The International Cessna^® 170 Association

I cruise about 105-108 mph indicated @2450 rpm but I have a 8043 prop. Next week my plane will be getting a Sportsman STOL kit installed, I can't wait! It should make my 650' airstrip a little longer!!

Joe

It seems our planes either indicate 105-108mph or 115-120mph. Are the planes really going that much of a different speed or is the difference in the airspeed indicators or maybe the pitot tubes? Discounting color, what else could make that difference?

The airspeed indicator on 15D has been changed with no effect. It has a 7655 prop, wheel pants, and the 1/4" dia tube pitot. Bending it up and down has negligible effect.

Nobody mentioned what altitudes they were using. The higher the altitude the lower the indicated airspeed will be at any given power setting.

I have turn a 80/43 prop, 8.00x6.00 tires, no wheel pants, 2550-2600RPM usually results in .16MACH.

In 60 year old airplanes, airspeed indicators are about as accurate as tachometers.

FWIW, flying in formation, I was faster than the A model. Agreed on instruments being only so accurate...I have to descend at 1,100FPM to get a true 500FPM descent out of the VSI in the airplane.

Aryana wrote:

Ryan Smith wrote:FWIW, flying in formation, I was faster than the A model. Agreed on instruments being only so accurate...I have to descend at 1,100FPM to get a true 500FPM descent out of the VSI in the airplane.

Something is wrong with that VSI Ryan. Mine is very close to accurate and never reads +/- 50 fpm from the WAAS GPS VSI I have installed.

Mine reads 100FPM sitting on the ground.

bagarre wrote:

Aryana wrote:

Ryan Smith wrote:FWIW, flying in formation, I was faster than the A model. Agreed on instruments being only so accurate...I have to descend at 1,100FPM to get a true 500FPM descent out of the VSI in the airplane.

Something is wrong with that VSI Ryan. Mine is very close to accurate and never reads +/- 50 fpm from the WAAS GPS VSI I have installed.

Mine reads 100FPM sitting on the ground.

This one reads -100FPM on the ground, but if one opens the door, it zeroes out. I'm assuming that the instrument is simply using cabin air for static pressure.

I typically indicate 100 KNOTS (115 mph) at level cruise, 4500 MSL, 2450 RPM, w/ EM7655 prop. (Of course, my Airspeed indicator must have once been installed in a green airplane before it was ovhl'd and exchanged into my red '53 model.)