The International Cessna^® 170 Association

hilltop170 wrote:...The 300 Jacobs is a good balance in the Stearman, enough hp to make it perform well and fuel consumption low enough not to break the bank.

I'm not sure "Stearman" and "not break the bank" should be used in the same sentence; even the Cont. 220 would burn 13gph at 80kt. Guess it's all relative...

Agreed, and the Jacobs also burns around 13-14gph at 90mph but that sure beats 18-20gph for a 450hp P&W 985.

Most engines have about the same specific fuel consumption ( HP/lb.fuel )
In same airplane and same flat plate area:
Bigger engine = more HP = faster = more gas.
Bigger engine @ same hp = same speed = same gas.

C-170B w/O-300 @115 MPH @ 9500' MSL = 6,80 GPH Jackson, CA., to Nampa, ID. = 3+45 hrs =25.5 Gal

C-170B w/IO360 @ 115 MPH @ 9500' MSL = 6,85 GPH Jackson, CA., to Nampa, ID. = 3+45 hrs =25.7 Gal.

Above figures from trip logs on N2748D en route to Johnson Creek Airport, ID., from home base.

Yeah but, who runs a P&W 985 at 25% power ????

Jud, I guess we can consider this thread thoroughly and completely hijacked!

miles, doesn't matter, the thread was used for its purpose, besides , can't go wrong talking about biplanes and radial engines!

I'll be heading back next Sunday so I'll try to bring good weather this time...

cessna170bdriver wrote:Jud, I guess we can consider this thread thoroughly and completely hijacked!

At least we waited until you guys were (mostly) through with it before we took over!!!

Miles, "hijacked" is such a harsh word, I like to think we "gently recycled" your thread.

blueldr,
what rpm were you running when you flew from jackson to nampa with io360 engine.

I do not remember what power setting I was using, but at that time I was using a 7860 fixed pitch prop and I flew the airspeed that I previously used with the stock engine. I do not remember what RPM it required, but the HP was obviously the same, or very close to it.
Later on I did change to an 82" McCauley CS prop, as used on a C-182, and I used the power charts from the RC-172 Hawk SP
to develop my own charts.

Dick, ...is that the fixed pitch prop you'd recommend as an "all around" prop? (McCauley 7860) for the TCM IO-360 engine?
Was the switch to a constant speed worth the extra money/effort/weight?

I would have been satisfied with the fixed pitch prop if I had not tried to make it to Masons fly in at Recklaw, TX.,from my home in central CA, that year that it got weathered out. I made it as far as Guthrie, OK, and was stuck there for three days for WX. By then, it was time to go home. That is a pretty long haul each way and I just decided I needed a CS prop for XC trips.
For most of my flying and particularly flying up in Idaho, the FP was fine. It's a good deal lighter and of, course, simpler with almost no maintenance requirements. Up in Idaho, most of the legs are an hour or less and there is always a relatively stiff climb required after take off. A FP prop is, in my opinion, all that is needed for that kind of flying. A CS prop would obviously be advantageous for longer XC flying, and probably would improve the economics too.
I have a friend up in Oregon, Stan Jost, who has what I believe is the first C-170B modified by Tom Anderson with the continental IO-360 engine. He has had the airplane twenty five or more years and has always had a FP prop.
I had, or actually still have, two fixed pitch props for that engine that I believe originally were on a military model of that Cessna Hawk XP trainer. They're both 78" dia. (I think) . One is a 50" pitch the other is a 60" pitch. I tried the 50" first and felt it was too thin and flew the airplane with the 60", which seemed to work pretty well.
I certainly have to say that the Continental IO-360 engine is a perfect fit for that airplane.

cessna170bdriver wrote:

Kyle Wolfe wrote:...it would be dang cold flying that thing here in Minnesnowta. ...

Dad always said the minimum OAT for flying a Stearman is your age plus 20. He sold his just before he turned 73. I guess he figured that even in Florida it wasn't warm enough often enough to make it worthwile...

This is a blanket on which my brother had a photo of Dad and his Stearman put as a gift to our step-mother. Must have been a nice warm day...