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PostPosted: Fri May 29, 2009 8:23 pm 
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:D, Hello all,
I've also post this question inthe modelling section of the forum. I read somewhere on the web or in a book that the Woomera used Wirraway outer wing panels. Can anyone confirm or deny this? JDK?

Cheers,
Ross.


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PostPosted: Sat May 30, 2009 4:01 am 
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No. I'm no expert, but I've just had a quick look in From Wirraway to Hornet the history of CAC, and it doesn't mention that idea. It also talks about the structure of the Woomera's wing, and the integral tanks in the wing centre section - I'd be surprised if the Wirraway / NA-16 wing design would be tough enough for a twin engine dedicated dive and torpedo bomber. Yes, the Wirraway was adapted as a dive bomber, but the size/engineering difference, even in the same role would be significant IMHO.

Related facts - the Boomerang's centre section was originally built in a Wirraway type jig, but was heavier construction. The Wirraway / NA-16 outer wing panels were adapted with dive brakes by CAC, which worked, but were later wired shut in service due to landing issues.

HTH, better input from others welcome!

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PostPosted: Sat May 30, 2009 4:08 am 
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There has always been a legend that the Woomera used Wirraway wing outer panels but there is little to confirm that situation.

Unfortunately Wackett's own autobiography spends no time describing the Woomera other than a solitary photo.

Photo's show the wing outer panels have significant differences to standard Wirraway outer panels in the areas of wing tip and aileron, the Woomera has a much wider and longer aileron than extends along the trailing edge to the tip of the wing.

The plan drawings available of the Woomera that I have access to are not scaled, and compared to photos in fact seem to have errors in the wing proportions in any case showing the wing more to be stubby like a Boomerang (strange given the drawing is in the official CAC history book "Wirraway to Hornet")?

That same book makes no mention of the use of major Wirraway components and in fact refers to 7 seperate bomb stations across each outer wing, (which I think may not be standard on the wirraway wing outer and suggest significant beefing up internally) and photos show a complex dive bomber flap design on the inboard section of the outer wing panel similar to but larger than the Wirraway dive-bomber wings, which it pre-dated. (The Woomera was designed to be capable of dive bombing and torpedo bombing, and in many ways was superior to the Beaufort on paper.)

The book describes the wing as a single spar, which is the same as the Wirraway, and the Woomera shares the same straight trailing edge wing plan as the Wirraway and Boomerang, as inhereted from the NA-16 and acquired by North American from the Douglas DC-2.

In photos the Woomera wing outer panel bears great resemblence to the cord and sweep back of the Wirraway and I suspect the design is based on the Wirraway component, perhaps to speed up production?, although the design originated in 1940 and pre-dates the "urgency" of Pearl Harbour that caused the Boomerang to be created from Wirraway components.

I think if you are modelling the Woomera, a Wirraway wing plan would be fine, other than incorporating the obvious changes to the flap ,and the aileron and wing tip.

regards

Mark Pilkington

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PostPosted: Sat May 30, 2009 4:11 am 
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:D,Thank you James,
Probably I just imagined I'd read that somewhere, but I was pretty positive I had. What you've said makes a lot of sense to me now but there is a pic on the web (I saw it last night) of a Woomera with the sun almost overhead and the outer panels look very Wiarraway-ish to me but appear to have some sweep back on them. Is this correct or just a trick of the light?

:roo:
Cheers,
Ross.


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PostPosted: Sat May 30, 2009 4:26 am 
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Ross,

One of the photos I preused before replying to you shows the later CA-11 A23-1 side on and close up and I believe there is no sweep back in the trailing edge.

A similar (or same) photo to that you describe is shown on page 54 of the Wirraway to Hornet book, of the earlier CA-4 Woomera banking away from the camera, and I believe the wing is a straight trailing edge but showing you an apparant sweep back due to the diheidral of the two wing outer panels relative to each other, if you focus on the RH wing outer to its adjoining inboard centre-section trailing edge, rather than from wing tip to wing tip the trailing edge appears very staight.

On the same page a side on shot of the CA-11 suggests a swept back trialing edge, but this is due to the photo being taken in line with the leading edge.

Despite my earlier concerns of its accuracy over its stubby proportions, the 3-D drawing on page 269 of the same book clearly shows a straight trailing edge tip to tip.

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Mark Pilkington

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PostPosted: Sat May 30, 2009 4:55 am 
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:D, Thank you Mark,
I've been perusing a pic of the Ca-4 on the ground and the shadow of the wings looks like a boomerang I now believe because of the light. There is a pic of the Ca-11 below that one on the website I was looking at and I have to agree, the trailing edge is quite straight with no sweep bck at all. I'm trying to do some research for a possible future model, a long time into the future I might add as I have so many other projects on the boil or off the boil at the moment.

:roo:
Cheers,
Ross.


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PostPosted: Sat May 30, 2009 1:41 pm 
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Look on the bright site.
They made a good crop duster out of them :idea:

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PostPosted: Sun May 31, 2009 8:15 am 
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Hi Jack. I hope your implying that part about the cropduster being about the Wirraway :P Its a pity the woomera never made it to full production...it would have been interesting to see how they fared in combat.

Chris


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PostPosted: Sun May 31, 2009 10:19 am 
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When this thread started off and said it used Wirraway outerwing panels.
That threw me off a bit and I though it was a reference to the Ceres. But the name used didn't jive.

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PostPosted: Sun May 31, 2009 4:23 pm 
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Hello Jack,

The Woomera was an in-house Bomber design at CAC that pre-dated the Boomerang, two prototypes were built, the CA-4 and the later CA-11.

Below info and photo from wiki http://en.wikipedia.org/wiki/CAC_Woomera

Image



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In 1941, because of a need to replace the Bristol Beaufort and Lockheed Hudson, the RAAF issued Development Specification No. 241. This stipulated an aircraft suitable for: reconnaissance, general bombing, torpedo delivery and dive bombing.

CAC, under Sir Lawrence Wackett, began to re-work an existing, unbuilt design, the CAC CA-4 (sometimes known as the Wackett, and not to be confused with the unrelated CA-6 Wackett single-engine trainer). A prototype CA-4 took to the air on September 19, 1941. The CA-4 was a low wing, twin-engined, dive bomber with a crew of three. It was armed with four nose-mounted .303 calibre machine guns and two remote-controlled twin machine-gun barbettes mounted at the rear of the engine nacelles. It could carry either 500 lb (230 kg) bombs, 250 lb (110 kg) bombs or two torpedoes. It was originally powered by two Pratt & Whitney Twin Wasp R-1830-S3C3-G radials. (The CA-4 prototype was scrapped in 1943 after it suffered major damage, from a mid-air explosion due to a fuel tank leak and a consequent fire.)

With a re-designed tail and rudder, and an improved nose armament of two 20 mm cannon and two .303 calibre machine guns, the CA-4 became the CA-11


Wiki is in-correct in regards to the date of the development order for the Woomera, it was not issued in 1941, but actually issued in April 1940, and was primarily due to concerns over the progress of the Australian Beaufort construction project which was suffering major technical and management problems at the time, (the first Australian Beaufort didnt fly until August 1941) and the Beaufort itself was intended to replace the Hudson.

It would have been interesting to see how the Woomera would have performed in both the Beaufort and Beaufighter roles, for which it was effectively competing with for production orders.

Had the Beaufort project not been rescued by Essington Lewis and a replacement management team from GMH, the Woomera may well have been rushed into production in response to Pearl Harbour despite the problems with the CA-4, and the improved CA-11 version later developed and used to fill the role of the DAP Beaufighter.

Had the DAP Beaufort project failed, the follow on production of Australian Beaufighters probably would not have occurred, and CAC would have remained the dominant aircraft manufacturer post war.

The Woomera had a steel tube fuselage, and wing/centre-section all based on the Wirraway design and construction methods, so in a similar way to the Boomerang and Ceres, can in someways be considered to be the only twin engined decendent of the NA-16 and cousin in the T6/SNJ/Harvard family.

regards

Mark Pilkington

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PostPosted: Tue Jul 07, 2009 9:42 am 
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105 production CA-11 Woomera's had been ordered by the RAAF with one prototype built and 20 on the production line when the order was cancelled.

The 105 aircraft order had resulted in sub-contractors undertaking production of sub-assemblies with many of these still occasionally popping up.

Some years ago I was given a box of cad plated 04- fittings which were the blind flying hood mounting brackets, and previously I had purchased a Woomera Trim wheel found in an antique shop in Tassie.

More recently I found this twin oil cooler shutter control on ebay.

part number 11-43029

http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=120439959087&ru=http%3A%2F%2Fsearch.ebay.com.au%3A80%2Fsearch%2Fsearch.dll%3Ffrom%3DR40%26_trksid%3Dp2773.m37.l1313%26satitle%3D120439959087%26category0%3D%26fvi%3D1

Image

Image


regards

Mark Pilkington

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PostPosted: Sun Feb 21, 2010 9:44 am 
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Hi there Ross, et al.

I'm late to this thread, but here is some data to show clearly that the Woomera did not use Wirraway outer wing panels. Below is a scan of a Woomera drawing (an old CAC drawing held at Moorabbin air museum) with the outer panel structure of a Wirraway wing overlaid at the same scale. They both have the same leading edge sweep and single-spar construction, but that's where the similarities end. The Woomera has a forward-swept trailing edge, and closer spaced ribs (hence stronger construction).

Cheers,
Derek

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PostPosted: Mon Feb 22, 2010 5:59 am 
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Hi Derek

can you do the same with the Boomerang wings?
I was of the opinion that the outer wings for the Woomera were the same as Boomerang.
Great thread this and would be very keen to have this clarified.


SD


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PostPosted: Mon Feb 22, 2010 6:20 am 
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SD,

The Boomerang conceptually is a clipped Wirraway wing then beefed up and fitted with a Cannon and magazine, with the Wirraway with a span of 43' and the Boomerang of 36' each wing outer panel is effectively 3.5' shorter than the Wirraway panel superimposed over the Woomera outer panel by Derek in the post above.

The Boomerang and Woomera share aileron and wing tip design, but the Woomera has the "dive bomber" split flaps of the Wirraway CA-10 design.

I am not sure the General Layout drawing Derek utilises can really be relied upon as proof of the trailing edge sweep forward, I have other CAC GA drawings and they are not intended to be accurate for construction or dimension, simply to show plan and elevation views.

regards

Mark Pilkington

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PostPosted: Tue Feb 23, 2010 7:59 am 
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SD,
as requested here is the sketch again with the Boomerang wing plan added. As Mark mentioned, in plan view, the Boomerang wing is a shortened version of the Wirraway wing, with different ailerons. But structurally and aerodynamically they are actually quite different.

I've relocated the overlays to match the leading edge of the outer panel, so you can see the leading edge sweep basically matches for all 3 aircraft. The Woomera spar also appears to be in the same location as the Wirraway spar. But the chord is longer, so its clear these weren't just Wirraway outer panels bolted onto the Woomera centre section.

I agree with Mark's comment regarding the accuracy of some CAC general arrangement drawings... they should always be checked against other documentary evidence for dimensions. However this particular Woomera drawing shows top and underside views of both models (CA-4 and CA-11) and on all 4 views the trailing edges have slight forward sweep (so the draftsman would have had to get it consistently wrong). But I'll leave that discussion open, I agree these drawings are still suspect until they can be checked against other evidence.

Regards,
Derek

Image

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