Blenheim Aerials

[Walter Lindekens]

Hi all,

My first post here! Been visiting this forum for quite a while and noted there's a lot of British WWII aviation knowledge around. I have to admit I haven't built a model for ages (do want to take it up again some day though, when I find the time) but I owe messrs Airfix a life long passion for British WWII aircraft and so for many years now I've been happily collecting all sorts of reference material.

Being a big Blenheim fan I noted variances in aerial fit which none of the published side views or scale plans appear to portray correctly. Something else these side views and drawings tend to overlook is the presence of IFF aerials.

The problem with aerial wires is that being just a thin steel wire (anyone know what dia these actually were?) they hardly show up on photographs, the only give-aways that they are actually there being the aerial masts and the insulators.

Having studied dozens and dozens of photographs in various books I concluded there were two major variations which I have tried to represent graphically in the below drawings. Note I am focusing on the Mk IV.

The differences between A & B are the shape of the mast itself (straight broomstick type or tapered) and the presence of a fairing protecting the aerial lead-in point in the fuselage.

The second variation is where the tapered mast gets a bulge on top. From most photos it is impossible to make out what this bulge is but some time ago I was pointed to a website dedicated to 404 Sqdn (www.404squadron.com), the photo album on which contains several shots of Blenheim air- and groundcrew. Though intended as portraits some of these photos have been composed in such a way as to reveal a wealth of airframe details!

Photo PL07692 shows that the bulge on the mast is in fact a two part pressed alloy fairing but what is it for? It doesn’t seem to be there to cover the aerial attachment which is at the back of the mast, the fairing only covering the front.

PL07699 shows the “secondary aerial” that I depicted in red on the drawings, photo PL07716 then shows how this attached to the starboard tailplane. So far this is the only photo I found depicting such a long secondary aerial, all others seem to have the shorter version as in C. Of note is that this secondary aerial as I call it does not attach to the mast but actually crosses the main aerial, some photos show a slight kink in the main aerial at the crosspoint.

As for the IFF aerials, from various photos (mostly taken by airgunners from their turret hence rather unsharp) it was clear that these attached to the underside of the tailplane tips (unlike on the Spitfire which has an attachment on the tailplane leading edge) and then 404 Sqdn came to the rescue again with photo PL07705, on which one can see a wingnut below the tailplane tip!

Originally the Blenheim was fitted with the T1083/R1082 transmitter/receiver which by 1941 were replaced by the T1154/R1155 set. A TR9 radio set was then also fitted for use by the pilot and which permitted voice communication as opposed to morse.

What I now would like to know is if that secondary aerial would point to the aircraft being fitted with the TR9 set and what that bulge fairing on the aerial mast is for! The Air Publication Vol I that I have for the Mk IV does not give any info on radio installation, unlike the Vol I’s for other aircraft I have.

Answers or just ideas would be much appreciated!

Cheers,

Walter

[Edgar]

Sorry, talking twaddle.

Edited November 29, 2011 by Edgar

[Chuck1945]

First

Interesting info, thsnks for posting

[mhaselden]

Sorry, talking twaddle.

Edgar,

You're not allowed to talk twaddle. That's MY job! I'll 'ave the union on you!! DEMARKATION!!!

[Edgar]

Edgar,

You're not allowed to talk twaddle. That's MY job! I'll 'ave the union on you!! DEMARKATION!!!

You're on strike, tomorrow, so who cares.

[mhaselden]

Oh no I'm bluddy not! Never been on strike, never will go on strike. Then again, I count as "management" which obviously makes me the enemy of "the workers".

I think I'll leave it there in case this descends into politics, which would be a shame 'cos this has the makings of an interesting thread.

Cheers,

Twaddle-talking Mark

[brewerjerry]

Hi

.......Photo PL07692 shows that the bulge on the mast is in fact a two part pressed alloy fairing but what is it for? It doesn’t seem to be there to cover the aerial attachment which is at the back of the mast, the fairing only covering the front........

Now this is just a wild guess, but it might be a water spray deflector ( splash guard ) covering the termination of the aerial, to help stop corosion/seizing of the connection,( tensioner ?),and maybe stop water shorting out the connection.

Cheers

Jerry

Edited November 30, 2011 by brewerjerry

[Seahawk]

Edgar,

You're not allowed to talk twaddle. That's MY job! I'll 'ave the union on you!! DEMARKATION!!!

What's demarkation? The removals of Marks from forums?

[gingerbob]

I don't know, I never had a vacation in Denmark, though I intend to.

Walter, welcome to the nuthouse- I trust that after we've had our fun someone (besides Jerry) will come forth with some thought having been given to your questions...

bob

[mhaselden]

"Demarkation" was an oft-heard call from a worker to his/her union rep during the 1970s. It was issued when the worker perceived that management was trying to reduce costs by "multi-skilling" the workforce (ie getting people to do more than one thing). By defining the scope of each job, workers and unions hoped to preserve a larger workforce but it failed in the commercial sector as market economics drove efficiencies and the poor old "nut tighteners" had to accept that their job could be done equally as well by the "nut looseners" and vice-versa (the last part is made up but it illustrates the point).

The fact that there's a massive strike today in Blighty by government workers shows that unionism is still alive and well in the public sector workforce, as illustrated by Edgar's post.

Of course this has nothing to do with the far more interesting subject of differing radio aerial configurations on Blenheims...

We will now return to our normal programme.

[Nick Millman]

Those whom the gods wish to destroy they will first make mad by trying to work out all the permutations of aircraft aerial wires.

[GrzeM]

Do you know this photo?

...and more here:

404 squadrom album

[Prop Duster]

Walter first:

Second, your question does have merit-the various noted antenna configurations were the result of how and type of radio equipment was used. Morse code, vs voice- long distance etc.

Also indiviual flight commanders were given a special form to fill out to request how his aircraft antenna was to be strung as the crew would use it to hang out the washing on laundry day, so it would be ready for ironing at the end of the mission.

[Walter Lindekens]

Hi guys,

Thanks for the warm welcome and the twaddle (had to look that one up in my dictionary so thanks to Edgar I have increased my English vocabulary with yet another word!) !

Jerry,

Thanks for the water deflector suggestion. Why not but then why only on the Blenheim as I can't think of another type of the same era with a similar arrangement on the aerial mast.

GrzeM,

That is one of the photos I am actually referring to in my initial post. Lovely collection of photos on that 404 Sqdn website, isn't it?

Prop Duster,

Nice touch that, the longer secondary aerial on the 404 Sqdn aircraft might then point to a crew with more laundry than average! And we haven't even discussed the trailing aerial and its obvious use for fishing whilst crossing the Channel on the way to occupied Europe !

I just hope that some day some one might come up with the definite answer as I find this all very intrigueing!

Cheers from Belgium,

Walter

PS Already preparing another tricky Blenheim question!