Simple Power Transmission Unit for Intermeshing and Interleaving Rotorcraft

[Dave_Jackson]

This thread is just to put the following invention into the public domain; so that anyone may use it.
http://www.UniCopter.com/1509.html

Criticisms requested.

Dave J.

[Matthew Parsons]

I'd say that has some merit. Fairly simple, lightweight. Because the Ball Wheels are not coplanar, inward lateral loads will try to move the worm rather than compress it. This means the bearings and housing will have to be beefed up.

Another concern is when manoeuvring you will have assymetric torque requirements on each rotor. This could result in very large forces being applied to the worm. The worst case for this is in autorotation with an aggressive roll rate, the rotors will want to turn at different speeds, but that worm will have to keep them in sync.

Would it be an improvement to have this as a driving mechanism but still have a conventional gear between the rotor masts for synchronisation?

Just my $.02

[Dave_Jackson]

Matthew said;

Would it be an improvement to have this as a driving mechanism but still have a conventional gear between the rotor masts for synchronization?

Thanks for your valid comments and specifically the concern about synchronization.

An idea for this has been added to the web page; here [http://www.unicopter.com/1509.html#P...e_Improvements]. Its your idea and it look quite simple, only requiring 2 more gears.

Thanks.

Dave

[rotorque]

Hi Dave,

It's is funny how this sort of thing happens.... Believe it or not I am in the process of building a similar sort of design. I am using a 'coil' drive system which in essence is a form of worm drive. The design uses intermeshing rotors set at 25 degrees coming off a set of drive wheels. These drive drive wheels, powered by the coil, utilise 10 bearing blocks set at 36 degree intervals therefore giving me a 10:1 reduction for my Subaru EJ22 engine.

The beauty of the design is that it does not require a 'gear box' and its associated weight. It accounts for reduction, horizontal to vertical drive and allows the drive wheels and masts to be angled as required. And I have found that it is releatively simple to build.

There is a sprag clutch in the centre of each drive wheel that the mast (shaft) goes through and accounts for auto if/when the engine stops. Synchronisation is provided by two bevel gears at the bottom of each mast (shaft) that are in constant contact.

Yaw control is by an electro-magnetic brake on each mast that provides for torque loading. A 'crossover' switch is used when the collective is at a set position to swap the torque loading (which brake to apply) between the masts during low power/auto.

I have CAD drawings etc if your interested...... In fact I got alot of info regarding intermeshing designs off your web page, but never saw this little tid bit.

Cheers

[Dave_Jackson]

Hi rotorque,

Yes, I would appreciate seeing your CAD drawing. If you wish to email it, the address is [email protected]

It must be a very advanced system, because when "coil drive system" was Goggled this page came up
http://www.youth.net/frpg/engineerin...yson-class.htm

Dave

[Graviman]

Dave,

My one puzzlement is why the need for roller bearings, when oil hydrodynamic lubrication between gear teeth is approx 99% efficient? In fact ball/roller bearings actually rely on hydrodynamic lubrication, using oil in place of grease for cooling. Not saying it isn't a neat idea, but it looks potentially expensive to assemble (and machine) - don't forget you will need a return path for bearings to "fall off" the end of the track. If you do use bearings go with case hardened, rather than through hardened, as overload will not cause catastrophic failure - otherwise you will have lots of broken ball bearings from a single event.

Have a look at hypoid offset spiral bevel differential gears, if you want to do some calculations on gear design. Gleason have some useful publications. This will give you a practical feeling for maximum ratios achievable, without affecting autorotation performance.

Mart

[Dave_Jackson]

Mart,

Matthew mentioned his concern about the transmission having sufficient strength. The roller was brought up for consideration because it will handle greater loads than a comparable ball will. However, as you say "it looks potentially expensive to assemble (and machine)"

If balls are used then the transmission might be called 'Goliath', because its going to have big balls.

The spiral bevel gear will not provide sufficient reduction and making it hypoid will increase the sliding friction. To my knowledge, the primary advantage of the hypoid gear is that of lowering the floorboards in cars.

Dave

[rotorque]

Hi Dave,

I will send you some drawings etc tonight.... Aussie time.

I must be a closet trekky

The coil drive is my own design for this application so there isn't any info out there that I know of. Another benefit of the design is that there is no need for oil as all bearing blocks are 'greased for life' and the actual coild drive is a dry system. The drive should work out to be half the weight of a gear box (if that) but of course using an intermeshing design eats into any gains I have made with the drive system.

I am yet to do the load calculations (maybe you can help me here ?) but I believe the coil drive is only suited for powers up to 120 KW.

Chat soon.....