Prop considerations for fp 9a?

[Lionclaw]

I had planned on getting a Sensenich for my fp 9a, but the 2600 rpm red line kinda bothers me. I'll be using a 160hp O-320.

Does anyone have problems keeping rpm below 2600? Do you have to babysit the throttle to keep it from going over?

Alternatively, I've been giving the 2-blade Catto some thought. Does it require the wood fp spinner kit? Will I have to do regular retorques on the Catto?

An info/advice is greatly appreciated!

[gasman]

I have a 0320 with that same prop on my 6a. The 100 rpm restriction is not a problem. What really is a problem is to make sure that your tach reads right. Purchase a prop check from Spruce or a hobby shop. About $45.00 or so. It reads the strobe of the prop and is right on. To check the unit, point it at a light in your house, it will read 3600 rpm. That is 60 cycle ac per second. So 60 cycles in 60 seconds will be 60X60=3600.

Getting back to the prop. The main time that you will need to watch the rpm is when you are doing a speed run down low. The plane won't blast past 2600 but as you come up to 2600, you will need to cut back from going over.

The prop works great, and is trouble free. Sure wish it didn't have that restriction though.

[Mel]

Originally Posted by gasman

To check the unit, point it at a light in your house, it will read 3600 rpm. That is 60 cycle ac per second. So 60 cycles in 60 seconds will be 60X60=3600.

This works only on fluorescent lights. Incandescent light bulbs glow constantly.

[pierre smith]

.....with an RPM limit of over 3000 revs. I flew Brian's -4 yesterday with his brand new 2 bladed Catto which is designed for max cruise speed and I managed 2710 RPM doing 189 MPH at 2000'. Craig asked him if he minded turning it 2750 at 7500 to which Brian said no. We haven't had it to 7500 yet but we will shortly.
[IMG][/IMG]

Craig painted it to match the RV's colors and it's a work of art and incredibly smooth as well. I have a three blade on my -6A and am very happy three years and 430 hours later.

Regards,

[BillC]

Andy,
I have the Sensenich and 160Hp O320 combination and the only time I came close to redline (2600rpm) was when doing speed runs at 8000 ft and last week when I got to do a high speed pass (192mph TAS) over the field @1450ft msl. Normally I fly at between 55% and 65% which puts it at ~2350-2450 RPM. This range gives me a good 150 to 165 mph TAS with fuel burn ~7 to 7.8 GPH. The reduction of 100 rpm means that you loose ~5 hp but that's only if your after more speed WOT. With fuel prices 55%-65% makes more sense and your still going considerably faster than most. That is accept for the 180hp-200hp RVs. I,m sure either prop will give great performance. (Remember that a certified engine and the Sensenich prop combination will only require 25 Hrs phase-1). Of course YMMV.

[carguy614]

Can't say I've been unhappy with my Sensenich. At altitude and at 2590 I get 192 MPH. You can just barely overspeed it with a low altitude speed run. Smooth and quiet, and balanced and tracked perfect. It really is a great match for the plane. Can't really see myself pushing the aircraft past those numbers anyway. Climb performance is great, and I am getting great fuel burns at low MP and RPM when I am just buzzing around the beach. That being said, I have flown Pierre's plane with his 3 blade Catto. It is a very smooth combination on his 6, and there is nothing slow about his ship either. Consider your weight and balance needs before making your selection. The concensus is, Both the Sensenich and Catto seem to be well matched good performing props. Seems like they are the 2 that come to the top when considering how to prop these planes, and for good reason.

Regards, Chris

[gasman]

Originally Posted by Mel

This works only on fluorescent lights. Incandescent light bulbs glow constantly.

Only to the human eye.......... Try it, it will read the cycles of an incandescent light bulb. It won't work on a headlight........... it is DC.

[tc1234c]

The Sensenich propeller from Van's is a standard propeller (70CM()S9-0-79). You can also order either a climb propeller (-78) or a cruise propeller (-81) directly from Sensenich. I have the standard propeller. It usually does not turn faster than 2,600 rpm at leveled flight. When you descend, you do have to pull the power back. We do that anyway. Over speed is not a major concern. However, the maximum rated power for O-320 is at 2,700 rpm. If you want to squeeze every bit of the power out of the engine, you need to get something else.

http://www.sensenich.com/direct/vans.htm

[fliier]

The prop limitation does give you an upper airspeed limit well below Vne in certain circumstances, for example where you are in loose formation and the other aircraft start descending at a higher speed than you can follow.

That really is only a minor issue, and is more than offset by that really cool aluminum spinner than you can have polished to a mirror finish!


John Allen
RV-6A

[RVbySDI]

Originally Posted by gasman

Only to the human eye.......... Try it, it will read the cycles of an incandescent light bulb. It won't work on a headlight........... it is DC.

I would agree with this. The human eye in most instances is unable to see the "flicker" cycle of a 60 Hz AC current.

I do know that most people do not even notice the 60 Hz cycle but I do have problems looking at a computer monitor set at refresh rates of 60 Hz. It gives me a headache. I usually will set my monitors to 72 or 75 Hz. This seems to work well for me. Otherwise I can develop a quick headache if I stare at a computer monitor set at 60 Hz for very long.

Sorry for hijacking the thread but the previous comments brought up an issue I always have to deal with as a network administrator.