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A Depron Sea Vixen.FAW2

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Mowerman03/09/2017 14:33:08
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1544 forum posts
105 photos

Hi Simon sad about the first flight crying.

Happy to see you repaired it so quickly yes

Looking forward to the video

Simon Chaddock04/09/2017 14:01:45
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5564 forum posts
2930 photos

A rather poor heavily edited video if its second flight. White underside against a white overcast meant that for over half the video there was nothing to see!

And the landing was a bit of an "arrival" but no damage.

Edited By Simon Chaddock on 04/09/2017 14:03:28

Colin Leighfield05/09/2017 23:35:47
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5975 forum posts
2498 photos

Great result Simon.

Simon Chaddock06/09/2017 15:18:22
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5564 forum posts
2930 photos

Thanks Colin

The bit that I am most proud of is not the build, or even the fact that it flies, but my guess at the CofG position!

McG 696906/09/2017 18:14:20
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2886 forum posts
1091 photos

... I presume your 'guessing' did it again, Simon. wink

... not only for the CoG but also the drawings, 3D printing, cutting, gluing, planking...

... another mega-great 'guess-chievement' anyhow.

Congrats

Cheers

Chris

Colin Leighfield06/09/2017 21:20:59
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5975 forum posts
2498 photos

How close is the c of g to 50% of mean chord Simon?

john stones 106/09/2017 21:55:42
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10821 forum posts
1482 photos

Looks well Simon. yes

Colin Leighfield09/09/2017 22:48:44
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5975 forum posts
2498 photos

Just noticed I said 50% mean chord, I meant root chord.

Simon Chaddock10/09/2017 00:30:17
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5564 forum posts
2930 photos

Colin

I did not actually measure the CofG but simply set it to where it 'felt right' in my hand!

With the intake at the front and a fairing at the rear the true root chord is rather hard to measure but the red line shows where the CofG currently is.

CofG

If leading and trailing edges are extended to the fuselage center line it looks like the CofG would be quite close to 50% chord.

Simon Chaddock20/01/2020 00:02:07
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5564 forum posts
2930 photos

There is a bit more to this story.

Although I had 'tweeked' the wing to balance the wing incidence L to R before it was finished in fact there was some still present. The second flight in the video above required virtually full aileron trim to keep 'wings level'. In such a configuration I feared any flight close to the stall would at best be interesting or at worst result in a serious crash.

I could easily see the problem, the geometry of the inlet duct was different! smile o To correct it was going to require some pretty major surgery. I just did not have the heart to cut up a just finished model so it was left hanging on the wall 'for later'. wink 2

'Later' actually arrived after nearly 2 years - June 2019!

The major surgery required the left wing to be cut completely off just inside the left boom. A narrow 'slice' cut out of the bottom surface of the LH inlet duct and it all reassembled with much masking tape to hold it all in the correct position until the glue set.

One advantage of thin Depron is that when a structure is 'bent' into shape over time it permanently deforms so virtually eliminating any residual stresses.

It now flies quite well and even better when you remember to switch the 'stab' on! wink 2 You can hear the 'click' at 0:17!

Still really only a 'fair weather' flyer but it looks the part and makes a rather satisfying 'whine'.

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