Hi rotaryeng

Can someone please assist with a technical question regarding a RX8 4 port low power manual engine 190 bhp engine will be used in helicopter.

We would like to find out what the rotational inertia is so a damper can be designed for the pulsation

Also can someone clue me up regarding the purchase of aluminium end plates, where to purchase and what should the cost be,

Would very much appreciate your assistance

Kind regards George



Kind Regards George Crooks


I have no idea on the rotational inertia but here is a coupling design that has evolved from years of experience.

Aluminum end plates are available from Racing Beat.

http://www.racingbeat.com/RX7-1993-1995/Rotor-Intermediate-Housings.html





They are peripheral exhaust and do not use the RX8 side exhaust.
In that case you might as well sell the 4 port RX8 engine and buy a 3rd gen RX7 engine and base it on those rotor housings, e-shaft and rotors.

I recommend p-port intake as well. In that case you will have 250 HP to work with at 7500 RPM.


Paul Lamar

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George, If you have a 3D program I can send you an IGES of the coupler.

Paul Lamar

I was told by a relative, working in the aeronautical engineering field, that helicopters are highly complex and extremely difficult to design, and the people that are known for being able to design a working helicopter are very few, and known to everybody in the industry.

A French engineer having proven his expertise in helicopter design had an argument with his employer, in certain businesses, nobody would hire you if you leave another company in the field, as this may result in transmitting know-how, patents and other industrial secrets to competitors, and when the Spanish govt knew this, it was in the 60's, they hired that expert who built several models of helicopters, if I remember well, under the mark 'AISA', for Industrial Aeronautics in Spanish.

Around 1986, I made a car trip for reasons of work from Madrid to Oviedo (Asturias) and while passing next to a wreckage-recycling lot, I saw one of these  helicopters standing among the many cars there.

I ignore completely the final destination of this piece, and as roads changed since then, it would be extremely difficult finding the place again, but a similar thing seems having happened with at least one of the prototypes of Wankel powered Corvettes, that was bought by a British writer when it was about to be put into pieces, and is shown in local Wankel lover's meetings, but never making the engine run, previously, two GM Wankel powered Corvettes were at exhibition in the Ford's Dearborn Museum in Detroit, at least, it were there in March 1988.

I read somebody stating that these Wankel Powered Corvettes, one with two, and the other with four rotors, won't be allowed today going on roads or streets, as none of two met the rules about headlights.


Regards. Salut †

Jose Gros-Aymerich Madrid, Spain



Hello Jose Gros-Aymerich, and all who may be interested

I trust my mail finds you well in health and in good spirits


There are monuments of all kind in backyards all over the world, it goes without saying that if I fail to plan properly then it can be said that I have planned to fail.

With that said there is a poem that suits the situation it is called "the bridge builder" available on the internet and worth a read if you like simple wisdom, if not and only here for self

benefit, my suggestion is don't bother



Projects fail for all sorts of reasons and I accept your comments as very valid and as you might notice that failure happens to companies much, much larger than my self



I am seeking information and contacts; there are a number of independent aeronautical engineers over the world that have experience a variety of areas, the helicopter I am building is a Scorpion 2 seater  for which having been of 1970s technology it was a good helicopter with many being built from kits and for sale on the internet today, they started out with an outboard boat engine and grew from there , there are only just a few modification that I intend to carry out which is engine and rotor.



Right up to today popular helicopters have the power of the engine transmitted through V belts, which have failed in the past and who know about the future.




The Scorpion has V belts driving both the main rotor and the tail rotor; I plan to make the aircraft safer by employing much safer means of driving the rotors, and more pilot friendly.



The engineer that I am working with or will be in January will be designing the reduction box for the helicopter , he has done this previously for a helicopter fitted with a diesel engine,  he has advised me to change the main rotor system to one which is pilot operator friendly,

which is a fully articulated system, he has also successfully deigned a fully articulated system previously so thus my enquirys about the rotational inertia of the Mazda  rotary engine and again regarding the one rotor turbo.

I have met a man who trades under the name Billet INC, (he has a
website) who builds some lovely rotary stuff a little expensive for me, but good stuff; he is a Drag Racer and builds for that industry.
His rotary engines hold world records and as a hands on motor mechanic for many years I can appreciate his work. He suggested that I take a look at the single rotor rotary saying he could build a turbo engine and get 200hp out of one rotor, most twin rotors can obtain 400hp according to the Internet and apart from the engine I saw on the rotaryeng  site I have not located another and at Paul's suggestion I have e-mailed Richard Sohn hoping he might answer some questions for me.

The intent of my story is to obtain options that I can consider , possibly split the engineering process between one or more qualified people and then bring the project together  under the most appropriate person to do the final stress calculations balancing , ground resonance effects and the engine rotor resonance , if someone knows the rotational inertia it will save me possibly pulling an engine apart to measure everything depending on the decisions I make which will have to be made by January to fit in with my current planning . I am open to constructive criticism and advice so feel free to make comment wherever it might be helpful or beneficial to the project, just like the “bridge builder” it is not just for me but for the people who come behind.

Kind regards

And best wishes

George

Hi George!: you've been very kind in your response to my note, but I missed completely the facts, it's not you designing an helicopter from zero yourself and alone, but building an already proven project; as the goal in my comment was making some mild mental pressure towards consulting experts, and taking the things slowly and with lots of wisdom, you've show you're already doing this by your response, thus, I just want pointing that I offer you my best wishes for success in constructing and flying a homebuilt helicopter.

By the way: the Spanish prototypes I cited, all them flew successfully, just the whole program was discontinued because budgetary reasons, equal as the British politician Shackleton? send to wreckage the TSR2, or something like, supersonic bomber airplane project. Salut

Jose Gros-Aymerich Madrid, Spain



Please check out the Schweitzer (Hughes 269 & 300) which have had the main rotor gearbox driven by 8 V belts since 1960.  The belt drive also functions as the clutch between the engine and the trans.  There is a movable idler pulley, which was originally hand operated and later electrified, that takes up the belt slack when it is time to bring the main and tail rotor up to speed.  To the best of my knowledge there has never been a failure with this drive.  The helicopter will fly with only 3 of the 8 belts.  It also provides good dampening between the Lycoming 4 cyl. and the trans.  There is also a quill shaft between the engine and the drive pulley which provides addition torsion isolation.  The quill shaft has crowned spines at either end which allows the soft mounted engine to move around some.  All in all, it is a rugged system with hundreds of thousands of hours (including a few years as the military's primary trainer) and no real failures.

A belt drive for the tail rotor (Scorpion) is probably not a good idea.

Gary Knutson