The International Cessna 170 Association

Guys, I flew a 170A Friday and I'm concerned about the Rate of Climb. Two adults on board with full fuel, 91 degrees OAT, Indicated Airspeed of 80mph and we were getting only a little over 400 FPM. The owner states a cruse prop is installed. Is 400 FPM normal? I was expecting a bit more, but I'm new...
Thanks,
JP White

JP what was your elevation? My 170 acts similar in Las Vegas when the density altitude is around 5000 feet.

Doug,
The airport was slightly above Sea level. (Just high enough to keep the grass dry)
Thanks,
JP

Onewinglo wrote:Doug,
The airport was slightly above Sea level. (Just high enough to keep the grass dry)
Thanks,
JP

I fly out of W00 which is 168'.

With a cruise prop, your numbers sound about right - give or take.

What are you getting for a static runup? The TCDS says Not over 2330, not under 2230 RPM.
So if you're in that range and making good compression - thats as good as it gets

I swapped to a climb prop and under the conditions you mentioned, I'd expect 500 maybe 600 FPM but the climb prop will chop 5 or 10 mph off your cruise.

I concur that sounds about right. Since I know your looking at this plane to buy and your new at 170s a McCauley 1A170, 53 pitch would be standard, 51 climb and 55 cruise. The plane could also have a McCauley 1C172/MDM which in many circles is a more desirable prop than the 1A170. Another optional prop less desirable than the McCauley 1A170 is a Sensenich M74DR. The pitch for either the 1C172 or the M74DR would be different than the 1A170 if you find the plane has either of these props.

Guys,
This 170A has a McCauley 1C172/MDM 7653 installed.
I'm embarrassed to say I forgot to do a static run-up. (My mentor had told me months ago to be sure I do this.)
The mechanic told me Friday he had the static RPM numbers on file from the August annual. The shop is closed today so I shot him an email asking for them.
Compressions are in the high 70's. 600 hours SMOH.
Thanks again for your input!
JP White

Having a 1C172/MDM muddies the water a little. It has a thinner blade profile and so compared to the 1A170 will spin at a higher RPM for the same pitch. And a slightly higher static RPM is allowed. Many folks take advantage of the higher RPM to put slightly higher pitch into the prop for more speed.

I don't have any personal experience with this prop but talking to folks over the years that do seems to indicate that you can add 1" of pitch over the 1A170 and still achieve the same RPM. So following that rule a climb prop would be 52, a standard 54 and a cruise would be 56.

One thing for sure a 53 is not a cruise prop it is between a climb and a standard for that prop.

I still don't think the performance you saw is out of line.

If you expect eye-watering acceleration and climb rates, the 170 may not be for you. I don't think anyone would claim that it is over-powered.

But, if you learn to live within it's capabilities, you can load it up to gross rate and go thru any mountain pass in the lower 48 states (and over most of the ranges without bothering with a pass.

I find it to be very satisfactory performance. My wife and I just got back from a trip from Indiana to the west coast and back, crossing the Rocky Mountains and the Cascades yet again, with no issues.

I agree, who would not like more power but my O-300 does everything that I need. I took off from Carson City last week at 6500' DA and full gross. Slow climb out but never felt the least bit uncomfortable and was fortunate enough to find 500'/ min on the ridge just to the North. That was the only full fuel takeoff on the trip home and every other field was lower. Full fuel at Friday harbour and I did not even notice the load.

I think the 170 makes a wonderful two place airplane and a competent 4 place airplane.
...but I'm still putting the 210hp and constant speed prop on this winter

I have the EM series and certainly what Bruce stated above is correct... except that a EM (or MDM which is the same blade profile, ...only the hub is different between them).. the EM 7656 will certainly be a cruise prop. In fact, I predict you'll be UN-happy with such a pitch. I have the 7655 prop and it is a cruise prop and I sometimes entertain the idea of going to a 7654 or 53 to shorten takeoffs and improve climbs.

(Also, I wouldn't have to "lug" my engine to slow down for the greenies in this crowd.)

OMG, I had forgotten about those figures that were quoted about the o-300. The best one can do to a 170 is repower it with a Lycoming and see the difference in performance. Yes the fuel consumption on take off is a lot higher but after throttling back I have found the fuel consumption to be the same . I always run lean of peak 50degs) . On a very hot day 100degs plus the runways also seem a lot shorter and the mountains and the trees a lot taller. All engines (normally aspirated) do not produce the power stated and a 180 hp. Engine at 100degs OAT is lucky to produce 135 hp at full throttle . However my rate of climb at 75kts is about 600ft/min with all max up weight .

Put that Continental IO-360 on and you will see a still better climb and cruise and still retain the smooth 6 cylinder like you are used to with the O-300. All it takes is $$$

ghostflyer wrote:OMG, I had forgotten about those figures that were quoted about the o-300. The best one can do to a 170 is repower it with a Lycoming .... .

That's a matter of opinon, of course, but if I were to re-power it would not be with a shaky 4-cyl Lycoming. It'd be with a Continental IO-360 (which puts out from 195 to 210 hp and does so with smooth-running six-cylinders, and which is kinder to the cowling.

Guys thanks for the feedback on the 170 climb rate and the prop education. I have more realistic expectations and can ask better questions going forward.
The 170A I was looking at did not work out, so I'm back on the hunt!
JP White