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PR9 Engine start system

Printed From: Just Flight Forum
Category: Just Flight Products
Forum Name: English Electric Canberra PR.9
Forum Description: In-development area
URL: http://forum.justflight.com/forum_posts.asp?TID=21954
Printed Date: 18 Apr 2024 at 3:38pm


Topic: PR9 Engine start system
Posted By: Biggles2010
Subject: PR9 Engine start system
Date Posted: 14 Feb 2014 at 3:14pm
I have seen a few references to a cartridge start system in relation to the PR9. In fact the PR9 never had a cartridge start system.

The earlier PR3 and PR7 used cartridge starters which were fitted before flight with brass cartridges containing an explosive material.
The PR7 had a magazine which held 3 cartridges for each engine. If my memory is correct, the PR3 only had one cartridge per engine.

While the PR3 and PR7 were based on the original Canberra bomber airframe, the PR9 was a completely new variant, built by Short Brothers in Belfast. Only around 26 were built in total.

The PR9 engine starter used a highly volatile liquid called Avpin. This was discharged from a container in each engine into a starter unit where it was ignited. This generated high pressure gas to rotate the starter unit, and therefore the engine. The system allowed several starts to be made before needing a refill.

In the process excess gas and fumes were vented from the starter unit. The smell was unforgettable and very pungent. When breathed in, it would certainly clear the nasal passages.

As stated elsewhere XH134 was later modified to use an electrical starter unit. I suspect Avpin would be subject to all kinds of restrictions today.

John.


Replies:
Posted By: Martyn
Date Posted: 15 Feb 2014 at 11:10am
Just to clarify, our Canberra PR9 is based on XH134 which is back in the skies with 'Midair Squadron'. Therefore the cartridge start system is not used and is instead replaced with an electrical start system.

Martyn


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Martyn
Just Flight Ltd

Posted By: Biggles2010
Date Posted: 15 Feb 2014 at 4:15pm
Martyn

Firstly congratulations on producing such a realistic looking simulation of this aircraft. The graphics in the previews are setting a very high standard and difficult to distinguish from the real thing. And I write as someone with a couple of thousand hours on PR9s, including XH134, in the sixties and seventies.

I appreciate the Justflight PR9 is based on the current state of XH134.
My original post was really about the inaccurate references to the PR9 having previously had a cartridge start system, which you refer to again in your response.

The PR9 always had a liquid Avpin starting system unlike any other model of Canberra. No cartridges of any kind were involved. As you state, XH134 was then modified, on its acquisition by Midair Squadron, to an electrical starter system, most probably because of emissions controls and other restrictions affecting the use of Avpin now it is in civil operation.

Regardless of the above, it's great to see that XH134 will continue to fly and thank you Justflight for producing such a fine simulation. I'm just waiting for its release.

John

Posted By: Henk Schuitemaker
Date Posted: 21 Feb 2014 at 12:10pm
Several SOH members incl myself did get black cartridge smoke puffs upon engine start. This comes from the aircraft.cfg - startup = fx_canb_start entry.
 
The funny thing is the fx_canb_start.fx file is not included in the JF installer but it is used in the Flying Stations Canberra series, so I guess everyone who has those installed will see the black cartridge puffs.
The cure is simple, change the aircraft.cfg - startup = fx_canb_start entry like this:

[EFFECTS]
wake = fx_wake
water = fx_spray
dirt = fx_tchdrt
concrete = fx_sparks
touchdown = fx_tchdwn_m,1
startup = fx_dummy

Posted By: Wyton58Luqa39
Date Posted: 14 Apr 2014 at 1:04am
Avpin is a mono fuel that requires no oxygen to burn. Good for cleaning uniforms but alas it rots the stitches. Each engine avpin tank is good for 4 starts. Avpin burns with no visible flame - good in summer when Squadron ground crews wearing shorts and you set fire to a spoonfull on the ground just before they walked by. I remember in the early 1960's at Luqa on 39 Sqn I went to ground run a PR9 and instead of avpin a new Squadron engine guy topped up with Avtag. On pressing the start button flames shot down to ground and back up into the intake on stbd engine. Had finger on fire button but was not needed, on a separate incident when doin a ground run for a new generator balance check the engines where a 90% and 55% when the A/C jumped the chocks. Hydraulic pressing in cocpit was 2750 psi but only 300 psi at wheels - Chiefy thetold me to check other other 8/9 A/C before going home. Happy days - just thought you might be interested


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