SR-72 Confirmed: Mach 6 Project Blackswift

a reply to: Blackfinger

The tiles like the nose cap and leading edges were carbon-carbon. They were coated with a complicated ceramic process to help protect from ionization, and needed to be replaced and refurbished after a dozen or so flights. Those flights spent a small amount of time plowing through the atmosphere at hypersonic speeds, and the leading edges were dull for the reasons given above. They were duller than ideal for a hypersonic cruiser because they didn't mind increased drag, and wanted to mitigate stagnation point heating. X-37B uses slightly fancier tiles built on the same principles, and heat blankets like the Shuttle.
The other tiles, are not going to be enough protection (they are pretty neat though)

Our hypothetical cruiser cannot be that dull, and it will spend more time plowing through the air at hypersonic speed. We will need a better/larger/thicker/heavier (pick one or three) thermal protection system than the shuttle.

a reply to: RadioRobert

im sure with a supercomputer, cryogenics, plasma theory degree, and replaceable leading edge/nose like the shuttle we could figure it out.

a reply to: Masisoar
ROFLAO!!!!! But if it works does it count as being a bad idea?

originally posted by: penroc3
a reply to: RadioRobert

im sure with a supercomputer, cryogenics, plasma theory degree, and replaceable leading edge/nose like the shuttle we could figure it out.

There has certainly been a lot of time and money spent by people trying to figure it out, yes.

a reply to: RadioRobert

one or both of thye fuel mixtures(to get up to speed) are cryogenic the X-15 used liquid Ammonia as it was really cold and was right where the fuel tank would be

ANYWAY

just use what ever cryogenic liquids you are using to run the first stage and save enough to circle around the skin before being used in some way after absorbing the heat aka active cooling heck you could do it with JP-5 going to a preceooler and you could even used the ship and its a advanced thermocouple at various actively cooled areas and a way to cool with heat


a really cool way would be a way to turn heat energy into liqgt energy

a reply to: penroc3

So I "just" need to heat my cryogenic fuel? How do I cool the excess fuel I am carrying now that I heated it? Or do I just keep letting it heat? What happens to a liquid when it is superheated? To have an effective radiator, I need to transfer the heat somewhere. Where is the heat going? I can bleed the heated fuel out to an engine or just into the air behind me, but how long will that fuel last in that scenario?


What benefit is there to carrying excess fuel and a lot of plumbing and pumps(which I hope are extremely reliable) over other methods of thermal protection?


Heat energy will definitely be turning into light energy at these temps, but not in the quantities necessary to overcome the nontrivial matter of thermal protection.

Shuttle flights spent about 30 minutes on reentry going through hypersonic flow. They required inspection and repair to RCC tiles and nosecap after every flight. Damage and repair was frequent. The tiles suffer from damage from ionization and ablation every flight. Repair was frequent. The nose cap needs complete refurbishment after less than 20 flights. Frequently sooner if ablation was deep enough.

Now our hypothetical hypersonic cruiser will be spending longer than thirty minutes at hypersonic speed exposed to superheated and ionized air. Our sortie to repair/refurbishment/replacement ratio even using RCC is going to look very, very bad.

The goal here is not just to do it, but to make an operational aircraft and (whatever it is we decide) capability. That means cost and reliability is not a tertiary concern. If the Germans could have build a B-52 in the 40's, it wouldn't have meant much if the investment of materials, manhours, and reichsmarks bankrupted the Luftwaffe to build one and fly it once every three months.


I'm not trying to mock you, there are semi -serious professionals pursuing similar ideas. I don't think you'll find the answer is going to be "just" anything. And I'm fairly confident that the first answer is going to be cryogenic fuels, though if it was the main fuel, it would conceivably help transfer heat from say, the wing to the exhaust. But that introduces some nontrivial problems as well. If we "just" needed cryogenic fuels to make a viable hypersonic aircraft, we would have done it in the 60's when the idea arose.

I wonder if anything good has come out of CERN?

a reply to: Blackfinger

Why CERN?

a reply to: RadioRobert

i was talking about a clearly non existent and overly complicated ideas to point out the absurdity of it all.



so how would you dump heat in such a platform

a reply to: penroc3

I would rely on thick, heavy, ever (slowly) improving heat blankets. Which is why we don't have one.

And to be clear, I think we have gone quite a bit faster than recorded. I'm even willing to very shakily believe we had an operational hypersonic platform in the 90's. I have even discussed my belief that such a platform could be survivable even in a modern IADS environment. If we're not doing it today, it's because of cost vs utility.

Let's say our cruiser has a heat capacity that allows for a twenty minute sprint. Or enough fuel for 20 minutes. Mach six at 100,000, is about 4000 mph. That's 1333 miles. Or about 667 miles in, and 667 miles out. Now overlay that on the Pacific, and ...

Couple that with scramjets really not liking non-uniform flow, like I think anza posted earlier. We maneuver and now shockwaves have different geometry going down the throat of our engine, and we're way outside of the engines happy -place. If we maneuver and our engine thrust is now unpredictable, we've got some problems. Maneuvering also breaks up boundary layer flow and makes it choppy. This is bad. Not only do I now have more drag and heating, it's really hard to predict where exactly that heating is taking place! Not a big deal at Mach one, but here at Mach 6 where dynamic pressures are 25 times greater, this is a big problem. What happens if my control surfaces create shockwaves that impinge on the structure of the fuselage or tail? Etc, etc

If I cannot maneuver at speed, I am even more limited operationally. I can go fast, but not very long, and I cannot maneuver. Not looking good for survivability and usefulness.

Then we've got RCC leading edges at $100,000 a square foot needing constant replacement, other exotic materials, expensive fuel, perhaps increased by unique fuel storage demands, perhaps a dedicated tanker or two, regular maintenance demands, etc, etc. If it costs me tens or hundreds of millions per sortie for the program, and the sortie is of operationally limited usefulness, then there's not much call for having it.

I don't think going very fast is impossible. I think we've mostly had the technology from the 70's onward to go very fast. It's turning that technology into something that goes fast enough, long enough, and at a cost that makes sense for the utility that is going to continue to be the hard bit.

A bit like going to the moon. We could start a plan to go back to the moon, or even head to Mars, tomorrow. The technology exists and has for decades. What hasn't caught up is the math on dollars/utility. How much does it cost to get to Mars, and what can I do when I get there? Technology hasn't caught up to the cost-benefit curves.

I think LockMart (even Boeing with their inherited MDD work) could build a hypersonic aircraft starting tomorrow. Zero (or nearly so) problems. What hasn't been shown is that we can make one that is not incredibly expensive or which would be of great use to us.

a reply to: anzha
They seem to be one of the front runners in covering new ways on how particles and energy react.Plus been doing it for a fair few years.This seems familiar..
ALICE

a reply to: RadioRobert

There was a way around that though, just fly higher.

originally posted by: Masisoar
a reply to: RadioRobert

There was a way around that though, just fly higher.

Common misconception. Max/equilibrium temperatures are identical for Mach numbers regardless of altitude. The only thing that altitude changes is the rate of heat gain (btu/time).

And getting up above 120,000 feet or so, makes it much, much more difficult to sustain an airbreathing engine. That means carrying around an oxidizer, which is then competing with thermal protection, fuel, mission payload for space and weight.

Theoretically, you can get a scramjet up to 200,000 feet or so, but scramjets are still Newtonian. We have to kick mass out the back for thrust. Usually in a jet engine that's mostly air, a little bit of fuel, sometimes an additive, ie water injection. If I don't have sufficient air mass, like I would not way up high above 120,000 feet or so, then I need to kick more fuel out the back for a given amount of thrust. For a short duration flight like a scramjet booster stage, to orbit or otherwise, that's not such a big deal. For a "cruiser" that's a big, big problem.

a reply to: RadioRobert

if you got above the karmin line and had RCS like thrusters and maybe even fuel for an orbital insertion and then enter back in like the shuttle but with a powered landing.

once you were in zero G and out side the atmosphere for the most part you can pick up alot of speed per heat unit.

what if the green lady sightings were something coming back and not going out.

a reply to: penroc3

ive always wondered if you could look up who gets space wings in the USAF or any other service. imagine being a legit astonaught and not being able to tell ANYONE.

kind of like the MOL guys

a reply to: penroc3

Then now you need to build a space plane with all that entails which "only" needs to have an engine that doesn't rely on air, has enough fuel/thrust/delta v get to 17,448 mph instead of 4,000 mph, and still needs TPS to protect itself on reentry. Suborbital ballistic space flights would be easier, but nations tend to get queasy when a large spacecraft is launched their direction. Particularly on a ballistic path, and it's still harder, more expensive, heavier than our "cruiser".

And our new SSTO platform doesn't offer much advantage over a rapidly deployed satellite.

Have to think of what "cargo" they are carrying as well..Think the SSTO platform has more flexibility in regard to be at a certain spot at any time of day where a Sat has an established orbit that comes over at regular times..

a reply to: Blackfinger

So what advantage would a reconnaissance SSTO offer over a rapidly deployed satellite or constellation of satellites? Not cost. One sneak pass? Same with a Pegasus launch, plus it gets more passes. Or I can put four big sats up high and get global coverage 24/7. Only advantages to a SSTO is proximity/sensitivity of sensors and lag. I can put a dozen of Starlink-style sats up and have 24/7 coverage over a given point in LEO. I can launch them five dozen at a time. And I get them just as close to the target as an SSTO platform at considerably less cost. Using a system of composite arrays, a SSTO doesn't even get a size advantage for sensors. I'm struggling to see a military mission for SSTO designs these days.

I'm struggling to see a military mission for SSTO designs these days.

Unless you can parachute from a Sat a SSTO can get someone or an object from point "A" to point "B" in rather a hurry.

China and Russia both know to the exact second when our sats will be overhead


with things going the way they have been with China something you can fly over them at any moment is pretty huge.