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RAAF CAC Sabre. Finished. Thankyou Brick!

ericg

By ericg
in Works in Progress

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  • 2 weeks later...
Brick

Brick

Posted
Posted

Good to see you are back at the forge, Eric.

 
Firstly, one small thing:  I noticed that, in your Rumpler build log, you mention that you encountered a vexing problem with the lozenge decals, as a result of which you spat the dummy and spent the next two hours in the foetal position underneath your workbench, refusing to come out.  So, may I ask a favour?  Next time you do that, could you get your better half to take a photo and send it to me?  I mean, I'd be prepared to pay good money to see that :)
 
For the folks following this build, I regret to say that the time has come for more reminiscing about my Avon Sabre days in South East Asia.  Yes, I can see the eye-rolls and hear the moans of dread at the prospect of being bored out of your minds by a fighter jock yet again; but, hey, I'm an old guy, so indulge me just a little.
 
On 17th October 1963, I was tasked to ferry a Sabre from Ubon in Eastern Thailand back to Butterworth in Malaysia for a major servicing.  With full internal and external (167 gallon) tanks, I took off on Runway 23, only to get a PV Ram failure just after the gear and flaps had come up.  The main symptom of PV Ram failure is pretty simple: you experience a sudden and rather annoying loss of thrust.  Quite a significant loss of thrust, in point of fact.
 
The PV Ram operates the swirl vanes on the Rolls Royce Avon, which are located just in front of the first stage of compressor blades.  It is operated by fuel pressure, causing the vanes to start opening, as I recall, at about 5300 RPM and finish opening at about 8000 RPM.  When the PV RAM fails at high RPM, the swirl vanes close, starving the engine of air.  Apart from the embarrassing loss of thrust, the other symptoms are pretty straight forward:  RPM stays the same, but Jet Pipe Temperature (JPT) almost immediately drops to about half what it should be.  There is no other failure that results in those symptoms, so I knew immediately exactly what had conspired to get my day off to a less than optimal start.
 
Take a look at that ejection seat of Eric's.  The full-sized one is vastly more comfortable than the Martin Baker seats in the Vampire Mk 35s I did my Wings training on, but also vastly less capable.  It was a pretty primitive device, even for the early sixties, and was not even close to zero/zero; in fact the minimum safe ejection altitude above ground was 1000 feet.  In any event, an ejection would have been out of the question with the built-up area of Ubon right in front of me.  That area also prevented me from immediately jettisoning the external tanks, which I desperately wanted to do, given that I just didn't know at that point whether I would be able to keep the bird airborne.  Everything depended on where I was on the drag curve at the speed I was at, so all I could do was nose-over and level the bird out right on the rooftops, keeping my eyes glued to the airspeed indicator, willing it to hold steady or perhaps slowly increase, and knowing that it could just as likely slowly decrease. I thought that, if I could just keep the bird airborne until I cleared the built-up area, I might be able to belly it in, if necessary, after I passed the Ubon jail and the Mun rivulet.  
 
I passed the jail below the level of the watchtowers (see photograph), and can still remember seeing the guard in the south eastern tower looking across at me with what was no doubt keen interest as I sailed past at pretty much the same speed I had when the failure occurred.  Good, I thought, at least I'm not going to make a fiery urban spectacle of myself today, even if I have to eventually belly this thing in to a rice paddy.
 
ubon%20map.jpg
 
Having made it to the edge of Ubon, I was about to jettison the tanks when I observed the airspeed increasing, albeit agonizingly slowly.  So I just held the bird on the deck for another couple of miles to see what speed I might be able to get up to before starting a very, very gradual climb and a very, very gentle turnback to the airfield.  Having decided what I was going to do, I called the tower controller to get my Flight Commander into the tower so that I could explain what had happened, what I intended to do, and hopefully get his blessing for that plan.  My Flight Commander agreed with my intentions, so I retained the external tanks (I was determined to recover the bird intact if I could) and orbited the airfield for about 50 minutes to burn out the fuel, always remaining in a position from which I could execute a forced landing if the engine finally gave up the ghost.  Eventually, when I was down to a safe weight, I landed the bird off a precautionary forced landing pattern.  
 
Next day, after the troops had replaced the PV Ram, I flew the bird back to Butterworth.  A glorious 2 1/2 hour flight out to Korat and then down over the Gulf of Siam in amongst the towering tropical cumulo-nimbus at 45,000 feet.
 
The reality was that, if the PV RAM had failed just a few seconds earlier, I would have spread myself and a jet laden with fuel all over beautiful downtown Ubon, no doubt killing and maiming a good many people.  But the curious thing is that the incident never affected me in the slightest.  I slept soundly on the night after the incident with not a worry in the world.  A couple of days later, I thought that this thing would catch up with me sooner or later, but it never did.  I guess that was because, when you're young, you not only think you're invulnerable, you actually know you are - even in the face of incontrovertible evidence to the contrary.
 
Nope, it didn't concern me at all back then.  But these days I very occasionally think back on the time I came, literally, within 10 or so seconds of buying the farm and almost certainly killing and maiming a lot of innocent people on the ground, and it makes me think a bit.  What would my last thoughts have been when I realised that I was about to clobber that heavily populated area?  I mean, there are few things worse than being faced with a really dicey situation and knowing that you can do nothing - absolutely nothing - but just sit there and await your fate.
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