Cruise Setting for the lowest fuel consumption

[ghostofme]

Hi short-wing team. I have a question about the performance of Pacers / Tri-Pacers.

My goal is to build hours, so the more time I am in the air per gallon of fuel, the better. I'm reading the POH of a PA-22-150, and it shows that at a cruise setting of 2000rpm, I can get a fuel burn of 5.5 gph, versus a fuel burn of closer to 7.5 gph at 2300rpm. That's a big difference in hourly cost when I'm building hundreds of hours.

Would it be fine to cruise everywhere at 2000rpm? I understand I'd be significantly slower, which is not an issue. However, I wonder if this would be long-term bad for the engine. The reason I'm confused is 2000rpm is shown as a "viable" setting on the Fuel Consumption vs. RPM chart I've attached. But I don't know how the engine would like spending so much time there. If this will cause major issues with the engine, saving money on fuel would not be worth the expense of fixing an engine, I'd imagine. Ultimately, my question is, can I consistently cruise the plane between 2000-2100rpm safely?

Thanks

[Subsonic]

YES YOU CAN!!! Go fly! Be free! Build time going slow. Sounds great! Don't ask me what I really think. Yes the engine will be fine. But I question your motives.

If this is what we can look forward to in the experience base of our future ATP pilots, I'm worried. I think we want to hire pilots that know how to go somewhere. Lots of experience taking off and landing at lots of different airports all over the country, so you can show you have experience.

But, to your question, yes you can just putt putt along really slow and be happy with where the wind blows you. Just know the plane was built to go faster and "it wants" to go faster. In other words, it's more efficient in terms of speed-distance traveled vs. gallons burned if it can be trimmed out to about 115 to 125 mph. It wants to go as fast as you can make it go efficiently.

But not you. Nope. You're worried about gas burned vs. hours in the seat. PIC hours.

I shouldn't be commenting but I sense a young pilot here, not experienced with the real world of flying. When I fly, I think in terms of miles per gallon, not gallons per hour. My goal is to go somewhere. Efficiently.

Your objective sounds like you should just be circling in a large diameter circle up high. I have a recommendation: Join the Air Force. Tell them you want to fly very high in big circles conserving fuel for hours. Countless hours. They will have a job for you!!! You can monitor the AI / Autopilot and log all the hours you want! And, never really learn how to fly.

I hope the evaluators of your PIC time in the future look on flight aware and see where you've flown.

Do yourself a favor...At least do simple hamburger runs at 75 mph when the plane wants to 115 mph, so you don't embarrass yourself with your unimportant seat time. People will be looking on FlightAware.

Or, why don't you just go out on the taxiway and putt around and log some time idling around? Who says you have to be in the air? That way, you won't be in the way of airplanes going somewhere.

I'm sorry, but if you haven't noticed by now, I have trouble with this logic.

My honest suggestion:
Try somewhere in-between if you need to be conservative. How about looking for tail winds?!!! That could be fun. Balloon pilots and hang-glider pilots, and real-glider pilots do it all the time, but don't have the luxury of an engine and propeller to get them back home.

Start early in the AM. 6 or 6:30. Go up to an altitude, say 8 or 9k feet and take a tail wind of 40 knots somewhere 100 or 200 miles away and land, have a burger and coke, running at 60% power the whole way. Gas up. Then returning - get back in the air and stay down low (1,000 feet) and take a tail wind home at 65% power. That would be something. Not like sitting in the seat and just biding your time. You would be flying. Really flying.

You could claim you did some real flying and got to practice conserving fuel using tail winds at various altitudes, too.

Use your brain.

-Subsonic

[N2709P]

Running your engine per the POH should be fine as long as your engine is healthy to start with.

Building time is important if you are seeking a career as a professional pilot. Fuel management is something all professional pilots are confronted with. Corporate pilots are trying to save fuel and pick best places to refuel in the interest of due diligence for their employer. Airlines usually leave the gate with plenty of fuel. So unless an airliner runs into unexpected weather or a diversion fuel is not as critical for reaching destination.

Don’t be deterred by a nay sayer. Go fly and manage your aircraft within the limitations it was designed.

~~Marsha

[Subsonic]

Hmmm. You are so positive and supportive, really. Thank you. We need more pilots in this world. It's difficult to say anything to the contrary, but I'll try.

Taxi time on the ground with gate times and all the airport traffic for an ATP pilot flying modern commercial large jet aircraft are real issues wrt fuel consumption. And, they must manage that as best they can to help the corporate bottom line. Time in seat matters, but I'm thinking it's time in a "real seat", not a 4 cylinder fabric covered plane. Please correct me if I'm wrong.

Said directly, I question the applicability of using a Piper Tri-Pacer PIC time to not just aid in the development of that skill set for any pilot, but to improve their qualifications to become ATP pilots.

Last time I took off from a major airport In my Tri-Pacer, my only issue was thinking about the turbulent ground vortices I was going to have to deal with following the A320 that left in front of me.

[N2709P]

The captain on that A320 was probably me.
~~Marsha

[Steve Pierce]

Just be sure and lean the engine. If not, at low power you might not scavenge all the lead out and it builds up on spark plugs and valve stems.

[Frank Green]

Wow sub quite a rant considering ghost didn't even mention why he wanted to build hours. At one time I was thinking the same thing but just so I could get to the 500 hrs. needed to be a QB. Beer and food can motivate. In the RV8 we often cruise at 2000 rpm with the O360 and burn under 6 at 150+ TAS. Made it back from OSH in 3 1/2 hrs. 680 miles on less than 25 gallons non stop yep 40 mph tailwind at 11,500. Over 200 ground speed the whole way. Looking for tailwinds and avoiding headwinds can be fun.

[dgapilot]

While the owners manual says it is OK to run at low RPMs, these engines are designed to be run hard! If you want the engine to last, run at about 2500 rpm most of the time. Short periods at lower power is fine but the majority of the time it should be run hard.

The other thing to consider is that running along at 2000 rpm results in slower speed and a much higher pitch attitude which results in less forward visibility. Flying VFR it is your responsibility to See and Avoid other traffic. Having the nose up going slow reduces your ability to see!

In short, if you sole purpose is to reduce fuel consumption go buy a 65 HP Tcraft, Champ or Chief. They only burn about 4.5gph. A TriPacer properly rigged is designed to fly along at about 130 mph, no straggle along at 90 hanging on the prop.


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[andya]

I second Steve's recomendation

[andya]

I'm also in Dave's camp, Lyc's were made to run hard, I seldom run below 2500 with any Lycoming
I have owned, be it constant speed prop or fixed. Leaning is important to minimize the lead build up.