Russian PAK-TA concept question
Russian PAK-TA concept question
(OP)
Hi all,
first off, I am NOT an engineer (hope that's not a problem). But I do have a question, in case any of you could spare a minute or two to explain something to me.
Is it physically possible for a fan (any type of fan), to produce supersonic airflow? I'm by no means an expert on this, but for some reason I feel like this shouldn't be possible. If the intake ducts on a supersonic jet need to be designed to slow the incoming air to subsonic speeds so that the compressor can handle it, it doesn't seem logical to me that any fan by itself should be able to accelerate air to supersonic speed.
The reason I'm asking is because of the recently announced russian "PAK-TA" transport aircraft. There are many things that seem illogical and borderline ridiculous about this "concept" (apparently expected to enter service within 10 years... or not), but the one that struck me as the most asinine was that it is apparently supposed to use electrically driven fans to produce the necessary thrust to reach Mach 1.8... with a 200-ton payload. That and I'm pretty sure that the wing tips would collide with the shock wave coming off the nose at supersonic speed. It seems only logical to me that the entire concept is merely propaganda and will never get past the stage of being a 3D model, but I'd like to have some sort of scientific proof to back this up.
Can any of you help me out?
first off, I am NOT an engineer (hope that's not a problem). But I do have a question, in case any of you could spare a minute or two to explain something to me.
Is it physically possible for a fan (any type of fan), to produce supersonic airflow? I'm by no means an expert on this, but for some reason I feel like this shouldn't be possible. If the intake ducts on a supersonic jet need to be designed to slow the incoming air to subsonic speeds so that the compressor can handle it, it doesn't seem logical to me that any fan by itself should be able to accelerate air to supersonic speed.
The reason I'm asking is because of the recently announced russian "PAK-TA" transport aircraft. There are many things that seem illogical and borderline ridiculous about this "concept" (apparently expected to enter service within 10 years... or not), but the one that struck me as the most asinine was that it is apparently supposed to use electrically driven fans to produce the necessary thrust to reach Mach 1.8... with a 200-ton payload. That and I'm pretty sure that the wing tips would collide with the shock wave coming off the nose at supersonic speed. It seems only logical to me that the entire concept is merely propaganda and will never get past the stage of being a 3D model, but I'd like to have some sort of scientific proof to back this up.
Can any of you help me out?





RE: Russian PAK-TA concept question
http://www.grc.nasa.gov/WWW/k-12/airplane/nozzled....
The SR-71, for instance, used variable inlets and nozzles to decelerate incoming air from Mach 3 to subsonic speed, heat it up, and spit it back out, at a net acceleration by the time it left the nozzle.
http://www.enginehistory.org/Convention/2005/Prese...
Details? Ask someone who got further than undergrad aerodynamics.
The mach cone at 1.8 (1200 mph ground speed) Mach would I think be 41 degrees each side, so included angle of 82 degrees.
I think it looks cool, but pop sci still slams it like a propaganda rag.
http://www.popsci.com/look-ridiculous-russian-supe...
RE: Russian PAK-TA concept question
Well, I'm going to take a punt and say yes, because an airfoil can operate supersonically
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Russian PAK-TA concept question
sure, a propeller can operate with the tips travelling at supersonic speed, but can it accelerate the air it moves past Mach 1?
RE: Russian PAK-TA concept question
Cheers
Greg Locock
New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?
RE: Russian PAK-TA concept question
TTFN

FAQ731-376: Eng-Tips.com Forum Policies
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers
Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com: http://www.engineering.com/AskForum/aff/32.aspx
RE: Russian PAK-TA concept question
RE: Russian PAK-TA concept question
" I suppose it could be possible for the air to be accelerated to supersonic speed while being forced through a duct with gradually reduced diameter, but I can't imagine that being an efficient way of producing thrust."
Pretty much every jet engine uses the deLaval nozzle principle to accelerate airflow to supersonic speed
RE: Russian PAK-TA concept question
another day in paradise, or is paradise one day closer ?