Looks like Coulson is converting 6 of the newer ex-WN 733s to air tankers to battle widlfires.

http://fireaviation.com/2017/05/21/coul ... r-tankers/

It's good to see some of the 733s getting a new lease on life

Spacepope wrote:

Looks like Coulson is converting 6 of the newer ex-WN 733s to air tankers to battle widlfires.

http://fireaviation.com/2017/05/21/coul ... r-tankers/

Since a number of SWA's 733s had winglets, wondering if these will be with, or without winglets?

tjwgrr wrote:

Spacepope wrote:

Looks like Coulson is converting 6 of the newer ex-WN 733s to air tankers to battle widlfires.

http://fireaviation.com/2017/05/21/coul ... r-tankers/

Since a number of SWA's 733s had winglets, wondering if these will be with, or without winglets?

No idea, however since there is no STC for a tanker conversion to begin with, there should be no issue doing one or the other.

Winglets are useless for waterbombers and are hence only there to jack up the residual value of aircraft, which is counter-productive when all you want is low capital cost.

The B737 makes a lousy air tanker with only 14 or so tons usable water capacity and an hourly drop.
Millions wasted on an aircraft that will do 2000-3000 drops before being scrapped, with only marginal effects on the fires.
For the same cost, you can get 6 x MI-26 that will each drop over 120 tons per hour accurately over the fires' front lines.

Waterbomber wrote:

Winglets are useless for waterbombers and are hence only there to jack up the residual value of aircraft, which is counter-productive when all you want is low capital cost.

The B737 makes a lousy air tanker with only 14 or so tons usable water capacity and an hourly drop.
Millions wasted on an aircraft that will do 2000-3000 drops before being scrapped, with only marginal effects on the fires.
For the same cost, you can get 6 x MI-26 that will each drop over 120 tons per hour accurately over the fires' front lines.

Yeah, but if the 733s are getting parked without the fuel tank inerting, the residual value is jack squat winglets or not. How's that MI-26 FAA certification going?

A tanker that can be used to carry passengers? Is it like one big onboard pool bar?

Some aircraft had fatigue and crack issues due to winglets, something I'm sure wouldn't do well under the street of firefighting

Waterbomber wrote:

The B737 makes a lousy air tanker with only 14 or so tons usable water capacity and an hourly drop.
Millions wasted on an aircraft that will do 2000-3000 drops before being scrapped, with only marginal effects on the fires.
For the same cost, you can get 6 x MI-26 that will each drop over 120 tons per hour accurately over the fires' front lines.

It would almost certainly be retardant drops, not plain water, and it's a similar capacity to Coulson's C-130s. Most of the aircraft that have been doing this role in the past have a lower capacity, as far as I know.

Also, even if pulling from a nearby lake, has the Mi-26 ever actually done the 8 drops per hour you claim?

dmg626 wrote:

Some aircraft had fatigue and crack issues due to winglets, something I'm sure wouldn't do well under the street of firefighting

the winglets caused fatigue & cracks? Increased stress in the wings to support winglets?

Waterbomber wrote:

For the same cost, you can get 6 x MI-26 that will each drop over 120 tons per hour accurately over the fires' front lines.

Would the CH-47 not be a better fit? While less capable it is a well known model. It will make finding personnel, maintenance and availability of spares a lot easier.

When push comes to shove it's better to have one (or two) Chinooks fighting fires then one Mi-26 waiting for spares.

iamlucky13 wrote:

Waterbomber wrote:

The B737 makes a lousy air tanker with only 14 or so tons usable water capacity and an hourly drop.
Millions wasted on an aircraft that will do 2000-3000 drops before being scrapped, with only marginal effects on the fires.
For the same cost, you can get 6 x MI-26 that will each drop over 120 tons per hour accurately over the fires' front lines.

It would almost certainly be retardant drops, not plain water, and it's a similar capacity to Coulson's C-130s. Most of the aircraft that have been doing this role in the past have a lower capacity, as far as I know.

Also, even if pulling from a nearby lake, has the Mi-26 ever actually done the 8 drops per hour you claim?

Retardant drops are mostly useless even on open grass fields. On a hot day, with a fire's hot frontline approaching, the retardant is dry by the time the fire reaches the drop area.
The only effective way to fight forest fires with aerial platforms is to extinguish the frontlines of fires and after doing that avoiding that they spark back on by extinguishing behind the frontlines.

Do the math: A 15 ton drop over an area of 30 meters by 500 meters, ie 1500 m² is just 10 mm/ 1cm / 3/8 in. of water/retardant per m².
Bear in min that
-in open grass fields, most of it will fall to the ground and be abdsorbed by the soil, with little to no effect on the grass which will repell the water (most dry grass is hydrophobic).
-in forest settings, nothing will penetrate the canopies and the fires will continue to burn from below
-in mild winds and 30°C + temperatures, any water or retardant that manages to stick to vegetation will be dry within 10 minutes.

Even the Mi-26 which can drop 20 tons in twin bambi's many times per hour over smaller area's and accurately has a hard time fighting even smaller fires, so never mind the nextgen tanker cough airshow cough program.

I don't know why they haven't invented some type of CO2 bomb for forest fires.

smokeybandit wrote:

I don't know why they haven't invented some type of CO2 bomb for forest fires.

Because that would be a great way to kill the firefighters working on the ground near the fire.

CplKlinger wrote:

smokeybandit wrote:

I don't know why they haven't invented some type of CO2 bomb for forest fires.

Because that would be a great way to kill the firefighters working on the ground near the fire.

It would probably also disperse too quickly to be effective.

Waterbomber wrote:

Retardant drops are mostly useless even on open grass fields. On a hot day, with a fire's hot frontline approaching, the retardant is dry by the time the fire reaches the drop area.

The water isn't the important part, although the thickeners they use slow the evaporation, in addition to their primary purpose of reducing drift, making it stickier and preventing runoff. Depending what exactly is used, the retardant itself coats the plant matter to reduce oxygen access, or react competitively with the oxygen and at lower temperatures that steal heat, or form an insulating char, or all of the above.

This is a demo of a similar product. I think that's lighter fluid they used halfway through to get the fire going again, and then once more later on:
https://www.youtube.com/watch?v=UqBn4LE-kVg

Water is, however, a critical ingredient for foams and gels, but those are used more for directly hitting hot spots or protecting structures than as a retardant. Depending on weather and application rate, foams and gels effectiveness as retardants is usually only a couple hours.

Waterbomber wrote:

Do the math: A 15 ton drop over an area of 30 meters by 500 meters, ie 1500 m² is just 10 mm/ 1cm / 3/8 in. of water/retardant per m².

It can be less, depending on what they're doing. 3/8" of liquid coming down in a single drop is an incredible drenching. It's like a few hours of light drizzle compressed into a few hours.

CplKlinger wrote:

smokeybandit wrote:

I don't know why they haven't invented some type of CO2 bomb for forest fires.

Because that would be a great way to kill the firefighters working on the ground near the fire.

Well obviously you wouldn't deploy them where it could kill people.

The winglets put stress on the center wing box due to the additional lift flexing the wings up.
Why not use the later -700s that were designed with winglets in mind? They're cutting a bunch of them up in TUS right now.

avioniker wrote:

The winglets put stress on the center wing box due to the additional lift flexing the wings up.
Why not use the later -700s that were designed with winglets in mind? They're cutting a bunch of them up in TUS right now.

A "bunch" is a bit of an exaggeration as not many 700's have been scrapped at TUS and I can think of only 4 recently including two 9 year old ANA birds

Waterbomber wrote:

Winglets are useless for waterbombers and are hence only there to jack up the residual value of aircraft, which is counter-productive when all you want is low capital cost.

The B737 makes a lousy air tanker with only 14 or so tons usable water capacity and an hourly drop.
Millions wasted on an aircraft that will do 2000-3000 drops before being scrapped, with only marginal effects on the fires.
For the same cost, you can get 6 x MI-26 that will each drop over 120 tons per hour accurately over the fires' front lines.

737 vs. MI-26

Teenagers are out of school it seems.

News article with photo.

http://www.timescolonist.com/business/i ... 1.20212148

Looks like N617SW is the first of the 6. Not exactly young and spry, she had 67000 hours and 53000 cycles on her as of January.

Spacepope wrote:

Looks like N617SW is the first of the 6. Not exactly young and spry, she had 67000 hours and 53000 cycles on her as of January.

But young by WN standards

n471wn wrote:

Spacepope wrote:

Looks like N617SW is the first of the 6. Not exactly young and spry, she had 67000 hours and 53000 cycles on her as of January.

But young by WN standards

Yes but now we're full into "grading on a curve" territory.

Id like to see the AN225 converted to a water tanker. Wonder how much it could drop.. ok back on topic- I think the 733s would be sitting or scrapped otherwise so i guess its a good thing

n471wn wrote:

Spacepope wrote:

Looks like N617SW is the first of the 6. Not exactly young and spry, she had 67000 hours and 53000 cycles on her as of January.

But young by WN standards

If they combine the conversion with a D check, the planes could could fly for many years to come till they time out again.

ChrisFallon77 wrote:

Id like to see the AN225 converted to a water tanker. Wonder how much it could drop.. ok back on topic- I think the 733s would be sitting or scrapped otherwise so i guess its a good thing

Given the AN225's size/weight capacity ... someone do the math on flow rates and how long that load would take to pump onto the airplane ...

A quick update: The first 733 tanker (Tanker 137) is painted and ready for tank installation. Winglets are indeed still there. http://fireaviation.com/2017/05/25/phot ... ir-tanker/

Am I the only once concerned with having such a high cycle airframe perform water drops. The C130 crashes come to mind or is the 737 a more resilient frame?

flyingcat wrote:

Am I the only once concerned with having such a high cycle airframe perform water drops. The C130 crashes come to mind or is the 737 a more resilient frame?

There was more than one C-130 tanker crash? I'm only aware of the HP one. In that case, many C-130s have had center wing box replacements and are still on the firelines. Coulson just trucked a C-130Q to Mesa for conversion (their second -Q) since good flying ones are impossible to find.

Southwest has been flying passengers in 733s with half again as many cycles on them so I don't think there will be many issues.