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Sensenich Ground Adjustable Prop

Hi all...


I am the R&D/Design/Test Engineer here at Sensenich, maybe I can clear some things up.

The prop does look similiar to the Whirlwind although we use proprietary airfoils and is a different design.

As shown in the photo, we also have a pitch setting system so there is no need for protractors.

We co-cure our leading edges.

Although it is not required, we have also complied this prop to ASTM standards.


The Spinner Question...
We purchase our spinners from an aerospace manufacturer. It is an all hand laid carbon construction. There are galvanics where the spinner touches metal.



We have over 150 hours on our prototype prop and 200+ hours between our three test props out in the wild. The prototype prop is still in service and accumulating more hours.

If anyone has any questions, I would be more than happy to answer them.
 
a little history would be very informative

Thanks for jumping in Mike, it's great to 'talk' with the guys in the know.

- how long have you been running this type of airboat prop? I'm really impressed with this...if it can survive that kind of ****, it must be good!
- is the aircraft design appreciably different? How?
somebody is going to ask, so ....
- the aircraft version is double the cost of the airboat. How is this arrived at....I'm not surprised if it's liability insurance or something, just need to know.
 
flyboy1963 said:
Thanks for jumping in Mike, it's great to 'talk' with the guys in the know.

- how long have you been running this type of airboat prop? I'm really impressed with this...if it can survive that kind of ****, it must be good!
- is the aircraft design appreciably different? How?
somebody is going to ask, so ....
- the aircraft version is double the cost of the airboat. How is this arrived at....I'm not surprised if it's liability insurance or something, just need to know.
Click to expand...

We have had composite propellers since the early 90s.

Yes, the aircraft design is different, mainly in airfoil design. The construction steps are somewhat the same.

The increased aircraft propeller costs are mainly due to the amount of testing involved with developing the product.
 
weight

Mike,

I am very interested in the prop for my RV-4 but I am concerned about CG

I have a wood prop with a 12lb crush plate now. How can I add weight to the assembly to maintain my CG? I don't see a way to add weight other than a heavy spacer... is one available?

Sure would like to see some real performance numbers.

Chris M
 
Christopher Murphy said:
Mike,

I am very interested in the prop for my RV-4 but I am concerned about CG

I have a wood prop with a 12lb crush plate now. How can I add weight to the assembly to maintain my CG? I don't see a way to add weight other than a heavy spacer... is one available?

Sure would like to see some real performance numbers.

Chris M
Click to expand...

Our prop assembly is about 18 lbs without the spacer. Depending on what spacer you go with, you may be ok.
 
The sensenich GA prop is a good option, but there is an other prop that is the Whirl Wing Ground Adjustable that sell for around $2,500.00, plus spinner.

We will have it on display at Oshkosh in Building B2047/2048.

Bob-American Propeller
 
Initial Test Results

Some initial comparison numbers between the Sensenich metal prop and new composite prop.
*Composite prop + spinner + spacer is ~13 lbs lighter than equivalent metal prop combination.
*All speeds are true air speeds recorded on Dynon D100 which was within 1kt of the NTSP GPS 3 leg ground speed calibration @ 160 kts.

Test aircraft: RV-9A, 160 hp O-320-D2G 1393ft field elevation

70CM6S9-79 Static 2270 RPM
RPM limited 161 kts, 2600 RPM @ 8500ft density altitude
RPM limited 161 kts, 2600 RPM @ 10500ft density altitude
WOT 161 kts, 2620 RPM @11700ft density altitude

2G0M7/C72RG-0 (Gnd Adj Composite)
Pitch Pin #4 Static 2340 RPM
WOT 164 kts, 2727 RPM @ 8500 ft density altitude
WOT 164 kts, 2705 RPM @ 10500 ft density altitude

Pitch Pin #5 Static 2271 RPM
WOT 163 kts, 2660 RPM @ 8500 ft density altitude
WOT 161 kts, 2613 RPM @ 10500ft density altitude

Don't have any climb numbers yet and I will be trying the finer pitched #3 pin later.

Bill
 
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Mike,
I've got a new low-compression ECI OX-340S, that should develop ~160HP. Is the derated -340 a contender for this prop as well, or is it strictly limited to the -320 series?
 
Smokey Ray may be coming up this week to finally do the day of testing the different pitch options of the Sensenich as well as comparing it to the 2-blade Catto. Actual numbers aren't the goal as much as comparison numbers. Some have said that the pitch on our Catto isn't what they would recommend, but it is what Craig recommended for our 150hp setup, so we will see how it goes. I know we hoped for these numbers months ago, but we had other projects trump the -9A for a while. I am really enjoying it, though. Incredibly efficient!
 
KRviator said:
Mike,
I've got a new low-compression ECI OX-340S, that should develop ~160HP. Is the derated -340 a contender for this prop as well, or is it strictly limited to the -320 series?
Click to expand...
For anyone else interested, Sensenich reckons the new prop would suit the de-rated OX-340 "very well". :)

We shall soon see. I hope...
 
After flying my Aymar-Demuth extreme cruise pitched wood prop on an O-320-D1A up to Johnson Creek, Idaho and back home last week with my plane filled with camping equipment... I am now suddenly very interested in this prop. :eek:

My friend's O-320 equipped RV-4 with Sensenich 70CM series metal prop (I think pitched to at least 81", maybe even as much as 83... I'll have to ask him) flat outright blew my wings off on takeoff, climb, and even cruise speed performance up high in the the mountains. Now granted, his plane was loaded down somewhat lighter than mine, but the disparity in performance between these two RVs at the higher density altitudes was waaaaaaaay lots more than could be accounted for only by weight and the usual 4-vs-6 performance differences... even when we emptied out our camping gear and went on a day trip to another airstrip, my plane was still a dog compared to his. At lower altitudes, my top end cruise is just fine (just takes a long time to for me to build up to speed once leveled off, however) and then the two planes are pretty closely matched. Here in the flatlands of Texas the two planes are not all that far apart in climb or cruise.

I am now thoroughly convinced I need a different prop.

Of course, the "real fix" is to convert to CS but I simply haven't got the $10K budget to bankroll that. This new ground adjustable prop may be just what I need.

I have two big questions remaining about it however.

1) How many times /how frequently can you realistically adjust it, before you wear it out from disassembly/reassembly? In other words, is it made to withstand frequent repitching as a part of normal use and service, or it it designed only to try a few different pitches when first installed in order to find the best comprise pitch and then you must lock it down and leave it there for the duration? If, say for instance, I make even as much as 2 or 3 trips from Texas to the mountains and back, will re-pitching it back and forth along the way up there and back at my fuel stops be an "abusive" frequency?

2) The galvanics issues between the carbon fiber and metal contact... what measures can be taken to mitigate this from becoming a real problem? I would assume that as long as you keep any water out of the contact areas, that galvanic corrosion will be kept to a minimum. Would coating these contact areas with something like a thin layer of EZTurn/FuelLube grease be of any benefit since that would pretty much seal out any water, and it's thick enough that it's not all going to get too easily slung out by centrifugal force, and it's got a high enough melting point that it's not all going to get melted out by heat either. Thoughts?
 
I would talk to Sensenich about that. I don't think it has a limited number of pitch changes before needing to replace parts. You may want to replace bolts after repitching X number of times. Other than that, I don't think it would matter. If I were going on a trip like you describe, I would repitch it before leaving home and after returning home, and not en route. Too many opportunities to miss something. I would test fly after every pitch change in a controlled format.
 
not an issue

Neither question is an issue. My prop has no carbon contacting aluminium so the is no galvanic potential created in the presence of moisture. Keep in mind only the spar is carbon. The rest is fiberglass. The spinner is carbon but it has a glass isolation ply over the carbon to prevent any corrosion from forming.

After getting a good look at the hub, there should be no issue to clamping up the blade. The fit is as perfect as I can tell between blade and hub and does not apear to point load the blade anywhere.
 
On the Sensenich prop, the whole blade is carbon fiber, not just the spar. It may have a coating over Otto prevent the corrosion mentioned, but the whole blade is carbon fiber.
 
BJohnson said:
The spinner is carbon but it has a glass isolation ply over the carbon to prevent any corrosion from forming.
Click to expand...

How about the carbon fiber bulkheads? Do they also have a fiberglass isolation layer over the carbon to prevent corrosion where they contact the prop hub? I could not really tell from the photos you posted earlier. The one bulkhead photo only shows the rear side of the aft bulkhead and it looks kinda like there is no glass layer where it would contact the crankshaft or prop spacer.

This is my primary concern here. Back when I owned my Cherokee 140, I got a service advisory letter from the maker of my aftermarket composite spinner about corrosion problems with their carbon fiber spinner bulkheads they sold for PA28 models. The letter included photos showing corrosion pitting on the front and back of a Sensenich aluminum prop that ate pretty deep into the metal where it had contacted the bulkheads. Luckily, I had good old fashioned aluminum bulkheads and this company's earlier model of plain fiberglass spinner so I didn't face the corrosion problem on my Cherokee.

BTW, the bulkhead photo posted earlier looks an awful lot exactly like the same construction style as the company who made the aftermarket composite spinner components for my old Cherokee. SensenichMike said their spinner were outsourced... I wonder if it is the same spinner company?
 
Well, I guess I'll be another one reporting on this prop in about a week or so... Thanks to a new crack being discovered in my wood Aymar-Demuth prop, I am going to have to change props a little earlier than expected :-/

My new Sensenich ground adjustable prop is supposed to be here by Friday. Hopefully I'll get it installed, best pitch dialed in, and my 5 hours of phase 1 flown off by Thurs/Friday of next week so I might still be able to make it to Oshkosh for closing weekend.
 
Neal@F14 said:
Well, I guess I'll be another one reporting on this prop in about a week or so... Thanks to a new crack being discovered in my wood Aymar-Demuth prop, I am going to have to change props a little earlier than expected :-/

My new Sensenich ground adjustable prop is supposed to be here by Friday. Hopefully I'll get it installed, best pitch dialed in, and my 5 hours of phase 1 flown off by Thurs/Friday of next week so I might still be able to make it to Oshkosh for closing weekend.
Click to expand...

I look forward to your PIREP, particularly your opinion of how convenient the pitch change adjustment is.
 
My new Sensenich ground adjustable prop just arrived. It looks pretty much exactly like the photos Brice Johnson posted earlier, except mine is white with red tips. When I called Sensenich on Monday morning they did not have any white ones in stock and normally would be about two weeks out from being able to ship, but pulled a set of blades from the production line and had them painted/tested/balanced in a rush order especially for me and shipped everything overnight so that I'd have the new prop and spinner by this weekend and still have a chance to make it to Oshkosh this year.

Now that level of customer service on a new customer order out of the blue is nothing short of phenomenal and my hat's off to Donald Rowell, Cindy Keene, and the rest of the folks at Sensenich who pulled this together to get me a new prop, in the colors I wanted, into my hands before the work week was out! :cool: :D :) ;)


I'll get it installed tomorrow and will take photos and prepare an installation and flight testing/performance report thread as soon as I can.
 
We got the Sensenich GA prop in the 68" diameter configuration for Marilyn's 160 HP RV-4. It's a 1987 completion, short gear leg RV-4 with old style wheel pants and sheet metal intersect fairings. She's been flying it with this prop for a couple of months now, which being winter in the Great Northwet, hasn't been too many flights.
Marilyn is not a speed or performance nut like some of us guys, and never flys at full throttle except for take off.
I haven't flown it with the new prop yet, I work on the RV-8 while she flies.
She is TOTALLY JAZZED by this prop.
She reports very good subjective performance, smoother than the Metal Sensi, or the wood Hendrickson on the T-18, and KILLER looks.
Sorry, she's not going to do GPS runs at full throttle or anything.
However she did report an indicated airspeed of 175 MPH part throttle @ 2600RPM flying at 2000' altitude, also it has great sustained climb rate to 6500' were she met the class B airspace floor. None of this is remarkable, considering it's winter and the outside air temp is near freezing, but she loves it, I had a good time installing it, with absolutely no problems even though it also got a new Saber extension & bolts. Everything fit first try and it tracks perfectly.
So I'm reporting satisfaction as a seat of the pants comparison for performance, but the fit, finish, communication etc all get top marks.
PS; my link has 3 pic of the prop.
 
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wt and balance

can you talk about the weight of the prop and extension you took off compared to the weight of the new prop and extension.

I am interested in the prop but concerned that it is too light for the RV-4.

Chris M
 
Chris;
the prop weight is 18 pounds and the Saber extension 4 pounds.
The fixed pitch Sensenich was more...I forget how much. So: more than a wood prop, less than an aluminum prop.
The Weight of Marilyn's plane was less (of course) and the moment moved aft some, but not bad. Before, the back seater could weigh 215 lbs. now less, I would have to recheck, but it's more than 180 pounds IIRC.
Now Marilyn cannot exceed the forward CG in any configuration, but can load the plane in such a way that she is on the Fwd CG with nothing in the rear seat or baggage.
Lots of RV-4s fly every day with lighter wood props.
 
wt/bal

Thanks Scott,

I had one of the first Sensi metal props on my airplane(rv-4) for about 400 hours and it was a good all around performer and kept my cg at the fwd limit without a pax

I replaced it with a Catto prop to eliminate the rpm restriction to get full power for racing. I have Sabre's 12 lb crush plate and a 6 lbs extention which ( if I remember correctly ) makes the catto set up 7 lbs lighter than the metal prop.


I know how my airplane flys with this "lighter" catto prop and I don't want to go any lighter up front.

I think the carbon fiber prop would be too light and I don't have a dampner or wish to install one. I think if I could get a steel extention I would give it a try.

Thanks for the info.

just a note;

a know a guy who ran the metal prop at 2700rpm or more and it was very fast...faster than my catto

Chris M
 
G'day Jim, It isn't a -360, but I have one installed on my 165HP O-340-powered -9A and it works well. I have it set up using pitch pin 4 and see about 2750RPM at 8000', so will probably move up to pin 5 when I think of it. Climb rate is around 1800FPM at 1320Lbs.
 
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