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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 21:55 
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Username Protected wrote:
Didn't have time to read through the EPI content yet, but wouldn't the use of a reduction belt drive minimize any vibration related to the propeller?


Minimize no. It just changes the frequency; which can be beneficial depending on what you are doing.
Now the belt with idle tensioners on both sides of the power pulley can be used to reduce/eliminate TV. How to actually accomplish this is way over my head. :)

Tim

Damping the torsional impulses is usually accomplished with a combination of a high moment flywheel, crankshaft dampers, and careful attention to harmonics. A flexible belt drive could absorb some of the energy but by doing so it would have to convert it to heat which would likely be a problem for belt life and maybe efficiency.
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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 22:34 
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>Where is the steady progress? Their "Latest Update" was 3 years ago

One of the company investors hangs out at the Aerostar forum (paid forum)
and comments regularly on progress.

They have all the funds they need and have a bunch of time on a conforming engine.
They are in the process of setting up a pilot production run of 100 or so,
they also have interest from the Airforce for use as an efficent drone engine.

They should present at OshKosh again this year (as they did in 2016)

Paul


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 27 Apr 2017, 02:00 
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This from their site...


From that list the avionics total is $37,500 a bit less than half of my guess (I was thinking of certified avionics) but it's also a pretty minimal panel for a 200+ kt high altitude cruiser. No stormscope, backup instruments etc.

I'm also wondering how a "kit" consisting of prefab fuselage, wings, and tail plus a bunch of systems to install can meet the 51% rule but Epic managed about the same thing if the builder spent a month at the factor being "assisted".


This is from the FAQ so it looks like they're taking the Epic route:

3. How much time do I need contribute to the construction of the aircraft?
The minimum requirement in order to still satisfy the 51% rule for experimental aircraft will be 2 weeks at a construction facility where you will be supervised in closing out various components of the airframe so you have a decent understanding of how your Raptor is constructed. For most people this will be a very fun and exciting adventure. Once the airframe is complete we can transfer it to a build completion center for the engine, avioincs, interior and paint or you can have it delivered and complete these items yourself. We are going to recommend a completion center as they will have a production line approach to completion and have your aircraft flying faster and for less cost than you can do it yourself. Again, the $130K price is the finished and flying price that we are presently projecting.


Personally I think they're dreaming, but hey I applaud them for the dream because it looks like they're actually really working on it from the medium page. Assuming it flies well, if they pull 90% off it'll be amazing at even double the price.

I wonder if it would be able to handle a RR M250 (or other turboprop engine) and fly faster for more fuel burn? They don't have a VNE per se, but merely a theoretical max speed if they can provide the power.

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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 27 Apr 2017, 15:19 
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Username Protected wrote:

I wonder if it would be able to handle a RR M250 (or other turboprop engine) and fly faster for more fuel burn? They don't have a VNE per se, but merely a theoretical max speed if they can provide the power.


It was originally planned to be a turboprop before they switched to diesel.

https://www.indiegogo.com/projects/rapt ... aircraft#/


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 27 Apr 2017, 15:27 
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yes auto engines are a challenge. The reason the little corvair engines work well is that they were originally designed to be a helicopter engine. Makes them a crappy car engine but a decent airplane powerplant. Even then though, not every corvair crank can take the prop stresses, has to be a nitrided crank


Jeff,

Do you have any actual evidence of the Corvair engine being originally designed as a helicopter engine? I found several rumors to this effect on the interweb, but no actual documentation.

Also, why do you say they were a crappy car engine? I had a couple of them, and thought they were great--except, of course, for a tendency to leak oil at pushrod tube seals, valve cover gaskets, etc.. One neat feature was that if you put the spring-loaded fan belt idler on, you could slip the fan belt off for a few minutes to gain 25-30 HP for a drag race. Surprised a lot of guys with bigger/faster iron with that little trick!


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 27 Apr 2017, 15:38 
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Location: Peachtree City GA / Stoke-On-Trent UK
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Username Protected wrote:
yes auto engines are a challenge. The reason the little corvair engines work well is that they were originally designed to be a helicopter engine. Makes them a crappy car engine but a decent airplane powerplant. Even then though, not every corvair crank can take the prop stresses, has to be a nitrided crank


Jeff,

Do you have any actual evidence of the Corvair engine being originally designed as a helicopter engine? I found several rumors to this effect on the interweb, but no actual documentation.

Also, why do you say they were a crappy car engine? I had a couple of them, and thought they were great--except, of course, for a tendency to leak oil at pushrod tube seals, valve cover gaskets, etc.. One neat feature was that if you put the spring-loaded fan belt idler on, you could slip the fan belt off for a few minutes to gain 25-30 HP for a drag race. Surprised a lot of guys with bigger/faster iron with that little trick!

when I was an entry-level engineer at GM there were several old timers in our lab who worked on the corvair design back at its beginning. They said that the engine was all but done and had taken an enormous amount of R&D effort, and when the helicopter project was cancelled they basically designed a car to go around the engine to try and justify the expense.

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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 28 Apr 2017, 09:28 
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TL;DR: Never a "helicopter" engine ... according to a friend that worked in Chevy (R&D) at that time. (1955-1970).

Long story as told to me last night at dinner:

Chevy R&D was (really) a race car shop ... and the skunk works for Ed Cole, Zora Arkus-Duntov and Frank Winchell. The facility was truly off-limits to the rest of Chevy/GM engineers and execs. R&D had their own budget, model shop, draftsmen, engineers, dynos, etc. Internally, it was referred to as the Toy Store.

As the official GM position was "no racing," they would concoct explanations to obscure their actual work. But the boxer was too different to explain using the common "heavy duty" or "towing package" explanations. This was the same time-frame as the media was hyping personal helicopters, so "helicopter engine" was plausible disinformation for the development of the boxer.

He mentioned one engineer building a 1-off seaplane that had the engine buried in the fuselage nose, using a jack-shaft & belt to drive a pylon mounted prop.

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Last edited on 28 Apr 2017, 15:52, edited 3 times in total.

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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 28 Apr 2017, 11:16 
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well, the pictures my old coworkers showed me of the helicopter gearbox on their test stand, would make it seem like they really went overboard with such a hoax. Or, maybe they were telling me the truth. I tend to believe them because the guys i worked with didn't have enough of a sense of humor to do what you describe


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 28 Apr 2017, 16:33 
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Perhaps a race car transmission? The first prototype Chaparral transmissions were 1-speed manuals - not a typo.

Curtis LeMay and Zora were apparently buddies ... and it was not unusual for Zora to commute between Detroit and Omaha by USAF T-33. And C119's built at Willow Run may have hauled a few Corvettes to:from Omaha. Apparently they needed "ballast" for CG matters - safety first! :liar:

Interesting to hear him compare and contrast the team and testing operations of Penske, Yunick, Hall, Donohue, Yenko, Fitch, etc. Also ... their radio-telemetry van ... the computer models of the cars and tracks.

I suggested he write a book, but he declined, saying the real story is no where near as compelling as the accumulated embellishments of history.

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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 28 Apr 2017, 19:35 
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This is waaay off topic but to pick up on the Air Force transportation. How about renting a U-Haul van that drives up into a C-130 to get delivered across the country. Fast forward to returning it with that very low mileage and you have the management scratching their heads.


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 29 Apr 2017, 21:05 
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Location: Franklin, TN 615-739-9091 chip@jetacq.com
Username Protected wrote:
Perhaps a race car transmission? The first prototype Chaparral transmissions were 1-speed manuals - not a typo.

Curtis LeMay and Zora were apparently buddies ... and it was not unusual for Zora to commute between Detroit and Omaha by USAF T-33. And C119's built at Willow Run may have hauled a few Corvettes to:from Omaha. Apparently they needed "ballast" for CG matters - safety first! :liar:

Interesting to hear him compare and contrast the team and testing operations of Penske, Yunick, Hall, Donohue, Yenko, Fitch, etc. Also ... their radio-telemetry van ... the computer models of the cars and tracks.

I suggested he write a book, but he declined, saying the real story is no where near as compelling as the accumulated embellishments of history.


Brings back memories, I grew up in Midland, Texas and we use to ride our dirtbikes through the field behind Jim Hall's test track, we'd sneak up the berm and watch them run the car.

Many years later I got to know Franz Weis, they built a new dyno at Hall Racing with the ability to test engines up to 15,000 rpm (if memory serves me) to be able to dyno the new Mercedes motors they were running.

Franz called me one day and said "chip, come down... we blow up a motor today"

He was right, they cranked it up until it failed, we were all waiting for a dramatic explosion... but on the other side of the bullet proof glass it was just a loud pop and the glass was instantly clouded by oil and smoke.

I have a lot of fond memories of Pennzoil #2, #4 and #8... saw them all when they were still white.

P.S. I didn't know about the single speed manual, I did know that they pretty much pioneered automatic transmissions in racing.

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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 20 Aug 2017, 12:28 
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I just ran across this thread and got caught up. Interesting read. I noted that the "naysaying" has dropped off a bit, but the good news is that the Raptor folks are still building; it's hard to imagine it being a "scam" as so often stated in this thread with so much video evidence to validate their efforts. After reading the thread to this point, there are few points that should be made:

- As to needing more support and credibility: I noted that there are now at least 1070 escrow deposits. That show's a lot of support for an airplane kit in my book, notably at $2,000 each.
- Per the terms of the escrow, the escrow doesn't transfer to Raptor Aircraft until after the prototype performance has been validated and final costs are presented. At that point, you have the right to withdraw your escrow, or if you choose, proceed. Even so, the Peter Muller has said that an owner will be able to withdraw their deposit up until their kit is ready for production.
- A very critical point: The Raptor is an experimental airplane, not certified. If the prototype comes to fruition, it will be sold as a kit - not a fly-away airplane. Therefore the costs won't be in the same ballpark as a certified airplane; expectations should not be the same either.
- It may not make the performance or cost estimates. But that's the whole point of "experimenting".
- The 51% rule is based on tasks, not cost or time. For example, it might take Van's Aircraft 4 hours to build a wing spar and it's an expensive part of their kit. But, it's one task. I install the landing lights - that's one task. So, it is conceivable that their kit will comply with the 51% rule without much issue; it just requires good documentation.
- There are way too many variables on an aircraft for an armchair quarterback to make claims of how the airframe will peform simply by discssuing possible drag and power - unknowns by themselves. If the engine performs and the airframe is slick, which it appears to be, then it be a screamer.

It doesn't take a lot of imagination to tear down and poke holes. It's another thing entirely to imagine, design, and construct. I applaud these folks for continuing on in spite of the criticism of how what they're doing can't be done. They may not make it, but at least they're out their trying. As an engineer, I'm impressed with their concept, let alone what they've accomplished to date. I'm very happy to keep watching them work away at this and I'm pulling for them. They may miss the mark of their expectations, but then again, they may prove all of the "it can't be done!" folks wrong (the same folks, mind you, who will line up and buy it if turns out to be a good airplane). Good for them and God bless 'em.

If they can get kits into production at a reasonable cost and performance, I will be happy to buy one. If they don't, then I'll consider something else, like a Velocity Twin. Or maybe I'll just actually finish my RV-12 and fly it...it takes a lot of time to build an airplane - even a simple one.

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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 20 Aug 2017, 15:44 
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Ron,

I largely agree with you although this aircraft is not one that I would want to own or fly. I think they are taking a step too far in trying to put out an experimental aircraft with an experimental engine and pressurized and with parachute to boot. But I certainly wish them luck...

As Teddy R pointed out:

It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat.

Blue skies,
Tom


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 20 Aug 2017, 15:49 
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Ron,

Well stated. The openness of their project, by the release of twice weekly video's continues to amaze me.

I just drool over the thought of 230 KTAS cruise, at 25k, pressurized, and with a BRS chute as your second engine :-)

Not to mention a modern glass panel with a digital autopilot and I think FIKI (not sure).

Of course, there is so much more to be done, but I suspect this project is less than a year from a flying prototype.

I am "|-- --|" this close to putting down a deposit, as it appears to be almost risk free (caveat emptor).

Have any BTers put down a deposit yet?

Anyone know where they are building this?

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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 20 Aug 2017, 16:49 
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Username Protected wrote:
- Per the terms of the escrow, the escrow doesn't transfer to Raptor Aircraft until after the prototype performance has been validated and final costs are presented. At that point, you have the right to withdraw your escrow, or if you choose, proceed.


Mr. Muller did offer deposit-holders an option to lock in a below market ready-to-fly price and a small piece of the company for some additional non-refundable cash deposits a while ago. It seemed like a good opportunity for some depositors to further fund the development. In any case, based on the video evidence posted each week it seems to still be funded enough to continue development of the prototype. My guess is that once the prototype is flying (or any one of the many remaining milestone steps are completed) there will be greater interest in the project financially. Or, there will be lots of skeptics saying "told you so."


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