Mr Cox

I tached my Conquest .15 RC today. With the stock RC head (regular glow plug) and stock muffler I get about 16600rpm on an APC 8x4 (10% nitro, 20% all castor).
It easily the strongest .15 RC engine I have...

aspeed

It was my strongest too, until I got the Fora.Even beat my old Rossi, the unpiped one anyway.Too bad Mecoa doesn't make them any more, or sell parts. Someone else should maybe take over the production if they can't do it any more.Maybe Cox International should think about it. The Conquest was easily the best motor ever made by Cox. I tested a whole bunch of .15's and listed the rpm's in this thread somewhere, I used a 7-5" MA prop because I found that size best for what I like to do. It went 19,500 rpm.

Mr Cox

Cox International had some spare piston and liner sets a while ago, so I bought two sets for my two engines, should that should last a while. Mecoa might have the rights to make new parts though, jst hope they will do it or sell the right to someone who will...

I haven't tried a 7x5 prop yet, the engine should like it better, but an 8x4 is a good test for any .15 sports engine.

earlwb

The Cox Conquest .15 is a great engine, but you might want to be careful trying to get the most out of it. The connecting rod is its Achilles Heal as it tended to fail when RPMs exceeded 22,000 RPMs. The engine could run and produce power up to 27,500 RPMs too. The early cast aluminum and later machined aluminum rod without a bronze bushing weren't intended to hold up to more than average sport flying, so you might want to get as better rod if you want to run the engine more strongly. Some guys suggest replacing those rods in any case as they are more weak.  K&B and some others made special connecting rods for the engine for racing or competition purposes that work much better of course.

I think nowadays the special European made competition 2.5cc engines can outperform the old Cox engine by a considerable margin. But the Cox engine is still something of a legend anyway.

aspeed

It is certainly the best Cox ever made. At the time, it was easily the best one available (1978 or so)  I wouldn't pay a lot to get a used one just for flying.  I would , and did, get something more modern like a Fora where parts are obtainable.  Too bad Cox International can't get a hold of the molds and tooling from MECOA.  I am afraid to really use mine because of the parts availability. MECOA seems to have given up on the Conquest.

earlwb

I think it was a bit more convoluted than that. At the time K&B bought the rights to the Cox .15 and maybe the .21 and .40 engines that the Cox ownershad decided to sell off. I remember K&B as I was using K&B .15 engine for racing at the time and after K&B got the Cox .15 they quickly quit making their own .15's and just started selling the Cox .15 instead. K&B later went out of business and MECOA bought it all up.

But later Cox went out of business and the Cox company was broken up into pieces. I think one piece in the USA still sells some electric planes, etc. But the engines all went to the Cox International business instead.

I suspect MECOA isn't all that interested in manufacturing the engines as much as seeing how many engines they can make from the parts leftover and if they need to make parts to complete those engines or not. They seem to sell out of something and never make them again. But maybe with the wars overseas winding down and the government cutbacks, they might get more motivated to make model engines again. Hard to say though. I think at present MECOA is making parts for various government contracts and those tend to be the money makers so model engines get pushed back to be made later as time permits.

aspeed

They aren't much help to the hobby if they just quit manufacturing them completely.  Just try to pawn off the fire sale aquisitions.  Maybe they should let someone else try.  It is hard  to find competent machinists I guess.  I know I would rather make stuff with a .005" tolerance than .0001".

earlwb

I forgot to clarify the connecting rods. They made the first ones using a cast rod, and later a machined rod with a aluminum bushing instead of bronze. Later K&B and MECOA both made a number of racing rods too. The machined out of bar stock rod didn't have a bronze bushing either. They probably used a 7xxx alloy for the rod and it didn't really need a bushing.