sprstdlyscottsmn wrote:320kt TAS is way too slow for tactical aircraft max range cruise. 320 is closer to the IAS.

Alt 30,000ft

320KTAS-----494KTAS

200KCAS-----320KCAS

0.543M-------0.838M

Alt 36,000ft

320KTAS-----541KTAS

180KCAS-----320KCAS

0.558M-------0.943M

Alt 40,000ft

320KTAS-----585KTAS

164KCAS-----320KCAS

0.558M-------1.020M

Best LOITER was given as 32,000ft, 0.75M (438KTAS, 271KCAS), with about 4,600pph in the F-35A with this stated to give a total of 4 hours of fuel. Obviously you don't get to use all 18,400lb of fuel in loiter but as you get lighter you burn less fuel and go up in altitude.

Absolutely agreed. The question is whether its theoretically possible for the C to have 2.5 hrs (or close to) TOS. Of course it can with the assumptions of higher altitudes with a very low loiter speed for max end. The assumption of 320 kts is of course valid for the question. As already mentioned, its not going to happen in actual ops but that's not the question here.

sprstdlyscottsmn wrote:Also, you are using an F-35B chart to infer information about the F-35C. Their climb/cruise/descent profiles will be vastly different due to the wing. Even so, the 1,304nm you are assuming for cruise would be closer to 2.4hr endurance using 320KCAS at 36,000ft.

No other publicly available chart available. All 3 variants are using the same engine so fuel use rates should roughly be about the same. Agreed wing affects climb and descent rates but difference on range won't be materially far off.

What I like about the chart is it explains the fuel burn rate is based on a training profile for a sortie (minus actual ops). So theoretical max endurance fuel burn rates will probably be a slightly lower consumption figure.