The International Cessna 170 Association

I have a 170B with O-300, the Horton STOL, and the seaplane prop. With 20* flaps at 5200' elevation it takes 900-1000' to get off the ground (3/4 fuel and two people). At 7500' I can barely get 90 mph indicated out of it. The only thing I can compare it to is a 67' 172 and it was 18 years ago so I don't know if that is reasonable performance or if the STOL kit and or the prop are hampering the cruise performance.

EMB505 , I think something isn't right with your figures. Maybe the ASI is needing a technical wack or the pneumatic lines are leaking . I see totally different figures at that height .

EMB505 wrote: At 7500' I can barely get 90 mph indicated out of it. The only thing I can compare it to is a 67' 172 and it was 18 years ago so I don't know if that is reasonable performance or if the STOL kit and or the prop are hampering the cruise performance.

I am not sure you have a problem. I have an 80/42 prop and usually fly close to sea level at low density altitudes where I barely get 95 mph IAS. Its like I am driving around in 1st gear everywhere but my take offs are short.

Although I generally never fly high, I would have to imagine that even if I leaned it out correctly at 7,500', my IAS would be somewhere in your range. Of course, TAS will increase over IAS about 2% for every 1,000 foot increase in altitude so your TAS will be more respectable.

I have given the ASI the mechanic tap and the needle would jump a couple of MPH. My TAS is only about 95 MPH and that's about what the GPS is showing also so I think the ASI is accurate.

I was thinking I should be doing about 105 TAS.

It definitely feels like 1st gear

I get 105-108 mph with my 8043

Joe

Joe Moilanen wrote:I get 105-108 mph with my 8043

Joe

At what altitude? Do you have aSTOL kit?

pdb wrote:

EMB505 wrote:
I am not sure you have a problem. I have an 80/42 prop and usually fly close to sea level at low density altitudes where I barely get 95 mph IAS. Its like I am driving around in 1st gear everywhere but my take offs are short.

I should have noted that I have a stock wing with VGs, bubble side windows, and 8:50s.

EMB505 wrote:

Joe Moilanen wrote:I get 105-108 mph with my 8043

Joe

At what altitude? Do you have aSTOL kit?

I have a Sportsmans STOL kit. Those #'s were without it, I think I picked up a couple mph since I installed it.