Raptor Composite Aircraft

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wsimpso1

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We have talked this to death already. Sanjay had no intention of flight that day - he had deliberately removed the batteries (substantial they were, they were for Car mode operation) from the nose to see if he could lift the nose at all, and he did know that put the CG way too far aft for controllable flight. The big flaw was that going anywhere near flight speed with an unflyable configuration is really bad practice, as the abort from inadvertant liftoff is to perform first flight.
 

wsimpso1

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The Detroit Flying Car crash video has been thoroughly discussed here as an example of incorrect or lack of incremental high speed taxi testing.
Marc's last point that flying the Raptor prototype at all provides no useful purpose, is most compelling.
If the Detroit Flying Car company had slowed testing and found the rotation flaw, it could have been fixed. Instead the company is likely out of business.
Detroit Flying Cars is just Sanjay, and was a side venture for him. He has recovered physically from that nasty thump.

Rotation Flaw? Sanjay had already found that in flight configuration, he could not lift the nose. He then removed the batteries from the nose for that test run knowing that the airplane was in an unflyable configuration and did not intend to fly at all. High speed taxi tests sometimes abort to flight. In his case the airplane was so unstable in pitch that once the nose lifted it continued up into flight range and flew away wildly divergent in pitch. Prudent test pilots make sure that the airplane and themselves are ready for an abort to first flight. He violated that important bit of protocol ...

As to the company being gone, we shall see if his fertile mind has come up with new approaches and if he is willing to build another prototype.

Billski
 

rbarnes

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We have talked this to death already. Sanjay had no intention of flight that day - he had deliberately removed the batteries (substantial they were, they were for Car mode operation) from the nose to see if he could lift the nose at all, and he did know that put the CG way too far aft for controllable flight. The big flaw was that going anywhere near flight speed with an unflyable configuration is really bad practice, as the abort from inadvertant liftoff is to perform first flight.
Which was my entire point since this is EXACTLY what Peter not only says he wants to do, but we have been actively watching him do repeatedly. Frankly with the way canards fly and rotate at liftoff I'm surprised some kind of loss of control excursion due to inadvertent flight hasn't happened already. Peter has no way of knowing whether the plane is currently in an unflyable configuration or not. The scale model flew poorly. Changes were made. And nothing retested.

The post was also in response to the statement that builders have been testing their own vehicles for a 100 years. And yes they have, with unfortunate results for many of them. Think a test pilot would have tried what Sanjay did ? "Get there itis" affects pilots and builders. That's another reason to bring in a detached 3rd party to do flight testing.
 

MolsonB

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Peter's ego is hurt.
That and the fact they basically slandered me with a slew of things said about me that were simply not true.
Anyway, too much bad taste in my mouth now to move forward with them.
Sadly, we know the path this is headed down. Like Wasabi said.
Armed the gun and put in the hands of the child and we are telling him please don't point it in your face
 

MolsonB

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I'm surprised some kind of loss of control excursion due to inadvertent flight hasn't happened already
It did happen awhile ago before listening to people about having counterbalances on the control surfaces. During a high speed taxi run, got to fast and the side sticks were slamming back and forth. You can clearly see his face and body reactions to it, he's not test pilot material.... He reacted to the situation (tried to strong arm the control sticks) without fixing the situation (slow down and brake).
 

BBerson

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Rotation Flaw? Sanjay had already found that in flight configuration, he could not lift the nose. He then removed the batteries from the nose for that test run knowing that the airplane was in an unflyable configuration and did not intend to fly at all. High speed taxi tests sometimes abort to flight. In his case the airplane was so unstable in pitch that once the nose lifted it continued up into flight range and flew away wildly divergent in pitch. Prudent test pilots make sure that the airplane and themselves are ready for an abort to first flight. He violated that important bit of protocol ...
He went far beyond stall speed with excess power and energy enough to reach 100 feet. The rotation flaw he was aware of should have been approached gradually. If the batteries were temporarily removed only to test rotation while making the CG too far aft, then he made two mistakes.
Even a test flight run with a correct CG should be done extremely gradually.
I talked to Sanjay at Oshkosh. I hope he can return to his project.
 
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lelievre12

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For those interested in the Jet-A v Diesel discussion, the Thielert CD135 (now Continental) engine initially used a stock Mercedes OM668 engine with a 'standard'' Bosch automotive CP-1 high pressure fuel pump. This pump elevates fuel pressure to the common rail (~20,000 psi). The later CD155 engine used a OM640 engine which originally came with a Bosch CP3 pump. This is what it the pumps look like:

CP1 to CP3 upgrade 5.5KG.JPG

However in the later CD155 motor Thielert chose not to use the CP3 pump and stuck with the CP1 pump, instead making a custom cam bulkhead to mount the old pump to the new engine. Why? Because Thielert spent a ton of time and effort converting the CP1 for service using lower lubricity fuels such as Jet-A. We know this becuase Thielert patents are all about the case hardening of the pump surfaces of the CP1 pump which is internally lubricated by the fuel, not the engine oil. See:


The patent discusses clearly their problem: "During operation of the Diesel engine according to the common rail principle with aircraft fuel has to be shortest Operating time can be expected with a total failure of the high-pressure pump. " Even after case hardening, Thielert had a number of engine failures due to rapid wear in the pump (and loss of injection pressure).

Accordingly, since Peter has used a stock VAG (Volkswagen/Audi) 3.0 TDi engine which also uses a Bosch common rail injection system, it will not be possible for Peter to run this engine with Jet-A fuel without additives. Or in the alternative, Peter will need to fit a Technify or Austro case hardened fuel pump which should not be that difficult to install.

If he remains with Diesel, of course the issue is that it's cloud point is not very low and so warming the fuel is crucial if flying to altitude. I believe Peter has installed a tank warmer however the effectiveness of this (particularly at low tank levels) would need to be verified carefully. Any cloudiness would quickly block the fine inlet filters of a diesel engine and cause starvation. Ice in the fuel will do the same as happened to the 777 that crashed on the threshold at Heathrow. So yes, a diesel engine will happily burn heating fuel, kerosene, Jet-A or even peanut oil, however with a high pressure common rail system it must first be injected which is not that straightforward.
 
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wsimpso1

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He went far beyond stall speed with excess power and energy enough to reach 100 feet. The rotation flaw he was aware of should have been approached gradually. If the batteries were temporarily removed only to test rotation while making the CG too far aft, then he made two mistakes.
Even a test flight run with a correct CG should be done extremely gradually.
I talked to Sanjay at Oshkosh. I hope he can return to his project.
Completely agree. I just did not want other readers to think that Sanjay thought the airplane was configured for flight. I hope that the lesson is not lost on PM.

Bill
 

pictsidhe

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Peter has indeed installed a 'tank warmer' he uses the fuel to intercool the charge air. I have a nasty feeling that that may heat the fuel to the point the structure wilts. Naturally, Peter has done no calculations and also hasn't given out enough construction details for anyone else to do them. I don't think he is even monitoring tank temperature. If I were the test pilot, I'd insist on a gauge for that...
 

Rik-

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I am not an aircraft designer so I take what other non designers/engineers say with the same value as my own comments. However I wonder if the solution to Peter's design is merely as simple as what the comments here say?

-Loose 1,000 lbs (or more)
-Change engine to a normally accepted aircraft engine type (yet this will not loose 1,000 lbs)
-Different control system so there is less play in the controls
-More wing area, (I guess this means wider wings?)
-Eliminate Peter from the equation and install another candidate for the role.
-Just purchase a Velocity

Peter, good-bad-ugly, was telling the bad in the video with Wasabi. I was watching it and thinking, "you cannot say he didn't tell you that his sister is fat, ugly and has Covid 19!" before you married her as he was on their video saying the bad and I'm sure there was many of those revelations that were not in the video.

Is the width of this aircraft within the "normal" width for a canard designed aircraft?

Where on earth is all this weight in the aircraft build? We've seen in Peter's video compilation that the console tunnel is at leas 1/2" thick with no core. Is the entire fuselage 1/2" thick solid CF? Was this to some composite engineer's design or a "this looks about right for what I need" move?
 

TarDevil

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He went far beyond stall speed with excess power and energy enough to reach 100 feet. The rotation flaw he was aware of should have been approached gradually. If the batteries were temporarily removed only to test rotation while making the CG too far aft, then he made two mistakes.
Even a test flight run with a correct CG should be done extremely gradually.
I talked to Sanjay at Oshkosh. I hope he can return to his project.
What happened to Sanjay has as much to do with gear geometry than anything else. The main gear on the Detroit machine wasn't just aft of CG, it was aft of EVERYTHING. I can easily raise the nose gear of a C150 or similar. A car of similar weight I couldn't budge. There just ain't no "gradual" in getting those front wheels raised.
Raptor isn't that bad, but it still has a proportionally high amount of weight on that NG.
 

BBerson

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What happened to Sanjay has as much to do with gear geometry than anything else. The main gear on the Detroit machine wasn't just aft of CG, it was aft of EVERYTHING. I can easily raise the nose gear of a C150 or similar. A car of similar weight I couldn't budge. There just ain't no "gradual" in getting those front wheels raised.
Raptor isn't that bad, but it still has a proportionally high amount of weight on that NG.
Yes, I think I was first to point out the aft gear geometry on this thread a year ago when it came up.
It is a problem of roadable airplanes. The only logical solution is to reposition the gear forward for flight with the wing retraction.
 

Victor Bravo

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There may be a reason or an attempted reason for the fuselage structure to be half an inch thick carbon. It may have been an attempt to create a more crashworthy structure, using the same material the airplane had been built out of. I have no idea if this is the case. But even if it was an attempt at safety, the presence of a structures engineer would have been appropriate.
 
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