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E-Props ...who has first hand experience with these


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As I understand it, the CS E-prop is not yet available and the one referred to in Mark's customer's reports is a fixed one.  And a feature of these props is their light weight compared to the competition.

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Gday, Finally the results of testing the EProp in comparison to Bolly and Kool (Luga), using manifold pressure to set engine power exactly equal for each. Once again surprising results that

First tests with the variable pitch propeller     

All CSU (I gather thats what your commenting on Bruce) are expensive. I personally dont think they are worth the cost for the performance for our type of aircraft.   Posted above is the std

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All CSU (I gather thats what your commenting on Bruce) are expensive. I personally dont think they are worth the cost for the performance for our type of aircraft.

 

Posted above is the std type ground adjustable prop.

 

I believe Eprop are finalizing testing on their range of props for the Jabiru engines now as well

 

 

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3 hours ago, Bruce Tuncks said:

As well as the cost, my problem would be with the weight of the prop plus mechanism. But surely there would be an increase in the max speed, in comparison to a fixed pitch prop.

I have posted a few examples before of aircraft that have a fixed or constant speed option such as the Tecnam p2010, a 130knot aircraft. The numbers show only a small improvement in takeoff to 50 feet and slightly higher climb rate. Top speed not much difference. The Cessna 172 and piper Cherokee continue today with a fixed propellers. The Cessna constant speed version, the xp172 only lasted 3? years in the market place.

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I like that story thruster. The wooden Jabiru prop is so simple and light that I would need some good figures to change for a CSU. For example, I would want about 5 knots more top speed. AND what if the extra loading by the prop caused less engine reliability?

 I have actually been worrying about this after changing from a 40" to a 44" prop on my Jabiru, I think it cruises a few knots faster and I don't notice any change on the take-off.   

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Bruce, apparently you get another 3 to 5 kts  with the composite jab prop on your machine... (GATHER U HAVE THE WOOD) . stiffer.

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On 21/03/2021 at 12:21 PM, Thruster88 said:

I have posted a few examples before of aircraft that have a fixed or constant speed option such as the Tecnam p2010, a 130knot aircraft. The numbers show only a small improvement in takeoff to 50 feet and slightly higher climb rate. Top speed not much difference. The Cessna 172 and piper Cherokee continue today with a fixed propellers. The Cessna constant speed version, the xp172 only lasted 3? years in the market place.

Hardly the whole story:

 

a. Hight speed - An in flight adjustable (IFA) will not improve on a fixed pitch optimised for this phase of flight.

b. Take off/Climb - An in flight adjustable will not improve on a fixed pitch optimised for this phase of flight.

 

An in flight adjustable will give you good performance in all phases of flight from short field take off to high speed cruise - this is a simple fact that can not be disputed.

 

The down side of an IFA are: Greater weight , Cost & Complexity (construction and management) - the converse is true of fixed pitch.

 

In the real world, most fixed pitch propelled aircraft owners have selected the propeller pitch angle that will best suit the range of activities anticipated for that aircraft - this is a COMPROMISE decision and will mean that the aircraft will have underwhelming performance (below its optimum) outside the selected range.

 

The aircraft T88 has exampled are generally optimised for high speed climb - that is take off distance will be good (safe) climb out good (safe) and cruise acceptable but not fuel efficient. They can be optimised for take off with further compromises and of course for high speed cruise but then take ground role will be extended (possibly unsafe) climb out will be anemic (possibly unsafe).

 

Airframe characteristics must also be taken into consideration - a draggy airframe can not be made to exceed its potential, at a given engine power (T88's examples are all pretty draggy) a heavy airframe will have a longer ground run and climb out, for a given engine power - this is just physics.

 

I like to illustrate what can be done with just a 100 hp Rotax/IFA , meticulous attention to airframe build/detail by using mention Robin Austins amazing aircraft (http://www.worldrecordplane.com/

 

For most RAA and lighter end of GA (sub 180 hp) the flexibility delivered by an IFA is hard to justify on economic grounds alone. If you have a need/desire to optimise your aircrafts FULL flight envelope you will have to have an IFA (& bugger the cost)

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indeed. for every prop and prop pitch, there is a maximum efficiency airspeed.  

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On 21/03/2021 at 12:21 PM, Thruster88 said:

...........................The Cessna constant speed version, the xp172 only lasted 3? years in the market place.

Too many years ago, I obtained my Constant Speed/Retractable Undercarriage endorsements in a Cessna 172. From aged/defective memory, it also had a 180 hp engine, significantly more powerful than the 6 & 4 cylinder variants I had flown previously . It seemed a big step up at the time, was about 10 + knots faster than its best fixed pitch/undercarriage sibling, had autopilot and other than an intermittently defective radio, was very nice (whatever that means) to fly. It cost a bit more to hire but then it was a real aircraft and worth every cent.

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