Press Releases

Alpha has key role in producing jet-powered bike

Key parts for a revolutionary jet-powered pedal cycle have been manufactured with the help of Harrison Lathes.

An Alpha 400 manual/CNC centre-lathe has been used to machine propeller shaft, diffuser, engine housing and other pieces of equipment on an experimental gas turbine assisted bike, capable of speeds of 70 miles an hour, designed and built by UK Northamptonshire-based firm Broom Development Engineering.

Broom is now planning to progress the prototype and produce a larger far more powerful jet-pedal bike capable of setting new world-records. The Alpha 400 will again play an important role.

It has been supplied by Datamach Ltd, Coventry-based rnachine tool distributors.

The lathe tackles a wide range of jobs in Broom’s machine shop, which provides design, prototyping and small volume manufacturing capability using modern techniques and technologies, with many ‘Blue Chip’ names as customers.

Broom’s first thrust-driven cycle - an experimental prototype - is based on the frame of a small-wheeled Moulton shopper’s bike, on which a small jet engine has been mounted at the rear. This has been ingeniously adapted from combining a model aircraft engine with a turbo-charger from a car. It generates 20lbs static thrust and turns over at 45,000 rpm with a maximum of 120,000 rpm. It will run for two miles on a full tank of Diesel.

The Alpha 400 has been working to tolerances of 1 - 2 thousands of an inch on machining various parts, mainly made from materials in aluminium and stainless steel.

Broom Development Engineering proprietor Mick Broom, a former professional motorcyclist who founded the firm in 1983, explained:“The bike was put together basically as a demonstration model to show how thrust produces movement. “We are planning to develop very small gas turbines for heat, power and other applications. It’s quite a challenge, tricky work. Accuracy and clearances are critical, and tolerances tight.“The bike engine meant we needed machining capability so that, not least, we could precisely match the intricate curve of the compressor blades, which are made from aluminium, with the special shape of the aluminium outer housing.“Now we’re looking at serious speeds, with a two-wheeled pedal cycle that has aerodynamic fairing and with thrust from either two or three outside jet engines at the back. It is serious research which, as well as speed, means that we can also study the effects of drag.“We are aiming for something that will not just break records but will also give a safe and comfortable ride in an everyday normal road environment”.Preliminary designs are in place. The Alpha 400 will be shaping the aluminium road wheels, spindles, pins, various engine parts, and “all the geometry” on the planned historic super-bike project, he says.

Broom bought the Alpha 400 because of the benefit of adding CNC to workshop capability and because of its overall sturdiness. The firm operates CNC when this saves time, or when several complicated shapes have to be tackled, in which case information is downloaded via DXF file. Since much of the work is ‘one off’ or very low volume, CAM cycles are extensively used.

The Alpha 400 - in these different operating modes - is busy day-in, day-out on two existing core elements of Broom’s business -CAM cycles

Broom manufactures world-renown hand-made built-to-order Hesketh Motorcycles at the rate of one or perhaps two a year (the firm is located on Lord Hesketh’s estate at Easton Neston). They are assembled from 3,000 different parts. Broom also refurbishes and provides spares for existing machines. The company views each task as basically ‘one off’.

“We use the Alpha to machine everything from the headstock stems, right through to roughing out the camshaft blanks, and we do a lot on modifying existing designs and stock that’s perhaps been produced 20 years ago”, said Mick Broom.CNC

CNC mode comes into play for a larger but still relatively low volume specialised production run - for many parts for Broom’s Doodlebug, a lightweight foot-launched hang-glider which has a 120cc two-stroke petrol engine at the rear.

About ten leave the firm’s production line every month, and the machining process produces end components designed to match a ‘weight conscious’ product philosophy.

The Alpha 400 is programmed to take care of fittings on the Doodelebug’s fabricated aluminium tubeframe, housings and brackets, as well as other parts including three 7/8in steel rods which are then welded together to form the belt-driven propeller shaft.

On land and in the air, a Harrison Alpha is helping one pace-setting customer really reach for the heights!

Further Information

top