Raptor Aircraft

You know it's bad when it's dissed by ANN.
 
SoonerAviator said:
But again, ducting does little of anything for a pusher configuration when not in motion. There's no airflow to go through the ducting, lol. If you've ever dealt with older sports cars like the Corvettes, many of the high-hp models tend to overheat if they sit in traffic at idle. The radiators are small and steeply-angled (to fit in the narrow front end), they don't do well cooling a 427 in 95 degree heat. Once moving, they do just fine.

The Raptor certainly needs ducting/baffling, but it's not going to do a ton for idling on the ground or run-up.
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The air going through the prop has to come from somewhere, right?
 
Lindberg said:
The air going through the prop has to come from somewhere, right?
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Stand in the intake of a fan and then stand in the outflow. Which provides the best airflow to a direct location?
 
Lindberg said:
The air going through the prop has to come from somewhere, right?
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Sure, but when you're sitting still, it's not as if all the air going through the prop is being drawn across the intake scoop/radiator. Once you're moving a good clip you'd start seeing some effect. I would imagine if you could put a plate with some tufting in front of the prop (with no wind) you could find out fairly quickly the distance forward of the prop that air is being drawn across the fuselage/empennage. At idle speeds, the air being drawn into the propeller is slow moving and from a wide/broad area. Air volume in = Air volume out, but this isn't a ducted fan so the air velocity forward of the pusher-prop is likely of little consequence to aiding in drawing in cooling air.

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SoonerAviator said:
Sure, but when you're sitting still, it's not as if all the air going through the prop is being drawn across the intake scoop/radiator. Once you're moving a good clip you'd start seeing some effect. I would imagine if you could put a plate with some tufting in front of the prop (with no wind) you could find out fairly quickly the distance forward of the prop that air is being drawn across the fuselage/empennage. At idle speeds, the air being drawn into the propeller is slow moving and from a wide/broad area. Air volume in = Air volume out, but this isn't a ducted fan so the air velocity forward of the pusher-prop is likely of little consequence to aiding in drawing in cooling air.

PFGxe.gif
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Isn't that why he wants ducting?
 
Better performance than a Cirrus...you heard it here first...facepalm

 
Tantalum said:
I generally hate the argument "I just don't believe that" - but here I have to invoke it lol, I just don't believe that what was built and designed in the 1940-50s and is hand assembled out of sandcast molds with so much variability between engine to engine that we've reached peak performance. Maybe there is no money in improvement, but I bet you could squeeze a smarter piston power plant into a plane if you really tried. Maybe no one has tried because gains are limited and there's no financial prospect for it but it doesn't mean it's not possible

Let's see how the Otto people do.. they are also using a novel piston design. Granted it is diesel, but they have some lofty goals they're trying to hit. We'll see how close they can get
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Sorry...Im so late...forgot I was involved in this.

You dont have to believe it, it just is. Kind of like you dont have to believe in the earth being round, gravity or the moon landings either. But they are as well.

It comes down to this...we burn a fuel (100ll for most of us). This liquid contains some energy in its chemical bonds. We extract that energy thru controlled combustion in our engines. Well I should say we extract some of it. A lot...sometimes most...just turns into heat. The heat doesnt do any work, so for our purpose its wasted. You need to do work on the piston to push the crank to turn the prop. (Work is what scientists define as movement from a force acting on an object).

So from our fuel we get some heat (waste) and work (good) to spin the prop. Now in a given amount of 100ll there is only a certain amount of energy. Thats it, no more. If we can extract more of that energy to do more work we can use less fuel or make more power on the same fuel. The main way to do that is to increase compression ratio. If we could have compression ratios above 30:1 and up to 100:1 the efficiency of your engine could be ~50%. Most normal engines are around 15-25% now.

Try to do that ratio and not blow it up and be able to get it airborne. Ill wait.

So basically when someone says...."I dont know why we have to fly around with 70 year old technology...its got to be a way to make it so much better and efficient" there really isnt. Its kind of against the laws of the universe as we understand them. So your stuck with tiny increases in efficiency from things like computer controls, fuel injection, variable cam timing, cutting cylinders as needed, etc. Unless we find a better fuel or a really unique way to convert fuel into work...we are basically stuck in the 30-40s.

But we dont have to wear suits everywhere. Or fedoras. Although I kind of miss that part as I look good in a fedora and wear my dads Pendleton wool fedora when it rains.
 
ChemGuy said:
it just is
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That our 1950s designed engines that fail if you even look at them wrong are the epitome of engine tech?!?! I want whatever you guys are smoking.
 
ChemGuy said:
Sorry...Im so late...forgot I was involved in this.

You dont have to believe it, it just is. Kind of like you dont have to believe in the earth being round, gravity or the moon landings either. But they are as well.

It comes down to this...we burn a fuel (100ll for most of us). This liquid contains some energy in its chemical bonds. We extract that energy thru controlled combustion in our engines. Well I should say we extract some of it. A lot...sometimes most...just turns into heat. The heat doesnt do any work, so for our purpose its wasted. You need to do work on the piston to push the crank to turn the prop. (Work is what scientists define as movement from a force acting on an object).

So from our fuel we get some heat (waste) and work (good) to spin the prop. Now in a given amount of 100ll there is only a certain amount of energy. Thats it, no more. If we can extract more of that energy to do more work we can use less fuel or make more power on the same fuel. The main way to do that is to increase compression ratio. If we could have compression ratios above 30:1 and up to 100:1 the efficiency of your engine could be ~50%. Most normal engines are around 15-25% now.

Try to do that ratio and not blow it up and be able to get it airborne. Ill wait.

So basically when someone says...."I dont know why we have to fly around with 70 year old technology...its got to be a way to make it so much better and efficient" there really isnt. Its kind of against the laws of the universe as we understand them. So your stuck with tiny increases in efficiency from things like computer controls, fuel injection, variable cam timing, cutting cylinders as needed, etc. Unless we find a better fuel or a really unique way to convert fuel into work...we are basically stuck in the 30-40s.

But we dont have to wear suits everywhere. Or fedoras. Although I kind of miss that part as I look good in a fedora and wear my dads Pendleton wool fedora when it rains.
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Sorry, that was well written and I don't mean to be flip. My point is, we shouldn't stop innovation just under the assumption that what we have now is the best we can get.. we are limited by the physical chemical world, yes, hence my apprehension of there being some breakthrough battery technology.. but, there are incremental improvements that could be made to these engines. The economics of it might not be there but they're certainly not the end all be all internal piston combustion engines

People said diesel couldn't have a home in ga, but here we have the DA62 pulling 7 people through the air at 170-180 ktas burning 12-14 gph, combined! The C182 goes 30-50 knots slower carrying less and burning the same amount on one engine. Granted one is diesel and the other is gasoline, but it speaks to your point about these fossil fuels having only so much energy contained in them
 
3393RP said:
Everything PM said and did in this video is completely inconsequential to fixing the problems he has.
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Absolutely correct. The question is whether he understands that and is merely putting on a show until the inevitable hangar fire, and if not, what amazing world of denial is he dealing with? The whole thing is surreal at this point. Taping angle iron in front of the gear openings? Adding 50 pounds of mass in the cooling system as opposed to ducting air to his heat exchangers? I swear my 9 year old son wouldn't come up with worse solutions.
 
Does he mention the density altitude and humidity in comparing his two runs to 1k feet? How about air pressures in the tires? No scientific method whatsoever in his three “comparisons”


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kyleb said:
Adding 50 pounds of mass in the cooling system as opposed to ducting air to his heat exchangers?
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I asked him why he put the scoop on top, instead of the bottom, and he said, “because the radiator is on top”. It would’ve made way more sense to put the intake where the air is and route it to the radiator with scat tubing and shrouds... Too simple for Peter, I guess.
 
This guy has absolutely no clue on how to tune a Diesel engine. He’s just Willy nilly advancing timing and upping fuel.. what a MORON.

Then at the end his S4 engine crapped out and now he has no car. I wonder what DIY wonders he did to that thing.
 
Tantalum said:
Sorry, that was well written and I don't mean to be flip. My point is, we shouldn't stop innovation just under the assumption that what we have now is the best we can get.. we are limited by the physical chemical world, yes, hence my apprehension of there being some breakthrough battery technology.. but, there are incremental improvements that could be made to these engines. The economics of it might not be there but they're certainly not the end all be all internal piston combustion engines

People said diesel couldn't have a home in ga, but here we have the DA62 pulling 7 people through the air at 170-180 ktas burning 12-14 gph, combined! The C182 goes 30-50 knots slower carrying less and burning the same amount on one engine. Granted one is diesel and the other is gasoline, but it speaks to your point about these fossil fuels having only so much energy contained in them
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Two comments:
1) I've never argued that we couldn't build better (more reliable, easier to use) engines with current tech, only that there aren't great gains to be had in efficiency.
2) Diesel fuel has a higher energy density that 100LL (or any gasoline based fuel). That's why DA62 does so much better. (And a DA42 was on my "salivate-over" list for years!) In fact, diesel engines are a good match for aviation use: the tend to be very happy at steady RPMs, they tend to product high torque lower RPM solutions (so no reduction mechanism needed to direct drive a prop). Those are being kept out largely by economics. I do think you'd probably want a clean sheet design for airplane applications to get a really good solution, but theoretically it should work well.

John
 
Omalley1537 said:
Better performance than a Cirrus...you heard it here first...facepalm

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This video is just begging for parodies. I'm thinking of some examples:

Raptor vs. J-3 Cub: The Raptor accelerates faster than the Cub, but the Cub has a service ceiling greater than 400 feet MSL.

Raptor vs. Honda Trail 90: The top speed of the Trail 90 is lower than the Raptor, but you can ride it for more than 90 seconds without melting the cylinder head.

Raptor vs. Huffy bicycle: The Raptor is faster and can fly higher, but the Huffy has a greater useful load.


Edit to add: The one and only thing that his plane actually has enough of is horsepower. (Okay, two things: horsepower and ballast.) It doesn't have enough lift, stability, cooling, reliability, brakes, useful load, or anything else. But I think humans are naturally drawn to the easy things as a coping mechanism for difficult problems. So it isn't surprising to me that he went back to try to increase the engine power. That may be the only thing that he truly believes he can improve.
 
kyleb said:
Absolutely correct. The question is whether he understands that and is merely putting on a show until the inevitable hangar fire, and if not, what amazing world of denial is he dealing with? The whole thing is surreal at this point. Taping angle iron in front of the gear openings? Adding 50 pounds of mass in the cooling system as opposed to ducting air to his heat exchangers? I swear my 9 year old son wouldn't come up with worse solutions.
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What is that taped in front of the gear openings anyway? Like a stall strip to trip the boundary layer?
 
jsstevens said:
Two comments:
1) I've never argued that we couldn't build better (more reliable, easier to use) engines with current tech, only that there aren't great gains to be had in efficiency.
2) Diesel fuel has a higher energy density that 100LL (or any gasoline based fuel). That's why DA62 does so much better. (And a DA42 was on my "salivate-over" list for years!) In fact, diesel engines are a good match for aviation use: the tend to be very happy at steady RPMs, they tend to product high torque lower RPM solutions (so no reduction mechanism needed to direct drive a prop). Those are being kept out largely by economics. I do think you'd probably want a clean sheet design for airplane applications to get a really good solution, but theoretically it should work well.

John
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Yup, diesel would be my main focus if I were pursuing a GA replacement engine. Something that will happily loaf along at 2000rpm making gobs of torque with a miserly fuel burn (while burning cheaper Jet A). Continental makes several variants of them, FADEC and all. The problem (other than cost/conversion costs) is that they need the gearbox and the TBO times on the gearboxes are still being improved to live up to their AvGas counterparts.
 
Looks like he's still intending to go into production after he's done flying off the 40 hours. Completely insane, needs so much more than just flying it. But I don't see him getting close to 40 flight hours in it any time soon. You can only log taxi time if it's for the purpose of flight.

pm.png
 
231TC said:
Looks like he's still intending to go into production after he's done flying off the 40 hours. Completely insane, needs so much more than just flying it. But I don't see him getting close to 40 flight hours in it any time soon. You can only log taxi time if it's for the purpose of flight.

pm.png
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That's mildly terrifying.
 
231TC said:
Looks like he's still intending to go into production after he's done flying off the 40 hours. Completely insane, needs so much more than just flying it.
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Production of what? Even he couldn't probably replicate his prototype at this point. I'm sure he has no complete set of plans, showing all of his "fixes". What exactly does he intend to produce or sell to people. He couldn't sell you a brochure at this point.
 
midwestpa24 said:
Production of what? Even he couldn't probably replicate his prototype at this point. I'm sure he has no complete set of plans, showing all of his "fixes". What exactly does he intend to produce or sell to people. He couldn't sell you a brochure at this point.
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It’s just another sign of how disconnected from reality the fellow is regarding his project.
 
Salty said:
That's mildly terrifying.
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I have no doubt someone with some form of talent can take his carbon fiber shell and make it fly a complete pattern without completely melting down.
 
231TC said:
Looks like he's still intending to go into production after he's done flying off the 40 hours. Completely insane, needs so much more than just flying it. But I don't see him getting close to 40 flight hours in it any time soon. You can only log taxi time if it's for the purpose of flight.

pm.png
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When people build a Van's RV kit and talk about "flying off" their 40 hours, I am in the camp that thinks they're thinking about it wrong: It's 40 hours of test flying, so test things out. But even the most nonchalant kit builder would have to scoff at the Raptor simply "flying off" its 40 hours.
 
NordicDave said:
Anyone else scared off by the extreme turbulence of the string aerodynamic test? I'm not an aeronautical engineer, but don't think VG's will fix that nor were VG intended to fix a poor wing design.
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He taped a piece of aluminium angle in front of the giant void that is the landing gear well. He thought the landing gear well was causing roll oscillations in flight. This was after he thought the roll oscillations could have caused by thermals.

He really sounded deflated at the end and perhaps possibly finally coming to the realization it's not meant to be...that or completely out of cash and credit. Chasing more power when you can't keep the oil temp from running away as it is doesn't solve anything. He gets hung up on the trivial because he can't figure out the biggest problems. Heat and controllability. This comes back to him rushing and changing everything since the scale model phase. That and he's a software guy who probably has never actually built anything in his life.
 
Racerx said:
That and he's a software guy who probably has never actually built anything in his life.
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In fairness, he has now built something in his life. What he built is actually impressive in many ways. It may never be airworthy or safe, but it does exist and it did in fact fly under its own power. It is a complex enough design that I have said above and elsewhere that he clearly has CAD skills far greater than I ever will. There is a lot of good that can be said about him and his project.
 
iamtheari said:
In fairness, he has now built something in his life. What he built is actually impressive in many ways. It may never be airworthy or safe, but it does exist and it did in fact fly under its own power. It is a complex enough design that I have said above and elsewhere that he clearly has CAD skills far greater than I ever will. There is a lot of good that can be said about him and his project.
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No doubt Peter is smart. But he's also stubborn. Being stubborn isn't always a bad thing. Hell it's how we've gotten to where we are as a society in general. Someone saying someone is crazy and them being stubborn enough to figure it out and do it anyway. The problem is his approach to the problems that arise. Adding more coolant doesnt solve the overheating problem. Throw the idea away. What's it going to gain you? 2 more minutes before you're going nucular again. Lots of very wise people have given excellent advice. Someone who helped design the engine he uses told him to eliminate one turbo and he'd have less heat and more power. His response was it's really hard to do and didn't think it would work. Dismissing experts is where his stubbornness has gone. The carbon fiber shell is quite impressive from a distance. Everything works...sort of. The quality of the workings is suspect. His original goal was lofty. Is that still the goal?
 
Racerx said:
He gets hung up on the trivial because he can't figure out the biggest problems.
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I'm sure the guy is exhausted. He thought it was ready to fly last fall, then the Wasabi folks came out and identified a bunch of problems, some of which he fixed, some he didn't. Then he moved the airplane to Valdosta, where the airplane is less likely to kill someone on a test flight. So in the last year, his actual progress has been minimal. All the while, he's spending money, but he's not addressing the real concerns like the horror show of a power train.

I'm sure the aero issues can be solved. If he has a heavy wing, I'd bet some careful work with lasers, tape measures, and a digital level would identify the problem and he could correct it. The dutch roll? Rutan added vortilators at the leading edge on the main wing >30 years go. I think his aero issues are solvable. But I don't think his powerplant/PSRU is fixable. If he really needs 300+ HP, that little Audi engine isn't going to do that for very long.
 
Racerx said:
He taped a piece of aluminium angle in front of the giant void that is the landing gear well. He thought the landing gear well was causing roll oscillations in flight. This was after he thought the roll oscillations could have caused by thermals.

He really sounded deflated at the end and perhaps possibly finally coming to the realization it's not meant to be...that or completely out of cash and credit. Chasing more power when you can't keep the oil temp from running away as it is doesn't solve anything. He gets hung up on the trivial because he can't figure out the biggest problems. Heat and controllability. This comes back to him rushing and changing everything since the scale model phase. That and he's a software guy who probably has never actually built anything in his life.
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As someone who can't draw a straight line even with a ruler, I'm actually impressed with what Peter has done. I can however agree that he hasn't made very good decisions with his workarounds. Tunnel vision is a terrible thing but Peter isn't the first and certainly wont be the last person to tune out advice from others but in this situation it could cost him his life and that would be a tragedy, one of his own making, but a tragedy nonetheless.
 
I think a factor in his “troubleshooting” is that he is so far along in the development stage of this project that making the changes that have been recommended by those in the know would involve some significant about faces. In his mind, he has too much invested in time and money to make that something he is willing to do. He’s in a position where he feels he has to make what he’s got work. Not a good mindset to be in.
 
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