Tiny Gas Engine
 

I was just wondering for approximate costs, since MECOA doesn't post the price on their website. Was it less than 4 digits? What's the harm in posting the price unless you got a special "Dealer Price"?

Quoted from Compagnucci's website:That's a 20:1 mix after break-in. That's a bit higher than the average gas 2-stroke, but the average gas 2-stroke doesn't spin at 17,500 RPM.

Roller/needle bearings
 

If anyone in my age bracket can remember the Dooling 61 race car and conlroline speed engine of the late 40's and early 50's you may recall they had roller bearings on the con rod, both ends.
We experimented with 12- 15% Ucon synthetic oil. Still got beaten by the McCoy 60's!

Phil

Tiny Gas Engine
 

MANY years ago there was an OS with a roller bearing rod, maybe an 80, that had a rear intake......Seems like it had 2 glow plugs also...The OPS 30 single has one too..

Finally, a price!!!!!
 

I e-mailed MECOA last week and they finally responded. They explained that they are having e-mail difficulties and are slow to answer. :) :eek:

They said the Compagnucci aero version should be in soon and cost about $280.

Kinda spendy but very novel. I love novelties! Should make a great .40 size fun-fly motor (1.3+hp) and cheap to run and no glow plug and no castor oil and no continuous needle tuning and little clean up and smaller fuel tanks and $1.50/gal. fuel........... :cool:

MECOA (626) 359-9527

If anyone buys one, please let us all know how it runs.

Tiny Gas Engine
 

Just for info:
The term needle bearing does generally refer to roller bearings with long, skinny rollers. I don't know where the term came from, but I expect it has to do with the fact that The Torrington Company, who invented the drawn cup needle bearing (a story in itself), started out as the Excelsior Needle Company, making, you guessed it, sewing machine needles. Their expertise in forming wire, heat treating, etc., led them into making needle rollers, and from there, into the bearing buisness big time.

ball bearings
 

I visited the David-Andersen factory in Norway and talked to the owner Jan David-Andersen. At the time he had in production both a plain bearing and a ball bearing engine. He said the only thing better about the ball bearing engine was that it felt better to the modeler when he flipped the prop!

Re: Finally, a price!!!!!
 

That's better than my response time - I sent three back in April , and still haven't heard from them... :rolleyes:

Bearings
 

Having repaired about a Gazillion chain saws I would just add that many of them have/had needle bearings on the connecting rod (both ends) and ball bearings on each of the shaft ends. So far as I know our needle bearings were not tapered. Some others may have used them, that I don't know.

Tapered roller bearings
 

If a tapered roller bearing were used on a crankshaft, both ends would require it because you need two to oppose each other and be adjustable to have a preload on the bearings. If it were not adjustable for preload the rear bearing would get get hammered unmercifully as slack developed between the bearings.

Roller Bearings
 

In the early 1950's Fox came out with a .29R that was supposed to replace their plain bearing 29X in UC speed. It had roller bearings at the rear of the shaft and ball bearings at the front with a big square front intake. The old plain bearing 29X ran rings around it!

Phil

RE: Tiny Gas Engine
 

Does anyone have ordered and tried this engine? prop size, rpm? I was thinking in buying one.

RE: Tiny Gas Engine
 

I have a Webra SilverLine .61 that has needle bearings on both ends of the rod and a Merco .61 gasoline engine that does not. I have run the Merco many hours on a German synthetic lube with 4 oz of castor added. The rod bearings are as tight as when new.

RE: Tapered roller bearings
 

Hobbsy,
I think you may be incorrect when you say that you would need two taper roller bearings on a crankshaft, - one for the front and one at the rear. - could the crankpin take the bending stress applied by the preload required?

Two taper roller bearings, (opposing each other at the front, and a simple needle roller at the rear, or in the case of a cantilever crank, two at the front only, would be good.
This however, is theory, - In practice, space required, weight and cost would also come into play for production models.

( You may feel free to disagree of course, - but please say why! ;))

RE: ball bearings
 

There would not be a bending load on the rod, the tension would be on the crankshaft between the tapered roller bearings. I only mentioned the fact that it would take two opposed to each other in response to someones suggestion that one could be used for a thrust bearing. It would not be practical anyway since ball bearings do the job so well and the thrust load on them is a small fraction of their capacity.

RE: ball bearings
 

Hobbsy,
I didn't say a bending stress on the rod, I said the crankpin, - caused by the compressive force from the preload on the bearings.

With the two bearings on the front shaft, this won't happen.

(but we are discussing a taper roller at each side of the crankwebs here, - hence the problem).

PS, - I agree that ball bearings do a great job for our application, so what we are discussing is really only theory! ;)

RE: ball bearings
 

There would be no bending force on the crankpin either, the inner race of the tapered bearing would ride in the same spot as the ball bearing does.

RE: ball bearings
 

OK bearing experts-
Please explain why some ruined balls -from a ball race - end up square?
Not joking - seen em a number of times.

RE: ball bearings
 

Dick,
Not a bearing "expert", but I would say that your "square balls" (should I rephrase that?--- naw! :) ), would be caused by the balls locking up and skidding, turning, locking up and skidding, turning, etc etc, till they go roughly square, - no doubt, all caused by dirt and lack of lubrication, - maybe vibration - square?? - well nearly! [8D]

RE: ball bearings
 

Hobbsy,
I think you got me there! - can't win them all! ;)

RE: ball bearings
 

I figured it was some harmonic . the square shape is slightly dished on eaach facet-
Weird

RE: ball bearings
 

Someone, maybe in the bearing industry, will no doubt will come up with a more precise answer!