|
Found an old video with a slight mishap on an ekranoplan: https://www.youtube.com/watch?v=CuEsR8DFjHI&t=28s. Not sure if it's a reboot or a refurbished oldie.
|
#
?
Mar 18, 2018 15:49
|
|
|
|
| # ? May 25, 2024 08:35 |
|
|
|
|
#
?
Mar 19, 2018 23:24
|
|
|
Oh my gently caress, that would be disconcerting to fly at first.
|
|
#
?
Mar 19, 2018 23:27
|
|
|
I want video proof that vehicle is actually capable of flight.
|
|
#
?
Mar 20, 2018 00:15
|
|
|
Looks like something designed and built by a 15 year old me in grade 10 shop class. The prop 
|
|
#
?
Mar 20, 2018 00:34
|
|
|
  http://www.barnstormers.com/eFLYER/2007/070600eFLYER.html
|
|
#
?
Mar 20, 2018 00:59
|
|
|
 it made the eFlyer!
|
|
#
?
Mar 20, 2018 01:14
|
|
|
It's like their first design goal was eliminating p-factor.
|
|
#
?
Mar 20, 2018 01:42
|
|
|
Safety Dance posted:It's like their first design goal was eliminating p-factor. It's been replaced with pucker factor.
|
|
#
?
Mar 20, 2018 04:07
|
|
|
Is that the fuel tank behind the cockpit? Those engines must be heavy as poo poo. Are aero engines noticeably lighter than automotive models making the same kind of power?
|
|
#
?
Mar 20, 2018 06:13
|
|
|
Yes, a lot of effort goes into making aero engines as light as possible
|
|
#
?
Mar 20, 2018 06:20
|
|
|
What's the tradeoff? Just shorter maintenance intervals? The standard 2,000-hour overhaul for a GA piston engine works out to like 90,000 miles in a car engine; certainly that's shorter interval than anyone would use for their car but also I bet the 2,000 hours is highly conservative. If you have two engines making the same power and one is noticeably smaller and lighter, that one will be under higher stress, all other things being equal. Sagebrush fucked around with this message at 06:29 on Mar 20, 2018 |
|
#
?
Mar 20, 2018 06:27
|
|
|
Just watched Last Flight of the Vulcan Bomber on Netflix and recommend it highly
|
|
#
?
Mar 20, 2018 06:58
|
|
|
Lycoming O-360 (Cessna 172): 180 HP @ 2700 RPM 117 kg dry 5.9 L displacement 8.5 compression ratio Toyota 2AR-FE (Camry): 180 HP @ 6000 RPM 147 kg wet 2.5 L displacement 10.4 compression ratio The æro engine is near the same weight for the same power, but it’s sweating a lot less to make it.
|
|
#
?
Mar 20, 2018 07:13
|
|
|
It's kinda fascinating that the aero engine has more than twice the displacement but weighs significantly less. Is it made from thinner, lighter castings? Or is it just that it doesn't have the water-cooling and all the accessories?
|
|
#
?
Mar 20, 2018 07:32
|
|
|
For some reason seeing that thing makes me imagine a Tomahawk reconfigured to carry human cargo like those ridiculous Polaris-launched jet sleds from Never Say Never Again.
|
|
#
?
Mar 20, 2018 07:42
|
|
|
What is this? I see it every time I take off from Amsterdam. The viewing area(?) in the nose has me confused.
|
|
#
?
Mar 20, 2018 11:26
|
|
|
Heliosicle posted:What is this? I see it every time I take off from Amsterdam. The viewing area(?) in the nose has me confused. SWAT etc training plane?
|
|
#
?
Mar 20, 2018 11:33
|
|
|
Platystemon posted:The æro engine is near the same weight for the same power, but it’s sweating a lot less to make it. This is the real difference between aircraft and automotive engines. Aircraft engines are designed to be run at or near maximum power and RPM for extended periods of time. Automotive engines spend most of their lives at or near idle, with occasional excursions to high throttle settings and high RPM. Aircraft engines have more similarities to race car engines than they do to production automotive engines, particularly in oiling. (And mostly because car racing owes a lot to the massive advances in aeronautical piston engines during WWII.)
|
|
#
?
Mar 20, 2018 11:38
|
|
|
Heliosicle posted:What is this? I see it every time I take off from Amsterdam. The viewing area(?) in the nose has me confused. These weird things come up from time to time in this thread; they are firefighting training devices. That way they don't need to burn an actual aircraft to train people.
|
|
#
?
Mar 20, 2018 11:44
|
|
|
Sagebrush posted:It's kinda fascinating that the aero engine has more than twice the displacement but weighs significantly less. Is it made from thinner, lighter castings? Or is it just that it doesn't have the water-cooling and all the accessories? Both, really. The problem is, the upper limit for aviation piston engines that are still being made tops out at something like 400hp.
|
|
#
?
Mar 20, 2018 11:58
|
|
|
mekilljoydammit posted:Both, really. The problem is, the upper limit for aviation piston engines that are still being made tops out at something like 400hp. Plenty of ship-of-Theseus Merlins and Wright 3350s (and a few PW 4360s) on the racing circuit though, and those bigass bastards make more than 1hp/cubic inch. The Lycoming that makes 180hp with 5.6L is dead-nuts reliable, I'll give it that. Engines that make actual power started as fighter engines and then got hot-rodded. Air racers have the same magic/tech secrets as NASCAR engine builders. And like NASCAR V8s, sometimes a cylinder head just fucks off to start a life on its own, which is not great for the engine. 
|
|
#
?
Mar 20, 2018 13:00
|
|
Bad Angus! Bad!
|
Sagebrush posted:I bet the 2,000 hours is highly conservative. It is, the most dangerous time in an aero engines life is the first few hundred hours when manufacturing and assembly problems are likely to present themselves. 2000 hours is pretty arbitrary, plenty of engines never make it that far and plenty run well past it.
|
|
#
?
Mar 20, 2018 13:29
|
|
|
mekilljoydammit posted:Both, really. The problem is, the upper limit for aviation piston engines that are still being made tops out at something like 400hp. Isn't that the general power range where turbine engines become more efficient, or at least not as crazy expensive in comparison?
|
|
#
?
Mar 20, 2018 13:42
|
|
|
Humphreys posted:SWAT etc training plane?
|
|
#
?
Mar 20, 2018 13:46
|
|
|
Delivery McGee posted:The Lycoming that makes 180hp with 5.6L is dead-nuts reliable, I'll give it that. They aren't that reliable. It's hard to provide a metric, because it's kind of hard to define reliability. A lot of engine failure accidents are caused by pilot error, fuel starvation and auxiliary systems. But there's still engine failures caused by well maintained internal components going boom.
|
|
#
?
Mar 20, 2018 14:43
|
|
|
Delivery McGee posted:Plenty of ship-of-Theseus Merlins and Wright 3350s (and a few PW 4360s) on the racing circuit though, and those bigass bastards make more than 1hp/cubic inch. The Lycoming that makes 180hp with 5.6L is dead-nuts reliable, I'll give it that. Engines that make actual power started as fighter engines and then got hot-rodded. Air racers have the same magic/tech secrets as NASCAR engine builders. And like NASCAR V8s, sometimes a cylinder head just fucks off to start a life on its own, which is not great for the engine. I mean, there's a reason why I said "still being made". The interesting thing if you do some digging is that... first off no, they don't have the same magic secrets as NASCAR engine builders because everyone is constrained by the original stuff. For example, Merlins, by any modern standards have absolute garbage heads, poo poo manifolds, and the valvetrain literally can't handle stiffer springs to deal with more cam timing... but there's no money in doing better and it would get into a mess trying to get improved stuff to fit under cowlings. The majority of what they're doing is just cramming more boost in. PT6A posted:Isn't that the general power range where turbine engines become more efficient, or at least not as crazy expensive in comparison? It's... hm. So, picking an example out of thin air, GE T700 turboshaft from a Blackhawk has a BSFC of 0.43-0.46lb/hp-hr which is pretty good, but not as good as an O-235, much less some modern diesels and more optimized gasoline engines - the old turbocompound R3350 was around 0.38 lb/hp-hr. Where turbines really come out ahead is power/weight though and lower part count... and basically most of the edge cases where a high power aviation piston engine would make sense got dwarfed by economy of scale of everything going to supporting turbines/jets. It's arguable a few decades ago that for something like a turboprop biz aircraft something like a 600-800ish horsepower piston engine twin would make sense, but then smaller jets got introduced so how many turboprop biz aircraft do you see?
|
|
#
?
Mar 20, 2018 14:45
|
|
|
PT6A posted:Isn't that the general power range where turbine engines become more efficient, or at least not as crazy expensive in comparison? Yeah, to get much more power than that out of a reciprocating engine you need to start running everything a lot hotter and harder and that makes things more expensive much more quickly. That said I'd love to see someone today build a 2,000 hp reciprocating aero engine using modern materials and tech. Then I want to put it in a Corsair or a Spitfire.
|
|
#
?
Mar 20, 2018 14:48
|
|
|
bewbies posted:Yeah, to get much more power than that out of a reciprocating engine you need to start running everything a lot hotter and harder and that makes things more expensive much more quickly. I mean, you could probably do a reliable-enough-for-Reno one out of modified GM LS stuff plus a turbo - I have one in an engine simulator I did a decade ago keeping to aviation piston speed guidelines and making about 2500hp. Devil's in the details of course.
|
|
#
?
Mar 20, 2018 14:53
|
|
|
mekilljoydammit posted:but then smaller jets got introduced so how many turboprop biz aircraft do you see? TBMs, PC-12s, King Airs, Piper Meridians, Cessna Denalis in the near future, so... a lot?
|
|
#
?
Mar 20, 2018 15:16
|
|
|
PT6A posted:TBMs, PC-12s, King Airs, Piper Meridians, Cessna Denalis in the near future, so... a lot? Hm, ok. I know there were a few attempts to do piston engine competitors but none of them ever panned out very successfully; if I can't point at the mini-bizjet things I'm not exactly sure what I can point at as to why everyone stopped trying, other than past a point if every other attempt hasn't panned out who wants to be the next one? Quick googling suggests the Orenda V8 is slightly less dead than I thought (in a user/post combo they were trying to compete with the PT6 series) but who knows, I'll believe it when I see it.
|
|
#
?
Mar 20, 2018 15:23
|
|
|
My hunch would be that turboprops are superior to piston engines for anything beyond the smallest applications, so they've largely replaced them, but turbofans are only superior to turboprops for specific mission profiles, which is why the two exist side by side.
|
|
#
?
Mar 20, 2018 15:30
|
|
|
gee bee jelqed
|
|
#
?
Mar 20, 2018 15:39
|
|
|
One of the biggest problems with an automotive engine in an aeronautical application is engine output speed. You’re RPM limited at the prop by prop tip speed, and since auto engines often make power at 5-6000rpm means you have to have a rather substantial (Heavy) reduction gearbox. Even geared radial and opposed engines top out under 3000rpm at the crank, made possible by much larger displacements.
|
|
#
?
Mar 20, 2018 15:40
|
|
|
Well, the Sabre was up around 3800-4000rpm but sure. Of course it's not like turbines don't have reduction gearboxes too...  I suspect one of the big things is just relative maintenance. There's a lot fewer wear parts in a turbine.
|
|
#
?
Mar 20, 2018 15:45
|
|
|
 
|
|
#
?
Mar 20, 2018 15:58
|
|
|
It's also about power density. A PT6 can be rated from 300-1200SHP, with the differences, if any, coming in the gearbox. The differencea between 150HP and 600HP piston engines is going to be significant, usually adding cylinders, turbos, maybe a supercharger, and intercoolers. Also, turbines are really well-suited to sitting behind constant-speed propellers, as their torque curve is very spiky.
|
|
#
?
Mar 20, 2018 16:02
|
|
|
I'm suddenly more concerned about tail strikes than usual
|
|
#
?
Mar 20, 2018 16:05
|
|
|
PT6A posted:My hunch would be that turboprops are superior to piston engines for anything beyond the smallest applications, so they've largely replaced them, but turbofans are only superior to turboprops for specific mission profiles, which is why the two exist side by side. Yeah, a turbine has a few spinning parts and that's it, all the other parts can be made redundantly. A reciprocating engine has some real lovely vibrations and wear & tear going on compared, in addition to having a lot more constantly moving parts, so there's a lot more parts that get to act as a single point of failure. I wouldn't be surprised in the least if many of the piston engines in use aren't in use because they're better to operate, but because they're cheaper to own and maintain when not in use constantly, and for a privately owned vehicle that's usually more important than 24/7 fuel efficiency and minimizing maintenance downtime.
|
|
#
?
Mar 20, 2018 16:16
|
|
|
|
| # ? May 25, 2024 08:35 |
|
|
PT6A posted:Isn't that the general power range where turbine engines become more efficient, or at least not as crazy expensive in comparison? Pretty sure whether jets or rotary engines are more efficient is a function of airspeed and altitude.
|
|
#
?
Mar 20, 2018 16:22
|
|
