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19 Mar 2024, 07:13 [ UTC - 5; DST ]


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 24 Apr 2017, 16:38 
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I'm watching this with interest. I've a friend that I just put 20 hours with in his new 210 that has a deposit down on one of these Raptors. He's kinda like, "If it works out fine, if not; I've got an airplane to run around in now.


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 07:43 
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The powerplant sounds great but honestly it scares the heck out of me and seems like it should be in it's own completely separate engineering project. They're taking a well engineered system then changing the application, replacing turbos, replacing and remapping ECU, etc. Having done this for automotive applications it is not something that increases reliability of the power plant compared to what the factory engineers designed and tested for.


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 10:00 
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Username Protected wrote:
The powerplant sounds great but honestly it scares the heck out of me and seems like it should be in it's own completely separate engineering project. They're taking a well engineered system then changing the application, replacing turbos, replacing and remapping ECU, etc. Having done this for automotive applications it is not something that increases reliability of the power plant compared to what the factory engineers designed and tested for.

Aside from the fact that a large amount of serious engineering effort goes into any modern automobile engine with several goals which aren't particularly aligned with a high altitude aircraft application, a very significant challenge is mitigating the huge stresses involved with driving the high polar moment (resistance to angular acceleration) load with a high power diesel engine. This is where Thelert failed and where this project is likely to come apart as well.

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-lance

It's easier to fool people than to convince them that they have been fooled.


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 10:15 
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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


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 10:24 
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Location: CMB7, Ottawa, Canada
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Why reinvent the wheel when there is a few approved aero diesel out there now.

Focus on the airframe and put a proven engine in it.


Username Protected wrote:
The powerplant sounds great but honestly it scares the heck out of me and seems like it should be in it's own completely separate engineering project. They're taking a well engineered system then changing the application, replacing turbos, replacing and remapping ECU, etc. Having done this for automotive applications it is not something that increases reliability of the power plant compared to what the factory engineers designed and tested for.

_________________
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Pistons engines are for tractors.

Marc Bourdon


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 10:35 
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Username Protected wrote:
Lance,

I'm referring to the fact that they haven't been Just Building a Prototype They've been machining the forms to create the plugs on which the prototype and presumably all subsequent production models will be molded off of.

This isn't just some "carve a shape out of foam, slap on some fiberglass and call it an airplane" sorta project.


As to the math being way off? Gotta admit that I'm pretty skeptical as well as to whether or not he'll ever get those #'s.

But I am cautiously optimistic that he will indeed bring a product to market that maybe, just maybe might satisfy the requirements of many of us out here. Even if it is only a 200kt aircraft with 1,000 nm range, and can do that in pressurized comfort with a glass cockpit and for under $150K?

I know, I know, a lot of if's, but here's to hopin he pulls it off. :cheers: :cross:

In closing, I gotta tell some of you guys that it never ceases to amaze me how utterly pessimistic you can be. It's almost as if you are truly hopin this project falls on its face.

I for one don't understand that mentality.

Why would we not want this fella to succeed? Why would we not want a new kid on the block offering a high performance pressurized aircraft that can be had for the cost of a 40 year old A36?

But, what the heck do I know.


I think you're misreading the expectation of failure for the desire of same and at least for me that's completely wrong. I'm just pointing out from a somewhat scientific perspective that there's a big discrepancy between their claims and reality.

I would love to see these guys (or anyone else) succeed at their stated goals but I strongly suspect that their actual goal is to raise a lot of investment capital and live well while spending some of it attempting to build a flyable prototype that would increase the amount of cash flowing in.

The main source of MY pessimism is the combination of insufficient and/or obviously incorrect answers to obvious questions about the concept. If there was only one issue of this sort there's some chance that one issue could be resolved with the application of bleeding edge technology but history clearly indicates that almost any project that requires significant advancement along several fronts without an almost unlimited supply of money and talent is doomed from the start.

A good comparison is Vern Raburn's original Eclipse project which promised a light twinjet that would outperform existing aircraft at one third the price. This project (which had a considerably larger pool of money to spend) required several big advancements, among them the use of friction stir welding for economical and automated construction along with significant weight savings, a major development of a low cost but highly capable integrated avionics suite, a new engine with significantly better performance than existing designs coupled with much lower cost, and the development of an entirely new market for this type of airplane.

Of those lofty goals the welding concept was made to work albeit with much less cost savings than anticipated and couldn't come close to meeting the weight reduction goals, the original avionics development effort failed completely, the engine turned out to have way to little thrust (partially due to the higher aircraft weight than the initial design), and the market never materialized and even then it couldn't be produced at the expected cost.

And as someone already pointed out it's not just the engineers (or more likely marketing folks making engineering claims) who are bad at math. A projected price point of $150-200k for something as capable as they say this airplane will be is ludicrous. If they could really come close to the projected performance they would sell as many as they could build for three to four times that price which again leads me to suspect that the primary goal of this project is to raise money, not sell airplanes.

The bottom line for me is that if this project is as unrealistic as it seems it will actually result in less advancement in aircraft technology than would occur without it because when a more plausible project comes around the pool of venture capital will be smaller due to the memory of failures like I expect this one to become. And I'd be happy to be proven wrong but I'm not gonna put any of my money into this one.

_________________
-lance

It's easier to fool people than to convince them that they have been fooled.


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 11:57 
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Username Protected wrote:
Aside from the fact that a large amount of serious engineering effort goes into any modern automobile engine with several goals which aren't particularly aligned with a high altitude aircraft application, a very significant challenge is mitigating the huge stresses involved with driving the high polar moment (resistance to angular acceleration) load with a high power diesel engine. This is where Thelert failed and where this project is likely to come apart as well.


Can you explain? I am not an engineer. From what I read, the problems for the initial Thelert engines were TV related in the clutch. Hence the clutch and gear box replacement intervals. Over time, they have gradually improved both the clutch and the gear box.

Tim


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 12:29 
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Location: Lynnwood, WA (KPAE)
Aircraft: 1993 Bonanza A36TN
The history of auto engine conversions shows that getting them to certification level of reliability requires substituting so many custom parts that the cost savings evaporate. Thielert, Porsche, Toyota, Honda, Orenda -- Firms with far more serious engineering chops have tried and failed to do what these guys plan. I wish them luck but I'm not optimistic.


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 12:42 
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Aircraft: 1965 Bonanza S35
Username Protected wrote:

I think you're misreading the expectation of failure for the desire of same and at least for me that's completely wrong. I'm just pointing out from a somewhat scientific perspective that there's a big discrepancy between their claims and reality.

I would love to see these guys (or anyone else) succeed at their stated goals but I strongly suspect that their actual goal is to raise a lot of investment capital and live well while spending some of it attempting to build a flyable prototype that would increase the amount of cash flowing in.

The main source of MY pessimism is the combination of insufficient and/or obviously incorrect answers to obvious questions about the concept. If there was only one issue of this sort there's some chance that one issue could be resolved with the application of bleeding edge technology but history clearly indicates that almost any project that requires significant advancement along several fronts without an almost unlimited supply of money and talent is doomed from the start.

A good comparison is Vern Raburn's original Eclipse project which promised a light twinjet that would outperform existing aircraft at one third the price. This project (which had a considerably larger pool of money to spend) required several big advancements, among them the use of friction stir welding for economical and automated construction along with significant weight savings, a major development of a low cost but highly capable integrated avionics suite, a new engine with significantly better performance than existing designs coupled with much lower cost, and the development of an entirely new market for this type of airplane.

Of those lofty goals the welding concept was made to work albeit with much less cost savings than anticipated and couldn't come close to meeting the weight reduction goals, the original avionics development effort failed completely, the engine turned out to have way to little thrust (partially due to the higher aircraft weight than the initial design), and the market never materialized and even then it couldn't be produced at the expected cost.

And as someone already pointed out it's not just the engineers (or more likely marketing folks making engineering claims) who are bad at math. A projected price point of $150-200k for something as capable as they say this airplane will be is ludicrous. If they could really come close to the projected performance they would sell as many as they could build for three to four times that price which again leads me to suspect that the primary goal of this project is to raise money, not sell airplanes.

The bottom line for me is that if this project is as unrealistic as it seems it will actually result in less advancement in aircraft technology than would occur without it because when a more plausible project comes around the pool of venture capital will be smaller due to the memory of failures like I expect this one to become. And I'd be happy to be proven wrong but I'm not gonna put any of my money into this one.



Lance,

Thanks for your response, as well as your position on the matter regarding expectations vs hopes.

As to your comment suggesting that these guys are simply trying to raise cash and roll deep while they're trying to develop a flyable prototype, well I do hope you're wrong and can only base my cautious optimism off of what he's published on his site regarding the 800 refundable $2000 deposits being held in escrow @ Escrow.com

http://raptor-aircraft.com/ordering.html

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"TRUTH is AUTHORITY..... Authority is not Truth"


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 12:59 
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It took forever to get 100k refund on the diamond jet.


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 13:13 
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Username Protected wrote:
a very significant challenge is mitigating the huge stresses involved with driving the high polar moment (resistance to angular acceleration) load with a high power diesel engine.


Can you explain? I am not an engineer.

Lance is saying that the usual problem of per-combustion-event energy transfers into and back out of the propeller (described by the articles linked below) is much worse with a diesel engine.

http://www.epi-eng.com/piston_engine_technology/torsional_excitation_from_piston_engines.htm

http://www.epi-eng.com/propeller_technology/propeller_vibration_issues.htm

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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 13:32 
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They should just bolt this engine to the plane....

https://eps.aero/

They have been making steady progress on this engine, with a goal of
certification in 2017. (Not bad since they predicted 2016 certification in 2013, so slipping, but not by much) The company looks like the real deal.

Its my understanding that they have received all of the investment they need to reach certification.

I actually think that one of these engines bolted to a lanciair evolution would be ideal.
It would have more than enough range to go anywhere in the world.


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 13:36 
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Username Protected wrote:
It took forever to get 100k refund on the diamond jet.


Not held in escrow.
Key difference.

Still not going to put money down though...

Tim


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 13:38 
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Username Protected wrote:
The history of auto engine conversions shows that getting them to certification level of reliability requires substituting so many custom parts that the cost savings evaporate. Thielert, Porsche, Toyota, Honda, Orenda -- Firms with far more serious engineering chops have tried and failed to do what these guys plan. I wish them luck but I'm not optimistic.


Diamond AE-300 engines have done well, and they share a lot of parts with the production MB engines.

Tim


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 Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die
PostPosted: 25 Apr 2017, 13:45 
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Username Protected wrote:
Lance is saying that the usual problem of per-combustion-event energy transfers into and back out of the propeller (described by the articles linked below) is much worse with a diesel engine.

http://www.epi-eng.com/piston_engine_technology/torsional_excitation_from_piston_engines.htm

http://www.epi-eng.com/propeller_technology/propeller_vibration_issues.htm


If Lance had just stated torsional vibration, I would have followed :D
The PSRU on the CMI CD-155 (Thielert) has a clutch pulley to reduce TV; Diamond on the AE-300 went with a heavier TV fly wheel disk (I forget the actual name).

Tim


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