Dan Olsen wrote:
Greetings,
As I build my IV-P kit, I’m always watching with anticipation the other IV-P planes out there and how you guys are using them. One thing that has struck me is that it appears most of you with piston IV-P’s are flying them around in the
low- to mid-teens rather than in the flight levels. I’m curious why this is the case… Trips not long enough to justify the climb? You want to stay VFR? Performance or handling issues up high? Etc.
Would love to hear from some of you on the operational practicalities of using your IV-P as a X/C traveling machine. My expectation is that I’ll be using mine a lot on lots of 1,000nm X/C flights and am planning to fly in the FL220-FL250
range.
Thoughts?
Dan,
I am one of the IV-P builder/flyers that you describe below. I tested N437RP to FL 250 and have had it up there
several times over the past few years, but I generally fly in the high teens/low FLs for several reasons. First is the pressurization. I lost a canopy in an AF F-4 Phantom at FL 280 many years ago, and I’m pretty sure that if we ever lost a window up high,
my wife would not get in the airplane again…and that’s important to me. We also like to fly 2-3 hour legs, even on long cross country flights, so climbing way up is usually counterproductive WRT fuel burn. Having said all that, the ability to go up high is
VERY useful, and I’m really happy to have the capability…when warranted. For example, we launched from Phoenix, AZ enroute to Manassas, VA last year. The winds at FL 210 were 100 KTS, almost on the tail. At FL 230 they were 120 KTS directly on the tail. We
climbed to 230 and went all the way home without a stop…fastest this airplane has ever passed over the ground! I considered FL 250, but the winds were not quite as favorable.
Second issue is weather, and this tends to drive you higher in most situations. You won’t top TSMS in a Lancair,
but you can almost always climb high enough to get above the “prevailing clouds” to see the real threats… and above about 15,000 they tend to be isolated and easy (in a Lancair) to avoid. After an
incident in NC a couple of years ago, my wife won’t fly cross country without our Garmin 696/XM weather…which I can highly recommend. There are several alternatives to XM WX now, and I’d strongly encourage you install one of them. The reason is that
these airplanes have the range to fly through two or more weather systems during a typical cross-country trip, and the speed to fly around almost anything along the way…if you know about weather along the way and can keep updated. ATC has become much more
involved in helping GA aircraft avoid weather in recent years. While ATC is very good at this, they provide weather avoidance as a second priority to their ATC duties; it’s really assuring to be able to monitor and confirm their recommendations, or to ask
well ahead of their recommendation for a 10 degree heading change… You’ll also find ice in the cloud tops at any time of the year…higher in summer, but even in August, the freezing level is below FL 250. I’ve gone to FL 250 several times, when we planned to
cruise lower, to stay out of the cloud tops. Works well for me, and is a very useful capability.
There is very little air traffic in the high teens—most GA aircraft don’t want to bother with oxygen, but by
the low flight levels, you’re mixing with some of the small regional carriers. It’s really not too bad, but 15,000 to FL 200 is almost devoid of “cruising” airplanes…I usually suspect another Lancair if I hear someone at these altitudes…
My airplane handles very solidly and reliably up to FL 250; this is not an issue at all for me. Ditto for the
power to climb that high. My engine CHT’s run the hottest (around 400 degrees) when climbing through 14,000-17,000. If any cylinder goes above 400 during the climb (full rich/WOT/160KIAS), it’s a reminder that I failed to turn on the low boost (recommended
by Lancair, and my personal experience). The small amount of additional fuel flow cools the cylinders back down, if it’s a particularly hot day up high, a bit more airspeed does the trick, but I never run my engine at CHTs above 400, although I recognize this
is well below the 460 limit specified. Once above about 17,000, the cylinder temps start back down. I suspect that this is the “critical altitude” for my engine…where the
turbos are producing max boost and the power starts falling off with increasing altitude? (Would appreciate thoughts of others on this observed phenomena)
I predict you’ll be very pleased with your IV-P as a long distance cross country machine, no matter what altitude
you fly. The cabin is relatively quiet when the door seal is inflated, and a 4-hour flight at any altitude above the turbulence layer is as comfortable and relaxing as watching a long movie. Try this while breathing O2 through a mask or cannula at FL 180 in
a “regular” GA airplane and you’ll be wasted…or at least tired. I consider the pressurization to be the best feature of my airplane after the very reasonable fuel burn for the speed!
If you’re as old as
I am, a pee bottle, or alternative, is almost mandatory for long flights, but the bottle works for me, and I’ve been across the country (Manassas, VA to Ridgecrest, CA), both ways, a number of times with one mid-country fuel stop. A fuel burn of 14 GPH
(LOP) will yield 210 to 260 KTAS depending on cruise altitude; that’s almost 7 hours endurance in my airplane (depends on your fuel capacity and how high you climb after takeoff). So, the really nice thing about a piston powered, pressurized airplane is that
you can chose the optimum altitude for your mission, and arrive comfortable and refreshed! …my best short summary.
Glad to talk to you directly about this if desired.
Bob Pastusek
757-286-4802
…a believer!