No way is that thing gliding 15:1. Velocity XL is supposedly 12-ish. Raptor isn't going to beat that, likely significantly worse. Even if I'm wrong, what's best glide speed? Your guess is good as the "test pilot's."I calculate an 8.5 mile glide from 3000 feet depending on the wind if the glide ratio is 15.
Then he also has a chute.
PM keeps 'whistling past the graveyard' Heat is slowly cooking this bird, and until he addresses this problem in a meaningful way, the bird should stay on the ground.In the latest video, Muller has disassembled the PSRU to replace an o-ring. I thought the condition of the PSRU interior was shocking, and Muller just brushed it off. It has no more than 40 hours or so of operating time, yet it looks like the insides of a 50 year old automobile engine that didn't have regular oil changes.
Clearly the oil is undergoing oxidative and thermal breakdown, and the carbonaceous deposits in the PSRU housing indicate oil temperatures are exceeding 300° F somewhere in the lubrication process. This situation could lead to coking in the turbocharger oil lines and induce failure. It's also possible conditions in the PSRU are causing extreme oil temperatures in that unit.
While exploring this issue, I found this statement regarding the oxidation process in synthetic engine oils:
A reaction (oxidation) will approximately double in rate for every 10°C (18°F) increase in temperature. Which means that the oil life will be reduced by one-half for every 10°C (18°F) increase in temperature.
His cavalier acceptance of oil temperatures in excess of 250° F ignore the implications of operating the engine in that manner. I'm not sure where he is measuring the temperature, or what the ∆T across the oil cooler is. What is the temperature of the oil when it enters and leaves the PSRU?
His assessment of conditions in the PSRU with regards to oil drainback are suspect. He thinks the housing is being pressurized and a larger drain line to the engine oil sump he installed will cure this. This ignores the fact the diameter of the transition fitting at the oil sump remained unchanged. Should the PSRU case have a vent?
There has been no mention of what the optimum oil level in the PSRU should be. I believe the oil supply to the unit is excessive, and the oil level is such that the rotating assembly is operating in a submerged condition.
If this is so, the windage effect is heating the oil and elevating its temperature, and the entrainment of air in the oil is reducing its ability to transfer heat from the rotating assembly to the fluid, which exacerbates the oil temperature rise. Muller has made no attempt to measure the amount of oil being introduced into the PSRU or how much is draining out. Maintaining the proper oil level is critical, yet it is being ignored.
We have also discovered the working temperature limit of the PSRU cover o-ring has been exceeded by 40° F or more, which, along with presumed pressure in the unit, Muller believes is the reason it is leaking. A Viton replacement is being installed. This makes me wonder about the operating temperature rating of the shaft seals.
What should also be a huge concern but of course is not, on the latest flight the PSRU belts apparently jumped on the pulleys. Muller cheerfully explained it has happened before, and the fix will be to increase the spring rate of the tensioner device. There has been no mention of belt tension operating limitations, so we are left to wonder if that is being exceeded. Does he even think of such things?
Each flight exposes more weaknesses and possible points of failure, and it's disturbing to realize Muller doesn't even see them. His blind acceptance of operating conditions which could lead to catastrophic failure of the engine and PSRU expose just how little he understands the risks involved.
The FAA minimum 40 hours of flight test is a minimum, and in the case of funky-wonky-chunky-monkey powertrains like this... 40 hours is probably not nearly enough. The FAA I believe now gives you a reduction in E-AB test hours if you use a certified engine (from 40 to 25??), but in fairness there should be a quid pro quo and a longer or more demanding type of testing for something like this.
Well Well Well, Belt slipping !!!!!! am I surprised errrrrrrrrrrrrrrrrrr NoRevised Belt Tensioner Design !!!! Is it me or does the 'new' design tensioner just squeeze the belt against the pulley ??? rather than be placed 'mid-span' from drive pulley to PRU pulley and provide a proper belt-tension element ?
Of course the last video will not be put on utube.
Suggest all you want, but to step in forcefully is suggesting we abandon our current E-AB freedoms and start down a path of Draconian measure. None of us want that.Is there anybody involved in this tragedy who has any influence, or is willing to just assume the authority, and step in forcefully to prevent this from turning out the way it seems to be headed?
Every landing seems to be performed at relatively high power and high speed. There seems to be no test objective to evaluate and develop experience with the power-off condition. Given the experimental nature of engine and PSRU, and associated vastly higher than typical likelihood of a power loss, in my view the omission of this objective is the single greatest self-imposed risk. This, combined with low altitude operations beyond gliding range (to the runway), for the majority of every flight, including even the portions of the pattern where this could easily be achieved, is particularly puzzling.
All kidding aside, all sarcasm, all punditry and TV show jokes aside.
Is there anybody involved in this tragedy who has any influence, or is willing to just assume the authority, and step in forcefully to prevent this from turning out the way it seems to be headed? I mean somebody will always try to pull a kid out of the street when a car is coming, whether the kid is a brat or not. The explanation above regarding the PSRU seems to be well-informed and foretelling of yet another disaster, even aside from any of the other disasters that are competing to cause this accident.
We're talking about a forced landing... in a state largely covered with trees... in an airplane that lands at about 90... which has this heavy engine and powertrain directly behind the pilot... and an airplane with a pointy nose that will stick into soft dirt... if things are lucky enough to not happen in the trees.
I'm pretty sure this is a perfect recipe for a very bad outcome. Is there anyone who is nearby where this is taking place, who can drop a dime at the FSDO and suggest a ramp check with lots of problems to fix? Is there anyone with enough experience or an impressive enough resume who Peter cannot wave away?
Does Peter have a wife, or kids, or Aunt Claire or a brother?
Let's be clear, you're talking about the prop governor here as the PSRU is belt driven and so therefore no case and no oil level.There has been no mention of what the optimum oil level in the PSRU should be. I believe the oil supply to the unit is excessive, and the oil level is such that the rotating assembly is operating in a submerged condition.
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