R/T or W/T trivia question.

R/T stands for Radio Telephony (speech, using audio frequency modulation on the carrier wave). I agree that you can choose either speech or Morse (but my expertise is in radar!)

Hi James,

A little bit more on this topic. With Papa Lima’s information as well as some other info that I was reading today, I definitely believe that the I.C.W. switch controlled morse code transmission.

The switch on the Wirraway has two-positions: I.C.W./C.W. and R/T (Radio Transmission, I’m assuming). I’m assuming that normal aircraft operations would have the switch positioned to R/T, and in the event that any morse transmission was required, then it would be switched over to I.C.W/C.W. Based on this theory, it would mean that morse transmission would be impossible when the radio system was set for normal R/T ops. Would seem to make sense – well, in my mind at least! Always interested in hearing an expert opinion from someone though.

Cheers,
Matt

Continuous wave is transmission of a radio signal on a fixed frequency. This of course can be interrupted, for example into short (dots) and long (dashes) to send Morse code. There are other uses such as IFF (Identification Friend or Foe) which is a coded series of pulses.
When a radio wave is modulated, for example by an audio signal, it can be used for speech transmissions. Even Morse code can use a modulated signal, with long and short bursts of modulation at a fixed audio frequency.
This all takes me back to my days as an Aircraft Apprentice at RAF Locking 1959-1962 (93rd Entry).

Thanks Matt,
Most useful. All the Radio hams and nuts I know I’m not in touch with, at the moment, but I’ll have a further dig.

A clue is that both the Wirraway and the Lysander were expected to be able to undertake Army co-op work in the British Empire standard and late thirties design era…
Cheers
James

G’day James,

Interesting question mate, and as I knew the Wirraway also had an I.C.W. switch, I thought I’d try to find out exactly what it was as well. Pulled out some original manuals this afternoon, and eventually came across some sort of answer.

PaulR is correct that I.C.W. stands for Interrupted Continuous Wave. The definition I stumbled across describes it as “A radio frequency wave interrupted at regular intervals of an audio-frequency”. I’m far from a radio expert, so I’ll assume this is like sending morse code, as PaulR gave the example of.

There is also a Continuous Wave (C.W.), that is simply “a uniform radio-frequency wave”, as well as a Modulated Continuous Wave (M.C.W.). From the radio units described in the manuals I looked in, it seems like I.C.W. and M.C.W. aren’t possible on the same unit. I’m certainly not stating that definitively though.

Hope this is of some interest mate. If you ever feel the need to be completely confused by the topic, I can show you the relevant sections in the manuals. Thanks for raising this topic – made me learn something as well.

Cheers,
Matt

Just finished reading Hugh Verity’s “We Landed by Moonlight” – no references to those items I’m afraid.

Good, isn’t it?

I suspect that this item is an army co-op requirement, and would have been long gone when the Spwecial Duties (SD) Lysanders were in service. It’s often not realised that the SD aircraft were a rebuild / major refurbishment, mostly of TT airframes, which themselves were mostly mods from the original version.

Having been doing a lot of fact cross checking, I can also say that the Verity book is an excellent volume of good data – even the bits he’s not sure about he presents well, and honestly.

If you’ve enjoyed the book, it’s worth seeking the SOE film out ‘Now it Can Be Told’ from DD and the IWM; not a great film in terms of thrills, but a remarkably accurate film story of the work of the SOE. The RAF Museum’s Lysander, as JR-M features, as well as brief shots of Halifaxes, Sterlings and a major bit by Hudson.

The RAF Museum’s Lizzie is today the only genuine SD survivor. Of course, the RAF Museum have it presented in it’s earlier colours as an army co-op aircraft, but with the internal long-range oil tank visible and the rear cockpit still configured as (SD) aircraft were set up.

Just finished reading Hugh Verity’s “We Landed by Moonlight” – no references to those items I’m afraid.

Thanks for the suggestions, various, chaps!

Glad to see I’m not the only one who doesn’t know…

Any other offers?

Hi folks,
Just looking at a set of pilot’s notes for the Lysander, and there’s a reference to an “I.C.W. Switch”, which I think is something to do with the wireless, but as I haven’t the faintest what it is, I don’t know. Anyone know?

Incidentally, Item 70 is an “elastic band” – not part of the engine, but perhaps for flicking at annoying 109s?
TIA

Item 70 – in lieu of bicycle clips for short field landings at night perhaps 😀

I personally think it stands for Interrupted Continuous Wave, where a continuous tone is created by switching a transmitter on and stopped by switching it off – for example, sending morse.

Could it be “Identification Carrier Wave” for continuous transmission to be used by HF/DF to identify the bearing of the aircraft?
A pure guess!