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Design & Build Sport Twin

Sport Aerobat for 2 x 40s

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cymaz04/11/2019 17:25:39
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8812 forum posts
1195 photos

WCL is just about the aerobatic range of 9-10

McG 696904/11/2019 17:43:32
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2714 forum posts
1017 photos

I've been following your build thread since the beginning, Nigel.

... and of course the numerous 'calculations' for your 'peace of mind' and final decisions.

A great self-designed achievement and wishing you the very best with your maiden. yes

Cheers

Chris

Nigel R17/11/2019 08:38:18
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3164 forum posts
486 photos

Thank you gents smiley

 

Maiden day yesterday!

 

First up was the mandatory noise check. Our club has a strict policy of no pass = no fly.

With the Graupner props it was a fail. Not by much but a fail is s fail. Interestingly the direction of the highest reading was from in front so I can only assume the bulk of that was prop noise. From behind it was well within in fact that direction was the lowest reading.

I think one engine would have been quiet enough but the two together...

Anyway I had a pair of APC 11x6 as backups and with those fitted the readings dropped by about 3db in each direction. That was enough to secure a pass so I will run with these props.

Range check ok. Nose up test ok. Controls moving the right way - no more excuses.

Take off was not exactly what I'd hoped for. Of late the runway has been rather wet and a little less maintained compared to its usual immaculate condition. This meant a number of sheep offerings were present and I had to aim between them. This was all good for the first part of take off until a hitherto unseen lump of turd jumped in front of the starboard uc leg and sent the model careering towards the rough at high speed. Abort? No time to think as she bumped the long grass the nose went up and she was away and accelerating rapidly without the drag of the soft muddy strip to slow her.

After getting things back on track by aiming her into a little more gentle climb she was revealed to be pleasantly in trim bar a couple of clicks down elevator. Controls were nicely harmonised. A touch more rudder movement will be needed by elevator and aileron were spot on.

After a few circuits some basic aeros showed good manners and a reasonably good balance point. She would snap and spin with clean recovery. Stall turns were a little slow but a little more rudder will cure that. Inverted needed a touch of down - just right.

The engines need a little tweak I think. Despite the ground tests one started to die back during a stall turn so a minute adjustment needed.

After a few minutes it was time to think about bringing her back down so I flew a couple of circuits at height before coming down for finals. She slowed down beautifully and floated in with no drama. The only hairy moment was when I realised this model is larger than the rest of my fleet and I was about to land the far side if the strip. Open up slowly, go around, line up again, and down for a nice bounce free arrival.

Perfect smiley

All I need to do now is find some spinners to fit the APCs.

Edited By Nigel R on 17/11/2019 08:40:03

Jonathan M17/11/2019 09:19:17
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670 forum posts
275 photos

Well done Nigel - your account of the maiden session was a delight read!

cymaz17/11/2019 09:33:09
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8812 forum posts
1195 photos

Hoorayyyylaugh

Denis Watkins17/11/2019 09:44:23
3932 forum posts
63 photos

Yahooooooyes.

Well done

Piers Bowlan17/11/2019 10:10:05
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1905 forum posts
50 photos

Good news indeed. Congratulations, a well deserved success yes.

Peter Miller17/11/2019 10:12:55
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10320 forum posts
1231 photos
10 articles

Great Stuff!!

Bob Cotsford17/11/2019 16:09:31
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8062 forum posts
444 photos

Now that would make a good 2 part free plan. Keviiiinnnnn! Do we have a Mr Crozier in the house?

Dad_flyer17/11/2019 16:53:30
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167 forum posts
175 photos

Well done yes. It has been interesting to watch the build.

Timo Starkloff17/11/2019 17:18:47
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352 forum posts
787 photos

Congratulations! Not many people get the experience of flying an ic twin. Something unforgettable, especially when both motors are running fine. So good luck for your next flights and keep on training. The more hours, the safer you feel.

Timo

Edited By Timo Starkloff on 17/11/2019 17:19:43

Nigel R17/11/2019 20:25:47
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3164 forum posts
486 photos

Thank you all - that twin sound is something else. I'm dead chuffed with the end result smiley

As Hannibal (nearly) said, I love it when a plane comes together!

Nigel R08/12/2019 07:46:14
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3164 forum posts
486 photos

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Nigel R08/12/2019 07:46:35
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3164 forum posts
486 photos

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Nigel R08/12/2019 07:47:07
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3164 forum posts
486 photos

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Nigel R08/12/2019 07:47:31
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3164 forum posts
486 photos

img_0238 - copy (2).jpg

cymaz08/12/2019 07:52:30
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8812 forum posts
1195 photos

Sweeeeeeeeet heart

Nigel R08/12/2019 08:02:21
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3164 forum posts
486 photos

Had a great day last week, got a few flights in and really enjoying it.

Starboard engine out on flight #1 - no drama, half throttle on the port kept her moving with little rudder correction needed. Came down for an easy landing. Bit of a non-event when it came smiley

The engine had also been reluctant to start both today and when she was maidened, and, this was the one that was a few hundred rpm down on the port engine. I assume that it was also the one that had shown signs of dying back in the air. After the engine out, a closer look revealed that the spraybar had come slightly loose and would have been leaking air, probably more when starting from cold than when hot and running, and making settings unreliable.

With that fixed, I moved to a different fuel as the last gallon had run out, so was due a quick retune, just a couple of clicks, and it was away again, this time no trouble with the motors, they were singing nicely, and confidence grew with the airframe, throwing it through a more enthusiastic pattern.

Lots of power to haul her through vertical eights, inverted maneuvers were all fine with engines running well throughout, in a vertical she pulled straight with no tendancy to fall off left or right, a quick dive test showed CG being fairly close to optimal. Upright snaps all good, knife edge needing a tickle more rudder, inverted snaps maybe a smidge more down elevator to get a clean start. But all in all, no major changes will be needed - so really happy with that. After that, some fast low passes to savour the beat, she moves quick at full chat.

I was lucky enough to have my dad along for a few in flight shots too.

Four flights went all too quick - happy pilot at home time.

smiley

Peter Miller08/12/2019 08:16:38
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10320 forum posts
1231 photos
10 articles

Well done!! Now you really know the thrill of twins!!

Ron Gray08/12/2019 09:02:48
1550 forum posts
367 photos

Excellent Nigel, it really does look good. Now that you’ve got it sorted, next up, retracts!

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