Forum: Technology

Well how about it guys..... Cheers

I think I'd go with a new generation turbojet and SCRAM-jet configuration.
(Supersonic Combustion RAM)

Say 3 turbojets horizontally arranged across the aft portion of the airframe with 2 SCRAM-jets spaced between the turbojets.

TSTST

Use a retractable type inlets to feed the turbojets at slow speeds, then use them to control the inlet-shock at higher MACH until the SCRAMS fully kick in and you can kill the turbojets completely...?

My alternate/future improvement would be to use a Pulse Detonation Engine (PDE) in place of the center turbojet loosing the outboard turbojets.

SPS

For a "simpler" configuration without the weight/complexity of the inlet system you could use a rocket for boost/landing. A rocket designed to use JP-7 over a wide range of throttle settings, maybe with a variable nozzle?

SRS

Anyone.... Anyone.... Anyone....

Keep 'em flyin' Thumb

TEG

F-16.net Sponsor

Hey TEG, your idea is not a bad one, but I believe they are working on something very similar to that----> check out this popsci article.

http://www.popsci.com/military-aviation ... c-age-near

Salute

Looks like DARPA beat you to it, TEG.

OTOH, funding was a problem and demo vehicle cancelled.

Finally, does anyone REALLY BELIEVE the program went away?

We gotta get parrot-cranium up to Groom Lake to gather intell, huh?

Gums sends ...

Wish I could go on sabbatical near Groom Lake.... Cool

I thought Reaction Engines Limited had an interesting idea on how to go from rest to mach 5 with their Scimitar engine concept.

http://www.reactionengines.co.uk/lapcat_scim.html

I don't know how close this is to being a reality, though.

Kryptid wrote:

I thought Reaction Engines Limited had an interesting idea on how to go from rest to mach 5 with their Scimitar engine concept.

http://www.reactionengines.co.uk/lapcat_scim.html

I don't know how close this is to being a reality, though.

Wow does that seem overly complicated!?!

Using "heat exchangers in the main thermodynamic cycles" to "cool down the air to the vapour boundary and avoid liquefaction"...

So they're chilling air until it's almost a liquid then pumping it at extreme high pressure into a rocket to use it as the oxidizer....

I would think the weight penalty of all that turbo - machinery would be higher than a conventional rocket installation with conventional fuels.

Interesting concept though..... I'll stick with a couple F119s for boost Cool

Keep 'em flyin' Thumb

TEG

IMHO, the question is, for the 21st century...what will replace the jet engine;
that is, the aero gas turbine? Whatever country or region can come up with
a viable alternative to turbine engines in aircraft, will have a tremendous
tactical advantage. Now, to be realistic, I am not talking about Star Wars
anti-gravity stuff here, but real tech for the 21st century. You have to think
that brass in the USAF have been thinking about this for sometime. Sure
would be nice to cruise at say 1,000 mph for over an hour or more in a stealthy,
agile fighter-sized craft? May be a combined cycle approach? How about
an ultra high compression (pressure ratio) turbine that can automatically shift
from a pure turbojet to a turbofan depending upon Mach number and altitude?
I would REALLY be impressed if a government and/or private firm can make
a propulsion system without the need to burn something! Now that would be
impressive. Again, what if anything will replace the *conventional* jet engine
in the 21st century is the $64,000 question IMO. The first to do this wins...

jetblast16 wrote:

IMHO, the question is, for the 21st century...what will replace the jet engine;
that is, the aero gas turbine? Whatever country or region can come up with
a viable alternative to turbine engines in aircraft, will have a tremendous
tactical advantage. Now, to be realistic, I am not talking about Star Wars
anti-gravity stuff here, but real tech for the 21st century. You have to think
that brass in the USAF have been thinking about this for sometime. Sure
would be nice to cruise at say 1,000 mph for over an hour or more in a stealthy,
agile fighter-sized craft? May be a combined cycle approach? How about
an ultra high compression (pressure ratio) turbine that can automatically shift
from a pure turbojet to a turbofan depending upon Mach number and altitude?I would REALLY be impressed if a government and/or private firm can make
a propulsion system without the need to burn something! Now that would be
impressive. Again, what if anything will replace the *conventional* jet engine
in the 21st century is the $64,000 question IMO. The first to do this wins...

Actually Variable bypass turbofans exist. and in form of jet propulsion for the 21st century the PDE is a good canadate. the Scramjet is also another viable engine. And to be completley honest, Nikola Tesla in the early 1900's had plans to incorporate anti-gravity into aircraft with wireless electricity.

Do a quick search on RB545, HOTOL and RR RZ20, the RZ20 was a L2H/LOX hybrid engine.

A lot of work has been done in these areas and is still going on. The problem is that you come down to the basic cost/weight equation with, for instance the inlet stagnation temperature at M=2.2 @ 60K (Concorde cruise point) being about 150 degrees C (300 degrees F) at M=3.0 this stagnation temperature goes up to 500 degrees C (930 degrees F) and at M=4 it doubles to 1,000 degrees C (1832 degrees F). If you could build a commercially viable structure to cruise at these points you would have to have a very effective cooling system to prevent broiling the occupants. As such the heat exchangers to dump the excess heat makes sense.

I just went to a presentation on bio-algae fuels which seems as if it will be coming into common use by 2012. Is this our revenge on the little green men and the brown gunk?

My favorite scheme for going transonic, a plane with 2-3 different engines types.

0 - mach 1.5
Turbo electric in conjunction with turbofan as electric generator. At the moment it's not very efficient and barely prototype work. But the big advantage of electric drive it is a very simple machine and doesn't need complicated high temperature turbine. Imagine a huge electric fan that after reaching around mach 1.5 is folded and retracted into a plane body. It's really just the front end of current turbo fan attached to an electric motor.

mach 1.5 - 2.5
That little turbofan/turbojet that was originally to power the turboelectric fan is fully powering the aircraft.

mach 2.5
air breathing ramjet.

I imagine an airplane of this sort would be similar to concord for turbojet/scramjet, but with addition of turbo electric fan that is folded into the win after reaching mach 1.5. This solve the lousy performance of turbojet at low speed. SR-71 turbojet for eg. was so unefficient at low speed, it has to refuel immediately after take off before doing the actual assignment.

What purpose would a jet this fast serve? Just wondering.

I always wondered if you could take a high bypass turbofan and duct it through a flattened plate of ceramic exhaust. Rather than trying to get rid of that heat use it to superheat progressively until you can reach a sustained chain reaction of converting the exhaust into plasma. As it heats up the exhaust constricts. You inject a fast-expanding fuel (acetylene?) and a small amount of air into that plasma as an afterburner.

Forum: Technology

Hybrid Propulsion System Ideas/Thoughts