Raptor Aircraft

Hate-wise, he’s nowhere near where Jim Bede was in his heyday, or Jim “Zoom” Campbell when he was suing members of rec.aviation.homebuilt. On YouTube, there are other contenders today. I’d start a “Who’s the worst Youtuber?” thread, but there’s no use dwelling on stuff you can readily ignore. . .

That doesn’t apply to the Raptor. It can’t be ignored, as it has an irresistible slow-motion-train-wreck quality about it!
 
pilotrick said:
A deep stall has only been recoverable once and that was in a long ez piloted by Mike Melvill who admits he was lucky to be alive. He was testing the aft CG of the long ez.
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Technically, that's not 100% true. If you were to say "has only been recoverable once by control inputs". ;)

During deep stall testing Velocity installed an electrically driven sled with weights on it that allowed the CG to be moved beyond the aft limit. That allowed the airplane to enter a deep stall. Then after testing recovery techniques, the sled was moved forward and the plane came out of the deep stall.
 
donjohnston said:
Technically, that's not 100% true. If you were to say "has only been recoverable once by control inputs". ;)

During deep stall testing Velocity installed an electrically driven sled with weights on it that allowed the CG to be moved beyond the aft limit. That allowed the airplane to enter a deep stall. Then after testing recovery techniques, the sled was moved forward and the plane came out of the deep stall.
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Now that sounds like something someone serious about developing a new aircraft would do.
 
Tantalum said:
bUt a CaNArD pLaNe CaN'T StaLl

View attachment 93594

I'm sure he assumes his superior aeronautical skills guarantees that the canard will stall before the main wing and not require any actual testing on that front. Didn't a guy somewhere in a canard plane die because the main wing stalled first? I think a heavily modified Velocity? Or am I making this up
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Velocity had some deep stall issues early on but were rectified with a more conservative aft CG restriction and adding vortilons. A very interesting story below. At least I know if I do a water landing, she’ll float for a bit.
https://www.aopa.org/news-and-media/all-news/1996/june/pilot/pilots-(6)

Peter’s arrogance is showing again with his reasoning for not doing stall testing. He has no idea what his aircraft will stall at, if it’ll pitch buck, if it’ll be controllable or if it’ll stall lower than the allowable critical AoA of the main wing. The simple fact that he predicts it to stall around 80 kts is insane. Thing stalls around King Air / Citation I/II speeds but has yet demonstrated any cruise over 145 kts in level flight. Not to mention, touching down at 90 kts with no prop reverse, won’t inspire short field landing performance. He’ll never get the runway distances he’s advertising.

While his lift to drag ratio will probably be quite good as most canards are, in a low altitude engine out (below BRS) you’ll be going through the tress with a lot of impact forces. 55 kts in say an RV vs 85 kts in a Raptor is a world of difference in survivable outcome.
 
While I agree that he should have already done extensive stall testing, low speed landings, high speed runs, long cross countries, and more. Hating anyone because you don't agree with how they are developing their own plane, seems ridiculously harsh. On the entire planet I only hate 3 people, and they made it very personal, lied, and did evil things. Unless someone made it very personal and they made up stuff to attack me, I couldn't hate them. Sure I might disagree with them some, but certainly not anywhere near a level even approaching hatred. Even though I have disagreed with some people on this forum, I don't hate any of them. In fact I actually admire them for standing up for what they believe in, all except for one guy, who is so stupid, so arrogant, and spouts off like only his opinion matters, that guy I just think is too stupid to ever have a reasonable conversation with. Which actually makes me feel a bit sad for him, because I bet his life is rather miserable, and he probably doesn't even have one truly great friend in his life that would do anything for him, because he has ****ed off almost every person he meets...but I don't hate him, never even met the guy.
 
OneCharlieTango said:
Hate-wise, he’s nowhere near where Jim Bede was in his heyday, or Jim “Zoom” Campbell when he was suing members of rec.aviation.homebuilt. On YouTube, there are other contenders today. I’d start a “Who’s the worst Youtuber?” thread, but there’s no use dwelling on stuff you can readily ignore. . .

That doesn’t apply to the Raptor. It can’t be ignored, as it has an irresistible slow-motion-train-wreck quality about it!
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I'd say Jan Eggenfellner inspires a lot more hatred than he does as well. Although his Viking engine product has made a lot of people forget about his Subaru days.
 
3393RP said:
I couldn't find any information about modifications, but the NTSB report stated the airplane CG was about three inches beyond the aft limit. It's my understanding that a stall in this situation is pretty much an unrecoverable event.
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Here's a writeup by Marc Zeitlin, who inspected the plane a short time before the crash: http://cozybuilders.org/N79ZR_Accident_Eval/index.html

It's all interesting, but this is the part about the mods:
COZY aircraft N79ZR had been stretched 8" between the canard and main wing by the original builder (not Mr. Khan) and had only a rough estimate for CG range recommendation (I was assisting Mr. Khan with this task and was having extreme difficulty getting accurate information from him, as well as getting him to understand all the issues). It also had a substantially stretched nose forward of the canard, which, with the extra width of the COZY aircraft over the Long-EZ aircraft, was especially problematic at high AOA's with respect to deep stall (and stability, but that wasn't the problem here).

This aircraft had two sets of fuel tanks - standard strake tanks about 6" aft of the theoretical CG range (due to the forward move of the CG range from the stretch) and a smaller fuselage tank approximately 20" - 25" FORWARD of the theoretical CG range. Managing CG position in this aircraft would involve a large pilot workload and the calculations of both theoretical CG range and actual CG position were not well formed. With a forward tank so far from the acceptable CG range, burning fuel from the forward tank would move the CG aft very quickly. We do not know from where fuel for the flight was drawn, but we know that Mr. Khan (from airport records) had either topped off the tanks or come close to doing so before the flight.
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Also interesting that the pilot was wearing a parachute and was trying to bail, but apparently hit his head on the canopy or something, rendering him unconscious before the impact.

Zeitlin also appeared in one of Peter's videos. I believe Wasabi required Peter to hire him to inspect the plane. If you read his conclusions in that article, written long before he ever met Peter or laid eyes on Raptor, several of them sound like they're directed at Peter specifically.

Conclusions:

As aft CG and lack of vortilons are two large contributors to deep stall susceptibility (and have factored into at least one previous COZY deep stall incident, in 1996), Mr. Khan's decisions not to install the required vortilons and to stall test an airplane in which the CG range (and CG position) was poorly understood and controlled were not good ones.

So there is little new to learn from this accident - really, all we can learn are things we should already know, but I'll reiterate them here:
  • Understand and carefully determine the Acceptable CG range for YOUR aircraft (particularly if it's in ANY way non-standard)
  • Understand the CG location for YOUR aircraft on ALL flights - ensure that you are ALWAYS inside the approved AND TESTED CG range
  • Install all required aerodynamic safety items, including the vortilons, lower winglets, etc.
  • Understand the effects of fuselage stretch (or width increase), both between the lifting surfaces and forward of the canard, and approach any change of this nature with EXTREME caution
  • Listen to knowledgeable people when they give you solicited (or even unsolicited) advice regarding safety (where "Listen" means "act on it", not just "nod your head and ignore it")
  • Be extremely careful when making (or accepting previously made) aerodynamic and/or structural changes to ANY aircraft that were not approved by the designer - do not think that "it will be OK" merely because you want it to be
  • Do not fall into the "sunk cost" fallacy - just because you've thrown a lot of time and/or money at an airplane project doesn't mean that the right answer is to keep doing so, if there are major problems with it
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donjohnston said:
During deep stall testing Velocity installed an electrically driven sled with weights on it that allowed the CG to be moved beyond the aft limit.
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That's very clever.. and shows what a competent flight test program looks like.
 
Tantalum said:
That's very clever.. and shows what a competent flight test program looks like.
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I'll defer to your expertise. Tell us a little about the FMEA on it.

Nauga,
and the rush to judgement
 
nauga said:
I'll defer to your expertise. Tell us a little about the FMEA on it.
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I don't understand the defense for PM? Would I be elevated to "respected aircraft builder" (or at least some degree of "most hated aircraft builder") if I took a few months off work and hobbled together a plane?

Earlier I made the analogy of the idiot building the plywood rowboat vs the expert crafting a lapstrake canoe.. the insinuation that the person in the car watching both is the bigger idiot of the two.. I don't understand why. That's where our disagreement comes from.. just because someone does something doesn't make them an expert, in my opinion. I don't become a dentist by grabbing the dremel and trying to fix my own cavities. I'd sit in my car in home depot because I know I can't build a beautiful lapstrake canoe and don't want to waste my time building an ugly rowboat. If I instead went in home depot and built said ugly rowboat but proclaimed to be the best boat expert out there I'd be right to be ridiculed for that, especially if my boat leaked and didn't perform anywhere in the realm of how I advertised it would


On a separate note: It's clear you have a depth of experience with aircraft design, testing, and construction. It would be interesting to hear (rather, read) an objective review of what he's done right, what could be done different, and just an overall synopsis of the project as a whole. From the outside people like me, and I suspect many on this forum, have a somewhat "filtered" view of aircraft design.. only seeing what gets put out in a press release or what was written later in a book or magazine.. so it would be interesting to hear that take
 
donjohnston said:
Not sure how he would have that information.

But I can get more info if you're interested.
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It was a comment on his deeming it a competent test program based on a single sentence about the CG management system. I don't believe he has the information either. I *do* believe Velocity had a comprehensive test program, but I base that opinion on more than their CG management system.

If you have more info I'd be interested, particularly on failure modes and/or backup. I've worked with a few different CG management systems; and electrical systems, at least simple ones, tended to be higher risk than others (e.g. fuel transfer/dump) because (a) they tend to be slow for large weights or long travel, and (b) it's more difficult to get redundancy, or at least graceful failures, than with others. That doesn't mean they don't work, or even that they're "bad," but the risks are not always as apparent as the benefits. Sometimes you make the best with what you can do at reasonable cost and manageable risk.

Nauga,
with fuel in the stabs
 
nauga said:
I'll defer to your expertise. Tell us a little about the FMEA on it.

Nauga,
and the rush to judgement
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I've never played quarterback in the NFL, and I haven't watched an NFL game in years, but I can confidently state Tom Brady's replacement isn't very good.
 
Tantalum said:
I can't build a beautiful lapstrake canoe and don't want to waste my time building an ugly rowboat.
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Nonsense. You certainly could. You probably could on your first try. I've seen people who have to learn how to use simple hand tools build very nice airplanes on their first try. The key factor is, learn what you can and don't just look at something and think, "Well, that ought to be about right, I think..."

The same holds true for airplanes, of course.
 
DaleB said:
Nonsense. You certainly could. You probably could on your first try. I've seen people who have to learn how to use simple hand tools build very nice airplanes on their first try. The key factor is, learn what you can and don't just look at something and think, "Well, that ought to be about right, I think..."

The same holds true for airplanes, of course.
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.. and that's why I don't understand why we're not allowed to question Peter's ridiculous methods..
 
nauga said:
It was a comment on his deeming it a competent test program based on a single sentence about the CG management system. I don't believe he has the information either. I *do* believe Velocity had a comprehensive test program, but I base that opinion on more than their CG management system.
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..and I don't base that off a single sentence either..

Your tone suggested that Peter's testing program (or well publicized lack thereof) is equivalent to Velocity's, and that because I might not know some obscure data point I have no right to discuss it

One need not be a fireman to recognize a burning building..
 
..now I want to go build a boat..
 
What’s Peter’s background anyway? Any other experience in aircraft design or aircraft testing?
 
Tantalum said:
Your tone suggested that Peter's testing program (or well publicized lack thereof) is equivalent to Velocity's, and that because I might not know some obscure data point I have no right to discuss it
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My tone was intended to suggest that you have faired a curve through a single (anecdotal) data point and extrapolated a conclusion to support your preconceived notion. I pass no judgement on your *right* to discuss it, just as you should pass no judgement on my *right* to discuss what I see as flaws in your "analysis."

Nauga,
in engineering terms
 
3393RP said:
I've never played quarterback in the NFL, and I haven't watched an NFL game in years, but I can confidently state Tom Brady's replacement isn't very good.
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A couple years ago I heard a sportscaster refer to Johnny Manziel as a “free agent quarterback”. Considering the unlikelihood that he would ever play in the NFL again, I started describing my self as a free agent quarterback. :)
 
Our favorite innovator decided to read the manual and learned that his engine has a goofy thermostat with some electronic control. Better late than never.

And he's blaming people in the comments for not telling him about it. If someone had happened to know about it and told him, he'd most likely have blown them off and called them a mansplainer.
 
Don't forget the most hated aircraft builder also had some fun with cutters, sheet metal and tape! Sadly he left us with a cliff hangar ending and won't let us know if the cooling is fixed. Place your bets here!
 
231TC said:
Our favorite innovator decided to read the manual and learned that his engine has a goofy thermostat with some electronic control. Better late than never.

And he's blaming people in the comments for not telling him about it. If someone had happened to know about it and told him, he'd most likely have blown them off and called them a mansplainer.
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:lol::lol::lol::lol::lol:
 
pilotrick said:
Don't forget the most hated aircraft builder also had some fun with cutters, sheet metal and tape! Sadly he left us with a cliff hangar ending and won't let us know if the cooling is fixed. Place your bets here!
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You can tell from the tone of his voice that he thinks it's fixed. I doubt it really is, but I've been wrong a time or two. Either way, it will make a significant difference. Now maybe he'll be able to climb high enough to figure out his turbos won't work the way he thinks. And maybe even reconsider stall testing.
 
He won’t know if it’s fixed until he has a long taxi and takeoff on a 98 degree day.
 
nauga said:
It was a comment on his deeming it a competent test program based on a single sentence about the CG management system. I don't believe he has the information either. I *do* believe Velocity had a comprehensive test program, but I base that opinion on more than their CG management system.

If you have more info I'd be interested, particularly on failure modes and/or backup. I've worked with a few different CG management systems; and electrical systems, at least simple ones, tended to be higher risk than others (e.g. fuel transfer/dump) because (a) they tend to be slow for large weights or long travel, and (b) it's more difficult to get redundancy, or at least graceful failures, than with others. That doesn't mean they don't work, or even that they're "bad," but the risks are not always as apparent as the benefits. Sometimes you make the best with what you can do at reasonable cost and manageable risk.

Nauga,
with fuel in the stabs
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I see the point you were trying to make now. I suppose he should have stated "That's very clever.. and shows what a competent flight test program might have done."

Would that also have drawn a snarky response?
 
Jeff767 said:
He won’t know if it’s fixed until he has a long taxi and takeoff on a 98 degree day.
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As long as he stays in S GA, his wait won’t be long!

This is apparently an inherent problem to overcome in any pusher design - pretty obvious as there’s no “fan” out front to enhance cooling while stationary or at low speeds.

My plane tries to mitigate this with two small electric fans that force some small amount of air through the oil cooler and radiator. With no great success on the very hottest summer days. With an extended hold on a hot day, the best plan is to temporarily shut down while holding.
 
It rarely if ever hits 98 in South Georgia. It only feels like it’s 108.
 
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Getonit said:
He still says some wacky things that don’t make sense.....but the airplane does look more stable.
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From what I saw, it seems to oscilate like you're in a rocking chair.
 
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Kevin Eggert said:
From what I saw, it seems to oscilate like your in a rocking chair.
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If you could superimpose the first flight video with the most recent one, the stability improvement would be more obvious.
 
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