Well gentlemen, my boredom with this engine over recent times, came to a sharp end this weekend. No.2 let go on flight no 5 of the weekend. Its a very sobering experience given that just a few flights before, I had commented that the engine was running like a 'sewing machine'. Now its a 'sewing machine' with only 2 running cylinders...lol.
I still dont know what to make of it, but I am reluctant to condemn any of the mods that I have done to it, and considering that this is FrankenSaito, and has been subjected to a ton of abuse over the last year or so. It has one of the new modified piston and cylinder combo's after the last 'incident', its been running a 4-bladed prop, has been flowin in the VERY harsh temperatures of the Dubai summer and has been apart more times than it should have been. Remember I bought this from a guy that had previously had a cylinder failure, that was reparied. I dont believe there is ANYONE that has a an FG60 thats this 'used' before. The weather here has gotten a LOT more acceptable over the past 4 weeks, its gone from 47C to a balmy 27C in a very short time, and this was evident by the fact that the running temps have been 10-20Deg cooler than in the hot summer, and a dive at low revs will always drop the temps significantly in any given flight. Temps have been ideal over the last week or so, and we have done a lot of time on the engine.
I have not had time to do a post mortem yet, we just packed the plane away, and agreed that the airframe of the Seafury, with over 300 flights on it, needs to be replaced. I will pull the engine out this coming week, and am not expecting to find any evidence to suggest anything more than what we already know. In the engines defence, I DID NOT change tuning at all over the last few weeks, and with the temps cooling, I should really have richened it up to allow for the cooler, denser air. This was a mistake on my behalf, and whether it would have changed anything is debatable, but certainly a contender.
Just the same as the last time, the engine was running well, and as it came out of a high speed dive, there was a splutter, and it was on 2-cyl's, no catastrophic event, just kept running and low power glide to a landing...having a look through the cowl, the No.2 had cracks on the mounting 'ears' at the rear of the cylinder....same as most of the failures I have seen.
The question now is what am I going to do? Do i get MORE spares for this or not? With so much time and money invested in it, I do question whether its worth putting more money into it. I di say previously that it was time for this to go to the great big, mantlepiece as a conversation piece....but I also know, I have another FG60 of the older version, and even with the timing mods and experience I have had, I suspect it too, will one day, just let go.
The only way that I could prevent this happening, is to convert the engines to the newer cylinder/piston combo's, and maybe then I might get some useage out of them....
Disappointed is the way I feel right now, as I really would like to have the radial experience, without the Moki price (those things have their problems too) or the UMS experience, which with the pumps and rocker topics....doesnt leave much...
On the UMS topic, the exposed rockers is a bit of a hassle and 'mess', and the addition of a fuel pump does add cost and complexity, but I think might be warranted in the larger of the engines, but the ones under 100cc, would probably run well enough on the walbro pump. The 7-Cyl 90cc is never going to compete with a Saito FG90, with an additional 4-cylinders, there is a LOT of additional parasitic drag and it is never going to output the same amount of power. The 5 Cyl might be a bit closer in power, but still has 2 more compression strokes, parasitic drag and rotating mass, so is not in the same ball park as an FG90, but a little closer. Anyone looking for 'stunt' power by fitting a radial, is looking in the wrong place...there are 2-strokes that will do that.
hpergm, I would say that from all the hassle you went to in the beginning of this thread, with the running in, temperature measurement, tuning by temps, inverting during running in...these engines were VERY far from set and forget. Even Saito have changed the design of the piston/cyl so even they recognised that the engines were not up to snuff. Most of the people on here are not 'isolated' incidents, and I STILL believe, even AFTER my experience, that the ignition mod is a must, and the crankcase mod is a plus....
I have yet to see if anyone with the new engines has experienced the failure...
Now, I am off to cost up the new parts and see whether I move forward with this or not....