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Discussion in 'Flight Following' started by Unit74, Nov 6, 2015.
Sorry if this is the 8,000th time this has been asked, but why is he flying right seat?
Believe that he said at some point he prefers the throttle in his left hand and stick in his right.
Because he's such an accomplished stick-and-rudder man, and that's the way he flew them in 'nam!
So when he crashes it, he can claim he wasn’t PIC.
Ah yes, the tried and true stolen car defense...
“The guy was just giving me a ride! I don’t even know him.”
Dude hasn't a clue about canard aerodynamics. This is like turning my 9 year old loose with gasoline and matches. It won't turn out well.
I found it odd that he’s trying to direct ram pressure into the <poorly placed> static port.
Not an aeronautical engineer, but it sure seems like that would trade airspeed reading high with increasing speed with exactly the inverse situation.
I would think it would cause altitude and airspeed to read lower as airspeed increases.
Static port location and shape are a bit of a black art unless you have a wind tunnel or some impressive software and fluid dynamics skill. In the E/AB world we depend on either prior builders or trial and error.
Even though my static port was exactly where the manual called it out to be, I was picking up about 200' and 20kts. Lots of testing resulted in this.
With the dam in back, my altitude error was down to about 30' (high) and airspeed 2kts (high). At low speed, it's accurate.
But putting a static port on the belly? That's the craziest thing I've heard (at least as far as static port placement goes). Unless you put a second one on top maybe.
Camber was the term he was looking for on the tire scrub. Camber and toe. Basic race car set up stuff that is apparently lost on this aviation genius.
To be fair, I think most of the A&Ps I work with could not explain those things well.
With artificially increased static pressure, indicated airspeed will read low. By putting the static port on the bottom of the fuselage, he should see static pressure going up with angle of attack. This will help lower the indicated airspeed at which the plane stalls. The Raptor Aircraft website claims a stall speed of 65 kts. The higher the static pressure at the stall, the closer the plane will be to living up to that claim.
The problem with the shim is that it appeared to be uniform thickness. If so, all that will do is exacerbate the excessive negative camber. (Think hub spacer on a car.) Considering that he's bolting this to a composite gear leg, I would recommend he use the thicker plate as a backing plate to distribute forces across a larger area of the composite gear let, and then cut the thinner plate in half and apply to the top bolts to introduce some positive camber to the wheel. A bubble level on the face of the wheel (vertically) will illustrate what change in camber he'll get from that.
It's not, it is wedge shaped. That's an aircraft spruce part that I recognize and have used on my own project ;
But it will also cause his cruise speed to indicate significantly lower than actual resulting in not hitting that claim.
That's nothing but a plumbing problem. He has enough static ports to choose from. He just needs a valve that can be used in flight to select between them. Pick the low-pressure static port for the service ceiling and cruise speed claims. Use the high-pressure-at-high-AOA static port for the stall speed demonstration. Switch between them after takeoff to help with the time-to-climb demonstration.
I was also surprised at the thinness and apparent flatness of the shim.
As delivered, my Sky Arrow had too much (I think) camber. As it sat, the tire rested on its outside edge. The theory was that the Light Sport version was enough lighter than the “certified” version that the gear did not flex enough under the aircraft’s weight. The factory fix was a shim, which as you can see below, which is far from subtle!
Anyway, the tires now sit pretty much perpendicular to the ground, and wear seems pretty even across the tire.
He’s anticipating the FAA adding “repetitive high speed taxi” to the PTS and wants to be ready to capitalize on the CFI demand?
On the static port issue, why not use one like the Pipers, with a pitot and static on the same device?
Mentioned repeatedly upthread. No one can think of a good reason why not.
Could an AGI give instruction on repetitive high speed taxiing?
For anyone not wanting to look upthread that far, this includes the fact that the plane already has that kind of combined pitot/static mast installed on it.
So all he has to do is to hook up the hose to the port on the pitot/static device, right? If so, it's puzzling why he hasn't done so already
Because he's a "cutting edge" guy. That static port on the pitot mast is old school. You gotta come up with something new and very complicated to get people to throw money at you.
Points to part on airplane, "No no no, you don't understand. We leveraged blockchain technology integrated with big data with an AI-adaptive front end to synthesize a full-stack solution to aviation's most persistent problem."
"What's it do?"
"Keeps **** off the seat cushion when you scare yourself."
and buzzword bingo
In fairness, if Jeopardy offered the clue “This 21st-century invention has a crowd of detractors and nobody really understands how it’s supposed to work but, according to many anonymous internet users, it is an extremely valuable, game-changing invention in its field,” would you respond “What is Raptor aircraft?” or “What is blockchain-based cryptocurrency?”
Each time the Raptor goes more than a few days without another high-speed taxi video I wonder if its been put into a ditch/crater.
He's doing "maintenance".
You look at guys like Peter and the guys at Celera. Peter posts a video every other day. Where the Celera... Well silence. There's 2 reasons guys like Peter post videos as frequently as he does. First, he needs the attention and to show people how much a visionary he is in his own mind. The second reason is for money. Either to drum up sales as a means for advertising or to keep investors reasonably at ease. Either way, it appears he doesn't have the bankroll to do it without external help. And his ego is such that he won't accept outside help. It's a bad bad combination. Just look at some of the youtube comments. Some very smart people giving him free advice. Wasabi guys listened to it. Now the Celera guys, the owner appears to have the bankroll to float his "hobby", at least a quick Google search makes it appear that way. That's what it is right now, a hobby. It may turn into a legit business. But Peter's goal of selling these as kits is an absolute pipe dream. I couldn't imagine what the plans would look like.
Peter is obviously a smart guy. Don't get me wrong. But there's a ton of stuff in regards to this project that he really needs to take a step back from and realize what he and the technology he's using is capable of. Mike Patey he is not. That dude is a freaking mad man. I don't think he even sleeps. He's got a twin brother so maybe he does. Theyre both nuts. He's got not only the knowledge and the skills but the attention to detail required to not kill yourself flying in a plane you designed. One thing you'll notice with Patey is his risk aversion. By that I mean he uses the PT6 extensively (exclusively?) They just don't fail. They're a known quantity. Peter has absolutely zero known quantities. Well, maybe the brakes and the tires were meant for aviation...
Mike Patey is an absolute craftsman with a solid understanding of actual true to life engineering. I don't see these qualities in Peter's build videos.
True. Mike is a legend.
While checking out the DA-50 specifications, I realized here is a way to inject some reality into PM's performance claims for the Raptor. But, since I'm not an aerodynamicist, I'm going to use a little common sense and some TLAR to make a point.
The two aircraft have similar powerplants; both are twin turbocharged diesels rated at 300 HP. Generally, one can expect that two aircraft roughly the same size and with the same amount of power will have similar maximum speeds. Now, obviously the two airplanes' configurations are radically different.
But while Diamond says the DA-50 has a max speed of 181 knots and a 20,000' ceiling, PM claims the Raptor has a top speed of 300 knots and a 25,000' ceiling.
While the ceilings will affect TAS, I find the 119 knot difference a bit hard to swallow. The Raptor's large fuselage, fat wings, and winglets appear to have more frontal area than the DA-50. Doesn't drag increase as the square of speed?
And how can the Raptor get another 5,000' of altitude with the DA-50s' same HP? Again, I'm not an expert, but it seems that would require the turbochargers to produce another 3 to 5 bar of boost.
Would someone with more knowledge than me care to comment?
On paper anything is possible.
Flow separation is the largest factor of drag for aircraft. Its the reason why many manufactures of fixed gear aircraft put those large aerodynamic covers around the wheels. Frontal area is how much air you need to separate, but if you can bring the air back together without the flow separating from the surface you are golden.
The Diamond is a thousand pounds heavier and has 10' more span. It is gonna be draggier than the <smaller> Raptor. Might be a better performer than the Raptor at altitude though, because of its span loading and aspect ratio.
Looking at it another way, the Diamond has flown and proven its performance. At this point, the Raptor is a paper airplane, and my paper always outperforms your proven design.
Besides, folks smarter than me over at Homebuiltairplanes.com have found some <apparent> huge mistakes in Peter's drag calculations and CFD (computational fluid dynamics) conclusions.
"Sometimes you have to trust the math"
Oh I do. It's the workmanship I don't trust.
Did you see his tagline?
“Everything is back together and the brakes are conditioned. Next up, taking it into ground effect.”
The math is telling Peter "Your airplane is 1000 lbs overweight and your engine can't cool at full power. By the way, you're not getting the 400 hp you're claiming."
Peter's response is "I'm OK with that."
The recent video which detailed his cooling system "testing" was more of Peter's faulty logic. The coolant temperature went up at full throttle, came down a little when power was reduced, and dropped some more at idle.
He showed his engine monitor traces, explained how they met his expectations, and concluded there was sufficient cooling capacity to fly the airplane. This is the same model he has used from the beginning. Some sort of 'test' is ginned up, he performs some spurious activity, and explains how it proves the airplane is (fill in the blank).