10/23 Raptor Video

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rv6ejguy

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When you have no materials knowledge/ experience and are too lazy to even look up physical properties of a material you plan to use online- failure is often the result. Could have saved himself 2-4 weeks delay with 5 minutes of research. There are really good reasons why you don't see Delrin used in gearboxes...

The title in the video also applies to the cabin which is another big issue to solve.
 

Marc Zeitlin

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Mark Z said:
The hobbs is getting closer to 40 hours. Isn’t that the goal?
End goal isn't clear. That may be short term goal.
So there's been a bunch of speculation here regarding the Airworthiness Certificate, Operating Limitations, Area Restrictions, and other issues surrounding possible flights to California and other testing.

Not being one for speculation, I spent the $10 to get the aircraft records from the FAA for N352TD (Raptor Prototype), since I had only seen the first AC / OL's, not the second set. They're public, if you pony up the dough, which I did.

N352TD is certificated as Experimental R&D, NOT Experimental Amateur Built. Therefore, there is no hour limit within which the plane is restricted in what it is allowed to do. Although the CURRENT Airworthiness Certificated, signed on 08/24/2020, does not indicate an expiration date, it DOES say that it's effective under the conditions prescribed in 14 CFR Part 21.181 and 21.217. 21.181 clearly states that the AC for an Experimental R&D aircraft is good for one year from the date of issue, meaning that this AC will need renewal on 08/23/2021. The restrictions on the plane exist for the full one year period.

The Operating Limitations for E-R&D do NOT specify a test area, subsequently allowing unrestricted flight, as with E-AB aircraft. They specify a test area which is in force for the full one year time limit of the AC, and there shall be no flights out of the test area during that time period. In the case of N352TD, the test area is defined as a 25 mile radius around Valdosta Airport (KVLD) for the first 10 hours of flight (which it may have achieved, by this point, but IIRC he's never been more than 5 miles or so away from the airport) and as a 50 mile radius around KVLD after the first 10 hours, however many hours that might be within the one year period.

The airplane may fly as few or as many hours as desired within the one year period ending on 08/23/2021, but it is not legally allowed to fly outside of the 50 mile radius from KVLD. It is possible for PM to obtain a ferry permit from the FAA, with signoff from an A&P (and I'd be very interested to know which A&P signed off his FIRST Condition Inspection just prior to the AC issuance, or whom might be willing to sign off a ferry flight) indicating that the aircraft is in a condition for safe operation on the ferry flight to wherever it may be going. And then a new AC / OL would have to be issued with a new test area within the E-R&D scope.

So, some actual facts.
 

Jay Kempf

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Thank you for providing the materials info. It's always surprising to me how few people know of Teflon's infinite creep characteristic. Even plumbers think that "Teflon tape" is for sealing pipe threads - it cannot seal anything at the remarkable pressures developed between tapered threads, It's an assembly lubricant so that greater torque can be applied to attain the thread deformations need to seal..
Just to be complete on the subject cause I used to have to go do presentations at WL Gore and assoc., pipe sealing plumbers white tape is mostly GoreTex or the generic "expanded" PTFE. When PTFE, Teflon, is expanded properly it becomes a high tensile matrix that does not have the original characteristics of the base PTFE, Teflon. So yes it is a thread sealant in that regard. Been there at the Gore factory and got the T shirt. Remarkable stuff. I am an avid snow skier. Goretex is amazing stuff.
 

BBerson

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So, some actual facts.
Right. All this was discussed in the past here and yet PM continues to talk about the "40 hours".
Is it possible this owner or most owners don't read or retain memory of operating limitations?
Certainly the video followers are not aware of E-R&D limitations but they have heard of the "40 hours" experimental thing.
I wouldn't be surprised if it got trucked to Oshkosh in July on the way westward.
 

Marc Zeitlin

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Right. All this was discussed in the past here and yet PM continues to talk about the "40 hours".
I haven't been paying close attention - is PM really discussing some 40 hour limit on flight testing? And flying the plane outside of the 50 mile radius from KVLD?
Is it possible this owner or most owners don't read or retain memory of operating limitations?...
All I can tell you is that a substantial portion of both the original builders (the folks that actually APPLIED FOR and got the AC/OL's in the first place, for Cthulhu's sake) and any subsequent owners just look at me with a blank stare when I ask "can I see the Operating Limitations, please?" and 1/2 the time, hand me the POH. "Someday, son, all this will be yours." "What, the curtains?"

Sigh.

Having written a couple of Program letters for E-AB aircraft, and five Program Letters for E-R&D aircraft, including OPA E-R&D aircraft, I never cease to be amazed by my own amazement at the lack of comprehension of the majority of folks as to what they are and are not allowed to do with their airplanes...
 

Wanttaja

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All I can tell you is that a substantial portion of both the original builders (the folks that actually APPLIED FOR and got the AC/OL's in the first place, for Cthulhu's sake) and any subsequent owners just look at me with a blank stare when I ask "can I see the Operating Limitations, please?" and 1/2 the time, hand me the POH.
I'm the fourth owner of my Fly Baby, and I didn't get Operating Limitations with the purchase. Previous owner was a friend, a well-organized type, so I suspect he's not the one who lost them.

Got a copy from the FAA. "Oh my gawd...I'm not supposed to perform aerobatics!!!!" :)

The original builder actually crashed the airplane (with no mention in the logs...) and I think it was a rush sale to someone after he patched it up (literally... one ugly repair, there).

Ron Wanttaja
 

BBerson

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I haven't been paying close attention - is PM really discussing some 40 hour limit on flight testing? And flying the plane outside of the 50 mile radius from KVLD?
I think he mentioned "the 40 hours before moving" to the "west coast". No flights more than 5 miles and within gliding range so far.
I suppose the 40 hours could simply be a prudent self-imposed test schedule, considering all the experimental systems.
I remember the Raptor rush to get it to "Oshkosh" a few years ago. Things happen.

Burt worked long hours to get SkiGull ready for Oshkosh (I guess in 2016?). Still no show so far. Things happen.
 

lelievre12

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The Delrin part actually failed in tensile yield before it melted. I missed this 'weakness' when I was predicting it would fail due to melting. Of course its all there in the specs:

Acetal Yield.JPG

Yield strength at room temperate is only 9000psi. At 290F it will be far less. Steel by way of comparison is around 40,000psi.

And Young's Modulus for (tensile modulus) for Acetal is 2.8 whereas steel is ~200.

Of course I should have known that Delrin is practically useless in tensile engineering applications.

Once pressurized with hot oil and under tension, inevitably the part expanded and leaked oil. Perhaps mercifully as if it had lasted long enough to fly then it would have melted and perhaps caught fire.
 
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