Avro Anson Wingspan? XIX T.20/21/22/C.21

[wellsprop]

Hi,

 

I'm getting a bit confused about the Avro Anson wings, I'm currently CAD modelling an Anson XIX T.20/21/22/C.21.

 

As I understand these have the later, tapered, metal wing, which should measure 57'6" (as I understand) - whilst the original wooden wing measures 56'6" (according to the Aeroplane Database) - is this correct?

 

Secondly, I have been using the Aeroplane Database drawings, scaling them by the fuselage length, 268.2875mm (42'3" scale size)

 

I believe the below plan shows the later, series 2, metal wings (is this correct?). The half-span measures 179.388mm (56'6" full span scale size). I've put another line in a a half-span of 182.563mm (57'6" full span scale size). Am I too assume that the plan has drawn the later series 2 metal wings, but to the wingspan of the earlier wooden wing?

 

Where this gets VERY confusing is how I fix it... I could scale plan in span only, just to get the wing correct, but this would move the engines - are the engines in the correct place here?

 

Cheers,

Ben

[wellsprop]

Additional questions....

 

I have the dihedral as 4 degrees and the root incidence as 4.5 degrees with a NACA 2218 aerofoil at the root.

 

Does anyone know the incidence at the tip/washout and the tip aerofoil?

[rossm]

@John Aero May well know, Aeroclub released a XIX back in the day and he was always hot on accuracy.

[Ossington 2]

I've just checked my best Anson reference, NACA 201, dated Mar 1936.

Span: 56ft 6ins

Wheel Track: 13ft 8ins

Engine Centres: 13ft 8ins 

Might be of help.

[BS_w]

[wellsprop]

22 hours ago, Ossington said:

I've just checked my best Anson reference, NACA 201, dated Mar 1936.

Span: 56ft 6ins

Wheel Track: 13ft 8ins

Engine Centres: 13ft 8ins 

Might be of help.

 

11 hours ago, BS_w said:

Thanks for these, although I don't think either are applicable to the later, postwar, Anson XIX 19, 20, 21, 22.

 

These were manufactured from 1945, with the later metal wing.

[Graham Boak]

I'd expect the wing centre-section to remain unchanged and any difference in span to appear in the outer panels.  In which case things like wheel track will remain as before.  One way of checking whether the engines are in the right place is to place the propeller diameter on the drawing and see if the tips hit the fuselage side.

[wellsprop]

Agreed, from the profile, there's a clear change in the angle of the trailing edge about 1/3 from root to tip. I don't think the engine or undercarriage positions would have changed for a new wing.

[fastterry]

Looking in my ancient copy of Aircraft of the RAF by Owen Thetford, he quotes spans as 56' 6'' for Mk 1 and 57' 6' for the Mk T.21. Fuselage length is the same for both at 42' 3''. Can't help with the rest.

TRF

[wellsprop]

I've just got myself a copy of the servicing manual for the XIX.

 

It quotes the wingspan as 56' 5". However, this cannot be correct for the metal wing. It goes on to quote the wing area of the metal wing as 440 ft sq, whereas the wood wing is 410 ft sq. The metal wing is clearly more tapered in profile, therefore, it must be longer too, in order to have a greater area than the wood wing.

 

 

Looking at the information regarding wing ribs and positions, it is clear the metal wing IS greater in span. It has 23 ribs, whereas the wood wing has 21. When these two images are overlaid, it is clear the metal wing has a greater span.

 

 

 

[Dave Swindell]

2 hours ago, wellsprop said:

Looking at the information regarding wing ribs and positions, it is clear the metal wing IS greater in span. It has 23 ribs, whereas the wood wing has 21. When these two images are overlaid, it is clear the metal wing has a greater span.

Whilst your conclusion may be correct, I'd be cautious of your reasoning.

The extra ribs don't necessarily mean increased span, as the wings are of completely different construction the rib stations aren't guaranteed to be the same spacing, it could be more ribs closer together on the same span.

The images you post also need to be taken with a pinch of salt - they're illustrations, not scale drawings or technical drawings

The purpose of the drawings is to show the relative position of the ribs and stations, unless you have technical information giving the dimensions between each rib or station you can't definitively draw conclusions as to overall dimensions. The drawings "may" be scaled, but there's no guarantee they are.

Having said that, they do illustrate the different shape/size tailplane as well...

[wellsprop]

@Dave Swindell yes, I am making the assumption that the rib spacing is the same (or similar). That said, I am now confident enough that I have found enough references to the metal wing being "series 2", and that they did indeed have an increased span - which would make sense as the wing area increases, despite the wings tapering more, they do however appear broader in chord slightly.

[wellsprop]

Quick update, I got a plan view of an Anson Mk I and threw it in my CAD software, having scaled it to a 56'6" wingspan.

 

I measured the engine centres and they came in (near enough) at a scale measurement of 6' 10" (engine centre to fuselage centreline). I.e. the profile of the Mk I Anson I have (when scaled to a wingspan of 56'6" has the correct engine centre measurements - inline with the servicing document I have).

 

I compared this profile with the Aeroplane Magazine profile (see my first post/image) of the late Mk Anson with the metal wing - the engine centres of the late mark Anson were inboard of the Mk I. I resized the late mark Anson to have a wingspan of 57'6", and the engine centres moved to the correct position. HOWEVER, the fuselage length was then too great.

 

What this means;

• The later Ansons with the metal wing (XIX, 20, 21, 22), have a wing span of 57'6" - as noted in the Aeroplane Magazine Database Article and BAE SYSTEMS' website.
• The Aeroplane Magazine Database drawing has the correct fuselage length, but the wrong wingspan. The profile has been drawn to the wingspan of the wood wing, but showing the later metal wing.

[rossm]

The Putnam Avro book has Mks 11, 12 and 19 srs 1 (all wooden wings) as 56ft6in span 42ft3 length and Mks 18, 18C, 19 srs 2, 20, 21 and 22 as 57ft6in span ans 42ft3in length.

 

Interestingly the wing area is given as 463 sq ft for the wood wing and 440 sq ft for the metal one, presumably due to the sharper taper.

[wellsprop]

14 hours ago, rossm said:

The Putnam Avro book has Mks 11, 12 and 19 srs 1 (all wooden wings) as 56ft6in span 42ft3 length and Mks 18, 18C, 19 srs 2, 20, 21 and 22 as 57ft6in span ans 42ft3in length.

 

Interestingly the wing area is given as 463 sq ft for the wood wing and 440 sq ft for the metal one, presumably due to the sharper taper.

 

Thanks Ross

 

That's strange it gives the wood wing as 463 qs ft, whereas the Avro servicing manual gives it as 410. But then again, the Avro servicing manual also fails to mention the greater wingspan of the metal wing.

[Graham Boak]

You have plans of the aircraft giving the chord, taper ratio and span.  You tell us what wing areas you are getting.  I'm quite happy to accept the odd typo - after all the Defiant Mk.II manual quotes the same length as the Mk.I so these things do happen.