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  #11  
Old 12-13-2017, 03:41 PM
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Dugaru Dugaru is offline
 
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Location: Richmond VA, USA
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This is extremely useful info. I'm going to start heading for the teens on my standard mission between Richmond VA and Allentown PA (about 215 nm). Perhaps the harried controllers in that area will be happy to have me above the fray!

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Originally Posted by airguy View Post
I do it on just about anything over about 75 miles, just because it's so easy to do. For 150 miles or better I just stick it up there to 16,500 or 17,500 and turn on the oxygen. There's virtually no traffic up there, it's cool and smooth, the radio reaches out to forever, visibility is great, and you can glide for a long time on an engine-out scenario which enhances safety.

I don't try to rationalize climbing up there by virtue of fuel economy or time spent in the air or anything like that. I rationalize it exactly the same way I rationalize ownership of an airplane - I do it because I can.
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  #12  
Old 12-13-2017, 03:43 PM
YellowJacket RV9 YellowJacket RV9 is offline
 
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Location: Clearwater, FL / KZPH
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Originally Posted by Dugaru View Post
I'm starting to explore higher altitudes in my (relatively) new (to me) RV-9A. I've got O2. Over what distances do you think it makes sense to climb to 10K or more?
I haven't done the math to find exactly when it makes sense in terms of fuel burn / speed, but anything an hour or longer I am usually up high. Winds aloft could change my decision some though. I have found foreflight's flight planner and altitude advisor to be remarkably accurate once I set it up with my plane's performance numbers.

Chris
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  #13  
Old 12-13-2017, 04:01 PM
pvalovich pvalovich is offline
 
Join Date: Dec 2005
Location: Ridgecrest, CA
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Default Altitude Factors

Couple additional things to consider:
1. Outside air temp. My -8A was designed for 100+ degree summer days in the desert. Heating - even with second heat muff - is marginal at best. I start to get cold soaked with prolonged exposure to below freezing outside temps.
2. The view outside. I just find it more enjoyable to be relatively low.
3. Fuel burn searching for best wind altitude. Sometimes completely negates wind/altitude fuel savings.

But do what you want - because you can!
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  #14  
Old 12-13-2017, 04:04 PM
rightrudder rightrudder is offline
 
Join Date: Mar 2014
Location: Laguna Hills, CA
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Just to add some more data for a typical -9A. Mine's got a 160-hp IO-320 with a Catto 70x70 FP 2-blade prop. Box-stock engine with two magnetos.

At around 11,000 feet DA (where I simply lean the mixture to hit a target fuel flow):

145 KTAS at 7.2 gph
155 KTAS at 8.0 gph
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  #15  
Old 12-13-2017, 05:47 PM
YellowJacket RV9 YellowJacket RV9 is offline
 
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Location: Clearwater, FL / KZPH
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Quote:
Originally Posted by pvalovich View Post
Couple additional things to consider:
1. Outside air temp. My -8A was designed for 100+ degree summer days in the desert. Heating - even with second heat muff - is marginal at best. I start to get cold soaked with prolonged exposure to below freezing outside temps.
2. The view outside. I just find it more enjoyable to be relatively low.
3. Fuel burn searching for best wind altitude. Sometimes completely negates wind/altitude fuel savings.

But do what you want - because you can!
#3 is why I find the altitude advisor on foreflight so useful, and it is generally pretty accurate. If you tell FF your climb airspeeds, vertical speeds, and fuel burns, as well as cruise and descent settings, it takes into account your route and winds aloft and can give you time en route and fuel burn for all different altitudes. Obviously this is based on the data you give it and forecasted winds aloft so it isn't perfect, however I have found it to be fairly reliable. My most recent trips from FL to VA and back it predicted my time en route within 10 minutes each way, and fuel burn within a gallon or so. Of course, sometimes I fly higher even if it takes a bit longer, due to weather, turbulence, clouds, etc.

Chris
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Last edited by YellowJacket RV9 : 12-13-2017 at 05:50 PM.
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  #16  
Old 12-13-2017, 10:34 PM
MercFE MercFE is offline
 
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Location: Maple Valley, WA
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Don't even need to use Foreflight... Can get forecasted winds from aviation weather sources.
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  #17  
Old 12-14-2017, 06:26 AM
YellowJacket RV9 YellowJacket RV9 is offline
 
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Originally Posted by MercFE View Post
Don't even need to use Foreflight... Can get forecasted winds from aviation weather sources.
You certainly can, and that's where FF gets the data from. It's easy to look up the winds at altitude, however FF does the math and can give you an idea quickly if it will be worth the climb, and also your projected ETA's. You can do this all on your own of course, but if you already use FF, it makes it easier.

Chris
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  #18  
Old 12-14-2017, 09:00 AM
MercFE MercFE is offline
 
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Understand and use Foreflight, myself. Saying you don't need anything more than your PPL training to outsmart the "hunting for best wind altitude" gripe.

Quote:
Originally Posted by YellowJacket RV9 View Post
You certainly can, and that's where FF gets the data from. It's easy to look up the winds at altitude, however FF does the math and can give you an idea quickly if it will be worth the climb, and also your projected ETA's. You can do this all on your own of course, but if you already use FF, it makes it easier.

Chris
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  #19  
Old 12-14-2017, 09:43 AM
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PerfTech PerfTech is offline
 
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Default Drift!

....Tremendous thread drift here!....
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  #20  
Old 12-14-2017, 10:01 AM
MercFE MercFE is offline
 
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Years of practice...

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....Tremendous thread drift here!....
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