True Airspeeds
 

What does everyone average on true airspeeds? Normally Asp and Turbo / P models?

Rising up says mine should averange 167 kt -- which mine does not. Mine is much faster than that -- errr, okay, maybe not.

Rising up says P models should average 204 kt. Is that a close number?

Thanks,

Keven
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SUBARU SAMBAR HISTORY

"Rising up"... is that a website or a book of some sort?

Have you checked your POH Performance section... it should tell you fairly close what to expect with a given power setting. It all depends on loading, ambient air temp and ALTITUDE!

SkyKing

http://www.risingup.com
 

I guess a poor assumption on my part that most GA folks were familiar with http://www.risingup.com and its Aircraft Performance Databases. This web page is a nice beginning point to look up aircraft performance specs. It's not pin point accurate, but let's you know if you're looking at a plane that is in the 150kt or 240kt cruise speed range.

For instance, it gives general information about multiple P model performances, see

http://www.risingup.com/planespecs/i...plane181.shtml

which states a cruise speed of 204 kts for that series of plane.

This website is also cited and linked from Peter's website at:

http://www.skymaster.org.uk/perform.asp

Peter also gives some performance specs, but only for a couple of models, and none of them are T or P models.

I doubt that the Rising Up numbers are dead on numbers because I doubt that all P models have the identical performance data. Again . . . just a beginning point. And since I don't have access to all other 337 model POHs and actual performance numbers, I was wondering what those book numbers were and if everyone was making their book numbers or not.

I know how my plane compares to my POH, but don't know what everyone else's POH says and what everyone else's plane actually trues out at and at what settings. Ergo, I posted the inquiry.

So, with that said, can anyone give me some general performance specs on their aircraft. I'm particularly interested to see what the cruise speed range is between different models of norm asp, and then between Ts and Ps. I'm also interested in at what settings folks fly them, and why you choose those settings / altitudes. An A&P friend never cruises past 65% power because of engine wear. But, that's him and his philosophy. Wondering what other folks do, and why.

I don't want to get into a LOP ROP debate, I just want some general cruising speed numbers to compare models. I searched the site and can't find a previous discussion on it.

Thanks in advance.

Keven
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GYPSIES FORUM

P-cruise specs
 

Keven,

I'll scan a couple of the performance pages out of my 1977 POH for the P-model and post them. However, generally speaking, 2400/31 at 16,000 will net 67% power and about 192 KTAS, give or take on a stock airplane. You really need to be up in the higher rarified air to get the max cruise speeds, which would be FL200, and the numbers appear to be 2500/33" for 75% and 205 KTAS with 159# on fuel flow. Unless you're really going far, it doesn't pay to go that high. We find most of the flying in the 10K to 15K range to suffice, and running conservatively, 180 to 190 KTAS.

SkyKing

Normally aspirated '76G model:

2400 rpm and Full Throttle yields 155- 160K TAS at 50 degrees rich of peak between 6,000 and 12,000.

book values do not seem to match reality.
500 miles san felipe to la paz used 90 gal.
at 10.5k mp=24 rpm 24 and leaned to 12.1 front and rear, no wind/ by the charts that is about only 60 percent of book stats. ok so what am doring wrong??????????

TAS
 

I have a 1975 P337G. My numbers appear to match SkyKing's numbers. Also, Highest I fly is 16,000 feet. Found it not necessary to go higher. Can't go over thunder stroms at 20,000 feet and the additional speed is not worth the fuel cost.

When down low in the 3K to 5K alt. on short hops to breakfast, I average 155 to 160 KTS with 30 inches and 2450 RPM settings.

Jerry

Performance
 

I fly a 76 P-Model. I usually flight plan it for 170 KTAS door-to-door at 29 inches and 2400 RPM (around 65% power depending on temp) at 14,000 to 17,000 ft. The actual level cruise is higher, but the climb is slower and the descent faster, so this is about what I average.

PS: I was doing 240 knots ground speed coming back from dallas yesterday. That was SWEET!

PPS: I would say my bird is typically a little under book, but not by more than 4 or 5 knots.


KT

Kyle's description of performance matched my '73 P model exactly. I used 27" rather than 29", but had intercoolers, which made 27" the equivalent of 29", i.e. about 65% (63 I think) power.

Kevin

Dear Sirs,
Those few of us with the 336 can only marvel at the speeds of our retract brothers.
At 21 inches and 2300 RPM my 336 used to cruise at 142 KTAS
burning a valve conservative 20-22 GPH.
Of course I can't forget to put the gear down, nor can it fail to come down. Annuals are also a lot cheaper and safer without the need to jack the aircraft 6 feet of the floor.
Regards
James T Grant