Sensenich ground adjustable prop

faa_signed.png

Here is a screenshot of that section. I just don't want to post my and my mechanics information publicly on the internet. Private Message me your email address and I'll send over the PDF or reach out to Steve; he has the PDF as well.
 
sophistical said:
View attachment 21358

Here is a screenshot of that section. I just don't want to post my and my mechanics information publicly on the internet. Private Message me your email address and I'll send over the PDF or reach out to Steve; he has the PDF as well.
Click to expand...

It’s public info anyhow, anybody can spend $10 and get the CD with all the 337s including this one. Thanks for sending it. Wanted to see if it was an ASI or a DAR that did the field approval.


Sent from my iPad using Tapatalk
 
I’m looking to put the Sens on my 22/20 and hope to improve take off performance, yet have the option to run coarse switched over to my “little” 8.50s and maximize cruise for x-country missions in the winter.

What say ye all to having it cut down to 80”? will it help with top-end without losing too much on the stol end when pitched fine?
 
Armstrong said:
I’m looking to put the Sens on my 22/20 and hope to improve take off performance, yet have the option to run coarse switched over to my “little” 8.50s and maximize cruise for x-country missions in the winter.

What say ye all to having it cut down to 80”? will it help with top-end without losing too much on the stol end when pitched fine?
Click to expand...

I’ve been wondering the same thing. You can go down to 78” on the STOL propeller.

I can do 130mph TAS cruise with 8.50s and a 56 pitch M74. I would like to keep the speed and improve take off with the GA prop in the center pitch, then have the option to improve T/O or cruise speed with pitch adjustment.

It will probably take a call to Sensenich, with current aircraft specifics, to get some advise on the best combo of prop length for the desired PA22/20 performance. Given the improved blade design, light weight and adjustability I think my goals are possible.
 
Thanks, yes, I’ve been back and forth with Sensenich a bit, but I might have over done it with the questions! We’ll see, it’s been a couple weeks since I’d left it with them.

Any other insights would be great.
 
Armstrong said:
Thanks, yes, I’ve been back and forth with Sensenich a bit, but I might have over done it with the questions! We’ll see, it’s been a couple weeks since I’d left it with them.

Any other insights would be great.
Click to expand...

Can you share a summary of what Sensenich has told you so far?
 
Just heard back from Don Rowell at Sensenich.

No hard data of course (I wouldn’t expect it) but Don says shortening the prop will (in coarse pitch setting) decrease cruise by a bit, and also reduce rate of climb and takeoff performance somewhat as compared to the standard 82” length at the same pitch.

The tips (not the root end) are cut down when they come out of the mold. So I take from this, that those tips in the 82” length are optimal, and perhaps the only reason we would want to shorten them would be for ground clearance issues. I’ve got the extended gear so my order will be the 82”.

At 2700 rpm redline, those tips will be about 87% of mach. I guess what little understanding I had about propeller tip speeds, and the efficiency lost as they approach the speed of sound with old conventional props, goes out the window with these high-tech profiles.

I’m getting closer to my decision!
 
Armstrong said:
Just heard back from Don Rowell at Sensenich.

No hard data of course (I wouldn’t expect it) but Don says shortening the prop will (in coarse pitch setting) decrease cruise by a bit, and also reduce rate of climb and takeoff performance somewhat as compared to the standard 82” length at the same pitch.

The tips (not the root end) are cut down when they come out of the mold. So I take from this, that those tips in the 82” length are optimal, and perhaps the only reason we would want to shorten them would be for ground clearance issues. I’ve got the extended gear so my order will be the 82”.

At 2700 rpm redline, those tips will be about 87% of mach. I guess what little understanding I had about propeller tip speeds, and the efficiency lost as they approach the speed of sound with old conventional props, goes out the window with these high-tech profiles.

I’m getting closer to my decision!
Click to expand...

Really interesting info! Makes me wonder if the Mid Speed GA prop at 76” would be a better all around choice for what I want to achieve.

I did not expect the reduction from 82” to 80” to have a speed penalty. I thought it would allow a faster cruise.
 
I did the flight testing on the Sensenich ground adjustable prop for the 150/160 hp Super Cub. We initially tested a 76" and an 82" version until the FAA test pilot tore up the 76" prop which is when I started doing the flying and we only finished testing the 82". I am also a Sensenich dealer and sent an 82" prop to a fellow Pacer owner. He did not get any more speed, he actually lost speed. I will get him to post his experience here.

I have been running the prop on my Super Cub for a almost 2 years, I got a field approval before the STC was finished. Prior to the Sensenich ground adjustable prop I was running an 82" Borer McCauley 1A175 pitched for best climb at 41". On my SC the Sensenich GA prop pitched with pin #3 (0-5) to get me off the ground quicker and cruise 5-6 mph faster opposed to my Borer prop. It also took 15 lbs off the nose and the prop spins up way faster and acts as a speed brake when I pull the power back which are all great features in the way I operate my Super Cub for STOL ops on gravel bars in the Brazos River. The stainless leading edge is a nice benefit as well since they are harder than aluminum and wear better when operating in sand and gravel. I can pick up almost 10 mph in the highest pitch but it does burn way more gas and I have to watch my CHTs in the climb.
PXL_20230910_132646087.jpg
 
Thanks Steve, I think that prop is as good as it gets for an SC. On my Pacer I’m OK losing speed from a stock configuration for the benefit of STOL performance, it’s just what it’s going to deliver in the coarse setting for higher cruise I’m concerned with.

Since I really only plan on adjusting pitch for summer and winter, maybe it makes more sense to find a used Borer for the summer, and use my 74DM for winter.
 
Subsonic said:
That is amazing! What is your "cruise" power setting? 75%?
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“Cruise” is pretty much firewalled. Depending on altitude sometimes the throttle is pulled back just slightly. I target 2500-2550 RPM and lean to slight stumble then richen till it’s just smooth again (no engine analyzer yet). “Cruise” Fuel burn ranges from 8.0 to a high of 8.8 gph.

Due to all the mountains out here “cruise” altitude is usually 5500 - 9500 ft.

I actually picked up speed when I repitched the prop from 59 —> 56. It could not pull the 59 above 2400 RPM higher than 5000’. Static with 59 was 2260rpm. 56 is 2390rpm.
 
Hi
My plane -
Pa22/20,160 HP, Sullivan wing tips, Vortex generators,EW 1160.
17 gal. Fuel, one person, 26” tires, std gear.
Ground clearance is fine.
Based in Seattle area. Testing for 3-4 months

Installed a test sensenich GA stol 82” prop on my pacer.
Tested all pins at different RPM, timed climbs, all trying to establish some data and collected on a spreadsheet.
Bottom line
Data was difficult to interpret and apply some trends, due to winds, turbulence etc.
Rate of climb was almost always a significant 1000-1200 rpm at 70-80. Mph. Best performance is in slow flight. Faster in pin 5?, no faster than Alum 76/57. Fuel burn slightly higher by 1-2 gph.
About 120 RPM different per pin setting.
My strong 160 hp could not turn this prop> 2300 static and on climb out, despite pin setting. Yes pin 1,2 =2700 rpm in level flight.

Prop accelerates and decelerate ac faster, is very quiet and smooth in level-flight. “ It just Pulls”

Overall this prop makes my Pacer a all new high performer and more enjoyable plane to fly, in back country and getting there. Pin changes are easy with attention needed on torque is the clamp etc., otherwise slight vibrations.
Too many variations with ac engines, weather etc.to tie down data.
I will continue “testing” for some time forward-
Go for it you will not be disappointed.
 
Hi Armstrong,
I will fly another flight test early this week with pin 5 and get real numbers for you, as I am away in Cal.traveling now.
Lately, I fly around with pin 4, giving ~105 mph at 2450.
Thanks for your response
 
Pacer160 said:
Hi
My plane -
Pa22/20,160 HP, Sullivan wing tips, Vortex generators,EW 1160.
17 gal. Fuel, one person, 26” tires, std gear.
Ground clearance is fine.
Based in Seattle area. Testing for 3-4 months

Installed a test sensenich GA stol 82” prop on my pacer.
Tested all pins at different RPM, timed climbs, all trying to establish some data and collected on a spreadsheet.
Bottom line
Data was difficult to interpret and apply some trends, due to winds, turbulence etc.
Rate of climb was almost always a significant 1000-1200 rpm at 70-80. Mph. Best performance is in slow flight. Faster in pin 5?, no faster than Alum 76/57. Fuel burn slightly higher by 1-2 gph.
About 120 RPM different per pin setting.
My strong 160 hp could not turn this prop> 2300 static and on climb out, despite pin setting. Yes pin 1,2 =2700 rpm in level flight.

Prop accelerates and decelerate ac faster, is very quiet and smooth in level-flight. “ It just Pulls”

Overall this prop makes my Pacer a all new high performer and more enjoyable plane to fly, in back country and getting there. Pin changes are easy with attention needed on torque is the clamp etc., otherwise slight vibrations.
Too many variations with ac engines, weather etc.to tie down data.
I will continue “testing” for some time forward-
Go for it you will not be disappointed.
Click to expand...

What tach do you have? If you are relying on your stock mechanical tach then I would be shocked if it was accurate. Using pin 3 I can blow well past redline straight and level (verified using digital and optical tach). You should easily be able to turn higher than 2300 on take off with a 160. At pin 3 you should be turning 2550 to 2600 on take off once you hit about 20 MPH.
 
It’s been a year since the last post. Surely there’s some more Pacer data with this prop by now. Specifically I’m curious about cruise speeds with ABW’s. My 160 is on 29” ABW’s and typically cruises between 115 & 120 mph at 2450 rpm. I’d love better T/O performance and was really hoping this prop would deliver on that front while still maintaining 74dm cruise performance when repitched to a cruise setting.
 
Bender said:
It’s been a year since the last post. Surely there’s some more Pacer data with this prop by now. Specifically I’m curious about cruise speeds with ABW’s. My 160 is on 29” ABW’s and typically cruises between 115 & 120 mph at 2450 rpm. I’d love better T/O performance and was really hoping this prop would deliver on that front while still maintaining 74dm cruise performance when repitched to a cruise setting.
Click to expand...
You might want to verify the accuracy of your AS by flying multiple square patterns at the same AS and recording your ground speed. Take an average of the four legs and check against AS. My AS is 6 mph low.
 
I’ve owned this airplane for 12 years. I’ve done the 4-way gps average many, many times. Pre-rebuild, on 8.50’s I would average 134 mph WOT at 3k ft and in normal cruise would average 126 mph. Closer to 117-118ish now on the 29” ABW’s and 125-126 mph WOT.
 
Bender said:
I’ve owned this airplane for 12 years. I’ve done the 4-way gps average many, many times. Pre-rebuild, on 8.50’s I would average 134 mph WOT at 3k ft and in normal cruise would average 126 mph. Closer to 117-118ish now on the 29” ABW’s and 125-126 mph WOT.
Click to expand...

My observations over the last year.
Details STOL 82”, 160 hp, pa22-20, strong engine,1160 ew aircraft, Goodyear 26’s..
This Sensinich GA prop is a very smooth turning prop, sometimes not sure my 160 is still running, but mainly a stol prop. It is not a cruise prop, even with pin 5.
Want to cruise for those burgers, keep your alum. Fan.
It has been my experience that this prop excels in performance in the 60-75 mph TO range.
Pin changes give ~ 100 RPM difference, with pin 5 just giving 125-127 mph at 2700 wot.
1500 asl, 65 degrees, airspeed is very close with gps test. AS was used for all testing.
Pin 4 offer best all around performance and 5 best for pucker take offs in back country, and smooth long runways, still pulls hard, yet engine to RPM is limited to 2250 static and 2400 CO at 80 mph.
There are too many variables in this search for the best pin setting, aircraft rigging, temp., wing config. ,number of beers etc. to really compare cruise and CO numbers etc.
It takes about 15 minutes to change settings with a spinner on. One has to be VERY detail oriented and careful with in this process, otherwise you will experience vibration and whole process must be started all over.
Summary-
Burrow or buy this prop and see if you like it. Trying to analyze all the numbers is chasing a moving target. Been there many times-

As Steve Pierce once told me” It just pullllls ” and it does. This STOL prop lives up to its name.

Good Luck!
 
One thing to keep in mind. The "pins" have been changed over the years so when one guy says he gets best performance using pin X it might be vastly different than the pin YOU are using.
If you are not using an electronic tach of some sort, DO NOT try and compare RPMS with another owner. Mechanical tachs are not real accurate so like EGTS they tend to show a trend. At the least, spend 150 bucks and get an optical tach to verify your tach.

If is pretty important that you do your own testing to verify the performance numbers for YOUR plane and not rely on someone else's data.

If you want the best data you can get, take a buddy flying with you and let him focus on recording numbers while you focus on flying the plane and holding your airspeeds etc steady in the climb tests. It is really hard to record numbers and fly the plane and do either with much accuracy if you want hard data.

We have done A LOT of various airframe and engine combinations and not a single owner has been disappointed with the performance gains if you are looking for STOL performance and better cruise than the old borer prop. If you really want to dial in your performance, take the larger diameter pins that you will never use and have a machine shop turn them down into "half pitches".
 
I’ve been trying to do a Field Approval for the Sensenich GA prop on a Maule. The problem you run into with any airplane that has a flight manual, the limitations section lists the prop. To change the prop also requires a flight manual supplement and the ACO is the entity that can approve the flight manual supplement. Atlanta ACO insists that it has to be an STC and won’t approve the flight manual supplement! Cessnas don’t have flight manuals, so I can do field approvals for prop changes on them, but not Pipers or Maules. Go figure!
 
Gilbert Pierce said:
According to an FAA seminar I attended Chicago ACO is the go to people for modifications to Viintage airplanes.
Click to expand...
Even Chicago is bad now. The Aircraft Certification branch went through a reorganization a couple years ago. I still haven’t figured it out! In any case, it seems like requests go to the office responsible for the TC. For Piper and Maule, that is Atlanta. My requests went to NY, and they sent them to Atlanta.
 
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