Canberra startup question

Great info chaps, thank you……….

The starter cartridges, via the starter unit in the pointy bit on the front of the engine cause the turbine to run up to speed for ignition. The early Canberras had two diagonally opposed vents for the starter gasses and the B.6 in your picture had three. The B.2 had one cartridge per engine (single breech) and the B.6 had three per engine (triple breech), so two spares after a start.

John

As far as I know, the cartridge is just a compressed air source – the small explosion causes the engine to rotate and a fair speed allowing for engine start…

The Canberra had a cartridge starter. 780 grams of cordite if I remember correctly. It makes a fair noise when it goes off.

To expand slightly (I like talking about Canberra’s!) the starter unit bolted to the front of the engine is essentially a turbocharger – that is it it converts a high volume of gas expelled by the electrically fired cartridge into high pressure gas via the small turbine in the starter, which is connected to the main shaft of the engine thus spinning it up to what is called “self sustaining” speed in a relatively short space of time. That used high pressure gas is then expelled from the starter, producing the plumes of smoke you see in your DVD.

Once the engine is at this self sustaining speed, the fuel being sprayed into the combution chambers is ignited by “cracker boxes” (High Energy Igniton Unit which is a glorified coil and spark plug arrangement!) and off she goes!

This is why you always hear a (cartiridge start) Canberra engine appear to slow down before it speeds up on startup – there is a small time delay between the starter spooling up and the fuel igniting.

Boring Canberra lecture over!

It should be explained aswel, that the three plumes of smoke that you see are from the same cartridge as it expels the waste from the charge through three exhaust outlets, not all three cartridges letting go simultaneously!!

Some engines require two cartridges for a cold start, one to churn the motor over and another to get it to sustaining and ingnition speed, the press button starter switches often having a clockwork timer mechanism built in to prevent accidental firing of carts too close to each other.

Far from boring Tim…… it’s what forums are all about – sharing the knowledge with those who ask the questions 😀

I can remember reading Robert Mikesh’s book about the Martin B-57.

IIRC, he mentions that the USAF Canberra crews always started the engine that exhausted AWAY from the open clamshell canopy first – then closed the canopy and started the other engine – otherwise the exhaust gases fired straight into the cockpit. 😮

Can’t remember which side was first though – but looking at that first photo, it was probably starboard.

Ken

Far from boring Tim…… it’s what forums are all about – sharing the knowledge with those who ask the questions

Thanks chaps, thanks for sharing your knowledge…..;)

Cartridge starting reminds me of an incident at Wattisham when the Hunters were new there. Sorry if I am treading on Canberra peoples toes but.

The Hunter had a cartridge start system with one or two spare cartridges in case of a problem, these were rotated into place as required.

Anyway, Hunter being started one day, first cartridge didn’t work, so No.2 rotated into place. This fired OK, but also set off No.1, which faced directly at a fuel tank. Said tank was holed and set on fire. Fire section very smartly covered the front of the aircraft in foam and contained the fire. WingCo Tech rushed to scene as fast as his little legs would carry him, determined to find the cause of the fire. He instructed the fire chiefy, a very wise and wily old NCO, to hose off the foam so that WingCo Tech could solve the mystery. Chiefy said “But sir I wouldn’t do that because…” but was cut short. “Flight Sergeant, do as I say!”

Hunter therefore became Cat 5 in resultant blaze. WingCo Tech not a happy bunny, fire crew hardly able to contain themselves.

As a side question, do they still make these carts or are we running on thousands of extant supplies??

It should be explained aswel, that the three plumes of smoke that you see are from the same cartridge as it expels the waste from the charge through three exhaust outlets, not all three cartridges letting go simultaneously!!

Some engines require two cartridges for a cold start, one to churn the motor over and another to get it to sustaining and ingnition speed, the press button starter switches often having a clockwork timer mechanism built in to prevent accidental firing of carts too close to each other.

Normal procedure is start port engine first, if that fails to reach self sustaining speed, 1100RPM, or a rise in JPT above 630C then shut down immediately, HP **** and master start off. When the engine has stopped turning and the starter button has re set a further start can be attempted. There are several causes for starter failure but a cold cartridge is often the cause and Canberra squadron crew rooms in the winter usually had starter carts sitting on radiators to get them warm, long before the advent of Elf n’ safety!

Is there a shelf life on them?

Will there be a day when engines will not be started due to a lack of carts?

Baz

As a side question, do they still make these carts or are we running on thousands of extant supplies??

Not that I am aware of

There have been a number of stories of companies who could refill spent cartridges for us operators, though I struggle to believe that they actually could as there is a lot more to it that just filling the cart up with cordite. Aside from that, we on WT333 run on a limited stock of surplus cartridges.

Every bang counts, so we do all we can to ensure a successful start every time!

Istr that the rhodesians developed an air start system for their canberras…

Is there a shelf life on them?

Will there be a day when engines will not be started due to a lack of carts?

Baz

Well there’s always the option of converting to electric start, or even air start as we are experimenting with our Hunter engine, which is arguably safer as it is easier to control as once you have fired the cartridge you are commited.

Tom