Wheesley Under Performing

[Moesly_Armlis]

How does the Wheesley jet engine thrust output 135 kN at mach 1.7 at sea level (engine specifications from part listing) when I am only reaching an engine thrust of 119 kN at mach 1.8 only 267 metres above sea level. Does the vessel need to be skimming the waves to reach its engine thrust potential?

Javascript is disabled. View full album

Edited September 11, 2015 by MoeslyArmlis

[The_Rocketeer]

I'm talking about things I don't know about, but I believe when air-breathing/jet engines are over-speeding the thrust drops off to a flame-out. The best speed you can get out of an engine is not usually at it's max thrust, it's something a little after when thrust has decreased and drag increased to be equal. At max thrust, your aircraft would still be accelerating, so drag would gradually increase. By the time they're balanced, you're exceeding the max-thrust velocity of the engine, so its thrust has reduced.

I think that makes some sort of sense... doesn't it?

[Moesly_Armlis]

but I believe when air-breathing/jet engines are over-speeding the thrust drops off to a flame-out.

I was never aware of over-speeding and do not think it was the reason.

That vessel test was from a higher altitude and diving down until I reached that maximum of mach 1.8 with an engine thrust of 119 kN. The thrust increased as speed increased and altitude dropped. As the plane leveled the speed decreased and the thrust also decreased.

[NathanKell]

Density at 267m during the day at KSC is only 1.09kg/m^3, vs 1.225kg/m^3 (i.e. 89%) at sea level in reference conditions. You need to worry about the lower pressure at 267m, and the higher temperatures during the day at the equator.

[Moesly_Armlis]

Density at 267m during the day at KSC is only 1.09kg/m^3, vs 1.225kg/m^3 (i.e. 89%) at sea level in reference conditions. You need to worry about the lower pressure at 267m, and the higher temperatures during the day at the equator.

That seems very logical. For the next experiment will have to do some after dark flights.

[Moesly_Armlis]

Over-speeding, air density and temperature all have impact on the maximum thrust. Still unable to reach the specified maximum thrust.

The test at night did increase the thrust. Also the altitude is lower.

Maybe somewhere colder is needed to further increase thrust.

Thanks The_Rocketeer and NathanKell for the assistance.