deltapapa

Anyone know who the crew was? Dave Thomas & Mike Pollitt were spotted but no sign of Martin Withers or Al McDicken...


Left hand seat David Thomas
Right hand seat Iain Young MA test pilot
AEO Barry Masefield
4th seat Andy Marson

TEEEJ

Again, thanks for the heads-up, Dis Gruntled.

Cheers

TJ

Pontius Navigator

For its day the Compass System on the Mark 2 was state of the art but in a modern context is actually quite simple.

There are really two areas where there may be problems, neither usually difficult to fix. One is the MFS with its instruments, gyros etc, the other is the one of magnetism.

An MFS problem might be one of amplifiers or gyros but I would hazard a guess that it is neither as these are testable items and not ones that would only present problems during calibration.

Magnetism, OTOH, might be more likely and the throwaway about magnetic rivets actually quite likely. We had a Phantom where many of the canopy arch rivets round the standby compass were magnetic. The rivets had become mixed in the shed and were otherwise indistinguishable from the alloy ones.

I had a problem with the first swing on the Lancaster where the P10 would just not fix until a young engineering officer (he was older than me at the time) suggested a Sperry swing. See below.

The Vulcan has been sat on one heading for many years, years longer than it has ever sat before. In that process it will have acquired magnetism and this will need greater corrections than normal. The problems might be with the E2B in the cockpit or the Sperry flux valves in the wing tips. The former had a pair of bar magnets to be adjusted. The flux valves can be coarse aligned by a few degrees. More than that becomes more difficult. A coarse error should have been identified even before the aircraft left Brunty. Our Phantom problem was identified while it was still in the hangar.

Back to Sperry.

The first correction is the deviation on E-W / 2. So if the deviation on East is -2 and on West is -1 then the total error correction is -2 --1 /2 or minus 0.5 deg. Easy. Or maybe it was -2 and + 1 which would be -3/2 or minus 1.5.

The problem starts to arise with gross errors as we had in the Lancaster where the East was about -60 and the West was about -50. The formula produces a correction of just 5 degrees and the errors are hardly altered. The cause is quite simple - the aircraft system is not NEAR east or west so the correction is wholly wrong.

The answer was the Sperry swing. First make the aircraft comass on an easterly heading read EAST. Then move the aircraft to west and make the heading read WEST. After I had been given guidance (pun) the rest was easy.

For the Lancaster we just used a Landing Compass. For the Vulcan we used a Watts Datum. As a bomber it needed an accuracy of 0.1 deg. As a display aircraft it would not need to be better than a degree or so. Swings just take time. A day is nothing.

Linedog

No TomTom 500 then, huh???

Al R

Pontius,

I will get slagged off for crawling ever closer to my 1000 by you know who, but thanks for an interesting post. Are you saying that standing still for so long has caused the compass to be unable to shed, if you like, some kind of built in memory?

Is not an retro fit commercial option suitable? Something simply bought off the shelf and put in?

Cheers.

PS:

TJ: Cheers for your reply about RAW - I'll give it a go.

supakva

Thanks for the detailed reply P N. You are the compass man!!!

Cessna 210 Heavy

I thought '558 had been fitted with a GA type avionics fit? GNS530/430 for example,

Or is that total rubbish on my part?

BEagle

558 no longer uses the MFS. It has a 'General Aviation' level HSI system as that is all that's needed for VFR Permit-to-Fly operations.

foxtrot-oscar

Does anyone know if she will be at the Biggin Air Fair next month or not. The Biggin website is saying TBC.

Thanks

deltapapa

Just thought you would like too know due too a unsucessful compass swing today tomorrows planned local test flight (not display) wont go ahead you wiull have too wait till Friday. Hope it wasnt those magnetic rivets I used that are making both the nav and pilot compasses go wonky lol


the reason they are not flying 558 today is because they believe they can fit the remaining checks into the flight on Friday on her return to Bruntingthorpe & that decision was made before they did the compass swing yesterday.

XL391

I would imagine that when it is confirmed, they will remove TBC from the list.

Nobody knows just yet, not the pilots, Dr Robert, the engineers, it all depends on her final test flight and, if successful, how quickly her Permit-to-fly is issued and her display authorised by the CAA. Only once all that is done can they be certain of when they will be appearing where. There is also the not inconsiderate matter of money in the kitty...

Cessna 210 Heavy

How about the funding? Do they have all they need to fly it at BIG? I thought they only had funds to complete the test flying? I am sure they still have all the display authorisations to go through, for each crew member, which will be a big deal on a 4 engine bomber like vulcan 'tis!

Vox Populi

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That really is inexcusable.

forget

Don't worry yourself too much Vox. The BCC new wot I ment. It's been changed.

supakva

Anybody got a time of departure for tomorrows test flight??.

Thanks.

Pontius Navigator

I was trying to give a generic answer about compass swings. Whatever the system it is likely to use flux valves and these need to be aligned accurately on the aircraft effectively a coarse alignment, and then elecronically to give an accurate magnetic reading.

As for an aircraft acquiring a magnetic alignment this is true of any ship or aircraft on one heading for any length of time. Or indeed its components. In service an aircraft, even on a major repair programme, would not be on one heading for more than a year or so.

A compass swing was supposed to be given after a change of magnetic latitude or a major component change. The change of magnetic latitude is due to Dip where the magnetic field is horizontal near the equator and therefore stronger and near the vertical at the poles and therefore very weak in the horizontal plane. In the case of component change there were arguments that an engine change was 'major' but that was eventually ignored as TFD as indeed was the rule for magnetic latitude, same reason, TFD. It was argued successfully, and probably wrongly, that the trucks didn't do compass swings down the route so why should a bomber. This overlooked the need for greater accuracy in a bomber. I never did a compss swing on detachement.

Ballast

Doesn't seem unreasonable to describe it as the "British Royal Air Force" as, believe it or not, other countries have royal families and then have the audacity to called their forces "Royal".

Pontius Navigator

As the first Royal Air Force we had no need to stipulate which country it was from.

While the Dutch, French and Spanish had Royal House the case for our Navy to be only the RN is interesting.

Then again we were the first with postage stamps so no need to put a country name on them. Ditto the Royal Mail and the GPO.

Tim McLelland

I see from the press release that XH558 is due back at Bruntingthorpe at lunctime tomorrow and then the papers go to the CAA. So, no matter how you look at it, they did it, and despite all the sagas, the disappointments, shady activities, arguments, whining and bitching, the project has been completed and I have to say - hats off to 'em!

Of course, there's no certainty what will happen from this point onwards but I certainly wish the team the very best of luck. They've achieved what many believed to be impossible. Just hope it doesn't prove to have all been for nothing - you'd think a sponsor would have come forward by now, wouldn't you? Oh well, a classic tale of determination against typical British indifference I guess.

TEEEJ

The graceful lady as she basked in the sunset earlier this evening.



Cheers

TJ