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Radpoe Spitfire

Gladiators into Gauntlets

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IIRC the difference in wingspan (some 82mm per wing, thus 1.14mm in 1/72 scale) is caused by different rib spacing - in Gauntlet you have 35 fields of almost equal size (5 of them within cabane and 15 in each wing half), while in Gladiator there are 32 similar fields (although 8 of them forming much wider cabane part) plus 8 narrow ones (with no auxiliary rib noses inside). Moreover the ailerons are much longer - the distance between inner ends is roughly 19 ft for Gauntlet and 17 ft for the Gladiator. 

And when talking about the stagger you must remember that not all Gladiators are the same here. The wings are staggered 27.2" in Mk.I and 29.5" in Mk.II and Sea Gladiator. Similarly the distance between wings is 63.8" for Mk.I and 62.6" for all other variants. Unfortunately most kit designers forget about it...

BTW. I'm still not sure whether concerning the Gladiator we should call those underwing aerodynamical devices "flaps" - with 90 degree opening angle and application for reducing the speed before landing (decreasing the attack angle simultanously) they rather look like proper airbrakes, don't they?

Cheers

Michael

Edited by KRK4m
flaps/airbrakes caption added

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You are of course free to call them what you like, however this kind of all-or-nothing operation was entirely common for the period and they were (and still are) called flaps.  This is because they do not just add drag but more importantly also add lift, acting simply as a crude form of camber.  Had this not been true, stalling speeds would not change, which they do.  If you want another contemporary example, the Spitfire.  Air brakes, if properly designed and placed, do not add lift or indeed induce any kind of pitch change.  Hence the difference in terms for different roles.

 

I must admit not knowing about this change in stagger, but am puzzled as to why this would be.  An increase of over 2in in stagger suggests that the cg had been moved forward, which may have been true with the Mk.IIs engine and three-blade prop, but would be just the opposite with the arrester hook on the Sea G.  Particularly as the props were interchangeable on the Sea Gladiator (and therefore presumably on the others, had anyone thought to try).  It must have been an interesting exercise, but it was carried out onboard HMS Eagle in the Mediterranean where maximum speed was considered less important than take-off run and initial climb.

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8 hours ago, Graham Boak said:

You are of course free to call them what you like, however this kind of all-or-nothing operation was entirely common for the period and they were (and still are) called flaps.  This is because they do not just add drag but more importantly also add lift, acting simply as a crude form of camber.  Had this not been true, stalling speeds would not change, which they do.  If you want another contemporary example, the Spitfire.  Air brakes, if properly designed and placed, do not add lift or indeed induce any kind of pitch change.  Hence the difference in terms for different roles.

Of course, Graham, the theory looks exactly like you described it above. And I also call them "flaps", following the designer's idea. 

Unfortunately I wasn't able to fly the Gladiator myself but - following the pilot's notes of H.A. Taylor concerning the K7965 he had flown on 3rd November 1939 - applying the "flaps" on approach caused so much drag that (instead of increasing pitch he was looking for) the nose went DOWN due to the abruptly decreased speed. There was some advantage of this action, however, as the nose-down attitude greatly improved the forward view that was useful for the first landing on the type in his career :)

Cheers

Michael

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I, too, would like to see a bit more evidence about a change of wing geometry (stagger) between marks.  Certainly not saying that it didn't happen, but first I've heard of it.

 

And forgive me, but I'm a bit amused by this phenomenon- a kit that is the answer to many (?) a person's dream, and it isn't hardly even in anybody's hands and it is, "How do I change it from what it is to something else?"  Mind you, I've tended that way for most of my (alleged) modelling life, so I'm not criticizing anybody.  Sure, I'd love a Gauntlet in 32nd (thanks to John Adams I did secure one- not built, of course- in 48th...) but man am I excited to have a Glad!  (In case anybody's still listening, I fell head-over-heels in love, as opposed to more generalized attraction, when I saw it flying at Shuttleworth in 1995.  A real 'gentleman's airplane'.  Not that I qualify...)

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As a performance man, it is easy to forget about pitching moment, so I'm glad in this case to have got a reference in first.  I must admit that I was thinking of Hawker's problems with the airbrake on the Hunter, which was very much a live consideration with the Hawk design when I was there.

 

Placement and operation of the control surfaces have to be carefully considered with pitch in mind.  Lowering the flaps results in a change of the airflow around the wing, which in this case moved the centre of lift aft, producing a nose-down pitch and an increase in drag, which by definition acts along the flight line of the aircraft.  Much as lift always acts vertically to the flight line.  Neither are strictly real, but a resolution of the true forces acting on the aircraft about the aerodynamic centre in order to make calculation easier - or, in the pre-supercomputer age, possible at all.  Throw in the weight acting at the cg, plus the thrust acting along the thrust line, and lo!  they all balance nicely.  If not, you get a pitching moment, and fhat's what a tailplane is for.  If it's just too big, get your eraser out and redesign.

 

I suspect that flaps were new to Folland and his team, and other design organisations in the early 30s, so a range of responses on various types will have appeared with the response left to the pilot.  Within a few years there will have been an issue of RAeS datasheets allowing informed predictions to supplement experience and word of mouth.  I'm a little surprised that HA Taylor expected a nose-up response, as to me a nose-down one is superficially more likely.  If of lesser extent.

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5 hours ago, Graham Boak said:

 I'm a little surprised that HA Taylor expected a nose-up response, as to me a nose-down one is superficially more likely.  If of lesser extent.

I wonder if he is the same HA Taylor who wrote one of the Putnam books, Fairey Aircraft Since 1915?

I suppose it depends what he'd been flying previously.  Perhaps a flapped high wing type? If his first experience of a Gladiator was in 1939 it seems likely he wasn't a front-line fighter pilot, at least not if he were in the UK, though I don't know where this flight took place.

However, regardless of geography by 1939 it seems unlikely that he'd be surprised by a nose down trim change if he had any experience of the Hurricane , Spitfire or Magister, all of which go nose down with flap. 

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6 minutes ago, Work In Progress said:

I wonder if he is the same HA Taylor who wrote one of the Putnam books, Fairey Aircraft Since 1915?

I suppose it depends what he'd been flying previously.  Perhaps a flapped high wing type? If his first experience of a Gladiator was in 1939 it seems likely he wasn't a front-line fighter pilot, at least not if he were in the UK, though I don't know where this flight took place.

However, regardless of geography by 1939 it seems unlikely that he'd be surprised by a nose down trim change if he had any experience of the Hurricane , Spitfire or Magister, all of which go nose down with flap. 

Flt Lt H A Taylor, who wrote Fairey Aircraft and several other works, flew in the ATA and latterly was an assistant test pilot for Supermarine on Spitfires during the war.

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On 11/29/2019 at 8:20 PM, Ossington said:

I'm sure that Chris Ellis converted the Airfix Gladiator into a Gauntlet in one of those 1970's modelling books that Airfix Magazine brought out. I haven't seen it for years, but I'll have a look.  

How to go advanced plastic modelling  113783-10000-24-pristine.jpginside the  front cover...spacer.png

 

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I believe that HA Taylor was for some time Technical Editor for Flight - he wrote a number of test flight articles and on technical matters.

 

I had both those books, but they've been passed on...

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2 hours ago, Procopius said:

Flt Lt H A Taylor, who wrote Fairey Aircraft and several other works, flew in the ATA and latterly was an assistant test pilot for Supermarine on Spitfires during the war.

Exactly - this Gladiator flight in November '39 was during his ATA duty and he was then (as he wrote there) used more to the light twins like Anson, Oxford and Blenheim.

Cheers

Michael

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As mentioned in post 15 there are very many differences between a Gauntlet and a Gladiator The transition from the SS.19 to the Gladiator via the Gauntlet, was a long and tedious one and one major change was the re mounting of the lower wing which was lower on the Gladiator than the Gauntlet and the wing gap increased. They were two very differing aeroplanes.  I used an AP fuselage drawing to make my fuselage. The wings are very different. Even the Gauntlet fuselage structure fabrication changed between the Mk.1 and the Mk.2.   I've not yet come across any reference to the differing wing stagger between the Gladiator Mk's but that doesn't mean I've been looking.  

 

This sort of thing did happen for instance on the Wapiti to change the C of G. on the Wapiti when the geared engine was fitted.   This was achieved by replacing the cabane struts by longer ones but retaining the main wing struts which were angled forwards to move the top wing forwards the correct amount, thus changing the centre of pressure of the two wings and the C of G.  Also the under-carriage radius rods were replaced by new shorter ones, thus projecting the axle forwards.  To quote Micheal Caine "not a lot of people know this". Two differing cabane strut reference numbers and strut dimensions in the rigging manual were the clue that made me think in a different way. Of course all the drawings don't show this...  Oh and the production Mk.V did not have a longer fuselage...

 

To prove this Gladiator C of G change you will need the relevant AP and rigging manuals and reference numbers of the struts and wires. If this is not so then it didn't happen.

 

John

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"As mentioned in post 15 there are very many differences between a Gauntlet and a Gladiator The transition from the SS.19 to the Gladiator via the Gauntlet, was a long and tedious one and one major change was the re mounting of the lower wing which was lower on the Gladiator than the Gauntlet and the wing gap increased. They were two very differing aeroplanes.  I used an AP fuselage drawing to make my fuselage. The wings are very different. Even the Gauntlet fuselage structure fabrication changed between the Mk.1 and the Mk.2.   I've not yet come across any reference to the differing wing stagger between the Gladiator Mk's but that doesn't mean I've been looking.  

 

This sort of thing did happen for instance on the Wapiti to change the C of G. on the Wapiti when the geared engine was fitted.   This was achieved by replacing the cabane struts by longer ones but retaining the main wing struts which were angled forwards to move the top wing forwards the correct amount, thus changing the centre of pressure of the two wings and the C of G.  Also the under-carriage radius rods were replaced by new shorter ones, thus projecting the axle forwards.  To quote Micheal Caine "not a lot of people know this". Two differing cabane strut reference numbers and strut dimensions in the rigging manual were the clue that made me think in a different way. Of course all the drawings don't show this...  Oh and the production Mk.V did not have a longer fuselage...

 

To prove this Gladiator C of G change you will need the relevant AP and rigging manuals and reference numbers of the struts and wires. If this is not so then it didn't happen.

 

John"

 

 

"I must admit not knowing about this change in stagger, but am puzzled as to why this would be.  An increase of over 2in in stagger suggests that the cg had been moved forward, which may have been true with the Mk.IIs engine and three-blade prop, but would be just the opposite with the arrester hook on the Sea G.  Particularly as the props were interchangeable on the Sea Gladiator (and therefore presumably on the others, had anyone thought to try).  It must have been an interesting exercise, but it was carried out onboard HMS Eagle in the Mediterranean where maximum speed was considered less important than take-off run and initial climb.

 

Graham"

 

Some 50+ years ago I was able to gain access to some Hawker and Gloster historical data. I still have the notes I took - photocopiers were very few and restricted in their use - scanners just a gleam in the designer's eye - so all notes were hand written in pencil.

 

I don't have the relevant APs but, attached below is a table I made, somewhat later, from some of the Gauntlet and Gladiator info I copied. IIRC, some, (more?), of this info is available in Francis Mason's 'Gloster Gladiator', MacDonald, circa mid 1960s. I no longer have a copy, but worth checking.

 

ed1caa37-7b77-4fcf-8b99-cdf87cf4872d.jpg

 

As noted, I estimated some of the Gauntlet info: the rest is what I copied from the files.

 

The 1.75" increased gap from the Gauntlet to the Gladiator, (mentioned by John), is shown, as is a 4" increase in stagger to accommodate the forward shift in the CofG due, mainly, to the heavier engine and its ancillaries.

 

There was also an increase in stagger, (mentioned by Michael in post 26), of another 4" from the Gladiator Mk.I to Mk.II, partly due to an increase in engine and ancillaries from 1,400 lb to 1,540 lb.

 

On the MK.I, the CofG was 6.55" aft of datum for wooden prop and 5.75" aft of datum for metal prop. The Cof G on the Mk.II with metal prop was at 5.8" aft of datum. 

 

No. 3 Sqn, RAAF, (and I presume other units), flew MK.II A/C fitted with wooden props. One pilot I interviewed said it was more agile than the A/C with the metal prop: I assume this was probably due to the rearward CofG shift.

 

I realise that I have taken this thread a long way from the original request and apologise for boring some readers. However, I thought the info might be of some interest to John and Graham in particular.

 

Peter M

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Interesting. I didn't know about the Gauntlet wings being narrower chord.

 

One apparent anomaly is that the wing gap data for the Gladiator II do not seem to tie up with the clearly visible lowering of the Gladiator lower wing on the fuselage, and the larger gap shown for the Gladiator I,  unless the Glad II cabanes were also shorter in the vertical. Is that possibly a transcription error?

Edited by Work In Progress

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Thank you for sharing the data table, there is much useful information there.

 

There is a whole encyclopedia hidden away on scribbled notes made by people like us. The internet devours and vomits out billions of gigs of totally pointless crap  every day, but just occasionally it gives us some small gems of knowledge which gleam in the garbage.

 

However as always, there is the question, where was the length change in the Gauntlet incorporated?  Unfortunately we no longer have airframes to measure and many detail production drawings and those who knew the detail are all gone. Small changes in an airframe where there is no physical thing such as a panel are very difficult to see.  Rest assured it's almost easier to build a model from scratch than try and convert.

 

John

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1 hour ago, Magpie22 said:

I don't have the relevant APs but, attached below is a table I made, somewhat later, from some of the Gauntlet and Gladiator info I copied. IIRC, some, (more?), of this info is available in Francis Mason's 'Gloster Gladiator', MacDonald, circa mid 1960s. I no longer have a copy, but worth checking.

The Gladiator info in the tables (and more), including the changes in gap and stagger, is available on pp.109-117 of Mason's 1964 Gladiator book.   There is also similar data for standard production Sea Gladiators with Mercury VIIIA or VIIIAS engines driving 3-blade Fairey propellers - but the entire C of G paragraph is missing from the Weights and Loadings section!  The increase in Nornal Aircraft Loaded Weight over a similarly fitted Gladiator II is 55.5lb.  Wing loading increases from 15.1 to 15.4 lb/sq ft and power loading from 6.76 to 6.92 lb/bhp.

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4 hours ago, Work In Progress said:

Interesting. I didn't know about the Gauntlet wings being narrower chord.

 

One apparent anomaly is that the wing gap data for the Gladiator II do not seem to tie up with the clearly visible lowering of the Gladiator lower wing on the fuselage, and the larger gap shown for the Gladiator I,  unless the Glad II cabanes were also shorter in the vertical. Is that possibly a transcription error?

Note that the figure for the Gauntlet chord is my estimate. I didn't find a definite figure for that. However, the wing span of Gauntlet is slightly greater than that of the Gladiator, but wing area is less. This would seem to indicate a lesser chord, unless the difference is due to smaller wing root TE cut outs on the Gladiator.

 

If the wing stagger was increased on the Gladiator II, the gap would be reduced and, yes, this would mean shorter cabane struts. 1.75" is hard to see on photos. I checked my original notes and the figures in the table are as I wrote them all those years ago. Perhaps @Seahawk could check his copy of Mason's book to see if I made a transcription error at that time.

 

Peter M

 

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Yes, if the wing areas are correct then the Glad mean chord must be greater. Though... 

Chord / Area is a bit of a minefield as it all depends which definitions are in use.

e.g. whether the projected area of the lower wing passing through the fuselage counted as wing area

and for chord, on a parallel-chord wing, whether we are talking about mean chord, or the actual distance between LE and TE along most of the length of the wing. 

 

With different cutouts and tip shapes you could have two aircraft with different mean chords but which have the same chord for modelling purposes ie. same distance between LE and TE.

 

Looking at your Glad numbers, and just running the arithmetic at face value, a 323 square foot wing with a span of 32'3' x2 (biplane) has a mean chord of 60.01 inches (323/32.25/2), but because of the cutouts and the rounded rather than rectangular tips, the structural chord over most of the wing must be more than that.  And of course the 323 square foot area quoted might be rounded slightly.

 

Wing gap: Thanks. It just felt just rather convenient and suspicious that a stagger increase would result in the wing gap going back to EXACTLY the Gauntlet figure, when it seems more likely to me that raking over the geometry of the existing-length cabane struts would have provided a different number. Either than or, perhaps more likely, they would have made new cabane struts to maintain the same top wing height, and same pilot field of view as the Mark I.

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A few points:

 

As the cabane struts will be picking up on fuselage frames, or at least strong points, a change in stagger will result in raking the struts?  Or moving the position of attachment?  And hence fuselage structure changes.

 

Wing Area will include that "hidden" inside the fuselage.  It may well be a nominal value from an early design iteration rather than the final true figure, although this probably isn't relevant here.

 

Chord is usually the mean chord worked out from the wing area and the span, but again this could be different on such "plank" wing designs.

 

 

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2 minutes ago, Graham Boak said:

Chord is usually the mean chord worked out from the wing area and the span, but again this could be different on such "plank" wing designs.

 

Exactly. What we need to know for modelling purposes is not the geometric mean chord but (on a mostly parallel chord wing) the distance between LE and TE: over that parallel chord expanse - what for the purposes of this discussion I'll call the structural chord.

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34 minutes ago, Work In Progress said:

 And of course the 323 square foot area quoted might be rounded slightly.

According to Mason, it isn't (or only to an immaterial degree): it comprises top wing 169.2 sq ft and bottom wing 153.8 sq ft.

 

54 minutes ago, Magpie22 said:

If the wing stagger was increased on the Gladiator II, the gap would be reduced and, yes, this would mean shorter cabane struts. 1.75" is hard to see on photos. I checked my original notes and the figures in the table are as I wrote them all those years ago. Perhaps @Seahawk could check his copy of Mason's book to see if I made a transcription error at that time.

According to Mason (and why should we trust his transcription any more than yours?), the stagger figures are Mk I 2' 3" +/- 1/8" v Mk.II 2' 5.5".  Gap figures are Mk.I 5' 3.75" v Mk.II 5' 2.75".  Your table includes measurements I don't see in Mason.

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There is, or at least was until recently, a flying Gauntlet in Finland.  It may be possible to obtain information from there.  Perhaps a rib length was noted?

 

For modelling level of accuracy in 1/72, differences in the wing tips will produce only a small (dare I say tiny) difference in areas and hence chords measured from them. It should be possible to obtain a value for the different root cutouts from a careful sketch, to much the same level.  Yes it is always better to get the real thing, but the problems with that are clear from the above.

 

 

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Ah, but this started with whopping-great 1/32 scale!  (Until Airfix ups the ante with 1/24... c'mon, lads!)

 

My gut feeling is that they might cheat and continue the trailing-edge line, ignoring the root notch.

 

If anybody would stand me a ticket to London, I'd be happy to get to the bottom of this?  (I was at the US National Archives a week or two ago, but while I saw one interesting folder about the Whirlwind (no, not the one that came to the US), I didn't happen to see anything about Gauntlets or Glads.)

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2 hours ago, gingerbob said:

Ah, but this started with whopping-great 1/32 scale!  (Until Airfix ups the ante with 1/24... c'mon, lads!)

 

My gut feeling is that they might cheat and continue the trailing-edge line, ignoring the root notch.

 

If anybody would stand me a ticket to London, I'd be happy to get to the bottom of this?  (I was at the US National Archives a week or two ago, but while I saw one interesting folder about the Whirlwind (no, not the one that came to the US), I didn't happen to see anything about Gauntlets or Glads.)

You will not bottom this out in London, but in Kotyka, Finland where the sole surviving Gauntlet is alive and well at Kymi airfield. Re-engined but otherwise a reliable source

 

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It goes well on a Leonides. The tail wheel looks like a it's off a 109. There's quite a good coverage of this one in the MMP book.

 

John

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