Hypersonic drag reduction with forward energy deposition.

If you manage to think up the proper keywords to google, you may come across a substantial engineering subject going back decades.

The idea is a virtual drag reducing aerospike for atmospheric flight at high speeds. (Btw there is a name for a kind of rocket engine design also called 'aerospike', diferent application---at the rear end, not the front end).

An aerospike (classic) is a sharp pointy stick in front of the aircraft which modifies the location and structure of the bow shock in supersonic flow to reduce drag. But there are structural and thermal problems to make this work. I.e. it gets too hot and melts or can't be made strong enough.

By the way, at these high speeds the drag comes from heating and entropy generation, not conventional friction.

But what if you could cause a virtual aerospike with some kind of remote energy deposition, plasma, laser or whatever? Then the hot part is kept away from the aircraft surface. And additionally you could tune the properties based on the phase of flight.

For instance (a numerical simulation):

shock wave mitigation

There are many more going back years. I've noticed many simulations, and few scale, realistic experiments---that's probably classified.

arc.aiaa.org...

aip.scitation.org...

money quote from the abstract:

 The shockwave would sweep the air out in front of the cone, leaving behind a low density column/tube of air, through which the cone (vehicle0 propagated with significantly reduced drag.

If it's done right, a little expenditure of energy mitigates lots of drag.
 
I remember the infamous Astr0 saying something about secret craft that 'make a vacuum' in front of them and are sucked along. Plus some noise about 'ultrasonics', which I think may be intentional misinformation---that is what an insider would need to do, salt truth with invention). It really didn't make sense to me physically in its original form, but now something is coming together.

There's been some developments in high power solid state lasers. For this you'd want something at a wavelength with the highest absorption in air, not the lowest, as is usual. It's very wavelength dependent in IR because of the complex chemical/electromagnetic properties of molecules. And if you have a pulsed laser you can make a plasma which will also deposit more energy.



Add in the MHD engines which can make lots of electrical power (charge a gas, spin it and induce power). 
  
But maybe it's actually ultrasonics and not a laser??

Something using ultrasonics but for conventional (subsonic) drag reduction.

patents.google.com...

Look at year and author institution. B-2A?





a reply to: mbkennel

boundary layer control has been in the forefront of aircraft designers minds for years.

there are many many types of ways to augment this, from using high flux radio isotopes in the skin to ionize the air, to plasmas to ionize the air, to lasers to using positive gas flow.

very interesting find on the B-2A. I wonder if that has anything to do with the bat clean up crews for the F-117, lots of poor poor bats apparently ended their lives running into the aircraft...how do bats fly again, ultrasound. eiter the nighthawk was absorbing the ultrasound or emitting it would be my guess.

a reply to: mbkennel

On aircraft you need drag it allows fighter jets to bank for example. We can eliminate it now almost completely but the aircraft performance suffers. Flip side of that with advanced avionics we could get a brick to fly. The current limit in speed has nothing to do with drag.

The reason we dont make planes to go faster is say are plane was at mach 4 if the pilot attempted to turn he would black out. Faster isnt always better especially in aircraft. We could design a plane that does mach 6 if we wanted to but we restrict fighters to no more then say mach 2.

The reason is there is only 1 advantage to supersonic flight,you get there faster. But when you get there you will drop back down to subsonic You cant fight above mach 1 targetting becomes extremely difficult. And now missiles have got so fast you no longer out run them better to have manuevarability and out turn them. They have the same problem the faster they go the harder it is for them to turn. Id also add no matter what you do above say mach 2.5 you just have to much heat to store in the aircraft meaning your aircraft has to be built out of steele or say titanium and most of that will be heat produced by the engine. At that speed you cant transfer the heat to the atmosphere.

a reply to: dragonridr
The idea is to fly high and fast enough to make interception impossible in the first place. There are not many SAMs that can touch you at Mach 5+ at 100k (or whatever) at any relevant distance.

great thread ... ...

originally posted by: mightmight
a reply to: dragonridr
The idea is to fly high and fast enough to make interception impossible in the first place. There are not many SAMs that can touch you at Mach 5+ at 100k (or whatever) at any relevant distance.

great thread ... ...

We can do that now its not hard but only useful for surveillance. Problem is satellites are cheaper making flying high and fast useless for the expenses it involves. Creating a plane to go mach 6 isnt hard just expensive. And if it can only do one thing fly fast and high what good is it.

a reply to: dragonridr
Its all about mission requirements, not funding. If a three lettered agency decides it needs a time sensitive strategic recon capability it will caught up the couple of billion neccessary to build a suitable asset.

a reply to: dragonridr

But couldn't missiles and drones make use of hypersonic technology? No humans to blackout. And too fast to use conventional anti-aircraft measures to intercept.

Also, wouldn't the proposed virtual aerospike reduce the heating problem?

Regards,

-dex

a reply to: mbkennel

It is still fundamental research afaik. Experiments are done mostly with small blunt bodies in super/hypersonic tunnels using pulsed microwaves or lasers for heating.

For example a 20 mm diameter blunt body (cylinder) showing a wave drag reduction of 20% at mach 5 using a pulsed 150 kHz 750 Watt beam power laser.

From engineering point of view the issues are the high electric power requirements and integration(weight, size).

a reply to: mbkennel

Are we getting into green lady territory?

She supposedly uses an aero spike like that.

You're about 54 years too late! Kelly Johnson figured this out on the SR-71 Design. Glad you're seeking tho, always good to learn new things.

a reply to: mbkennel

originally posted by: dragonridr
a reply to: mbkennel

On aircraft you need drag it allows fighter jets to bank for example. We can eliminate it now almost completely but the aircraft performance suffers. Flip side of that with advanced avionics we could get a brick to fly.

"Flying brick,I like that."
Quote from space cowboys, said by Tommy Lee Jones .
Great movie !

a reply to: dragonridr

We restrict fighters to Mach 2 or so because to go faster requires specialised designs, not all of which are going to be useful in a fighter. Even that Mach 2 speed is only reached under pretty specific conditions.

As for turning and blacking out at high speed, no. The problem with high speed is that the turn radius increases to reduce stress on the airframe. The SR-71 is a great example. Try pulling any kind of G force in that airframe, and it's breaking apart. You can go really fast, or you can be really maneuverable. With a few exceptions fast and maneuverable, at the same time, are mutually exclusive. The faster you go, the wider the turn, unless you want to over G your airframe.

Yes, fighters only go fast to get there sooner, or get away faster, but to be able to do that for any length of time would require a huge airframe. Then you end up in that "I'm an interceptor not a fighter" area.

a reply to: DexterRiley

If you want them to go straight, and really far, yes. You can't maneuver at those speeds without breaking apart any kind of aerodynamic body. You could maneuver slightly, and a hypersonic missile would be scary as hell against larger platforms, like tankers, or B-52s, but they'd have the same problem we had with the Phoenix. Against a small, maneuvering target, they'd have a harder time making kills.

originally posted by: penroc3
a reply to: mbkennel
very interesting find on the B-2A. I wonder if that has anything to do with the bat clean up crews for the F-117, lots of poor poor bats apparently ended their lives running into the aircraft...how do bats fly again, ultrasound. eiter the nighthawk was absorbing the ultrasound or emitting it would be my guess.

Active ultrasonics wouldn't be turned on while in the hangar. Was it the nasty radioactive paint?

originally posted by: Zaphod58
a reply to: DexterRiley

If you want them to go straight, and really far, yes. You can't maneuver at those speeds without breaking apart any kind of aerodynamic body.

Space X lands from suborbital velocities to 5 meter accuracy so something is possible.

a reply to: mbkennel

it was on the runways, but that's what i thought at first as well(the raidopaint). or something in the RAM or the shape that absorbed the ultrasound emissions from the bats. because unless the bats were eating the paint i don't see how Beta emissions would kill at a distance.

that's why i was thinking whatever the mechanism is it has to disrupt the ultrasound of the bats and radiation does not do that(as far as i know)


im sure the reason is known, but not by me. might give something away?

a reply to: penroc3

No, it was in the hangars. The bats were found around the tails mostly.

a reply to: Zaphod58

hmm, i still wonder what its about.

a reply to: penroc3

The materials in the aircraft absorbed their sonar, so they saw an open space in front of them and flew into them.

It´s good to see this topic here again. This technology is evolving fast, coupled with the necessary electric power needed.