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Jacques

NEW propeller for CT

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13 hours ago, Madhatter said:

When you look at one you will see a significant difference from normal props.

 

 

 

INDEED,  the  E-props  is NOT like the ‘others’.,,,,,,,,Roger😘

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21 hours ago, Madhatter said:

Different propellers respond differently to the engine due to blade airfoil design and pitch. With wot of 5500 on the e prop the climb rpm is about 5300. This shows that the blade pitch is changing to accommodate  the increased load as per the design of the propeller. It is acting more like a variable or constant speed propeller. My Neuform prop at wot of 5650 only got 5000 for climb, a more significant load on the engine. The e-prop website data on this has very in depth analysis on this, even enough to satisfy the obsessive engineer ( I am not that type of engineer).

A couple of things here...

1) The "aeroelastic" marketing seems problematic to me.  The prop is entirely carbon fiber, yes?  One of the characteristics of carbon fiber is extreme rigidity and lack of flex.  So it's made of an incredibly rigid material, yet has enough flex to completely change pitch in flight "like a constant speed prop"?  Both things cannot be true.

2)  If it is flexing that much, what does that means in terms of long term fatigue to the part?

The prop may very well be very efficient and even better than most props.  But I think the "aeroelastic" and "like a CS prop" hype is...just that.  Materials science and aerodynamics don't change because a prop company wants it to.

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18 minutes ago, FlyingMonkey said:

A couple of things here...

1) The "aeroelastic" marketing seems problematic to me.  The prop is entirely carbon fiber, yes?  One of the characteristics of carbon fiber is extreme rigidity and lack of flex.  So it's made of an incredibly rigid material, yet has enough flex to completely change pitch in flight "like a constant speed prop"?  Both things cannot be true.

2)  If it is flexing that much, what does that means in terms of long term fatigue to the part?

The prop may very well be very efficient and even better than most props.  But I think the "aeroelastic" and "like a CS prop" hype is...just that.  Materials science and aerodynamics don't change because a prop company wants it to.

The fact that they have closed the gap between WOT(max) and Static(max) shows that the flex happens to a great degree.  It doesn't happen to the degree where WOT is matched but pretty close.  Static(max) is similar to climb and the higher number while still pitched for 5,500 cruise will mean a lot more climb with the same best speed.

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1 hour ago, Ed Cesnalis said:

The fact that they have closed the gap between WOT(max) and Static(max) shows that the flex happens to a great degree.  It doesn't happen to the degree where WOT is matched but pretty close.  Static(max) is similar to climb and the higher number while still pitched for 5,500 cruise will mean a lot more climb with the same best speed.

It could just be a more efficient airfoil shape, it doesn't necessarily invoke flex.  I'm not a materials expert, but I'm skeptical of claims of a prop manufacturer coming up with something prop makers haven't mastered in the last 70 years of making props.  Possible?  Sure.  I'm just not sold on the whole "aeroelastic" thing.  A prop that flexes that much, *especially* one made from super rigid carbon fiber, seems unlikely to last.

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No flex, everyone needs to read their explanation and data, it's all there. I think I have said all I can say about it, time to go to my next project.

 

 

 

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You had no issue with your geographical FSDO approving the "Major Change"?  How did your operating limitations change? Did you get new? My FSDO (ABQ) is being a pita about my changing to a Sensenich - which I have FD approval for.

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1 minute ago, Philip Welsch said:

You had no issue with your geographical FSDO approving the "Major Change"?  How did your operating limitations change? Did you get new? My FSDO (ABQ) is being a pita about my changing to a Sensenich - which I have FD approval for.

If you are S-LSA, and submitted an MRA, then received a LOA from Flight Design, why is the FSDO even involved?

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5 minutes ago, WmInce said:

If you are S-LSA, and submitted an MRA, then received a LOA from Flight Design, why is the FSDO even involved?

I think he is ELSA. I have not looked at the operating limitations for a ELSA, but I have seen plenty of EAB limitations, and changes like a propeller require notification of the FSDO, and possible move back to phase 1 flight testing.

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A major change does require the FSDO be notified, but I don't think you have to do anything other than a flight test (or maybe 5hrs max) if no change beyond LSA limits is anticipated, or if the equipment has been installed on another airplane of the same type.

I have not made any major changes yet to my ELSA, so I don't know for sure.  I have a good relationship with the FAA rep who worked up my conversion, so I will ask him.

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This is not some propeller I found at a yard sale to put on my aircraft. It seems as though a lot of individuals on this forum want debate issues without any data to back them up. With all the talk about this prop it doesn't seem that many have tried to educate themselves but would rather repeat what others say. The Durandal 100 propeller is designed specifically for 912/914 Rotax engines and meets ASTM 2506-13 standard. Has anyone even bothered to know what this is? This meets FAA accepted consensus standards for LSA. This prop is not an "experiment". According to Flight Design there are 85 Flight Design aircraft flying with this prop in other countries. I look at this forum for new info so that I can research it for validity. Unfortunately a lot of professional people in the industry tell me that this forum is not worth looking at with exceptions for a few. I am not ace mechanic or ace engineer, but I try to be. I am looking for facts from people who are experts in their field and spend a lot of time doing so. I have to give Jacques credit for bringing this prop to my attention, this is the kind info I look for. 

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29 minutes ago, Madhatter said:

This is not some propeller I found at a yard sale to put on my aircraft. It seems as though a lot of individuals on this forum want debate issues without any data to back them up. With all the talk about this prop it doesn't seem that many have tried to educate themselves but would rather repeat what others say. The Durandal 100 propeller is designed specifically for 912/914 Rotax engines and meets ASTM 2506-13 standard. Has anyone even bothered to know what this is? This meets FAA accepted consensus standards for LSA. This prop is not an "experiment". According to Flight Design there are 85 Flight Design aircraft flying with this prop in other countries. I look at this forum for new info so that I can research it for validity. Unfortunately a lot of professional people in the industry tell me that this forum is not worth looking at with exceptions for a few. I am not ace mechanic or ace engineer, but I try to be. I am looking for facts from people who are experts in their field and spend a lot of time doing so. I have to give Jacques credit for bringing this prop to my attention, this is the kind info I look for. 

The issue we had just been discussing has nothing to do with the design of the propeller, the standards it was produced under, or that it is being used on other Flight Design aircraft.

It is the issue of complying with the operating limitations that go with your airworthiness certificate. When you changed your airplane to ELSA it became a unique individual aircraft. Your airworthiness certificate was issued with a specific propeller installed. If you change propellers to a different type it is considered a major change in the eyes of the FAA for your unique little airplane. Even with all the testing and approvals you still need to notify the FSDO of the change. Maybe with all the documentation they might allow operation without any further testing, but it is their call not yours to make. If you were still SLSA, then it would be Flight Designs call to make.

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On 12/27/2018 at 9:57 AM, FlyingMonkey said:

It could just be a more efficient airfoil shape, it doesn't necessarily invoke flex.  I'm not a materials expert, but I'm skeptical of claims of a prop manufacturer coming up with something prop makers haven't mastered in the last 70 years of making props.  Possible?  Sure.  I'm just not sold on the whole "aeroelastic" thing.  A prop that flexes that much, *especially* one made from super rigid carbon fiber, seems unlikely to last.

If it was just a more efficient airfoil both static and cruise RPM would increase.  Closing the gap is explained by the heavier load of static ( or take off or climb ) causes enough additional flex, resulting in a flatter enough pitch to close the RPM gap and access more power for take off.

The theory is good, the fact that E-prop can point at a closing gap with their prop is persuasive.

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Just got off the phone with my FAA DAR who did the ELSA certification on my aircraft. He confirmed that there is no issue with me using this propeller and suggested that I record the initial flight data in the logbooks which I had already done.

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1 hour ago, Madhatter said:

My new operating limitations do not specify any propeller type, my old SLSA limitations did.

I haven't seen any operating limitations that specified a propeller type. Neither of the 2 SLSA I have in the shop in the moment list a propeller type in the operating limitations.

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1 hour ago, Madhatter said:

Just got off the phone with my FAA DAR who did the ELSA certification on my aircraft. He confirmed that there is no issue with me using this propeller and suggested that I record the initial flight data in the logbooks which I had already done.

I just took a look at a sample set of operating limitations on a FAA web site. They don't seem to include the requirement to notify the FSDO, but they do require that the aircraft be placed back into phase 1 flight testing for a major change. After the phase 1 testing the appropriate log entries should be made. Changing a propeller from on make and model to a different make and model is a "major change" in my book, and I think the FAA would agree.

6. Flight testing required for phase I operations or as a result of the incorporation of a major change will be conducted in the assigned test area. Flight test operations will only be conducted under VFR day conditions, with the pilot as the sole occupant of the aircraft. This aircraft must be operated for at least 5 hours in the assigned geographic area. Following the satisfactory completion of the required number of flight hours in the flight test area, the pilot must certify in the aircraft records that the aircraft has been shown to comply with FAR 91.319(b) with a statement that includes the following information:

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Like I said earlier based on data and ASTM certification the FAA DAR said no tests were required. This guy used to be a FAA  FSDO manager for all the maintenance inspectors. I don't understand where all you experts come from. I am done with this and don't have any more time for this. 

Edited by Madhatter
Dar

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1 hour ago, Madhatter said:

Like I said earlier based on data and ASTM certification the FAA DAR said no tests were required. This guy used to be a FAA  FSDO manager for all the maintenance inspectors. I don't understand where all you experts come from. I am done with this and don't have any more time for this. 

You are the one calling me an expert, I have never made that claim. I may not have your vast experience, but I do know enough about regulations and maintenance to have an informed opinion. No need to get nasty because my opinion of a major change is different than yours.

Here is my background. I started working in a aircraft shop when I was 16 back in 1980. I earned my A&P in 1982 through Bellville Area College. I have been actively working as a aircraft mechanic since then, and added my IA in 1990. In 1996 I became airport manager of the Olney-Noble Airport, and opened my own FBO providing aircraft maintenance. In 2007 I bought a CTSW and became a dealer for Flight Design. I added Rotax training in 2008, and keep current by doing recurrent Rotax training. Also in 2008 I did Flight Design Factory training on the airframe, and added composite training the next year. I maintain several standard category single engine aircraft, SLSA, and do condition inspections on a few EAB aircraft.

I am also an active CFI teaching bot private and sport pilot students. I recently added commercial glider to my ratings and plan to add glider CFI soon.

 

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No offense to you but I would think the FAA DAR would settle the issue at least for me. I was offered his position before him which I turned down due to liability, too bad I probably could have certified my own plane. I spent years in Cahokia at Parks, so I know Bellville. Again not an issue with you (you have real experiance) but sometimes frustrating to get good factual conversation elsewhere. I don't have all the answers but would like to find them.

Edited by Madhatter
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