade08/06/2015 08:59:04
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2610 forum posts
679 photos

Thanks Steve Although, looking at the weather, Sunday might be better anyway. Are you around for both days?

Phil - get it done!  Would be great to do some formation flying.  The other sixth scale ones seem to have been abandoned.. angel

 

Edited By Andy Meade on 08/06/2015 08:59:52

Steve Houghton08/06/2015 12:11:21
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522 forum posts
342 photos

Andy,

I take my hat off to you for another superb looking model - from one of PSS's true craftsmen. Your models look fantastic to me. I'm just envious of how you find the time for such great work.

Looking forward to seeing the A10 strafing the slope in June!

Andy Meade24/07/2015 13:16:28
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2610 forum posts
679 photos

Sorry to say she didn't fly in June, as Phil didn't order in enough wind laugh

Here is a pic though from the event - that's not a smile, its a grimace of pain from her 37lb weight.

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A couple more from the event :

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Thanks to Dave Gilder / Phil Cooke for these.

So, to make the rear most nose section former a bit stiffer, I added a large 1/4" ply plate, then tried again. Nope, the front-most former on the rear fuselage started to deform then. Great. So I added more 1/4" ply, then added another turnbuckle to keep it together. Problem solved :

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I also swapped out my dual-battery switch to a "green" servo power distribution board, that has two battery inputs. The FRSky RX mounts on top of this, and each servo output is now tripled on the board.

I added a bit of detail to the top of the nose (refuelling plate thingy) and have done some overall weathering, as well as this week added drawn-on panel lines.

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A few more tweaks and re-painting of parts, then she will be coming to Lleyn with me as long as the forecast is favourable yes

Matt Jones24/07/2015 13:23:21
1186 forum posts
1 photos

Looking good but if yours is 37lbs Phil's will be a 50-60lb behemoth!!

Andy Meade24/07/2015 13:27:40
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2610 forum posts
679 photos

I don't know - he builds a lot more accurately than me sad I'm flying a lot of filler!

Ooh, forgot to say, I'm moving the C of G rearwards now too - so hope to shave off at least a pound of lead from the nose yes The balance point on the plan seems (by eye, and online calculation) wayyyy too far forward, so I am adjusting to suit.

Edited By Andy Meade on 24/07/2015 13:27:55

Peter Garsden25/07/2015 06:16:45
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1573 forum posts
1159 photos

Andy - re "I also swapped out my dual-battery switch to a "green" servo power distribution board, that has two battery inputs. The FRSky RX mounts on top of this, and each servo output is now tripled on the board."

Presumably

  1. You have 2 battery inputs in case one fails? And 2 batteries in the fuselage?
  2. If you are using a lipo? What type is it and how do you drop the power down to 6v?
  3. Where do you get the power distribution board? How does it work?
  4. Do you need more power for bigger servos or are you using micro servos - what rating and type of servos are you using?

Don't know why I am asking daft questions because I'm not even building a giant thingey. Just trying to sound in the know and all that.

Andy Meade25/07/2015 07:42:23
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2610 forum posts
679 photos

Hi Pete,

1. Correct! 2 batteries in the nose section.

2. I'm using LiFe batteries, so at full charge they are at 6.6v. They are both 4200 mah.

3. I think I got the board from 4max? The purple power motor people. I have no idea how it works, other than if one battery fails the second takes over. There is no BEC - something I wanted to eliminate to reduce points of failure. I have quite long extension leads so the voltage will be reasonable by the time it gets to the servos. The board multiplies each service output 3 times, so you can run multiple servos per surface if need be. Servo current does not flow through the receiver either - something I was wary of with 6x 14kg torque servos (plus the standard S148s on the rudders)

4. See above! No micro servos at all, but 6 biguns plus 2 normal ones.

you're not building a big thingy....yet

Andy Meade11/08/2015 09:27:46
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2610 forum posts
679 photos

Well, I took the big girl to the Lleyn, and on Sunday I decided it was maiden time, into the teeth of a blustery squall.

It didn't get away. 4 brave souls chucked her aloft for me (great launch guys, thanks!) but alas, she stayed level for a wee while then pancaked the ridge line. I was feeding in up elevator at the time, but it seems just not enough quick enough. All-in-all though, I think it could have been a lot worse if she'd pushed out a bit then pancaked further down.

Damage list as follows :

  • tailplane snapped in half, starboard fin dislodged
  • tailplane mount (dowel plate) dislodged, bracing former cracked
  • various splits in rear of fus around tailplane mount planking
  • Big dent in the A10 teeth on starboard side on the nose, gun and associated hardware torn off
  • ply former torn in half at (new!) tensioner device
  • mating phenolic tube (port side) dislodged / pushed forward (no idea how that happened)
  • nose weight made a bid for freedom through the (admittedly thin) cockpit floor, but was ably stopped by the full-length carbon alignment tube

And that's it. I'd estimate 40 hours work to put right, and I have 6 weeks, so should be easily do-able.

So what's the plan? Put everything right listed above, with a couple of improvements :

  • Move the C of G back to the 5% stability line (equates to about another 20mm back)
  • Seal (tape) all control surfaces from the underside, to make the most of low-speed efficiency
  • Attempt to add a centre-line / C of G area launching handle, within the fuselage, to allow a single (brave, poor) soul to launch single-handedly
  • Add "launch" setting for entire TE, dropping maybe 5 or 6mm if the wind is mediocre
  • Investigate use of a moving sealing plate to eradicate the huge groove left in the wing's bottom surface when the flaps are at 0 deg.
  • Local reinforcements to fus split-line formers & tailplane dowel former; new spruce spar for tailplane; heavy duty cockpit floor in ballast area

I hope all this should end up with the aircraft at least weight neutral, if not actually loosing a pound or two.

More when it happens!

Edited By Andy Meade on 11/08/2015 09:34:55

Phil Cooke11/08/2015 09:55:49
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2254 forum posts
1539 photos

Well done Andy for the brave attempt on Sunday - I'm so glad the damage sustained is fully now accounted and deemed well repairable ahead of the next event on the Blwch.

As you've explained, it wasn't a bad launch, but it's clear we will never get this model to its required flying speed with a hand launch alone, so we need a steeper drop at the launch point to allow the model to fall away as it accelerates to find its natural cruise airspeed. A 40mph wind as opposed to the 30 mph wind we had on Sunday will help no end too, of course. In hindsight, I do wonder if we had run another 10 yards and accepted the fact we would all end up on our backsides trying to stop falling downhill she might have just cleared the lip and got away...

Anyway, some lessons learnt and some good airframe improvements proposed - Good luck with the repair work, we will be watching! thumbs up

Andy Meade11/08/2015 10:10:54
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2610 forum posts
679 photos

Thanks Phil Always need lots of luck in my building! blush

I sort of wish I'd persevered with the same flap arrangement as you, to allow me to have a smooth bottom surface - but I wanted to be able to reflex the flaps a little, mixing them into the ailerons for increased roll response if needed. It wouldn't be too hard to re-create at a later date in all honesty if I want to modify it in the future.

Tim Mackey11/08/2015 13:23:07
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20919 forum posts
304 photos
15 articles

Amen to all Phil said.yes

Andy Meade13/08/2015 11:45:24
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2610 forum posts
679 photos

Cheers Tim wink Hope your birthday went well yes

Repairs coming along well - I am doing those updates on my blog, as it's a lot less clunky to get images inserted into text.

Andy Meade16/11/2015 21:48:00
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2610 forum posts
679 photos

I'll just leave these here....

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David Gilder16/11/2015 21:59:54
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1854 forum posts
656 photos

Fan Bloody Tastic Andy...

If only I had the space and time!!

You gonna let me have the sticks sometime!!!?? lol

Andy Meade16/11/2015 22:03:20
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2610 forum posts
679 photos

Oh...bum. Completely forgot, sorry. Shona told me off in the van for forgetting too blush

Next time for sure!

David Gilder16/11/2015 22:05:07
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1854 forum posts
656 photos

Its fine... I enjoyed seeing you flying it at last..

And loved getting pics of it!

Flyer16/11/2015 22:10:49
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535 forum posts
81 photos

Looks superb Andy. I'm feeling that my efforst are going to be soooo amateur when looking at all these fine models.

(but am aiming to make the 'Orm' next year, with something 'different'....)

Andy Meade16/11/2015 22:11:56
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2610 forum posts
679 photos

yes I like different!

Flyer16/11/2015 22:13:06
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535 forum posts
81 photos

for me 'different' may well be a brick with wings......... least I'll have someting to fly in a hooli...... lol

David Gilder16/11/2015 22:13:29
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1854 forum posts
656 photos

Different makes us curious!!!!!

Speculation time!!!!!

dog

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