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-   -   RV-10 Service Ceiling (https://vansairforce.net/community/showthread.php?t=131841)

cmgolden 11-22-2015 02:32 PM

RV-10 Service Ceiling
 
I went flying this morning on a cold and beautiful day over Wichita. I headed Northwest and climbed to check the airplane's service ceiling. 40 minutes later I still wasn't quite to the ceiling, but I think I got pretty close.

Cutting to the chase: I flew to 23,000 feet and still had a bit more to go. I could have gone another 1,000 feet without trouble. And I achieved my personal best ground speed coming back: 255 knots.

Details:
On departure I climbed at about 115 kts doing 1,300 feet per minute.
By 7,000, that rate declined to about 1,200 fpm.
At 10,000 feet, I was climbing at 900 fpm at 115 KIAS.
At 16,700 feet, I climbed at 500 fpm (slowing airspeed to 110 KIAS)
At 19,400 feet, I saw 400 fpm (at 95 KIAS)
At 23,000 feet, I was still doing about 200 fpm (95 KIAS)

I had already asked for higher than my original flight plan (FL220) and the controller sounded like he had someone at 24,000 that would pose a conflict if I continued, so I ended my climb at FL230.

When I turned around and began my descent, I benefited from the 77 knot tailwind at that altitude and I achieved my personal record 255 knot ground speed.

Overall, it was an interesting flight.

Jesse 11-22-2015 02:54 PM

I wonder if the EFII system had an effect on the performance and being able to get up that high. I assume you were lightweight, but the highest we have been is almost FL220.

BobTurner 11-22-2015 03:03 PM

Two big variables are weight (sounds like you were solo) and temperature (density altitude). You mentioned that it was cold.

cmgolden 11-22-2015 04:23 PM

Light
 
Indeed I was solo. Outside air temp at FL230 was -24C (which is a bit warmer than standard, I think). I had about 40 gallons at altitude. Density altitude was not quite FL240.

bruceflys 11-23-2015 05:59 AM

Excellent data, thanks. How did you obtain and post such a clear screenshot of the Dynon display?

Jesse 11-23-2015 06:04 AM

There is a keystroke to capture a screenshot from the screen itself. Very useful for this type of thing. I can't remember the keystroke, but it can be done.

Edit: Ensure a USB memory stick is inserted into one of the USB ports and press and hold the #2 and #7 keys.

RV10inOz 11-23-2015 03:53 PM

Interesting flight.

My typical load would be more than that by about 330lbs and at that I have found FL170 is about the limit of "practical" in terms of time to climb, efficiency of the flight etc.

Most of the time FL150 is my maximum.

BobTurner 11-23-2015 05:52 PM

I'll bet density altitude is routinely on the high side?

JDanno 11-24-2015 08:38 PM

Can you tell us what kind of hoops (FAA or others) you had to go that high? Any special training? Had to use a pressure O2 mask? Etc. thanks!
Pretty cool feat of daring!:)

BobTurner 11-24-2015 08:49 PM

Just the obvious things, I think:
IFR rating and ifr clearance
oxygen via mask (canulas limited to 18000') but no pressure mask needed.
(you need a pressure mask when ambient pressure, 100% O2 is not enough. Since sea level O2 partial pressure is about 20% of one atmosphere, you have to go up to where the air pressure is 0.2 atmosphere - like FL400 or so - before you need a pressure mask.)

RV10inOz 11-29-2015 05:02 AM

Quote:

Originally Posted by BobTurner (Post 1032058)
I'll bet density altitude is routinely on the high side?

yeah, it can often be 2000' higher, no different to the USA in summer.

donaziza 11-29-2015 12:14 PM

Quote:

Originally Posted by cmgolden (Post 1031688)
Indeed I was solo. Outside air temp at FL230 was -24C (which is a bit warmer than standard, I think). I had about 40 gallons at altitude. Density altitude was not quite FL240.

Standard temp at this altitude would be -31C, so yeah, you were 7C warmer than standard. Also, and I'm sure you know this already, service ceiling is where you can no longer maintain a 100" per minute rate of climb. Absolute ceiling is where your airplane says Gasp Gasp----I just can't go no higher.:D

jeffkersey 08-07-2017 09:49 AM

OX Mask?
 
Do you have a mask with a mic or do you just pull it away from your mouth to respond to ATC?

bill@fusion4.net 08-07-2017 09:58 AM

At the end of my flyoff of Phase I, the way home from my first cross country trip I did the same. About the same numbers but I did not record them. 23000 feet was climbing at 150-200fpm. Cooling was the limiting factor in the climb.

IFR flight plan, O2 mask, and O2 pulse sensor.

Only time I have been above 15k since. normal cruise is 11,500-12,499 to stay below O2 need.
Pulled my mask to talk to ATC


Fun experience though. Nice Chris

BobTurner 08-07-2017 06:07 PM

Trivia question
 
Quote:

Originally Posted by bill@fusion4.net (Post 1193949)
Only time I have been above 15k since. normal cruise is 11,500-12,499 to stay below O2 need.

Trivia Q: Sometimes you can fly at 12,501' for hours and be legal; sometimes you cannot even at 12,499', because the FARs state "...above 12,500 PRESSURE altitude"...

paul330 08-09-2017 02:40 AM

Just bear in mind that anything over 18,000 risks decompression sickness - "the bends".....

Auburntsts 08-09-2017 05:28 AM

Quote:

Originally Posted by paul330 (Post 1194577)
Just bear in mind that anything over 18,000 risks decompression sickness - "the bends".....

Wait what? Do you have data supporting that? In WWII tens of thousands of airmen went up every day into the flight levels in unpressurized aircraft and I don't recall reading that decompression sickness was an issue.

BrianDC 08-09-2017 07:26 AM

Quote:

Originally Posted by Auburntsts (Post 1194585)
Wait what? Do you have data supporting that? In WWII tens of thousands of airmen went up every day into the flight levels in unpressurized aircraft and I don't recall reading that decompression sickness was an issue.

I was about to scoff at this, but there is a hint of truth I guess:
https://www.avweb.com/news/aeromed/181939-1.html

Auburntsts 08-09-2017 07:33 AM

Quote:

Originally Posted by BrianDC (Post 1194616)
I was about to scoff at this, but there is a hint of truth I guess:
https://www.avweb.com/news/aeromed/181939-1.html

I agree it's most certainly possible and has happened, I'm just not sold on the level of risk below FL250 for RV's as the climb rates at those altitudes are anything but what can be characterized as "rapid ascent". Nevertheless I concede the risk is not zero.

paul330 08-10-2017 07:40 AM

As the article shows, the risk is greatest over 25k. However, I woudn't go scuba diving and then fly at 20k......


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