flying high

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From: John Wright <jwrightdo [at] worldnet.att.net>
Subject: flying high
Date: Mon, 17 Jan 2000 19:45:29 -0700
To: LML <lancair.list [at] olsusa.com>

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Of interest to all Lancair pilots, especially those pressuized is the

article on avweb at http://www.avweb.com/articles/highalt/ entitled When

humans fly high. A few points of interest are rapid decompression above

25,000' resulting in "the bends" and time of useful consciousness and the

effects of CO binding with the blood's hemaglobin. The Payne Stewart Lear 35

crash is reviewed.  After reading this article,  it makes sense to me to fly

in the lower flight levels rather the higher flight levels where we still

get very good true airspeeds and top most of the weather.  John Wright

Colorado Springs



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Flying high

Submitted by Anonymous on

From: Gary Casey <casey.gary [at] yahoo.com>
Sender: <marv [at] lancaironline.net>
Subject: Flying high
Date: Sun, 16 Feb 2014 14:54:44 -0500
To: <lml [at] lancaironline.net>
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Many interesting and informative posts about flying high.  Here's my 2 cents' worth:

1.  I think Bill misspoke when he advocated the use of a pressurized mag above 18,000.  With a naturally aspirated engine the spark plug firing voltage drops as the altitude (and manifold pressure) drop, so it is no more likely to cross-fire at altitude than at sea level.  With a turbocharged engine you have a completely different story - pressurizing the mags is almost necessary.

2.  Any ignition system that advances the ignition timing at low manifold pressure will give a significant advantage in power at high altitude - more so as the altitude goes above even 8,000 feet..  When the altitude gets above maybe 15,000 the advantage becomes huge.  Anyone that is planning to fly long distances at high altitude with a naturally aspirated engine would be foolish not to consider electronic ignition on at least one of the two mags.  My thinking is that electronic ignition on one side is worthwhile from 12,000 to 17,000 and you need it on both sides above 18,000.

3.  Filling your O2 bottle from a welding tank is worthwhile in two ways:  It is cheaper, but also the convenience encourages you to fly higher - a good thing.  All O2 is the same.  The process used to make it pretty much precludes the inclusion of any impurities.  Medical O2 just costs more because of the gov't certifications required.  I bought a refilling system (Mountain High can guide you there) and have a tank in the hangar.  Yeah, it would be good to have two, but it probably isn't worth the hassle, for me at least.  I don't fly that much, but I haven't
refilled in 5 years and I routinely fly above 12,000 feet (usually with only the pilot using from a MH pulse system).

4.  Cooling shouldn't be an issue with a naturally aspirated engine, but it is.  Problem is that most of our planes are probably marginally cooled (mine is) and we usually have a more conservative personal red-line for the temperature (like 400 instead of 450 or so) than in a certified plane.  So, for instance, I usually climb at an IAS above 120 and that works well.  Until I get above 15,000 feet, and then I have to
reduce airspeed closer to the best-rate speed, Vy.  It's that reduced IAS during the climb that causes the trouble.  What to do?  No real solution, but I installed cowl flaps to help out.

It's fun (and safe) to fly high!

Gary Casey