Thrust line vs center of mass

C. Beaty

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Eurotubs are the brainchild of Vittorio Magni. Mr. Magni was a helicopter mechanic who learned how to design gyroplanes by having built a Bensen from plans.

Bill Parsons was the first Magni dealer and believed that horizontal tails were dangerous as well as causing the stiff controls. Bill believed that a vertical gust could blow the tail up into the rotor.

Magni published a service bulletin with the title in English; “Frictioining the Controls” that blamed control pivot friction for the stiff controls. I never paid much attention to that until David Bird (Birdy) in Australia flew one and said; “Where does the friction go when the gyro is sitting on the ground?”

I stuck my nose where it didn’t belong and suggested the heavy controls were most likely caused by nose heavy rotor blades. Greg Grimminger, by then the Magni agent, strongly objected; stating that he had a Magni rotor sample section and it was precisely balanced about the ¼ chord point. As it turned out, Greg had a blade sample from about mid span of the blade.

Averso, the French rotor blade builder, published photos of Magni rotorblade sections from both root and tip ends, showing a highly tapered spar and very overbalanced at the tip end.

It seems to me that most Eurotub designers are not engineers and mostly copy one another.

It is possible that the only qualified gyroplane designer on the other side of the pond is Nicolas Karaolides, designer of the Aviomania line of gyros?
 

fara

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What is this with you and Eurotubs (definitely not used as a term of endearment by you as far as I can gather) Chuck? What do you have against them. They have proven themselves by the 1000's to be stable in flight against scripted stability tests that came out of BCAR Sec T criteria. Raghu gave you the concepts and the math years ago why they are stable. You simply ignore that knowledge like it does not exist. As far as judging Magni or Nicolas. Its just your opinion and I am well aware of your biases which seem to IMHO not add up when placed against the reality of stats of PPOs in Magni or others with HS nor do they align and make a compelling case against Raghu's math or ideas. If you have the data to counter that, I would be happy to hear or see it.

Doug: Yes I know and I think I stated that prop blast is most between 60 to 70% (or 2/3 radius) as you found out. It depends a little bit on the blade design but generally all will fall within this range. The reason I wrote that is your insistence on placing tails immersed in prop stream. Well the tails like MTO, AR-1 and others like it are exactly around 70% of blade radius. But if your preference is for cruciform tail close to the prop and that to you is a superior tail overall, well so be it. Nothing wrong in that.
 

C. Beaty

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I’d be shocked if you didn’t defend Eurotubs, Abid. After all, you bought a set of manufacturing drawings and a license to build Eurotubs

But the bottom line is that all are Bensen derivatives as a result of using the Bensen rotor system.

Bensen combined Arthur Young’s underslung, teetering rotor with Cierva’s tilt head cyclic control system and added his version of the offset gimbal rotorhead, balanced against a trim spring.

Eurotubs using helicopter type cyclic control as does the A&S-18A would be much more difficult to fly and far more dangerous.
 
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fara

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I’d be shocked if you didn’t defend Eurotubs, Abid. After all, you bought a set of manufacturing drawings and a license to build Eurotubs

But the bottom line is that all are Bensen derivatives as a result of using the Bensen rotor system.

Bensen combined Arthur Young’s underslung, teetering rotor with Cierva’s tilt head cyclic control system and added his version of the offset gimbal rotorhead, balanced against a trim spring.

Eurotubs using helicopter type cyclic control as does the A&S-18A would be much more difficult to fly and far more dangerous.
Haha and I'd be surprised if you didn't dis them because they do not follow your prescription for achieving stability and instead rely on the HS for getting aoa stability. But that is not a meaningful statement. That is just a side play. I don't see Magni or others who make those types of machines come here and say things about "Erector Sets" or "Eiffel Towers".

I asked and have always asked if you have data that shows from the 6000+ units of the so called Eurotubs (they are more appropriately the design configuration that was finally set out by Juka who is an aeronautical engineer) have had significant number of PPOs in the last 25 years they have been flying?

Also, about why Raghu thought and showed the concepts and Physics of why these gyroplanes indeed are stable when he didn't have to care one way or the other then what is your counter to those concepts if any that make Raghu's work to be so easily set aside? Point by point. I know you know his work and have known it for years so lets just take his work in this reference.

And lastly, why do you think these machines are able to certify to BCAR Sec T which is quite stringent even on long period stability (when gyroplanes are not flying instrument flights).
 
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C. Beaty

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I got Raghu his first and only ride in a gyro; I asked Rusty Nance to give Raghu a ride in his 2-place Dominator.

Jean Fourcade is a far more credible source of advanced gyroplane theory.

But that’s all beside the point; the safety record of all gyros has improved over the years as a result of better training and improved design. And McCullough target drone engines have all been used up.

Eurotubs are not the handiwork of Jukka Tervamaki. Jukka interned at Bensen and the model he sold Magni was pretty much CLT. Magni tried to make his rendition of the prototype he purchased from Jukka look like a Ferrari. Also, Jukka produced some of the earliest FRP rotorblades, I think even beating MBB’s predecessor.
 
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fara

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I got Raghu his first and only ride in a gyro; I asked Rusty Nance to give Raghu a ride in his 2-place Dominator.

Jean Fourcade is a far more credible source of advanced gyroplane theory.

But that’s all beside the point; the safety record of all gyros has improved over the years as a result of better training and improved design. And McCullough target drone engines have all been used up.

Eurotubs are not the handiwork of Jukka Tervamaki. Jukka interned at Bensen and the model he sold Magni was pretty much CLT. Magni tried to make his rendition of the prototype he purchased from Jukka look like a Ferrari. Also, Jukka produced some of the earliest FRP rotorblades, I think even beating MBB’s predecessor.
Of course Raghu is not credible because he had few hours in a gyroplane. You know because to understand gyroplane stability you have to be an expert pilot not an engineer or a scientist. You know Chuck that is just not the case.

Jean Fourcade simply agrees with your view so he is a credible source of "advanced gyroplane theory".
Chuck, I asked what are your counters to Raghu's work point by point and safety regarding PPO on 6000 Eurotubs with HS?

I think this configuration is very much the work of Jukka. Of course Jukka interned with Bensen. So what. Everything is built on something and no Jukka is not obsessed with CLT or LTL. That is not his idea. If anything I can tell you from brief interaction with Jukka that he would very much be in Raghu's camp of why these gyroplanes are stable and why the data aligns with that theory.
 
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jm-urbani

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jean-fourcade never agree with anyone except with maths and physics laws .... this man works for the european Nasa

the ctl is not an obsession but safety should be everyone's obsession
 
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jm-urbani

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But that’s all beside the point; the safety record of all gyros has improved over the years as a result of better training and improved design. And McCullough target drone engines have all been used up.
Chuck safety records are bettering OK , but only one death is too much ... and zero G accidents still happen without alerting the authorities ...

one of my hangar mate took off and crashed, his gyro fall rotor head first on the runway from 20m high

many people arround said that he had not secured his seat belt and that when he realized it he gave a slight left stick input followed by a violent right stick input flipping the gyro upside down ... but if the right stick imput was the cause of the accident the gyro would have drifted on the right and would not have fallen on the runway ...

just try to take off and arrived at mid runway put your stick right .. you will immediatly head on the right far from the runway

in order the to flip a gyro up side down on the rolling axis without drifting out of the runway the gyro has to be in a zero G situation full throttle, the huge engine torque is responsible,

the Bureau Enquète Accident said that the rotor was not providing lift any more

of course it means that the gyro was in a zero G situation, but the bea did not blame the engine torque even if it he mentioned in the report that the rotax computer showed that the engine was full throttle until the impact.

of course the BEA did not blame the absence of a aviomania like HS or the absence of a tall tail in the prop-wash because it would have condemn all the European gyros or even the activity itself.

but if the gyro had been correctly designed like the Aviomania gyros or if the gyro had had a tall tail with the HS in the prop-wash my mate would still be there .. and it is crazy to think that just because gyros do not have a correct HS preventing torque or at least a tall tail and a HS in the prop-wash this guy died ..

Chuck you are politically correct when you speak of improved safety records, but we should speak of improved death Toll instead.
 
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C. Beaty

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Abid, you claim to have studied math and physics at USF but as it turned out, you took a technician level course in micro electronics. Is it possible that someone read math and physics to you while you were looking at a semiconductor chip through a binocular microscope, trying to make a gold wire stick to a pad on the chip?

Whatever the case, Raghu did consulting work on the side and it seems likely that he was hired by MTO to write that report.

The only person I’m in complete agreement with is Juan de la Cierva. All of his gyroplanes were CLT with balance between belly fin and dorsal fin to eliminate throttle/yaw coupling and with differential pitch on the horizontal stabilizer to eliminate propeller/torque roll. Could he have been mistaken?
 
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C. Beaty

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the Bureau Enquète Accident said that the rotor was not providing lift any more

of course it means that the gyro was in a zero G situation, but the bea did not blame the engine torque even if it he mentioned in the report that the rotax computer showed that the engine was full throttle until the impact.
JM, government agencies do the best they can but they can’t be experts in everything.

A number of years ago, a friend of mine, Smokey, was at an airport with gyro when an FAA accident investigator arrived to investigate a fatal gyro accident. The investigator asked Smokey for assistance. Smokey said; “sure.”

They came to the wreckage and the investigator said: “Where’s the tail rotor?” Smokey said; “I don’t know.”

The investigator’s preliminary report blamed the accident on ‘loss of tail rotor.’
 

jm-urbani

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yes , Ron Herron narrated the day the inspector came to check it's first tractor gyro ... the inspector had a look to the electric pre spinner and asked Ron how long the battery can sustain flight ?
how come an inspector don't know about autorotation ?

as for french gyro accidents, of course the bea usually asks tek details to the eurotubs gyroplane actors who are not going to blame eurotubs design flaws
 
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Rotormouse

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Section T approval has little credibility when concessions can be bought. It’s not the gold standard some would have us believe.

I prefer hands on experience over theory, I don’t have the ability to relate to cold facts and figures on a page – what speaks to me is the touch of three-dimensional reality in the sky. When decades of such experience are coupled with understanding of maths, physics etc, like Jean, Chuck and Doug, there’s no contest. Abid isn’t doing himself any favours. Agree to disagree and let it go.
 

raghu

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Whatever the case, Raghu did consulting work on the side and it seems likely that he was hired by MTO to write that report.
CB, my friend what is this about? Why do you spread misinformation (or should I say fake news) ? What report are you talking about? Can you please correct your post? I have never consulted in any way or received any money from any gyro manufacturer. My interest is purely amateur and intellectual curiosity. My findings are what I best understand them to be-they could be correct or wrong. I am happy to discuss the work on its merits but don't have any interest in mud slinging.
 

fara

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CB, my friend what is this about? Why do you spread misinformation (or should I say fake news) ? What report are you talking about? Can you please correct your post? I have never consulted in any way or received any money from any gyro manufacturer. My interest is purely amateur and intellectual curiosity. My findings are what I best understand them to be-they could be correct or wrong. I am happy to discuss the work on its merits but don't have any interest in mud slinging.
Raghu
Good to see you are still here. I have not seen a post from you in years.
I thank you for truly getting deeper than high school Physics and providing an explanation that actually jives with reality and accident stats about PPO
 

fara

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Section T approval has little credibility when concessions can be bought. It’s not the gold standard some would have us believe.

I prefer hands on experience over theory, I don’t have the ability to relate to cold facts and figures on a page – what speaks to me is the touch of three-dimensional reality in the sky. When decades of such experience are coupled with understanding of maths, physics etc, like Jean, Chuck and Doug, there’s no contest. Abid isn’t doing himself any favours. Agree to disagree and let it go.
all certification standards even including Part 23 have provisions for exceptions but they do not apply to something as fundamental as longitudinal stability. Sec T longitudinal stability requirements are more stringent than Part 27 or CAR 4. The type certificates Gyroplanes in the US from the 60’s may not pass those requirements. Though that’s an educated guess only on my part.
 

fara

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jean-fourcade never agree with anyone except with maths and physics laws .... this man works for the european Nasa

the ctl is not an obsession but safety should be everyone's obsession
good for Jean. Then he can tell Chuck how to properly counter Raghu’s concepts and math and explain why every year from a fleet of thousands we don’t hear of dozens of PPO in Gyroplanes that are AoA stable. Easy. Stop appealing to authority and give clear explanation and counter real world data.
 

jm-urbani

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Be sure that I will read with attention Sir Raghu's scientific papers, let me know where they are published and I will with pleasure
If Mr Raghu issues a scientific paper showing that a gyroplane in Zero G at full power with a magni/mto/ela rudder can't flip up-side down on it's rolling axis I will carefully read this and if it convinces me I will be reassured... for the moment I am not reassured
As for the Authorities what do you fear as you claim that there is no problem ?
do you think that authorities could ban low profile gyros with magni/mto/ela style rudder only because I am speaking my mind on the internet ?
be reassured they haven't so far and there is little chance they will
99.9 % of the stock gyros are low profile gyros, so the competition of the High profile gyros doesn't even exists anymore so you are not commercially at risk at all Abid
I have my opinion based on the scientific papers I have read, you have yours based on other scientific papers and we are speaking on a forum where each reader will form his own opinion, if your point of View is the scientifically exact one, or if your force of conviction is the strongest, 99% of the readers will think you are right.
but you won't manage to prevent people to speak their mind.
 
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fara

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Abid, you claim to have studied math and physics at USF but as it turned out, you took a technician level course in micro electronics. Is it possible that someone read math and physics to you while you were looking at a semiconductor chip through a binocular microscope, trying to make a gold wire stick to a pad on the chip?

Whatever the case, Raghu did consulting work on the side and it seems likely that he was hired by MTO to write that report.

The only person I’m in complete agreement with is Juan de la Cierva. All of his gyroplanes were CLT with balance between belly fin and dorsal fin to eliminate throttle/yaw coupling and with differential pitch on the horizontal stabilizer to eliminate propeller/torque roll. Could he have been mistaken?
]

chuck before USF I already had dual major in engineering degrees. USF I did computer science.

I do not think your mud slinging merits a proper answer. If you don’t have data to counter stats or proper clear explanations for why Raghu’s work for instance isn’t valid, try and refrain from mud slinging. It doesn’t suit your age nor is it civil.
 

fara

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Be sure that I will read with attention Sir Raghu's scientific papers, let me know where they are published and I will with pleasure
If Mr Raghu issues a scientific paper showing that a gyroplane in Zero G at full power with a magni/mto/ela rudder can't flip up-side down on it's rolling axis I will carefully read this and if it convinces me I will be reassured... for the moment I am not reassured
As for the Authorities what do you fear as you claim that there is no problem ?
do you think that authorities could ban low profile gyros with magni/mto/ela style rudder only because I am speaking my mind on the internet ?
be reassured they haven't so far and there is little chance they will
99.9 % of the stock gyros are low profile gyros, so the competition of the High profile gyros doesn't even exists anymore so you are not commercially at risk at all Abid
I have my opinion based on the scientific papers I have read, you have yours based on other scientific papers and we are speaking on a forum where each reader will form his own opinion, if your point of View is the scientifically exact one, or if your force of conviction is the strongest, 99% of the readers will think you are right.
but you won't manage to prevent people to speak their mind.
you will have to go as far back as 2012 and go forward to 2015 to read all of Raghu’s posts on the subject to get the full context. When his work did not agree with this forum’s pre-eminent self claimed aerospace engineering Personality specializing in controls and stability, he got silently put aside.

Raghu has no dog in the fight but he had to put up with a lot. The problem is real world stats lean heavily in his favor. Theories have to explain reality not the other way around. Good luck searching, reading and understanding.
 

jm-urbani

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I won't make any Archaeology in the forum, I am waiting for the same kind of paper then Jean fourcade's one, I am sure he can do this in order to reassure every body showing that a gyroplane in Zero G at full power with a magni/mto/ela rudder can't flip up-side down on it's rolling axis
 
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