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Ground adjustable prop vs C/S

bizpilot

Member
Hi all, pre planning to build a RV7A, wondering what pros and cons are between ground adjustable and constant speed propellers?
 
Considerable cost difference. A constant speed speaks for itself, a ground adjustable will allow you to "tune" the prop to suit your mission profile and after some experimation will find the pitch that gives you the best compromise. In the end you will still have a fixed pitch propeller. It is NOT something that you will routinley adjust prior any given flight, they can also be finnickey in getting blade angles adjusted just right. I think the 320/360 series Lyc's are better suited for a pure fixed pitch or C/S props, however Sensenich does have a G/A prop specifically designed for the RV series ($3500), I am curious if anybody has any pireps on that installation.
 
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"I think the 320/360 series Lyc's are better suited for a pure fixed pitch or C/S props, however Sensenich does have a G/A prop specifically designed for the RV series ($3500), I am curious if anybody has any pireps on that installation."

My next door hangar neighbor has the Sensi ground adjustable prop on his RV9A and seems quite pleased with it. His previous aircraft had a constant speed prop and I don't think he misses the cost, weight and complexity of the C/S prop. I've watched him adjust the Sensi. While not easy, it's also not difficult. By contrast, my Warp Drive is considerably more difficult to adjust as it is infinitely adjustable through its range, rather than using the stop-block technique employed by Sensi.

Oh, the Sensi ground adjustable prop also looks pretty spiffy on his RV9A.
 
CG is also a consideration in this choice. The Sensi GA is around 12 lbs, same as my 3 blade Catto, but I also have a 20 lb crush plate on the nose to help keep CG in range, which it does. Without the crush plate, your baggage compartment weight will be limited and I don't see how you could install a plate with the GA prop.
 
C/S VS. G/A VS. Sensenich or Catto dilemma

I was kind of in the same dilemma. I wanted to get away from the cost/weight/complexity of a C/S for my new -7 build and I really liked the looks and adjustability of the Sensenich G/A prop....but I eventually decided to go with the Catto three blade with nickel leading edges. My project is still under construction so I haven?t flown the new prop yet, but I have full confidence that it?ll perform as advertised. I actually have a Catto three blade on my -4 and I absolutely love it!!

Mark
 
Ground Adj. Prop Option

Besides the Sensenich GA prop, there is also available the Whirlwind GA200-72 designed for RV airplanes with special attention to top end speed and cruise performance. Weight is 18 lbs. and can be used on Lycoming style 320/360 engines, with cost of 1/3 of what a typical constant prop goes for.
 
C/S prop, hands down

Going with a constant speed prop was one of, if not the, best building decisions I made and I almost didn't do it. Yeah, it hurts the pocketbook up front. But, I think you'll actually come out ahead in the long run fuel savings.

I've talked about more of the reasons to go with a C/S in other threads. But, I think putting a fixed pitch on an RV is like buying a Corvette and only driving it in 2nd gear. C/S really opens up the performance envelope and gives you a lot more flexibility.
 
Don?t underestimate the value of a light aircraft. An RV loaded to gross weight is an albatross compared to a sub 1000lb aircraft with minimal fuel load on board. Fighter jet versus 18wheeler.
 
orig on my 320 rv6 I had a sensenich cruise prop but I wanted more takeoff performance,went to a catto 3 blade which worked out ok and looked good,downfall was harder to remove cowling and I am in a shared hanger w a high wing next to me whose wing was to close for comfort to my prop,next came a whirlwind ga which turned out pretty good ,easy to dial in ,good looking and smooth,but if my engine had setup for constance speed that's the way to go if you have the xtra money
 
Going with a constant speed prop was one of, if not the, best building decisions I made and I almost didn't do it. Yeah, it hurts the pocketbook up front. But, I think you'll actually come out ahead in the long run fuel savings.

I've talked about more of the reasons to go with a C/S in other threads. But, I think putting a fixed pitch on an RV is like buying a Corvette and only driving it in 2nd gear. C/S really opens up the performance envelope and gives you a lot more flexibility.

If maintained I.A.W. the manufacturer, it will be the most expensive (per hour) single item on your aircraft to maintain.

And IF you get metal in your oil, it will be in your prop also................:eek:
 
Don?t underestimate the value of a light aircraft. An RV loaded to gross weight is an albatross compared to a sub 1000lb aircraft with minimal fuel load on board. Fighter jet versus 18wheeler.

Soooo true... My 6A is light, and when I am low on fuel (local flight) the plane is a real joy to fly. The lighter it gets, the more fun it is. 320 Sen metal fp.

A typical flight my manual trim knob does not need to be moved more than 1/4 inch for take off, cruse and landing. And many flights, not touched at all. No adjustment needed during flap extension.
 
I own a D95A travel Air,(IO-360 B1B?s) and 1/2 a RV14A IO 390. The props on the Travel Air ( new 3 years ago) don?t have a AD for overhaul at every 500 hours any more, but still have a RPM restriction of no continuous operation between 2050 and 2350. We have no such restriction on the Hartzell C/S 2 blade on the 14A.
My question is, is this RPM range possibly a restriction on any RV 4cylinder with a Hartzell?
 
Given the very good climb rates of RV's , even with a fixed-pitch cruise prop, I'm not sure what the advantage of a ground adjustable prop is. A constant-speed prop would be great for maximum versatility, sure, but I don't see a practical day-to-day value in having a ground-adjustable prop.

The only scenario I could think of is if you just occasionally fly out of very short and very high density altitude strips. Then you might wish you could manually adjust the prop before that one takeoff. I'm skeptical of how often one would even need or want to do that though.
 
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Maybe the f/p maker hits exactly what you want; maybe not. A good gnd adj can let you hit your desired 'sweet spot' for your a/c.
 
Advantage

Given the very good climb rates of RV's , even with a fixed-pitch cruise prop, I'm not sure what the advantage of a ground adjustable prop is. A constant-speed prop would be great for maximum versatility, sure, but I don't see a practical day-to-day value in having a ground-adjustable prop.

The only scenario I could think of is if you just occasionally fly out of very short and very high density altitude strips. Then you might wish you could manually adjust the prop before that one takeoff. I'm skeptical of how often one would even need or want to do that though.


The advantage is you can adjust the pitch to the best setting for your aircrafts weight , speed, operating conditions where as when you buy that catto it is what it is for the most part. You can get a larger heavier prop extention to help with CG. I really like my Sensi GA
Cm
 
The main advantage of the CS is the ability to set low pitch for takeoff and climb, then set it for efficient cruise once at altitude. When I built my RV9 I considered the CS but chose the Sensi GA because the RV9 has such a short ground roll and climb is 1500 to 2000 fpm (even with the GA set at High Pitch) there is no need for the CS adjustments.

I flew with a CS for many years in both singles and twins and wouldn't trade my GA for a CS, even if it was paid for by someone else. In fact, cost never factored into it. Performance was the deciding factor for me.

I challenge anyone considering a CS and not flown behind a GA (set for optimum cruise), to do so before they make a choice between the two.

Steve
 
I own a D95A travel Air,(IO-360 B1B?s) and 1/2 a RV14A IO 390. The props on the Travel Air ( new 3 years ago) don?t have a AD for overhaul at every 500 hours any more, but still have a RPM restriction of no continuous operation between 2050 and 2350. We have no such restriction on the Hartzell C/S 2 blade on the 14A.

My question is, is this RPM range possibly a restriction on any RV 4cylinder with a Hartzell?

Restrictions are based on engine/prop combination (not airframe) and are specified by the prop manufacturer, if specified at all.

By that rule, some RVs have restrictions and some do not. Simply because the engine/prop combinations chosen by the individual builders can be different.

As example, the stock YIO-360-M1B and Hartzell BA pair sold by Vans for the RV7 does not have rpm restriction.

However, if one chose to install an IO-360-A1A and McCauley from an old Mooney, that pairs restriction would remain in effect.
 
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