Televel Guauges – Stirling Bomber – Why so complex?

James,
You have to look at the function of the Televel to work through the logic. See post #4. Tail up or tail down doesn’t alter the fact that you have to wind the float to get a reading. You would get a different reading with the aircraft in a different aspect but you would still have to wind the float. In your photo, in the windows that can be seen by my failing eyes, there are some windows at zero and some at 120 gallons, too discrepant for your tail down theory. It really looks like a panel after a long flight, engine oil temp coming down. The later Smiths electric gauge was linked to a cork float on an arm that would rise and float independently, linked to a ‘variac’ that would send a different electric signal, with an old school painted adjustment on the dial if the petrol sloshed to the back of an inclined tank.

Two windows on a Televel wound by one fingergrabbenscheisserschtik implies two tanks serviced by two cables coming out of a twin window, stacked dial display. This is just a guess, because your twin window Televel is a fascinating variant. We need to find one and see if two cables came out the back, or buy one on ebay and smash it open with a hammer to see if there are two stacked dials.:)

Hi powerandpassion

Yes I agree with all that you say, you point out the only bugbear in my applied logic!

If you look at the photo of the engineers panel you can clearly see 14 thin black cables coming down from above, which I assume are the Bowden cables driving the 14 gauges, all the other wires leaving the panel are thick electrical cables.

I conclude that there is only one Bowden drive per dial and so the second display can only be a direct one-to-one scaling (as it is on the later meters) or some sort of gearing has been applied internally.

But as you point out the numerical indications – or lack of – are quite mad! Indeed it was the oddity of these numberings that drove me to set the question to the forum. The only possible explanation I have on reflection is:

1. This is a production photograph and so the dials are not yet calibrated AND
2. The two dial read outs are on two separate discs that are clamped together by a single bolt internally and calibration is done by filling the tank to a known amount then dragging the two discs around so that they are both indicating the right level – then the bolt is tightened.

If that theory is correct then the uncalibrated discs could be at any relative position in the photo – or even the wrong discs – or even no disc(s)!, they are just waiting for the instrument engineer to turn up!! This two disc theory also means that the bulk of the device can be the same for all the meters and only the discs need to be ‘specials’.

I suspect that these are just for the Stirling and as such there are no left anywhere, but I’ll put a search on ebay to monitor if anyone tries to sell one on.

Cheers
James

Tall tail but true

Hi All

I guess many of you have been worrying about the second readout on the Televel gauge, :eagerness: so here is a pointer to the answer.

This is a picture of the gauge that replaced the Televel gauge on a later Mark of the Stirling, it has two readouts – On Ground and Cruising! Should have looked at this earlier I suppose…..

Since the Stirling had many fuel tanks of widely differing capacity each of the gauges are different and must have been made specifically for the Stirling.

James

James,
You have to look at the function of the Televel to work through the logic. See post #4. Tail up or tail down doesn’t alter the fact that you have to wind the float to get a reading. You would get a different reading with the aircraft in a different aspect but you would still have to wind the float. In your photo, in the windows that can be seen by my failing eyes, there are some windows at zero and some at 120 gallons, too discrepant for your tail down theory. It really looks like a panel after a long flight, engine oil temp coming down. The later Smiths electric gauge was linked to a cork float on an arm that would rise and float independently, linked to a ‘variac’ that would send a different electric signal, with an old school painted adjustment on the dial if the petrol sloshed to the back of an inclined tank.

Two windows on a Televel wound by one fingergrabbenscheisserschtik implies two tanks serviced by two cables coming out of a twin window, stacked dial display. This is just a guess, because your twin window Televel is a fascinating variant. We need to find one and see if two cables came out the back, or buy one on ebay and smash it open with a hammer to see if there are two stacked dials.:)

The ground angle of the Stirling under static load was nine degrees, twenty-six minutes and the spar incidence was one degree, fifty-two minutes making eleven degrees and eighteen minutes for the fuel tanks.

Peter.

True – Goodness knows where I got 22 degrees from – possibly from the cockpits height above ground!?

James

The ground angle of the Stirling under static load was nine degrees, twenty-six minutes and the spar incidence was one degree, fifty-two minutes making eleven degrees and eighteen minutes for the fuel tanks.

Peter.

Hi All

I guess many of you have been worrying about the second readout on the Televel gauge, :eagerness: so here is a pointer to the answer.

This is a picture of the gauge that replaced the Televel gauge on a later Mark of the Stirling, it has two readouts – On Ground and Cruising! Should have looked at this earlier I suppose…..

Since the Stirling had many fuel tanks of widely differing capacity each of the gauges are different and must have been made specifically for the Stirling.

James

[ATTACH=CONFIG]236131[/ATTACH] my Sunderland one…looks like the tank number was stamped on the wing nut .

These gauges were also fitted to Sunderlands James….

Hi Hindenburg

Just looked up the AP for the Sunderland I – it mentions the Televel gauges and how to use them but add that there is a (paper) conversion chart supplied to convert the reading to ‘on water’ and with wingtip up and wingtip down. So it does look like the angle of the tanks was an issue but still no clear evidence yet what the lower window displayed on the MKI Stirling version.

James

Hi Hindenberg

Hmmm, yes of course I should have remembered the Sunderland connection. Had a quick Google but no immediate hits on any pics of the engineers panel, but I think RAFM have a Sunderland and I am going there soon so I guess I can take a look, though knowing my luck this will be a late version Sunderland with more modern dials!

Hi bazy

I had wondered about other aircraft using this equipment, even small fighters tended to sit nose high. Then again I wondered how you could fill the tanks fully when on the ground if they were tilted, even the dipsticks would need some design considerations with regard to calibration and the ability to determine the in-flight fuel level.

Generally I’m still not convinced of any theory, but possibly the Sunderland route or the research people at RAFM will clear the mystery up!

James

James

Even on smaller tailwheel aircraft it was quite normal to have ‘level’ and ‘tail down’ (eg ‘ground’ and ‘flight’) calibration on fuel gauges !
Both sets of readings are very important although it would be fair to say that some aircraft gauging is ‘approx’ : )

Just had a thought…..

On the ground the Stirling sat at about 22 degrees to the horizontal, possibly the second read out was for ‘ground’ level adjusted to compensate for the different level taken up in the tank by the fuel? So ‘upper’ for flat level flight and ‘lower’ for ground. This thought was triggered by the word ‘CRUISING’ on all the pics of the Televel that I have.

On the blank dials it may be that the tank was too small to make any difference in terms of the petrol level?

Possibly then this was a ‘special’ gauge for the Stirling?

James

These gauges were also fitted to Sunderlands James….

German Silver = Nickel Silver
http://en.wikipedia.org/wiki/Nickel_silver

I’m surprised to see that the float was made from ‘german silver’. I’ve never heard of this material before but I suppose it to be an alloy of Tin which is unlikely to contain any Silver.
I could just imagine some poor FE tapping the gauge and muttering “Damn these blasted Jerry floats.”

Hi PowerandPassion

Looks like we cross posted! Here’s the Engineers panel (different on later marks). The gauges are also in different colours. I think that the ‘wires’ entering the panel from above would be the Bowden cables.

The readings on the ground would be different if the tank was tipped appreciably.

James

Just been drawing some lines on the dials and the second readout isn’t clearly related to the first – for example the numbers are both at a 30 degree pitch but they don’t both reach zero together so one isn’t a multiple of the other.

If you consider the ground/flight theory then work out what the effect would be in tipping the tank by say 22 degrees the read out might be distorted like this:

Tank Content Gallons 0 10 20 30 40 50 60 70 80 90 100
Reading in level flight 0 10 20 30 40 50 60 70 80 90 100
Reading if tipped……. 0 0 0 16 32 47 53 72 100 100 100

The float gets left high and dry too soon with low fuel content and reads 100% well before the tank is actually full. So to make this sensible you might imagine that Televel calibrated the dial correctly as follows but left the extreme ends of the gauge blank to mean ‘don’t know’

Tank Content Gallons 0 10 20 30 40 50 60 70 80 90 100
Reading upper window 0 10 20 30 40 50 60 70 80 90 100
Reading lower window ……….. 30 40 50 60 70 …………

Possibly not a lot of use on the ground but may have stopped people using the gauge instead of a dip stick!

James

Just had a thought…..

On the ground the Stirling sat at about 22 degrees to the horizontal, possibly the second read out was for ‘ground’ level adjusted to compensate for the different level taken up in the tank by the fuel? So ‘upper’ for flat level flight and ‘lower’ for ground. This thought was triggered by the word ‘CRUISING’ on all the pics of the Televel that I have.

On the blank dials it may be that the tank was too small to make any difference in terms of the petrol level?

Possibly then this was a ‘special’ gauge for the Stirling?

James

An interesting thought but a single window would allow you to just wind it up on the ground and get a ground reading, same in the air for an air reading.
With 14 cables are there 14 televels in the Stirling?
Or 7 tanks with 4 dual Televels allowing 8 readings, one reading window being unused.
If tanks are linked by plumbing, maybe more than one reading is unused, but you still need to run bowdens to distant tanks, so 4 Televels are required.

It seems straightforward to have two internal bowden reels and two readout dials of different circumferences in one gauge, which they appear to be.

Just had a thought…..

On the ground the Stirling sat at about 22 degrees to the horizontal, possibly the second read out was for ‘ground’ level adjusted to compensate for the different level taken up in the tank by the fuel? So ‘upper’ for flat level flight and ‘lower’ for ground. This thought was triggered by the word ‘CRUISING’ on all the pics of the Televel that I have.

On the blank dials it may be that the tank was too small to make any difference in terms of the petrol level?

Possibly then this was a ‘special’ gauge for the Stirling?

James

Hi PowerandPassion

Thanks for the attachments – clearly no amber light! In fact no electrics at all….

I’ve been studying all the pics I have of the Stirling Engineers panel and have only come up with the following:

1. The second window is radially smaller than the ‘normal’ window which can mean that the graduations are either painted on the same internal disc or that they are on different discs, on the figures that I can see they both increase clockwise tending to suggest they are on the same disc as gearing could imply that they rotated in different directions – sadly nothing conclusive there I just felt a little more detective than confounded…

2. I wondered if the second dial simply showed the weight of the fuel as opposed to the number of gallons, so it would simply be another set of numbers, but I can make out the word ‘level on that window, but even then ‘level’ makes no sense if the readout is gallons or weight….. However one of the gauges that does have numbers in does seem to support this idea, others however have a clear zero on one dial and nothing at all on the other!

3. Many of the dials are completely blank – that seems a bit mad too. However many of the internal pics of the Stirling are taken during production and so these dials may not be calibrated or set up.

4. There are 14 Bowden cables going into the panel and so there is only one source of movement for each of the 14 gauges ruling out each gauge going to two tank floats and meaning that the two readouts are either a) painted on the same disc or b) geared in some manner. One read-out cannot be simply a magnification of the other (as in a vernier drive) since that would require numbers all around the circumference of the dial and that is clearly not true. In any event only one winding handle must mean only one float.

So, I’m still stumped! The Stirlings tanks were between 63 and 254 gallons so each gauge would also have had to have different pitch to the numbering just to make things more complex. I can’t imagine anything else useful that the engineer might need.

Cheers
James

Instructions

How it worked :

[ATTACH=CONFIG]236039[/ATTACH]

Televel Tales

James,
Below are extracts from AP 1275 Instrument Manual 1937 which I trust explains how it all works. There is also a picture of a gauge which hitherto I understood only had one window. I can only assume the Televel concern piggy backed two reels within the gauge to allow two windows for simplicity and economy of panel space in the Stirling. I can’t understand how you see an orange light in a B&W photo but an excess of Drambuie has also resulted in me seeing such things in other circumstances. I assume a late 30’s Stirling feature would be a lighting globe within the gauge, if two windows/readouts are possible, per your example. I love the Televel, it’s the Betamax camera/Cyndi Lauper/Presidential Candidate Spiro Agnew of its age, everywhere then nowhere.

[ATTACH=CONFIG]236033[/ATTACH]

[ATTACH=CONFIG]236034[/ATTACH]

[ATTACH=CONFIG]236035[/ATTACH]

[ATTACH=CONFIG]236036[/ATTACH]

[ATTACH=CONFIG]236037[/ATTACH]

[ATTACH=CONFIG]236038[/ATTACH]

Durrrr

Ignore the two gauges question – there are 7 fuel tanks in each wing of course :apologetic:

The other questions are hopefully still valid though!

James