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#101
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Js3 jet catastrophic failure.
Good idea. For a lot of things that rotate, especially large or fast, never good idea to "stand in the plane of rotation" about 90* to shaft axis when things are spinning. This goes for lathes, lawnmowers, prop planes, turbines/jets, etc. When things come loose or fly off, they go out in direction of plane of rotation. and winch engine water pump mounted fans I consider this idea - generically avoiding the plane of rotation of rotating 'stuff' whenever reasonably possible - an aspect of ground-based "situational awareness." There's a reason clutch scatter shields were developed for cars, rotating machinery, etc. Sure the risk is generally low, and I sure don't lose any sleep from fear of 'rotating stuff,' but why provide Murphy additional opportunity? Bob W. --- This email has been checked for viruses by AVG. https://www.avg.com |
#103
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Js3 jet catastrophic failure.
Has anyone else seen the new rotary engine under development by a company called Liquid Piston? If jalf of what they are claiming is true, it will be a perfect engine for self launchers.
Branko XYU |
#104
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Js3 jet catastrophic failure.
Very nice engine.
I don't see black magic or crazy claims around how it works. Also i don't believe that it will have the efficiency claimed, but if it is better than the 2 stroke engine they have a winner. Durability and emissions will be an issue too, but again it seems to be very cheap to produce and replace. If it works, we will see the Chinese version in some years. And if it works (at least the same as a 2T) I want it for all the hybrid projects. |
#105
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Js3 jet catastrophic failure.
On Thursday, August 30, 2018 at 4:46:35 AM UTC+2, Charlie Quebec wrote:
In the last east issue of Gliding Australia there is an incident report shown below. During the course of a cross country flight, the pilot elected to start the jet sustainer to self retrieve. The engine started normally, and the pilot tracked for the home airflield The engine failed catastrophically 830ft. AGL and a safe outlanding was conducted. Things that make you go hmmmm... I own and operate an EASA certified JS1 w/ an M&D jet sustainer engine in the Alps. I have found the system very reliable, but I don't trust it to save me from an outlanding or, worse, being trapped down low in an alpine valley. With one exception I kick myself for this very day, I have always started the engine within easy range of an airport. Often I'll start the motor earlier to avoid a situation where I am forced to fire it up down low, when my only option is a field. I am perhaps too prudent but I fly over some pretty nasty territory. Even when it looks flat, it's not. And the JS1-21m requires some care to land safely and short. The nicest thing about the jet vs. classical sustainer is this - if it does not start, you have almost 0% added drag with the thing hanging out the fuselage. The proof is in the pudding... Shortly after I received the beast, I fired up the motor before a cross-country flight to re-assure myself it would start. I usually don't let the automated system retract the motor when the EGT sensor says the hardware is 50C. I do that manually and usually wait for the equipment to cool to much lower tempertures before stowing it. I must have been distracted with ATC or something. I was flying around the Lyon TMA that day. I shut the engine system off withough retracting the engine. I managed for fly 650 km with the jet windmilling. I did not even notice. As for fuel, I usually use BP excellium and Cross T 2 stoke oil. I wish I could buy the Shell Gas-Diesel in my kneck of the woods. I've never noticed any start up issues related to altitude or temperature. Then again, I can't imagine any reason why I might start the beast up at 3000m. I can glide at least 100km on that without the motor. Yes, the mountains are high in the Alps but the valleys are quite low and the density of airports is more than adequate. I can imagine a high and hot start in South Africa or the Western US. Different conditions. A+ |
#106
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Js3 jet catastrophic failure.
I've been digging around trying to find out what the process has been for pilots that have added jets other than the MD-TJ 42. This group seems to have a lot of knowledge on this niche subject. The jets are coming down in price and getting a lot more reliable to start, so it seems it would be a more considered option for a lot of pilots. Are there many self-installs, or are there a handful of companies that specialize in the retrofit?
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#107
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Js3 jet catastrophic failure.
On Monday, October 26, 2020 at 6:33:02 PM UTC-4, wrote:
I've been digging around trying to find out what the process has been for pilots that have added jets other than the MD-TJ 42. This group seems to have a lot of knowledge on this niche subject. The jets are coming down in price and getting a lot more reliable to start, so it seems it would be a more considered option for a lot of pilots. Are there many self-installs, or are there a handful of companies that specialize in the retrofit? You didn't say where in the world you are but for the US, Bob Carlton in Moriarty would be my first choice to call, if I wanted to have 'my ride pimped out' with a jet. Uli 'AS' P.S.: Bob - as soon as that lottery thing works out for me, I'll be giving you a call! ;-) |
#108
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Js3 jet catastrophic failure.
I'm in the US and familiar with Bob. What he does is fantastic, but I'm more curious about some less expensive, less pimped out options. Everything I've seen of his so far uses PBS engines which are extremely expensive. The Jetcats and some other options are much more affordable and I know there are pilots that use them.. I'm wondering how they went about the retrofit.
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#109
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Js3 jet catastrophic failure.
a lot more reliable to start
mmm, on the RC side I'm not sure they are much better since I last posted on this thread couple years back. Since then: -bad egt probe -bad glow plug -newish turbine had stiction on the starter motor but if you could reach in and spin the bendix by hand it would start. -another with bad starter motor. But no catastrophies. Above were all fixable for a price. Darren |
#110
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Js3 jet catastrophic failure.
I've been operating the microturbines for about 15 years (only up to the 90lb thrust class) and all those problems have been addressed for much more reliability. The EGT probe sheaths were switched to much higher temperature materials and were moved internal to avoid being deflected in any way that would fatigue the material to a point of breaking. The glow plugs were horrible and failed all the time. They used to be the ones used in RC nitro engines but are now ceramic and have proven to last way beyond multiple service intervals. The starter motors have transitioned from high friction brushed motors to virtually zero friction brushless. Same with the fuel pumps. I'm just addressing Darren's list but there are a lot of other improvements. The biggest issue I ever found consistently with starting the microturbines is variations in the atmospheric conditions that don't jive with the programmed start parameters which are set for a most likely "window" of conditions. But there are operator techniques to remedy even this scenario on the fly.
Obviously I'm biased toward the jets but always looking for the failure stories because it motivates me to figure out how the potential for those situations can be minimized. |
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