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Logistics Fuel Modelling: JP-5 and JP-8

 
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Logistics Fuel Modelling: JP-5 and JP-8 - 9/6/2020 11:26:20 AM   
tiag

 

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I watched recently the video by Donelly on the GUWS about logistics in wargaming and found interesting his comments on aviation fuel. I did not know that Naval Aviation branches uses JP-5, while JP-8 is used by the Army and Air Force. Did some research and it applies not only to USA branches, but also to other countries. Additionally, he comments that JP-8 can be generated from normal jet aviation fuel by adding some additives, while JP-5 cannot.
I was wondering, whether it would be interesting to distinguish JP-5 from JP-8 in CMO?! When modelling supplies in CMO for a long term campaigns, this would make things more real and for those into logistic simulation, this would make bring CMO closer to real world than it is right now.

A dirty way is via book keeping of fuel tanks using LUA, although it is tricky to make CMO choose the correct refuel for a given platform. @Devs: Is it possible/interesting to implement JP-5 and JP-8/Jet A?

Regards
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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/6/2020 1:16:02 PM   
AKar

 

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As far as I understand it, the sole reason for the use of JP5 is its reduced flammability which is a benefit when you look it from the point-of-view of the ship's damage control. All the carrier-borne assets that I'm aware of are happy to burn JP8 as well. For instance, the classic Hornet has a mechanical "selector" in its fuel control units that needs to be adjusted according to the fuel that is used. Hornets used by countries which fly exclusively from land-based airports only use JET-A1/JP8, but retain this control.

As you mentioned, JP8 can be mixed from the standard JET-A/A1, and this is regularly done for logistical reasons (it makes little sense for many to store JP8, instead they store JET-A1). I don't remember the specifics of the additive mixed in, aside that it was highly toxic, and I think its primary purpose was to reduce the growth of algae in the fuel system.

< Message edited by AKar -- 9/6/2020 1:21:12 PM >

(in reply to tiag)
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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/6/2020 1:55:36 PM   
Gunner98

 

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Wasn't aware there were two types in use but based on AKar's description, I don't think modeling it in game would be all that useful.

The one different fuel that might be worth modeling is JP-7 but only for the 30 odd years the SR-71 was in service. The Separate tankers KC-135Q/135T are represented and in reality are able to fuel anything including the SR-71 by switching tanks.

Best way of handling this now is keeping the SR-71 and the 135Qs on a separate non-player side, which is realistic anyway - but the SR-71 will go to any allied tanker unless you specifically tell it not to.

I don't think the juice is worth the squeeze though.

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/6/2020 3:26:10 PM   
AKar

 

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Technically I guess it is possible to run into situation where all that is available in a primarily naval airbase would be JP5 with an aircraft not certified for its use. I am not sure at all how commonly modern civilian + military turbine engines are certified for JP5. The good old PT6A at least, on the other hand, apparently burns it just fine. (The damned thing is even allowed to run on gasoline, for very limited periods of time.)

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/7/2020 10:48:50 AM   
boogabooga

 

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quote:

ORIGINAL: Gunner98

The one different fuel that might be worth modeling is JP-7 but only for the 30 odd years the SR-71 was in service. The Separate tankers KC-135Q/135T are represented and in reality are able to fuel anything including the SR-71 by switching tanks.


Agreed.

It's not just the fuel, though, but equipment, too. For example, the KC-135 is usually modeled in CMO as doing both probe and boom refueling, but as I understand probe capability comes from an add-on kit that is mutually exclusive with using the boom or from wing pods that only became available on some particular date. So whether it can do probe, boom, or both should be a loadout thing. Then one could consider that Russian probe refueling is probably not compatible with its US/NATO counterpart, etc.

quote:

I don't think the juice is worth the squeeze though.


CMO has a lot of features already that I would have said that for, but all of them added up is what makes CMO really special, IMO.

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/7/2020 11:08:29 AM   
boogabooga

 

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quote:

ORIGINAL: AKar

Technically I guess it is possible to run into situation where all that is available in a primarily naval airbase would be JP5 with an aircraft not certified for its use. I am not sure at all how commonly modern civilian + military turbine engines are certified for JP5. The good old PT6A at least, on the other hand, apparently burns it just fine. (The damned thing is even allowed to run on gasoline, for very limited periods of time.)


Keep in mind that aviation fuel does a lot more than just burn- heat sink/heat exchange fluid, lubricant, sometimes hydraulic fluid, etc. A fuel's physical properties matter.

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/7/2020 3:52:29 PM   
AKar

 

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quote:

ORIGINAL: boogabooga


quote:

ORIGINAL: AKar

Technically I guess it is possible to run into situation where all that is available in a primarily naval airbase would be JP5 with an aircraft not certified for its use. I am not sure at all how commonly modern civilian + military turbine engines are certified for JP5. The good old PT6A at least, on the other hand, apparently burns it just fine. (The damned thing is even allowed to run on gasoline, for very limited periods of time.)


Keep in mind that aviation fuel does a lot more than just burn- heat sink/heat exchange fluid, lubricant, sometimes hydraulic fluid, etc. A fuel's physical properties matter.

Yes, that's right, I'm well aware. In aforementioned classic Hornet, it is used for cooling the afterburner fuel system by circulation and dumping the heat in fuel-air heat exchangers located near the "elbow" hard points. One usually does not find such fuel cooling systems anywhere but in military aircraft. Yet, this is done reliably with just JP8 as well. The specific heat capacity of the fuel is probably pretty much the same, what other physical property matters is the volatility / vapor pressure. I've not googled up the specs, nor I know if there is any aircraft certified to operate on JP5 but not on JP8, hence perhaps making this point relevant. It would be interesting to know!

< Message edited by AKar -- 9/7/2020 3:53:33 PM >

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/7/2020 4:17:17 PM   
thewood1

 

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I don't know about this. It seems to be the slippery slope that was discussed several years ago. What about engine spares, turbine blades, actuator spares, food, toilet paper, etc. Where does the demand for counting rivets stop? I think a general logistics rating or supply availability is a much less complicated approach.

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/8/2020 2:20:28 PM   
c3k

 

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Most military aircraft can burn any JP fuel. There may be long-term effects and the off-spec fuel may yield lower thrust or require a higher burn rate, but a turbine can burn multiple fuels.

I do not think it would be worthwhile to track JP4/5/8 differences for the game. But, if someone does all the work for that, then I'd hope there's a toggle to turn it off for those who don't want to dive too deeply into the logistics rabbit hole. (If an aircraft burns off-spec fuel, will you track engine wear? What if it's just one tank of "bad" fuel? Etc.)

My .02.

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/8/2020 3:10:45 PM   
thewood1

 

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If "someone" wants to do all the work, I would expect other stuff that is more generally needed is going to get set aside.

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/9/2020 2:23:11 PM   
Gunner98

 

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This Webinar from Mr Hank Donnelly, Institute for Defense Analyses, on wargaming logistics for the Georgetown University Wargame Society talks about many things we chat about on these forums, but at ~27:40 he specifically talks about this question.

https://www.youtube.com/watch?v=4YVS-4tmzZg

His point is that it's very important but does you game/sim need the detail.... Which is I guess what we've been discussing above.

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/9/2020 2:33:42 PM   
SeaQueen


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For the typical Command scenario, it probably doesn't matter that much.

There's also other different logistical requirements for the Navy/USMC versus the Army and USAF beyond fuel. In very real sense, they have incompatible supply chains. The good news is that Command doesn't do much beyond the 12-24 hour time frame well without some pretty extensive LUA scripting so supply chains aren't really an issue. A good game might be about protecting a supply chain, but exactly what the packing list includes probably isn't important on the time scale you're concerned about.

The other good news is that if a jet is fueled with JP-5, it can take JP-8 and vice a versa. In the end it's all just kerosene with different additives for safety requirements. The constraint isn't about burning the fuels, it's about storing them. That's why a Navy aircraft can refuel from Air Force tankers.

Where would it be interesting / important?

If you were to construct a series of scenarios, assembled into a campaign, it might matter more, however, there are other mays to represent logistics. I believe you can, for example, set the keystore to exchange information between scenarios. That way, if you lost the Navy's jet fuel storage at the SPOD (Air Force, you had ONE JOB!), a future scenario might, for example, have an increased number of aircraft in a "Maintenance" state due to the inability to fuel all the aircraft.


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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/10/2020 5:03:06 AM   
Zanthra

 

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I thought all the navy aircraft could fly with mixed JP-5 and JP-8 such that they could take off with JP-5, and refuel from tankers with JP-8. The problem being when it gets back to the carrier, the fuel has to be removed before the plane can go to the hangar deck, and any fuel they take out has to be stored separately due to the lower flash point. Even a few percent of JP-8 mixed with JP-5 substantially lowers the flash point of the fuel to make it significantly easier to ignite.

< Message edited by Zanthra -- 9/10/2020 5:04:33 AM >

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RE: Logistics Fuel Modelling: JP-5 and JP-8 - 9/12/2020 4:08:40 PM   
AKar

 

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quote:

ORIGINAL: Zanthra

I thought all the navy aircraft could fly with mixed JP-5 and JP-8 such that they could take off with JP-5, and refuel from tankers with JP-8. The problem being when it gets back to the carrier, the fuel has to be removed before the plane can go to the hangar deck, and any fuel they take out has to be stored separately due to the lower flash point. Even a few percent of JP-8 mixed with JP-5 substantially lowers the flash point of the fuel to make it significantly easier to ignite.

It makes an interesting question of what are the limitations for using JP8 in carrier-borne assets? Is there a limited total amount that can be stored under the deck, or how it goes?

It is not that the JP8 / JET A-1 was too flammable on its own, in comparison to stuff like gasoline, however, military aircraft are modestly 'leaky' in comparison, so some extra fumes may develop if JP8 / JET A-1 was brought under the deck in the aircraft tanks excessively.

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