Dollies and classification?

[Andrew Tinsley]

Hello Everyone,
A little help needed. In the vintage speed classification for US models can someone tell me the engine size for each class from 1/2A to D? Sometimes I see reference to class C as 10cc as well as class D being 10cc. I am not sure if the classifications have changed overtime or if the US and UK classes are different.
Second question, maybe not so simple, is about dollies, are there any standard designs, or does everyone do their own thing? Are there any sources of information about the design and construction of said dollies? Just to whet my appetite are the wheels all parallel or is there an advantage in having the design set up to run in a circle (somewhat larger radius than the line length!!)? Finally I see various references to different type s of model restraints, any one type better than the others?

Thanks for any help you can give me,

Andrew.

[don Burke]

Here's a link.

http://www.clspeed.com/node/7

[Bob Heywood]

Classes and engine size limits have changed a few times for AMA C/L Speed.

Very early on, circa late 1940s, there were six engine size classes, Class 1 thru Class 6. That soon changed to the familiar letter designation. At that point there was 1/2 A for .049, A for .19, B for .29, C for .49, and D for .65.

The next change dropped the .49 engines and Class D. Class C then was for .65. A was then lowered to .15. That happened sometime in the mid to late 1950s.

In the 1970s or so there was a short lived Junior only class for .40 engines that was given the C designation and the .65 engines went back to Class D. When the Junior class folded D was kept for the .65 engines.

The NASS now has an event for the .40 engine that uses Class C.

Dollies: There is no standard. There are two basic forms. One is a mousetrap that physically holds the plane by clamping down the wings until the dolly / plane combination lifts off a bit and a dragging trip wire releases the wing hold downs and lets the model fly away. The other is a simple lift off type that acts like a cradle and allows the plane to fly away on its own. Tracking is usually set straight ahead. Several people have used metal or other low traction wheels that will allow the dolly to skid sideways around the circle. A big word of caution! Some early dolly drawings show Trexler Air Wheels being used. Do Not under any circumstances follow that lead. Those wheels simply don't work. Except for the wheels the dolly shown on the Dizzy Boy plan is pretty generic.

[Motorman]

I like the tail hook dolly. Seen too many mouse trap dollies get stuck, lifted and flung. Definitely steer the thing to the outside of the circle.


MM

[Bob Heywood]

Here is a link showing a winglock "mousetrap" type dolly. The one shown is for an F2A size model but it gives you the idea. Just scale up or down for different class models.

http://www.f2aspeed.org/node/13

[Bob Heywood]

I Googled "C/L Speed Dolly" for these.

Note the tape on the wheels for the one with the yellow plane. That is done to let the dolly skid easily.

The tail lock mentioned by Motorman is a variation of the basic lift off type. A couple of hooks trap the trailing edge of the stab to keep the plane from tipping up on its nose. The plane then simply flies itself out of the dolly.

[Bob Heywood]

Interesting link...

http://www.angelfire.com/fl/yspeed/

[Andrew Tinsley]

Hi Bob,
Thanks very much indeed for sorting out the contorted classification system and its changes over the years. No wonder I was confused! Thanks also for the effort in sorting out some examples of dollies and their operation. I did Google the term, but forgot to put in C/L, I may get myself sorted soon when looking up info on the net!
There is plenty of info there in your refs to get a good feel for subject. One last query what is the class for 10cc in US vintage speed right now is it C or D?

Thanks for all your help, it is much appreciated,


Andrew.
 

[Bob Heywood]

Andrew,

It looks like 1964 is the cut-off for Vintage Speed. That would make 10cc / .65 engines Class C.

Good Luck...!

Clockwise Forever,

Bob

[Motorman]

There's also a cut off at 1954 for 8cc (.49) in C speed.

[Andrew Tinsley]

Thanks guys,
And I thought that life was simple!

Andrew.

[Steve Helmick]

In AMA, I used a .65 in "C" speed in the late '60's, but sometime later it was changed to "D" with same engine size. Never really understood why, but I wasn't flying speed anymore, so didn't pay much attention. There was some thought that Juniors couldn't hold onto a .65 going 200 mph, so I suppose that was it. I'm not sure if they made "Junior C" for .40's, but probably. I don't think we ever used less than .65 maximum in our biggest class, so no 10cc. If my math doesn't fail me, .65's would be 10.8cc? Maybe this was a return to the early '50's classes, but there wasn't anything between B and D until recently, when the NW rules for C speed was promoted and accepted for .40's. This is a cool event, IMO, with mini-pipes and either monoline or 2-line. The real problem with all the .29> speed event is that there are no suitable racing engines made anymore, or at least not easily available, like in the '60's.

I always used "lift-off" dollies, 3 wheelers, of my own design. They evolved a bit, and worked quite well. I did make one "pin dolly", and it also worked ok, but I didn't really like it. I made them track straight or slightly out, but I feel the real trick was to set the model on the dolly and drag it sideways (on asphalt or concrete) with a short piece of line. If this pull makes it yaw in, it's gonna be exciting at best. If it yaws, shorten the rear or change the wheel/tire so that it will slide...or move the front wheels forward. Like everything else, it's the CG that is your reference point. Anyway, it worked for me, back in the dim and distant past. I never read or heard of anybody else doing this, but did see some tires wrapped with vinyl electrical tape to make them slide sideways more easily. Often inside front, but also rear.  Too much rear traction was really dangerous, hence the short rear and small tire.  Steve

[Andrew Tinsley]

Thanks for that Steve, some good nuggets to digest. Simple but very pertinent advice. Most of my dollies were scrounged or borrowed so I never did work it out for myself.

Thanks,

Andrew.