ORIGINAL: dw_crash
I have had people I know have 'name brand' engines explode. These engines are under high stress. And, it doesn't take much for an explosion. I know of two cases where, one was a grasshopper, and the other some other bug, went into the engine. The impellor was damaged and caused the engine to shred itself. Another case, I was told was a piece of dirt. It plugged the rear bearing oil nozzle. The bearing seized and the engine exploded. All were name brand engines. All exploded. So, things other besides quality can cause an engine failure. The plugged oil line is one that could happen to anyone.....
So, you need to analyze the failure before jumping in and saying poor quality....Junk.
DW_Crash
OK Guys
Lets talk facts, as this seems like myth buster season, for clarity for those owners of less experience than three months. FOD screens are a very recent addition by most manufacturers. As a guide since the first rc turbines, they have ran 80% of that period without any FOD screens. Were they blowing up regularly during that period. NO[8D]
. The smallest object that can hit the turbine wheel must pass down one of the injector sticks. Thats really small diameter and rather basic fact of turbines.
I am a little confused on Dave's post. Firstly I don't know of any commercial or home built design thats uses a a "rear bearing oil nozzle" I cannot imagine a piece of dirt blocking the oil/air flow except at the front. At the rear the oil feed is the shaft tunnel itself, simply as any blockage would need to completely block the area totally between the shaft to the inner wall. Thats not going to happen even if the turbine was buried 3 feet into the earth at 160krpm flying at max.
"These engines are under high stress. And, it doesn't take much for an explosion". Totally disagree with this asertion as exploding turbines are as rare as rocking horse droppings. If they regularly exploded then the AMA, BMFA and IJCM would ban them because no insurer would give cover. Generally when a turbine lets go its usually to an abrupt amd immediate stop (with lots of damage).
Lets talk about bugs then, our turbines are great little 'food blenders' and even greater as a hot oven inside the CC. I've seen wasps bees and flies ingested and nothing happens at all. I would think that putting 150 ants through might not even give a hiccup in turning over at max rpm, except make a nasty mess inside the CC. Provided the area betwen the comp blades and the wedges is free to turn, now put a screw, bolt or a stone as small as pea through and thats going to reek havoc and shreed metal, but explode a turbine thats a very, very rare occurance.
I'll tell a story that a guy was demonstrating his turbine to 120 engineering visitors at a show and as he lent forward his tie got sucked in. The turbine did not explode but came to abrupt dead stop. He looked a rather arkward and trapped until someone cut tie off. He stripped and cleaned that turbine, ran it again the next week.
So grass hopper [:-] over to you
Paul