Author Topic: New F9 Upper Stage  (Read 7390 times)

Online AncientU

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Re: New F9 Upper Stage
« Reply #20 on: 05/19/2017 09:52 AM »
He did throw out 42*.
Engine number on ITS...

* and chuckled
« Last Edit: 05/19/2017 09:53 AM by AncientU »
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Offline tdperk

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Re: New F9 Upper Stage
« Reply #21 on: 05/19/2017 11:21 AM »
What if he threw out "42"? I think it very might well cause actual seizures...

If he says it while having a towel thrown over his shoulder and a bag of herring in his pocket, I will be deeply worried...

...about how to get past the leopard.

Offline MP99

Re: New F9 Upper Stage
« Reply #22 on: 05/20/2017 05:24 PM »
I5F4 also accelerated through transonic much more aggressively than SES-10, which is interesting.

From the comparison graph, I5F4 flew a more lofted trajectory, so maybe transonic happened at higher altitude, lower dynamic pressure?

I would assume that the reason for SES-10's flatter trajectory is to reduce re-entry heating as it was flying to ASDS not taking a one-way trip like I5F4.

From the earlier posts, if extreme subcooling allowed for a greater prop load, the increased GLOW would have reduced acceleration. If it's correct that acceleration was greater on this flight, then that would (also?) imply greater thrust?

If acceleration was notably greater on this flight, then perhaps a more lofted trajectory was necessary to avoid very high maxQ aero loads.

Cheers, Martin

Offline orulz

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Re: New F9 Upper Stage
« Reply #23 on: 06/14/2017 01:01 AM »
The maximum flow rate of the turbopumps is measured in terms of volume of propellant, not mass, right? The same volume of denser, colder propellant flowing through the pumps would mean more propellant mass which would by definition mean more thrust, right?

Online envy887

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Re: New F9 Upper Stage
« Reply #24 on: 06/14/2017 02:14 AM »
The maximum flow rate of the turbopumps is measured in terms of volume of propellant, not mass, right? The same volume of denser, colder propellant flowing through the pumps would mean more propellant mass which would by definition mean more thrust, right?
Pushing more mass through a sonically choked nozzle requires more pressure. Pumping more mass into a chamber​ operating at higher pressure requires a lot more power, which has to come from the gas generator turbine. Getting more power from a turbine means running it at higher temp, pressure, speed, or all three... The turbine durability is probably the limiting factor here.

Offline Robotbeat

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Re: New F9 Upper Stage
« Reply #25 on: 06/14/2017 02:24 AM »
The maximum flow rate of the turbopumps is measured in terms of volume of propellant, not mass, right? The same volume of denser, colder propellant flowing through the pumps would mean more propellant mass which would by definition mean more thrust, right?
Correct to first order.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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