Raptor Aircraft

FastEddieB said:
This is apparently an inherent problem to overcome in any pusher design - pretty obvious as there’s no “fan” out front to enhance cooling while stationary or at low speeds.
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Can confirm. I got stuck waiting for a takeoff clearance in Sanford, FL in June. After 15 minutes, I was about to taxi back to the FBO to let the oil cool down. It was just over 200F. PM would have said "I'm okay with that". :D
 
donjohnston said:
Can confirm. I got stuck waiting for a takeoff clearance in Sanford, FL in June. After 15 minutes, I was about to taxi back to the FBO to let the oil cool down. It was just over 200F. PM would have said "I'm okay with that". :D
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For oil cooling, I would think a fan over the cooler would be pretty effective. Does it get in the way too much for forced cooling or something?
 
Well that's finally a major improvement in something important. I'm kinda confused how he was "replicating the conditions of the last flight" by doing everything completely different, but cheers to him for positive progress.
 
Now he just needs to find a way to add about 100 hp and slice about 1,000 lbs off the empty weight. At this point, it really needs either a PT-6 or RR250.
 
Salty said:
For oil cooling, I would think a fan over the cooler would be pretty effective. Does it get in the way too much for forced cooling or something?
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I only know of one Velocity that did that. I wouldn't think it would make that much difference.

I will say that one time sitting in 98F heat for 15 minutes was the only time I've had a problem with high oil temps.
 
Yeah, I think first flight on that one has happened recently or is about to.

There's a single turboprop in Texas that's been flying for a while. It sounds very nice.
 
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Velocity173 said:
The V-twins are really taking off. When I dropped my V173 off for condition inspection in 2011, the prototype was being built. Now they’ve got a dozen or more flying. I like the V-twin but I’d really like to have a turbine version. Just not sure the fuel burn justifies the cost.
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Yeah I'd really think that pressurization would be a requirement if I was going kerosene burner, otherwise you don't get to really use most of the advantage of the powerplant.

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Stall testing? We don’t need no stink’in stall testing!
 
What’s the extra weight that he’s carrying that would only allow a 600-700 fpm climb rate?
 
Velocity173 said:
The V-twins are really taking off. When I dropped my V173 off for condition inspection in 2011, the prototype was being built. Now they’ve got a dozen or more flying. I like the V-twin but I’d really like to have a turbine version. Just not sure the fuel burn justifies the cost.
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Cost justification gets very difficult with anything related to aviation.. as much as I dream of the turbine version I think I'll be relegated to piston for the foreseeable future.. (if only I had poured all my savings into GameStop a few weeks ago!)


SoonerAviator said:
Yeah I'd really think that pressurization would be a requirement if I was going kerosene burner, otherwise you don't get to really use most of the advantage of the powerplant.

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Is the turbine Bonanza conversion and 210 conversion pressurized?
 
Tantalum said:
His ego

Sorry but that was too easy
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He says he pleased with these climb rates and that it’s no “rocket ship RV.” Well, how does he plan on getting to the FLs on 600-700 fpm? And those numbers are just him on board and down low.

Says his next flight will explore cruise speed up at 5,000 ft. I still predict around 160 true. I noticed he took the PFD off the screen this last flight as well. Perhaps not wanting to show his fuel burn and TAS from his YT viewers.
 
Velocity173 said:
He says he pleased with these climb rates and that it’s no “rocket ship RV.” Well, how does he plan on getting to the FLs on 600-700 fpm? And those numbers are just him on board and down low.

Says his next flight will explore cruise speed up at 5,000 ft. I still predict around 160 true. I noticed he took the PFD off the screen this last flight as well. Perhaps not wanting to show his fuel burn and TAS from his YT viewers.
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What's funny is he kept comparing this thing to a Cirrus. A Cirrus vs RV10 are really close.
 
Muller's supposition that the inlets and outlets of the cowling are operating at a "vacuum" reveal just how ridiculous his thought processes are. He still hasn't tried to measure ∆T through the cowling inlet and outlets. He hasn't tried using manometers to measure ∆P across heat exchangers or the cowling as a whole. His conclusions about the effectiveness of the changes being made are nonsense³.

Then it's revealed he had the radiator fabricated to fit the space available, and since the area was less than that of the Audi car radiator, it was made deeper to match the volume. Again Muller's logic is deeply flawed.

As air passes through a radiator, it absorbs heat. But at some point, making the radiator thicker doesn't provide any further heat transfer. Without calculating the optimum core depth based on ambient and coolant temps, airflow, fins per inch, tube size, and pressure drop, any depth beyond the effective maximum just increases ∆P and drag.

Muller is convinced he has conquered the problem. He's not even close.
 
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Tantalum said:
Cost justification gets very difficult with anything related to aviation.. as much as I dream of the turbine version I think I'll be relegated to piston for the foreseeable future.. (if only I had poured all my savings into GameStop a few weeks ago!)



Is the turbine Bonanza conversion and 210 conversion pressurized?
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Bonanza no, 210's mostly yes but some not. So I'm told.
 
3393RP said:
Muller's supposition that the inlets and outlets of the cowling are operating at a "vacuum" reveal just how ridiculous his thought processes are. He still hasn't tried to measure ∆T through the cowling inlet and outlets. He hasn't tried using manometers to measure ∆P across heat exchangers or the cowling as a whole. His conclusions about the effectiveness of the changes being made are nonsense³.

Then it's revealed he had the radiator fabricated to fit the space available, and since the area was less than that of the Audi car radiator, it was made deeper to match the volume. Again Muller's logic is deeply flawed.

As air passes through a radiator, it absorbs heat. But at some point, making the radiator thicker doesn't provide any further heat transfer. Without calculating the optimum core depth based on ambient and coolant temps, airflow, fins per inch, tube size, and pressure drop, any depth beyond the effective maximum just increases ∆P and drag.

Muller is convinced he has conquered the problem. He's not even close.
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There you go using thermodynamics instead of TLAR engineering......
 
Let’s see, experimental plane, test flight, unknow noise and vibration, and he never even thought of maybe declaring and emergency? Great test plan again.
 
He opened the video with, "The purpose of this flight was to take the aircraft up to around about 4 or 5 thousand feet...." That dude has no solid flight test plans.

Personally, I probably would have declared an emergency or at least told tower there was an issue. But he handled it well enough. He's the type who probably wouldn't even declare an emergency if he was on fire, though.
 
231TC said:
He opened the video with, "The purpose of this flight was to take the aircraft up to around about 4 or 5 thousand feet...." That dude has no solid flight test plans.

Personally, I probably would have declared an emergency or at least told tower there was an issue. But he handled it well enough. He's the type who probably wouldn't even declare an emergency if he was on fire, though.
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"I've got flames coming out of the back, so the afterburner appears to be working. I don't remember installing one though"

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I watched a couple of the darkaero videos yesterday and man what a difference..
 
231TC said:
He opened the video with, "The purpose of this flight was to take the aircraft up to around about 4 or 5 thousand feet...." That dude has no solid flight test plans.

Personally, I probably would have declared an emergency or at least told tower there was an issue. But he handled it well enough. He's the type who probably wouldn't even declare an emergency if he was on fire, though.
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He's technically a software developer by trade, right? I imagine he's the type who classifies bugs as features and blames an obviously defective UI on the users.. we had a developer who loved designing things with double negatives "disable background check requirement" instead of "require background check" .. of course this meant that about 30% of the people selecting that button were using it incorrectly..
 
231TC said:
He opened the video with, "The purpose of this flight was to take the aircraft up to around about 4 or 5 thousand feet...." That dude has no solid flight test plans.

Personally, I probably would have declared an emergency or at least told tower there was an issue. But he handled it well enough. He's the type who probably wouldn't even declare an emergency if he was on fire, though.
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LiveATC caught PM's full callup to ATC, in which he acknowledged "I have a slight rattle in the back that's annoying me." Curiously, he edited that part out for the video.

https://archive.liveatc.net/kvld/KVLD-Jan-30-2021-2100Z.mp3

That's at the 10:25 mark. BTW, if you back up to 5:55, you'll also hear VLD Tower's (quite prudent) precaution ahead of the flight...
 
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Racerx said:
What's funny is he kept comparing this thing to a Cirrus. A Cirrus vs RV10 are really close.
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The estimated climb rate at sea level was 1600+ ft/min. That’s from the web page that compares the Raptor’s estimated performance with a Cirrus SR22. The same web page estimated the stall speed at 65 knots and empty weight at 1800 lbs.

I would want to investigate which of my assumptions in the simulations that led to the performance estimates being that far off. It could be that new data from actual flights could allow for better performance calculations and refinements before the next prototype is built.

flightwriter said:
LiveATC caught PM's full callup to ATC, in which he acknowledged "I have a slight rattle in the back that's annoying me." Curiously, he edited that part out for the video.

https://archive.liveatc.net/kvld/KVLD-Jan-30-2021-2100Z.mp3

That's at the 10:25 mark. BTW, if you back up to 5:55, you'll also hear VLD Tower's (quite prudent) precaution ahead of the flight...
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He may have edited that out of the video because it was so over-modulated that it melted the camera that the audio panel recordings go into.
 
flightwriter said:
LiveATC caught PM's full callup to ATC, in which he acknowledged "I have a slight rattle in the back that's annoying me." Curiously, he edited that part out for the video.

https://archive.liveatc.net/kvld/KVLD-Jan-30-2021-2100Z.mp3
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That's the second flight with the rattle, not the one from the latest video. Strange that he just says it's "annoying" him. It's more than annoying when your plane is falling apart and you don't know what the problem is. Bad practice to downplay things like that. Controllers can't read minds (although some of the better ones almost can). He should take things like this more seriously.

flightwriter said:
BTW, if you back up to 5:55, you'll also hear VLD Tower's (quite prudent) precaution ahead of the flight...
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Yeah, I've noticed them doing that on a couple previous flights, too. In one of the videos he commented on it and mentioned he didn't know why, he hadn't asked for it. He seemed a little offended.
 
iamtheari said:
The estimated climb rate at sea level was 1600+ ft/min. That’s from the web page that compares the Raptor’s estimated performance with a Cirrus SR22. The same web page estimated the stall speed at 65 knots and empty weight at 1800 lbs.
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I noticed today that if one was able to overlay the view out front of the Raptor on final with a similar video looking outside a 737, the approach looks to be at the same speed.
 
Wait, so parts of the carbon fiber are coming apart and rattling? Isn't that exactly what the Wasabi guys pointed out? Portions of the plane coming apart?
 
Tantalum said:
Wait, so parts of the carbon fiber are coming apart and rattling? Isn't that exactly what the Wasabi guys pointed out? Portions of the plane coming apart?
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I think they found some delamination. And I think this was not delamination. It sounded like it was a piece that he had glued into place and that glue failed. Different than actual delamination, in my limited understanding of composite construction techniques.
 
iamtheari said:
I think they found some delamination. And I think this was not delamination. It sounded like it was a piece that he had glued into place and that glue failed. Different than actual delamination, in my limited understanding of composite construction techniques.
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That was my concern from the videos of the Wasabi guys inspection. Anytime they found something, out popped the epoxy and any material he could find to fix it. The one that stood out was when the rudder pedal would bind or hang up. Instead of finding the reason for the bind, his solution was to epoxy a chunk of wood under the pedal to limit the travel from reaching that point.
 
midwestpa24 said:
That was my concern from the videos of the Wasabi guys inspection. Anytime they found something, out popped the epoxy and any material he could find to fix it. The one that stood out was when the rudder pedal would bind or hang up. Instead of finding the reason for the bind, his solution was to epoxy a chunk of wood under the pedal to limit the travel from reaching that point.
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It wasn't binding. It was hitting the fuselage beyond a normal rudder range of motion...if memory serves.
 
Racerx said:
It wasn't binding. It was hitting the fuselage beyond a normal rudder range of motion...if memory serves.
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Whatever the cause, I just thought the idea of, here's a random block of wood, lets glue it to the floor under the pedal, seemed kind of slapped together.
 
midwestpa24 said:
Whatever the cause, I just thought the idea of, here's a random block of wood, lets glue it to the floor under the pedal, seemed kind of slapped together.
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It is kind of slapped together, but that one doesn't offend me. The pedal traveled too far. A travel limit was needed. A block of wood glued into place is a reasonable way to solve that in the prototype, and then he can design improvements in the control system including travel limits into the second prototype or production line.

There are places where just throwing things together is unacceptable, but this one didn't cross the line for me. "Better is the enemy of good enough" and the wood block is good enough. Cooling is the biggest, closest threat to a successful project, and I think he is wise to focus on that.
 
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