Thomas P.M. Barnett :: Weblog

Some nice photoshopping, but I think Mr. Nelson is a little off on his numbers and has a bad idea overall.

The C-17 has an empty weight of 282,500 lbs, and a max take-off weight of 585,000 lbs. The max payload is 170,900 pounds and the average fuel load (for flying the airplane, not mid-air refueling ops) is between 170,000 pounds and 240,000 pounds. The math that Mr. Nelson uses doesn't appear to match up to the Air Force's stats.

As far as the "KC-17" idea, the design of the C-17 would have to be completely reengineered for it to be a refueling tanker, and the addition of a refueling boom at the rear of the aircraft would probably negate the ability to load and offload cargo via the rear cargo ramp. The loss of the rear cargo ramp would take away the ability to carry pallets, rolling stock, and outsized cargo. Also, if they were converted to be used as a refueling tanker, they probably wouldn't be used for fire-fighting because you wouldn't load water into tanks that typically carry jet fuel! There's a reason why you don't see refuelers like KC-10s and KC-135s being used to fight fires.

Using the C-17 to fight fires is a good idea, and I'm sure it wouldn't take too much to come up with a larger version of the firefighting system that is loaded onto the much smaller C-130s. The current inventory of C-17s are in high demand for strategic airlift around the world though, so it would be tough to task them to firefighting duty at this time.

I appologize if my ideas are a little jumbled, but I think this is truly an amateurish idea, and far below the level of thought usually presented in this blog.

Not a bad idea.... Though with a unit cost of $237 million for the strictly cargo role vs. the roughly $108 million for the KC-45/KC-767, compelling arguments for reduction in unit costs/overall cost/performance will be critical.

This looks like a great idea and seems much more cost effective than the KC-45. I do have one question. Would a KC-17 also eliminate the need for a KC-777 or would they work in conjunction like the current KC-135 and KC-10?

I'm not an expert on the unit cost details of either of these platforms but this wiki URL pegs the KC-45 at $200M each (http://en.wikipedia.org/wiki/KC-45) and this one pegs the C-17 at $218 (http://en.wikipedia.org/wiki/C-17_Globemaster_III) which is within 10%.

Adding a tanker "kit" would obviously increase the baseline, but I would argue this would be well offset by the superior flexibility. How much did the San Diego wildfires cost us 2 years ago? How much is Yellowstone or Yosemite worth? What's the marketing good will value of international disaster relief? Hard to peg with exact dollars I admit but quite valuable for sure.

The only problem I see is political. Already, whenever there is a homeland natural disaster, anti-war folks blame the president for not having the national guard home to help. Same thing would happen here. I imagine converting from KC refueling mode to firefighting mode would involve some serious hardware changes. By the time these planes were flown back from the Gap and had their booms swapped for large doors, the fires would be much worse. This may also limit a multi-role plane to the National Guard if it's expected to help in disaster relief.

Of course, by the time these things are built, these concerns could be worked out.

One question I have is, how common are forest fires outside of the US? I never see news coverage about forest fires unless it's the Western US. I'm just wondering how much of this disaster relief would end up being "international". It could be one bad-ass crop duster though! ;)

Why not take it to the next step? With this being the 6th year in a row, why can't Californnia buy the tankers and have them outfitted for firefighting? Better yet, why not form a consortium of fire prone states and purchase the tankers as a copperative? Recall that Florida almost burned off the map a few years ago. They could then enter into a lease agreement with the USAF allowing the Air Force to use them during the non-fie season (assuming there ever is one).

One thing to consider is how the decision wll be made regarding where the tanker is used. Having gone through Katrina I heard all of the arguments that the National Guard shhould not have been in Iraq but rather at home performing hurricane duty. I can imagine similar arguments if the tankers are in the Arabian Gulf and fires are buring in San Diego.

But I admit, I do like this kind of thinking!

semi-ignorant question i'm not taking time to research right now: isn't the bigger part of this problem building non-fire-proofed houses in fire-prone areas? or building non-hurricane proofed houses in hurricane-prone ares, etc?

i'm not talking about thousand year measures (to obviate New Orleans or 2008 Eastern Iowa floods, but what about better 100 year and 10 year countermeasures?

I keep reading about "26 Pentagon requirements" for the tanker contract but can't find any details on them. Maybe they are classified. That might help us understand if the C-17 could even qualify. Too bad the C-5 fleet is too old. It'd be cool to just pop that nose open and slide in either a tanker module or a fire fighting module. ;)

Robert, armies may crawl on their stomach, but air forces fly with their tanker fleet. Tanker missions don't take a break during the fire season, so leasing from state governments seems it would do little good. Also, I assume the craft would have to be manned by US Air Force crews and meet all military specs and paint schemes.

Sean, your point is very Bjorn Lomborg-esque! Sure, let people build them, but don't give them federal relief when they fall into the ocean, get knocked by hurricanes or flood. We basically have government subsidized high-risk behavior. Because we bail these home owners out, there is very little risk so they keep doing it.

However, this will only take care of property damage and slight chance of loss of life. Being from the Midwest, I'm also semi-ignorant on this but I'd assume that losing hundreds of acres of forest and wildlife is also a problem which means the fires still need to be fought.

Good comments all. I suspect international wildfires are a significant issue too, so this is definitely a factor worth considering. My guess is that it could easily be 5-10 X the level of US concerns.

With respect to configuration for this mission, US wildfires have a very predictable season, so a reserve fleet could easily be coordinated to address anticipated demand. This way the only time you would encounter re-configuration issues would be when needing to surge additional airframes for an extraordinary event. And, I would argue that this this fleet would then be an ideal resource for keeping air guard crews proficient in high intensity missions vs. their typcial air truck role, so this would serve a militarily relavent training role too.

I also suspect support for refueling AND fire mode may be quite easy to actually design into a common configuration to. All it really needs is a monster dump valve in addition to. the air-to-air boom and trailing probe plumbing. You would most definitely need to flush the tanks between these missions though : )

With regard to State ownership of this requirement I just don't see them ever being able to assemble a platform in the critical mass that the Air Force can. Especially as this is just a seasonal mission.

To the building code comments I agree this is a good thing to promote but a lot more burns than just the housing type infrastructure. Your talking about power line right of ways that get destroyed, our national forrest and parkland resources, wildlife and their habitat destroyed, mudslide implications in burner out regions the next time it rains, etc., etc., etc.

BB: one of the best compliments i've ever gotten! ;-)

Mike: how much does housing and development add kindling and fire paths to nature?

BB, you forgot attack! Can you imagine the fun one can have designing an AC-5 configuration . . .

Jim F:

The blog, by definition, is for experiments and floating ideas. So please, no sancitity-of-this-site condemnations. I find most true innovation to be completely "amateurish"--and thank God for those willing to engage in it.

I wasn't trying to imply that the entire idea was amateurish, and in retrospect that was poor word choice. So I think I should say here that I'm sorry to have used that kind of wording. I think I just got a little caught up in the moment.

The idea to use the C-17 as a fire fighting platform is actually an outstanding idea if we have extra capacity that isn't being used up as strat-airlifters around the world.

I just don't think that the idea of a "KC-17" is feasible based on the way that the aircraft is designed, and it's especially not feasible to use a refueling tanker as a firefighting tanker. There are KC-130s out there, but they use a probe and drogue system that is mounted on the wings, and I don't think the C-17 has the capability to carry external fuel tanks on the wings.

I also read that they tried to shop the C-17 design around on the civilian side, but there wasn't much interest because the configuration they were selling it in is not as fuel efficient as the cargo hauling 767s, 777s, etc. Not sure on the accuracy of that, but take it for what it's worth.

Jim F:

While I am educated as a mechanical engineer I will admit that I am not a aero engineering expert so my math could indeed be wrong. However, I did perform some reasonable due diligence prior to posting this and believe I am in the ballpark at least.

The difference between our thinking I believe is you are interpreting the 296,000 lb fuel capacity I attribute to a KC-17 as the capacity for refueling alone, and thus want to add the KC-17s typical 170K-240K (your numbers) into the weight equation. My research indicates this is not how refueling tankers are spec'd. For reference please see the Wiki page on the KC135 here (http://en.wikipedia.org/wiki/Kc-135).

A quick review of the specs. for this aircraft reveal that the fuel capacity quoted in the PPT table for the KC-135 (200K lbs. which I got from a KC-45/KC767 comparison source) is essentially its fully loaded weight minus its empty weight (297K-98K ~ 200K)

I ran the same analysis on the KC10 to the same conclusion too. You can find data at these 2 URLs:

http://www.af.mil/factsheets/factsheet.asp?fsID=109)
http://en.wikipedia.org/wiki/KC-10

With regard to the loading ramp vs. tanker configuration issue I would argue that it would be a reasonably minor design exercise to address this concern. I base this on the fact that the cargo door is by its very nature a module that can be (reasonably) easily removed from the aircraft, so in the worst case you would have a complete aerial tanker module that replaces the entire door assembly when in this configuration. More likely I expect you could design a boom mount that protrudes through a port in the base of a modfied door, use a palletized tankage system in the cargo hold, and likely use the same port feature for the Fire Tanker dump valve. In this way conferting between missions would be a reasonably simple change of external plumbing that hangs off of this port.

Just FYI I also found a reference to a KC-17 as a "Known Varient" of this aircraft at the following URL, but could find no other references to such a configuration. I admit I am presuming a bit here but think I'm on fairly good ground.

http://www.aerospaceweb.org/aircraft/transport-m/c17/

With regard to the use of common tankage for both refueler and fire tanker I stand by my assertion. Of course there would need to be design provisions for this (materials selection primarily) but a liquid cargo is a liquid cargo, and there would be great value (in procurment efficiency AND operational flexibility) in a common infrastructure here. In fact, truck tankers commonly revert between benign payloads such as corn syrup etc. and much more dangerous substances, and that is why they have the modular fold-over metal signage to indicate what they are carrying (in case they are in an accident and emergency personal need to respond).

Jim F, thanks for the more moderate words. i had no problem with your criticism but want the tone on the website to be very high.