Ramjet engine = Hypersonic?

Question???

What do you believe the top speed for the Ramjet engine is?

Do you think the SR-71 going Mach 4 was as heigh as it can go? or do you think it can go hypersonic?



[edit on 11-12-2004 by Murcielago]

I heard stories of the SR-71 hitting Mach 4 pushing it to its limits but these were not proven or documented so I dont know if its true. I never heard any story of it going Mach 5 though , even Mach 3+ is amazing IMO for the time that the SR-71 was created.

I still want to know what the ceiling of the darn thing is 100,000+ is all we get Whats with the secrets on a retired plane shouldnt we have exact numbers now

I ask this because I found a US patent # 6,672,068 B1 that says if you change the config of the engine and intake in-flight then you would be able to go up to Mach 12! As you know ramjets can take-off on a normal runway (unlike a scram-jet), This aircraft would have some amazing capabilities.

WoW that would be amazing if they could reach those speeds with a ramjet. For the scramjets we have tested dont they start them off with rocket engines to get them up to speeds were the scramjet can kick in?

If they could reach Mach 12 taking off from a runway with a Ramjet that would be amazing and better then a scramjet I would think.

I remember one design NASA had for the SR-71s they got were they would put a third engine on it I forgot how fast they thought it would go, They never built it

[edit on 11-12-2004 by ShadowXIX]

Found some info on that NASA SR-71. They were going to strap a areo spike rocket engine on it

Still looking into how fast they though it would go

www.dfrc.nasa.gov...

What do you mean, they were going to...They did.

Originally posted by Murcielago
As you know ramjets can take-off on a normal runway (unlike a scram-jet), This aircraft would have some amazing capabilities.

WRONG.

Ramjets don't produce "static" thrust because they don't have any way to compress air to engine.
Blackbird uses turboramjets which are like turbojet inside ramjet.

www.aerospaceweb.org...


Here's one interesting page about different methods of air breathing propulsion.
www.dcr.net...

Truely awesome links!! Thanks very much! So the SR-71 is TurboRamjet , they say that the ramjet engine has low efficiency below mach 3, so by starting the Ramjet at mach 3 will the turboramjet engine be able to reach its maximum efficiency by accelerating to its optimum velocity. Can a ramjet engine accelerate further without increase in fuel consumption? What is the Air- fuel ratio of a ramjet ? How does the fuel consumption of a ramjet engine compare with that of a standard turbojet if a turbojet could travel at the same speeds ?

Originally posted by Murcielago
I ask this because I found a US patent # 6,672,068 B1 that says if you change the config of the engine and intake in-flight then you would be able to go up to Mach 12! As you know ramjets can take-off on a normal runway (unlike a scram-jet), This aircraft would have some amazing capabilities.

Don't believe everything you read... That may have not been tested yet, so very well may be false. Also, the engine may be able to go Mach 12, but the aiframe would more than likely not.

ah, thanks for correcting me.

New question: What is the difference between a ramjet and a scram-jet? and please dont tell me that the only difference is its name changes once its capable of reaching mach 5.

cmdrkeenkid - Its from an obviously credible site, I know this doesn't mean one is flying around right now, but to get a patent I believe patent office needs a lot of proof that it does work the way you say.( and by proof i'm not talkin about a experimental aircraft)
Also, They have airframes that could withstand the heat, and i'm not talkin about fragile tiles.

a scram jet engine is better than a ram jet engine because

in a Ramjet engine, the air is rammed into a tight space so quickly, that it actually compressess itself, this provides massive acceleration, possibly to Mach 6, but since the air rushes in so fast, the temperature quickly rises to about 6000 degrees ferenheit which makes the aircraft slow big time

on the other hand, a scramjet engine

it can reach Mach 20-25 and it also solved the poverheating problem, but, a brand-new problem was created, something to deal with air mixing with the fuel, which results in a spark, and the eventual explosion of the aircraft, but they have found a way around this problem as well, although its classified

here's a link of a short description of each

www.area51zone.com...

Originally posted by Dima
..but they have found a way around this problem as well, although its classified

here's a link of a short description of each

www.area51zone.com...

One question: IF its classified how do you know about it?
Nice link BTW :

Originally posted by Murcielago
New question: What is the difference between a ramjet and a scram-jet? and please dont tell me that the only difference is its name changes once its capable of reaching mach 5.

Scramjet means supersonic combustion ramjet.

In ramjet airflow has to be slowed to subsonic speed before entering "burning chamber", this also increases internal drag on engine.
Second link in my previous post states reason to it nicely: "And even a ramjet must have subsonic air inside; supersonic airflow would disrupt the combustion pattern in the flame holders, literally blowing out the fire."

In scramjet it's not necessary to slow airflow to subsonic which also gives advantage of smaller internal drag.
But starting scramjet requires very high supersonic speed, meaning in practise hypersonic speed.
Scramjets also require shaping of aircraft bottom to such that it does big part of compressing air for engine.

en.wikipedia.org...

Originally posted by Dima
but, a brand-new problem was created, something to deal with air mixing with the fuel, which results in a spark, and the eventual explosion of the aircraft...

Nope, proplem isn't explosion, it's just that because air flows through engine supersonically fuel has to burn very fast, otherwise burning wouldn't happen anymore inside engine increasing speed of outflowing air.
Solution to this is to use fuels which burn faster.

Originally posted by cmdrkeenkid
Don't believe everything you read... That may have not been tested yet, so very well may be false.

Yeah, fact that something is patented in US doesn't guarantee anything.
I'm currently waiting how long it takes until someone patents breathing.

My question is, how will a scramjet get up to the optimum point where it can start? the x-43 used a pegasus rocket to get to its required altitude and velocity , but on an operational plane this would negate the reasons for choosing the Scram jet in the first place. Would an operational craft use a urboRamjet/scramjet combonation where the craft usses two of each kind and certain engines are stopped or started during various phases of the flight?

Originally posted by roniii259
My question is, how will a scramjet get up to the optimum point where it can start? the x-43 used a pegasus rocket to get to its required altitude and velocity , but on an operational plane this would negate the reasons for choosing the Scram jet in the first place. Would an operational craft use a urboRamjet/scramjet combonation where the craft usses two of each kind and certain engines are stopped or started during various phases of the flight?

For a scramjet craft you could make it a hybrid and put a rocket motor on it or PDE, But of course the more you throw on it the heavier and slower and shorter range it will have. I think the turbojet engine that goes mach 4+ should then drop the scram craft. Sure it would be a 2-stage operation, but I think its the best choice.

E_T:

re: air flow and combustion.

The other solution is to slow the air down inside the engine prior to it burning.

picture this (the * reprsents the inside of the combustion chamber, --> is direction of air flow)

--> ==

hard to do in ascii text, but small inlet, wide internal area for combustion, small exhaust nozzle.

You probably already knw that, but included for the sake of completeness for the discussion.

Osiris

Originally posted by otlg27
hard to do in ascii text...

[*code*]content[*/code*] tag helps little because it prevents software from modifying its content. (without *s)

yo IAI, how come i know about it, i don't, ithe article said that it was classified