10/23 Raptor Video

[Voidhawk9]

why doesn't he find out how slow his plane can fly so he can dial back the speed some?

There is a problem with pitch stability. You can see this as the pitch angle moves up and down 5deg or so back and forth quite a bit. This isn't turbulence, it's wallowing around. When he gets it trimmed nice and stable it will stay there, but if disturbed, it's back to unstable wallowing again.
I'm pretty sure at this stage that he's too scared to fly it to an actual stall because there's a good chance it'll deep stall and he'll have to pull the chute, and write the machine off.
If that happens, it's game over.

 

[BBerson]

Approach speed is 1.3 times stall at his current max weight. Until he gets to 8000 feet for the stall tests he needs to approach at 100 and touch around 90, I think he said. Probably also wants a shallow angle to prevent dropping in hard with a possible prop strike.
The Citation has big flaps and thrust reverse and can land on a 3000 ft. runway.

 

[Mark Z]

TRs aren’t figured in on landing distances. The only reason they’re there is to let everyone know you’ve arrived.

 

[donjohnston]

Approach speed is 1.3 times stall at his current max weight. Until he gets to 8000 feet for the stall tests he needs to approach at 100 and touch around 90, I think he said. Probably also wants a shallow angle to prevent dropping in hard with a possible prop strike.
The Citation has big flaps and thrust reverse and can land on a 3000 ft. runway.

 

[donjohnston]

Until he gets to 8000 feet for the stall tests he needs to approach at 100 and touch around 90

8,000' to do stall tests??? I did mine at 3,000'... On the first flight (So I would know what speed to land at).

 

[BBerson]

8000 was the number on Marc's website. I am guessing you were not testing a new design at max weight and had adequate prop clearance.

 

[Bill-Higdon]

TRs aren’t figured in on landing distances. The only reason they’re there is to let everyone know you’ve arrived.

 

[donjohnston]

8000 was the number on Marc's website. I am guessing you were not testing a new design at max weight and had adequate prop clearance.

No, I was not testing a new design. Not sure what prop clearance has to do with stall testing.

I can't see how another 5,000' of altitude will make any difference in testing when the canard stalls. If, for some reason, it gets into a deep stall, you'll just have longer to think about it.

 

[Vigilant1]

Only a deep stall is possible? I don't think anyone watching that plane bobbing around in "level flight," and noting the weight that has been added since it was designed, can say what will happen when one or both flying surfaces exceed the critical AoA. In a situation like that, and with an untested ballistic chute, having altitude is better than not having it.

 

[Voidhawk9]

Only a deep stall is possible?

No, but given the aircraft behaviour, it appears the relationship between the canard and the wing is already wrong, so a deep-stall is more likely.

 

[BJC]

I can't see how another 5,000' of altitude will make any difference in testing when the canard stalls. If, for some reason, it gets into a deep stall, you'll just have longer to think about it.

I don’t have any canard or deep stall experience, but I have done thousands of spins of all types. When doing such testing, altitude gives time to apply all known recovery techniques, admit failure, and then execute a timely bail out.


BJC

 

[malte]

Not sure what prop clearance has to do with stall testing.

I think that was a euphemism for the necessary altitude you need to have while stall-testing a new design.

I can't see how another 5,000' of altitude will make any difference in testing when the canard stalls. If, for some reason, it gets into a deep stall, you'll just have longer to think about it.

If you have an airframe chute, it can make a huge difference to have time to pull.


FWIW we always plan to have the test finished (including one failed attempt to end a spin) in 5000AGL.

 

[rbarnes]

No guarantees with that airframe chute. Rear prop, never tested deployment, and never tested whether the attach points would hold.

 

[BBerson]

Not sure what prop clearance has to do with stall testing.

He doesn't have much prop clearance. So touchdown in a nose high attitude near stall isn't an option. No need to prioritize stall testing just yet.

 

[Vigilant1]

He doesn't have much prop clearance. So touchdown in a nose high attitude near stall isn't an option.

That won't change after he knows where the stall is. As long as the weight, wing incidence, wing Cl, prop length, and gear length remains unchanged, it seems to me that Peter and any customers will need to keep landing at these speeds.

 

[Wanttaja]

Does the Raptor actually have a ballistic chute? I thought one had been planned, but not installed yet.

Ron Wanttaja

 

[BBerson]

That won't change after he knows where the stall is. As long as the weight, wing incidence, wing Cl, prop length, and gear length remains unchanged, it seems to me that Peter and any customers will need to keep landing at these speeds.

Right. But changing any of those is unlikely on the R&D ship. It's assumed purpose is to be for whatever research, experimentation and development is needed for a customer prototype.

 

[donjohnston]

He doesn't have much prop clearance. So touchdown in a nose high attitude near stall isn't an option. No need to prioritize stall testing just yet.

I only have experience in Velocity's, but I assume LongEZ's, Cozy's, etc. all land the same way. Relatively flat. I'm on the ground at least 5kts over the canard stall speed. Try to cut it too close and you could have the canard stall while you're still 5' off the ground. That's a bad place to be stalling the canard.

So if the prop doesn't hit the ground on takeoff, it's unlikely to to hit on landing.

 

[rbarnes]

Does the Raptor actually have a ballistic chute? I thought one had been planned, but not installed yet.
Ron Wanttaja

 

[Kyle Boatright]

That won't change after he knows where the stall is. As long as the weight, wing incidence, wing Cl, prop length, and gear length remains unchanged, it seems to me that Peter and any customers will need to keep landing at these speeds.

If the engine fails at 500', whoever's flying one will be VERY interested in minimum flight speed for the off-airport landing. 500' is probably out of the envelope (low) for the airframe 'chute.