Raptor NG Discussion

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bmcj

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His engine/drivetrain choice seems to be one of his biggest enemies. I’m not an engine person, but I have learned a lot from reading the powertrain posts and critiques written here by those who know and understand powertrains.
 

Aesquire

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So...if he had done it with one of Continental's diesel engines instead of homebuilding his own, would that have made the project viable?
IMHO there were a couple of problems with the Raptor.

The First was developing a New Airframe and a New Engine at the same time. It has been done, but adds a lot of time and cost, and greatly reduces the chances of success. So... Yes, a commercially available engine that he could just "ignore" besides proper maintenance and operation would have helped a lot. It was, after all, an engine ( PSRU ) related failure that ended up putting him in a field.

Second is issues with overweight construction, and every fix seemed to just add more weight. It's possible that with a reliable engine he could have properly tested the aerodynamics of the design, and the second prototype might have fixed the weight issues. Maybe.

Third is arguable, and I'm not going to comment on attitude or design philosophy. The above is all MY OPINION, and others may disagree.
 

Geraldc

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Pure speculation.
Someone buys existing Raptor and intellectual property then makes one with conventional powerplant no pressurisation and tidies up other probems.
There was a lot of interest and people willing to buy.
Raptor NG is Peter's own project moving forward and can not be same as old Raptor.
 

BJC

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wsimpso1

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Engine was very heavy for 300 hp, because turbos were sized way off, intercooling was way undersized, psru concept was all wet, cooling was garbage. The amount of cooling air required was much more than was planned for. Dog's breakfast...

Then the airframe was simultaneously way heavy, and in places, soft too. Crappy concepts and execution.

Then the performance goals bore no resemblance to reality - just impossible.

Billski
 

henryk

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Engine was very heavy for 300 hp,

=iff, >90 % efficiency...?

BTW=2-place VOLKSWAGEN XL1 "consume" <0.9 l diesel /100 km ,<160 km/h)
 
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cheapracer

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I know there's already been a lot of discussion around the developments of Raptor aircraft lately, but after reading the thread, a few questions remain unanswered:
1) What did we learn from the prototype?
a. Did the aircraft, as Peter Moller designed it, meet specs?
b. How badly, and in what aspects, did it miss?
c. I've heard people mention that it fell well short of what was promised, but can anyone link the source on those numbers?
d. Also, was the airframe ultimately similar to the velocity, and did it perform similarly? If not, why not?
1) That you can't jump into a 100 year old arena full of hundreds of combatants, who have tested every weapon you can possible think of, and think you have invented a new weapon when you haven't even stood in the arena yet.

a. No, not even close.
b. "No, not even close" explains how badly, weight is it's major failing, as in literally double the weight is could have been. "DOUBLE" is not an exaggeration.
c. Velocity, it's closest class design philosophy, are around 1800 to 2000lbs, Raptor was 3600lbs, again I mention the word "double".
d. Sorry if I'm boring you with the word, but at "double" the weight, you have a snowball's chance of rolling uphill of matching a similar craft that's half the weight.




2) Is the original goal of Raptor achievable?
a. Personally, I was really impressed he made a working prototype in a relatively short period of time, I don't understand why he's throwing all that away.
b. The original goal of Raptor, as far as I understood, was to stick a Diesel engine in a Velocity and get a pretty nice and cheap cross-country machine. What changed that he doesn't want to pursue that anymore?
2) Yes it is, based on a diesel Velocity, you might be say 300lbs over with the experienced Velocity team doing the development build, but you would get close.

a. I have to disagree with you, it was a very long build, amplified by many, many mistakes constantly needing to be rectified. throwing away a prototype is common, and heartbreaking sometimes, I have done it as recently as last week :)
b. You would have to ask him, but it would have been wise to develop the diesel first, then the new airframe. Had he been successful with the diesel development, he would have had a profitable market and use those funds and staff to develop the airframe. eg; He bit off more than he could chew.





3) Why is Peter Moller suddenly pivoting more into the realm of science fiction?
While this is obviously a setback, he's still not in a bad position to rebuild the prototype, possibly with improvements, and continue on the original raptor concept, which had a lot of interest (deposits).
Did something change that caused him to think he needed to do something so much more radical?
I guess this ties in with question #2, but I don't see why he suddenly needs to change direction and pursue something so different, especially after he made so much progress towards the original goal.
Apologies if the answers to these questions are obvious to those with more experience in aviation. I would really appreciate any insights!
3) An inexperienced IT guy trying to set the World on fire with the complete package, was always outside of reality. I'm not a physiologist, but he has demonstrated that his belief in himself appears to allow himself to confidently stray into grey areas of reality and fantasy without having a decisive border between the 2, and denying anybody who he feels is not 100% on his side.

I can't answer the rest because I don't know what's in his mind, but i think he demonstrates a selfish lack of empathy for all those who supported him over the years by just saying "Sod it", and moving on to the next thing that interests him.
 

AdrianS

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1) That you can't jump into a 100 year old arena full of hundreds of combatants, who have tested every weapon you can possible think of, and think you have invented a new weapon when you haven't even stood in the arena yet.

a. No, not even close.
b. "No, not even close" explains how badly, weight is it's major failing, as in literally double the weight is could have been. "DOUBLE" is not an exaggeration.
c. Velocity, it's closest class design philosophy, are around 1800 to 2000lbs, Raptor was 3600lbs, again I mention the word "double".
d. Sorry if I'm boring you with the word, but at "double" the weight, you have a snowball's chance of rolling uphill of matching a similar craft that's half the weight.






2) Yes it is, based on a diesel Velocity, you might be say 300lbs over with the experienced Velocity team doing the development build, but you would get close.

a. I have to disagree with you, it was a very long build, amplified by many, many mistakes constantly needing to be rectified. throwing away a prototype is common, and heartbreaking sometimes, I have done it as recently as last week :)
b. You would have to ask him, but it would have been wise to develop the diesel first, then the new airframe. Had he been successful with the diesel development, he would have had a profitable market and use those funds and staff to develop the airframe. eg; He bit off more than he could chew.







3) An inexperienced IT guy trying to set the World on fire with the complete package, was always outside of reality. I'm not a physiologist, but he has demonstrated that his belief in himself appears to allow himself to confidently stray into grey areas of reality and fantasy without having a decisive border between the 2, and denying anybody who he feels is not 100% on his side.

I can't answer the rest because I don't know what's in his mind, but i think he demonstrates a selfish lack of empathy for all those who supported him over the years by just saying "Sod it", and moving on to the next thing that interests him.
You left out the "I'm too smart to need advice" bit.

I don't know about airframes, so I'll leave that to someone else, but that driveline...

It should be possible to use an automotive diesel, but I'd be talking to people who know their stuff re mapping, cooling, turbo sizing, etc. He didn't.

The powerplant then requires extensive ground testing to sort out problems before trusting your life to it in the air. He didn't.

It should be possible (but difficult) to build a PSRU for that application, but it requires research into what's been done before, some expert analysis and design, and lots of proper ground testing.
He did none if those things.

I write software for a living, as PM apparently did. But he seemed to take the approach that you can just bodge it together and fix the bugs as you go along. That works for some types of software, but not safety critical stuff, or aeroplanes.

If I did that in my field, there's a genuine risk of damaging expensive equipment, injuring people, or worse.
That's why we design, analyse, and test. It's hardly rocket surgery.
 

rv6ejguy

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To clarify, I've watched most everything he's posted and written, but again I've no experience with engines or building aircraft, so the answers to the questions above are not clear to me. If he gave specs on the prototype other than climb-out speeds I missed that, and I'm not finding the answer from any search engine.
Peter would never have published a chart showing projected performance vs actual prototype performance as that would have driven home just how far apart these were. In fact, all the projected performance numbers vanished from his website, along with most of the other content a bit later, many months ago now. You can still find it archived online if you look. I did a YT video on Raptor a few months before its demise, covering some, but not all, of the issues with the project where I correctly predicted another redrive failure and the severe cooling issues it had which brought it to its sad ending. I also did some charts showing how much it fell short of his predictions and how it compared to a variety of existing designs.

I've already stated how NG will also be a failure from a technical standpoint, perhaps even more so the Raptor 1.
 

nschmandt

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@cheapracer thank you very much for that detailed breakdown! I really enjoyed reading your response, thank you, it's much more clear to me now why he failed and why he chose to give up rather than keep trying.
Thanks also to others for the responses! Really interesting to read everyone's thoughts.
 

Martin W

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@cheapracer thank you very much for that detailed breakdown! I really enjoyed reading your response, thank you, it's much more clear to me now why he failed and why he chose to give up rather than keep trying.
Thanks also to others for the responses! Really interesting to read everyone's thoughts.
.

He didn't choose to give up .... the Raptor itself gave up.

That should tell you plenty

..
 

Malish

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Engine was very heavy for 300 hp, because turbos were sized way off, intercooling was way undersized, psru concept was all wet, cooling was garbage. The amount of cooling air required was much more than was planned for. Dog's breakfast...

Then the airframe was simultaneously way heavy, and in places, soft too. Crappy concepts and execution.

Then the performance goals bore no resemblance to reality - just impossible.
Hybrid powerplant with electric ducted fans will need 450-500 hp engine and it's will weight probably twice more than engine, gearbox and prop on original Raptor aircraft... And what it's will do with CG location on Raptor NG(I'm not even talking about gross weight of aircraft)?
 

lelievre12

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I actually built a series DC hybrid system for a catamaran and unfortunately the numbers are not good. From the IC engine all the way to the prop are efficiency losses which are reductive. Using napkin numbers it goes something like this;

IC engine BSFC -->BLDC generator 85% --> 95% caps/rectifier --> 95% wiring --> 90% BLDC controller --> 85% BLDC fan motor.

When you do the math 0.85 x 0.95 x 0.95 x 0.90 x 0.85 = 58.6%. Or put another way 41% of your internal combustion engine power is lost before it gets to the prop. Or put yet another way, more than a third of your fuel load is wasted when compared to direct drive or even a PSRU.

And I haven't included any batteries yet. Round trip efficiency for charging and discharging batteries varies from ~60-85% depending on type. So the weight and losses from this have to be added to the numbers above if you add batteries to the drive.

We can argue each of the numbers but the principles remain. Reductive losses like this will never fly and in my own case made for a pretty crappy marine drive.
 
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Vigilant1

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We can argue each of the numbers but the principles remain. Reductive losses like this will never fly and in my own case made for a pretty crappy marine drive.
Thanks.
About the only way an approach like this makes any sense for a flying machine is if it provides some countervailing advantage that is very important and that can't be better achieved in other ways. In some cases (e.g. distributed propulsion, multicopters, etc) it might be worth doing, but efficiency will always be poor.
 

lelievre12

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Thanks.
About the only way an approach like this makes any sense for a flying machine is if it provides some countervailing advantage that is very important and that can't be better achieved in other ways. In some cases (e.g. distributed propulsion, multicopters, etc) it might be worth doing, but efficiency will always be poor.
My own view is that parallel hybrid systems may have aeronautical merit. This is where the IC engine drives the prop directly as now, however instead of a seperate alternator and starter, a BLDC is used to both start the engine and offer supplemental power during takeoff, max climb etc. Then on descent the BLDC can recapture some KWH. Perfect for circuit trainers etc. I think this is the route the Siemens and others are taking with their hybrid programs.

So parallel has a future, however series systems like Raptor NG looks to be, don't pencil at all.
 
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