Author Topic: Junkers J1 / J4 technical stuff...  (Read 271 times)

Offline Matt

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Junkers J1 / J4 technical stuff...
« on: December 11, 2018, 07:43:46 AM »
Hi all

As well as my WNW Camel Comic, I have been working on and off on the WNW Junkers J1. I have discovered a lot of stuff so far (things that need to be added to the kit as presented) by looking at as many photographs and drawings as I can find.

I'm happy to share that as I progress the model (I should start a thread). One thing I cannot understand (and I suppose some of this is a need to understand and not necessarily something that'll make a visual difference to the model) is the cooling water system. I know where everything is, except that the translated German instructions that appeared in a 1920(?) issue of Flight mentions being careful to top up the water tank before flight.

My knowledge would say that the tank has to be higher than any other part of the water cooling system. So, as the radiator is slung beneath the top wing, the coolant water 'header tank' would have to be inside the wing. That isn't an issue as the gravity tank for the fuel is in the top wing and visible in views of top wing with outer panels removed (it is on the stbd side).

What I can't figure is how it would be filled? There's no sign of a filler on the top of the wing (and it'd be a right faff getting up there to top up every time).  It's a long shot, but I wonder if anyone has any knowledge or idea of how this system would have worked. I suppose my main initial question would be does the header have to be higher than the rest of the cooling system?

TIA

Matt

Offline krow113

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Re: Junkers J1 / J4 technical stuff...
« Reply #1 on: December 11, 2018, 10:45:48 AM »
 In a water cooled system there usually is no 'tank' as we know it. It has to be factored in that these were burgeoning systems ,perhaps no-one knew that water boils 3 x faster and 3 x hotter under pressure when these cooling systems were first designed. You can see some weird stuff on WW1 aircraft.
Tank may have been a suitable word in that time period to describe the radiator(regarding the manual you quoted ) . You are right in the assumption that the filler cap would be the highest point , factoring in the properties of water. Start there and figure the system out , there aren't a lot of components. Rad/tank , lines/hose' , water pump , cylinder jackets , temp guage and that's about it.

Offline Matt

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Re: Junkers J1 / J4 technical stuff...
« Reply #2 on: December 12, 2018, 07:07:35 AM »
Thanks

Yes, that's what I'm trying to ascertain...

Well, I think I've found it.

Photo 1. Excellent topside of upper wing view. Look, there's a little round shadow dead centre. I've (badly) circled it.



Close up. Circular hole with hint of a cap...



Taking what you said about not taking 'tank' too literally, I looked underneath and behold a pipe goes up into the wing at about the same point as the filler we see on the top wing. So probably no tank in the wing, merely a filler leading via this pipe into the radiator.. another mystery solved..



Thanks for the inspiration Krow113

Matt

Offline krow113

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Re: Junkers J1 / J4 technical stuff...
« Reply #3 on: December 12, 2018, 09:06:06 AM »
Good work!

Offline lcarroll

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Re: Junkers J1 / J4 technical stuff...
« Reply #4 on: December 12, 2018, 09:53:37 AM »
Matt,
    A good friend of mine and fellow Forum Member Gary Barling did this Kit several years ago and a great part of his research was done on the re-built example (and I believe only surviving example) in the Canadian Aviation and Space Museum in our capital, Ottawa. Gary examined the top surface of the upper wing to document the camouflage pattern and might be able to supply you with more info. The aircraft is on display now at the Museum but I've never seen the upper wing surface. Gary's moniker here is "Trackpad" if you want to pursue this.
Cheers,
Lance

Offline Matt

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Re: Junkers J1 / J4 technical stuff...
« Reply #5 on: December 12, 2018, 10:50:34 AM »
Thanks Lance

I shall ask Gary. He provided me with a series of photos of the Canadian machine (some very useful and excellent details revealed). I shall seek him out as I'd like to ask if he minds me using a couple of his photos to illustrate my build.

His photos secured the evidence I needed to confirm my hunch that the J 1 had variable intake and outlet flaps on the radiator... The more you look at it, the more fascinating the aircraft is...

I'm still trying to work out where the electrical cable is going to/coming from on the side of the fuselage. I can see the engine has the 'gubbins' to fit a generator - needed for the radio equipment in the observer's station... But I have heard that this machine was also being used to take cine film using an electrically driven camera. Now, did the aircraft need a second generator to supply that power? Did it have a wind driven generator attached to the u/c to supplement the engine driven one? No idea at the moment..

Matt

Offline mike in calif

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Re: Junkers J1 / J4 technical stuff...
« Reply #6 on: December 13, 2018, 09:09:07 AM »
Nice catch on the filler cap location. I also see that the colors are at about 60/40 green to purple(mauve) slightly more green. Possibly they used a generator big enough to power both units, fed from a common j-box?