Posted on 06/14/2018 12:24:13 PM PDT by C19fan
“Did they mean RAP (Rocket Assisted Projectile) round? I don’t think a RAM-jet is feasible for artillery.”
Hybrid systems - part rocket, part ramjet - have been in routine use for decades in guided missile systems. Auxiliary pure rockets boost the missile airframe to an airspeed high enough to keep the ramjet operating; then it takes over and powers the missile airframe the rest of the way to the target.
The advantages of a ramjet over a gas-turbine jet are simplicity, cost, and weight; the disadvantages are that a fairly constant speed must be maintained; so a ramjet cannot operate in as many different flight regimes as a turbojet.
One advantage of a ramjet over a pure rocket is smaller size/weight for a given payload, speed, and range; the ramjet uses external air and does not need to tote its own oxidizer. One disadvantage: external air supply is crucial. Rockets do tote their own oxidizer and don’t need air to operate.
A question not brought up in the article: can a ramjet be fitted into a projectile small enough to be fired from a gun barrel? Turbojets are made small enough these days, to fit into radio-controlled model aircraft; perhaps ramjets can be downsized the same way.
SJSAMPLE is quite right to be concerned about feasibility.
As I recall, some in the U.S. intellegence agencies attempted to put him out of business.
Without the U.S or allies willing to work with him (blackballed), he turned to other customers.
Its greatest advantage? It has no conscience.
;^)
His brilliance was used to the full. There is not and never was any competition with NASA, although the research was carried out by the DoD. It was found to be infeasible.
Bull wanted to build his supergun, and Saddam Hussein was willing to pay for it. Iraq had already been a customer for his howitzer enhancements which approximately doubled their range. During the Gulf War one of the big arms dealers shed some concern troll tears for the alliance forces because he was sure those 40 mile howitzers were going to make the difference in the battle. They didn't.
Bull had already done prison time for breaking laws during his dealings with South Africa, and was smart, so he tried some more dodgy things to get (at that time restricted) carbon for the projectile sheathing, and to smuggle the barrel sections out as oil pipes. These moves were detected. He was warned by intelligence services of the UK, US, and Israel, and he had no complaint coming, riding as he was with the outlaw.
Larry Hovis, an actor best known for a role in Hogan's Heroes, was one of Gerald Bull's pallbearers, if memory serves (two books around here somewhere, as usual, I can't prove it, although I may become a columnist for "Bad Housekeeping" magazine).
Yeah, but I was an artillerymen for 16 years and the only system I used that came even close to RAM-jet speeds was the Lance (MGM-52) missile, which would do mach 3 by the time it cleared the launcher. With 8”, 155mm and 105mm, I could see the rounds leaving the tubes and sometimes track them downrange. All of the RAM-jet tests I’ve seen were after the missile was accelerated to Mach5 with a SRB. I just can’t imagine a RAM-jet in a 155mm sized projectile or, really, any tube artillery projectile.
And artillery is on-call, 24/7 in ANY weather.
“...All of the RAM-jet tests I’ve seen were after the missile was accelerated to Mach5 with a SRB. I just can’t imagine a RAM-jet in a 155mm sized projectile or, really, any tube artillery projectile.”
I will defer to SJSAMPLE on the possibilities of fitting any ramjet-powered system inside a gun tube. I’m certain he’s correct.
Ramjets have been employed in hypersonic vehicle research, but not all require speeds that high to operate.
The 2K12 Kub (”Cube”) low/medium altitude SAM system developed by the USSR in the 1950s/1960s used a novel propulsion system: when its solid-fuel booster burned out, the cavity in the airframe thus created became a ramjet, sustaining the missile inflight. Max missile velocity was Mach 1.75 to 2.8, depending on variant.
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