A while back I posted that my C-150C, an old straight back model, regularly pegged my VSI while climbing solo. Well, several people politely pointed out that this was pretty unbelievable. So today, I finally went flying with stop watch in hand.

Plane weighs 1025lbs with 3.5gal unusable fuel and 6 quarts oil. I had 7 gal usable fuel on board, myself at 220lbs and 20lbs of survival gear, for a take off weight of 1307lbs. About as light as I ever fly. And temperature on the ground was only 48F.

Well, color me embarrassed, climb from 1,000ft to 2,000ft at 69 mph indicated (published Vy is 71 at gross) took 1:38, which calculates out to a climb rate of only 612 fpm. Well below the published 780 fpm at gross. The entire time my VSI was showing 1700 to 1800 fpm. so should I mark my VSI "INOP" or just 'OPTIMISTIC"?

Phil

P.S. Now that I have the stopwatch in the plane I'll be playing around with different climb speeds to find the true Vy.

AntiCub wrote:Well, color me embarrassed, climb from 1,000ft to 2,000ft at 69 mph indicated (published Vy is 71 at gross) took 1:38, which calculates out to a climb rate of only 612 fpm. Well below the published 780 fpm at gross.

Kid...

Ya shoulda done like I do down here in Nevada on a hot day with this anemic old C172TD/O-300, and density altitudes at 7 to 8 thousand feet... Get out and push!!!!

I'm lucky to even get a positive rate of climb.

Gump

Good for you for going out and doing a little testing. If you would like to do more extensive testing, perhaps to check out your airplanes performance compared to the usually optimistic POH, try this link:

http://www.avweb.com/news/airman/182410-1.html

You will have to register, but they have an excellent article on a technique called the bootstrap method of aircraft performance. It also has a neat spreadsheet you can use to create a data at various conditions of load, power and other non-standard conditions.

tom

Gump, The reason I'm trying to really hone my take off technique and find out accurate performance numbers is so I can fly safely in those high altitudes. I'm planning a trip down to Wyoming and Utah for 2009. To date the highest runway I've ever operated out of was only 1700ft. There just arn't any high elevation runways in Alaska, at least not ones that don't require skis year round.

My standard joke is that my POH was written before truth in advertizing laws.

Phil

AntiCub wrote:Gump, The reason I'm trying to really hone my take off technique and find out accurate performance numbers is so I can fly safely in those high altitudes.

You'll be in for a shock. I went from Kotzebue to high desert Nevada, and it's a whole different seat of the pants world. Only thing that minimized the learning curve is that this is where I grew up and started flying.

Gump