10/23 Raptor Video

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BBerson

Light Plane Philosopher
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Port Townsend WA
Looks like aero momentum has a turbo engine for up to 30,000 feet. Maybe PM should have a look.
He said he has a dyno. Not sure what other testing equipment is used or if the customer does the testing.
 

231TC

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Aug 29, 2020
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110
I calculate an 8.5 mile glide from 3000 feet depending on the wind if the glide ratio is 15.
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."
 

231TC

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Aug 29, 2020
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Then he also has a chute.
This is something I've been wondering about. Is the chute actually operational? I remember a video where he put the chute itself into the plane, but keep seeing comments about the chute not being installed, and I don't remember seeing the rocket install. Anybody know for sure?
 

Victor Bravo

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You know, I just realized that this really is the aviation equivalent of a lowbrow reality TV show. We're watching the disaster take place the same way as we watch Billy-Bob get rejected on Redneck Bachelorette, or watch the Kardashians ruin a million dollar wedding because the fake boobs fall out of the dress.

It's horrifying to realize that it's the exact same principle... the whole world sees that Billy-Bob is putting on the bright purple suit to impress Trailer Tiffany... but he doesn't see how ridiculous it is, and stands there smiling through missing teeth as if he's on the cover of GQ... and we're all just yelling at the TV saying "NO... wear the black tuxedo, she's gonna kick you to the curb with that purple velour jacket!!"

And we show up the next week, every bit as addicted as the idiots sitting in front of the TV, because we can't walk away from seeing it. I'm actually embarrassed, because the "reality TV" shows are not going to have anyone get really hurt and this one will.
 
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5761RF

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Nov 26, 2020
Messages
16
In the latest video, Muller has disassembled the PSRU to replace an o-ring. I thought 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.
 

Victor Bravo

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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?
 

wwkiefer

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Joined
Aug 27, 2014
Messages
12
Location
kalamazoo, michigan
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.
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.
 

Malish

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Joined
Oct 11, 2013
Messages
565
Location
Russia. City of Volgograd
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.
Used to be minimum 60 hrs with not certified power plant.
 

rv6ejguy

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Jun 26, 2012
Messages
4,154
Location
Calgary, Alberta, Canada
The nitrile O-rings would normally be fine in this PSRU as you'd normally have OTs below 225F. Once it became clear that they were going above 240F on every flight, he should have installed the Viton ones right away but even before that, the obvious fix was a proper air to oil cooler to remedy the temperature problem properly.

Yet another wrong guess on the oil leak led to wasting time installing the larger drain line on the PSRU.

As far as coking oil lines on the turbo with synthetic oil, no. It's nowhere near hot enough here to do that. Coking in the turbo bearing housings on the turbine side, yes, possible. The black oil is very normal for diesel engines in only a few hours, not evidence of oxidation. 250 OTs will reduce the engine main and rod bearing life substantially though.

Muller was surprised by the belt slippage after a bunch of hours with it not slipping. He will have plenty more surprises with this PSRU layout once he runs the power levels up over extended periods. No way this design will make it into production. Flying around at half power isn't very taxing although since he's done no strobescope testing on the ground to look at belt/ tensioner dynamics, he's probably stumbled onto a belt/ tensioner harmonic at low rpm/ power which caused the belt skip. He's really lucky that it didn't completely shred. I assume he'll re-use the belts again though, justifying that by saying he's ok with that...

As I said in a reply to a fan boy on YT yesterday, who couldn't wait to be flying his own Raptor, this airplane is a long ways away from loading up full fuel, 4 people and climbing directly to FL250 on a 90F day in pressurized comfort. So far it's only demonstrated that it can climb at 500 fpm, to 3000 feet with one person and almost no fuel on a 60F day with no pressurization. It effectively won't climb at all with 1500 pounds more payload aboard.
 

Pops

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USA.
I'm thinking of not watching an more of the videos. I'm afraid of what is going to happen next. Of course the last video will not be put on utube.
 

BBerson

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Port Townsend WA
Black oil is normal like Ross said. This is an extreme research experimental on the edge of limits. I think he is only collecting limited data (not full flight test program) before a reassessment of the business, but not sure.
 

narfi

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Feb 23, 2016
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Alaska
Of course the last video will not be put on utube.
With the colder temperatures my fingers arent surviving in the tent very long each evening, this has led to more youtubing with my wife.
In the past youtube was never interesting, and I would never sit in front of a computer watching youtube for more than a quick tutorial on something I was trying to do. However, with smart TVs and firesticks now, youtube can be watched on the big screen from the comfort of my evening easy chair, so once I have eaten, taken a hot shower and got the tingling out of my fingers.... we settle in for an evening of 'reality youtube'.......

After watching the latest of the zenith SD build videos, we watch a couple of boat building ones, both more interesting to me, then with the necessities out of the way we watch the 'drama'.... reality sailing couples.... seems to be big money these days for the top few in each catagory, but after one or two selected how to or helpful videos, or even travel destinations we are interested in, enough to say, 'yeah, we kind of like them, maybe we will watch some more', it becomes very obvious how scripted they are and we quickly get annoyed and hunt for something else.

A lot of words to say, they often 'produce' life threatening drama where something catastrophic is about to happen, or they loose control of the drone and the battery is about to die, or they drop their gopro in the water, etc.... but it detracts from the story for me because I am stuck thinking..... 'if they died, then how did they release this video?", or "if the drone went off and dropped in the ocean, how are we watching footage from it?", or "if they didn't recover their gopro, how come we are watching footage of the bottom of the boat as it sinks?".......

If you are watching a just released video, then all is fine, if you are watching a channel that was putting videos out every week or two and then suddenly stopped 3 years ago(there are quite a few channels like that)..... I try not to watch those as I like happy endings and avoid morbid curiosity.
I read a blog with weekly updates about a big catamaran being built in a back yard in Australia by a husband and wife and their daughters, so happy, so excited, so motivated, making a little progress each day and week, it was pretty interesting. Click to next post and she is saying, "It has been a year since anything has happened on the build, we divorced and it has been a terrible year, today he came and took the boat." click next post... "It has been 5 years, I am not quite so bitter now and often think maybe I should build my own, maybe some day..... The End"

What a crappy ending. We don't want Peter to die, we don't want him to become disillusioned and shrivel up into some old folks home forgetting all about airplanes......

I wish him success and a happy ending, I just don't know how that will happen, and because it is still ongoing and the show is still in the first couple of seasons we are still addicted. Drag out the show too many seasons though, and the viewers will get bored and move on to something new.
 

bmcj

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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?
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.
 

PPLOnly

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Dec 12, 2020
Messages
88
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.
Well when you are scared of dying due to deep stall it looks like landings will be done 20+ knots fast and we'll never investigate slow speed handling characteristics. Plus, doesn't it have a parachute? That may be the engine failure procedure he is planning on using if something happens rather than trying for a power off landing.
 

PPLOnly

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Joined
Dec 12, 2020
Messages
88
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?
His reaction to Wasabi wanting ultra-critical issues fixed and a longer runway should be all you need to know. From what I also understand he is single and unattached, so he is more or less free to risk himself however he sees fit. I actually don't know what the goals are here, we are already at autopilot testing but with an unreliable(?) pitot system. How do we not know the stall speed yet?
 

poormansairforce

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Just an Ohioan
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.
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.
 
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