The heating of the Delta fuel increases the total energy of the system
The heat capacity of kerosene is like 2010 Joules per kilogram, which means that for a temp increase of say 16C, the additional energy would be 32,000 Joules per kg. But the heat of combustion is 43 megajoules per kilogram, so the increase is pretty small.
Could it be that the performance increase comes from the lowering of the viscosity, making the propellant pumps feed at a higher rate?
nope
Can you show your work or provide a citation?
There isn't really any work to show there.
The higher and lower heating values of kerosene combustion are 46.2 and 43.0MJ/kg respectively (sourced from wiki, sourced from NIST)
RP-1 has a specific heat of 0.45-0.53 cal/(g*K) or 1.88-2.22 KJ/kg*K sourced from Declassified Report #8926-065 From Convair on RP-1.
I just made a spreadsheet of prop mass-density-tank volume-temperature-etc that calculated total system energy based off of the documentation of RP-1 mentioned above; higher temperatures do not fare well. I do not know where Jim is getting this from, I EDIT:
AM must be missing something.
I don't know quite how the fourth stage is loaded, as it may use kerosene and LOX depending on the model selected for the mission.
The proton upper stage (breeze-M) uses UDMH/N2O4 and is fueled in a separate building (outside the integration building) before transfer to the launch pad.
You can see it on the left side of the integration building here : http://wikimapia.org/#lang=fr&lat=46.061469&lon=62.923862&z=17&m=b
As for the blocks DM-2/DM-2M (which use lox-kero as propellant), they must be fueled on the launch pad. And given the absence of external mast or umbilicals on the launch pad, I guess they might have either internal or external fueling lines going up on the launcher. (to be confirmed)
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its fueled using servicing platform arms on MST.
Guys, I LOVE this sort of discussion!
I recall that there is a 30-40 fps performance hit for early RP-1 loading
I recall that there is a 30-40 fps performance hit for early RP-1 loading
That's not inconsistent. For instance, perhaps early RP-1 loading still has the same propellant mass as late loading, so you'd get zero benefit from the higher density of cold RP-1 (also, you aren't loading more oxygen). Also, the ullage mass would be greater in the case of cold RP-1, since the pressurant would be denser (doubt this is a big difference, but you never know).
Propforce - 2/11/2006 1:13 PM
Just talked to my Delta II propellant guru ....
You were right, the RP is heated to increase the overall vehicle performance. Even though this reduces propellant density thereby reducing the total RP-1 loading, it still provides an overall vehicle delta-vee advantage.
This practice is opposite of what Atlas II and Sealaunch were doing, from what I understand. Both were chilling their propellants to maximize mass loading.
Now why the difference approach, that's a good question...
My guess would be that the differing approaches have to do with the fact that the Atlas and Zenit engines, which provide all or most of the liftoff thrust, are optimized for thrust while the Delta II engine, which provides less than 20% of the liftoff thrust on the "79XX" models, leans more toward vacuum optimization. Or, from another perspective, it is because the Atlas and Zenit engines burn a much higher fraction of total vehicle mass in fuel than the Delta II engine does, so fuel density is relatively more important for Atlas and Zenit while that extra bit of specific impulse is relatively more important for Delta II.
- Ed Kyle
I asked my grandfather and he said that they heated the RP-1 even in the early Thor and Delta days long before SSRMs were added later in the early Delta Letter series.
Could it be that the Atlas and Zenit engines transfer more heat to the RP-1 before it enters the injector (or possibly even before it enters the turbopumps) than does the Delta II's RS-27A, thereby reducing the disadvantage of chilling?
I recall that there is a 30-40 fps performance hit for early RP-1 loading
That's not inconsistent. For instance, perhaps early RP-1 loading still has the same propellant mass as late loading, so you'd get zero benefit from the higher density of cold RP-1 (also, you aren't loading more oxygen). Also, the ullage mass would be greater in the case of cold RP-1, since the pressurant would be denser (doubt this is a big difference, but you never know).
Why? The RP-1 cools off and the vehicle loses performance.
I recall that there is a 30-40 fps performance hit for early RP-1 loading
That's not inconsistent. For instance, perhaps early RP-1 loading still has the same propellant mass as late loading, so you'd get zero benefit from the higher density of cold RP-1 (also, you aren't loading more oxygen). Also, the ullage mass would be greater in the case of cold RP-1, since the pressurant would be denser (doubt this is a big difference, but you never know).
Why? The RP-1 cools off and the vehicle loses performance.
Indeed, for the reasons I outlined and you mentioned. But it's not inconsistent with the idea that a rocket designed with RP-1 sub cooling in mind might have improved performance with cold RP-1.
The propellant lines are not visible in that photo. That is only the launch mount.
Delta second stage uses storable propellants and are filled days before the final countdown and while in the MST using drag on lines
Just found some photos where I think these feeding lines may appear !
What do you think ?
I also realized that one of the "support pins" was smaller than the others. Any idea what's the different with the other supports ?
also to prevent installation except one direction.
Thanks Kyle,
I had a feeling that the 1st stage was filled from the aft bay.
I found this photo but the studs emerging from the "support arms" seem very small to me...
What about the upper stages ?
The propellant lines are not visible in that photo. That is only the launch mount.
Delta second stage uses storable propellants and are filled days before the final countdown and while in the MST using drag on lines
can they off load (from storage) the 2nd stage propellants at the pad if need be?
Thanks Kyle,
I had a feeling that the 1st stage was filled from the aft bay.
I found this photo but the studs emerging from the "support arms" seem very small to me...
What about the upper stages ?
The propellant lines are not visible in that photo. That is only the launch mount.
Delta second stage uses storable propellants and are filled days before the final countdown and while in the MST using drag on lines
can they off load (from storage) the 2nd stage propellants at the pad if need be?
It is just the reverse of loading
Propforce - 2/11/2006 1:13 PM
Just talked to my Delta II propellant guru ....
You were right, the RP is heated to increase the overall vehicle performance. Even though this reduces propellant density thereby reducing the total RP-1 loading, it still provides an overall vehicle delta-vee advantage.
This practice is opposite of what Atlas II and Sealaunch were doing, from what I understand. Both were chilling their propellants to maximize mass loading.
Now why the difference approach, that's a good question...
I asked my grandfather and he said that they heated the RP-1 even in the early Thor and Delta days long before SSRMs were added later in the early Delta Letter series.
If you load a given mass of fuel, then hot RP-1 will have more energy.
If you load by volume, then cold fuel has more energy, if you have enough oxygen to burn it efficiently. (The easiest way to see this is that you can fit something like 6% more fuel in. You can burn 1% of it to raise the temperature of the rest to that of the hot fuel. Now you have 5% more, equally hot, fuel). You would need to either load more LOX, or change the mixture ratio.
So presumably Delta-II loads by mass.