On Monday, September 10, 2018 at 8:49:04 PM UTC+2, wrote:
On Monday, September 10, 2018 at 5:56:11 AM UTC-5, AS wrote:
On Monday, September 10, 2018 at 3:39:49 AM UTC-4, wrote:
One potential problem with multiple jets is if one starts while the other doesn’t but pumps fuel through.
Good engineering may help but there is a known issue there. (PM)

Tom - good point but each turbine has its own controller monitoring what it is doing. If it doesn't ignite and run within the set parameters, fuel to it is cut off.

Uli
'AS'

I have been using the twin Jet Cat P300's for a number of years on my homebuilt experimental HP-18J. I have to say that they can be troublesome, especially if they are not operated according to specifications. I have been using diesel fuel with 5% oil for the bearing lubrication. If you use Jet Cat oil or Aeroshell 500 turbine oil the bearings are reliable for one or two seasons tops. This includes a full summer of self-launches and sustainer starts at our mid-west altitudes. I attended Parowan and Dave was one of my helpers who graciously assisted me retrieve the glider from an out landing. That day the failure was pilot error and not the turbines. I had failed to plug in the CPU's prior to takeoff so the turbines and fuel were just extra ballast that day. During the rest of the event, I used the turbines for sustainer. They started consistently at the airport altitude of 6K and also at flying altitude when needed, sometimes above 10K. With the two turbines, I feel more confident that at least one will start when needed. I typically will do a start sequence for both turbines for a climb and shut one down if I go into sustainer mode to extend my fuel endurance. The problems that I have encountered over the years have been bearing failures, one glow plug ignitor failure and one EGT failure. The turbines are in my opinion good but not great. They still have their issues, two of them are better than one for redundancy and for my application of self-launch. In the mid-west I can take off with a 1K runway roll and climb at 500 FPM. During flight one or both can be started for another climb or for sustainer operations. Operation at high density altitudes and elevated temperatures greatly decreases the performance so I choose to use a tow and use them only for sustainer ops. Here is a link for short clip from our mid-west airport https://www.youtube.com/watch?v=xeQIRrZ7JCU I am currently putting a salvaged ASW-27 back together, I am happy enough with the twin turbines to incorporate them into the rebuild of the glider for the same self-launch and sustainer abilities.

Thanks,
Chris

One has to wonder why this company is using traditional instead of ceramic bearings, which require no lubrication.