Improved Autogyro Flying Qualities Using Automatic Control Methods

[kolibri282]

title: Improved Autogyro Flying Qualities Using Automatic Control Methods
author: Ahmad Shah, S.
comment: This PhD thesis starts with a very comprehensive review of flying qualities criteria for rotor craft. The report is quite long and I have so far only skimmed over the first two dozen or so pages but from what I have seen I think this is a valuable contribution to the topic, so I wanted to share it immediately. Enjoy!
https://theses.gla.ac.uk/39052/1/2018ShahPhD.pdf

 

[Resasi]

Pretty detailed article there Kolibri, looks to be a contribution towards a deeper understanding of why the accident statistics have been as bad as they are.

I am not as advanced in fully understanding the finer mathematical details as many on the Forum, and much of it is way beyond my capabilities, but it would certainly seem to be an advance on some of the research that formed the basis for the BCAR Section T requirements and as such, of possible future benefit to all of us.

It seemed to end with a conclusion that a simple low cost actuated stability system for light gyros would be a way of lowering the risk to pilots, but that further work still had to be done to produce such a system.

 

[Martin W.]

.

wow ... the author sure likes to use a lot of words .... he would be well served to summarize everything in a one page introduction followed by the endless details for the interested designer.

I skimmed through it and he addresses thrust lines ... proper CofG .... stabilizers .... stable rotor design .... things most of us have grasped through the years by experiment.

But from what I can tell he proposes what amounts to an auto-pilot to overrule incorrect pilot actions .... rotorcraft require a very sophisticated system (expensive) and recurrent pilot testing to remain qualified (inconvenient).

Even in the helicopter industry where there are big bucks floating around you do not find a lot of auto-pilot assisted controls .... mostly in the medivac helis and they have the worst safety record of all .... even the S-76 pilot who had all the bells and whistles still chose scud running VFR and killed that famous basketball star ....

Can appreciate all the work he put into his thesis and he will probably get high marks for it .... but will it be practical in real life ? .... I doubt it ... especially in our small market .

.

 

[kolibri282]

Quote: will it be practical in real life /Quote
If you keep it simple such a system would probably be very cheap in terms of hardware. Programming it reliably is another matter, see the nasa guidelines for fault free programs:
https://betterprogramming.pub/the-power-of-10-nasas-rules-for-coding-43ae1764f73d

You definitely have to add a big red mushroom button which you can hit to switch the thing off, when it puts your aircraft in an unrecoverable nose dive...;-)

 

[martin-av8r]

this guy put a auto pilot on his Experimental Homebuild gyro

Laurent Remacle a développé un pilote automatique 100% fonctionnel

Coupe esthétique : 1er place ex-aequo
L'autre vainqueur ex-aequo de cette coupe esthétique édition 2019 est Laurent Remacle qui a construit un autogire original nommé L&T 01. Son aventure de constructeur s'est déroulée sur 5 ans, dont une première année à développer la conception sur ordinateur. Les quatre années suivantes se sont axées sur la fabrication : tournage, fraisage, composites, avionique, traitements de surfaces, peintures... Si l'architecture s'inspire de l'autogire Deluc et plus schématiquement des appareils nord-américains hauts sur pattes avec centre de gravité axé sur le centre de poussée, le design est propre à la création du constructeur, généré à partir d'un modèle 3D SolidWorks. Contrairement à la majorité des autogires commercialisés, dont le châssis est en acier, le L&T 01 repose sur un châssis constitué d'un assemblage de tubes d'aluminium 2017 et 2024. Ce qui porte sa masse à 226 kg, soit beaucoup moins que les autogires équivalents. Le moteur retenu est un Rotax 912 UL boosté par un kit turbo Brako qui porte la puissance à 130 ch, ce qui autorise une vitesse de croisière de 110 km/h. Réservoir, tableau de bord et sièges sont réalisés en carbone/kevlar. Et toujours dans un soucis de légèreté, l'empennage est en bois entoilé. Le rotor et sa tête sont issus de la production de Xavier Averso. La majorité des pièces sont de qualité aéronautique, voir ''MIL'' ; tous les aluminiums sont traités Alodine, avec primer époxy PPG Aerospace et finition PU. Pour cet autogire décidément très original, Laurent Remacle a développé un pilote automatique 100% fonctionnel. Passionné d'ingénierie et ancien industriel, Laurent est pilote autogire depuis une quinzaine d'années. Mais pour lui, voler n'est pas tout : concevoir, créer, fabriquer, mettre au point et réaliser les vols d'essai constitue une expérience passionnante qui permet aussi de partager le savoir avec des gens érudits et fascinants. Le coût de revient du L&T 01 est inférieur à 50 000 euros ttc. Et l'aventure ne s'arrête pas là : un cockpit en deux parties, facilement et rapidement démontable (porte escamotable, version cabriolet), sera exposé au salon de Blois 2020.

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[Martin W.]

Thanks martin .... here is an approximate translation ......

Laurent Remacle has developed a 100% functional autopilot Aesthetic cut: 1st place ex-aequo The other ex-aequo winner of this aesthetic cut edition 2019 is Laurent Remacle who built an original gyroplane named L&T 01. His adventure as a manufacturer took place over 5 years, including a first year to develop computer design. The next four years focused on manufacturing: turning, milling, composites, avionics, surface treatments, paints... If the architecture is inspired by the Deluc gyroplane and more schematically by North American high-legged devices with center of gravity focused on the center of thrust, the design is specific to the creation of the manufacturer, generated from a SolidWorks 3D model. Unlike the majority of gyroplanes on the market, whose chassis is made of steel, the L&T 01 is based on a chassis consisting of an assembly of 2017 and 2024 aluminum tubes. This brings its mass to 226 kg, much less than equivalent gyroplanes. The engine chosen is a Rotax 912 UL boosted by a Brako turbo kit that brings the power to 130 hp, which allows a cruising speed of 110 km / h. Tank, dashboard and seats are made of carbon/kevlar. And always for the sake of lightness, the empennage is made of coated wood. The rotor and its head are from the production of Xavier Averso. The majority of parts are aeronautical grade, see "MIL"; all aluminiums are alodine treated, with PPG Aerospace epoxy premium and PU finish. For this decidedly very original gyroplane, Laurent Remacle has developed a 100% functional autopilot. Passionate about engineering and former industrialist, Laurent has been an autogyro pilot for about fifteen years. But for him, flying is not everything: designing, creating, manufacturing, developing and carrying out test flights is an exciting experience that also allows you to share knowledge with learned and fascinating people. The cost of the L&T 01 is less than 50,000 euros including VAT. And the adventure does not stop there: a two-part cockpit, easily and quickly removable (retractable door, convertible version), will be exhibited at the 2020 Blois Motor Show.​

 

[martin-av8r]

You see the gold servo under the keel cyclic tube

 

[martin-av8r]

Thank you very much Juergen for your good work and contribution to the forum

and for posting this thesis , i think it have very good information in this paper

that can help me on some aspect of my machine setup


Thanks also all other member for your posting contribution on this forum

 

[kolibri282]

Thank you for the kind words, Martin! I have got so much valuable information from the highly knowledgeable members of this forum that I am always glad if I can give back a little bit. Great if the paper helps you to better set up you aircraft and have more fun flying it!

Cheers,

Juergen

 

[Mike G]

Thanks Juergen for an impressive piece of work. I must confess I didn't get to the end, my attention span isn't that great so my comments may be inappropriate.

One thing that struck me and perhaps I've misunderstood because of my diagonal reading is this


It seems to me to say that the rotor speed decreases with increased G loading which is not what I experience.

I may have missed something by not reading it all, but can't help feeling that the author has spent a lot of time trying to solve the stability problem for gyros without decent horizontal stabilizers. Yet most (if not all) of today's commercially available gyros do have decent (all be it improvable) horizontal stabilizers and that the bunting and PIO problem does not seem to me to be the major cause of accidents today.

Mike G

 

[Vance]

In all of the gyroplanes I have flown; my experience has been that the rotor speed increases in maneuvers that exceed one g.

I suspect there is an error in translation or thinking.

 

[martin-av8r]

Thanks Mike for your good reply

i look a bit at it also.. i cant expres myself like i would like to or has good as you in english

the guy talk about stability system on older gyro model with less stability

the need to be cost effective for retrofit on older model

he refer to the UK Montgomerie-Parsons G-UNIV

Quote -- It seems to me to say that the rotor speed decreases with increased G loading which is not what I experience.

like you said that dont also make sense to me

Quote -- I may have missed something by not reading it all, but can't help feeling that the author has spent a lot of time trying to solve the stability problem for gyros without decent horizontal stabilizers. Yet most (if not all) of today's commercially available gyros do have decent (all be it improvable) horizontal stabilizers and that the bunting and PIO problem does not seem to me to be the major cause of accidents today.

you are correct for the little i read , he try to build a system for older... homebuilt gyro that later euro gyro style dont need.. for pitch stability

 

[kolibri282]

Quote: It seems to me to say that the rotor speed decreases with increased G loading /Quote
That one surprised me as well, but he refers to a very abrupt change in rotor load so this is a highly dynamic situation. I am not a pilot but to rapidly increase g load I would assume you have to very quickly increase the disk angle, which would at the same time increase the blade angle of attack thus increasing induced as well as profile drag and perhaps entering retreating blade stall, which perhaps leads to a very short, temporary drop in rotor speed before the rotor adapts to the new load. Just a guess. Unfortunately I could not locate the paper by Gallup that he mentions.