Flying high in a non-turbo

[aaronk25]

I agree the plane flies the same at 110 indicated. Don't remember what the exact climb airspeed was but probably about 90 KIAS, but my J will not climb well at 110 KIAS at 15,000. Not even sure we read 110 in cruise at that altitude. May have been anxiety related to borderline hypoxia or maybe because the climb rate was so slow. Nonetheless it just felt like the plane was twitchy in climb the last couple thousand feet. That's my story and I'm sticking with it.

I also agree with oxygen even at lower altitudes. We feel a lot better at the destination when we use it.

I know the feeling about feeling thing when climb gets pathetic, trying to top the clouds dragging at 200fpm.... After 9500 or so I also decrease airspeed to the 90 or so range to increase climb rate.

At 15k, 2700rpm 30-50rop you should be running 110-112kts indicated in level cruise, which depending on temperature will put you somewhere in the 141-149kts range.

I don't back off rpms much up high as it really kills speed. Also put the mixture where it generates the most airspeed. Kinda interesting but there is ZERO increase in speed by running more than 50rop at 15k. I think that us because of the lower mp and the less dense air takes longer to burn, where down low at higher power settings 80rop generates best speed (not that I use that power setting). Actually I only lose about 1kt by running 20-30rop compared to 50rop but save .5-.7gph.

If some one were really trying to stretch mpg they could run 2400rpm and 25lop at 15k and I bet the airspeed would be 135kts and fuel burn of 5ish-5.2gph.

Pretty awesome airplane, despite our old antique engines.

[Joe Zuffoletto]

I agree the plane flies the same at 110 indicated. Don't remember what the exact climb airspeed was but probably about 90 KIAS, but my J will not climb well at 110 KIAS at 15,000. Not even sure we read 110 in cruise at that altitude. May have been anxiety related to borderline hypoxia or maybe because the climb rate was so slow. Nonetheless it just felt like the plane was twitchy in climb the last couple thousand feet. That's my story and I'm sticking with it.

I buy your story because I've experienced the same thing flying NA aircraft up high like that. It's simple: you're just running out of power and the airframe is starting to tread water. The Acclaim can make 100% power up to 25,000' and has never felt twitchy in climbs at any altitude. Same with the Encore, which is closer in shape to the J. When you're NA at those altitudes, there just aren't enough horses to pull the wagon.

[Hank]

I had 3000+ feet of terrain clearance, and winds were less than 30 knots. Mountain wave was not on my list of expectations that day. I was just passing through.

[Bob_Belville]

I had 3000+ feet of terrain clearance, and winds were less than 30 knots. Mountain wave was not on my list of expectations that day. I was just passing through.

Our lowly Appalachians can have more effect than that. I've been in a downdraft wave with the mountains barely in sight. 

[bonal]

As pilots, Safe pilots we have so many things to always be aware of so many things that can effect our journeys.  On a trip to Santa Barbara flying with my instructor IFR over LAX class B at 10,500 with the marine layer under us had the smoothest air you can imagine with a deep blue sky above felt like I was at the controls flying for South West Airlines. Then we hit the San Gabrial Mountains and Got slammed with a down draft and blew our altitude for a moment but still had enough climb to recover.

FLYING IS SO COOL

[WardHolbrook]

Ok. So it is reasonable altitude to fly 2.5 - 3 hours trip by the East Coast? Or better question is how do you determine your altitude for a trip ( not including the winds aloft calculations) ?

The best way that I know of to find what other guys are doing - routing and altitude wise - between any two city pairs is to look on sites like FlightAware and FltPlan.com. I refer to those site all of the time - there's little point in constantly trying to reinvent the wheel. That being said, it's impossible to properly calculate the most efficient altitude for any given trip without factoring in the winds aloft except for those occasional city pair where ATC handles that detail for you. (For example the SOCAL Tec Routes and the like.)  

Edited August 27, 2014 by WardHolbrook

[WardHolbrook]

I had 3000+ feet of terrain clearance, and winds were less than 30 knots. Mountain wave was not on my list of expectations that day. I was just passing through.

I'm sure you guys have all heard this analogy before, but the easiest way to visualize that the air movement in the atmosphere is to liken it to water flowing in a river. Water flowing over and around a rock or boulder will disturb the water flow for quite a distance downstream. Up in the flight levels we'll occasionally run into mountain wave several hundred miles from the mountain range. The effects of mountain wave can be quite dramatic -  the altitude record for a glider in mountain wave is just under 51,000 feet msl.