How was this Twin 049 made?

RknRusty wrote:Ahrma_581, welcome to the forums. That guy in your avie looks like Reverend Jim Ignatowski.

http://www.cbs8.com/Global/story.asp?S=13209288

RknRusty wrote:I sent him this question:
In the picture, one piston looks to be up while the other is down. How can it pull an intake vacuum or compress the fuel/air charge in the crankcase with the pistons working against each other? Am I missing something? Any chance you could take off the tank and show a picture of the rotating assembly? And the venturi too.
Interesting engine. Thanks,
Rusty

His answer, as we know was:
Dear rknrusty,

sorry, i am not going to take the engine apart. i do not know auything else about it. what you see is what you are purchasing.
- widow315

WingingIt74 wrote:

RknRusty wrote:Ahrma_581, welcome to the forums. That guy in your avie looks like Reverend Jim Ignatowski.

http://www.cbs8.com/Global/story.asp?S=13209288

I liked it better when I thought it was Reverend Jim.

WingingIt74 wrote:

RknRusty wrote:Ahrma_581, welcome to the forums. That guy in your avie looks like Reverend Jim Ignatowski.

http://www.cbs8.com/Global/story.asp?S=13209288

That's funny, I'd forgotten where it came from. Just so we're clear, I'm neither the father nor the son in that article!!!

ahrma_581 wrote:

WingingIt74 wrote:

RknRusty wrote:Ahrma_581, welcome to the forums. That guy in your avie looks like Reverend Jim Ignatowski.

http://www.cbs8.com/Global/story.asp?S=13209288

That's funny, I'd forgotten where it came from. Just so we're clear, I'm neither the father nor the son in that article!!!

That's a car crankcase on the twin...

Big Al wrote:

WingingIt74 wrote:More precisely the crank. I can see how the case was made. I assume it just has a longer crank pin to accommodate both pistons? Ideally you would want them something like 90º from each other?

It's sprouted my imagination on trying to figure out and maybe building one.


http://www.ebay.com/itm/260982078736?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_500wt_1156

Several years ago that same engine (or one identical to it) was on eBay. At the time I also wondered if it could be a runner. I did a layout using stock Cox parts with thoughts of duplicating it and at first glance it looked like it might be possible by using a silver soldered crank assy. But alas, (see sketch) there was a serious fly in that ointment.

Possible if you could do the second part as a screw on.

Many times the second web is pressed on --- this is fairly common on multi-cylinder 2 stroke engines with needle bearings on the lower end of the rod.

But, in any case, I agree that the piston postions are problematic. To get the necessary crankcase vacuum and compression, the pistons should be mounted on the crank 180 degrees apart. Induction could be either reed or rotary disk. The picture clearly shows one exhaust port open and the second port covered by the piston. It may be that one of the rods or the rear web has snapped and only one piston functions.

Rotary disk induction may be more appropriate since a reed valve would require that the second throw be fully floating and unsupported. A rotary valve would add some rotational drag, but would support the rear rod journal.

andrew

Twins coming out of the woodwork At least this seller is truthful in that they said it doesn't run.

http://www.ebay.com/itm/UNIQUE-COX-TWIN-CYLINDER-049-MODEL-AIRPLANE-ENGINE-/230767275537?pt=Radio_Control_Parts_Accessories&hash=item35bacd2e11#ht_4157wt_1224

The crankcase on that one was done well.

cribbs74 wrote:The crankcase on that one was done well.

Not sure if it's any better or not...


I guess you could do a threaded insert, can't tell with this one.

http://community-2.webtv.net/injunnut/UniqueSMALLModel/

Nice engines in that link, but unfortunately the link in the article is dead. I would really like to see how he had made the crank.
Regards
Thomas

does anyone know were one does get a working engine like that

i need one for a boat i am building

They are all custom engines. Opposing cylinders in such a small crank case do not work.

to bad

If you want a twin that runs look for a geared twin such as the Selena products geared twin. They pop up on ebay from time to time.

Jason_WI wrote:If you want a twin that runs look for a geared twin such as the Selena products geared twin. They pop up on ebay from time to time.

I do not understand the point of this engine. It looks really heavy, and if I wanted something with twice the power of an .049 I would buy a .09 engine. In fact, I would probably buy a .15 engine. The medallion .15 I have is probably the best engine I have used. This seems like a lot of work, for something that is nothing more than a curio. Is there some competition that uses this engine, that I am not aware of? Thanks, Andy

anm2 wrote:This seems like a lot of work, for something that is nothing more than a curio.  Is there some competition that uses this engine, that I am not aware of?  Thanks,  Andy

For some folks, it's the trip getting there, not the end of the journey.

WingingIt74 wrote:It's not the only one built like that. Which kinda makes me curious.  This one is also on ebay right now, just not as pretty.


http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130667422142&fromMakeTrack=true#ht_500wt_1108

Notice that with this engine there is no offset between the cylinders, as there is with the 1st one (top). I can't see how this one will work, but the 1st one has the offset presumably to accommodate the 180° crankshaft.

Aw man, what a waste of a 128tpi NV.