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MU 28

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B Sharp
Posts: 750
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: MU 28

Post by B Sharp »

You tell me this after I have already made the crank Rog? I had the alloy sitting there waiting to be used and it cost me nothing and I doubt that it weighs any more than a carbon version.
By the way, I am sitting this evening reading a copy of Airfoils at Low Speeds written by Selig, Donovan and Fraser. I am checking out the polars and lift diagrams of various sections to make sure I have made the correct choice.
Brian. :)

Jolly Roger
Posts: 425
Joined: 30 May 2015, 20:35
Location: Sutton Bank, North Yorkshire

Re: MU 28

Post by Jolly Roger »

The carbon version would be over 40% lighter (size for size) but in real terms you're right this wouldn't amount to much. Maybe drill some lightening holes in your aluminium crank :D

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B Sharp
Posts: 750
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: MU 28

Post by B Sharp »

This morning I finished off the tailplane halves shaping the leading edge and tips and trimming the 1/32 ply root facings. I then spent the rest of the morning covering them with white ‘Oracover’.
I then weighed the original tailplane assembly which came in at 296gm (10.3oz). The new tailplane assembly including joiners and crank were weighed and came in at 162gm (5.6oz) – a saving of 134gm (4.7oz). This saving will mean that I should be able to remove 375gm (13.2oz) from the nose of the model and the whole model will be 509gm (almost 1lb 2oz) lighter overall.
Although I can’t be totally sure of these figures until the model is balanced when complete it is a promising start to the project.
Brian. :)
Attachments
The new tailplane finished and sanded.
The new tailplane finished and sanded.
The old tailplane unit 269gm.
The old tailplane unit 269gm.
The new finished tailplane 162gm.
The new finished tailplane 162gm.

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Peter Balcombe
Posts: 1178
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: MU 28

Post by Peter Balcombe »

Well done Brian, it’s coming along nicely. :)

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Max Wright
Posts: 78
Joined: 10 Mar 2020, 19:57
Location: Clayton Bay South Australia

Re: MU 28

Post by Max Wright »

That's an excellent result, Brian.

AA Elephant.PNG
AA Elephant.PNG (13.81 KiB) Viewed 161 times
Max

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B Sharp
Posts: 750
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: MU 28

Post by B Sharp »

Thanks gents. I have to say that I am finding this whole process very therapeutic.
Brian :)

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B Sharp
Posts: 750
Joined: 19 Mar 2015, 17:18
Location: Perthshire

Re: MU 28

Post by B Sharp »

After my last post I was at the point of fitting the all moving tail (AMT) mechanism into the fin.
I have not been in the workshop for the last couple of days as October time is harvest time and I have been stocking up my freezers and larder for the winter. However my time was not wasted as while I was lifting potatoes I was also planning in my mind the next few steps in the rebuild. I suddenly realised that if I set up the tailplane in the fuselage now I would have no ability to adjust the tailplane parallel to the wing later on and even the slightest difference tends to show. As the joiner tubes, wiring and retainers are mounted solidly in the fuselage any fine adjustments have to be made at the tail.
So as soon as I get a wet day I will start on the wing construction.
Brian. :)

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