Raptor Aircraft

Looks like someone has committed to test flying the aircraft. But surprise surprise, they won't do it until the ailerons are modified.
 
AA5Bman said:
I kind of checked into this process late in the game, but when he came out with an empty weight over 3,000 pounds I was like uh oh... and it seems to have only gotten worse from there.
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THIS
 
At least the builder is smart enough not to test fly it himself!
 
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OneCharlieTango said:
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As to admiration of his persistence in the face of... *ahem*... adversity, I think it's a sign of mental illness. Those who laud him with attaboys and berate the naysayers are enablers.
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Heck you just described type specifc clubs. LOL Jonestown stuff.

As to the moral imperative to warn others. Meh, now I understand why old people are so short tempered; they're tired to repeating themselves to people who won't listen. I subscribe to Canada Bill's philosophy these days: "its immoral to let a sucker keep his money". Caveat emptor pal. :D
 
If I gave up my career and decided to design airplanes, could I? Probably not, at least not without expert assistance. Here's the rub, though. I know there are no free lunches in aviation. You don't get something without giving something up. Vans are great aircraft on the same engines as lots of spam cans. Why? They gave up a back seat (except for the RV10, which doesn't do all the things its lower numerically named brethren do. Trade offs). My Mooney is loads faster than a Cherokee on the same engine. Why? Added complexity (constant speed prop and retractable gear) and a smaller frontal area, i.e. less room inside.

Were I going to try to design a kitplane these days I'd want something that no other aircraft had. Perhaps I've got a new way to put the pieces together so the build time is reduced. Maybe I've got a new material that's slick as snot and light to boot. Perhaps I've got a new engine that does something wonderful. Something new. I don't see anything that new about the Raptor. He's using carbon instead of silicon, but the weight savings in so doing are negligible at best. Yeah he's got an auto engine, but that's been done before as well, and they usually don't work as well as aircraft engines. I just don't see anything new. The superlative performance claims are clearly fantasy to anyone paying attention.

The Experimental that crashed awhile ago with it's designer in it looked pretty original at least. Whether it would have done what it's designer claimed I dunno, but it would have looked cool and different.
 
Sierra_Hotel said:
None. Do I have the mechanical aptitude to build one? Absolutely. The design experience to come up with a design? Yup. The ability to step back and realize I need a professional aircraft engineer's help in combining those 2 things? 100%. Just because I haven't done it is not for lack of wanting to or ability to, just like probably hundreds of other people on this board.
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Heck, a guy with nothing more than a Harvard degree in English designed and built two highly efficient airplanes, one of which traveled far and wide on the planet. He named them both Melmoth.
 
Kenny Phillips said:
Heck, a guy with nothing more than a Harvard degree in English designed and built two highly efficient airplanes, one of which traveled far and wide on the planet. He named them both Melmoth.
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and two brothers that didn’t get high school diplomas built the first successful aircraft.

and Al Mooney never went to college yet designed some fantastic birds. In addition to the company that carries his name, he worked as a designer for Alexander, Bellanca, Monocoupe, Culver, and Lockheed.
 
Kenny Phillips said:
Heck, a guy with nothing more than a Harvard degree in English designed and built two highly efficient airplanes, one of which traveled far and wide on the planet. He named them both Melmoth.
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skier said:
and two brothers that didn’t get high school diplomas built the first successful aircraft.
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..and Homer Hickam (October Sky) was building rockets in high school.. these weren't your paper Estes model rockets either.. but legit rockets.. he ended up with a career at NASA

but I think we've seen now that this Raptor guy is delusional
 
Not sure why they have such a problem with aileron control flex. Looks like they copied the setup the Velocity uses. They’re flexible cables and but they have enough stiffness to prevent flutter.
 
Velocity173 said:
Not sure why they have such a problem with aileron control flex. Looks like they copied the setup the Velocity uses. They’re flexible cables and but they have enough stiffness to prevent flutter.
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I think the difference is that this guy bought some cable and plastic tubing. The Velocity uses a teleflex type cable. Very rigid with not much play in it.
 
donjohnston said:
I think the difference is that this guy bought some cable and plastic tubing. The Velocity uses a teleflex type cable. Very rigid with not much play in it.
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Saw your gear failure vid on YT the other day. Sorry to see that. I’ve had a couple of episodes of wicked shimmy on landing where the friction wasn’t set high enough. Looking at upgrading to the beefier nose gear this year.
 
"What do you want to do, build an airplane or become a YouTube star?"

"Well, I don't know how to build airplanes, so..."

"Dude, you don't know how to do either one."
 
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Velocity173 said:
Not sure why they have such a problem with aileron control flex. Looks like they copied the setup the Velocity uses. They’re flexible cables and but they have enough stiffness to prevent flutter.
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The hard points in the system are not hard. They are flexible. So when you load the system, the hard points move and everything gets wonky. He's working on fix #2 now (Fix #1 was unsuccessful).
 
Velocity173 said:
Saw your gear failure vid on YT the other day. Sorry to see that. I’ve had a couple of episodes of wicked shimmy on landing where the friction wasn’t set high enough. Looking at upgrading to the beefier nose gear this year.
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Yeah, the newer nose strut is much beefier. I will also say that repairing the damage was a lot faster and a whole lot cheaper than when the nose gear on my 182RG collapsed.
 
DaleB said:
"What do you want to do, build an airplane or become a YouTube star?"

"Well, I don't know how to build airplanes, so..."

"Dude, you don't know how to do either one."
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Annoying video format aside, Elliot and Justin most certainly know what they're doing with respect to flight engineering and testing.
 
Tarheelpilot said:
Where are they in the assessment? Have they decided to fly?
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They have not decided to fly! Elliot and Justin, along with Mark Zeitlin, made a list of concerns that need to be addressed before any attempt to fly this thing. Apparently, the list has a number of items, including concerns with the aileron control system and the elevator system. If I had to guess, Peter is quite a ways away from any kind of flight........
https://www.homebuiltairplanes.com/forums/threads/raptor-composite-aircraft.24721/page-184
 
Seems some of the troubles are the questionable choices of materials being used. I think his first cable re-rig was done with non pre-stretched cable from the local box tractor supply.
 
Seems like this is just one of many aircraft designs that have come and gone (and I predict this one will too) over the years. Usually designed by overly ambitious, but necessarily qualified, entrepreneurs that have more skill in raising funds and selling dreams, than actual knowledge of physics or aeronautical engineering. They all come with lofty performance claims, higher, faster, more efficient, and cheaper, than the competition. However, I do believe without radical changes in the basic concepts and physics of aircraft design, we have seen the limits of what a light aircraft can do. I don't foresee us ever getting a true 4 seater that can do 250 kts on 4 gph, and all for the low low price of $50,000. Most real designs have come to realize you can't have it all, you have to compromise to get a realistic aircraft. It might be fast and efficient, but it won't be big...or cheap.
 
The latest "progress" video, posted yesterday evening, shows the most recent effort to correct the horribly designed and poorly executed aileron control system.

I haven't watched the entire eleven minute video. That's because my attention was interrupted in the first couple of minutes as the camera was aimed at a new access hole hacked into the 1" thick keel, the material of which appears to be about an inch thick layup of carbon fiber and foam. The constructor makes a comment about voids that had appeared in the keel layup, which had been "repaired" by injecting foam into the deficient areas.

Fashioning the newly provided access point involved cutting a large rectangular hole in the keel, which exposed a service channel and the previously abandoned aileron control cable route running parallel to the aircraft centerline. The cable route encounters pulleys which change the direction to vertical, running up the back of the rear bench seat.

Presumably, after that short vertical run and another pair of pulleys, the routing changes to a parallel orientation with the wings, where the cable routing would then terminate at a bellcrank somewhere in the wing and operate the ailerons, an area out of camera view.

This method had to be abandoned. The pulleys, critical elements of the directional flight control system, are wholly deficient. They have been attached to small triangular carbon fiber mounting brackets. These appear to be made from .095 CF material, and incredibly, they have been bonded directly to the .095 aircraft skin without any supplemental reinforcement on the surface or method to provide strength in all planes of movement.

Videos of these same brackets in other locations under movement loads generated by the control sidestick while the aircraft is being taxiied, show deflection which, magnified by the actual flight loads, would almost certainly cause catastrophic failure of the system and loss of aircraft control.

The contents of the keel service channel is a collection of everything one would hope not to see in an aircraft. It's hard to describe.

It is a collection of varied pieces and parts which move signals, commands, and information from one point to another. There are several pieces of ½" Schedule 40 PVC pipe, running parallel with and bonded to the keel, apparently intended to contain wiring and cabling that is instead run haphazardly through the keel. It is unmarked or otherwise unidentified.

Visible in the background are several braided stainless steel hoses with bulkhead fittings, apparently fuel lines that are penetrating the firewall. These hoses are again routed without consideration for proper support or good practices, which dictate wiring, cabling, and hoses should be run parallel and perpendicular to the aircraft structure.

Along with the wires and some twisted pair type cabling, there are six unsupported and unidentified plastic coated steel spiral wound cable sheaths located in the channel, remnants of a failed attempt to replace the initial and conventional method of aileron control with sheathed stainless steel cable. This proved to be a wholly deficient method, which was frankly a desperate and dangerous solution.

In the video, the aircraft constructor describes plans to now alter the cable and pulley system at its vertical change in direction exposed by the access hole. The method he describes envisions using non-aviation materials and methods along with larger pulleys to discard the original inadequate pulley mounting.

At this point in the video, I stopped watching. Beginning in videos posted about three weeks ago, the constructor has resorted to increasingly improper and possibly dangerous methods to repair deficiencies that have been revealed by taxi runs at low to moderate power and speed levels. Each run reveals further deficiencies and generates inadequate solutions.

It's becoming obvious the situation of the constructor has become one that will not have a good outcome. The possibility of an incident which might result in loss of control of the aircraft, even during taxi tests, may occur.

I hope he recognizes this possibility before it happens.
 
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I am not a pilot, so take my opinion with ever how many grains of salt it is worth. But I had to quit watching his videos. It became a little too painful for me. I am a little mechanically minded, so it has become apparent to me that his engineering seems to be almost like a shade tree mechanic working on cars. Or trying to design some specialty piece of farm equipment off the top of his head. I hope I'm wrong, but it seems that way to me.

My finite mind can only see two outcomes really. 1) This bird will never leave the ground (most likely outcome), or 2), a future test will result in mechanical failure and/or LOC that potentially results in human injury or worse (hope not).

It is a beautiful plane aesthetically. But aesthetics don't get someone from A to B safely. JMHO.
 
I watched the most recent video. What would the ramifications to structural integrity be by cutting the hole into the keel? Also the cut job was atrocious not care was given to tape of cut lines or anything to potentially reuse the piece, are they going to layup CF over the hole?

He's already shown some sort of integrity flaw with the passenger rear window cracking from just ground running and storing the aircraft.
 
This project kind of reminds me of the "Home Depot" airplane that a guy was building. Don't believe we found out how that ended up but I'm sure it never got very high off the ground (good thing).
 
I really admire his effort and vision. But I think he needs to stop and spend some time with Mike Patey and learn from him while he gets Scrappy and Draco 2.0 ready.
 
MacFlier said:
I really admire his effort and vision. But I think he needs to stop and spend some time with Mike Patey and learn from him while he gets Scrappy and Draco 2.0 ready.
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I was actually thinking earlier today while reading this thread that he needs to hire Mike Patey (seriously doubt he could afford him!).
 
3393RP said:
The latest "progress" video, posted yesterday evening, shows the most recent effort to correct the horribly designed and poorly executed aileron control system. ... It's becoming obvious the situation of the constructor has become one that will not have a good outcome. The possibility of an incident which might result in loss of control of the aircraft, even during taxi tests, may occur.

I hope he recognizes this possibility before it happens.
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I think he has too much perceived sunk cost (money and labor) in the thing to see the obvious.
 
MacFlier said:
I really admire his effort and vision. But I think he needs to stop and spend some time with Mike Patey and learn from him while he gets Scrappy and Draco 2.0 ready.
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Doesn't seem like he's interested in fixing other people's messes.
 
Kenny Phillips said:
I think he has too much perceived sunk cost (money and labor) in the thing to see the obvious.
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Yeah I couldn't imagine being in that situation, especially when it's also other peoples money.
 
Brad Smith said:
This project kind of reminds me of the "Home Depot" airplane that a guy was building. Don't believe we found out how that ended up but I'm sure it never got very high off the ground (good thing).
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What, the pink foam and plywood biplane? That actually flew, and didn't kill anyone. I don't know that this one will have the same happy outcome.

Oh, wait -- I remember what you're probably talking about. Plywood and electrical boxes, looked like it would weigh about 2 tons if it were ever finished?
 
DaleB said:
Oh, wait -- I remember what you're probably talking about. Plywood and electrical boxes, looked like it would weigh about 2 tons if it were ever finished?
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Yes, I'm referring the plywood and electrical box plane. And yes, the biplane version did fly!
 
Brad Smith said:
Yes, I'm referring the plywood and electrical box plane.
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The nice thing about that one is, assuming similar construction techniques throughout and assuming it ever actually got finished, there's no real risk that it would ever become airborne.
 
OkieAviator said:
He used push-rod controls though.
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This is something I've wondered, enough to risk posting in this thread instead of lurking in it. The Raptor website says this:

The Raptor uses push-rods for the rudder (bottom) and aileron (top). Using only push-rods will help to reduce any chance of flutter in the control surfaces. Obviously we will be doing a lot of flutter analysis and testing but why start with cables when you can use push-rods. It's better to go with the best of breed built into the design from the start.
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Obviously, at some point he decided to use cables and pulleys instead of push-rods in the first prototype. I haven't been following the progress until recently, so I don't know if he ever explained that change.

I also don't know that push-rods would help that much with the current problems. There seem to be two reasons for play in the aileron control system. The first is that the cables stretch, which push-rods would fix. But the second is that the pulleys are all mounted to carbon fiber skin that seems to have a lot of flex. Push-rods without stretch would just result in more of the forces being applied through the hinges to the airframe, since none of it would be absorbed by stretching cables.
 
All Y'all wishing him good luck and admiring him while he aint even flown this thing are part of the problem.

If everyone taunted him and finally convinced this fool to "Send it" and fly the thing...well then sounds like we would kill 2 birds with one stone. Literally. Cause this dude is about as smart as a dodo and Darwin is hard to avoid.

Cmon dude...Send it. Throttle up and pull back on the stick.
 
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