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Ascoteer

A Brace of Dominies

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Ok. Got it. Still don't know what a servodyne is tho' :)

BTW. Super work that on the cockpits and wings.

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A Servodyne is like a hydraulic jack although it has a built in feed back system so it doesn't rely merely on hydraulic pressure in either the Up or Down lines to keep the flap in place. Ie it locks the position against any applied air load.

They were very much beloved of DeHavilland (who originally designed the 125).

When the 125 was on the drawing board it was intended to replace the DH Dove and so was designed to be simple to operate and maintain. Eg it had overwing refuelling, a 24V DC electrical system. I would surmise that, owing to the nature of the pressure hull/wing interface, fitting a pair of Flap jacks was too difficult so they went for single Servodyne.

Later variants of the 125 had a rotary hydraulic flap motor.

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Tuning now to the second model, this is a post-DAU (Dominie Avionics Upgrade) Dominie, specifically XS739 'F' as she was in 1997, since she was the first aircraft to wear the Black/White/ livery. 'F' was originally delivered as the 5th post-DAU aircraft in May 1996 in the old Red/White/Grey scheme; later during 1996 a decision was taken to re-paint all HQPTC (Headquarters Personnel and Training Command) aircraft in the new 'Lo-Level Hi-Viz' overall Gloss Black scheme. It was accepted that this could not be done with the Dominie since:

a. It would make the cabin unbearably hot during the summer months.

b. It would lead to overheating of the fuel in the wing tanks with associated venting ( venting being a common problem in the Dominie upon rotate in Summer at high fuel weights).

Thus the Black/White scheme was developed for the Dominie. Given the 'Mixed Profile' nature of Dominie operations (and the fact that Dominies were flown by qualified pilots and not students), it was further decided that the Dominies would be the last aircraft type to be repainted after the Hawks, Tucanos, Bulldogs and helicopters. 'F' was dispatched to the paint shop in early 1997 and was delivered in the April. At that time she sported a Playboy Bunny on both sides of the fin as well as just forward of the crew entry door. The painters having their little joke as an homage to Hugh Heffner's black DC9.

The fact that she was in Black/White was much appreciated the first few times we did land-aways at Newcastle! There was a rumour going around 55®Sqn at the time that subsequent Black/White aircraft would also sport odd logos connected with the colour scheme, eg the 2 Terrier dogs (Black and White Whisky), a blue star (Newcastle Brown Ale) – unfortunately (as ever) the 'Fun Detectors' came out and the Powers That Be at Cranwell stopped that idea in its tracks.

Turning to the kit, Airfix issued it in 1968 as a pre-DAU aircraft (unsurprisingly), when it was re-issued (in 2005?) with decals for post-DAU aircraft, the kit had not been updated. Quintessentially, if you wish to model a Black/White aircraft then it must be post-DAU. However, if you wish to model a Red/White/Grey aircraft then you need to check your photographic references/timescale. This is because 10 of the 11 post-DAU aircraft were initially delivered in the older scheme (the only one to be initially delivered in the later scheme was XS709 'M' (incidentally the oldest Dominie and now preserved at Cosford). Furthermore, through 1996 the Dominie Squadron at RAFC Cranwell was operating both pre- and post-DAU aircraft – the 7 pre-DAU aircraft being delivered to RAF Cosford as Ground Instructional Trainers in the latter part of that year.

I discussed the differences between pre- and post-DAU aircraft earlier. Essentially, there is a change in the cabin window arrangement from 6 windows on the port and 4 on the starboard to 4 on the port and 6 on the starboard. Additionally the post-DAU radome was 9" longer than before (and of a different profile) and the temperature bulb fitted on the starboard side of the nose (fitted in order to allow the new Air-Data computer to calculate TAS from IAS and Temperature) changed its shape and location.

I will try not to repeat myself (too much!) since I've already posted the basic techniques used.

Firstly I made up a template of the windows on the port side using Tamiya tape. This was then carefully transferred to the starboard fuselage half and the 2 extra windows marked in with an indelible marker.

DSCF0360.jpg

The 2 extra windows on the starboard were then carefully cut out and the 2 redundant ones on the port filled in with a piece of the kit glazing. Additionally the radome was removed flush with the forward edge of the nose-wheel bay. On the real aircraft this area is known as 'Frame 1' and is the bulkhead that carries the 'Sea Searcher' radar scanner (this area is un-pressurised, the pressure buylkhead being just forward of the windscreen).

DSCF0361.jpg

The radome halves were then cemented together and retained for later.

Edited by Ascoteer

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For this build I wanted to do something slightly different and have the crew access door in the open position (this is an inwards opening 'plug door' that rotates around the inside of the fuselage roof), this would entail scratch building the 'vestibule' area and detailing the flight deck and flight deck bulkhead.

Looking at the bulkhead included in the kit (part no. 9) it was apparent that this lacked the required depth to properly simulate the real thing. Additionally the bulkhead is solid and lacking the flight deck entry portal.

The component was 'beefed up' with a layer of 40thou Plastikard and the flightdeck entrance cut out.

DSCF0366.jpg

In this shot it looks a wee bit rough but it I did clean it up (honest Guv'nor!)

Work could now start on building the vestibule area. I started with a spare flight deck bulkhead and temporarily mounted it upside down in one of the fuselage halves just forward of the fore most window. From this, and with the flight deck bulkhead temporarily in place, it allowed me to measure up a floor from 30thou Platikard. This floor should be level with the bottom of the crew entry door opening. Note the door mounting lugs in the fuselage need to be cut away along with the lower portion of the front bulkhead rear mounting lugs in both fuselage halves.

The floor could then be cemented to the spare rear bulkhead, the cabin entry portal cut out and the vestibule area detailed.

DSCF0363.jpg

DSCF0364.jpg

DSCF0365.jpg

Note. Doing the rear bulk head this way is not strictly accurate since the Nav Instructor's station (on the port side) in actuality lies slightly abaft the Student Navigator's station (so the real bulkhead is actually 'stepped'). However I doubt it is noticeable in this scale, and doing it this way makes the sub-assembly far stronger.

Details were added using Plastikard, Microstrip, and stretched sprue. The first operation being to simulate the central well of the Dominie's floor by raising the floor line either sid with a double laminate of 40thou Plastikard. From here details such as the forward LRU rack and the Lox Pot (liquid oxygen converter) could be added (the latter from a piece of cut down Plastruct tube. The 'black boxes' protruding through the bulkhead are a mixture of LRUs as well as the rear part of each Navigators CRT radar monitor.

DSCF0364a.jpg

The vestibule area could then be painted (note the extra LRUs above each CRT monitor).

DSCF0369.jpg

Airfix give the instruction to paint the interior of the aircraft in 'Light Aircraft Grey' HU166, however in my experience this doesn't replicate the colour of the real thing very well. I therefore use 'Light Grey' HU64 as the base since it is closer to what I remember. Admittedly it doesn't have the slight blue tinge of the real thing but it is far closer in shade.

DSCF0368.jpg

DSCF0367.jpg

Edited by Ascoteer

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The flight deck bulkhead could now be detailed.

DSCF0370.jpg

DSCF0371.jpg

The flight deck side of the bulkhead was detailed as per the previous Dominie build because it didn't alter between pre- and post-DAU aircraft. This shot explains what's what on the vestibule side of the bulkhead – yet to be added is the fold down supernumerary seat on the port side of the flight deck access portal.

DSCF0371b.jpg

Edited by Ascoteer

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I'm wondering if this is the first recorded Dominie build that reproduced the supernummary intercom panel and/or the spare fuse box :) (to pick two at random from many)

See Bill was right - you fit right in here :)

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I`ve certainly learned something following this thread and I`m looking forward to seeing them finished,...keep up the good work,

Cheers

Tony

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I wasn't sure how much extra of the flight deck would be viewable via the entry door but decided to superdetail it anyway. The first thing to note was that fitting the vestibule showed up the fact that the flight deck floor as supplied in the kit (part no. 3) sits way too high, the real thing being level with the vestibule floor with no 'step' between the 2. I therefore retained this part (along with the front bulkhead, part no. 8) for a future build of an HS125 CC1A and scratched up a new floor and bulkhead out of 20thou Plastikard using the kit parts as templates. Detailing was done as per the first Dominie build but with the addition of the LP Cocks, Fuel X-Feed/Transfer Lever, and Pressurisation Override Lever to the aft face of the central pedestal, as well as an alteration in the instrument panel layout as per the changes to the real aircraft.

DSCF0372.jpg

DSCF0373.jpg

DSCF0374.jpg

Now a trial fit of the vestibule into the port fuselage half.

Here you can see the detail on the front face of the flight deck bulkhead as well as the fold down supernumerary seat made from Microstrip (yet to be painted).

DSCF0375.jpg

DSCF0376.jpg

DSCF0377.jpg

The flight deck and vestibule sub-assemblies could now be test fitted.

DSCF0380.jpg

DSCF0381.jpg

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I tend not to take much notice of the non aggressive types on here but these are just too beautiful to ignore.

What's next?

John

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Prior to closing up the fuselage I cleaned up the kit entry door (part no.16) and cemented it into the starboard fuselage held in the open position (where it rather neatly hides the fuselage join locating pin). For the soundproofing on the door's inner face I used kitchen foil scribed in a diamond pattern using the back of a scalpel blade.

DSCF0379.jpg

This was then painted, given a wash of dark grey to accentuate the 'creases' and then dry brushed to highlight.

DSCF0383.jpg

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I'm wondering if this is the first recorded Dominie build that reproduced the supernummary intercom panel and/or the spare fuse box :) (to pick two at random from many)

See Bill was right - you fit right in here :)

Well, you know, I aim to please ;)

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Work then proceded much as per the first Dominie build with the maingear wheel bays being altered in position as before, the difference being that, since this aircraft has its flaps in the UP position, the are aft of the wheelbays could be made good with a strip of some 40thou Plastikard and some filler.

DSCF0396.jpg

DSCF0397.jpg

You can see in the last shot how badly the wings fitted on this one - lots of work to get a good joint, then rescribing again afterwards. :sigh:

Edited by Ascoteer

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On to the new nose.

As I've discussed earlier, the nose on the post-DAU aircraft was altered to allow the fitment of the Thomson Sea Searcher radar. This entailed the new nose being 9" longer than before, as well as a change in profile when viewed from ahead (Frame 1 being wider at the top than before, but un-altered at the bottom).

Using the front of the fuselage as a template, 3 ovals of 40thou Plastikard were cut out and laminated together, These ovals were cut oversize and then stuck to the front of the fuselage. The excess plastic was then carefully sanded back until it was just proud of the fuselage. The original radome retained from earlier was then cemented back into place. Note, care should be taken to ensure it is both square as well as aligned with the bottom of the fuselage (since Frame 1 was only widened at its upper edge).

DSCF0384.jpg

DSCF0385.jpg

DSCF0386.jpg

DSCF0387.jpg

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Tsk tsk Debs, not the tidiest join I ever saw

he he

runs like buggery for cover

:)

I can see there's a fair bit of tidying up to do there, that new radar has quite a different footprint doesn't it...

How different is it to the one I remember on the Matchbox kit? Would it have done with a transplant

Edit just looked up a few old BM articles, pointier nose and flashier fuselage

Lovely aircraft

Edited by perdu

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The nose contour can then be built up using thin layers of filler which was then sanded back prior to the next application.

DSCF0388.jpg

DSCF0389.jpg

getting there slowly:

DSCF0390.jpg

DSCF0391.jpg

The radome also needs to be 'blunted off' slightly, giving this:

DSCF0392.jpg

DSCF0394.jpg

A comparison, pre-DAU on the left, post-DAU on the right:

DSCF0395.jpg

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How different is it to the one I remember on the Matchbox kit? Would it have done with a transplant

Edit just looked up a few old BM articles, pointier nose and flashier fuselage

Lovely aircraft

The Matchbox is an HS125-600 the nose profile of which isn't that different to a pre DAU Dom; it's a tad more pointed but is also 6" longer. Unfortunately it is nothing like the DAU nose which (AFAIK) was unique in the HS125 world (I'm not aware of any other 125s being fitted with Sea Searcher).

Edited by Ascoteer

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And that's how I got to where I was when the thread started. Anything from now on is real time. :)

So, a quick reminder.

Pre DAU:

DSCF0440.jpg

Post DAU:

DSCF0445.jpg

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So let's have a look at the undercarriage.

The first thing to say is that the Airfix parts are somewhat crude with overscale torque links. However, more worryingly, the angle(s) of the torque links would indicate that the undercarriage is in the extended (ie unladen) state. This, if not corrected, will seriously affect the 'sit' of the model. HS125s are known for sitting quite low to the ground with a somewhat 'squat' stance (I used to have to get on my knees under the trailing edge of the wing to remove the undercarriage groundlocks on my pre-flight walkround).

Nose leg:

NoseLeg.jpg

Main leg:

MainLeg.jpg

The wheels, however, aside from their lack of tread (and the fact that 125 nosewheels have 'chined' tyres) are a rather good representation of those fitted to the real thing. Certainly the wheel hubs are exquisitely moulded with very fine detail.

Thus, initially the three legs were shortened by 2mm. On the main gear the torque links were removed and new ones made up from stretched sprue. I also added the gear retraction jack, again from stretched sprue.

DSCF0423.jpg

On the nose-wheel leg the bottom part of the torque link was removed and shortened, the top part shortened and then the bottom part re-cemented into place giving a smaller overall torque link at a more correct angle for an aircraft on the ground. Additionally I made up the very noticeable nose-wheel steering jack and arm from stretched sprue and Microstrip.

DSCF0422.jpg

Giving me this:

DSCF0421.jpg

The HS125 has 3 very noticeable hydraulic lines abaft the main gear leg feeding the braking system. These were made up from thin strands of copper wire. Initially I did think about representing the Maxarets (anti-lock brakes) but concluded that they would not be seen owing to the bogie nature of the main gear:

DSCF0424.jpg

Edited by Ascoteer

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Of course then I started to over think the main gear! Having watched Fritag's superb work on his Chippie and JPs I became more and more disatisfied with my representation of the Dom's Main Gear.

Accordingly I decided to strip away the torque links and retraction jacks and start again, Additionally I decided I would model the Maxarets on each leg (these are made from 3 short lengths of stretched sprue on the rear of the leg either side of the brake lines). I then remade the torque links from shaped microstrip:

DSCF0855.jpg

DSCF0857.jpg

DSCF0863.jpg

So,,,,,,,,Thanks for that Steve, you've forced me to up my game. However I think I've gone 'boss eyed' with the effort!

Edited by Ascoteer

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I'm not sure whether "I told you so" starts with I

I think it starts with U Debs

Good catch

Nice work on the brake units

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I tend not to take much notice of the non aggressive types on here but these are just too beautiful to ignore.

What's next?

John

Thank You.

Well it's going to take some time to finish the Doms - I don't want to spoil them by rushing. Having said that I might start something alongside. I'm torn between doing a Jetstream TMK1 or a Hercules C1. Hmmmm decisions, decisions...

Edited by Ascoteer

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This Herc C1

Might she be 202?

;)

Did you know if you sit starboard side just by the rear door the noisy flipping stuff in the roof, just behind the spar groaned when it rattled

In 202, in '74

Now safely nailed to the deck not far from me

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202 became a C3 (ie she got stretched).

I flew her a few times during the Bosnian mess.

As you say, she's now at Cosford.

And her props are still not aligned correctly. Stupid RAF Museum muppets!

The C1 I am going to do will be 292 in the '25 Years in RAF Service' livery (cos I co'd her to a number of airshows and flybys). And I'm going to do her ramp open with a detailed freight bay (gulp).

I may well do a Jetstream first though.

Or I may set them all rolling at once. Who knows? I'm just so unconventional it's amazing!

Another option is a 272 Sqn Beaufighter MkVI (since I am now O i/c 272 Sqn ATC).

Ho hum...

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