10/23 Raptor Video

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rv6ejguy

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Well, yes and no.

It really depends on how software is written. Some simple examples are IAT (inlet air temperature), oil pressure, ECT (engine coolant temperature), MAP (manifold absolute pressure)... and so on. Once the ECU starts up, performs sanity checks, and fires up OS, these analog values will be read (via analog to digital converter), transfer functions performed, then appropriate values written to random access memory location specified. This happens regardless if engine is stopped (usually referred to as stalled), cranking, or running. I can't say this is universally true for all ECUs, but I can't think of anything I've worked with that doesn't act like this.

Now, MAP can be both time and crank angle dependent or synchronized (started time based then switches to crank angle burst mode).

As far as reading odd values with engine stopped. A good example is MAF (mass air flow) sensor, it is never truly "Zero" even when within specifications. Mess up transfer function (lookup table), or 2 point calibration with offset, and you can register sufficient mass flow with stopped engine to exceed normal idle state. How do I know, been there done that... Before anybody asks, no I didn't crank with such a large error.

So most OEM ECUs have sanity checks to identify such conditions and revert to a limp mode or simply don't start. But aftermarket ones are far more forgiving. Being forgiving they do need to display and log values, regardless of engine state, windowed (hole in case), stopped, cranking, running.
Not true for our ECUs. Not sure why you'd have any FF, duty cycle or pulse width displayed when none is happening. No injector frequency means zero fuel in reality. Reporting reality seems like a better idea...

MAP isn't dependent on time or crank angle in our ECUs. Not sure why it would be. MAP is simply pressure in the manifold and you can read that even with the engine not running in our ECUs.

MAF is zero with engine not running in reality. Anything other than zero is false.

You can try to justify these errors if you want but in the end they are just plain wrong and the results of lazy programming. True data from logging makes it easy to understand what's going on. Erroneous data doesn't, as we see in this case.
 
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dave wolfe

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OK, my bad. Guess PM doesn't believe in "As Built" documentation.

Don't want to speculate too much, but wonder what his crank case pressure was like? There was enough elevation change for gravity drain, if lines are sized correctly. Most PCV systems from factory are barley adequate, with his turbo setup, who knows if anything was done to address this known emissions related issue. If you understand your engine, too much oil in catch/puke can is an indication of engine health (referring to highly boosted engines)....
I was just looking atthe vids where he modified the redrive. The two bottom tubes off of the oil collar were welded up and a drain added to the case. Then he made a comment about the crankcase being designed to operate under a vacuum so its sealed up to some extent.

Something caused the crankcase pressure to jump and force the oil out. A turbo seal would be on the short list of suspects.
 

rv6ejguy

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I was just looking atthe vids where he modified the redrive. The two bottom tubes off of the oil collar were welded up and a drain added to the case. Then he made a comment about the crankcase being designed to operate under a vacuum so its sealed up to some extent.

Something caused the crankcase pressure to jump and force the oil out. A turbo seal would be on the short list of suspects.
Not sure where you'd obtain a vacuum in the crankcase on a turbo diesel engine without a scavenge pump/ dry sump system? I think Peter doesn't know what he's talking about. There will be considerable blowby on a turbo diesel (high CR and high boost) and you'd need a serious crankcase ventilation system to handle that. I don't think there is enough exposed area on a failed turbo compressor seal to generate any significant volume of air to overwhelm the crankcase vent system.

If the compressor seal failed first, while there was still oil pressure, the compressor housing and all the induction plumbing would have been full of oil and you probably would have seen a lot of smoke out the exhaust. A piston seizing up from lack of oil could cause the pin boss to fail

Holed piston or failed ring land on that piston could have caused that short boost spike and huge volume of air into the crankcase.

Would love to see at least a partial teardown of the engine.
 
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lelievre12

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I did.

PM had arrested essentially all of the descent rate and was floating down the runway when the roll event occurred. As I suggested previously, given the lack of any wing bending evident in the video, the chance that there's any damage to the wing structure (other than the lower fence) is small. It should be inspected, as should the gear (jack the plane up and check for play or movement in the mounting structure, particularly since he's had one failure of the gear mounting structure before) but _IF_ the gear was redesigned correctly for a 10 fps descent rate, it should be fine.
Its an interesting topic. My understanding is that the inelasticity of carbon (what makes it stiff) also makes for a sharp UTS and yield. Its not a material that shows clearly where it was overstressed and its also a material that doesn't soak up shock loads well. As the yield is sharp it breaks clean when strain limit is exceeded. Kind of makes it hard to diagnose just how 'close' you got to UTS when you bang a carbon wing. Not really the kind of material you want to fly again when impacted?

1613407729058.png

If you were pressed I guess Peter's camera's might reveal just how much wing tip deflection occurred at the impact and provided this doesn't exceed the sand bag tests then you might assume that the strain didn't exceed material limits in his wing design. He did do sand bag tests right??
 

Rataplan

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Such suggestions have been addressed with "Why? I'm replacing it anyway."
Any opportunity to learn isn't worth Peter's time.
But if one buys from e-bay a secondhand car engine should't it be normal to take the engine apart and check all components ? Beside look to the work and testing official companies do to convert or rebuild a car engine into a plane engine. I'm certainly not an engine man but still eager to learn and today with google and forums you can learn a lot of over 100 years aviation . The USA has so many homebuilders with professional knowledge it is just a heaven for serious aviation addicts , for people who are just interested in aviation , pilots, mechanics and builders. Why PM neglect all that knowledge and experience ? This whole raptor project became a soap , you know its all shh t but somehow you dont want to miss any episode
 

Rataplan

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Its an interesting topic. My understanding is that the inelasticity of carbon (what makes it stiff) also makes for a sharp UTS and yield. Its not a material that shows clearly where it was overstressed and its also a material that doesn't soak up shock loads well. As the yield is sharp it breaks clean when strain limit is exceeded. Kind of makes it hard to diagnose just how 'close' you got to UTS when you bang a carbon wing. Not really the kind of material you want to fly again when impacted?

View attachment 107487

If you were pressed I guess Peter's camera's might reveal just how much wing tip deflection occurred at the impact and provided this doesn't exceed the sand bag tests then you might assume that the strain didn't exceed material limits in his wing design. He did do sand bag tests right??
Just take a string of carbon fibre and you can't pull it aparts with your hands, than make a simple knot halfway the string and pull again. It will break immediately.

At least he should check on delamination as I doubt the quality of its build .
 

Marc Zeitlin

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Its an interesting topic. My understanding is that the inelasticity of carbon (what makes it stiff) also makes for a sharp UTS and yield. Its not a material that shows clearly where it was overstressed and its also a material that doesn't soak up shock loads well. As the yield is sharp it breaks clean when strain limit is exceeded. Kind of makes it hard to diagnose just how 'close' you got to UTS when you bang a carbon wing. Not really the kind of material you want to fly again when impacted?
All true, and I won't claim to be a composites expert.

However, impact is generally a localized event - the impact here was on the lower fence only. The rest of the wing, from a few inches away from the fence all the way to the root, saw NO impact - only a large strain riser over a relatively short period of time as the wing bent the small amount that it bent. So I would NOT interpret any of the wing, other than the non-structural fence, as having seen an "impact".

If you were pressed I guess Peter's camera's might reveal just how much wing tip deflection occurred at the impact and provided this doesn't exceed the sand bag tests then you might assume that the strain didn't exceed material limits in his wing design.
So that's what I'm going by - the amount of deflection of the wing is FAR less than would be imparted by the 3.8G, 4.4G or 6G loading that would have been imparted by testing, or that would be predicted by analysis. The tip didn't move a couple of inches at most with respect to the root - that's a pretty low loading. Remember, the airplane was not fixed at the wing root - any force at the wingtip would just move the whole plane, restricted only by the inertia of the rest of the plane, not a fixed cantilever end.

He did do sand bag tests right??
Good joke!
 

Marc Zeitlin

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Just take a string of carbon fibre and you can't pull it aparts with your hands, than make a simple knot halfway the string and pull again. It will break immediately.
I haven't tried this, but what does tying carbon fibers into knots have to do with straining a carbon fiber in a matrix, or even with localized impact?

At least he should check on delamination as I doubt the quality of its build .
While I agreed earlier that checking the wings, attach points and landing gear is obviously a good idea, particularly since it won't take an hour or two to do so, your implication of poor composite build QUALITY (as opposed to poor composite build DESIGN) is unfounded. PM did not do the composite fabrication - a very competent composite builder did, as you'd know if you read through the aforementioned 83 gazillion messages in the previous thread :).

And as one of the few people that's actually seen the design documentation and analysis for the Raptor, such as it is, the structure (aside from the absurd weight) is one of the lower concerns on my histogram of issues with this plane.
 

Rataplan

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All true, and I won't claim to be a composites expert.

However, impact is generally a localized event - the impact here was on the lower fence only. The rest of the wing, from a few inches away from the fence all the way to the root, saw NO impact - only a large strain riser over a relatively short period of time as the wing bent the small amount that it bent. So I would NOT interpret any of the wing, other than the non-structural fence, as having seen an "impact".

S

Good joke!
( (the force on the wingtip) * ( distance to root) ) / (distance between attaching bolt) is aprox the force on the bolts.

Many planes who made a groundloop at almost zero speed have no damage on the wingtip but have internal damage at the root cq attachment of the wings at the root.

combine it with shock impact and the very basic mechanics shows inspection is certainly needed.
 

Turd Ferguson

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Would love to see at least a partial teardown of the engine.
Any opportunity to learn isn't worth Peter's time.
Me too! I think the big end of the con rod broke. I'd also be interested in seeing if there was any interference between valves and piston. However, just watching him work in some of the videos, I don't think Raptorman is very mechanically inclined nor interested in mechanical forensics.
 

Marc Zeitlin

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( (the force on the wingtip) * ( distance to root) ) / (distance between attaching bolt) is aprox the force on the bolts.
Thanks for the explanation of calculating moments. I'm reasonably familiar with the analysis methodology.

Many planes who made a groundloop at almost zero speed have no damage on the wingtip but have internal damage at the root cq attachment of the wings at the root.
Without knowing which aircraft you're discussing, what type of damage was incurred and how their wings are attached, an argument by similarity may or may not be applicable.

What I DO know is what the structure of Raptor's wing attachment is and I DO know that with a given force at the wingtip, a proportional displacement of the wingtip would be seen. And since that displacement looked to be far less than would be created by a high "G" aerodynamic maneuver, I'm willing to state that IMO, the stresses created by the impact on the wing root structure were well below the design limits. Am I 100% sure? No. Of course not. But this is my engineering opinion based on the evidence presented. Present evidence indicating otherwise and I'm happy to change my mind.

combine it with shock impact and the very basic mechanics shows inspection is certainly needed.
I already discussed the shock impact issue with respect to location of the impact in post 1,610. And I also agreed at least a couple of times that inspecting the wing and landing gear is a good idea. So with what, exactly, are you arguing?
 

BBerson

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I have intentionally dragged the wing tips on my gliders hundreds of times. Nothing like a ground loop.
The factory told me the Grob wing tip can deflect 4 feet without breaking. I think it moves perhaps 2" in normal use.
 

Dead on Time

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I've used .42 BSFC at high power on Raptor due to the dreadfully restrictive turbo setup.Call that 345hp but we know from the acceleration runs, static thrust and ROC that can't be right. Using 76 mg instead, yeah around 273hp which agrees with other observations better.

No flow transducer as far as I know, just measured from injector pulse width and frequency.
The VAG 3.0 V6 TDI engine injectors are coded for fuel flow variation. When the injectors are installed on the engine the code is inserted into the ecu so the ecu knows the individual injector variation and trims the injection pulse accordingly for a very smooth running engine.

The Raptor 3.0 V6 TDI derivative seems to use a constant 2,000 bar rail pressure. Unless the engine developer knows the nominal flow characteristic of the injectors @2,000 bar and has programmed the ecu accordingly, or mg/stroke against a known fuel flow figure from a transducer perhaps, any mg/stroke figure on the engine log is suspect.

There's is also the issue of return flow from each injector. Each injector has a fuel return line which feed into a pressure regulator and holding the injector return outlet at 10 bar. The outlet of the pressure regulator then feeds back into the fuel tank. (is there a fuel return installed on Raptor?) So the actual engine fuel consumption is likely to be less than 96mg aka 76mg/stroke as shown on the engine log, taking into account the percentage of fuel return flow.

From the TO acceleration/time calculations the engine output is likely less than 300hp. From fuel flow calculation the engine output is likely less than 300hp. If the Raptor engine is a Series III TDI engine then the Raptor TDI derivative makes less output than the standard VAG Series III engine! (320hp from memory...dangerous)

DoT
 

rv6ejguy

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The static thrust tests also show less than 300hp, so many cross checks here don't support the 400 ish Peter estimates.

The completely mismatched turbos mostly explain the low power output here IMO.
 

Rataplan

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I have intentionally dragged the wing tips on my gliders hundreds of times. Nothing like a ground loop.
The factory told me the Grob wing tip can deflect 4 feet without breaking. I think it moves perhaps 2" in normal use.
Dragging is not the same as an impact, there is a difference between static forces and dynamic forces. the wingspan of a Grob is larger than of the raptor so 4 ft deflection isn't that much I've seen an ASW20 finishing with the tips almost touching each other so that all depends on design of the plane, and cant be a mark or indication for other planes.

Beside Grob built aircraft are professional designs and they like all German glider factories are specialised with decades of experience in building high tech glider wings.

You cant compare that with an untested homebuild aircraft .

Beside much dragging your wingtip will cause over a time , if you like it or not, backlash in the attachments pins/bolts.
 

wsimpso1

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On the wing tip touch:

The roll moment of inertia of these canard ships is modest, the landing gear was also putting in a rolling moment, I do not expect a huge force developed during a wing tip touch like this. If it was a taildragger in the midst of a ground loop, that would be another matter. Then the long slender wing will have pretty substantial flexibility, and so would require a lot of bend to get to forces sufficient to do damage.

Graphite epoxy does have strain to failure areound 1% while primers, fairing compounds, etc, tend to be higher. If the the structure is fine, you will not crack the paint. Substantial overloads bend fasteners and produce substantial deflections. Parts lose alignment, paint and fairing compounds crack, you can see this doing a decent walk around, and indeed we count on this feature in flying composite airplanes. If PM walked around and looked at everything on that wing, and found nothing more amiss than the scarred up wingtip fence, it is probably OK.

On the seal. We humans build an impressive number of automobiles, something like 90 million every year, each with three to six seals very much like the one that was pushed out, and retained only by a press fit. They routinely last and stay put longer than the car lasts. With an appropriate press fit between the seal and bore, a snap ring is not needed. With a too modest press fit, it will leak. Skipping the snap ring is hardly a cardinal flaw. Most likely, that seal was pushed out by excess pressure inside that housing...and I too do not buy the theory that the failed turbo seal let enough air through to do that.
 

PPLOnly

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On the wing tip touch:

The roll moment of inertia of these canard ships is modest, the landing gear was also putting in a rolling moment, I do not expect a huge force developed during a wing tip touch like this. If it was a taildragger in the midst of a ground loop, that would be another matter. Then the long slender wing will have pretty substantial flexibility, and so would require a lot of bend to get to forces sufficient to do damage.

Graphite epoxy does have strain to failure areound 1% while primers, fairing compounds, etc, tend to be higher. If the the structure is fine, you will not crack the paint. Substantial overloads bend fasteners and produce substantial deflections. Parts lose alignment, paint and fairing compounds crack, you can see this doing a decent walk around, and indeed we count on this feature in flying composite airplanes. If PM walked around and looked at everything on that wing, and found nothing more amiss than the scarred up wingtip fence, it is probably OK.

On the seal. We humans build an impressive number of automobiles, something like 90 million every year, each with three to six seals very much like the one that was pushed out, and retained only by a press fit. They routinely last and stay put longer than the car lasts. With an appropriate press fit between the seal and bore, a snap ring is not needed. With a too modest press fit, it will leak. Skipping the snap ring is hardly a cardinal flaw. Most likely, that seal was pushed out by excess pressure inside that housing...and I too do not buy the theory that the failed turbo seal let enough air through to do that.
My old company owned a lot of private jet aircraft, and occasionally we'd have one that would scrape a wing on landing. The inspections for those were substantial. From weeks to months out of service depending on what the engineers said we needed to do. There is simply no room for "probably" when it comes to your wing. Especially with a clean sheet airframe with limited data. If he cannot calculate the actual loads of his wing strike than he needs to do a thorough inspection, not a walkaround, of his structures. I am hoping that is what he is doing over these next 2 weeks.

He really should be applying these same principles to his eBay engines too, as I stated before. He should be bringing them to a known-state with an overhaul before flying it. He has no idea the condition they are in upon receipt.
 

Victor Bravo

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I've seen an ASW20 finishing with the tips almost touching each other so that all depends on design of the plane, and cant be a mark or indication for other planes.
Well they won't "almost touch each other", but the '20 wingtips will indeed flex upward about 4 feet during a normal XC or contest flight in desert/mountain turbulence. I'm pretty sure they would break well before they actually touched, but at my advanced age and decrepitude I'll have to leave that to the LBA test pilots (and one or two US contest pilots I knew) to prove that out for certain :)

The fact that the rather complex aileron and flaperon functions on that wing will continue to function correctly during a four foot deflection is a magnificent achievement for Waibel and his design team. One of the great honors in my time was to be able to shake Waibel's hand in person and thank him for the AS-W20.
 
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