J D 8 - Moderator

On a day when the sun is overhead the models shadow will be on the strip.

Hi Simon, Just another tip, if you find new bearing is a bit loose in case and likely to spin, some bearing lock fluid Locktite 641 or similar will keep it in place. Cheers, John.

The ASP91 has its prop driver kept in place by a tapered split collet, the rear of it nests against the inner race of front bearing and when prop is tightened the collet holds both the driver and the crank in place.[no shim] The only end float would be as a result of movement in bearing. Just Engines have a good diagram of the engine.

Hello Rich, Yes the Cox Medallion 09 has that stub as did a Medallion 15 I once had. It is a connection to pressurize a fuel tank. I have heard it can make needle setting rather critical but can not be sure as I have never tried it. To use it one has to drill out all the way into the crank case, engine has to be stripped to do this and clear any swarf.

Following the Cox on the test stand PAW 80 I picked up a few years ago SH, has extended compression screw and a very nice prop shaft extender knurled both sides for grip. Fired after a few flips and ran like a good one as soon as some gunge in ventury cleared. Throttles well too. Been on my "must make something for it to fly in too long". A little gem.😁

A later version was made with with a barrel restrictor linked to a ventury throttle. Don't know if this was any better.

Cox Medallion 09. I have run many a Cox engine just fine, my own and friends but not this one. Purchased many moons ago to go on a wing seat power pod for Flair Fledgling glider. Cox at this time 80's/90's finally started to think of limiting the wonderful/horrendous depending on your point of view exhaust note. Came with an exhaust collector ring, muffler, supposed throttle which is just an exhaust restrictor. Just nowhere near enough power for glider[even without muffler] where as PAW of same size hauled it up and away. The collector did work well as a muffler provided the black spring clip you can see in pic was in place covering the outlet springing out just enough to release the exhaust pulse each stroke. However this just killed the power. A circlip at the base of collector linked to a rod to rotate it and restrict the exhaust. As a throttle it is rubbish, will reduce revs some or act as a cut out. In the test stand today, had in the end use electric starter, my finger got tired/bored.😁 Next engine on the stand a little gem but that is for the other thread.

Hi Andy, Like you I just come in on latest posts. Just tried switching to "Forums" and it went there with no issues. I am no computer expert so can not help much but will see if others can help. John.

One thing I have noticed down on the club field is that while the standard size WOT4 and Ugly Stick are both good flyers when it comes to the up sized versions the WOT XL is also a good flyer but the Giant Stick is shall we say a rather "staid" in my opinion and as for the 100" version it's yuk.

If you can find one the May2012 RCM&E issue has a very Good feature "Down to earth" by David Ashby giving many good tips on landing your model.

On a great flying day last Friday a club members model stopped responding to control and went AWOL in an area of deep high scrub [ jungle] that resisted attempts to enter it on foot so on Sunday using my Land Rover we were able to push even deeper into chest high growth and by standing on the roof were eventually able to spot a wing tip. Even then it took some effort to get to the model and return to civilization.

Better design in that there are no threads in the head to ruin in the first place, a longer bolt with double lock nut can be fitted to hold clamp and/or wire it up as ED notes above [This comment is for later vertical plug Lasers not the ones where grub screws do the holding]

I have to say that the design of threads in the head that most model 4 strokes use is a poor one. [Laser have a better design of a pipe that slips in with a seal and held in place with a clamp.] The exhaust only has to come loose once and if not caught quickly the threaded area soon wears and getting the exhaust to remain tight gets difficult. Doing as Paul above suggests will work can work for some engines. I have tried various compounds on the threads but none work for very long. On an old Enya 90 I fitted a remote muffler, this takes the strain off the header pipe having first heated said pipe red hot and expanded it a tad with a mandrel to once again have a tight fit. Flexi stainless pipe joins the two.

Very much agree with John above. I like to get scale/semiscale and trainer type power models to a set up that with full power they tend to climb, fly level at cruising and be in a steady decent with some power still on while on the way to a landing, no messing about with switching in/out this or that on the way to touchdown. This is mostly achieved by getting CG and basic trim right. On some types thrust line may need adjustment. Some like heavy warbirds, precision aerobatic types, gliders, and things with odd thrust lines do have different needs though.

Top one likely a fake.