A Brace of Dominies

[Ascoteer]

Done

 

[perdu]

I love these Dominies Debs, they are lovely

I don't suppose there will ever be aircraft company designs that look so 'company' again

de Havilland machines always had a style about them in my mind

You will be sure to tell us how you went about them won't you I had both versions of HS125s and just couldn't get my head around making the essential changes to bring them up to the mark

Basically attempting subjects I didn't 'know' well enough

you obviously do

great to have you here, enjoy

b

[ForestFan]

Lovely aeroplane, look forward to watching

FF

[Ascoteer]

Done

 

[Hockeyboy76]

They look good already.

[SHAR67]

Hopefully Airfix will bring this little jem out again one day they both look superb .

Clive

[David Womby]

Those look great.

BTW, can anybody tell me when they first got painted black, pls?

David

[Ascoteer]

Done

[Ptmvarsityfan]

Lovely models of a very attractive

aircraft. I have the Airfix kit in

the stash and look forward to this

build!

Cheers, Paul

[HOUSTON]

I have never seen these aircrafts before but they do look AWESOME.

BEST WISHES AND HAPPY MODELING.

[Hamden]

This pair look superb I look forward to seeing these progress as well as their history

Welcome to the forum enjoy your stay

Roger

[Tomoshenko]

Very nice. I built the Airfix kit way way back as a young lad. Not to these exacting standards mind. Bout time for a re-release. They can throw in a 1/72 VC10 while they're at it too. Look forward to the build threads.

[Alpha Delta 210]

They're a great-looking pair. I look forward to seeing more pictures!

[perdu]

Time for the exposition Debs

Any time you like, nudges...

b

[Ascoteer]

Done

[perdu]

I wonder how many of our friends here were dragged cross country by you at some time or other

b

[fatalbert]

Lovely models,I remember them being converted in 2 hanger at cambridge ,I wasn't on them as I was on herks at the time.Always liked the 125,when I was an apprentice at hatfield they let us play with G-ARYB,the second prototype.Blimy I just worked out that was 30 years ago,feeling old now :-(

Edited January 1, 2015 by fatalbert

[Ascoteer]

On 01/01/2015 at 22:22, perdu said:

I wonder how many of our friends here were dragged cross country by you at some time or other

b

 

[Ascoteer]

[Ascoteer]

On to the first build then.

This will be a Dominie representing a pre-DAU aircraft (Dominie Avionics Upgrade) of 6FTS RAF Finningley. The aircraft modeled will be XS726 'T' which I did my First Solo on New Type on. My intention was to model the aircraft with the flaps down. For those interested in the HS125 series of aircraft, all of what follows is applicable to Series 3A and 3B aircraft and earlier (but not to Series 3A/RA or Series 3B/RA or later), ie to all aircraft lacking the aft ventral fuel tank. Some of what follows will be applicable to later aircraft aside from the flap servodyne mechanism (since later aircraft did away with the servodyne and replaced it with a rotary flap motor).

Before going further, it is probably worth discussing the HS125 services and how they are used, since this may be of benefit to those wishing to model the 125 in a static ground-borne pose.

Firstly, you will never see deflection of the 125 control surfaces on the ground unless it is 'crewed in' or is being serviced in the hangar. This is because it is SOP to fit the control locks on the ground. These consist of a 'claw' that rotates out from the port (1st Pilot's) coaming and engages with the left hand half of the control column 'bicycle handlebar', thus locking both the ailerons and the elevators. Additionally a rudder gust-lock is provided that fits through a flap in the floor of the First Pilot's station and engages in the rudder mechanism (essentially it is a tubular rod that also doubles up as the manual hydraulic pump lever for use in dropping the gear and flaps in cases of hydraulic failure - it was also pretty good for twatting recalcitrant students around the head [i jest]). Turning to the flaps and airbrakes, you are unlikely to see these deployed on the ground (apart from the pre-Taxy checks, or upon the landing roll-out) except in a very specific situation (qv later). Flaps and airbrakes would not be deployed together in the air owing to the fact that the resultant buffet would lead to accelerated flap fatigue with a resultant increased possibility of failure. The flaps on the 125 are 'gated', that is to say there are notches in the flap lever gate at 15 (Take Off flap), 25 (Approach flap) and 50 (Land flap) degrees (from HS125 Series 600 onwards the Land flap gate is at 45 degrees). While it is possible to select proportional intermittent flap settings (based upon the position of the flap lever between the 'gates'), it is not usual to do so. Having said that, on the ground, it is possible for the flaps to droop as hydraulic system pressure decays through the Thermal Relief Valve. Some aircraft were notoriously worse than others for this. Flap droop was a major bugbear when doing the pre-flight walkround checks since it would make it difficult to get beneath the trailing edge of the wing to remove the main undercarriage ground-lock pins and would necessitate opening up the rear equipment bay door (part number 19 in the Airfix kit) to use the Ground Servicing Hand Pump so as to pump the flaps back up to their in-flight position.

The one occasion where you would see an aircraft on the ground with both flaps and airbrakes deployed would be when it was parked outside in strong, or gusting, winds (40kts +). A peculiarity of the 125 was that, after Land flap was selected and after airbrake was selected (usually on the landing roll-out), lifting the airbrake lever through a gate and pulling it further aft would cause the flaps to rotate further to the LIFT DUMP configuration of 73 degrees, which significantly shortened the landing roll. This is the configuration that would be used on an aircraft parked in high winds.

So, onto the build. Initially the lower wing surfaces were cut from the lower (fuselage) centre section, and the centre section retained, thus.

Additionally, the pitot head on the port wing needs to be removed since no production 125 ever had this. I'm not sure what Airfix were thinking of here save that they might have been confused because the 2nd prototype (G-AYRB) did have this during early flight trials. As noted earlier, Airfix got the main oleo locations far too far aft, so the undercarriage oleo bays have to be remade. Also as noted before, the lower wing flap hinge line is wrong and should be filled, before the flap is removed at the correct hinge line:

The black arrowsabove denote the kit hinge line, the red line denotes the actual hinge line where the cut should be made. Looking at the upper wing:

Areas A and A1 are the flap hinge line shrouds, B is the upper airbrake. The green line denotes where the upper surface trailing edge of the wing is when the flap is lowered. For depicting a model with the flaps lowered, this is where the cut should be made.

Cutting the upper wing gives this:

You can see that the airbrake has also been cut out.

Cutting the lower wing gives this:

A comparison:

The lower airbrake was then cut out and the airbrake area boxed in and squared off:

The flap sections that had been removed were then cemented together and the missing area made good with an insert of 30thou Plastikard sanded to an aerofoil shape:

The HS125 had double-slotted flaps and these would need to be replicated for an aircraft in the flaps down configuration. Initially I made up a 'ladder' from Microstrip. The main member was 20thou x 40thou, with the 'rungs' being 10thou x 20thou. After they had set the 'rungs' were shortened, and the 'ladder' cemented to the flap. This secondary flap slot should lie just forward of where the 30thou Plastikard filler was let into the kit flap (the grey part being the after end of the upper flap surface):

Edited August 12, 2015 by Ascoteer

[Fritag]

I have just over 1000 hrs on the Dom - wazzing around at low level with the baby Navs and pretending to be a Tornado (albeit at 1/2 Tornado speed) was some of the most fun I've ever had with my clothes on!

Ok - not sure I can have got this right - so you may have to correct me.....you were sat up the front (having a whale of a time and who wouldn't want to chuck a dominie around at low level ) and the baby navs were sat down the back trying to navigate at low level using only a weather radar????? Oh my. I am sooo glad I didn't end up as a nav.

Fascinating stuff Debs.

Excellent modelling.

Great thread.

[Foghorn Leghorn]

Whoah, that's what I call major heart surgery on a kit's wings. Impressive work.

[Ascoteer]

Ok - not sure I can have got this right - so you may have to correct me.....you were sat up the front (having a whale of a time and who wouldn't want to chuck a dominie around at low level ) and the baby navs were sat down the back trying to navigate at low level using only a weather radar????? Oh my. I am sooo glad I didn't end up as a nav.

Oh it gets worse!

While I was up the front hooning (that's a technical Domnie term - it's a bit like 'wazzing around' but a wee bit more hooliganish), and with a window to look out of, the baby navs were sat down the back facing rearwards and navigating using only a weather radar and they didn't have a window neither!

We saw pity on them with the post DAU aircraft - the radar performance was similar(ish) to that of Tornado and at least they got to sit facing forwards.

It didn't shut them up though.

[Shaun]

Nice pair,looking good.

I quite like the Domine as they were the most common military type in my area after the closure of RAF Brawdy! They were regularly seen on low level nav exercises. PD to overshoot were occasionally seen in the Withybush circuit, giving the Cessna's pilots something a bit quicker to avoid and worry about.

Shaun.

[Ascoteer]

Whilst waiting for the wing modifications to set I turned towards doing the flight deck. Given that my post DAU Dominie will have an open crew entry door which should make things more visible, I figured that I would have a go at super detailing (for practice) the working end of the pre DAU model. Specifically by adding the services controls to the central pedestal and instrument panel.

Dominie flight deck bulkhead with fuse panels behind the Pilot's Assistants seat, fuse panel lights, and portable fire extinguisher behind the First Pilot's seat:

It's worth noting that the Airfix seats are actually quite reasonable reproductions of the real thing, however the Flight Deck as it stands is too long, the seats set too far back and the instrument panel too far forward – the real thing could be said to be quite cosy!

Additionally the control columns are slanted (which is not the case with the real thing) and the centre console is far too tall. I therefore shortened the Flight Deck floor such that the front bulkhead/instrument panel would sit just aft of the locating slot, moved the seats forward, scratched up the instrument panel, shortened the centre console, moved the control columns back and set them to the correct perpendicular angle. Seat harnesses were also provided.

The Dominie 'office':