For those with a spare Magister

[Graham Boak]

I was looking on the Flypast website, Historic forum, and came across some photos of DG590, their Miles Hawk Major, and thought "what a nice thing to do with a Magister."  

https://forum.keypublishing.com/showthread.php?144846-Montrose-Air-Station-Heritage-Centre

 So I hauled out Volume 1 of Pete Amos's magnificent 3-volume history of Miles Aircraft, and started considering what to do.  The fairings for the undercarriage, of course, and the tailplane needs to be raised and the rear fuselage increased in height.  And a new fin and rudder.  It turns out that there are rather a few more oddities in the quoted dimensions of the two types, most of which can simply be ignored but others seem rather curious, as changes in the fuselage length are not visible in the photos.  Now I'm quite sure that if Peter didn't bottom the oddities, then no-one else is likely to, but I thought the photos nice enough, and the conversion tempting enough, to mention here.

[JWM]

This is for sure doable. I made two conversions from Frog Magister - to Speed Six and to Falcon

Cheers

J-W

 

[John_W]

Beautiful Builds J-W.

[Roger Holden]

On 20/04/2018 at 23:40, JWM said:

This is for sure doable. I made two conversions from Frog Magister - to Speed Six and to Falcon

 

 

As J-W alludes, you can build practically the entire pre-War Miles family from the Magister as they have a common wing and horizontal tail design. Really good drawings are in short supply, but the old Harborough 'Book of Miles Aircraft' from the 1940s is a starting point (from which the drawings in the Air-Britain book are taken).

[Graham Boak]

I'd love to believe that they had a common wing, and to be honest I do (with some qualifications) because it makes a lot of sense, but the quoted dimensions suggest otherwise.  Not that they are entirely consistent.  The early Hawk wing is 33ft/169 sq.ft, as is the M2F Hawk Major although the Aeroplane quotes 33ft 9in.  The M2P Hawk Major however is quoted initially at 34ft/172 sq.ft, but later at 174 sq.ft   Now an increase of 1 ft on a mean chord of 5.2 ft does suggest that 169 should go to 174.  BUT: the Magister is quoted at 2 inches shorter span than the HM but with 2 sq.ft larger wing area.   Miles was notoriously unconcerned about what he was as unnecessary bureaucracy and perhaps this extended to quoting basic dimensions?  

 

When it comes to length, a drawing of the Hawk Trainer shows 21ft.9in but it is quoted for the Hawk and Hawk Major as 24 ft, and the M14A Magister at 24ft 7½in. But where did the Magister grow?  And was it between the unsatisfactory M14 and the main production M14A or earlier?  There is a quote of the engine being moved forward 3½in, but it isn't clear when this was done.  It can be interpreted as between the M14 and M14A, but if done earlier than it might explain why the upper line of the nose seems to be flatter on the Magister than on the Hawk Major.  However the nose isn't obviously longer to the eye.  (It also might explain why the spin was worse on the M14 than the Hawk Major, or at least help.)   The cowling was revised for the M14, so a longer engine mounting might explain this too.  The rudder is different on the M14A, the M14 having the same as the Hawk Major, but doesn't seem to be any greater in maximum chord, certainly not 4 inches.

 

There's something fairly subtle going on but it certainly isn't clear just what.

 

Dimensions taken from Peter Amos's book.  As i said before, I'm quite sure that if Peter didn't bottom the oddities, then no-one else is likely to, but...

 

From the modelling point of view, the wing is probably best ignored unless you are going for the 33ft wing, but the fuselage requires cutting away to lower the tailplane and reduce the height of the rear fuselage before changing the fin and rudder.  This also needs doing for the M14 early production Magister - which includes those with the nice red and white colours, sadly. 

[Roger Holden]

When I said common wing, what I really meant was common outer mainplanes. If there was a span /area change, it would almost certainly have been within the constant chord centre-section. That was done by Percival, Lockheed, Fokker and doubtless a few other builders of wooden winged aircraft. Much cheaper than changing all those different wing rib jigs for the tapered outer portions.

 

Length dimensions of British aircraft seem notoriously unreliable......the kind of thing they gave the office boy to work out just before he drew the customary crude 3-view ga.  Did they include the correct production-standard spinner, prop, tail light, etc etc, or even ever have the plane in a tail-up attitude to make a proper measurement ? However, it sounds in this case that there clearly was some distinct length change at some point, maybe to improve the spinning characteristics. Best Magister ref I can recall is the Four Plus booklet, which I will dig out when I have time. 

 

The Air-Britain books are useful, but they give a historian/statistician's perspective, not an engineering one. Consequently their modelling value is relatively limited. 

[Graham Boak]

I'd forgotten about the 4+ book, but having dug it out I'm afraid that it casts no further light on the problem of the dimensions, or indeed on the precise relationship between the later Hawk Majors and the Maggie.  The 4+ book even quotes a wing area of 224.96 sq.ft, which is more than a trifle excessive!  It is greater than the span multiplied by the maximum chord (should be the mean chord).

 

Whilst agreeing with you generally about the AB books, it is fair to say that Peter Amos was a practising engineer, having been (amongst other things) a flight test engineer at Dunsfold at the same time as I was there.

 

PS   Would you agree with me that the Hawk Major's nose seems to droop down more than the Maggie's?  That could be compatible with the Maggie being slightly longer in the nose - though I can't see either a larger gap between wing and cowling, nor a longer cowling.

 

 

Edited April 24, 2018 by Graham Boak