Hawker Demon fuselage top change

[Graham Boak]

I'm working my way through the Putnam "Armament of British Aircraft 1909-1939" - somewhat belatedly I admit - and have come across a number of interesting snippets, but this is the best so far. The Hawker Demon has the rear fuselage reduced in height compared with the Hart. "The more slender fuselage which resulted was one of several features which distinguish the Demon from other Hart variants." I hadn't noticed that before - has anyone else?

The author, who "flew in Demons at every opportunity" goes on to say that the top of the fuselage of the Hector "displayed a much larger flat surface of fuselage" than even the Demon.

The Hind (and hence the Australian Demon) had the same rear fuselage as the Hart, despite the change in the gun position.

Comments? John?

[Andrew Jones]

Presumably this refers to the lowered area where the gun ring was fitted on the Demon, otherwise the two fuselages appear identical. this lowered area was even more pronounced on the later " turret Demon ".

Andrew

[Graham Boak]

No, not the gunner's position itself. This is referring to the rear fuselage behind the gunner's position. Immediately behind, I'd say. There seems to be a distinct step down front to aft of the cockpit compared to more of a continuous line on the Hart.

I'd suggest that this photo, and others of the restored A1-8, does show just such a flattening of the top of the fuselage. However, the author above states that this shouldn't apply to the Australian Demon or the Hind. So he isn't right there - but then I don't suppose he ever saw an Australian Demon. The Hind does seem to follow the same line as the Hart.

[Aidrian]

Looks like a possibility based on those photos - there definitely a difference in the look, which suggests the top decking behind the gunner's seat might be lower. However the coaming behind the pilots seat appears a different shape on the Demon and perhaps might be a little taller even after allowing for the cutaway?

I will now retreat to the study and draw squiggly red lines over every photo I can find then post the results

Edited July 14, 2014 by Aidrian

[Graham Boak]

If you look in the MMP book on the Hart family, this includes a print of a Hawker drawing showing a Demon fuselage cutaway (p206) which shows this lowered fuselage decking more clearly. Yes I have had the book for a while and no I hadn't noticed it before. This book does also show that the Australian Demon, often regarded not a "proper" Demon but as a Hind with an extra gun, has the same lowered fuselage and is thus better described as a Demon with a Hind engine. The drawings in the book do not reflect this - so it's not just me (and you) missing something obvious. I think it's a matter of "everyone knows the lines of the Hart family fuselage" without actually looking closely for differences.

[John Aero]

Sorry I'm late to the discussion but I've been away in Norway. (archaeological dig looking for a rare Luftwaffe bicycle )

I don't think that there is a difference in the rear fuselage heights. A line drawn along the slope of the rear fuselage top normally touches just below the lip of the pilots front coaming. The rear edge of the pilots cockpit on types with the cutaway gun ring is higher and squarer as it often incorporates a windscreen. The high ring mount types also have a cutaway portion just aft of the gun ring which the Demon doesn't have but the Hind does and the Hector also incorporates this, but it appears to be larger. Most of these differences are in my opinion are confined to the plywood covered area with most of the formers aft being standard.

John

[Graham Boak]

Sorry John, but it think the step you describe in front of the pilot is a red herring. If you put a french curve on the fuselage top, you can see that the Hart line is a single continuous shape before and aft of the cockpit. For the Demon this is not the case, there is a distinct step down. How much this reduced height is washed out along the rear fuselage is difficult to judge.

Judging from photos: Andrew and I think the step is there.

Judging from informed contemporary observers: HF King states that the height is reduced.

Judging from official drawings: MMS Hart family book includes a Hawker company drawing which shows a step.

[John Aero]

It was late last night when I looked at mainly old photos in the Mushroom book. However I decided to look at my own material and H King is correct. Fortunately I used the same Hawker side drawing as the basis for my 1/48th Demon.

John

For comparison... Don't be confused by the wheel sizes, Demon 19's and Hind 15's.

[Graham Boak]

Thanks, though whether these photos would move anyone from an entrenched view is perhaps debatable! Now (or rather, sometime) to see which 1/72 kits have enough depth in the rear fuselage to sand down to a more representative shape.

[Old Man]

So let me ask as a simple modeller, gentlemen....

If I do a Demon now (and yes, I am thinking of soon doing a fairly quick build of an old Aeroclub 1/72 Demon), am I supposed to sand flat a portion of the turtle-back directly behind the gun ring (leaving a sort of triangular facet), or am I supposed to sand down the whole turtleback so it rises from tail to ring at a lesser angle?

[Work In Progress]

Well, that's fascinating. I have been interested in the Hart family for four decades, and have never noticed that before, even when looking at the same two aircraft at Old Warden on the same day (though not side by side: the Hind was in the hangar and the Demon out in the sunshine).

But now I have seen it, I can't miss it.

Just goes to show that if you're not measuring things it is human nature to have your brain fill in what it expects to see.

Old Man, it is a continuously curved deck.

Edited July 22, 2014 by Work In Progress

[Graham Boak]

King's book does include a copy of a very similar Hawker drawing of the Hart; those with scanners and appropriate software could resize and overlay these views, but I lack the latter.

The question then arises as to why this modified fuselage wasn't seen on other variants after the Demon, which may be linked to production in other factories of the Hawker Siddeley empire but I suspect it isn't that easy. We may be a few decades too late for an easy answer. That the Hector was different again doesn't seem too obvious from what I've looked at, but King may have been referring to the top immediately aft of the gunner rather than the rear fuselage as a whole.

[John Aero]

I've been busy with other things such as building maintenance and business in Dorset, This post has been bugging me as I should have picked up on things sooner.

The problem is with so many drawings around it's so easy to see the areas you're looking for and when I was doing my recent Demon I was concerned over the shape of the rear decking of the restored aeroplane and when I checked period photos and confirmed they were right, I just assumed that the Demon had done away with the flat sculpted depression aft of the gun ring (this allows clearance for the gun support tube of the Hawker hi-speed mount when fully depressed) as this was the first type with the inclined gun mount. The next type, the Hind, revived this sculpted area first seen on the Hart.

H.F King is right in that there are differences in the top decks aft of the gun but his description of them being flatter, is in my opinion a little misleading.

However here are my findings.

It's easy to assume that the first Hart fighters as the six conversions were first known that they were Harts with one front gun and the revised inclined gun ring on a pretty standard fuselage.

On checking my own collection photo of Hart fighter K1953 it's clear that the turtle deck is also different by lacking the cutout area. However the whole new rear decking is not flatter but just lower. I assume this reshaping was an attempt at giving a wider field of fire but showed little advantage and was not incorporated on any other variants. By scanning and scaling the suggested Hawker drawings and matching the structures I have calculated that the Demon rear decking is 3" lower than that of the Hart/ Hind, both of which have the higher stringered decking and the flat sculpted area.

So the Demon rear fuselage is lower and has a gentler taper back to the tail. The cross sections just aft of the gun mount are similar with that of the Demon being pulled in tighter with a slightly flatter peak.

The Hector which was basically a Hind variant has a similar rear top decking but it requires greater clearance for the Barr and Stroud modified cranked gun support tube and so this flat recessed area is slightly longer and the top deck aft of this is the same as the Hind.

The Australian Demon has the lower rear fuselage besides having the Hind type operational fittings.

John