Anyone running a Sensenich GA prop on their Patrol?

[Viking]

I’m getting ready to pull the trigger on a patrol QB kit, and I am trying to put the cart as far ahead of the horse as possible. Anyone here running the Sensenich ground adjustable stol prop on their patrol? I’ll have an O-360 spinning it.

[Mark Goldberg]

Mr. Viking - I tried the Sensenich GA on my LSA. If you would like to ask about it m y cell is 512/626-7886. Mark

[Battson]

The Patrol is as flexible as the 4-place, a high performing aircraft. I have enjoyed flying the Patrol and comparing with the 4-place.

Putting a fixed pitch prop on a Patrol is selling your future airplane a long way short, in my opinion. Plus it could be bad for engine longevity, unless you select a cruise prop. Of course, that cruise prop would hurt the STOL performance. The speed range is much too large in a Patrol for fixed pitch, in my opinion.

[500AGL]

The current ground adjustable Sensenich is excellent in all respects. But as stated above, have a clear and decisive mission for it because a CS will make the Patrol a different animal.

[Bcone1381]

I'd like to see a Patrol with a GA Whirlwind or Sensenich. It would be simple to build, simple and inexpensive to maintain and make it light. Set it up for STOL then adjust it for cruise after the event.

Builders have budgets, and I thought a different view might be worthwhile without being argumentative or difficult. Several years ago I asked what the performance change would be with a C/S over a Fixed pitch (not G/A) and I think Bob thought 10-15 mph. Does that sound about right?

[Viking]

Hey Brooks, I completely agree. I don't know exactly how much of a sacrifice a GA prop would be over a CS, but I think if you had it pitched for the mission at hand, it could be a very workable tradeoff. these new GA props are supposedly very easy and quick to adjust, lighter than anything but a fixed wood prop, and the simplicity and low cost is hard to ignore. My home airport is 5500ft paved, and only 840' MSL. I see myself pitching for cruise on a long cross country, and then making an adjustment when I get there and am ready to go play. I could be totally wrong here, but I feel like my nose being 20-30lb lighter than a CS prop, and my gas budget being 7-12k fatter is a good starting point.

[JimParker256]

True "fixed pitch" props can be highly optimized for one thing, at the expense of the other thing... A well-optimized F/P cruise prop could well be faster than a C/S prop because it would be totally optimized for cruise performance, and it would be lighter than a C/S prop, which in turn requires the wings to produce less lift, thereby reducing induced drag. But such a prop would definitely be underwhelming in the climb department compared to the C/S prop. (I had a Grumman Traveler that would cruise at 132 KTAS, but best climb was around 650 fpm...) Likewise, a fully-optimized F/P climb prop would likely outclimb a C/S prop. Again, lower weight and fully optimized airfoil shape for climbing... But that prop would be S-L-O-W in cruise, for sure. (Look at the Super Cubs with Borer props...) Flying around with the "other" F/P prop in the plane so you could switch them out for backcountry flying once you got there is "possible" with a Bearhawk, but somewhat of a PITA. (Not to mention the cost of going through multiple props to find your two "ideal" props...)

A ground adjustable F/P prop allows you to use a single prop, and optimize its pitch for either cruise or climb – just not both at the same time. It's going to be heavier than a true F/P prop, but lighter than the C/S prop and governor. Thus the theoretical performance envelope would be somewhere between the F/P and C/S props on both ends of the spectrum: Slightly lower climb and cruise than the "swapped-out" F/P props, slightly better climb and cruise than the C/S... But that's the theoretical world...

In the real world, few people will weed through an entire collection of fixed-pitch props to find the two "optimal" props for climb and cruise. Fewer still will haul a climb prop as baggage when they fly cross-country for some backcountry flying. Swapping props is not difficult, but it is time consuming, and re-torquing after a few hours is something you don't want to skip – especially with a wood prop.

Likewise, just adjusting the pitch for the G/A props is enough of a PITA that most of us will seek out a compromise pitch that gives us whatever we define as a reasonable tradeoff between climb and cruise performance, then leave it at that setting 99% of the time.

Case in point: My RANS S-6 Coyote has a Rotax 912 ULS 100 HP engine and a Warp Drive 3-blade, ground-adjustable prop. Optimized for climb, the airplane climbs at upwards of 1200 FPM, but cruises at about 100 mph TAS. Set up for best cruise performance, it climbs at about 750 FPM, and cruises at ~115 mph TAS. I'm in the process of adjusting my prop to split the difference (~1000 FPM, and ~110 mph cruise). Waiting for decent weather to test out my latest tweak...

But, given the choice of G/A or C/S, I would opt for C/S every time. It is SO much easier to select the RPM you want, and have the governor maintain it for you! Not an option for my E-LSA airplane (it would invalidate the airworthiness certificate), unless they change the Light Sport rules in the future. If that happens, I'll had a C/S prop on there in a heartbeat! Meantime, I'm reasonably content with the inexpensive ground adjustable Warp Drive prop.

[zkelley2]

The added weight of a composite CS prop is pretty marginal these days. My carbon CS is the same weight as an aluminum fixed pitch. Ya, you can save more weight with the composite fixed.

But, the 10-15% more horsepower available for takeoff/climb with the constant speed is a wild performance increase that is worth the minimal to no added weight. A constant speed prop will give more takeoff performance than anything you can add to your engine short of nitrous. 10:1 pistons only give you about 5.5%. Even with a climb or "borer" prop, you're not spinning max rpm on takeoff. Just closer to it.

An o-360 at WOT at sea level and 2400rpm, which is towards or at the climb prop range is only making ~164hp, 170hp at 2500rpm. I think the borer prop STC for the cub shows a static around 2475rpm. In a mix prop situation you're probably looking at 2300ish static, 160HP. So, It would be more efficient and similar HP available to throw a 160hp o-320 on there and go constant speed, and you'd still end up a lot faster in cruise.

[WyoDave]

I appreciate the OP's question. And agree with all of the comments. Including that MOST GA props are a PITA to adjust (I have one on an S7S). Also the comment that many builders budget doesn't allow a composite CS prop. One big advantage I have heard from reviews of the Sensenich GA is that you can literally adjust it in 5 minutes without even taking the spinner off. To me, that makes it much more viable for a plane that will be used for local low & slow with the occasional cross country mixed in.

[JimParker256]

WyoDave, I've read the same about the Sensenich G/A props, and would love to have one. They appear use a "pin" system to set the blade pitch, so it is WAY easier to get all three blades to the pitch you want, and all the same every time. It took me three tries to get my Warp Drive 3-blade to the exact pitch I wanted, and even then, one blade is 0.05º off pitch...

But given the fact that I've already have a perfectly good (well, not perfect, but certainly good enough) Warp Drive prop, it's pretty hard to justify spending the money right now to get a new Sensenich – they're not exactly giving them away... (I could purchase 3 new Warp Drive props for what Sensenich charges for one.) That said, if Santa were to bring one for Christmas, I'd install it in a heartbeat, and be one happy pilot! LOL

But back to the point ZKelly made: A composite C/S prop might be more expensive (and harder to find on the used market for the bargain hunters), but the lighter weight does have a large impact. I owned a turbo-normalized Commander 114 for a while. The turbo system added a lot of weight up front, bringing the CG far enough forward that I had to carry ballast in the baggage area any time I flew. Replacing the aluminum McCauley prop with an MT composite prop gained back about 2/3 the weight gained with the turbo, and the W&B problems were pretty much gone. Additional bonus, blade design improvements meant that the Commander both climbed and cruised measurably faster than with the 1970s vintage McCauley.

And to Viking (the OP): The entire Bearhawk product line has such a wide operating speed range that no fixed-pitch prop can accommodate it with any real degree of efficiency. Other than an LSA model that needs to comply with Light Sport rules, it seems "wrong" to restrict the airplane's capabilities by installing a fixed-pitch prop. If the cost of a new one is prohibitive (and Mark G can help you with that, having negotiated a decent discount with a few of the prop vendors) I personally would scour Barnstormers, Trade-a-Plane, and everywhere else I could think of for a good used C/S prop – including an aluminum one – rather than settling for a fixed pitch or ground-adjustable prop. Spending that much time, effort, and money to build the single most flexible experimental aircraft on the market, then giving up a good bit of that flexibility just doesn't make any sense to me!

[gregc]

I'll be a little bit of a contrarian here and note that while a C/S prop is 'better', as we all know everthing in aviation entails trade-offs. A C/S prop is always more expensive, more complicated and usually heavier. Your mission and environment matter as well. I am going to start with a fixed pitch composite on my Companion and still expect to have better performance than most, if not all, of the certified aircraft at my field. I am also flying mostly near sea level and not routinely making 1000 mile cross country flights so for me it is not really 'wrong' (an apology beforehand to Jim since I realize that by 'wrong' he means something closer to seriously suboptimal ).

[Utah-Jay]

Why is no one talking about the in electric in-flight adjustable prop that has 3 setting? It is adjustable via a blue knob/dial
1) Takeoff
2) Climb
3 Cruise

[zkelley2]

Why is no one talking about the in electric in-flight adjustable prop that has 3 setting? It is adjustable via a blue knob/dial
1) Takeoff
2) Climb
3 Cruise

Because I don't think airmaster makes one for an O-360 and the electric MT is just as expensive as the hydraulic.



On price, if you have a McCaulley hub, Whirlwind will put their blades in it. A lot cheaper than buying an MT or Hartzel composite.

[Viking]

Thanks for all the replies everyone!! As several of you have pointed out, a prop (as with everything in an airplane) is a trade off. I am really interested in the sensenich GA stol prop for some of the benefits that it might possibly give me. Obviously the C/S is going to be the best overall performance across a wide range, but it adds significant weight and additional points of failure to the aircraft. The new hartzell composite units are really slick, but they still can’t match the sub 20lb of the ground adjustable prop.

there is also the issue of cost. I can afford the Hartzell trailblazer, and could even better afford a lesser constant speed prop, but any way you slice it, with governor that setup will be 7-10k more than a $3500 G/A prop. That’s a lot of gas.

I wouldn’t consider flying around with two props, and I probably wouldn’t even consider the g/a prop if it were as much effort as older g/a props to adjust. The Sensenich system really has me intrigued though. People report that it takes longer to remove the spinner than to readjust the prop. I have that kind of time. Realistically, Assuming the prop will do it, I see myself having 3 different pitch settings. High static rpm stol, general middle ground decent performance, and fast cruise. I would be able to make the adjustments for the upcoming flight, and then readjust later as needed.

All in all, I think I will probably give this prop a try. I have to actually get a kit first anyway, so it’s not going to happen this week or anything. My goal is to build a light, simple patrol, and I feel like some of these trade offs are pointing me in this direction. Sensenich has these props STCd for the PA18 now, and reports from the field say that they are really nice. I guess Nobody has first hand experience on a patrol yet, so I’ll be a guinea pig. Worst case, I’ll sell it and buy a C/S prop.

[JimParker256]

I believe Mark G (way earlier in the responses) indicated that he DOES have some experience with the Sensenich G/A prop, and suggested you give him a call if you want his feedback... I would take him up on that.

[Viking]

Hey Jim, Thanks for your replies!! I did take Mark G up on his offer of information, but unfortunately, his experience with a Sensenich GA prop was with his LSA, and it turned out to be a different prop than the current STOL offering from Sensenich.

[Battson]

Like everything in aviation, it's a trade off. You can certainly find a middle of the range pitch which will allow the engine to operate normally, as long as you don't mind a heavier tail and less than phenomenal performance.

Just seeing as it wasn't clarified, if you set up for best STOL performance then you may see something like 18 or 17"Hg MAP in level flight, in order to manage RPM from the engine down to acceptable levels i.e. 2400 RPM or 2500 RPM. Hard to know until someone builds it. I think there are several Patrol's with fixed pitch props already, if you can look those people up then you might be able to get some first hand information.