Comments on: SpinLaunch gets first launch contract, from Defense Department

By: wayne

wayne — Tue, 25 Jun 2019 16:26:27 +0000

A longer article—
“The High Altitude Research Project (HARP) space gun was set up at Paragon just to the east of the runway of what was then Seawell Airport – the brainchild of Canadian ballistics scientist Dr. Gerald Bull and jointly funded by McGill University, Canada and the USA Army Research and Development Center”
https://www.bajanthings.com/high-altitude-research-project-harp-1962-1967/

(tangentially– why do I always have the feeling, that we always have to pay for research, at least 3X’s over with these “people.”)

(Again, there is a Sky & Telescope article from that period, that is a bit more technical & comprehensive.)

By: wayne

wayne — Tue, 25 Jun 2019 16:19:45 +0000

Ryan–
You need to check out Project HARP (not to be confused with project HAARP) in Barbados, 1962-1967-ish.
“Designed by ballistics engineer Gerald Bull, the gun itself was originally built from a 65-foot long, 16” naval cannon, the kind that might be seen on a battleship. The cannon was later joined to another barrel, extending the length of the gun to 130 feet and making it too big for effective military application, but (seemingly) perfect for satellite delivery. The titanic gun was not designed for delivering human subjects, but instead, the cannon fired smaller projectiles in a sabot that would protect the payload during the firing and would fall away as the satellite rose. At its apex, the gun was able to fire an object a staggering 112 miles into the sky, setting the 1963 world record for gun-launched altitude at 93 KM.”

There is a particularly comprehensive article in Sky & Telescope from that period that lists the payloads launched, but I don’t have a date or a link handy for you.
For maximum altitude, they did employ a system that evacuated the air from the barrel prior to firing.

very brief description is at:
https://www.atlasobscura.com/places/project-harp-space-gun-barbados

By: Ryan Lawson

Ryan Lawson — Tue, 25 Jun 2019 14:47:39 +0000

Edward,

It seems to me an advantage of the cannon system he was working on was that it was mostly just a series of giant pipe sections you could produce fairly cheaply. This would enable extending the length of the whole system to a point that you reduce the extremes of your acceleration bursts on the launch vehicle. It should even be possible to partially evacuate the air in the barrel and through other techniques, create a zone around the muzzle to reduce the stresses of transition into normal air pressure. But, this may all be obsolete now with what SpaceX is doing.

By: Edward

Edward — Tue, 25 Jun 2019 00:21:26 +0000

Ryan Lawson,
My thinking is that if a rocket can tolerate the side-load forces of a centrifuge, then we could build a cannon that has a similar axial G-load. By my calculation, a 100 meter arm would rotate at a rate of 17 radians per second, creating a side-load force of 3,000 G (30,000 m/s^2). A 3,000 G cannon would need to be 100 meters long to accelerate the rocket to mach 5.

If I decide to go this route, I’ll be sure to learn from Bull’s mistakes and do it commercially to avoid the governmental assassins.

By: Ryan Lawson

Ryan Lawson — Mon, 24 Jun 2019 22:02:05 +0000

Edward, I always wondered why no one attempted a heavily modified version of the “super gun” Gerald Bull was working on. There has to be an appropriately positioned and angled mountain somewhere along the equator to fit it to.

By: Edward

Edward — Fri, 21 Jun 2019 23:18:32 +0000

Unlike the earlier article, this article contains some interesting information.

A chemical rocket is to be flung from a centrifuge, travelling at mach 5 or so, sort of like the largest sling ever. The rocket then ignites to carry the payload to orbit.

My suspicion is that the Department of Defense is interested in how well this works. As with air-lifted rockets (e.g. Pegasus and LauncherOne), the rocket can be smaller due to the head start provided by the “reimagined” launch system.

I am having trouble imagining a realistic arm length for the centrifuge and a corresponding spin rate that gives a mach 5 (1,700 m/s) speed for the rocket. A 100 meter arm (200 meter diameter centrifuge) would need to spin at almost three revolutions per second.

No matter the design, the outer 4/5ths of the arm would be travelling above mach 1, generating a nice shock wave.

If this Spinlaunch concept works, I will have to consider getting into the small launcher business using a cannon with a long barrel to reduce the overall acceleration rate. It seems more practical, to me.

By: Gealon

Gealon — Fri, 21 Jun 2019 14:47:31 +0000

I continue to remain highly doubtful of this. At least that toy rover I commented on a few months ago had some actual hardware. So far all we have from these people are “Secrets” and a computer graphic which seems to confirm the suspicions I raised the last time I commented on Spin Launch. But the government will throw money at just about any scheme it seems. Until they can show measurable results and at the very least, how they intend to actually get the payload into orbit with any semblance of accuracy, I am of the mind that this is just a scam. But hey, if the DOD wants to pay to spin payloads around and hope something horrible doesn’t happen, I have a bridge they might be interested in buying.