Question from the web

[Abid]

You are right.
0.5 G when the rrpm has not yet had time to decrease corresponds in reality to a zero angle of attack of the disc. This is due to the positive pitch setting of the blades which still lifts as an helicopter
And 0 G requires a disc angle of attack of about -10 degrees for the same reason.
The flow then clearly passes through the disk from top to bottom without any deflection
The longitudinal flapping angle is at this time only 0.7 degrees.
The idea of a catastrophic flapping at G = 0 is completely wrong (*)
The problem when G = 0 is that the orientation of a zero force by the stick is no longer sufficient to oppose to the High Thrust Line of the propeller
View attachment 1157802

(*) It is only when we want to restore G= 1 with rrpm has become slower than 85% of nominal rrpm that will produce the flapping divergence.

85% is extremely conservative Jean. I know we can get lower than that and still recover not that I am saying anyone should try it but I know people who do go below 85% of the RRPM and come out ok restoring G load. I think the real red line is somewhere around 70 to 75% but going there is like playing with live fire but certainly people are doing it even at air shows and one day that bomb is going to go off right at an air show in front of everyone.

 

[Abid]

I do not agree with the intention of this statement... but it is absolutely true!! The correct view of this statement is that a correctly design tail (among other things) will offer benefits throughtout the gyroplane's flight envelope..... not in just a selected moment, which unfortunetly is what some designs currently offer.

As Doug Riley said it can be done with careful, correct and knowledgeable design.... and this does not only includes the tail.....

We have doing it since 2007!!! For more than 15 years we showed what the benefits of a correct design are but still people are arguing about it.

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The intention is clear and I don’t think you get it. You can create an effective asymmetrical thrust with a HS that is as wide or slightly wider than prop diameter even if it does not have different incidence left to right or have different airfoil left to right. The effective diameter Ferenc win AoA is around 6 degrees in such a tail from left to right because how propeller stream hits it.

 

[Jean Claude]

85% is extremely conservative Jean. I know we can get lower than that and still recover not that I am saying anyone should try it but I know people who do go below 85% of the RRPM and come out ok restoring G load. I think the real red line is somewhere around 70 to 75% but going there is like playing with live fire but certainly people are doing it even at air shows and one day that bomb is going to go off right at an air show in front of everyone.

Certainly, Abid, because this 85% is only the result of theoretical calculations assuming 1 G restored instantly, which is impossible in practice.
On the other hand, in the absence of recordings, how can we know in which conditions of smoothness the pilots could restore 1 G from 75% of nominal rrpm?
I can try to simulate a slower restoration to 1 G, for example in 0,5 s, to check if such a difference is explained

 

[Mike G]

Abid,
Working with Jean Claude, I have learned that you contradict Jean Claude at your ego's peril. He has the annoying habit of being right.
Opinions count for nothing, if you believe it's nearer to 70-75% get you Embray engineer to demonstrate it mathematically.
Or
plug in the remote WiFi link for the GWS and I'll set the bunting red alarm limit to 75% without the current 3 second prediction for you and you can demonstrate that you're right by bunting to 0.5g until you hit your 75% Rrpm value and recovering. If you're right I'll bow to your opinion, if you're wrong I'll send flowers to your widow.
Mike G

 

[Abid]

Certainly, Abid, because this 85% is only the result of theoretical calculations assuming 1 G restored instantly, which is impossible in practice.
On the other hand, in the absence of recordings, how can we know in which conditions of smoothness the pilots could restore 1 G from 75% of nominal rrpm?
I can try to simulate a slower restoration to 1 G, for example in 0,5 s, to check if such a difference is explained

Hi Jean:
The person that sees this 75% decay before retrieval is a friend of the guy who has been working with Mike G on GWS and PB4 in the US. Although I have to say he has been so busy with his business technical work that GWS has basically been out of sight in his world for now. We should ask him to install GWS in his gyroplane so we can get those recordings. I simply do not have the bravery to try and do the crazy stuff he does in a gyroplane and I doubt I have the timing or the skill either.

 

[Abid]

Abid,
Working with Jean Claude, I have learned that you contradict Jean Claude at your ego's peril. He has the annoying habit of being right.
Opinions count for nothing, if you believe it's nearer to 70-75% get you Embray engineer to demonstrate it mathematically.
Or
plug in the remote WiFi link for the GWS and I'll set the bunting red alarm limit to 75% without the current 3 second prediction for you and you can demonstrate that you're right by bunting to 0.5g until you hit your 75% Rrpm value and recovering. If you're right I'll bow to your opinion, if you're wrong I'll send flowers to your widow.
Mike G

LOL. You should ask Chris to put the GWS in his friends gyroplane to get the recording and graph to see if he does get down to 75% like he says. I do not think he has any reason to make it up though to me.