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  #1  
Old 07-22-2012, 08:23 PM
gciampa gciampa is offline
 
Join Date: Dec 2008
Location: Fuquay Varina, NC
Posts: 75
Talking RV-7 Service Ceiling - FL 220 Today

All,

while flying back home today, D38 to KTTA decided to test the service ceiling on N269MC;

FL 220 was easily attained, 300 FPM from FL 200 to FL220. Decided the service ceiling for the pilot was FL 220. I was solo, 25 gallons of fuel and some luggage in the back, estimate 1450 pounds at the time.

I snapped a picture at FL200 for posterity.

http://poitras.org/gallery2/v/gciamp...geViewsIndex=1

Gary
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  #2  
Old 07-23-2012, 11:44 AM
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jmjula jmjula is offline
 
Join Date: Oct 2005
Location: Portland, OR
Posts: 188
Default

I look forward to the day I get to do the same experiment 8^). These are great planes!
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  #3  
Old 07-24-2012, 02:42 AM
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Bugsy Bugsy is offline
 
Join Date: Nov 2007
Location: Waukesha, Wisconsin
Posts: 554
Default Dont want to be a stick in the mud

Hey guys,

Just be careful of decompression sickness above FL180 unpressurized for longer than 15 min in an unpressurized cabin. In the Air Force we require 100% O2 on aviators mask above these altitudes. I know plenty of Turbo Mooney oporators routinely fly at these altitudes with nasal canula but I wouldnt for an extended time or if I did I would take precaution.

1. drink extra fluid, best way to dissolve buubles is to add water. Thats why the fizz goes away in your coke when the ice cubes melt. Same thing happens to evolved nitrogen in your body.
2. Above FL180 is no time to practice tactical dehydration. Avoiding water to avoid the pit stop
3. Limit in flight and post flight exercise. What happens when you shake the coke can, more bubbles. Dont end your high alt flight with G maneuvers and dont exercise 12 hours post flight.

Above FL180 you will bubble, normally these bubbles dont stick anywhere and or recompress on decent. Take some easy precautions to avoid aggrevating the problem and enjoy the smooth air.
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Milwaukee, Wisconsin (Timmerman Field)
N377KG - Flying (250 hrs)
RV-7A, Aerosport O-360, WW200RV
Advanced Flight 5400
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  #4  
Old 07-24-2012, 04:08 AM
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NickAir NickAir is offline
 
Join Date: Nov 2008
Location: McMinnville, Oregon: HOME of the SPRUCE GOOSE
Posts: 540
Default Nice report

Quote:
Originally Posted by gciampa View Post
All,

while flying back home today, D38 to KTTA decided to test the service ceiling on N269MC;

FL 220 was easily attained, 300 FPM from FL 200 to FL220. Decided the service ceiling for the pilot was FL 220. I was solo, 25 gallons of fuel and some luggage in the back, estimate 1450 pounds at the time.

I snapped a picture at FL200 for posterity.

http://poitras.org/gallery2/v/gciamp...geViewsIndex=1

Gary
Amazing report. What was your true air speed?? Hope you had o2.
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Working on a RV-4
Citabria 7GCBC
Cessna 180, sold
RV7 I0-360 C/S, Slider, AP, Glass, etc. sold.
RV6 O-320 F/P, Slider, AP, Steam, etc., sold
Citabria 7KCAB rental
Piper Cherokee, sold
Sparrowhawk, sold

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  #5  
Old 07-24-2012, 11:29 AM
gciampa gciampa is offline
 
Join Date: Dec 2008
Location: Fuquay Varina, NC
Posts: 75
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Hey folks,

Yes, I was on O2 as per the regulations. I ended up stair stepping from 12,000, to FL180, then FL200, then FL220 while on O2 to minimize the effects of decompression and evolved nitrogen. A buddy of mine suffered from decompression sickness with severe shoulder joint pain on a high altitude run some years ago.

Refer to the AF3500 image for airspeeds and engine performance.

http://poitras.org/gallery2/v/gciamp...geViewsIndex=1

This was an excellent adventure! Turns out the plane is not as sensitive to altitude as the pilot...
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  #6  
Old 07-24-2012, 12:07 PM
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gvouga gvouga is offline
 
Join Date: Aug 2005
Location: Raleigh, NC
Posts: 113
Default

Quote:
Originally Posted by Bugsy View Post

dont exercise 12 hours post flight.
Any idea why this is true? It seems that by being at high altitude your body would start to reduce the amount of nitrogen in the tissues (by outgassing or absorption in the blood and transfer through the lung during breathing) moving toward an equilibrium state for the given altitude. By going down, your body would just start absorbing nitrogen faster which should prevent the bubbles that cause the problems.

I'm certainly no expert in this field so I'm looking to learn something. Just curious.

My 22,000ft story -

I went to 22k on the way back from KDVK - 5W5 back in May. The Blue Ridge mountains are quite intimidating and I wanted to make sure I gave them plenty of room. I had the standard canulas and an SpO2 meter that I was making sure stayed above 97%.

I can't remember all the temperature details, but I could still climb at 400ft/min up to 22k. I was lightly loaded. I took the same step approach that Gary mentioned up to 22k. Stayed at 22k for ~45min.

Issues
- I started getting vapor lock around 14,000ft during the climb while using my mechanical fuel pump. Once the boost pump was turned on the fuel pressure immediately went back up and all was right with the world. I was running 100% MOGAS (93 octane, non ethanol). Once I leveled off and everything cooled down I could turn off the boost pump and had no issues with vapor lock even at 22k
- No physical issues that I noticed
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  #7  
Old 07-24-2012, 01:47 PM
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NickAir NickAir is offline
 
Join Date: Nov 2008
Location: McMinnville, Oregon: HOME of the SPRUCE GOOSE
Posts: 540
Default AF 3500 performance data

Quote:
Originally Posted by gciampa View Post
Hey folks,

Yes, I was on O2 as per the regulations. I ended up stair stepping from 12,000, to FL180, then FL200, then FL220 while on O2 to minimize the effects of decompression and evolved nitrogen. A buddy of mine suffered from decompression sickness with severe shoulder joint pain on a high altitude run some years ago.

Refer to the AF3500 image for airspeeds and engine performance.

http://poitras.org/gallery2/v/gciamp...geViewsIndex=1

This was an excellent adventure! Turns out the plane is not as sensitive to altitude as the pilot...
Very cool to see your performance data at FL200. Not many of us likely have been there in an RV. Thanks for sharing
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Tailwinds...

Simplicity is the ultimate sophistication.
Leonardo Da Vinci

Working on a RV-4
Citabria 7GCBC
Cessna 180, sold
RV7 I0-360 C/S, Slider, AP, Glass, etc. sold.
RV6 O-320 F/P, Slider, AP, Steam, etc., sold
Citabria 7KCAB rental
Piper Cherokee, sold
Sparrowhawk, sold

Proud -VAF- Supporter - Exempt, Dues Paid Anyway.
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  #8  
Old 07-24-2012, 02:07 PM
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hecilopter hecilopter is offline
 
Join Date: Mar 2005
Posts: 397
Default Fuel flow

Is your fuel flow correct? Are you really burning 8.1 gals/hr at 13.9 inches of MP? Seems really high, I was expecting in the 5-6 range. Good job, thanks for the data!
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  #9  
Old 07-24-2012, 02:36 PM
gciampa gciampa is offline
 
Join Date: Dec 2008
Location: Fuquay Varina, NC
Posts: 75
Default

re: Fuel Flow: In general, my FF reads a tick higher than actual, perhaps a few tenths per hour. I am running an O-360, normal cruise I set EGT around 1400 on the leanest cylinder, around 10GPH on the meter, WOT, 21 MP, 2450 RPM.

However, as I climbed into FL, the engine was not running as smoothly with the leaner mixture setting, lower fuel flow, I ended up setting the mixture a bit richer than I expected.

Also, a critical eye will see one EGT is reading low, this is an erratic EGT probe issue. Sometimes it is spot on, other times it is erratic.
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  #10  
Old 07-25-2012, 09:46 AM
Jimd Jimd is offline
 
Join Date: Apr 2008
Location: Central Iowa
Posts: 317
Default TAS ?

I see 41% and TAS of 151. Even at 41% I would have expected a bit higher true airspeed? What was your fuel economy if you average out the headwind?

Now I see the low IAS, That is a 40 or so difference in IAS and TAS.

Thanks for the post.

Jim
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Last edited by Jimd : 07-25-2012 at 09:56 AM.
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