Build a synchronized tandem rotor - I GOT IT!!!

Frank,

Not a bad idea.  I used some coiled springs, like in a ball point pin but more flexible to make 45 degree turns for an Apache tail rotor.  I think in this case some direct gearing would work really well.  I used the gears on HO slot cars to make the 90 degree gearbox on the Apache and connect to the main rotor drive.  Never finished it but it worked.  Camera is "inop" so can't take any digitals to post.  Maybe I can resort to some drawing later! 

How about using a beveled gear arrangement?

I didn't check the sizes but you can get an idea of what they would look like here:

 http://www.smallparts.com/products/descriptions/gbb%2Ecfm

Jonathan Primm

Youngsville,LA

Jonathan,

I think you are on to something!  That would work well I think. 

Melgyver wrote:

Jonathan, I think you are on to something!  That would work well I think.

Well, it was Frank who came up with the idea, I was just thinking of a way to construct a mechanism without having to use a flex shaft... Using these, it may be possible to get away with something simple like plastic, aluminum, or brass rods/tubing.

BTW are you going to be in Lake Charles this weekend?

Im headed to Lake Charles, see you guys there!

David

J.H. Primm wrote:

Melgyver wrote: Jonathan, I think you are on to something!  That would work well I think.  Well, it was Frank who came up with the idea, I was just thinking of a way to construct a mechanism without having to use a flex shaft... Using these, it may be possible to get away with something simple like plastic, aluminum, or brass rods/tubing.

No, no... I like reading the input and welcome all the ideas it spawns!    

I think building a working drive train wouldn't require much, except a piece of aluminum tubing (or even a plastic rod), and build/find 4 interlocking gears.    Providing each gear is the same size and the rotor heads are in position when connected, I think the configuration below could work....

I looked at the 1/48 kit pieces, and there would be room enough to locate the aft gearbox inside the buldge on the top/aft kit ceiling piece.    The top of the enclosure would act as the lower brace for the aft rotor shaft, so the bottom would have to be detailed up so the gear won't be recognized by a viewer.   

 Thanks, and ya'll have fun at Lake Charles!

  Frank 

Love it when a "plan" comes together!  Who will be the first to give it a try? 

Jonathan,

Yes, I plan to go to the Show in Lake Charles! 

Melgyver wrote:

I used some coiled springs, like in a ball point pin but more flexible to make 45 degree turns for an Apache tail rotor.

Mel,

Thank you for planting the idea about using "springs"!      I made a test stand of sorts and connected the drive shafts with three ball point pen coilded springs, and it worked flawlessly!!     The trick, given the length of the shafts and weight of the rotors, is lubrication, especially where the rain shields come in contact with the pylons, and at each point where the drive shaft passes through a support brace.       As long as each joint is slick, and each spring/shaft connection is tight, the rotors will be synchronized!

Thanks again all, I think this is the way I will hook up the rotor system on this kit.      If someone wanted to motorize this configuration, the DRIVE gear should be installed at the shaft juncture box in the aft pylon.

Take care,

Frank

Frank,

I used the next size up of brass tubing to make a "bushing" to put in the shaft support and lubricated it with grease.  Glad my "expertise" is of some value!   I found some nylon "differential" gears at a local Hobby Shop used for R/C Cars and Trucks that show some promise.  Ony thing I will have to drill out holes for the small gears to fit on the shaft and the larger ones could easily attach to the main rotor shafts.  They stocked a variety of small gears that could be used to futher motorize the whole drive train.  The differential kit was only $3.  Sorry I haven't the time to draw out the gears.  Also my digital camera is "history"!

 I must say, I always enjoy the intelligent discussions you guys have.  I always say, two heads are better than one.  Sit back and watch the imagination become reality.  Very educational.  I dig the drawings!!!  Just like patent drawings.

I just never had the guts to do what you guys do.  I've thought about it and pondered as to how to go about it; but that's it.  

John 

Hope to be dropping by more this summer.  Been hanging out over at ARC lately. More civilian modeling folks there.  LOL! 

Melgyver wrote:

Frank, I used the next size up of brass tubing to make a "bushing" to put in the shaft support and lubricated it with grease.  Glad my "expertise" is of some value!   I found some nylon "differential" gears at a local Hobby Shop used for R/C Cars and Trucks that show some promise.  Ony thing I will have to drill out holes for the small gears to fit on the shaft and the larger ones could easily attach to the main rotor shafts.  They stocked a variety of small gears that could be used to futher motorize the whole drive train.  The differential kit was only $3.  Sorry I haven't the time to draw out the gears.  Also my digital camera is "history"!

Mel;

Which shop was that? Was it in Lafayette?

Jonathan Primm

Big Boys Toys on Fue Follet has a lot of that kind of stuff........I maystock up next time Im in there to try this on one of my Phrogs.......

david

Jonathan,

I picked it up at Big Boy's Toys off Kaliste Saloom.

Mel;

Thanks I go by there all the time...I know exactly where it is.

Jonathan

Melgyver wrote:

Jonathan, I picked it up at Big Boy's Toys off Kaliste Saloom.

Hmmm... how about a part number or name of the item, 'cause I'd like to get me one too!

Take care,

Frank

Frank,

I'm "feet wet" right now.  I'll check when I get back home and get the Manufacturer and part number of the "kit".  Since the parts are nylon I expect it to be "tricky" to drill a true centered hole in the small bevel gear for a shaft.

Frank,

The parts kit I picked up a couple weeks ago is by TeamLosi.  Transmission Gear Bag, Mini T, LOSB1066, Differential Gear Bag.  The sicker with the same part number calls it Transmission, go figure.  www.teamlosi.com

Melgyver wrote:

Frank, The parts kit I picked up a couple weeks ago is by TeamLosi.  Transmission Gear Bag, Mini T, LOSB1066, Differential Gear Bag.  The sicker with the same part number calls it Transmission, go figure.  www.teamlosi.com

Thanks Mel,

    I'll go check it out, and probably get me some of them!   There's all kinds of possibilities lingering there, thanks!

Take care,

Frank