Longshot multistage gun launch

[Asteroza]

So there's these guys

https://www.longshotspace.com/

Who seem to think instead of a multistage gun launcher using multiple stages to push on the rear of a projectile directly (like the classic V-3 gun from WWII), they can use a longer tail on the projectile and push more from the sides to "squeeze" it forward using compressed air injector stages.

[edzieba]

They're not a multi-stage gun because they are eschewing combustion entirely. The scheme is trying to sidestep the speed-of-sound limit of the light-gas gun, by not using pressure to push the projectile. Instead, the projectile is a reversed wedge and you impinge jets onto the sides of that wedge, so good old reaction forces and the wedge angle determine the resultant maximum speed. e.g. if you have Mach 1 air jets impinging on a wedge with a 4:1 incline, then as long as you have a long accelerator it should be able to reach Mach 4. Depending on pressure within the launch tube and available compressed air tank pressure you might be able to pull some extra tricks by using de Laval nozzles for the injection, particularly as the area behind the projectile does not need to remain pressurised so can be vented down as the projectile passes - the tube ahead of the projectile needs to be evacuated to cut air resistance losses and the tube itself is useful as a projectile guide, but in a vacuum environment the tube could be eliminated and the nozzles placed in free space along with some suitable mechanism or control system for keeping the projectile guided through them during acceleration.

[Magnum]

Howdy

Some of this brings Dr. Gerald Bull's work to mind.   Bull spent some time & effort trying to come up with a cannon design that could launch small satellites into space economically.

His work on " Extended Range Full Bore " projectiles included things like aerodynamic shaping, " base bleed " projectiles, smaller leading " guide nibs "; lower drag driving band treatments; and more.  One of his guns fired a projectile that set an altitude record that still stands.

Amongst his last efforts was work he put into the Iraqi  " Project Babylon " PC-2 gun,  emplaced on the side of a mountain.


With regards,
                       357Mag

[stefan r]

They're not a multi-stage gun because they are eschewing combustion entirely. ...

In the demonstrator they built they used compressed air.  I suspect for a launch at orbital velocity they will use rocket propellants. 

[edzieba]

They're not a multi-stage gun because they are eschewing combustion entirely. ...

In the demonstrator they built they used compressed air.  I suspect for a launch at orbital velocity they will use rocket propellants.

Sure, but that's not the key difference: they're using jet impingement rather than gas pressure, the source of the gas jet is not the important part. You could use combustion products, though that has some issues that a cold gas get avoids (fouling, gas temperature control, combustion product molecular mass control, etc).
You could go for a hydrolox combustor-generator, but then you need to deal with a hot mix of steam and hot H2 & O2 (nasty!), along with having flammable pressurised gases (or cryogens) on hand, and dealing with all that exhaust water condensing in your system. Replace that with an inert gas jet and things get quite a bit simpler. Since all your infrastructure is stationary, the mass efficiency of a combustion system is moot.

[StraumliBlight]

Longshot's test gun hit Mach 3.6 recently and they eventually want to scale up to a 24 km evacuated tube with a 9 km/s exit velocity.

There's a public hearing tomorrow to develop a hypersonic test facility at Tonopah Airport by March 2027.

[catdlr]

Longshot Space Introduction Video and Teaser Video

[StraumliBlight]

Longshot Space closes over $5M in new funding to build space gun in the desert [Sep 25]

The company raised a $1.5 million pre-seed round in April 2023; now, nearly 18 months later, Longshot closed a little over $5 million in combined venture funding and non-dilutive funding from the U.S. Air Force’s TACFI program. The new capital will be used to build a massive, 500-meter-long gun in the Nevada desert to push 100 kilogram payloads to Mach 5.

The move to Nevada is needed; Longshot has built out a prototype from its facilities in Oakland, California, but a dense, urban location is not the best place to site increasingly large space guns. The Oakland prototype hit 4.6 Mach speeds, but going any faster will mean a longer tube and the use of highly combustible hydrogen gas.

https://twitter.com/LongshotSpace/status/1838316949920715008

https://twitter.com/LongshotSpace/status/1838316954211475827

https://twitter.com/LongshotSpace/status/1838316958938435616

[Vultur]

Can they build a 500 meter gun anywhere near that cheaply???

[edzieba]

Can they build a 500 meter gun anywhere near that cheaply???

If they were building a Bull-type supergun, then probably not.
But what they have is closer to a pulsed ram-accelerator in that the barrel does not need to hold internal pressure to push the projectile (projectile is accelerated by jet impingement). The barrel needs to have some internal bearing elements that are machined to be straight and parallel in order to guide the projectile, but they do not strictly need a 500m long machined circular bore or a 500m long high pressure vessel.

[gaballard]

The world is already full of entrepreneurs trying to get investor money for every kind of novel launch method ever conceived. This is so pointless. Vertical-take off rockets work. Jules Verne thought of pointing a giant cannon at space in the late 1800s. There’s a reason it’s 2024 and no one has done it.

These guys seem to be resting on their resumes to get money from gullible VCs who have FOMO about not getting in the door with “New Space”…

My pain point is this: can people stop trying to re-solve launch and actually build the “things” these guys want to get into space?

Launch is solved. The problem we’re seeing is a lack of economic reasons to do anything in space beyond earth observation satellites and comms. Can someone please, please work on that?

Instead of re-inventing the wheel with this novel wheel design someone thought of almost a century and a half ago and no one has built because it’s not as good as a regular wheel…

(Edit: “Long Shot” is at least an appropriate name for a business with a slim chance of succeeding)

[Robotbeat]

...
My pain point is this: can people stop trying to re-solve launch and actually build the “things” these guys want to get into space?

I agree. But people seem to want to dunk on just about any new thing people want to launch, too.

[deltaV]

Cool tech but what is the market? In addition to the usual small launcher woes they need payloads that can tolerate ~500 gees. Propellant is a possibility but Starship will be a formidable competitor.

[Cheapchips]

S3 interviewed the team this weekend.

[StraumliBlight]

S3 interviewed the team this weekend.

At 13:00, they mention building a 15 km long gun with a Mach 25 exit velocity that can fire a 2 m diameter projectile, weighing 3000 kg, with a 500 kg payload into orbit.

Aiming for launch in 2028-2029 in Northern Australia, as its relatively unpopulated and the gun will be really loud.

[catdlr]

S3 interviewed the team this weekend.

At 13:00, they mention building a 15 km long gun with a Mach 25 exit velocity that can fire a 2 m diameter projectile, weighing 3000 kg, with a 500 kg payload into orbit.

Aiming for launch in 2028-2029 in Northern Australia, as its relatively unpopulated and the gun will be really loud.

At a 15 Km barrel, it will be interesting to see how much energy is expended just pushing out the air in that tube ahead of the projectile or the mechanic to perhaps keep the barrel in a vacuum before it fires.

[deltaV]

At 13:00, they mention building a 15 km long gun with a Mach 25 exit velocity that can fire a 2 m diameter projectile, weighing 3000 kg, with a 500 kg payload into orbit.

Aiming for launch in 2028-2029 in Northern Australia, as its relatively unpopulated and the gun will be really loud.

They also mention they'll use cold gas thrusters once at orbital altitude to get the last bit into orbit.

They later mention they'd do a bigger gun with 40,000 kg payload if they had more money.

[FutureSpaceTourist]

[Cheapchips]

I don't know if I missed it in prior interviews, but I was wondering how they were going to replace burst disks on the full sized gun.  In the Manley interview, they mention that they have a prototype of a 'hydraulic clamp ram thing' to do disk replacement.

Not recycling 100 tons of hydrogen seems expensive. In the timeline they're planning, there some chance that cheap solar powered electrolyzers could deliver that at $1kg.  Their planned location of Australia is obviously a good spot to be running those adjacent solar hydrogen plants.

[StraumliBlight]

Longshot have started construction at Tonopah. [Nov 8]

Delivery Day is here, and we’re thrilled to bring this custom unit to Longshot Space Technologies Corporation in Tonopah, Nevada. This project is more than just a build; it’s a collaboration to pioneer affordable, innovative solutions for Earth and beyond. 🌍🚀

This delivery marks another milestone in our mission to redefine what’s possible in sustainable, compact living. The work we’re doing with Long Shot Space not only aligns with our vision but opens up new avenues for the future of affordable housing.

My Tiny Home Hub blog

Tonopah, located in the Nevada desert, presents extreme temperature swings between scorching hot days and chilly desert nights—conditions that demand durable, insulated, and adaptable spaces. Longshot Space will be using our 800 sq. ft. expandable container home to provide their team with a comfortable work environment during long testing days. With built-in climate control and durable materials, the container home offers respite from the heat while providing ample space for meetings, equipment storage, and rest.