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10/23 Raptor Video

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BJC

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Delmar Benjamin flew the GeeBee R2 Replica inverted and checked the stall speed on its maiden flight on December 23, 1991..
Two considerations:

Delmar was MUCH more experienced in aerobatics than Raptor guy is.

When asked why he did all those maneuvers on the maiden flight, Delmar reportedly said that he wanted to fully experience flying the airplane, in case he wrecked it on landing.


BJC
 

flywheel1935

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Raptor Aircraft
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Technically it won't stall. It just won't let you fly slower than about 80 knots and even then you will be descending about 200fpm. We'll find out when I get to that point. However, adding flaps and converting the ailerons to flaperons is something that is planned.

This is a reply from the latest YT video, Add weight and even more complexity !!!,that's the way to build aircraft for the 'homebuilder', It can't end well :-

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PPLOnly

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5 minutes ago
Technically it won't stall. It just won't let you fly slower than about 80 knots and even then you will be descending about 200fpm. We'll find out when I get to that point. However, adding flaps and converting the ailerons to flaperons is something that is planned.

This is a reply from the latest YT video, Add weight and even more complexity !!!,that's the way to build aircraft for the 'homebuilder', It can't end well :-(
I’ve never flown a canard, does the nose stall and drop or the whole aircraft just kind of drift down at stall speed?
 

Voidhawk9

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I’ve never flown a canard, does the nose stall and drop or the whole aircraft just kind of drift down at stall speed?
Designed and operated correctly, the canard does stall, but not the main wing. This causes the nose to lower.
If not designed or operated correctly (ie W&B out of range), the main wing can stall first, resulting in a pitch-up and potentially unrecoverable deep-stall.

Which kind Raptor exhibits, we do not know.
 

rv6ejguy

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Peter finally admits that his oil cooler fed by hot cowling air doesn't do much. No surprise there as I pointed out earlier, wondering why he even bothered. Sounds like he's revised the inlet to be fed by ambient air now. We'll see what he's done on the next vid. He also finally admits that's it time to fix the cooling as he can't climb at more than 50% power for any length of time in these relatively cool conditions.

He says he feels more confident that nothing bad will happen. Complacency creeping in. He better have a plan when something does happen, especially as he moves the power and speed up in future.

What seemed extra evident in this flight was the constant cyclical rolling motion we've seen before. If you watch carefully from in cockpit, you can see it's yawing as well at the same frequency so this appears to be Dutch Roll.
 
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Marc Zeitlin

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I’ve never flown a canard, does the nose stall and drop or the whole aircraft just kind of drift down at stall speed?
There are a few different modes of stall. The standard one is as @Voidhawk9 states - as the elevator deflects more, the canard will stall but the main wing will remain flying. The nose will drop a few degrees, the canard will drop below the critical stall angle, and it will rise back up a few degrees. This "bobbing" will occur with full roll control - I've performed stalls in a 60 degree bank in my COZY MKIV, and can climb at over 600 fpm while stalled with application of full power, with the nose bobbing all the while. It's somewhat disconcerting.

Another common mode, particularly at forward CG's, is a "mush" - the canard stalls, but doesn't bob - it just stays stalled at one AOA, with the main wing still flying as before. All other characteristics are about the same as in the "bob" mode.

The "deep stall" to which @Voidhawk9 refers will occur if the incidence angles of the canard and wing are not correct with relation to one another or if the CG is far enough aft that the main wing can stall either during an upward bob of the canard or even before the canard stalls. In this case, IAS will drop off quickly and the aircraft (at least Velocities, COZY's and Long-EZ's) will settle into an approximately level attitude with respect to the horizon, but will be descending at about a 45 degree AOA and flight path angle. This is a VERY stable condition and is VERY difficult to get out of - there is only one known recovery in these aircraft from a deep stall, which I'll discuss below. The descent rate and the forward velocity are approximately equal in a deep stall, at about 45 mph both forward and down, give or take. You can see an analysis of a fatal deep stall accident of a heavily modified COZY MKV here:


although what was fatal was NOT the impact with the ground (or in this case, water) of the aircraft.

Now, just because it's a great story, the only deep stall recovery was effected by Mike Melvill in his Long-EZ, while testing very aft CG (3" aft of the rearmost limit) operation. He entered the deep stall (which surprised him how quickly the IAS bled off and the airplane became rock stable) at about 13k ft. AGL. After attempting recovery with elevator, aileron and throttle input and having essentially no useful response, he started oscillatory rudder input, and due to the coupling between roll and yaw in the aircraft was eventually able to "pump" the rolling motion enough so that the plane went over the top, started a dive, and he was able to then recover at about 1K ft. AGL above the Stater Bros. supermarket in Mojave. All other deep stalls have resulted in the airplane impacting the ground or water. An inverted Velocity deep stall was fatal - the other than N79ZR) COZY MKIV deep stalls resulted in moderate injury to the pilot(s).
 

Turd Ferguson

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- I've performed stalls in a 60 degree bank in my COZY MKIV, and can climb at over 600 fpm while stalled with application of full power, with the nose bobbing all the while. It's somewhat disconcerting.
So it's possible Raptor's climb rate could improve substantially if he would climb in a stall........ ;)
 

Voidhawk9

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Interesting that he now admits the cooling isn't working. And that his landings are a bit crazy.
Also that he is now considering a wind-tunnel model (after the west coast move). Albeit to solve the non-problem of canard vortices.
 

Victor Bravo

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At the 4:00 or so mark in the latest video, he says something about putting a small fence near the static port, that is driving air into the hole, giving him lower altimeter settings or lower airspeed, or something along those lines. Then he says that's "going in the right direction".

Please forgive my catastrophic lack of education and intellect, but intentionally creating incorrect pressures at the static port, bringing all pitot-static related readings into question... is going in the right direction??!!??
 

berridos

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Maybe a solution to dutch roll could be to place a large fence right where the canard vortice hits the main wing.
 

wsimpso1

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At the 4:00 or so mark in the latest video, he says something about putting a small fence near the static port, that is driving air into the hole, giving him lower altimeter settings or lower airspeed, or something along those lines. Then he says that's "going in the right direction".

Please forgive my catastrophic lack of education and intellect, but intentionally creating incorrect pressures at the static port, bringing all pitot-static related readings into question... is going in the right direction??!!??
While the ideal world static port location is a spot that reflects true static over the entire flight envelope, many planes have achieved acceptable solutions with fences, steps, and other manipulations of the air near the static port. I do like the idea of simply programming the display with corrections for altitude and true airspeed, but no one is doing that ... yet.
 

wsimpso1

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Maybe a solution to dutch roll could be to place a large fence right where the canard vortice hits the main wing.
Maybe. Probably more than one solution out there, and the big questions are to up side (effectiveness) and downside (drag, weight). I am skeptical that this is due to vortices off the canard, as other canard ships are very similar in canard-wing arrangement and do not have axis coupling issues.

There are already proven solutions for unwanted axis coupling in place on other canard aircraft. Seems that would be an efficient starting point.

At one time I called the roll-yaw-pitch oscillation we are seeing "Dutch Roll", but the point was well made that Dutch Roll mode has slip figuring prominently, with the Ball sliding back and forth. Raptor's mode keeps the Ball centered (indicating coordination is maintained). Maybe it gets labeled Mueller Mode? The FPV shows the airplane moving in all three axes together. This suggests to me that it has plenty of yaw centering but pitch and roll want to wander together. Maybe airframe, maybe pilot interaction on the stick.

Billski
 

Toobuilder

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I'm amazed how long this guy will cling to an idea and try force it to work. I have tried and abandoned some things on my airplanes that "seemed" like good ideas, but didnt work in practice. My unconventional oil cooler duct is an example - didnt work out of the box, and now that I've thrown so many fixes at it to "make" it work, it no longer meets the original design goals. Instead of being a "clever" solution, now its just weird.

At some point, a designer needs that moment of clarity and admit his good idea...

...isnt very good!
 

Pops

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Friend of mine and next door hanger neighbor had a Cessna 411 for a short time. I got to fly it one day and it did the same thing. In smooth air and hands off the wheel there was a constant oscillation in pitch and roll. I told him that it was the worse airplane I have ever flown and he said you sort of get used to it. Loved the old Beech 18 he had for about 20 years.
 
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