|
goatsestretchgoals posted:Someone touch the poop and tell him to put a box of used washers on his store.
|
#
?
Aug 9, 2021 22:08
|
|
|
|
| # ? Jun 5, 2024 20:39 |
|
|
How do you install install turbochargers backwards? Did he plumb it so they're dumping the compressed air out the exhaust or something?
|
|
#
?
Aug 9, 2021 22:27
|
|
|
I keep staring at diagrams and still can't make heads or tails of it. I think it's a combo sequential/twin turbo setup, with a pressure operated valve that allows turbo 1 to either feed or bypass turbo 2 on the cold side. Then on the hot side turbo 2 has some variable geometry turbine that does roughly the same thing. It's like someone at Audi was doing rails of coke off that RX-7 vacuum hose diagram when they came up with this.
|
|
#
?
Aug 9, 2021 22:49
|
|
|
azflyboy posted:How do you install install turbochargers backwards? I guess a better way of putting it is "out of order." He has a sequential twin-turbo setup with the goal of boosting more than a single turbo (rather than, say, feeding each bank of cylinders separately as in a parallel setup, or reducing lag as in the RX-7). One turbo feeds the next directly as a multi-stage compressor. This is how he plans to keep his car engine developing 300 horsepower at 25,000 feet, where there is only one-third as much air as at sea level. For his application the first turbocharger needs to be bigger than the second one. The big turbo moves a high volume of air at relatively low pressure and feeds the small one, which works on a small volume at high pressure. He has them installed the other way around. For a good explanation of why this sucks, we go to the aforementioned Audi engineer: quote:Hi Peter! quote:I first advised Peter to do this a year ago. My comment and subsequent ones by several other knowledgeable people were not just ignored, many were deleted. Peter is sure he has designed the turbos correctly and will not be swayed. Even by people who have been there and got the t-shirt. I do not know why he thinks the small turbocharger has to go first, but I would be interested to hear his justification. 
Sagebrush fucked around with this message at 23:16 on Aug 9, 2021 |
|
#
?
Aug 9, 2021 23:12
|
|
|
gently caress, if you have any idea how forced induction works that's obvious. I didn't realize Raptor man was that dumb.
|
|
#
?
Aug 9, 2021 23:19
|
|
|
Thanks for the explanation. I figured it was something like that, but the level of dumb with the project is high enough that I wouldn't have been surprised if he had plumbed them backwards somehow.
|
|
#
?
Aug 9, 2021 23:27
|
|
|
Now I sorta understand how forced induction in cars work, do you not need an intercooler to keep the heat of compressing the air from creeping into the cylinders? I get why the hot side is failing (gas doesn't expand enough to shed heat of compression) but this is a twin turbo diesel that somebody had built poorly and used it in an airplane
|
|
#
?
Aug 10, 2021 00:23
|
|
|
The kicker is that it’s going in an airplane where you don’t really care about low-RPM boost or turbo lag, so you can just stick the biggest turbo the engine can spin on there so you have the extra compressor capacity when ambient pressure goes down. Sequential turbocharging exists in aerospace, but it’s rare as gently caress, since a single big turbo is generally plenty until you go high enough that you’re probably using a turbine engine anyway.
|
|
#
?
Aug 10, 2021 01:21
|
|
|
Nebakenezzer posted:Now I sorta understand how forced induction in cars work, do you not need an intercooler to keep the heat of compressing the air from creeping into the cylinders? I get why the hot side is failing (gas doesn't expand enough to shed heat of compression) but this is a twin turbo diesel that somebody had built poorly and used it in an airplane You don't need an intercooler, but it greatly increases efficiency for not much money or effort. The primary goal is just to get more air into the engine and hot air has less air in it than cold air at the same pressure. It helps with cooling too, but not really enough that it should cause a problem*. *Not valid for people turbocharging things that weren't designed to be turbocharged and are already bumping up against the limits of their cooling system.
|
|
#
?
Aug 10, 2021 01:57
|
|
|
Staged superchargers were the bee’s knees from like nineteen forty to nineteen forty‐four. Outside of that, not so much.
|
|
#
?
Aug 10, 2021 02:00
|
|
|
My favorite is that he thinks this thing will do 300 KTAS with that engine when in reality he probably needs 2-3x the power for that kind of performance. Of course I have no doubt the plane would rip itself apart long before that speed is reached.
|
|
#
?
Aug 10, 2021 02:31
|
|
|
300ktas up there would only be ~200kias, so it’s not completely ludicrous. The ludicrous thing is not just making the Velocity work with a GTSIO-520 or something (which would probably still be over his head.) Something where he’s JUST doing airframe integration, instead of airframe integration and an entire power plant re-engineering project.
|
|
#
?
Aug 10, 2021 03:16
|
|
|
MrYenko posted:300ktas up there would only be ~200kias, so it’s not completely ludicrous. The ludicrous thing is not just making the Velocity work with a GTSIO-520 or something (which would probably still be over his head.) Something where he’s JUST doing airframe integration, instead of airframe integration and an entire power plant re-engineering project. Yeah I suppose that's fair. When you think about it his design takes all the uncertainty about flying like you'd get with a normal plane. You know you're going to crash 100% of the time so you can always be ready for it!
|
|
#
?
Aug 10, 2021 03:35
|
|
|
MrYenko posted:300ktas up there would only be ~200kias, so it’s not completely ludicrous. The ludicrous thing is not just making the Velocity work with a GTSIO-520 or something (which would probably still be over his head.) Something where he’s JUST doing airframe integration, instead of airframe integration and an entire power plant re-engineering project. For what it's worth, the Mooney M20 managed a top cruise speed of about 240kts on 280hp, so I'm thinking this would need more than 300hp to hit 300kts.
|
|
#
?
Aug 10, 2021 03:53
|
|
|
Ah but you're forgetting all the supersonic wave drag the Mooney has to deal with that the Raptor won't 
|
|
#
?
Aug 10, 2021 03:55
|
|
|
Sagebrush posted:Ah but you're forgetting all the supersonic wave drag the Mooney has to deal with that the Raptor won't “Am I a bad designer?” “No, it is the physicists who are wrong.” 
|
|
#
?
Aug 10, 2021 04:00
|
|
|
Need a raptor swag shirt of a guy holding controls as a monster made of re-used parts, overheating, and engine out lights sneaks up on him “Clever girl”
|
|
#
?
Aug 10, 2021 04:35
|
|
|
MrYenko posted:The kicker is that it’s going in an airplane where you don’t really care about low-RPM boost or turbo lag, so you can just stick the biggest turbo the engine can spin on there so you have the extra compressor capacity when ambient pressure goes down. Sequential turbocharging exists in aerospace, but it’s rare as gently caress, since a single big turbo is generally plenty until you go high enough that you’re probably using a turbine engine anyway. But if you just use another turbo, you can turbo normalize your turbo engine. Now it's at sea level all the time. Bing bong so simple. Here's the video where he explains his turbo setup. It really does a good job of documenting his engineering design tools: reading websites, Excel, CAD modeling. https://www.youtube.com/watch?v=Rh-ClOSuoEc
|
|
#
?
Aug 10, 2021 04:46
|
|
|
Platystemon posted:“Am I a bad designer?” 
|
|
#
?
Aug 10, 2021 04:49
|
|
|
That's from the lawsuit regarding the kid who was decapitated on the water slide in Kansas, by the way.
|
|
#
?
Aug 10, 2021 06:09
|
|
|
Sagebrush posted:That's from the lawsuit regarding the kid who was decapitated on the water slide in Kansas, by the way. Oh right. God drat
|
|
#
?
Aug 10, 2021 06:49
|
|
|
Am I remembering wrong, or is the Raptor way phatter than a Velocity XL? I remember someone made a frontal area comparison on homebuiltairplanes I think, specifically regarding claimed performance numbers and power required.
|
|
#
?
Aug 10, 2021 08:41
|
|
|
Xakura posted:Am I remembering wrong, or is the Raptor way phatter than a Velocity XL? I remember someone made a frontal area comparison on homebuiltairplanes I think, specifically regarding claimed performance numbers and power required. soon to be flatter 
|
|
#
?
Aug 10, 2021 12:14
|
|
|
The test flight video: https://www.youtube.com/watch?v=5gnEknj242M
|
|
#
?
Aug 10, 2021 13:39
|
|
|
Platystemon posted:“Am I a bad designer?”
|
|
#
?
Aug 10, 2021 14:13
|
|
|
Zero One posted:The test flight video: Oh man there’s an hour of this poo poo?  this guy is such a ding-dong!
hellotoothpaste fucked around with this message at 14:41 on Aug 10, 2021 |
|
#
?
Aug 10, 2021 14:39
|
|
|
I finally placed something that'd been bothering me forever. He's the old version of MzeoA guy!
|
|
#
?
Aug 10, 2021 14:44
|
|
|
“Now you could tie a few knots in it…” (door lever elastic band) “Now if you just disconnect the spring…” (control stick rebuild) Hahaha Peter is the worst, if these two weren’t there for testing he’d be dead already.
|
|
#
?
Aug 10, 2021 14:59
|
|
|
HookedOnChthonics posted:Collaborate with poor, doomed tom selfridge on a series of interesting pioneer era aircraft, then mostly give up on aviation in a huff when glenn curtiss very rudely decided to start turning profit? No drag, only lift. *scrapes across the beach*
|
|
#
?
Aug 10, 2021 17:44
|
|
|
Old but YouTube just recommend this to me: https://www.youtube.com/watch?v=sHMhClzfoi8 That's a big woopsie.
|
|
#
?
Aug 10, 2021 18:16
|
|
|
That's one way to get promoted to civilian
|
|
#
?
Aug 10, 2021 18:24
|
|
|
Zero One posted:Old but YouTube just recommend this to me: How it ended: https://www.youtube.com/watch?v=qC3zr0Ka-Ac https://www.youtube.com/watch?v=J7SE-0tD2HE
|
|
#
?
Aug 10, 2021 18:46
|
|
|
A guy I knew told a story about how he was ferrying a GA plane with someone. The other guy was setting up for a straight in to the airport, called runway in sight, was just about to flare, saw that the ramp was lined with fighter jets and started climbing again. Turns out his airport's runway was on the same heading as this one, except that it was several miles further down the runway heading. They gave him a number to call
|
|
#
?
Aug 10, 2021 21:30
|
|
|
Ola posted:How it ended: Missed opportunity to bust out the RATO rockets smdh
|
|
#
?
Aug 10, 2021 21:42
|
|
|
Ola posted:How it ended: the C-17 is supposed to be able to take off from a 3,500' runway and apparently runway 22 at KTPF is 3,580 feet long. i don't see the problem. it'd be pretty loving embarrassing for boeing if the plane couldn't do it. sheesh
|
|
#
?
Aug 10, 2021 21:45
|
|
|
Sagebrush posted:the C-17 is supposed to be able to take off from a 3,500' runway and apparently runway 22 at KTPF is 3,580 feet long. i don't see the problem. it'd be pretty loving embarrassing for boeing if the plane couldn't do it. sheesh The runway isn't built to handle its weight, so the wheels could actually push the runway surface into the ground, which would lengthen your takeoff roll somewhat.
|
|
#
?
Aug 10, 2021 21:51
|
|
|
Ola posted:The runway isn't built to handle its weight, so the wheels could actually push the runway surface into the ground, which would lengthen your takeoff roll somewhat. I thought the C-17 was built for operating off weak runways but I just looked up its ACN and its actually quite high at 80, compared to roughly 40 for a C-130 or a small airliner.
|
|
#
?
Aug 10, 2021 21:56
|
|
|
hobbesmaster posted:I thought the C-17 was built for operating off weak runways but I just looked up its ACN and its actually quite high at 80, compared to roughly 40 for a C-130 or a small airliner.
|
|
#
?
Aug 10, 2021 22:08
|
|
|
Typically you fly things on a C-17 because it's better than driving/shipping them. That C-17 was loaded when it landed, and had to be unloaded to take off. In addition to transporting the cargo, you also need to send the AF cops over to guard the stupid thing. And yeah, possibly have the runway inspected for damage.
|
|
#
?
Aug 10, 2021 22:23
|
|
|
|
| # ? Jun 5, 2024 20:39 |
|
|
Godholio posted:Typically you fly things on a C-17 because it's better than driving/shipping them. That C-17 was loaded when it landed, and had to be unloaded to take off. In addition to transporting the cargo, you also need to send the AF cops over to guard the stupid thing. And yeah, possibly have the runway inspected for damage. Wasn’t Mattis on board for that one?
|
|
#
?
Aug 10, 2021 23:31
|
|