Hermeus hypersonic aircraft project

TomcatViP said:
Is that all stainless steel? I don't see any primer or paint.
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Might well be. They talk here about using mostly Inconel 718 and titanium. It's a little vague on when they are talking about the airframe and when they are talking about the engine, but either way, lots of corrosion-resistant materials in use.

www.assemblymag.com

Hypersonic Aircraft Push the Boundaries of 3D Printing

The aerospace industry recently celebrated the 75th anniversary of supersonic flight. Chuck Yeager broke the sound barrier on Oct. 14, 1947, aboard the Bell X-1 rocket plane.
www.assemblymag.com www.assemblymag.com
 
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Grandiose announcements and a millimetric pace forward (now a prototype for high speed rolling & praying!).

Quarterhorse Mk 1 is an uncrewed, remotely piloted aircraft powered by a GE J85 engine. Its primary mission is to demonstrate high-speed takeoff and landing – a key enabling capability unique to future hypersonic aircraft on the company’s roadmap. Flight tests will take place at Edwards Air Force Base.
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I wasn't aware that a Quarterhorse was in fact a millipede...

licensed-image

Quarterhorse galloping


Notice also that the Mk2, as rendered, has some dubious stability characteristics.
 
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TomcatViP said:
Grandiose announcements and a millimetric pace forward (now a prototype for high speed rolling & praying!).



I wasn't aware that a Quarterhorse was in fact a millipede...

licensed-image

Quarterhorse galloping


Notice also that the Mk2, as rendered, has some dubious stability characteristics.
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Maybe they fail. I’m still interested in the technology - or rather reinventing an old arrangement. I think the fact the turbine-ramjet has not been explored more is a mistake, even if it turns out this particular company is a pump and dump.
 
Alex Hollings from Sandboxx has just put out a new video concerning the Hermeus:


Atlanta-based Hermeus has been making rapid progress toward fielding the world's first reusable, air-breathing hypersonic aircraft in their Quarterhorse technology demonstrator. Last month, the company revealed Quarterhorse Mk 1, the company's first flying prototype.
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Let's talk about what that means, and why it's hard not to draw parallels between Hermeus today, and another legendary aircraft manufacturer.
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New video, that interestingly show the cluster f*** that is their facility where engineer might have the concentration time to focus on a single problem as short as a quantum physics event.
Notice also that there is no natural lights, something that is often against local regulations for stationary work stations.

You´ll notice also the strange protruding bolt heads, the thick wing and elevator section (I don´t say airfoil as it doesn´t look like they are shaped according to any), not really built for any speed above that of a Cessna with, for the former, a weird intrados opening on a void depleted of any stringers to brace it.

But , oh yes, the references to aerospace History and other´s achievements are plentiful.

Feel free to commit yourself into it.

View: https://youtu.be/jdKUN2V0PMM?si=LMgrGW2YJzqtbzIJ
 
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As a former recovering hypersonics cult member, I call aerothermodynamically heated BS.
 
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Hypersonics and scramjets are a waste of time, except perhaps for super duper missiles. Why not just go ballistic / suborbital instead, on plain old rocket power ? and out of the atmosphere, so much less thermal nightmare.

I will die on that hill: for point-to-point ultrafast transportation, hypersonics (= LAPCAT) has a big, unsolved sonic boom issue... that don't exist for suborbital. Except perhaps briefly during ascent and landing.

Plus it is far easier to hit any speed between Mach 4 and Mach 25 (= orbit) with rocket thrust.
 
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Archibald said:
Hypersonics and scramjets are a waste of time, except perhaps for super duper missiles. Why not just go ballistic / suborbital instead, on plain old rocket power ? and out of the atmosphere, so much less thermal nightmare.

I will die on that hill: for point-to-point ultrafast transportation, hypersonics (= LAPCAT) has a big, unsolved sonic boom issue... that don't exist for suborbital. Except perhaps briefly during ascent and landing.

Plus it is far easier to hit any speed between Mach 4 and Mach 25 (= orbit) with rocket thrust.
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Fully reusable CTOL spaceplanes dropping out conventional, guided MaRVs in large numbers are where it's at.
 
Archibald said:
Hypersonics and scramjets are a waste of time, except perhaps for super duper missiles. Why not just go ballistic / suborbital instead, on plain old rocket power ? and out of the atmosphere, so much less thermal nightmare.
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Not sure why you feel scramjets are a waste, unless you think they will be too costly? I think the USAF intends to buy HACM quite prolifically. And I do not see a reason why something like HACM could not be produced for reasonable cost. The airframe does not really require any special materials outside of the nose tip (X-51 was basically aluminum, steel, and titanium with some space shuttle tiles on the nose). The solid rocket booster only has to be something in the size and power class of a Mk72-ish. The engine is entirely 3D printed with no moving parts. I do not see why this could not be a ~ $5 million dollar mass produced missile not to far off from SM-6 or LRASM in price. Furthermore, the relatively lower speed compared to boost gliders and RVs should make the use of a terminal radar homing sensor relatively easy to engineer. There are already radomes that have to survive Mach 5 for short periods of times; this would just extend that requirement out to five minutes instead of just seconds. Alternatively ventral mounting on the compression ramp would probably take the worst of the heat stress off the sensor window, since the tip basically acts as an aerospike for the airframe. Alternatively the sensor could just have a cover that released as weapon slowed for its dive onto the target.

It seems to me there would be a very large target set for such a missile.
 
Josh_TN said:
Not sure why you feel scramjets are a waste, unless you think they will be too costly? I think the USAF intends to buy HACM quite prolifically. And I do not see a reason why something like HACM could not be produced for reasonable cost. The airframe does not really require any special materials outside of the nose tip (X-51 was basically aluminum, steel, and titanium with some space shuttle tiles on the nose). The solid rocket booster only has to be something in the size and power class of a Mk72-ish. The engine is entirely 3D printed with no moving parts. I do not see why this could not be a ~ $5 million dollar mass produced missile not to far off from SM-6 or LRASM in price. Furthermore, the relatively lower speed compared to boost gliders and RVs should make the use of a terminal radar homing sensor relatively easy to engineer. There are already radomes that have to survive Mach 5 for short periods of times; this would just extend that requirement out to five minutes instead of just seconds. Alternatively ventral mounting on the compression ramp would probably take the worst of the heat stress off the sensor window, since the tip basically acts as an aerospike for the airframe. Alternatively the sensor could just have a cover that released as weapon slowed for its dive onto the target.

It seems to me there would be a very large target set for such a missile.
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This is the super duper missile I mentioned.
 
The F100 engine probaly is also getting a precooler which is a very smart thing. If i understand it right then they don't need a scramjet at all for Low hypersonic speed mach 5-6 as the slowed down Air should be as easy to handle for the ramjet as something around mach 4-4.5.
View: https://youtu.be/cYA21g10b1c?si=dEUiqwJ4-KovI9c9
 
Scramjet is for velocities above Mach 6 (supersonic combustion). Below that, its ramjets (subsonic combustion is working). If their target is Mach 5, MIPCC on a F100 can certainly do it. Research done 30 to 25 years ago showed Mach 4.5 was feasible.
 
NMaude said:
Using a pre-cooler based on the pre-cooler used in the SABRE?
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A pre-cooler would be very useful to increase the performance of any turbofan (F100-229 included) in the M2+ environment with high inlet temperatures. However, what heat sink are they planning on using? Liquid H2 makes a great pre-cooler heat sink and subsequently as a fuel for the engine, but I have not heard any indication that Hermeus is planning to use hydrogen.
 
Why Lockheed Martin or Boeing don't use the technology of the pre cooler on their fighters ?
 
Archibald said:
Scramjet is for velocities above Mach 6 (supersonic combustion). Below that, its ramjets (subsonic combustion is working). If their target is Mach 5, MIPCC on a F100 can certainly do it. Research done 30 to 25 years ago showed Mach 4.5 was feasible.
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With this is 100% possible at those speeds and maybe even more efficient/good for the engine
 
dark sidius said:
Why Lockheed Martin or Boeing don't use the technology of the pre cooler on their fighters ?
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Because its relativ new, heavy, makes the engine larger, more complex engine and is Not needed as afterburner are more than enough for mach speed around 2.
 
The other pre-cooler concept that I have read about involved injecting liquid O2 into the inlet stream where the vaporization cooling would offset the high ram temperatures, plus would be available for downstream combustion with traditional kerosene type fuels (RASCAL ?) LOX storage is easier and less bulky than LH2, you don’t need an inlet heat exchanger (cost, weight, inlet pressure loss), and it might be only needed for a short time during acceleration from M2 to ram jet transition. Just as long as the O2 concentration and pressures stay below the Titanium ignition parameters in the F100-229 fan and front end of the high compressor.
 
You can use helium in the pre-cooler heat exchanger and then use the heated helium to drive the turbine, while the combustion products are expanded out the nozzle.
 
That is basically the P&W 304 Suntan engine, except the heat exchanger was in the exhaust flow, using LH2 expanding to gaseous H2 driving a turbine that powered the engine fan, then burning the H2 both before the heat exchanger and in an afterburner aft of the heat exchanger. This was intended for high altitude M2.5 operation. Helium vaporization could drive a turbine, but it would be a total loss system with the helium unable to provide any additional combustion power.

But it doesn’t address any precooler for Hermeus plan for afterburning turbofan transitioning to ramjet cycle for speeds approaching M5.
 
F119Doctor said:
That is basically the P&W 304 Suntan engine, except the heat exchanger was in the exhaust flow, using LH2 expanding to gaseous H2 driving a turbine that powered the engine fan, then burning the H2 both before the heat exchanger and in an afterburner aft of the heat exchanger. This was intended for high altitude M2.5 operation. Helium vaporization could drive a turbine, but it would be a total loss system with the helium unable to provide any additional combustion power.

But it doesn’t address any precooler for Hermeus plan for afterburning turbofan transitioning to ramjet cycle for speeds approaching M5.
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The helium doesn't provide combustion power, the air comes in the pre-cooled intake, passes through the compressor and then into the combustion chamber before expanding out the nozzle, while the helium heated in the pre-cooler drives the turbine to drive the compressor. SABRE uses this technique to apparently reach M5.5 in theory.
 
Forest Green said:
The helium doesn't provide combustion power, the air comes in the pre-cooled intake, passes through the compressor and then into the combustion chamber before expanding out the nozzle, while the helium heated in the pre-cooler drives the turbine to drive the compressor. SABRE uses this technique to apparently reach M5.5 in theory.
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I’m not saying that cycle won’t work, it is just that the helium cooling and turbine expansion seems to be low energy solution with the helium being discarded after expansion vs using hydrogen which can be burned. Unless SABRE has some way to recycle the helium back to liquid form, but that take power out of the system (is the turbine expansion only to run a helium compressor?) and you have to shed the helium compression heat somewhere else.
 
F119Doctor said:
I’m not saying that cycle won’t work, it is just that the helium cooling and turbine expansion seems to be low energy solution with the helium being discarded after expansion vs using hydrogen which can be burned. Unless SABRE has some way to recycle the helium back to liquid form, but that take power out of the system (is the turbine expansion only to run a helium compressor?) and you have to shed the helium compression heat somewhere else.
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The helium is recirculated back to the pre-cooler after expansion, the turbine it was expanded through drives an air compressor. After the compressed air goes through the compressor it enters the combustion chamber, where it is mixed with fuel, it is then expanded via the nozzle to provide propulsion... roughly... it's slightly more complicated overall. The LH2 pump heat-exchanger cools the expanded He further before it goes back to the pre-cooler, after heating in the pre-cooler the He is further heated by the pre-burnt H2 mix before going back to the He turbine. Picture below is worth a million words.

www.gov.uk

Synergetic Air-Breathing Rocket Engine (SABRE) Programme Evaluation Report 2022

www.gov.uk www.gov.uk
1716231889840.png
 
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@F119Doctor In the SABRE concept(s) the helium is in a closed loop. It works due to also having the large volume resevoir of LH2 to reject the heat into. Effectively its somewhat allowing you to decouple precooler flow rate and fuel flow rate. Whereas if you use LH2 for both then the fuel consumption rate is very high.
 
Thanks for the schematic, now I understand. Basically using the helium as the working fluid for a heat pump system moving heat from the inlet to the LH2 fuel, which is the ultimate heat sink with the waste heat going out the exhaust. I still don’t really see how this decouples the system from the LH2 fuel flow, since a lower LH2 flow rate means less heat rejection, raising the inlet temperature, etc.

The other issue I see is using the same nozzle for the rocket combustion chamber and the air breathing combustor. Rockets chamber pressure tends to be way higher than an air breathing combustor, even with the ram recovery and air compression system. Using both is likely to have the rocket exhaust very under expanded (inefficient) to prevent operating the air breathing system with an over expanded nozzle condition (separated unstable flow, poor efficiency)

Hopefully the SABRE group knows more than I do!
 
Sabre uses the He loop because too much hydrogen was diffusing through the heat exchanger tube walls. With H2 massive flammability range it was considered a fire/explosion risk downstream with the elevated T and P.

I remember once being told that LACE had suffered likewise in its brief operation and was one of the “to be solved” problems at cancellation. Also LACE’s individual engine were all very short due to the icing and that had saved it from going bang.
 

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