As an example case for me and others.
Monogram made a 1/121 B-58 and Revell made a 1/94 B-58.
B-58 engine is a J-79. Found that J-79-GE-17 is rated: 11,905 lb dry; 17,835 lb with afterburner.
Transfered to a 1/72 model what are approx ratings for Monogram and Revell engines ?
Thanks
Bill
Okay so by the empirical method:
A J-79 is 5.3m long and 1m wide. Bear in mind that all J-79s were afterburning, which adds considerable length to the engine. A CJ-805 (civilian J-79 without afterburner) is just under 3m long (without hush kit or thrust reverser)
The Revell engine in 1/72nd would be just over 4m long and 0.76m wide. A fair equivalent would be the Bristol Orpheus. This was 0.82m wide but of simpler technology, so the scaled J-79 should be a fair match for it. The basic Orpheus was 1.9m long, but there was an afterburning version whose length I can't find, but which you'd expect to be in the 3.5 to 4.5m range. This engine put out 6,800 lb dry and 8,170 lb in afterburner, and since it's development was never finished, you could reasonably project that later versions would do better than that.
The Monogram engine in 1/72nd would be 3.15m long and 0.6m wide. The Turmansky RD-9 is probably the nearest thing dimensionally at 0.67m wide, and that put out 6,600 lb dry and 8, 300 lb with afterburner.
You can see from this that the real world equivalents of both scaled engines overlap considerably in thrust values, which just goes to show that thrust is only approximately equivalent to engine size anyway: there are lots of other factors that can affect it. In particular, afterburners can range in power from those that only add a modest amount of thrust to those that nearly double it.