|
Vulcan Limit
Reading “the Vulcan Story” by Tim Laming and surprised to see under altitude limitations “There is no height restrictions on the aircraft because of airframe limitations. However, the maximum operating altitude is limited by the oxygen equipment as follows: ……..”
It then tabulates the various combinations with 56,000 feet cabin altitude being the maximum. With a maximum pressurisation differential of 9 PSI surely the bomber boys would have bragging rights over the Lightning altitude attempts on a recent thread. What was she capable of? I’m sure in true military fashion some one must have attempted the official limit plus a bit. |
Re: Vulcan Limit
There are a number of aircraft that are altitude limited by cabin/oxygen. The limits are based on the depressurised case. This is, of course, more likely in military aircraft that may suffer battle damage. It is not always practical to wear full pressure suits!
|
Re: Vulcan Limit
The Vulcan was certainly capable of such heights when light, the problems being:
1. There were 2 types of oxygen regulator. The Mk17 could not deliver the required overpressure at such heights, being capable of a maximum of 30mm Hg overpressure. However, although the Mk21 could deliver up to 50mm Hg overpressure, it was necessary to wear a counterpressure pressure jerkin and anti 'g' suit in order for the crew to cope with such high levels of pressure breathing. 2. In the event of loss of the cockpit canopy, aerodynamic suck could reduce cabin altitude by 5000 ft, so to lose the canopy at 50000ft gave a cabin altitude of 55000ft. 3. The aeroplane was so aerodynamically clean, that it took too long to descend from high level to a height at which the Mk17 regulator would cope. So, if you decided to fly at 56000ft and were to lose the canopy, the time of useful consciousness would be less than the time it would take to descend to a safe level..... Did people bust the limit? I've been up to above FL510 with one captain who decided that the chance of losing the canopy or experiencing explosive decompression were infinitessimal. No-one had ever suffered either problem in the past. The aeroplane flew quite happily and we turned with 45 deg AoB watching a pair of F4s trying unsuccessfully to get a firing solution. |
Re: Vulcan Limit
I thought that the margin between cruise speed and stall above FL55 could have been a limiting factor? I'm sure there couldnt have been much latitude for error.
The Frightening was just that little bit quicker at altitude. |
Re: Vulcan Limit
Anyone heard of coffin corner?
|
Re: Vulcan Limit
I flew the PR9 and that too had a major problem losing height after any cabin pressure loss. We sometimes flew in the gear mentioned by Beagle plus the Taylor pressure helmet, a very uncomfortable bit of kit in the Middle East! At extreme altitude the problem really was turning - the outboard wing would get near to MCrit and the inboard wing would get near to stalling and control was marginal to say the least.
|
Re: Vulcan Limit
Aeronut and ionagh, the delta-wing Vulcan did not suffer from 'coffin corner'. There was no such thing as 'low speed buffet boundary' or a conventional stall - at high AoA the drag simply increased until level flight was no longer possible with maximum continuous thrust. The only aerodynamic limit was the release to service maximum permitted IMN of well over M0.9.
|
Re: Vulcan Limit
Just found that 61,500 was reached during test (4-3-1959) of the first production B2 (XH533). Still, what do you think she would have been capable of BEagle?
|
Re: Vulcan Limit
I still had 300fpm climb rate at FL550 going over a line of thunderstorms which lay between the Great Lakes and Florida en route Offutt to Goose. The ac would probably reach in the order of FL600 before the roc reduced to 100fpm [at a guess].
It was only 27 Sqn who wore the special pressure kit whilst on spec ops, although quite a few ac were fitted with the Mk21 regulator. |
Re: Vulcan Limit
Beags memory has slipped slightly, the Mk 21 delivered 70 mm pressure. We only switched to the low altitude Mk 17 after 1965-66 when our high level lkit was withdrawn.
The NBC Calc 3A had height range of 17200-60000 feet which limited our ability to conduct computed bomb runs below 18000 feet. About 1968 the Mk 1 Calc 3s were retrofitted to the Mk 2 Vulcan which gave us the same height range for ballistic computation at 7200-50000. This meant we could now do 2G attacks (popup to 8000 feet). By this time we were doing laydown attacks and did not need to use the Calc 3 for ballistic calculation. FJJP, I concur with your height, we got 555 over Glasgow at about 120k on an air test and gave up with a ROC of about 300-500. I have just done some ODM work and was surprised to find the height over target would be only 530-540. Once the 21000 lb load had gone we could continue to cruise climb to 560. Aerodynamic suck was not an issue in the mid 60s and was only 'invented' after the switch to the Mk 17 regulator and the suggestion that we limit our upper level to 450. The Lightning, with the 21F regulator and the Taylor helmet could go to 660. It wasn't the aerodynamic suck that worried me but the 45000 feet free fall if we had to bail out. |
Re: Vulcan Limit
IIRC there was an issue with the Mk21 regulator delivery pressure which limited alt to 470 without pressure clothing. Paradoxically, the lower delivery pressure of the Mk17 allowed an alt. limit of 490. The definitive answer is no doubt in the loft!
YS |
Re: Vulcan Limit
So what did 27 sqn do that meant they had to go that high?
|
Re: Vulcan Limit
You do not need to know.
|
Re: Vulcan Limit
Secret trials of:
nosebleed remedies! CG |
Re: Vulcan Limit
Good old "Captain Cold War" to the rescue again;)
Defending our secrets from the Russian hordes:ok: |
Re: Vulcan Limit
Hunting for the foxes
|
Re: Vulcan Limit
The Cold War may be over, but certain classified operational capabilities may still be required.
Such as sowing chemtrails to subjugate the lower orders. Oops, b*gger. Black Omega alert! |
Re: Vulcan Limit
I have a 25 year old Black Omega, and it still keeps really good time.
CG |
Re: Vulcan Limit
"So what did 27 sqn do that meant they had to go that high?"
He thinks that you don't need to know. "The Cold War may be over, but certain classified operational capabilities may still be required." He obviously doesn't know, or doesn't know that 27's role and secondary role have been described in detail in a number of publications. Rather than provoking his angina it's obvious from the role and from the kit that these jets were sometimes seen carrying..... |
Re: Vulcan Limit
...were clearly chemtrail sowing devices.
The front bomb bay tank was isolated and filled with reagent Alfa. Reagent Bravo and the mixing device were installed in a standard bomb bay pannier. Dispensing devices were installed in the redundant 'window' hoppers. Allegedly. |
| All times are GMT. The time now is 08:10. |
Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.