Antiques Roadshow/Cockpit Discussion

[quicksilver-wsr]

Ah, but if you only have two, how do you know which one is telling porkies? You need three so voting logic gets rid of the duffer. Even that doesn't work every time.

Yes, this was the dilemma facing Amy Johnson/Jim Mollison, et al, with their compasses on the early trans-Atlantic flights. How many do you fit? So they fitted three, yet they were still paranoid things would go wrong and got spooked several times on the way! (By the way, I can't say I blame them!).

Our two systems operate by totally different methods, so the chances of them both being wrong simultaneously are millions to one against. The other thing in a WWSR scenario, of course, is that the driver will tend to have a pretty good idea of the speed he is going, just judging by the amount of throttle used over a particular timeframe of progressive acceleration and the distance travelled, so if a speedo suddenly shows 300 mph when a moment ago he knows he was doing 200 mph, he can be fairly confident it's the gauge that's wrong!

[kneeslider]

I wonder if K7's Pitot head suffered any issues with water ingress leading to instrument error on the ASI?

Come to think of it, as a Pitot head measures the stagnation pressure, and would need to have the static pressure subtracted from it to give the dynamic pressure (the actual air speed). So, does K7 have a static source somewhere on the outer skin?

As a Heli jock, Bill should know about all this!

[Renegadenemo]

As a Heli jock, Bill should know about all this!

The static side is plumbed to the base of the leading edge of the fin inside the tail fairing. If you study the pics carefully you can see an opening at the base of the fin to vent the interior. How well it worked is anyone's guess though I reckon we're going to find out.

[kneeslider]

If you study the pics carefully you can see an opening at the base of the fin to vent the interior. How well it worked is anyone's guess though I reckon we're going to find out.

Ta for that Bill, curious! The positioning of both the pitot head and the static vent would have had do be done with some thought in a marine environment because of all the water sloshing around. I'll have to have a good look at some pictures of the static vent on the base of the fin. Normally on an aircraft, it would just be on the side of the fuselage, but that would probably be too ready to be filled up with water. I wonder why it couldn't be put on the side of the fin?

[Renegadenemo]

The fin is straight off the Gnat and is stuffed full of structure and was never designed to have a static head in it. They took two lengths of aluminium pipe down the right-hand side then plugged them into a pair of yellow, plastic lines at the aft end of the engine cover for the final run to the fin. The static side was fitted with an air bleed, presumably to give some fine-tuning for the ASI, and they cut a slot at the base of the fin and pried it open. Typical K7 - a lash-up from one end to the other.

[malcolm uk]

Thats a great closing statement Bill ..................... just a pity that none of the true Anoraks has lept back on the attack and quoted DMC on the engineering involved in the endeavour.

Malcolm

[sheppane]

Thats a great closing statement Bill ..................... just a pity that none of the true Anoraks has lept back on the attack and quoted DMC on the engineering involved in the endeavour.

Malcolm

'' How are you going to improvise?''....

''That's just it... It's probably where the British are still the worlds masters.... the Right way to go about it would be to...''

There you go... A relevant DMC quote...

The truth is there was not to much money around... and therefore some of the solutions might not have been as elegant as those, on say CN7...

[Renegadenemo]

The truth is there was not to much money around... and therefore some of the solutions might not have been as elegant as those, on say CN7...

I'd wager that had CN7 had an as long, illustrious and successful career as K7 she'd have been a lash-up too by the end just as if the 1954 K7 had gone out and got a single record before being retired she'd likely be stuck in a museum nowadays slowly decaying but relatively true to her original design. I may describe K7 as a 'lash-up' and there's no doubt that that's the case... but what a glorious machine she is.

[lsrdatabase]

Thats a great closing statement Bill ..................... just a pity that none of the true Anoraks has lept back on the attack and quoted DMC on the engineering involved in the endeavour.

Malcolm

Thanks for that Malcolm, but I've given-up trying to correct such statements on this Forum, most members have closed ears to my comments!

But thanks anyway, Fred


'I'm just that bloke, who won't go away!'

[ace_chris]

Thats a great closing statement Bill ..................... just a pity that none of the true Anoraks has lept back on the attack and quoted DMC on the engineering involved in the endeavour.

Malcolm

By the very nature of being on this board and others, by defualt it makes each and every one of us an anorak!!! - I love the fact that K7 is a lash up from nose to tail, gives the old girl a personality. I bet gaffer tape and wd40 has been involved in practically every speed record attempt at some point Chris