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  #31  
Old 12-17-2015, 01:44 PM
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airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
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The flight-aware track shows climb rate was variable near 100 fpm there for the last 1000 feet, the engine can't make power, the prop can't make thrust, the wing can't make lift, this was maxed out.
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Greg Niehues - SEL, IFR, Repairman Cert.
Garden City, TX VAF 2020 dues paid
N16GN flying 700 hrs and counting; IO360, SDS, WWRV200, Dynon HDX, 430W
Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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  #32  
Old 12-17-2015, 02:59 PM
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Bill Boyd Bill Boyd is offline
 
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Location: Landing field "12VA"
Posts: 1,530
Default Absolute ceiling

... that place I've never visited where Vx, Vy and Vs1 all come together on the airspeed indicator. Also known as coffin corner for trans-sonic-capable aircraft, but not so much for RV's.

I bet the air is fresh and bracing up there.
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  #33  
Old 12-17-2015, 03:38 PM
Bill Dicus Bill Dicus is offline
 
Join Date: Jan 2005
Location: Shorewood, WI (Milwaukee area)
Posts: 1,066
Default 28000 plus!

I thought coffin corner was where stall and limiting mach intersected. The mach number for this flight wasn't very high, but I have no idea if the RV-8 even has a limiting mach. Anybody?
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Flying Pitts S-2A, Piper Lance
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  #34  
Old 12-17-2015, 04:59 PM
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nigelspeedy nigelspeedy is offline
 
Join Date: Dec 2008
Location: Tehachapi, CA
Posts: 154
Default 0.172 Mach

Not sure where the RV-8 runs into Mach buffet but probably higher than Mach 0.172.

When slowed to 55 KIAS the stall warning started to come on and at 65 KIAS it was descending, so a narrow workable range. The plane flew just fine though. If you are happy with slow flight at sea level you would not be surprised by the handling when flying slow at altitude.

I set the prop once when I started the climb and it didn't change by more than 10 RPM on the way up or down.

At 20,000' the fuel pressure started to drop so I put the boost pump on until I was below that altitude again.

Cheers

Nige
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  #35  
Old 12-17-2015, 05:22 PM
Darren S Darren S is offline
 
Join Date: Apr 2009
Location: Canada
Posts: 439
Default Ok please educate Me the dum dum

Mach limit? What the.....? Please explain.

And Ya, how do you stay aloft if the IAS is 38? What was the TAS again?

As Slider said, "Gutsiest move I ever saw, man!" And may I point out that you got the cooolest last name ever! If that's really your last name😊
For those who don't know who Slider is, shame on you!

Forget this Star Wars business, I'm camping out for 12 days when Top Gun 2 comes out!
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  #36  
Old 12-17-2015, 05:28 PM
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smokyray smokyray is offline
 
Join Date: Jan 2005
Location: TX32
Posts: 1,891
Default Into thin air...

Quote:
Originally Posted by nigelspeedy View Post

Some observations. It's bloody cold up high. Aluminum is a great conductor of heat. Pens and iPhones don't work very well when cold. The RV-8 cabin heater is no match for -40C. The Dynon Skyview system stops reporting OAT below -32C.

The flight was spoiled by being passed as traffic to a jet climbing out of China Lake as "a very slow moving RV at 280". Granted 38 knots ground speed is a little on the slow side for an RV.

These planes really need a blower or turbo to increase the shabby high alt performance.
Nigel,
Many moons ago I nursed my very lightweight, carbureted 150HP "wood propped wonder" RV4 The Bandit to FL200 (no heater) and realized your realization 20 years hence! With water bottle frozen solid and chattering teeth forcing a retreat to thicker air I descended post haste. From many altitude chamber briefings and physiological systems classes, venturing above FL250 is inviting trouble without proper training or equipment. Nuff said.
Like you I have spent many hours above FL400 and Six Bills over the ground, fat dumb and happy in a modern pressurized Jet. However, I always marveled at those who went before.

Wiley Post zoomed the Winnie Mae Lockheed Vega to 51,000' in the early 30's and LTC Mario Pezzi somehow coaxed a blower equipped Caproni Biplane to 56,000' in 1938! Joe Kittenger jumping out of a balloon from 100K over 50 years ago....the list goes on.
I've often wondered what it would take to break Pezzi's record. Easy answer, lots of money. Bruce's Exxon Tiger basically a souped up RV4/HR1 topped out at just above FL400 with a supercharged fire breathing IO-540. Personally I think the way to attack it (RV wise) would be a very light weight RV12 with a Rotax 914, turbo Revmaster or blower equipped RV9 with a donned pressure suit and an aux heater.

Over the years several RV guys have experimented with blowers and turbos. I even experimented with a 12V electric leaf blower on my RV4, with not much success.
But I digress.

It could be done...

V/R
Smokey

Last edited by smokyray : 12-17-2015 at 05:32 PM.
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  #37  
Old 12-17-2015, 06:16 PM
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n5lp n5lp is offline
fugio ergo sum
 
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Location: Carlsbad, NM
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Nigel's great flight seems to be aimed at determining what the aircraft is capable of with no atmospheric help, but when it comes to records I always wonder why pilots don't take advantage of free help.

I noticed today that the Perlan II glider took up residence over the way from Paul and Louise's and others spots. So this is an efficient airframe with no engine, that is expected to be able to reach an altitude of around 90,000 feet. Yes, with no engine they expect to be able to fly higher than any air breathing aircraft has been able to go.

As noted above, I have been to 30,000 feet with no engine in quite a crude glider with low performance. That makes me feel sure that an air breathing engine powered airplane should be able to gain at least another 10,000 feet or so by using atmospheric lift.

So, while wondering why this free aid is not used, other than the increased trouble of waiting for the right conditions in the right area, I also wonder how much benefit there would be. The glider generally has more efficient aerodynamics but the powered airplane has the help of the engine that becomes increasingly less helpful with altitude. There is a crossover point that I am not near smart enough to figure out.
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  #38  
Old 12-17-2015, 06:47 PM
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N941WR N941WR is offline
 
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Location: SC
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After flying the -9 for a few years, I started to wonder what Bruce B. could do with the Tiger, if fitted with -9 wings.

For those of you who have not had a chance to fly the -9(A), the wing is simply amazing!
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RV-9 (Yes, it's a dragon tail)
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Build the plane you want, not the plane others want you to build!
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  #39  
Old 12-18-2015, 12:08 AM
paul330 paul330 is offline
 
Join Date: Feb 2007
Location: Mpumalanga, South Africa
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Thanks for your explanation, Nigel. I can see you carefully thought it through and have had the necessary experience/training to do, what I assume, was a test flight "to see if it was there" rather than advocating it as a way to get from A to B.

The only problem is that other less capable people may be tempted. A lot of questions that have come up show that high altitude flight is not well understood by some.

May I just add a word of caution - "Don't try this at home...."
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Mercy Air, White River FAWV
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  #40  
Old 12-18-2015, 01:06 AM
BobTurner BobTurner is offline
 
Join Date: Dec 2011
Location: Livermore, CA
Posts: 6,797
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Quote:
Originally Posted by Darren S View Post
Mach limit? What the.....? Please explain.
Many transport catagory aircraft are not designed for any supersonic airflow, e.g., if the air over the wing goes supersonic shock waves may be set up preventing the ailerons from working properly, the center of lift may suddenly change, etc. So there is a "red line" not to be exceeded. Since the airspeed over the wing is faster than the airplane's speed, this redline has to be less than Mach 1, often like Mach 0.85. This is a True airspeed, and is the "Mach Limit".
At the same time, stall speed depends on indicated airspeed. If you are flying at (true) speed Mach 0.84 and climbing, the indicated airspeed eventually gets so low that it approaches stall speed. This is the "coffin corner"; any slower and you stall (bad), any faster and you exceed Mach 1 on top of the wing (bad).
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