Sensenich’s Ground-Adjustable Props Available For Light GA Aircraft

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Sensenich Propeller has announced FAA Part 35 type certification for its G-Series ground-adjustable carbon-fiber propellers. Designed for engines in the 125-HP to 180-HP range, the propeller comes in diameters of 72 to 82 inches. Current supplemental type certificates are available for the 82-inch-diameter version on the Piper PA-18-150 series Super Cub powered by O-360 engines.

Work is underway on additional approvals for more Piper, Cessna, American Champion, Cub Crafter and Grumman models, according to Sensenich.

The propellers’ lighter-weight scimitar-profile “maximize performance while reducing acoustic signature,” according to Sensenich. Monocoque construction lowers the propellers’ weight by 15 to 20 pounds compared to fixed-pitch aluminum and more than 50 pounds compared to some constant-speed propellers. The manufacturer added that reduction in rotating mass yields quicker throttle and control response.

The ground-adjustable propeller makes pitch change quick and easy, says Sensenich, adding that stainless steel shields protect against erosion and foreign object damage (FOD), increasing service life. The company also claims the G-Series propellers’ ease of installation and operation “deliver meaningful and economical improvements without the negative installation cost, service interval, and operating changes associated with constant-speed propeller conversions.”

Mark Phelps is a senior editor at AVweb. He is an instrument rated private pilot and former owner of a Grumman American AA1B and a V-tail Bonanza.

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9 COMMENTS

  1. This is great! As someone who went from a constant speed prop to a Sensenich ground adjustable on an experimental I have nothing but high praise. Very similar performance, less service, much lighter weight, better customer support. Glad our certified brethren can now join- and wish Sensenich all the best commercial success, they deserve it.

  2. I am not so sure about this. Seems like an accident waiting to happen. A pilot adjusts the propeller for one kind and type of field, goes to another entirely different field, and forgets to readjust it. At least with a constant speed propeller, one can adjust it in flight via the controls.

    • There’s nothing new about ground-adjustable propellers. However, adjustment of such a propeller would seem to NOT fall under the “preventive maintenance” that an owner/operator may perform, and would instead seem to fall under a “minor repair or alteration” requiring an A&P to perform. Of course, the builder of an experimental has such authority, but for a certified aircraft, it would appear to require an A&P to make the adjustment.

      In any case, this is no different than installing a climb prop vs a cruise prop. The adjustment range would still be limited to the TC of the aircraft’s allowable pitch ranges. It’s just that you don’t have to physically uninstall and reinstall a different prop each time.

  3. CS obviously better except for the weight cost and complexity but this can be used on solid crank engines and is better in theory to FP.

    I’d like one for my Maule with an O-360 with a Sensenich OEM. Hopefully, since the same engine as the planes already STC’ed would be a possibility.

  4. Hmm … I noticed a night/day difference when I changed from a fixed pitch to a CS prop in our Glasair. Even if I could mimic the performance of a CS prop in flight using a ground-adjustable prop (I would set it to cruise at 2450 rpm, which was optimal for us), I would not obtain the braking action on landing that the CS prop gave us. (Not to mention the better climb, since we could turn 2700 rpm while climbing.) When I pulled back on the throttle with the CS, it was almost like having Beta on the prop as the blade angle changed. My landing roll reduced to half, which, in addition to safety factor, saved wear & tear on brakes & tires.

    As for the weight of a CS – we actually welcomed it, since we needed to move our CG forward.

    But I understand the desire for something less expensive, easier to install than a current hydraulically operated CS prop.

    So I throw this idea into the public domain for some enterprising company to use. In this day and age of wireless this or that, how about an electrically operated “in flight” adjustable prop that is driven by a BT connected Brain Box? (With appropriate Fail-Safe modes if BT is lost, etc.) The Brain Box would send a signal to the adjuster in the hub, so as to maintain (more or less) as constant RPM. Even if it were a coarse adjustment, offering only 3 settings (Take off, cruise, idle) it would be better than one fixed pitch.

    With battery technology today, it seems like it should be possible to mount a small cylindrical battery on the CL of the hub that drives the “adjuster.” Perhaps the battery could be charged wirelessly in flight, as is now down with wireless charges for our phones, tablets, etc. Or, alternatively, the nose of the spinner could have some vanes on it, to make it spin a bit to keep the battery charged.

    Essentially, a hybrid between today’s CS prop and a ground adjustable prop.

    Perhaps someone in the Experimental market could start with this new Sensenich and add to the hub to see if it this idea will work? (FWIW, I did modify the tips on my Hartzell prop and picked up a few knots. So I would try this. But my flying days are just about over.)

  5. Ha! Interesting idea Era. But I’d let someone else test it out 😉

    Honestly I’d say that most pilots will tinker to get what they like and then mostly leave it there. It takes about 30 minutes for me to adjust (take spinner off, loosen bolts, adjust prop, torque bolts progressively, and then put the spinner back on). This works great for changes in mission- for me most flying is local punctuated by longer XC trips, I’d say I adjust about 6x a year. The Sensenich pin system is what won me over vs WW. The pins are so simple to use and quite effective, definitely more user friendly than a protractor.

    The safety bit about “forgetting” to reset the propeller is honestly a bit laughable. On your runup you’re also checking static RPM so you definitely notice something. The pitch changes aren’t that drastic so I’m sure it can be done but I’d put it in the category of density altitude/fuel mismanagement etc. At least a ground adjustable gives you the option to adjust for your operations. I had a long XC last year and pitched it waaay out, with a 2100 static pitch. The plane had no issues getting off the ground and climbing fully loaded (definitely slower though) but then really worked well at 10,000 ft.

    As the fellow with the Glasair pointed out; not for everyone. I do miss the braking action but as my stall speed is 40 kts light, I don’t really miss it that much. And my C of G was too far forward so any nose weight off was great. I am also biased as I saw the worst of the Constant Speed world. The prop was sold as working for O 360s, then experienced difficulties and the factory pulled the support with a letter… all without supporting the folks who had bought for 360s. It leaked, blades got play, and I spent $$$ to repair and wound up where i started while no longer trusting the prop. Replacement would have been 3x the price of this prop and I was not enthused to support a company that showed they did not stand by their word. Meanwhile Sensenich did send me a wrong hub by accident. Instead of being greeted with suspicion and cagey answers as the previous company, I had the new part shipped to me at no charge with no hassle. Much better.

    In the end it seems like it is a great addition to the certified world; Sensenich builds a fine product and it could be a great fit for a 172 or the Maule mentioned above. It is price competitive, has real ramp sex appeal (don’t tell me you don’t like seeing that carbon fiber weave…), and lets you fine tune to your mission.

  6. The Beech Roby prop was an electrically-controllable prop which could be manipulated with either a “increase/decrease” toggle-switch…or a rheostat …. to change pitch. The later versions would even behave as a CS prop with some simple electronics. It’s funny how some things that come around… are really not much different than what existed decades ago.