Cozy - cvh

Covering home built aircraft using the canard design

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cvh
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#5090

Unread post by cvh » Mon Jul 28, 2008 10:22 pm

Chris,

Where can I obtain the forms that need filling in... ? please.
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Re: Cozy - cvh

Unread post by Beech 200 » Tue Jul 29, 2008 8:17 am

Amazing well done... =D>
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Re: Cozy - cvh

Unread post by Chris » Tue Jul 29, 2008 11:16 am

Initial form and logger info received. Record on its way to be processed.
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Re: Cozy - cvh

Unread post by Malcolm » Tue Jul 29, 2008 12:15 pm

Well done!!! =D> =D>
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#5094

Unread post by cvh » Tue Jul 29, 2008 1:47 pm

Thank you all very much!
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#5121

Unread post by cvh:. » Mon Aug 04, 2008 11:41 pm

Just a quick report on my last flights ...

FASY to FABB around RA and the Ergo slimes dam ... from start-up at the hangar, taxi to 31, turn around, and do circuit, land and taxi to hangar at FABB = 20 min.
Return flight had a slight tailwind ... 17 min door to door.

such fun! never got the rpm over 2500!

:twisted:
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Re: Cozy - cvh

Unread post by ChrisG » Wed Aug 06, 2008 10:15 am

Well done Chris.
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Re: Cozy - cvh

Unread post by Etienne » Wed Aug 06, 2008 3:00 pm

Wow! What an amazing achievement!

2 questions: Mach Tuck usually only happens at M0.82... I'm guessing this was a tongue-in-cheek, but more seriously, is there any section of the Cozy where shockwaves are present at 140kts?
Would a spinner on the back of your prop have much of an effect?
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Re: Cozy - cvh

Unread post by cvh:. » Wed Aug 06, 2008 4:52 pm

Mach tuck ... Marc Zeitlin is our Cozy email list Guru, better than that he works for Rutan himself, the following discussion took place over there ... after which he forwarded the information to us kippies as follows:-
A few times on each of these lists, we've had discussions about going really fast in canard aircraft and the canard airfoil's critical Mach # limitations. Exceeding these limitations could lead to a "Mach Tuck" condition, where a shock forms on the top surface of the airfoil and lift is lost, with a concurrent drop of the nose, and possible lack of recovery.

In a discussion with one of the Proteus pilots today (having to do with a System Safety Analysis), the issue of Mach Tuck came up, and he mentioned that the Proteus experiences Mach Tuck at 0.62 M. I asked how we know this, and he said because he'd experienced it a couple of times.

He said in Proteus (a canard aircraft - closer to a tandem than the VE/LE/COZY, but still a canard) when reaching 0.62 M, the nose begins to drop, the control forces in pitch go through the roof, and you recover by throttling back, putting in full back pitch trim, and having BOTH pilots pull with all their might back on the sticks. The noise level is horrendous, due to the shock wave coming off the top of the canard. As the Mach # slowly drops, everything returns to what passes for normal when flying the Proteus.

So, I don't know exactly how applicable this would be to a LE/COZY/Berkut, but it does tell you that you don't want to go TOO fast, whatever TOO fast might be. IIRC, the estimates of critical Mach # for the Roncz canard were in the 0.55 M range, or somewhere around 370 mph TAS or 320 Kts TAS. This is on the order of 210 Kts IAS at 25,000 ft., which some folks think is doable with a turbocharged engine. Be careful out there.
Experience has shown me that I can quote Marc Zeitlin, with very little fear of being contradicted :D You may try, even air your own personal opinion, but when they start quoting numbers on calculation pads ... :twisted:
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Re: Cozy - cvh

Unread post by Etienne » Wed Aug 06, 2008 7:24 pm

Ok, so the critical Mach number is actually quite variable! But 250kts IAS? :shock: Good luck with that ;)

There was another question: why did the alternator quit on you? Did it come back once it warmed up again?
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#5135

Unread post by cvh: » Thu Aug 07, 2008 8:42 am

When you go that high, all sorts of dragons get out to nail you ... and it was a very interesting learning curve (before I went :-))

air is an insulator, so the thinner the air, the less insulation.
Then you reach a point when that no longer works and it starts arcing ... end of alternator.
Together with the -24,5 temp blasting on this machine, making the various matreials in it's make-up shrink at different rates and "kaput"

same happens with the magnetos, if you are unlucky ...

250 KIAS is not attainable in the Cozy ... I tried :D But if it had, like, a jet engine ...

Now the people they were talking with are not the Mugu variety ... refer credentials of the attendees :D

Have a nice weekend, I'm off!
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Re: Cozy - cvh

Unread post by nat123 » Wed Aug 13, 2008 4:37 pm

Interesting looking aircraft, if it wasn't for the glass cockpit I would have thought the nose was where the prop was attached :?
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#5149

Unread post by cvh » Wed Aug 13, 2008 4:40 pm

On this forum we do have a wooden spoon that gets handed around :)
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Re: Cozy - cvh

Unread post by nat123 » Wed Aug 13, 2008 4:53 pm

Sorry I am a girl therefore the confusion....I am really impressed :wink:
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#5152

Unread post by cvh » Wed Aug 13, 2008 4:55 pm

with the wooden spoon? Its not a broom ... :twisted:

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