The Falstaff rocket was derived from a proposed Hypersonic Research Vehicle (HRV) , Hyperion, itself based upon the UK’s largest operational solid propellant motor, Stonechat.
At the beginning of the 1960s, the Rocket Propulsion Establishment (RPE) undertook research to determine how large a rocket motor could be produced using plastic propellant technology. This research program resulted in the development of a 36-inch (914 mm) diameter motor. When the planned Hyperion vehicle required a larger motor than was currently available, in order to achieve its desired performance, the motor research was used to develop the Stonechat, itself a 36-inch booster. Three variants of the Stonechat motor (I, ‘Short Burn’ and II) were actually developed and tested.
Stonechat I, with 4,030 kg of plastic propellant, delivered a total impulse of 8.34 MNs in 32.3 seconds. Only one unit was flight tested as a booster for the original Falstaff vehicle. This vehicle comprised a Stonechat I motor, fitted with the four-fin assembly designed to stabilise the Hyperion HRV (4.42 m span), and a payload section with a simple concrete ballasted (1 ton) conical nosecone. Weighing about 7 tons , the vehicle was flown in October 1969 from Woomera. The first Falstaff flight proved to be successful in all respects. It was eventually designated as 'F00' in order to show its relationship to the later programme.
The Hyperion was intended to consist of a ‘Short Burn’ Stonechat 1st stage, with either a Rook or Raven 2nd stage and a potential Cuckoo 3rd stage. The ‘Short Burn’ Stonechat differed from the Stonechat 1 in its use of a faster burning propellant (17.7 s) and a slightly larger nozzle. Design studies for the Hyperion were completed when the RAE’s hypersonic free flight program was cancelled in 1970.
At the same time that the Hyperion project was being abandoned, RAE was seeking a test-bed rocket in connection with the
program that would come to be known as Chevaline. The Chevaline program, initially code-named Super Antelope, was the
British Polaris missile improvement program, intended to upgrade the missile defence system with penetration aids and a
greater degree of hardening. The test program required a relatively cheap launcher capable of lifting a 1,000 kg payload to
an altitude in excess of 100 km. It was determined that an 8% increase in the Stonechat I motor’s total impulse would be
necessary to meet the demands of the program. This performance was obtained by increasing the propellant density in the
existing motor casing, thus creating the Stonechat II. The new version was loaded with 4,360 kg of propellant and delivered
a total impulse of 9.61 MNs in 32.8 seconds.
The operational Falstaff vehicle was to be an unguided fin-stabilised rocket. The experiments would be attached to the top of the Stonechat II motor via an adaptor bay, which could support a larger 54-inch (1.37 m) diameter nose section. The payload was envisaged as a controlled manoeuvrable platform from which a variety of simulated experimental sub-munitions and decoys could be dispensed, along with a Prime-body for close observations.
In 1971, the Falstaff testing program, designated CQ941, was envisaged as comprising up to 10 flights from 1974. Actually, 7 launches were carried out between 1975 and 1979. The first two proving flights (F0 and F01) were intended to demonstrate the in-flight separation sequences and the correct functioning of the payload attitude control. Falstaff F1, launched in May 1978, was planned to be the first flight carrying active experiments, payload manoeuvres and dispensing sub-payloads. Unfortunately the flight ended in the destruction of the motor and the total failure of the test. The second operational experiment, F2, that reproduced the F1 flight program with an additional payload manoeuvre, was fully successful. Flight F3 extended the experimental program by including the release of the Prime-body for observation. The vehicle performed satisfactorily, but the payload failed. The F4 experiment program was similar to F3, with more manoeuvres but no sub-payloads. It achieved most of its objectives, although the payload stabilised at an incorrect roll angle. The last vehicle, F5, had the same experiment sequence as the two previous flights, but with a maximum payload dropped. This mission was totally successful.
Stonechat-Based Sounding Rockets
In addition to their use on the Falstaff vehicle, Royal Ordnance and BAe spent many years investigating the potential
use of Stonechat motors on sounding rockets and space launchers.
In 1972-1973, the Stonechat motor was suggested for two Skylark sounding rocket variants, Skylark 8 and 9. Skylark 8 would have been a 2-stage rocket with a Stonechat II 1st stage and Waxwing motor, inherited from the Black Arrow launcher, as a 2nd stage. Skylark 9 would have been a single-stage Stonechat II vehicle. Both vehicles were intended to be stabilized by three fins (a common Skylark pattern), instead of the four used on the Falstaff.
In 1980, another Stonechat-based Skylark design, Skylark 17, was produced in response to ESA's requirement for a vehicle capable of generating 15 minutes of microgravity for a payload of about 350 kg. A 2-stage vehicle consisting in a Stonechat II first stage topped by a Mage II motor was proposed. This proposed sounding rocket was not selected by ESA, losing out on the grounds of price to the US-built Castor IVB motor.
Stonechat-Based Space launchers
From the latter part of the 1970s, Royal Ordnance investigated the development of light space launch vehicles, based on
the use of the Stonechat motor. Skylark 13 and Spacelark were early generic names applied to a variety of light launch
In 1987 Royal Ordnance unveiled a family of light space vehicles named Small Orbiter designed for placing small payloads into LEO. This family would be composed of four versions allowing the launch of payloads from 20 to 200 kg to a 200 km orbit. The most powerful version was the 4-stage Small Orbiter 4, which would use a cluster of four Stonechat motors as a 1st stage, a single Stonechat as 2nd stage and a shortened Stonechat (2/3) as 3rd stage. The 4th stage would be a Waxwing motor.
Although Royal Ordnance did not obtain the financial support of the BNSC in order to proceed with the development of the Small Orbiter series, in 1988 another British company, General Technology Systems (GTS), proposed a similar project named Littleo. This 4-stage vehicle would have used a cluster of six Stonechat motors in its 1st stage, and a single Stonechat as its 3rd stage. The second and fourth stages were to be powered by Italian-made solid motors, respectively an Ariane-4 booster and an Iris upper stage. Littleo was planned to be able to put a 300 kg payload into LEO, launched from the Andoya rocket range. In 1989, a new version of improved performance, was to use US-built solid motors only (Castor IV, Castor II and Star 48). The project was cancelled soon after.
|01 Oct 1969||WOO||Mk.I F00||Test vehicle||S|
|09 May 1975||WOO||Mk.II F0||Proving flight||S, 119 km|
|19 Feb 1976||WOO||Mk.II F01||id.||S, 117 km|
|23 May 1978||WOO||Mk.II F1||Manoeuvres + dropping||VF|
|15 Sep 1978||WOO||Mk.II F2||id.||S, 97 km|
|05 Dec 1978||WOO||Mk.II F3||id.||PF, 98 km|
|14 Feb 1979||WOO||Mk.II F4||id. + prime-body release||S, 93 km|
|04 Apr 1979||WOO||Mk.II F5||id.||S, 103 km|
left: original Falstaff; right: operational Falstaff