A Question about FP prop on injected engines

islandmonkey · #1 03-11-2010, 10:07 AM

I have flown a number different types of aircraft with VP propellers that were turned either by carbureted or injected engines. However, I have never flown behind an injected engine turning a fixed pitch propeller. Is there any reason why fixed pitched propellers and injected engines are not mated together more often. I have searched through the forums to try and answer this conundrum but have come up with no answers.

Sid Lambert · #2 03-11-2010, 10:23 AM

No, it's just a cost thing. The 172SP is injection and fixed pitch.

islandmonkey · #3 03-11-2010, 10:35 AM

Thanks Sid.

Greg Arehart · #4 03-11-2010, 08:55 PM

I'm flying an IO-360 with FP prop and it works just fine.

greg

cguarino · #5 03-13-2010, 09:47 AM

I have an AEIO-320 with a Prince P-Tip.

Sam Buchanan · #6 03-13-2010, 10:06 AM

Quote:

Originally Posted by islandmonkey

I have flown a number different types of aircraft with VP propellers that were turned either by carbureted or injected engines. However, I have never flown behind an injected engine turning a fixed pitch propeller. Is there any reason why fixed pitched propellers and injected engines are not mated together more often. I have searched through the forums to try and answer this conundrum but have come up with no answers.

Anthony,

I suspect the reason you see more injected engines with CS props is due to the builder wanting to extract maximum performance from his expensive engine. There is no reason why a FP prop won't work fine on any of our RV engines, and they have been installed on every model of RV many times regardless of engine used.

It really comes down to which has higher priority, max climb performance or minimal periodic maintenance and lowest possible cost.

P.S. I edited the title of your thread so it will be more descriptive for the search engine.

David-aviator · #7 03-13-2010, 10:50 AM

Quote:

Originally Posted by Greg Arehart

I'm flying an IO-360 with FP prop and it works just fine.

greg

Same here.

L.Adamson · #8 03-13-2010, 11:29 AM

Quote:

Originally Posted by Sam Buchanan

Anthony,

I suspect the reason you see more injected engines with CS props is due to the builder wanting to extract maximum performance from his expensive engine. There is no reason why a FP prop won't work fine on any of our RV engines, and they have been installed on every model of RV many times regardless of engine used.

It really comes down to which has higher priority, max climb performance or minimal periodic maintenance and lowest possible cost.

P.S. I edited the title of your thread so it will be more descriptive for the search engine.

As usual, we talked about C/S versus F/P quite extensively yesterday, as three of us C/S pilots went to help an RV builder who was contemplating a fixed pitch on his 9A. It came down to this.............

We fly in a mountainous region. Our airports are at 4000'+ msl, and the mountains head quickly up to 11,000+ just a few miles away. For us, takeoff performance, and even descent performance, that you can get from a constant speed, means quite a bit. For those who live and fly closer to sea-level altitudes, it's not going to matter as much............I suppose..

L.Adamson --- RV6A

islandmonkey · #9 03-13-2010, 11:46 AM

Thanks Sam for editing the title. Thanks also to everyone else who replied.

I am interested in keeping things as light as possible. That was my main reason for asking. Going for fuel injection will have a slight weight penalty but that is more than compensated by the better fuel distribution between cylinders, therefore allowing lean of peak operation. I would love the flexibility of a VP prop but the weight penalty I feel will be to great. I am limited to 1175lbs max weight with no option to increase. So I will be aiming for an empty weight of around 765lbs. This will enable me to fly with full fuel and 50lbs of baggage. However to achieve this I must loose 20lbs but that is another story.

penguin · #10 03-13-2010, 02:53 PM

Anthony,

A Sensenich FP and an MT c/s weigh about the same for an O-320, when prop bolts, spacers, spinners as well as the prop, are taken into account (around 40lb). The lightest FP prop would be around 20lb installed. By using the lightest starter, a B&C SD-8 alternator, and a pair of P-mags you would be half way toward saving the other 20lb. So the c/s penalty is only 10lb.

Pete