Water injection afterburner?

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David E. Powell

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Sep 9, 2010, 4:45:01 PM9/9/10
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Looking at the "water cooled turbine" stuff in the "US Jet Engine
1940" thread, it got me thinking:

Given that water that flashes to steam can really expand, was a water,
water-glycol or water-alcohol mix ever considered for an afterburner?
Heat up the nozzles in the jet exhaust pipe, and then inject water/
glycol as needed? Instead of fuel, good old water gets used. Steam
trail should be huge, but otherwise it may be doable, though the
pressures generated would be pretty huge.

Ed Rasimus

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Sep 9, 2010, 4:54:29 PM9/9/10
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You note the issue of pressures to contain the steam, but there's also
the question of sustaining the temperature in the tailpipe. Injecting
water into jet exhaust would have a significant cooling effect and
that would degrade your steam generation pretty quickly.

Water injection was employed to increase the mass of effluent. We had
afterburner water injection on the J-75 engine of the F-105. A 38
gallon tank of water was mounted above the A/B section and after
burner ignition on take-off roll, the water would provide an extra
2000 pounds of thrust, which is less than 10% of total engine thrust.

The water tank was not stressed for manueving flight and any water not
expended on takeoff was jettisoned.

The KC-135 had water injection to the basic engine.

Ed Rasimus
Fighter Pilot (USAF-Ret)
www.thundertales.blogspot.com

kirk....@gmail.com

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Sep 9, 2010, 5:10:16 PM9/9/10
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On Sep 9, 3:54 pm, Ed Rasimus <rasimusSPAML...@verizon.net> wrote:
> On Thu, 9 Sep 2010 13:45:01 -0700 (PDT), "David E. Powell"
>

And of course the inevitable happened one day at Holloman AFB, when
someone filled a Thud's water tank with JP-4. Story goes that when
the pilot selected AB on takeoff, the tail of the jet exploded.

Details, anyone?

Kirk

Daryl Hunt

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Sep 9, 2010, 5:24:03 PM9/9/10
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That has to be a wives tail. Unless they backed a fuel truck up
to the plane and everyone was completely stupid that day, I don't
see how that could happen.


Ed Rasimus

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Sep 9, 2010, 5:56:02 PM9/9/10
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That's the way I read it as well. All modern jets use single point
refueling in which a high pressure nozzle is attached to a terminal
point and then all tanks are filled simultaneously. There is no hose
stuck into a wing with a gas cap.

The water tank was clearly placarded as well as being a reservoir for
demineralized water only. You didn't simply drag the garden hose over.
Water was not routinely used for peacetime operations either. It was
strictly a combat load option. A refueling, gas & go at Holloman
wouldn't have serviced water under most situations.

Since the normal operation of AB is dumping hundreds of pounds per
minute of JP4 into the tail pipe, it really wouldn' make any
difference if you dumped an extra couple of gallons in from the water
tank.

I'm betting this is one of those "I bet it must have happened..."
stories.

Daryl Hunt

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Sep 9, 2010, 6:25:21 PM9/9/10
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> strictly a combat load option. A refueling, gas& go at Holloman

> wouldn't have serviced water under most situations.

On the KC-135A it was standard as well as the early B-52. A fully
loaded A model 135 took every inch of the runway with water
injection.

See
http://cdn-www.airliners.net/aviation-photos/small/9/4/0/1656049.jpg

The caption is:58-0043 (cn 17788) Of the 133rd ARS/New Hamspshire
ANG, based at Pease AFB. Seen on hold at runway 29 while a dirty
'A' model KC-135 gets aloft covering the airfield in smoke. Last
noted in storage at 309th AMARG.

The Buff was downright impressive when it had the J-57 engines.
You would think it was dumping a lot of fuel smoke when it was
really the water injection making all that smoke.

Both AC used Water Injection pretty much all the time for takeoff
to get it's 13,000 lb thrust per engine.

Ron

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Sep 9, 2010, 10:37:44 PM9/9/10
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On Sep 9, 3:10 pm, "kirk.st...@gmail.com" <kirk.st...@gmail.com>
wrote:

I heard that same story from a former Holloman F-15 driver and posted
it a few years ago. Most here said it was an urban legend, but then
someone posted here that they were at Holloman at the time, and that
it did happen.

Dweezil Dwarftosser

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Sep 10, 2010, 12:19:12 AM9/10/10
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Ron said...

I can see how someone used to the 'progressive' afterburners
of later jets might think that (any) F-105 had exploded, if
they heard it, rather than saw it.
F-105 AB starts with an explosion, every time - and is near
instantaneous.

David E. Powell

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Sep 10, 2010, 12:26:26 AM9/10/10
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Maybe it was gasoline? Or one could inject it under circumstances that
were unusual where it was confined.

Or, the flame followed the fuel up into the tank, something unlikely
with water.

Roger Conroy

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Sep 10, 2010, 4:05:03 AM9/10/10
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"Daryl Hunt" <dh...@i70westnospam.com> wrote in message
news:r9dio.36979$rC7....@newsfe10.iad...
Water injection is not a feature of only military jets
The Boeing 747-SPs operated by South African Airways also had water
injection for take-off because their main hub (FAJS) is a "hot and high"
airport.
I don't know if it was a standard feature of all/most 747-SPs.


kirk....@gmail.com

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Sep 12, 2010, 10:51:37 PM9/12/10
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Not an old wives tale - I remember reading about it in the AF safety
magazine. Apparently, someone on the flightline confused the trailer
with the water for the AB with a similar trailer for drained JP-4
(Some jets would vent a lot of fuel as it heated up during the day -
the F-4 comes to mind - and hoses would be hooked up and the excess
drained into a small tank on a trailer).

Anyway, due to the mixup on the similar trailers, JP-4 was loaded
instead of water.

Result: Boom on takeoff.

Safety aspect was of course to make sure the tanks for water and the
tanks for JP-4 were easily distinguishable, not painted the same
color!

Kirk

JasiekS

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Sep 13, 2010, 10:11:10 AM9/13/10
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Uzytkownik <kirk....@gmail.com> napisal w wiadomosci
news:7c1f095d-7368-4baa...@i4g2000prf.googlegroups.com...

> Anyway, due to the mixup on the similar trailers, JP-4 was loaded
> instead of water.

> Result: Boom on takeoff.

> Safety aspect was of course to make sure the tanks for water and the
> tanks for JP-4 were easily distinguishable, not painted the same
> color!

I have nothing to add except a side view. I strongly doubt that both
water and JP-4 hoses had the same fittings/valves/etc. There's a good
design practice (born in the USA AFAIK) that any junction should be made
such that wrong mating would be impossible. My side view looks like
urban legend.

--
JasiekS
Warsaw, Poland

kirk....@gmail.com

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Sep 13, 2010, 10:27:25 AM9/13/10
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On Sep 13, 7:11 am, "JasiekS" <jasieks.no.s...@please.poczta.onet.pl>
wrote:
> Uzytkownik <kirk.st...@gmail.com> napisal w wiadomoscinews:7c1f095d-7368-4baa...@i4g2000prf.googlegroups.com...

Just because it shouldn't be done doesn't mean it hasn't!

Kirk

Ed Rasimus

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Sep 13, 2010, 11:16:58 AM9/13/10
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OK, you've introduced the safety bulletin aspect which indicated that
the incident happened. While the tank possibly could have been
serviced with the surplus fuel bowser which would be an over-the-wing
style nozzle, how do we get an explosion when you dump some JP-4 (a
relatively small amount) into an A/B can which already contains a
hydrant like flow of JP-4 from the A/B fuel control?

Typical operations did not use water injection. It was strictly for
max gross combat load-outs. The water system was inter-locked in
several ways to safeguard the unstressed water tank which wouldn't
tolerate flight g-loads when loaded. The main interlock was to the
cockpit pressurization system. Normal check list procedure for before
takeoff was to close the canopy, check the roller over the hooks for
security, then move the RAM/Dump/Pressurization control to A/C and
pressurize. When that was done any water (or fuel) would be dumped
automatically on the ramp. It resembled a cow on a flat rock and
happened occasionally with new guys making their first water T/O at
Korat.

If the intent was a water T/O, then a large toggle switch was
activated ONLY after brake release, throttle outboard, positive burner
light (unmistakeable!). Without a burner light, water would not be
injected.

After burner out, the toggle switch was moved to the "dump" position
and cockpit pressurization was chosen.

In other words, normal ops stateside, particularly from a transient
base, would not have used water. If this were a deployed exercise with
heavyweight takeoffs required, there would have been regular F-105
ground maintenance.

I'm still saying it is a very improbable, if not impossible,
occurrence.

Jeff Crowell

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Sep 13, 2010, 11:47:26 AM9/13/10
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kirk....@gmail.com wrote:
> Just because it shouldn't be done doesn't mean it hasn't!

Heh. Never underestimate the ability of a motivated fool!

Jeff
--
Never try to win an emotional argument with facts.

Daryl Hunt

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Sep 13, 2010, 11:52:07 AM9/13/10
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I agree with you on that one. But, careful, you are sounding too
close to the "Mythbusters" :)


ob99...@gmail.com

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Oct 13, 2014, 7:54:56 AM10/13/14
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I don't know why I thougth of this today and googled it but the brain works in strange ways.

I was in POL at the time (1975-77) the 105 was (mis)serviced at Holloman. Here is how it happened: Airman M was sent out to hook up to the demin water trailer and tow it out to the aircraft and service with water. Dispatcher failed to inform M that the trailer was in the garage overnight to prevent the water from freezing in the pump. M went to the parking area where several trailers of the same type were normally parked and failing to read the marking on the CONTAMINATED FUEL trailer of the same type as the water trailer, attempted to hook up. He had difficulties with the tow coupling and called for his supervisor to assist. Supervisor, aware of the call for demin water for the 105, assisted with the hook up also failing to note the marking on the trailer with the wrong product. It gets worse. M arrived at the transient pad and the ground crew assisted with the loading of the product on the 105. M and crew chief both signed on the delivery form that they had visually confirmed the markings on the container (and of course, they had not). Nobody seemed to notice the odor of fuel coming from the water tank either. (BTW, the nozzles for both trailers were idendtical overwing type nozzles). M left the area and parked the trailer back on its spot unaware of his error until the kimchee hit the fan. Commencing his takeoff roll, the pilot opened the "water" and got contaminated fuel. The rear end went up in a ball of fire but the aircrew made it out alive jumping out of the cockpit and running for their lives. I know because I not only worked with M but I was the guy who had to put the water on the 105 almost a year later when the bird had been repaired and was ready to fly out. There was more brass tasting my water than you could shake a stick at. I will always remember this event. I've run into ex-AF pilots years later who remember seeing the bulletin and wondering how it could ever have happened. BTW, Airman M got a suspended demotion one grade but lost pay and had the reprimand on his record. M's lawyer protected him from a worse fate by harping on the number of people involved and the lack of proper management at POL. The AF was unwilling to hang everyone, so the NCOIC and OIC were transferred out and had the thing on their records. Those are the facts and yes, it did happen.

R.

Peter Stickney

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Oct 22, 2014, 12:50:04 AM10/22/14
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ob99...@gmail.com wrote:

> On Thursday, September 9, 2010 4:45:01 PM UTC-4, David E. Powell wrote:
>> Looking at the "water cooled turbine" stuff in the "US Jet Engine
>> 1940" thread, it got me thinking:
>>
>> Given that water that flashes to steam can really expand, was a water,
>> water-glycol or water-alcohol mix ever considered for an afterburner?
>> Heat up the nozzles in the jet exhaust pipe, and then inject water/
>> glycol as needed? Instead of fuel, good old water gets used. Steam
>> trail should be huge, but otherwise it may be doable, though the
>> pressures generated would be pretty huge.

Not in the exhaust, but before the combustors, either before or after the
compressor. This increases mass flow and lowers the temperature, allowing
more energy to be put in by burning more fuel.
It was common on straight turbojets from the late '40s through the '50s.
I think the last jets to use in in regular service were the B-52G, KC-135A,
and the AV-8B Harrier. (Steam Jets! From the Days When Man Could Burn
Water!)
>
> I don't know why I thougth of this today and googled it but the brain
> works in strange ways.
<Snip - F-105's water tank gets filled with fuel - Bad Things Happen >

Apropos of this, I was reading an article by one of the Navy's early jet
aviators- He was flying a TV-1 (Navy F-80C, which had water injection,
although they didn't use it much) The Plane Captain told him that he'd
serviced the water tank, (And thus had injection available.) As was not at
all uncommon in late '40s/Early '50s Southern California, he got bounced by
rival fighters, and they ratraced for a while. While he contemplated
triggering the water, he didn't need to, and returned to base with the tank
full. Good thing - The Plane Captain had serviced the tank with AVGAS. The
consequences of dumping 60 gallons of 115/145 octane into the engine would
have been catastrophic.
--
Pete Stickney
From the foothills of the Florida Alps

dump...@hotmail.com

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Oct 22, 2014, 11:36:51 AM10/22/14
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