962 H. Von Schertel 
| GAS TURBINE ie 
simple cycle 
{ 
| 
1-4 
1:0 GAS TURBINE Pt AN 
eee =e, | : 
CONSUMPTION ~ l ; 
LB/B.H.P.-HR. 0-8 ie De ay ue 
GAS TURBINE 
3-stage compression with inter- 
cooling exhaust heat exchange 
0 10 20 30 40 50 60 70 80 90 100 
PERCENTAGE FULL POWER 
Fig. D2. Surface performance of air-breathing engines 
of the simpler cycles was just about offset by the engine room volume and weight saved, so 
that for ranges of up to 1000 nautical miles there was little to choose between the installa- 
tions; above this figure the more sophisticated units showed to advantage. However, in this 
design evaluation the installational size of the Diesel engine concerned cut the payload so 
much that its use could not be considered. 
This raises a further point, very much to the forefront of the engine designer's mind, 
that above a certain size, Diesel engine specifics — both weightwise and volumewise — 
greatly increase as high duty materials and associated workshop practices can no longer be 
employed. One British engine, for instance, uses 36 pistons and 3 crankshafts in order to 
get the largest engine size which can be made from the better class materials and precision 
methods of manufacture. It would, therefore, seem that apart from small, highly specialized 
or experimental craft, the gas turbine should really come into its own at shaft horsepowers 
of, say, 4000 and above for the type of craft the author discussed. 
Speaking very personally, I feel that no real progress will come with the adoption of 
the gas turbine for high-speed marine craft until units are designed expressly for this pur- 
pose, not merely rehashes of aero engines. The knowledge and facilities exist for design- 
ing and developing these units; the engineer should be given the opportunity of doing this 
at the earliest possible date. 
R. N. Newton (Admiralty Experiment Works) 
I would like to refer to two specific points arising from Baron Von Schertel’s excellent 
paper which bear directly upon the general comments | made concerning hydrofoil craft and 
GEMs in the discussion of Mr. Oakley’s paper on high-performance ships. 
