Shackleton fuel?

water meth

Camlobe,thanks for that great explanation!! I have experienced the kick in the pants sensation of water meth on more than one occasion!Real Shacks didnt need jets!!Are you ex coastal?

Slightly off the subject,but speaking of Shacks,a friend once took me to see a Shack in the Thetford area.It was just the fuselage cut into sections but fully fitted and stored in a barn,there were also two lightnings outside !! where is it now i wonder ?

Bi-fuel Shackletons

WL 745 is quite correct in mentioning the Shack had Water-Methanol injection to supplement ‘normal’ AVGAS, and the controlling switch was installed on the Flight Engineers panel.

The mighty Shack wasn’t unique in being equipped with Water-Meth, the Fokker F27 and the AW Argosy (second version) benefited from the installation of Rolls-Royce Dart engines that were similarly assisted. (My first four-engined ground-run was one of the Argosy’s at Halton – the one with working hydraulics and Water-Meth – eye-opening torque figures).

For those interested, the Shack installation was two 26 gallon tanks mounted in the outboard nacelles, each tank supplying the two engines on their respective wings. The engines were set up to deliver between 18 and 22 pints per minute of Water-Methanol (in a 60-40 mix, 60% de-minerialised water and 40% AL24 Methanol). This would give a theoretical maximum of four and three-quarter minutes, although it rarely exceeded two minutes of use.

The switch to engage the Water-Methanol pumps was ganged to the High-Gear switch for the supercharger, thereby preventing inadvertant use of High-Gear without Water-Methanol above 69″ Hg (Mercury) boost. The boost pressure sensing switches were mounted in the starboard side of the nose.

To give an appreciation of the difference Water-Methanol made to the Shackleton, Take-Off in Low-Gear with the throttle lever to the ‘Gate’ gave 67″ Hg boost (18 pounds of boost over and above atmospheric pressure), resulting in the production of 1960 HP at sea level, and 1990 Hp at full-throttle-height of 2000 ft.

Take-Off in High-Gear with the throttle lever through the ‘Gate’ and Water-Methanol injected gave 2450 Hp at sea level, and 2490 at full-throttle-height of 3000 ft.

So, the overall difference was approximately 8000 Horsepower available for a low-Gear take-off, or approximately 10,000 Horsepower available for a high-Gear take-off. What is another 2000 Hp between friends?

Although these full-throttle-height figures may seem low altitude, bear in mind the Rolls-Royce Griffons (Mk 57, 57A and 58) installed on the Shackletons were purpose-designed as low altitude engines.

As an aside, fuel consumption in Low-Gear at full throttle was 187 gallons per hour. In High-Gear at full throttle, this was reduced to 178 gallons per hour.

Why, you may well ask, was the fuel consumption reduced when the engine was required to produce more power?

Well, Water-Methanol served two purposes. The first and most important reason was as to cool the temperature of the heavily boosted charge at 25 psi over and above atmospheric pressure (i.e. 81″Hg in Shack-speak). The second was to supply fuel. As the Water-Methanol was injected into the eye of the supercharger, the water vapourised and (remembering latent heat of vapourisation) reduced the temperature of the charge from over 100 degrees C to 50 degrees C, thereby preventing detonation. The Methanol, which is a fuel, was then consumed. If the AVGAS fuel injector didn’t lean out the AVGAS, overfueling would have resulted. As a bonus, the Methanol also acted as an anti-freeze for the water. A real win-win situation.

P.S. all the above figures are from an aging memory, therefore my apologies for any inaccuracies.

camlobe

As promised…
After looking through 5 books on the B-36, I found no mention of special tanks for JP-4.

Thanks for looking, I’m certainly not under any impression that the B-36 used AVTUR for the jets, my point was that the engines used were ‘proper’ jet engines with throttle controls etc. When considered over the restricted and set RPM unique Vipers of the Shackleton, I wondered how the J-47s fared with AVGAS, ie you don’t here of blade failures or lead fouling etc with them.
All the witnesses I know who have seen B-36s flying overhead mention the unique piston and jet noise, which would indicate the jets were used sometimes in transit, or this a case of expectation!

Having seen Newark’s Hastings picture I thought I would share with you the Chinagraph pencil message written on the Engineers panel in their Shackleton WR977, which perhaps typifies many peoples view of the type and reads “Shacks are wonderful, in their own way”.

……/Didnt the Hastings have throttles at the eng position?

Yep this is the Newark example

Just a little aside vis a vis US and UK jet fuel -until the late 70’s the US jet fuel was JP4 (AVTAG) which was historically petroleum based (smell similar to 4 star) and good for cold climate operation – ie less tendancy to ‘wax up’.
Historically UK jet fuel is kerosene (AVTUR)-much less volatile/higher flash point but with tendancy to ‘wax’ in low temps hence the addition of FSII (icing inhibitor) to keep it liquid.I was surprised to find recently that civil jet fuel does not have FSII… cost ??? but surely cheaper than a 777 :diablo:

cheers baz

Shack fuel

Dont forget the Griffons had Water Methanol injection also and that was an impressive kick in the pants!This if I remember correctly was swithced on from the Engineers panel and only 30 seconds was allowed.Anon,Both Captain and second pilot had throttles,nothing to do with the engineer.Didnt the Hastings have throttles at the eng position?

As promised…
After looking through 5 books on the B-36, I found no mention of special tanks for JP-4. One did note that any engine could feel from any tank, so I suppose it was possible that by keeping the flight engineer very busy all 4 jets could feed from the same engine, but again there was no mention of that being done. Another item that seems to indicate that the jets used the same fuel is the fact that all existing A & B models were retrofitted with jets. Adding a second fuel system without redoing the entire wing would have been difficult and costly.

BTW: the jets were only operated at take off and at times when extra “dash” speed was required. Special shutters were fitted on the front of the jet nacelles to blank them off during cruise (though they were left slowly windmilling to prevent freezing at altitude). The jets were credited with raising the speed by about 60 mph and probably equally importantly, increasing TO weight.

The piston engines had a TBO of 300 hours (though some went much more) so again I’ll guess that having a slightly reduced TBO on the J-47 because of AVGAS use was no big deal.

Shack throttles

Yeah,

Shack pilots may have had their own throttles but they got a rap over the knuckles from the flight engineer if they went near them didn’t they?!

Anon.

No throttles for the Pilots…..even the Griffons? 😮

Don’t panic, the drivers had throttles for the Griffons.:D

Belfast Underpowered?

I have to confess I’m basing my impression on the Farnborough 1970 show where I was legging it up and down the crowd line trying to guess the lift-off point of the demonstrating aircraft for dynamic photos….the Belfast seemed stuck to the ground!

and apologies to the
Shackleton thread-starter! 🙂

The problem with the Belfast was’nt lack of power but high drag from the back end.

Booster jet engines

Was the Shackleton the only British prop type to have booster jet engines ( a performance option so much favoured by the U.S.)? Some British transports might have benefited from it e.g. the Belfast?

The AVGAS burnt the compressor blades.

All controlled of course by the Flt Eng, no throttles for the “drivers”.

AVGAS burnt the turbine blades surely? :confused:

No throttles for the Pilots…..even the Griffons? 😮

About the aux jets running on AVGAS…

I doubt if SAC worried about overhaul costs and TBO. If the jets were for aux. only, it might take a good while to hit even a reduced overhaul time. I’m guessing the hourly cost for operating a B-36 was so horrific, that a few dollars more for a reduced TBO for early (cheap) jets was the least of their worries. Rather like buying tires.

BTW: I did check and in the KC-97, the refueling tanks were seperate from the tankers supply, so it ran happily on AVGAS while pumping JP-4 to receivers.

I’ll check in my B-36 book collection tonight and see if I can find an answer. on the 36 setup.

To go a bit OT:eek: I seem to remember from my ground school on the Twin Otter, that the PT-6 turbo prop engines will run quite happily on AVGAS and it is certified for use in that engine as a “get me home” last resort. IIRC there was a limitation of 150 hours of running time on AVGAS during the engine live.

He is right Sgt, hence restricted use, blade failure, and fouling. The other thread on this subject is well detailed and is worth searching out.
When I was a kid I always thought that the tip tanks that were unique to the MR.3 held the Viper Avtur fuel, then I realised that the MR.3 was around for about 6-8 yrs before the Viper mods!
As Peter says the Viper fit wasn’t a Phase III update, but the conversions were carried out during a similar time period, and some were made at the same time.

We had a chap who was involved with the development work in fitting the vipers on shacks give a lecture at a small group I used to belong to (sorry I can’t remember his name). He told us that originally they were going to use separate fuels, avgas for the griffons and avtur (I think, not too sure on technical things) for the vipers. They realised that using different fuels would probably lead to problems with the wrong fuel in the wrong tanks and so decided avgas for everything. This was not as easy as has been suggested. The viper fuel (avtur?) was used as a lubricant on some of the bearings before going through to be burnt. Avgas was too thin and so unsuitable as a lubricant and significant changes had to be made to the vipers before they were fitted. This was discovered when the first few vipers had been fitted and were wrecked in no time. As I said I’m not sure of all the technicallities and it may be complete rubbish but he seemed to know what he was talking about and I had no reason to doubt him.

I seem to remember solid-fuel booster rockets too.
I have never seen any aircraft using two fuels for boost-jet-engines and their main piston ones. The sole reason for the Jet engines is extra take-off power to shorten the take-off distance when fully loaded with fuel and bombs.

The “proper” name for these where JATO (Jet Assisted Take Off).

Aircraft are never designed to carry death weight unless it is absolutely needed to be used carrying out their role. In that case it is no death weight anymore isn’t it?

Besides a store, extra piping is needed along with pumps, indicators, filler caps etc. It is just not aviation wise to make a dual fuel aircraft.

Martijn