Some more information about the jet-lift Handley Page H.P.120,
Source :- Putnam's 'Handley Page' pp. 579-82.
Following the start of the Shorts S.C.1 VTOL aircraft flight test trials in 1957/58, the Army became interested in a light scout vehicle capable of using the same techniques to cross otherwise impassable obstacles.
The Fighting Vehicle Research and Development Establishment [FVRDE] at Chobham, Surrey, issued Specification 92/58 for an
'Airborne Reconnaissance Vehicle with a crew of Two'; the (in)famous 'Jumping Jeep'.
The Handley Page company made a number of exploratory studies using jet-lift. in addition to the rotor-borne studies above.
The first series, H.P.112, were to use the RB.108, however the multiple engines required led to a too-complex installation, to be operationally acceptable.
However a second study, the H.P.118 'VTOL Jeep' from 1960, were based around the larger RB.162 of 4,400 lb static thrust.
This was still not enough, but in 1961 Rolls-Royce offered a developed RB.162 with an additional top[front] fan producing 11,000lbs thrust.
This led to the H.P.120, on two versions. Type A was wingless, relying purely on jet-lift, for 'hopping', and short, low-altitude flights.
For land power, it would use a 100hp Coventry Climax 2 1/2 litre petrol engine, and four-wheel drive, giving 45mph on normal roads, and 25mph cross-country. Fuel capacity on land was sufficient for around 230 miles, in the air approximately 45 miles at low altitude in still air, or 50 'hops' of 1,000 yards.
The type B was to use folding wings and tail, along with jet deflection, to improve the the airborne performance, without compromising that on land.
The first version added a simple folding wing of 16' span and 144 sq ft area. This actually reduced the range to 40 hops or 37 miles.
Increasing the wing area to 178 sq ft and 27' span decreased performance still further, to 36 hops and 35 miles, even though limited thrust deflection was to be used.
Increasing the range of jet deflection to the horizontal more than doubled the airborne 'miles per gallon' and increased the range to 79 miles, without any loss of hopping ability. However, in order to achieve this, the engine needed to be throttled in horizontal flight, giving very poor sfc figures.
In order to correct this, the RB.162 was replaced with four RB.172 engines, each of 3,300lb thrust. This allowed an increase in take-off weight to 9,200lbs, from 8,000lbs while the vertical thrust remained 15% above the take-off weight.Performance was again increased, to 198 miles range, or 42 hops. Once again, the complexity of the engine installation was enough for rejection.
The final version considered was to be fitted with a single top-fan RB.162, and a horizontally mounted RB.172 engine for flight. This combination gave the best operational performance, and accordingly, was the version tendered to the requirement.
Unfortunately, when the top-fan RB.162, now renamed the RB.175, was finally run in 1962, it's thrust was only 8,800lbs, insufficient for the H.P.120, which was accordingly abandoned.
cheers,
Robin.
