RC-Hangout

So I heard an interview with the AleeS design guy on RC Heli Nation from the their part 1 of OHB coverage. Did some googling and came up with this:

From: http://www.facebook.com/ALeeSHelicopter ... 3340529110

ALEES "TDD" UN-MASKED
WHAT IS THE ALEES TORQUE DAMPEN DRIVE?
AleeS "TDD" (Torque Dampen Drive)
Innovation by AleeS. Patent Pending.
Ready for today's and future high power systems
Features and Benefits
• Tail torque dampening device embedded in all new auto-rotation hub;
• Light-weight and fully serviceable 7075-T6 hub construction with ultra hard dampers, stainless steel shaft and brass bushing supports;
• Isolates the excess torque produced by the power surge of today's high power systems (gov or un-gov);
• Enables logical and balanced gyro tuning of the tail stop gain (crisp stop vs. over stop);
• Improved tail transmission efficiency over all speed ranges;
• Reduces tail drive gear wear for the complete tail transmission;
• Fail safe system that lowers chance of complete tail gear failure caused accidental tail blade contact with ground and ensures safer landing; and
• Enhances overall flight performance

There are some pics there too, so check it out.

I posted in the facebook thread what my translation of what this "actually" is (the post and the guy in the interview were remarkably unable to actually say directly what this Torque Dampened Drive is):

Looks like it allows the tail drive gear to soft-couple to the main shaft. The Jesus bolt is replaced by a threaded pin, around either end of the pin is a damper and a cap screw. The damper will absorb some of the thrash that tail drivetrains are subjected to on hard torque changes, high gain settings (gov or tail gain), etc. Will help prevent tail gears from developing slop over time. Kind of doubt it would do much to save gears in a tail blade strike with the ground, though. As for "do belt drives" have this naturally, mostly yes. They have some small amount of give and will jump teeth instead of strip, so they have some of the benefits (and more) of this kind of system. But they do not necessarily offer the same level of coupled dampening this does. For high frequency vibrations and shocks this system may well buffer and smooth things out better than a belt drive, which can be quite rigid and transmit gov/tail over-gain trashing through the drivetrain.

So, anyone else hear about this or see anything about it?

It's an interesting concept. Similar to what is done on some shaft drive mechanisms on trucks, motorcycles and luxury/sports cars, though they usually accomplish it with a dampening rubber interface between the drive shaft and a slave/driven shaft. Often it is little more than a rubber disc bolted between two shafts. Sometimes integrated into a u-joint or CV joint. It allows spikes from either the driven or driving side to be softened before being transmitted down the line, reducing wear and tear on gear interfaces and other mechanics.

So is this desirable in a RC heli? Worth the couple extra parts and hassle during assembly?

It certainly sounds like an interesting concept, but isn't it just more parts to worry about going wrong, like those TDO dampeners failing, then do you have a worse situation on your hands with play in main shaft to main bearing.. And it wouldn't be needed in a belt drive setup as the belt itself acts as a form of dampener, as rightly said the belt would skip teeth if necessary.. Not sure that concept does enough tbh.. But who am I... Lol

You need something that will prevent losing teeth in the gears on a TT tail wouldn't you, this won't do that.

I dont really now enough about helis to make any justifiable comments but there's my pennies worth to start it off...

I do understand it there to dampen torque changes from motor to tail though

They were talking about this on the OHB RCHN show.
Seems like a good idea to save on gear wear.

Not convinced:( more parts more problems. Looks like they have invented a shock loading and gear box backlash system in one. Would be good to see in action:)

I heard it too. Yes he did tap dance around what it was. I don't think he is ready for a full disclosure yet. Sounded like a good thing. He also stated it adds very few parts and weight. Not sure if this was a torque tube thing or a swash thing.

He's filed a patent application. You don't get too much more full disclosure than that. In fact that is the point of a patent.

It's neither, from the looks of it. The pics and diagrams indicate it is a lower jesus bolt replacement. Instead of rigidly attaching the gear/hub to the mainshaft it instead puts a rod through two rubber damper sleeves, one sleeve in either side of the gear. Held together by a cap screw and washer in each end of the pin. It's more or less the same kind of arrangement you have on the spindles of the main and some tail rotor hubs. Except in this case instead of absorbing flapping forces of the rotor, it is absorbing shocks to/from the tail drive train.

It will probably save some wear and tear of the tail gear system (from the tail drive gear on the mainshaft though the umbrella gears at the rear), saving them from some of the jitter induced damage that ends up requiring replacement after a year or two of hard use or too-high a gain setting on gov or gyro. But I'm not sure it helps beyond that. And I expect it may mask a certain level of too high a gov gain setting, since one of the first signs of it is usually felt/heard in the tail. But he's claiming it can help simplify and improve gyro gain setup, particularly getting a good start/stop response. This kind of shock buffering should let a user crank up differential gain somewhat, get a clean start/stop, and help reduce the jitter that often results from the drive train getting impulse loaded and the gear meshes all loading up in sequence and then back lashing chaotically, etc.

I didn't know much beyond what was talked about on the podcast. Will see how it does. I am sure alees fans will be jumping on this quick.