Rockets: 2.75" FFAR vs. SNEB

[KJ_Lesnick]

How did the two compare in accuracy over range?

[Weaver]

It's going to be hard to find a definitive standard to judge the two by because, by 2017, 'FFAR' and 'SNEB' have become rocket standards, rather than rocket designs, and all they really tell you is whether they'll fire out of a US pattern launcher or a French one. There are, I think I'm right in saying, dozens of rocket families with probably over 100 different individual designs, that will fire from 2.75" tube and a great number, if not quite so many, that will fire from a 68mm tube.

Just as an example, the Canadian CRV-7 70mm (2.75") rockets have MUCH higher impulse rocket motors than most FFAR or SNEB pattern rockets and are consequently rated as being much more accurate over longer ranged than either, which is why the RAF adopted them as a UOR during the 1st Gulf War.

[KJ_Lesnick]

It's going to be hard to find a definitive standard to judge the two by because, by 2017, 'FFAR' and 'SNEB' have become rocket standards, rather than rocket designs, and all they really tell you is whether they'll fire out of a US pattern launcher or a French one.

What I mean is the following

• The Mighty-Mouse used by the F-89D, F-94C, F-86D, and F4D-1
  
• The rockets that were carried in the SNEB pack used by the English Electric Lightning
  

I'm also curious how the Hydra 70 compares...

[Weaver]

The Lightning's internal packs (the ones which could replace the missile support pack) didn't use SNEBs: they used Microcell 2"/51mm rockets, as did the Sea Vixen's. The pods used by FAA aircraft that look like a Matra 155 (i.e. "standard SNEB") pod but have three rings of tubes instead of two also used the 2" rocket. During the Falklands War, RAF Harriers had to be quickly cleared to carry the 2" pods because the SNEBs wern't resistant enough to RF interference (or wern't certified as such) to be used on an aircraft carrier. You'll recall the horrible accidents the USN has had with RF signals from radars setting off rockets...

IIRC, the general problem with the original Mighty Mouse rockets when applied to helicopters was that they'd been designed for launch from a high-speed aircraft and so didn't have enough acceleration to get clear of the rotor downwash before being blown seriously off course before they could be spun up to stabilisation rate by their fins. That lead to the introduction of more powerful motors and spin vanes in the exhaust (to get the rocket stabilised faster) on the Hydra 70.

[KJ_Lesnick]

The Lightning's internal packs (the ones which could replace the missile support pack) didn't use SNEBs: they used Microcell 2"/51mm rockets, as did the Sea Vixen's.

I didn't know that

During the Falklands War, RAF Harriers had to be quickly cleared to carry the 2" pods because the SNEBs wern't resistant enough to RF interference (or wern't certified as such) to be used on an aircraft carrier. You'll recall the horrible accidents the USN has had with RF signals from radars setting off rockets...

I though that was stray voltage caused by turning on the engine...

IIRC, the general problem with the original Mighty Mouse rockets when applied to helicopters was that they'd been designed for launch from a high-speed aircraft and so didn't have enough acceleration to get clear of the rotor downwash before being blown seriously off course before they could be spun up to stabilisation rate by their fins.

They'd corkscrew all over the place even when they had that going for them..

That lead to the introduction of more powerful motors and spin vanes in the exhaust (to get the rocket stabilised faster) on the Hydra 70.

Which seemed to have started being used in 1948...

[Weaver]

The Wikipedia page on the Hydra 70 is a little misleading. It gives the introduction date as 1948, but that was for the original Mighty Mouse FFAR which Hydra 70 replaced. Hydra 70 is significantly different from Mighty Mouse: it has angled rocket nozzles to spin it and three wrap-around fins rather than the four 'flick-knife' style ones on the Mighty Mouse. It also has a more powerful motor. I'm afraid I can't find an exact introduction date for the Hydra 70, but given that it was the result of Vietnam experience, I presume it must be some time in the 1960s.

[jcf]

Hydra 70 is the name for any rocket that uses the MK 66 motor.

From Andreas Parsch's Designation Systems page on the 2.75" rocket:
"The original MK 66 MOD 0 version was ready in 1972, but was not mass-produced. The first production versions
were the MK 66 MOD 1 for the U.S. Army and the later MK 66 MOD 2 for the U.S. Air Force and Navy. The MOD 2
(development and full-rate production beginning in 1981 and January 1986, respectively) made the motor HERO
(Hazards of Electromagnetic Radiation to Ordnance) safe. HERO safety prevents accidental ignition of the motor
by stray electromagnetic fields like those emitted by a radar. The MK 66 MOD 3 is a HERO safe version of the
MOD 1 for the Army. Development of the current MK 66 MOD 4, to be used by all armed services, began in 1991.
It entered full-scale production in December 1999, and is the current standard motor for U.S. air-launched
70 mm rockets. It has internal changes, including new initiator and igniter, for further enhanced HERO safety."