Author Topic: D.H.88 Comet Follow-Ons  (Read 10780 times)

Offline Robomog

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Re: D.H.88 Comet Follow-Ons
« Reply #25 on: July 14, 2021, 05:26:48 PM »
Just when you think things couldn't get any better you produce this one !

A beautiful bit of streamlined goodness   :-* :-*

Mog
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Offline apophenia

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Re: D.H.88 Comet Follow-Ons
« Reply #26 on: July 15, 2021, 02:29:11 AM »
Cheers Mog! I've got at least one more 'D.H.88 Comet Follow-On' coming. This time, a little bit more realistic  :D
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Offline finsrin

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Re: D.H.88 Comet Follow-Ons
« Reply #27 on: July 15, 2021, 02:46:34 PM »
So many fine variations  :smiley:    Wonder if prone pilot design would be faster  ???     Brian should be here to see the ultra sleek spats.

Offline GTX_Admin

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Re: D.H.88 Comet Follow-Ons
« Reply #28 on: July 16, 2021, 03:15:37 AM »
Wonder if prone pilot design would be faster

Probably not as the DH.88 was already pretty sleek.

There's an interesting story on the supposed plan to use the DH.88 asa bomber of sorts int he most recent edition of Aeroplane:

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Offline robunos

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Re: D.H.88 Comet Follow-Ons
« Reply #29 on: July 16, 2021, 03:48:05 AM »
As promised, a racer ... sorta.


Ooohh, that looks so good . . . trouble is, someone's going to want to turn it into fighter . . .   ;)       ;D


cheers,
Robin.
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Offline apophenia

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Re: D.H.88 Comet Follow-Ons
« Reply #30 on: July 16, 2021, 08:26:54 AM »
... Brian should be here to see the ultra sleek spats...

He should ... Brian is very much missed  :(   Those 'semi-retractable speed spats' were my homage to the unforgettable BdB.

... Wonder if prone pilot design would be faster...

As Greg said, probably no faster than the D.H.88 Comet itself. My idea was that the High Speed Experimental Flight would want a prone-pilot trainer in case that avenue was explored for higher-speed service machines - so, ultimately, different prone-pilot service airframes with much more powerful engines.

Ooohh, that looks so good . . . trouble is, someone's going to want to turn it into fighter . . .

Cheers Robin! Mind you, I wouldn't want the job of puzzling through how to fit eight Brownings into that wing  :o
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Offline Robomog

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Re: D.H.88 Comet Follow-Ons
« Reply #31 on: July 16, 2021, 10:38:20 AM »
Bung em in the nose Mosquito style  ???

Mog
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Re: D.H.88 Comet Follow-Ons
« Reply #32 on: July 17, 2021, 01:51:28 AM »
The nose was largely fuel:

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Offline Robomog

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Re: D.H.88 Comet Follow-Ons
« Reply #33 on: July 17, 2021, 05:23:40 AM »
Hummm maybe not :-[

Even if you take one tank out the guns will still be pretty close to the other one.

It's one huge flying fuel tank.

Gondolas under the wing Gladiator style ?   But then there will be increased drag

Tricky   :icon_bofh:   ;D

Mog
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« Last Edit: July 17, 2021, 05:25:12 AM by Robomog »
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Offline robunos

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Re: D.H.88 Comet Follow-Ons
« Reply #34 on: July 17, 2021, 05:59:01 AM »
Bung em in the nose Mosquito style  ???

Mog
>^-.-^<


I was referring to the Griffon engined version . . .   ;)


cheers,
Robin.
By the pricking of my thumbs, Something Whiff-y this way comes . . .

Offline Robomog

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Re: D.H.88 Comet Follow-Ons
« Reply #35 on: July 17, 2021, 09:07:36 AM »
Yep realised that now  :-[ 

My gondola  suggestion still stands or a fuselage gun pack but  trade off against more drag and limited space,,  it seems everything you come up with means you loose a fuel tank  :-\

This whiffy stuff  makes my brain hurt  :icon_zombie:

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Offline apophenia

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Re: D.H.88 Comet Follow-Ons
« Reply #36 on: July 17, 2021, 10:57:58 AM »
The nose was largely fuel...

I hadn't realized that there was another, 20 Imp Gal. tank behind the navigator. Cool!

Next installment ...
________________________________________________________________

It is often assumed that the D.H.118 Dragonet was simply a monoplane derivative of the D.H.90 Dragonfly. There were certainly strong family resemblances and D.H.118 did did adopt an unmodified D.H.90 empennage. But, in all other respects, the Dragonet was unrelated to the slightly larger Dragonfly. Indeed, the aircraft with the most in common with the D.H.118 was the D.H.88 Comet racer.

For the D.H.118, Comet wings and nacelles were adopted almost without change. [1] The D.H.118 Dragonet fuselage strongly resembled a shortened Dragonfly unit without the top wing attachment points. However, the interior was quite different - being only a 4-seater. The rear 'bench' seat was really the upholstered top of the main fuel tank (the Comet wings lacking spare for fuel). Somewhat awkwardly, baggage stowage was aft of that tank and accessed through a starboard-side door.

With its thin, monoplane wing and Gipsy Six engines, the D.H.118 Dragonet was a much faster aeroplane than the D.H.90 Dragonfly biplane. Doubtless there would have been a private market for the speedy D.H.118 Dragonet had the War not intervened...

________________________________

[1] There was some local structural strengthening and the cowlings were new - being much more accessible than the older Comet designs.


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Re: D.H.88 Comet Follow-Ons
« Reply #37 on: July 18, 2021, 01:11:19 AM »
Maybe something akin to the Blenheim's belly gun pack:





« Last Edit: July 18, 2021, 01:13:55 AM by GTX_Admin »
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Offline Robomog

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Re: D.H.88 Comet Follow-Ons
« Reply #38 on: July 18, 2021, 08:34:47 AM »
That was what came to my mind but you would have to lose the  rear seat or fuel tank to get it in  ;)

Mog
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Offline apophenia

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Re: D.H.88 Comet Follow-Ons
« Reply #39 on: July 18, 2021, 10:33:50 AM »
Alternatively, underwing gun pods? There's a few contemporary fighters with that arrangement - the Caudron light fighters and Koolhoven F.K.58 come to mind.
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Re: D.H.88 Comet Follow-Ons
« Reply #40 on: July 19, 2021, 01:56:10 AM »
Alternatively, underwing gun pods? There's a few contemporary fighters with that arrangement - the Caudron light fighters and Koolhoven F.K.58 come to mind.


Not sure if the wing would have allowed for though I suppose one might be able to do something akin to those used on the Gloster Gladiator, though even these still needed ammunition to get to them via the wing:



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Re: D.H.88 Comet Follow-Ons
« Reply #41 on: July 19, 2021, 02:58:56 AM »
Not sure if the Blenheim unpacks were fully self contained:

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Offline jcf

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Re: D.H.88 Comet Follow-Ons
« Reply #42 on: July 19, 2021, 03:55:04 AM »
TBH, I can see Park Place being closed down and 're-developed' . . . If it was up to me, there'd be a statue of Webster on the Bridge, opposite Sister Dora, instead of the useless fountain, or if not there, in front of the Town Hall and Library, with John Carless VC, and the Hippo, and a replica S.5 on the roundabout at the junction of Lichfield Road and Mellish Road, which isn't far from his birthplace in Borneo Street, similar to the E.28/39 replica in Lutterworth. Or even an 'artistic' design like the Spitfire Island in Castle Bromwich, Birmingham . . .


cheers,
Robin.

They might be willing to consider some of that if you promise to pay for it.  ;D

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Offline jcf

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Re: D.H.88 Comet Follow-Ons
« Reply #43 on: July 19, 2021, 04:13:22 AM »
Based on period, why would a Comet fighter even have eight Brownings? It would predate
the requirement.

One thing that would be needed is to swap the position of the cockpit and the center fuel
tank. Reduce the size of the fwd. fuel tank to allow for the ammo tanks and mounts of a
cluster of four Brownings, or perhaps two .303 Browning and two Vickers .50 experimental
aircraft guns.
“Conspiracy theory’s got to be simple.
Sense doesn’t come into it. People are
more scared of how complicated shit
actually is than they ever are about
whatever’s supposed to be behind the
conspiracy.”
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Offline apophenia

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Re: D.H.88 Comet Follow-Ons
« Reply #44 on: July 19, 2021, 10:55:35 AM »
Based on its experiences with the D.H.92 Dragonfly, de Havilland Aircraft made no assumptions about the RAF buying their new D.H.118 Dragonet. [1] Still, it was clear that a potential military market existed for the new design. It was decided to adapt a variant of the Dragonet for the military multi-engine training role. There were already rumours about a forming a new training scheme akin to the 1917-18 Royal Flying Corps Canada (RFC Canada) organization. Orders were already coming in for increasing numbers of D.H.83C Tiger Moth trainers in Canada.

The D.H.118M Dragonet (Military) - as it was named - was to be be a dedicated pilot trainer. In most respects, the airframe was unchanged but the forward fuselage and cockpit areas were completely different. In place of four luxury seats were dual-control positions for a pilot-trainee and an instructor. This cockpit was covered by a new sliding-hood for ease of access (and emergency egress). Behind the side-by-side trainee/instructor positions was a single 'jump seat' positioned above the fuselage fuel tank. [2]

Although designed to British specifications, it was intended that any production military variants would be built by DH's Canadian subsidiary, De Havilland Aircraft of Canada Ltd. The parent company would supply example airframes, some fittings, and other de Havilland subsidiaries would supply powerplants and propellers. These components would be shipped to Downsview for final assembly by 'De Havilland Canada'. It all seemed to make perfect sense. But, the future would reveal that de Havilland Aircraft planners had made two fatal miscalculations.

The lesser of the gaffs involved that rear 'jump seat'. The concept of carrying a training observer was sound - and made the D.H.118(M) more competitive with larger-capacity trainers like the Airspeed Oxford. However, in the D.H.118(M), that observer had little chance of successfully escaping the aircraft in an airborne emergency. In effect, de Havilland had created an oversized baggage compartment in an aircraft which had no need for stowage.

More serious was funding. If an aircraft like the D.H.118M Dragonet (Military) was found to be needed in Canada, who would pay for it? De Havilland brass assumed that superior design was why Canada had chosen the D.H.83C Tiger Moth over a domestic trainer - the Fleet Finch. In fact, the deciding factor for Canada was that D.H.83Cs were paid for by Britain. De Havilland was about to discover that Ottawa would be no more willing to incure costs buying D.H.118(M)s when Britain was willing to foot the bill for Oxfords. There would be no orders forthcoming for the otherwise excellent D.H.118M Dragonet (Military). [3]

________________________________

[1] The travails of working with the Air Ministry on the D.H.93 Don also weighed upon DH head office. Other than elementary trainers, de Havilland had been ignoring most RAF Requirements. The ever-changing demands on the D.H.93 was suggesting that tendering submissions might not be worth the candle.

[2] This 'seat' was more padding on top and forward of the L-shaped fuel tank.

[3] De Havilland got the last laugh. In 1939, 150 Airspeed Oxford were built by DH at Hatfield. In June, 1940, de Havilland bought the remaining shares of Airspeed Limited and Airspeed became a wholly-owned DH subsidiary.
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Offline GTX_Admin

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Re: D.H.88 Comet Follow-Ons
« Reply #45 on: July 20, 2021, 02:09:38 AM »
Based on period, why would a Comet fighter even have eight Brownings? It would predate
the requirement.

One thing that would be needed is to swap the position of the cockpit and the center fuel
tank. Reduce the size of the fwd. fuel tank to allow for the ammo tanks and mounts of a
cluster of four Brownings, or perhaps two .303 Browning and two Vickers .50 experimental
aircraft guns.


I was thinking of something like that or even 1 20mm cannon and a pair of .303s.  One could maybe halve the size of the nose fuel tank to accomodate.
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Offline apophenia

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Re: D.H.88 Comet Follow-Ons
« Reply #46 on: July 20, 2021, 10:04:36 AM »
I was thinking of something like that or even 1 20mm cannon and a pair of .303s.  One could maybe halve the size of the nose fuel tank to accomodate.

Does it have to be a two-seater? A single-seat evolution would certainly simplify fuel tank placement.

On the 20 mm, its quite a while before the HS.404 is ready (read: reliable enough) for action. Meanwhile the Luftwaffe was using Oerlikon FFs firing 20 x 80RB and the RN had Oerlikon Type S guns with 20 x 110RB.

Three options occur for getting a 20 mm cannon into RAF service in the mid-/late '30s:

- 1) Adopt the Oerlikon FF in the form of the Hispano-Suiza HS.9 (possibly buying now-surplus French tooling);
- 2) Re-barrel Jon's Vickers .5-inch gun to take a 'necked' Vickers 12.7 x 81 round with the Oerlikon shell;
- 3) Enlarge the Vickers .5 inch aircraft gun to be able to accommodate the RN's Oerlikon 20 x 110RB.

Or, a more out-there possibility - develop the bigger Vickers .5 inch Class D (aka HV) for aircraft use (probably by substituting a bunch of aluminum alloy for steel). The 12.7 x 120SR cartridge already packs a punch. But my favorite idea is turning the Vickers HD into an 'Imperial Cannon' - necking the cartridge to 19.1 x 120SR to create a .75-inch aircraft gun  :smiley:
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Offline GTX_Admin

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Re: D.H.88 Comet Follow-Ons
« Reply #47 on: July 21, 2021, 01:54:23 AM »
I like your ideas re the 20mm gun, though the more I think of it, the 12.7mm option is doable too.  I was thinking of this as being about a 1935/36 aircraft and perhaps a long endurance/range fighter - not quite a Zerstörer but maybe something on the path towards.  If one thinks as the Spitfire/Hurricane as short range interceptors this is the long-range bomber escort or perhaps just long endurance standing patrols.  Either might want the second pilot or perhaps the second becomes a radio operator/nav?
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Offline apophenia

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Re: D.H.88 Comet Follow-Ons
« Reply #48 on: July 22, 2021, 07:33:08 AM »
I like your ideas re the 20mm gun, though the more I think of it, the 12.7mm option is doable too.  I was thinking of this as being about a 1935/36 aircraft and perhaps a long endurance/range fighter - not quite a Zerstörer but maybe something on the path towards.  If one thinks as the Spitfire/Hurricane as short range interceptors this is the long-range bomber escort or perhaps just long endurance standing patrols.  Either might want the second pilot or perhaps the second becomes a radio operator/nav?

Yes, the Vickers .5-inch would be the quickest way to go in 1935-36. On crewing, one possibility would be to have a mix of variants.

For long patrols, navigation could be handled by a 2-seater with .303s only. The rest of the formation would then be single-seaters armed with both .303s and the heavier guns.

For bomber-escort, the 'Big Friends' from Bomber Command could provide the nav. (Although, maybe a 2-seater fighter in the mix to provide for a formation wireless operator?)

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Offline apophenia

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Re: D.H.88 Comet Follow-Ons
« Reply #49 on: July 22, 2021, 07:39:10 AM »
My take on Comet fighters ...
___________________________

The de Havilland D.H.88F Comet Fighter was considered an interim long-range fighter. Inspired, at least in part, by the German remilitarization of the Rhineland, the RAF's Comet Fighters spent most of their careers on over-water defensive sweeps.

Bottom Show here on armaments trials in early 1938, Comet Fighter AX863 [1] has protective doped patches over the muzzle ports for its .303-inch guns but not its .5-inch Vickers Mk.V ports. This reinforces suggestions that AX863 was employed on trials of experimental explosive rounds (which were technically forbidden by the 1868 Saint Petersburg Declaration). Note that AX863 sports the  'rear light' modification (to improve the pilots aft view).

As its name suggests, the Comet Fighter was a straightforward adaptation of the D.H.88 Comet racer. The reputation of that racer added some prestige to the RAF operating the D.H.88F but the Comet Fighter was effectively a proof-of-concept intended to be replaced by a purpose-made long-range fighter design. That design emerged as the D.H.128 Meteorite. [2]

The D.H.128 was very similar to the D.H.88F in construction but had a slightly longer rear fuselage and reinforced wings. The powerplants were twin de Havilland Gipsy King Series I-DCs. These inverted V-12s were based on the Gipsy Twelve engines Frank Halford was designing for the Albatross airliner. To speed D.H.128 development, Sir Frank abandoned reversed cooling in favour to simpler direct-cooling (hence the 'DC' suffix). [3] The Series I-DC engines also had a higher thrust-line than the reverse-cooled types.

Compared with the D.H.88F, the obvious difference in the D.H.128 design was its forward-placed cockpit. This meant that the armament of four 20mm Oerlikon shell guns could be placed over the aircraft's centre-of-gravity (as could the fuel tanks). Blast-tubes very arranged alongside the cockpit. The view from the forward-positioned cockpit was judged exemplary. Opinion of that cockpit's sliding canopy was much less complimentary. Similar to the hood design which would emerge for the Fox Moth biplane, service pilots found this canopy too small and overly constraining. It was often left open in flight despite being deleterious to this fighter's performance.

Top De Havilland's D.H.128 Meteorite demonstrator. This aircraft was retained at Hatfield by permission of the Air Ministry. The B Class registration E.9. was applied (being inherited from the D.H.84 Dragon prototype when that transport received its civil registration G-ACAN). Upon request, E.9. was delivered to the RAF in early September 1939. This aircraft was lost off of Narvik, Norway on 01 June 1940.

______________________________________________________________________

[1] The RW AX863 was an impressed D.H.84 Dragon I transport.

[2] De Havilland had assigned the name'Dragonstar' to its D.H.124. This name was rejected by the Air Ministry which chose Meteorite as the aircraft's service name.

[3] Shifting to direct-cooling increased drag but reduced both weight and the frontal area of the cowlings. In the initial D.H.88F drawings, reverse-cooling was provided by 'elephant ear' intakes to either side of the nacelle. This also pushed the engines forward, demanding an even longer extension to the rear fuselage and more greatly enlarged tail surfaces. All this could be scaled back by adopting direct-cooling.
Froglord: "... amphibious doom descends ... approach the alter and swear your allegiance to the swamp."