Raptor Aircraft

donjohnston said:
Yeah, Vx and Vy wouldn't be my top concern. Stall speed? That's be one of the first things I would test (and did).
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My own long ramble about buildup and troubleshooting deleted, but in summary if I had an airplane that had the characteristics he's demonstrated *above* stall speed *and* I couldn't reliably get it above 6K feet I wouldn't be leaping headlong into (low altitude) stall testing. I'd poke at the low speed end and pick an indicated approach speed with margin above the lowest speed I tested satisfactorily and work with that until I got the heart-of-the-envelope handling and propulsion worked out. I may have, just maybe, even done that once or twice.

I don't know whether Raptor dude is doing that or not, but there can be reasons for not doing stalls early.

Nauga,
who also answers to 'Max Flex'
 
With the performance that he's getting, would he indeed get a permit to fly it to CA?
 
WDD said:
With the performance that he's getting, would he indeed get a permit to fly it to CA?
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I'm not sure the FAA considers that. Who are they to judge the capabilities of a non-certified airplane? I would think a ferry permit (or however it would be deemed) would be more of an administrative process.
 
nauga said:
My own long ramble about buildup and troubleshooting deleted, but in summary if I had an airplane that had the characteristics he's demonstrated *above* stall speed *and* I couldn't reliably get it above 6K feet I wouldn't be leaping headlong into (low altitude) stall testing. I'd poke at the low speed end and pick an indicated approach speed with margin above the lowest speed I tested satisfactorily and work with that until I got the heart-of-the-envelope handling and propulsion worked out. I may have, just maybe, even done that once or twice.

I don't know whether Raptor dude is doing that or not, but there can be reasons for not doing stalls early.

Nauga,
who also answers to 'Max Flex'
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Have you actually looked at his flight profiles in flight aware?
 
nauga said:
My own long ramble about buildup and troubleshooting deleted, but in summary if I had an airplane that had the characteristics he's demonstrated *above* stall speed *and* I couldn't reliably get it above 6K feet I wouldn't be leaping headlong into (low altitude) stall testing. I'd poke at the low speed end and pick an indicated approach speed with margin above the lowest speed I tested satisfactorily and work with that until I got the heart-of-the-envelope handling and propulsion worked out. I may have, just maybe, even done that once or twice.
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Stalls on a canard are much less eventful than on a traditional aircraft. Even on one as poorly thought out as this one. And I would want to know how slow I can fly should I have to land off airport.

nauga said:
I don't know whether Raptor dude is doing that or not, but there can be reasons for not doing stalls early.
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I don't consider 20+ hours of flight "early". At what point would you consider determining the stall speed of the canard? He's already at the point where I finished Phase I testing and he hasn't tested... anything.
 
donjohnston said:
I don't consider 20+ hours of flight "early". At what point would you consider determining the stall speed of the canard? He's already at the point where I finished Phase I testing and he hasn't tested... anything.
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In fairness, he has been testing a few things including the powerplant reliability and what probably amounts to cruise performance. While he hasn’t published any numbers, he has also certainly put some fuel into it to get this far and has a better idea of fuel consumption in climb and cruise.

He has also demonstrated that his powerplant is capable of putting a plane in the air and keeping it there for a couple hours. If he has financial resources for it, there is every reason to think that he could build a second prototype around the same basic engine and propeller drive, but with better flight controls and cooling designed in from the beginning and a lower empty weight when it starts flying.
 
donjohnston said:
Stalls on a canard are much less eventful than on a traditional aircraft. Even on one as poorly thought out as this one. And I would want to know how slow I can fly should I have to land off airport.
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It looks like you and I are conservative in different areas. I'm reluctant to poke around the left side of the flight envelope in an airplane that has demonstrated issues in the heart of the envelope, and tend to mitigate that as outlined earlier; however, there are no absolutes, and there are advantages to either approach.

donjohnston said:
I don't consider 20+ hours of flight "early". At what point would you consider determining the stall speed of the canard? He's already at the point where I finished Phase I testing and he hasn't tested... anything.
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I'd consider determining the stall speed once I was comfortable with the general flying qualities, was convinced the airplane would be recoverable, and I could get to an altitude sufficient to recover or get out if I was wrong on the first two points. This is not a comprehensive list, especially for a new design. As for the last sentence, I disagree. He may not have been testing what you or I tested or would test or in a reasonable and methodical manner, but he has been testing.

Nauga,
pressing to test
 
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I don’t blame him for not wanting to stall just yet. It’s barely flying and spends most of its time close to the ground. Frankly I figure he must waddle around because his balls get in the way. That propulsion package is a grenade. I wouldn’t fly it at all. Whatever, it will be what it is and I hope he comes through it ok.
 
kyleb said:
I think from an administrative standpoint, he'll be able to get his operating limits expanded for a flight to California. Apples and oranges, but i remember a major kit manufacturer which got a 10 mile wide x very long test area mapped out and approved to fly their EAB from the West coast to either Oshkosh or Snf, prior to finishing the 40 hour test period. They may have completed the fly-off enroute...
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there is a big difference between a major kit manufacturer with a long track record and has a known reputation with their POI, and peter.
 
Despite what Peter says, I don’t think he feels confident in stalling it. He doesn’t have much flying experience, especially in canards. Other than stalling at a ridiculously high speed, I don’t think I’ll exhibit and poor handling characteristics. With all the gripes the Wasabi guys brought up, there wasn’t any concern about the canard stall characteristics.

Personally, I would’ve done a stall on the first flight. Pretty important to get an idea of when a canard stalls in order to judge proper touchdown speed and the proper attitude that goes with that speed. By skipping that test point, all Peter did was come in hot to make up for not having a clue about landing speed. His porpoising in the flare in quite evident because of that. In the canard community those who haven’t adhered to proper speed on final has resulted in some damaged landing gear...including mine. :(
 
Velocity173 said:
Personally, I would’ve done a stall on the first flight.
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Of this particular airplane with the performance that has been documented to date? At what altitude and how would you get there?!

Nauga,
who wouldn't smoke a motor just to get a stall done
 
Velocity173 said:
Despite what Peter says, I don’t think he feels confident in stalling it. He doesn’t have much flying experience, especially in canards. Other than stalling at a ridiculously high speed, I don’t think I’ll exhibit and poor handling characteristics. With all the gripes the Wasabi guys brought up, there wasn’t any concern about the canard stall characteristics.

Personally, I would’ve done a stall on the first flight. Pretty important to get an idea of when a canard stalls in order to judge proper touchdown speed and the proper attitude that goes with that speed. By skipping that test point, all Peter did was come in hot to make up for not having a clue about landing speed. His porpoising in the flare in quite evident because of that. In the canard community those who haven’t adhered to proper speed on final has resulted in some damaged landing gear...including mine. :(
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That’s a bold statement there Cotton.
 
nauga said:
Of this particular airplane with the performance that has been documented to date? At what altitude and how would you get there?!

Nauga,
who wouldn't smoke a motor just to get a stall done
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Being a canard, his altitude loss in a full stall would be marginal. One pitch buck would lose maybe 100 ft. At the very least, pull the power back do a little slow flight on downwind to an approach stall. Just as recommended here on first flights.

http://iflyblog.com/first-flight-flight-testing-your-experimental-aircraft/

https://www.eaa.org/eaa/aircraft-bu...cles/stage-two-making-the-initial-flight-test
 
FastEddieB said:
I know little about canards, but I've heard of deep stalls. Is that not a concern in the Raptor, and if not, why not?
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Deep stalls were only a problem for early Velocities. It was resolved with vortilons on the leading edge of the wing. Peter would have to have seriously miscalculated the angle of incidence of the canard vs the main wing get into a deep stall.

http://wiki.velocityoba.com/index.php?title=Deep_stall
 
Velocity173 said:
Being a canard, his altitude loss in a full stall would be marginal. One pitch buck would lose maybe 100 ft. At the very least, pull the power back do a little slow flight on downwind to an approach stall. Just as recommended here on first flights.
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*Should be* marginal, but I'm not going to bet my life on it by finding out at low altitude. I am maybe just a tad more conservative than you appear to be with a new design that's got a whole host of unexpected problems. "It will probably be OK" is not a flight test risk mitigation.

Nauga,
who hopes for the best but prepares for the worst
 
nauga said:
*Should be* marginal, but I'm not going to bet my life on it by finding out at low altitude. I am maybe just a tad more conservative than you appear to be with a new design that's got a whole host of unexpected problems. "It will probably be OK" is not a flight test risk mitigation.

Nauga,
who hopes for the best but prepares for the worst
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Ever come close to pulling the handles?
 
Velocity173 said:
Peter would have to have seriously miscalculated the angle of incidence of the canard vs the main wing get into a deep stall.
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Or missed separation on the main wing, particularly outboard; or missed his stability margin estimates or CG; or...

I have no suspicion that there is a deep stall problem more than any other issue...but I'm not going to trivialize it.

Nauga,
and what lurks in the darkness
 
Velocity173 said:
Peter would have to have seriously miscalculated the……
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If it happened with the early velocities as you pointed out with their caliber of development, why do you think it isn’t a distinct possibility here?
 
WDD said:
If it happened with the early velocities as you pointed out with their caliber of development, why do you think it isn’t a distinct possibility here?
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Peter doesn’t make mistakes.
 
Tarheelpilot said:
I don’t blame him for not wanting to stall just yet. It’s barely flying and spends most of its time close to the ground. Frankly I figure he must waddle around because his balls get in the way. That propulsion package is a grenade. I wouldn’t fly it at all. Whatever, it will be what it is and I hope he comes through it ok.
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I think that you may be confusing testicular size with ignorance. or ego, Or stupidity. Or a number of other things.
 
nauga said:
He may not have been testing what you or I tested or would test or in a reasonable and methodical manner, but he has been testing.
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Okay, I'll bite. What has he been "testing"?

How many figure 8's he can do in one flight? How long it can fly? Because looking at the flight profile, that looks like all he is doing.
 
Velocity173 said:
Deep stalls were only a problem for early Velocities. It was resolved with vortilons on the leading edge of the wing. Peter would have to have seriously miscalculated the angle of incidence of the canard vs the main wing get into a deep stall.

http://wiki.velocityoba.com/index.php?title=Deep_stall
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Not just Velocities, but any Canard has that potential. Velocity I think is just the largest canard EAB (both size and numbers).

Tim
 
Seems the prize is getting "x" hrs logged at which point the project advances to the next stage with the West coast contingent. The next stage also seems to relieve PM of his duties so I can see why there is no interest in testing.
 
donjohnston said:
Okay, I'll bite. What has he been "testing"?
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Cooling and engine operability, for starters...but I believe that's been a while. I expect he's learning quite a bit about performance during current flights. There is testing benefit in simply putting time on a new airplane and finding problems - that's one reason there's a time limit specified in phase I oplims for EAB airplanes rather than just a checklist of data to collect. Whether he's actually doing anything with the data I can't say.

donjohnston said:
Because looking at the flight profile, that looks like all he is doing.
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What specific kind of test can you discern from a flight profile with no other data? Before anyone suggests "performance" tell me what the power setting and weight are. I can think of several things it *could* be, but in the absence of other data there is no way to tell. I expect he really is just running out the clock but that doesn't mean there's no value in it.

Nauga,
boring holes in the sky
 
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tspear said:
Not just Velocities, but any Canard has that potential. Velocity I think is just the largest canard EAB (both size and numbers).

Tim
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Well sure, any canard has the potential if the kit / plans aren’t adhered to but Velocity specifically had multiple aircraft with deep stall issues. Any new aircraft could exhibit poor handling characteristics. If Peter built a tractor config with a T tail, he could get into deep stall. That’s the whole point of flight test. You’re confirming that your performance / handling calculations are correct. You just can’t say, well, I’m fairly certain the aircraft will handle the way I predict, so let’s just skip stalls.

In Peter’s case, his flight testing, if you could even call it that, hasn’t even come close to his predictions. I guess since nothing has really gone right with this project, we should anticipate the worst but his one saving grace is his scale RC model. It never exhibited a deep stall. If anything, especially the first model, stalled at a very shallow AoA. Thing was bobbing around at almost cruise flight. Personally I think the aspect ratio of his canard is still too low. It’s creating high wing loading and enormous drag.

Peter is just boring holes in the air and accomplishing nothing right now. At the end of 40 hrs, he’ll still have an underpowered over weight aircraft...and still won’t know what she stalls at.
 
Lot of recent comments on stall speed. Did he fix the pitot-static system so the airspeed records relatively accurately?
 
How does one get out of a deep stall? Excess power? If power is the means to get a canard out of a stall, I'd be hesitant to stall the raptor as well.
 
woodchucker said:
Lot of recent comments on stall speed. Did he fix the pitot-static system so the airspeed records relatively accurately?
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I've only watched bits and pieces or summaries here, but don't remember it ever being mentioned.
 
Move the CG forward. When Velocity was testing this they built a sled with weights on it that they could move fore and aft. This allowed them to get the plane into a deep stall and then fly out of it.

Power wouldn't really help since the prop is mostly blocked by the angle of the fuselage.
 
donjohnston said:
Power wouldn't really help since the prop is mostly blocked by the angle of the fuselage.
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Well that'd be terrifying. Getting the plane into a situation where nothing you do can make it not crash. And with the raptor's doors and engine/prop back there, not sure if you could even bail if you had a parachute. I wouldn't want to stall it.
 
Post that in the thread of the person looking to become a test pilot... :hairraise:
 
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