Praga B2
B2 | |
---|---|
Jowett-Praga B on display at theShuttleworth Collection | |
Type | Air-cooled flat twin |
National origin | Czechoslovakia |
Manufacturer | Praga, Ceskomoravska-Kolben-Danek Co. |
Number built | 135 |
ThePraga B2was a low poweredaero enginesuitable for very light aircraft. It dates from the mid-1930s.
Design
[edit]The Praga B2 was a dual ignition, air-cooled horizontal twin producing 40horsepower(30 kW) aimed at lightweight aircraft.[1]It was a highercompressionversion (6.7:1 from the earlier 5.72:1) of the original and otherwise very similarPraga B,[2]which provided 36 hp (27 kW). Its cylinders[1]were machined from alloysteelforgings and hadaluminiumalloy heads. The pistons were of aluminium alloy, with three compression rings and one scraper ring. The connecting rods were of nitrided steel, with divided big ends andbronzebushes at the little ends.[1]The one piececrankshaftwas also formed from nitrided steel and had two main roller bearings and a single ball thrust bearing.[1]The single piececrankcasewas cast from an aluminium alloy.[1]
135 units in all, including B and B2 variants were built.[2]Jowett Cars Ltd. of Idle,Bradfordin the UK obtained a licence in 1936 to build the Praga B engine, for installation into the licence built Hillson Praga. Immediately after the end ofWorld War IIthe Praga B2 was on display at the 1946 Paris Air Show.[3]
Applications (B & B2)
[edit]- de Schelde Scheldemeeuw
- de Schelde Scheldemusch
- Hillson Pennine
- Mignet Flying Flea
- Praga E.114/Hillson Praga
Specifications (B2)
[edit]Data fromGrey 1972 p.32d
General characteristics
- Type:2-cylinder horizontally opposed
- Bore:105 mm (4.13 in)
- Stroke:110 mm (4.49 in)
- Displacement:1.906 L (116 cu in )
- Length:610 mm (24.0 in)
- Width:854 mm (33.6 in)
- Height:515 mm (20.3 in)
- Dry weight:48 kg (106 lb) (with airscrew hub)
Components
- Valvetrain:Two alloy steel valves per cylinder at 50°, aluminium-nickel-bronze valve seats. Two ball bearings to each rocker arm, grease gun lubricated in oil tight rocker-box. Push-rods and tappets in aluminium sleeves.
- Fuel system:Zenith 42M, mixture passing through sump in pipe to avoid condensation. Two BTH magnetos supplying two plugs/cylinder.
- Oil system:Integral with 4.5 L (7.9 pt) sump. Pressure and scavenge pumps, filtered; pressure feed to big and little ends.
- Cooling system:Air-cooled, finned cylinders
- Reduction gear:Direct, right hand tractor.
Performance
- Power output:31.1 kW (41.7 hp) at 2,440 rpm
- Specific power:16.3 kW/L (0.36 hp/cu in)
- Compression ratio:6.7:1
- Fuel consumption:at 2,440 rpm 9.38 kg/h (20.68 1b/h)
- Specific fuel consumption:0.225 kg/hp/h (0.495 lb/hp/h)
- Oil consumption:0.2-0.3 kg/hp/h (0.44-0.66 lb/hp/h)
- Power-to-weight ratio:0.65 kW/kg (0.4 hp/lb)
See also
[edit]Related lists
References
[edit]- ^abcdeGrey 1972,pp. 32d
- ^abPraha historyArchived2008-09-13 at theWayback Machine
- ^Small engines at Paris ShowFlight21 November 1946
- Grey, C.G. (1972).Jane's All the World's Aircraft 1938.London: David & Charles.ISBN0-7153-5734-4.
Further reading
[edit]- Bridgman, Leonard, ed. (1947).Jane's all the World's Aircraft 1947.London: Sampson Low, Marston & Co. p. 37d.