Is this a LSA legal inflight adjustable prop?

[Ed Cesnalis]

I submitted a request for a quote for a 3 blade composite Scimitar shape prop that can change pitch in flight without any input from the pilot.

 

 

If it works out I'll have to get a 914.

 

http://www.princeair...com/carbon.aspx

 

How does the Prince P-TIP propeller change pitch? The method the Prince propeller changes pitch is due to the amount of pull the propeller has. When a propeller is at high rpm and slow airspeed the forward face of the blade has the greatest pull. When the propeller reaches the designed airspeed the propeller face has zero pull. To take advantage of this condition we taper or sweep the leading edge of the Prince propeller profile. When the propeller pulls or cones forward in this high rpm slow airspeed mode the outer portion of the blades pull forward. As the blade pulls forward it will untwist the propeller and offer about 4" less pitch. The pitch will start to move back to the higher pitch carved setting as the airspeed increases. An example of the pulling forward or the proper term, Coning, can be seen on helicopters and propellers if you are looking for it. You may have noticed a helicopter rotor in static running the rotors are straight out or running horizontal, when the collective pitch is applied the blades are now in a bowl shape or coning. The blades will lessen in this coning angle as the helicopter increases in its speed and similar the Prince propeller will proceed back to the carved pitch when the aircraft speed increases.

 

So the Prince propeller will be designed for maximum top speed. A common fixed pitch propeller would suffer in the takeoff and climb mode but the Prince propeller will lessen in pitch and provide a better takeoff and climb and not penalize for Top Speed. Many of our customers report their Top Airspeed the same as the constant speed propeller with still great takeoff performance.

[chanik]

It would fly, so to speak. It is not adjustable in any sense by you. All props flex and change pitch angle when flying to some extent anyway. Warnke used to make wood props with the almost-constant speed claim. They are considered fixed pitch by the FAA

[GlennM]

I wonder how they get around the acceleration of each blade as it bends into the "bowl". Helicopters have hinges for that.

[chanik]

I don't know exactly what his secret sauce is, but if he has thin cord, flexy blades to allow them to twist blade angle then they will bend forward too as I think you mean. It is likely why he designs the prop to have anhedral

[Roger Lee]

Blades like these have been around a while, but haven't really caught on. My guess is some of the advertising is a little too much hype verses real world performance. If they were that revolutionary private owners and aircraft Mfg's would be jumping on them.

 

Ed,

 

You could use this prop if you could get an SLSA MFG to sign off, but he would have to go out and fly off a bunch of test hours and to put on an ELSA wouldn't matter.

[chanik]

I agree with the first part but I'll quibble with that last point. A change of type of propeller is considered a major alteration on an experimental and requires that you be reinspected. Really it will mean you need to log a 5hr phase 1 flight test, since that is what the DAR or FAA rep is likely to assign. (He has to assign at least 5hrs)

[Roger Lee]

Hi Kurt,

 

I have never seen an experimental get re-inspected from a prop change. I have seen several ELSA change without an inspection. and It's talked about on a few other forums.

[Ed Cesnalis]

Roger,

 

I think this is different because it would be a change from ground adjustable to fixed pitch.

[Roger Lee]

Time for me to call the FAA. I'll let you know.

Remember an experimental can do pretty much what ever they want.

[FastEddieB]

I'll look later, but I don't recall my Experimental Operating Limitations referencing re-inspections - only a new course of specified test flights.

 

I'll report back what I find.

[Ed Cesnalis]

Blades like these have been around a while, but haven't really caught on. My guess is some of the advertising is a little too much hype verses real world performance. If they were that revolutionary private owners and aircraft Mfg's would be jumping on them.

 

Not just the scimitar blade design but other methods of air controlled props have been around since at least 1945. http://www.aeromatic.com/home.php

 

My guess is a little different than yours. I guess that most pilots that fly very light aircraft find far less need for adjustable pitch than I do. Once you get into turbos and high powered aircraft the need changed dramatically but those aircraft tend to come with their constant speed prop solutions that work well too.

 

If you don't have a special need, like an under-powered aircraft for a fixed pitch, or big mountains, ...etc. you would just stand pat.

 

It will take someone like me taking the plunge to see for sure.

[Ed Cesnalis]

Given the cost of Neuform and Neuform maintenance I would say this looks cheap enough.

 

 

Mr. Cesnalis,

 

Thank you so very much for the inquiry. The suggested propeller for your application using your Full Throttle Level Flight performance of 100 HP, @ 2350 Propeller RPM, and 140 MPH will be 66" diameter 65" pitch.

 

The cost for our Wood P-TIP Propeller will be $1139.00. For the Better Performance Most Durable Carbon Fiber P-TIP propeller $1441.00. Optional Leading Edge Protection for either propeller will be $100.00.

 

The current delivery time is 7 weeks. A quick delivery option is available, 14 business day delivery with an increase cost of 50%.

 

We also carry Crush Plates cost will be $56.00, Bolt cost $72.00.

 

Leading Edge Erosion Resistant Protective Tape. This is used for protecting against leading edge propeller paint wear due to Sand, Rain, Small Rocks, Grass or other FOD producing debris. A Complete Kit for Wood, Carbon Fiber and Metal Propellers include everything required for installation, with enough material for one two-bladed 84” propeller. $42.00.

 

Smoke Nozzles and 12 volt Solenoid operated Shutoff Valves. Smoke Nozzles $52.00 each and Electric Solenoid Shutoff Valves $65.00.

 

Spinner Cutout Templates. These templates are used to locate the openings for the propeller. The templates are an exact shape of the propeller where it enters the spinner. $35.00, includes templates for each propeller blade.

 

We accept all major credit cards. A minimum of 50% of balance is required to initiate an order.

 

If I can assist further or call you please let me know.

 

 

www.princeaircraft.com

Lonnie Prince

CEO/President

6774 Providence Street

Whitehouse, Ohio 43571

Tel. 419-877-5557

Fax 419-877-5564

lonnie@princeaircraft.com

[Roger Lee]

Talked to the FAA and here's the deal. We're all partial right and wrong. This is for experimental's only. SLSA would have to have factory testing and a lot more hours.

 

You can change the prop. If your plane was assigned a test area for it's phases then all you would have to do is test fly the new prop in that specific area only for 1-5 hours (usually 1-2) and log the flight test. If you had a flight test area in Tucson and moved to Texas you would have to go back to Tucson for the flight test area or get new OP's paperwork and turn in your airworthy cert for a new one. The FSDO would have the authority to inspect again or just give you new papers with a new test area.

If your OP's paperwork does not have a flight test area already assigned then you would need to turn in your airworthy cert and have new paperwork issued with a test area for your plane. Again the FSDO would have the authority to either just give you papers or do an inspection.

 

 

So Ed,

If you have an assigned test area in your paperwork from when you went from SLSA to ELSA then you can do your test and log the results with a new prop. If you don't have that test area assigned because the FSDO forgot to assign one then you need to turn your airworthy cert back in and get a new one.

 

 

If you had a major change to the aircraft structure which a prop is not in the FAA eyes then you would be at the 5 hour test time for things like vortex generators or wing tip changes. These things fall under part 91.319B, Controlability.

 

I would probably blow you away if I told you the 912ULS isn't technically ASTM compliant.

[Ed Cesnalis]

I would probably blow you away if I told you the 912ULS isn't technically ASTM compliant.

 

That's a hell of a closing tease.

[Roger Lee]

yes isn't it. :huh:

[chanik]

And that's why I said quibble. Indeed, many experimental people swap props, never mention it to the FAA and the FAA doesn't seem to care. But legally, you are supposed to. The FAA regulations stipulate at least 5hrs after a modification 21.195 See, even when you call the FAA, they don't quite know.

 

SO it is the classic moral hazard case: practically you can swap props with impunity, legally you should log 5hrs and get reinspected. The FAA here in SJ did not bother to assign a specific flight test area when I asked about major mods. Just don't fly it over the city was the only comment. Fair enough.

[Ed Cesnalis]

http://en.wikipedia.org/wiki/Terrafugia_Transition

 

The Terrafugia Transition uses or at least lists Prince propellers.

[Ed Cesnalis]

Here's an 'almost constant speed', scimitar bladed prop that is aimed at 912ULS.

 

 

http://www.duc-helices.com/technique/swirl.htm

[S3flyer]

The DUC is standard on the Sting S4 and, I believe, Sirius.

 

My Woodcomp S3 is faster than, at least, one S4 but the comparison is probably not valid. The S4 has a significant cowl and canopy redesign and weighs about 30lbs more than my plane.

 

Dan -- any thoughts on the DUC?

[Roger Lee]

Hi Ed,

 

I have two planes come in with the Duc and I have flown in them. I wasn't impressed. Just another prop.

Lots of prop Mfg's make claims, few live up to them and some are on paper only, some in test circumstances only and the fuselage plays a big part in prop performance so clams from Mfg's are not a one size fits all.

[Ed Cesnalis]

Based on name alone 'Warp Drive' beats 'Duc' any day.