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Old 10-01-2012, 11:35 PM
*Buzzsaw* *Buzzsaw* is offline
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Join Date: Oct 2007
Location: Vancouver Canada
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Default Cold Start prior to flight: Never done, all engines should be pre-warmed

Salute

Once again the British side is having to deal with the nonsense of not being able to start their engines, or having to wait ten minutes while cranking them over.

The fact is, the RAF had a very detailed set of operational procedures in place which determined how quickly their aircraft could be put into the air. These procedures were set up to take advantage of the early warning radar system they had in place. After all, why spend Millions of pounds on creating a radar system which gives you a head start and then having that advantage cancelled because your planes are stuck on the ground warming up their engines....

Squadrons were graded according to their ability to get into the air.

1) 'Stood down', which meant they were not expected to fly. Pilots were released to return to their quarters.
2) At a certain time 'Availability', ie. typically '30 minutes availability', which was the intermediate stage between Stood down and 'At Readiness'. Pilots were expected to be in the mess, closeby and available.
3) 'At Readiness', which meant they were ready to scramble immediately. Pilots were often expected to wait in the cockpit, but more often on the field in dispersal. In some case, only a single flight would be 'At Readiness', if the Squadron was primarily tasked with intercepting single reconnaissance planes instead of major raids, but normally this would be the entire Squadron.

Squadrons would be moved from 'Availability' to 'At Readiness' prior to being scrambled. In the case of 11 Group Squadrons, all were typically brought to 'At Readiness' at dawn.

ALL Hurricane and Spitfires were started up and pre-warmed by their ground crews prior to the Squadron being declared 'At Readiness'. This was to allow an instant scramble, there was no future in having to sit on the ground warming up the engine of your Hurricane or Spitfire while the enemy formation approached, perhaps to bomb your field.

As an example, here is the detailed procedure for coming to 'At Readiness' as recounted by Geoffrey Wellums from his book 'FIRST LIGHT', which is an account of his experience during the Battle of Britain.

It is not only a good summary of the activities which happened at dawn to ready the aircraft, but also a great piece of writing from a great book:

Quote:
It is first light and still and rather beautiful; the birth of a new day. Reveries are suddenly and rudely broken. A raised voice comes from somewhere in the gloom, curt and to the point.

'OK. Clear? Contact?

The engagement of a starter pinion and the clank of a reduction gear as in a not far distant dispersal pen an airscrew turns, flicking over. The engine fires twice but does not pick up, as if loath to shatter the serenity of the moment. Then, giving up the unequal task of combating the primer pump and the starter trolley, it explodes into life with a spurt of flame from the exhaust stubbs. The peace and quiet is finished, the silence no more, the day has begun and now to business.

One after the other, Spitfires are starting up. The fitters warm up their engines. Twelve Merlins, all at 1200 revs or thereabouts. The power of the moment is awe inspiring. The still morning air reverberates with the sound of harnessed energy. Slipstreams flatten the grass behind the quivering aircraft. In its way it is exciting, wonderful and not without a certain beauty. It is also tragic; which of us is going to be killed this day?

Dispersal pen and my Spitfire. I pause and look at her. A long shapely nose, not exactly arrogant but, neverless, daring anyone to take a swing at it. Lines beautifully proportioned, the aircraft sitting there, engine turning easily and smoothly with subdued power. The slipstream blows the moisture over the the top of the wings in thin streamlets. Flashes of blue flame from the exhausts are easily seen in the half light, an occasional backfire and the whole airplane trembling like a thoroughbred at the start of the Derby.

The engine note increases as my fitter opens up the Merlin to zero boost whilst the rigger stands with his hand on the wingtip, watching expectantly. I think to myself, "Don't open her up any more you twit, or the tail will lift and the whole shooting match will end up on its nose." The engine note changes fractionally as the magnetos are tested. The fitter, intent on his instruments, red cockpit lights reflecting on his face. Sounds OK, not problems there at all. Throttle back, mag check again at 1500 revs by the sound of it and then throttle right closed, engine idling, smoke from the exhausts, cutout pulled and the engine splutters to a stop. Peace again.

Bevington, the fitter, looks up from the cockpit and gives me the thumbs up. He levers himself out on the wing and jumps to the ground. I walk forward and hang my parachute on the port wing for a quick getaway; you can easily put it on whilst the engine is being started, saves a lot of time.

Now to the cockpit. Up on to the wing and step in. I hang my helmet on the stick and plug in the R/T led and oxygen tube. At the same time, I check the bottle contents: full. Fuel? Press the fuel gauge button, reads full also. Now Brake pressure. OK, that's fine. Trim? Lets adjust it now and then its done with. Full rudder bias to help with the swing on takeoff, elevators one degree nose heavy, that's good. Airscrew, full fine pitch. That's about it, then, ready to scramble when the time comes. Bound to come sometime. It will be a miracle if we get through to midday without one.

I climb out of the cockpit and my fitter and rigger are waiting, as always. What stalwarts they are, both utterly loyal to 'their' pilot, dedicated and uncomplaining. They are both smiling and friendly.

'Twenty five drop on both mags sir. We found that oil leak last night. Nothing to worry about and in any case we reckon we've cured it.'
'Splendid; so we're at readiness, are we?'
'On the top line, sir.'
'Good men, see you both later, no doubt.'
The engine would be warmed up again later during the day if required, never would temperatures be allowed to drop to the point a difficult start could happen.

Although they didn't have the same requirement to react instantly to incursions, the Luftwaffe had a similar procedure in effect prior to takeoff, that being the ground crews pre-warming their pilot's aircraft engine so it was ready for takeoff.

All aircraft should start with pre-warmed engines.

Last edited by *Buzzsaw*; 10-02-2012 at 12:00 AM.
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