Ahh, crud... I'm getting a new idea... and you know what that means...

Modeling Subjects Aircraft
1

Basically this idea can be summed up with a simple math problem. It goes like this:

[image]http://www.model-news.com/air/02_72/tu95h/box.jpg[/image]

[image]http://www.allelectronics.com/images/gold/thumb/DCM-166.jpg[/image]

=

Total working contra-prop insanity!!!

Now, before anyone starts dialing the nearest institution, here’s my reasoning behind this. First of all, I like to push the envelope, and believe it or not I’ve gotten a working contra-prop gearbox before. There will be, however, a few hurdles to overcome-

-Space. I don’t have a place to put it right now.
-Refineing the contra-prop mechanism. It’ll more than likely involve machineing most parts from metal, something (at this point) I have no access to.
-Cash. Perhaps the largest hurdle to overcome is that $106 price tag on the Trumpeter kit [B)].

Becuase of this, right now this is just a dream. I don’t plan to start on anything for quite a while. But it’s a dream I will be pursuing for the forseeable future. (On the side of other projects, of course.) C’mon, how cool would it be to see working contra-props on a 1/72 Tu-95 Bear? I think it’d be awsome!!

And no, I’m not crazy. Don’t look at me like that! I swear I’m not! Really, I’m not!

(I’m not crazy.)

2

Sure you are, admit it. You’re crazier than this fella…

Hey man, have fun!!

Fade to Black…

3

Admit it your crazy…Crazy like a Fox!!![:D]

4

There is a mighty fine line between insanity and genius. It’s all in the eye of the beholder.

Darwin, O.F. [alien]

5

You’re not crazy, just a dreamer, but then where would we all be without the dreamers?

I think it’s a great idea, and it would be an incredible thing to bring to the modeling scene. You say you have already done the contra thing before and I would like to see how you engineered it. It would have so many applications in the modeling world.

Go for it Bro…we’re all behind you.

stinger

6

Dream projects is a good thing, for me it´s a 1/72 747 with a space shuttle on top. Some day…

That looks like a huge kit, and an excellent ideea. Isn´t lack of shelve space (and cash of course) a [censored]. I´ve got several kits that I can´t build because I can´t put them anywhere.

Good luck and keep us posted /Johan

7

Well, persuing dreams is a good thing. Wish you well in completing this one.

Regards, Rick

8

Nothing wrong with being a dreamer, hope to see your project someday

9

It sounds like a really cool idea…I for one can’t wait to see it work… you never know…this could also lead to working Helo head and tail rotors.Just don’t keep all the good secrets to yourself !!! Good luck !!

10

Go for it… it would definately be a sight to behold… a real attention grabber.

11

Somthing you might look into is one of the old Aurora Navy VTOL turboprop fighters (think it was the Lockheed version). When the prop system was assembled, it would counterrotate. I’m taking this off the top of my head (been a really long time since I built the kit) but I remember that the front prop had the shaft on it with the rear prop free to spin on the shaft. Between the two props were two (three?) spur gears which fitted into a track on each prop (on the rear of the front prop and the front of the rear prop). My problem is that I can’t remember how the gears were secured in place and still rotate. If you had a set of instructions from the origional kit it probably wouldn’t be to hard to build the same thing in 1/72 scale. Realizing the cost and difficulty in finding that particular kit, I would see if I could locate someone who has the kit (or a copy of the instructions) and see if they would make a copyof them for you. I would put a request in the References section of the forum and see what happens.

PS. - I believe that FSM ran an article on the Aurora kit in their Classic Kit series several years back. Maybe one of the Editers could help you.

12

Hey Lucien, does the contrat-roting-setup include removing the motorshaft, replacing it with a hollow one, and pushing a second one in that hollow tube ?
I’ve seen something like that in torpedoes for an R/C boat.

13

There’s been a bunch of talk lately about making working contra-props. The tube-in-a-tube idea is the easy part. The hard part is getting the gearing down so it works, and keeping friction down so can work with most electric motors. My verson used an offset prop, gears, and a belt. Unfortunately, friction on this is a - well, it’s not good. It won’t work.

qmiester- I know exactly what you’re talking about, and it’s most likely the avenue I’ll be pursuing. It has two discs with a couple ‘idler’ gears to change direction. The most difficult aspect of this arrangement is mounting it all, keeping them lined up, and freely spinning. Plus it can be pretty small, which is good.

Yes, I’ve put some thought into this. But, like I said, I’ll work on it, and keep everybody posted.

14

use petroleum Jelly to reduce friction

15

Here is the setup as I saw it for the torpedo…

Blue = Hollow shaft
Black=axle
Green and Purple are the contra-rotating props
Red are pinions

Sorry for the crude scetch, but I didn’t take the time to do it properly

16

And we said you were crazy when you decided to build that Zwilling. Good luck, anyway, you’re going to need it.