Another 1:24 Harrier GR.3

[xffw45343tg]

Hi all.

Having been snooping around on this forum for far too long I thought it about time to introduce the world's slowest GR.3 build. I originally started this a LONG time ago with my son as an "out of the box" project but I was a bit ambitious in the choice of kit and scale and not surprisingly he got bored. At about this time, I was persuaded that I really ought to fix the auxiliary intake doors - at which point the project ground to a near halt. Inspired by Jake Eaton's fabulous FA2, Jen's great GR1 etc and helped by the fabulous people at the Harrier SIG, I keep picking this up from time to time and doing a bit more. Needless to say the "out of the box" approach went out of the window...

The intakes that started it all.

Frames under the engine

MLG Bay frames and fuel tank

Various stuff

All of which takes us up to date. I've been working on sorting out the airbrake bay. The Airfix bay is much too large and shallow (so I cut it out, having not thought to sort the problem before joining the fuse halves). On a GR.3. the airbrake overhangs the aft and sides of the bay, the aft end of which should be level with the large avionics bay access panels above it. The operating jack sits between a couple of longitudinal members. Behind the bay is an access panel to the fuse panels, into which are sunk the chaff/flare dispensers on later a/c. The panel lines in this area are very wrong and should meet the aft end of the panel.

Anyway, enjoy and feel free to throw stones. And yes it does need more filling and smoothing doesn't it?

Cheers,

Kirk

[Seamus]

Looking very good Kirk.

My only criticism would be that its going to put my build to shame

Seriously though, some excellent scratchbuilding, something that's unfortunately beyond me. I see what you mean regarding the airbrake; I'll have to have a think about whether I'll make those alterations, at the risk of ruining my build completely!

Look forward to seeing her progress

Shaun

[xffw45343tg]

Thanks for your kind words Shaun.

Before you start putting your build down, I would point out that you haven't seen my sparse OOB cockpit which is nothing like as good as yours!! And yours looks far more likely to get finished.

As regards the scratchbuilding, I'll share a top tip. All those business cards people give you make an excellent templates for the various frames and panels you need. I normally cut one very roughly to the shape I need then put it in place, noting where it is over or undersize with pencil arrows. If you moisten the edge slightly where it is oversize, it will squash down a bit if needed. The next card is normally nearly correct and by the time you've done three, it transfers onto plastic card quite well. The big mistake I made was to not start detailing until after I'd glued the fuselage together.

The most difficult part is probably getting good enough references to work from; here's a few cameraphone shots I took at Hendon:

Like I said before, let me know if there are any pics you need for yours and I'll see what I have - especially if you plan on doing anything with the engine as the Airfix one is more wrong than an accountant at a rave.

Cheers,

Kirk

[Tim B]

I can see this one taking a while Should give you enough time to work out where to put the thing when you're finished. Looks great so far!

[Seamus]

Cheers Kirk.

Was actually at Hendon myself last Thursday and got a few pictures for reference; mainly of the undercarriage and the engine. Plus I've received plenty of other material from other sources, so reckon I'm pretty well set.

Let me know if you'd be interest in the pics and I'll stick them up on the forum for you

[JakeEaton]

It's looking brilliant!

Can't believe there hasn't been more comments on this thread. Some good looking scratchbuilding here. You've made a good start on the MLG bay, an area I'm really not looking forward to. However I think the doors and practically closed when static so totally detailing it probably isn't necessary. The same can be said for the front landing gear. Have you made a start on the cockpit yet?

Looking forward to more updates!

[xffw45343tg]

Thanks for your kind words Tim. You're going to need a lot of popcorn.

Little progress to report. Thought I'd post a couple of pics of last night's work:

I've been sorting out the main engine access panels, numbered 11 & 12 P&S on the real thing but just a big lump of plastic in the Airfix. On the original "OOB" attempt, I'd spent a lot of time hollowing out and thinning the 2 vents on the forward panels but then those nice chaps at the Harrier SIG pointed out that they are only found on GR1s and a few early GR3s before they were fitted with the Mk.103 engine. This engine changed from having 2 alternators to a single integrated generator that didn't have the same cooling requirements. However, a vent was added for the auxiliary power unit generator, which is a small cylindrical unit on top of the starter, just ahead of the intake duct.

I cut the old vents off and filled them with plastic card, filler and a bit of cyano glue. The new vent was carved from a bit of sprue that I'd drilled a hole in (it's very soft so is quite easy to work) and then I traced around it on thin card for the flange. You may notice that the GTS/APU intakes and exhausts have been opened out; the intake will have a small piece of mesh but the exhaust hole just opens on to the duct underneath.

I'm vainly hoping to keep the access panels removable so I've got quite a job to do to get the parts to sit flush with the wing. I had to add a bit of plastic card to the aft starboard corner and filler to blend it in.

Not much else to report. The carpert monsters (or children?) have eaten the small panel at the base of the airbrake so making a new one from card is probably the next job. After of course more filling, sanding, painting, sanding, painting, sanding, sanding, sanding...

Cheers for looking,

Kirk

[xffw45343tg]

It's looking brilliant!

Can't believe there hasn't been more comments on this thread. Some good looking scratchbuilding here. You've made a good start on the MLG bay, an area I'm really not looking forward to. However I think the doors and practically closed when static so totally detailing it probably isn't necessary. The same can be said for the front landing gear.

Cheers Jake - It was your FA2 that got me detailing this!

MLG is a tricky decision; you are perfectly right that the doors are usually shut but they can be opened for servicing, access to the water pump, etc, and the stuff in there is pretty well covered in reference material so i've kinda opted to detail the bay and leave the doors open. The big mistake was the decision to do this AFTER joining the fuse halves. Basically the forward bulkhead is all wrong:

- the 'moulded' water tank in the engine bay is too small

- the ribbing on the bulkhead is too thick

- the box around the MLG pivot is too tall

I can go on but will probably bore most readers so PM me if you want any pointers.

Have you made a start on the cockpit yet?

Hmm. The cockpit went together when I was still in OOB mode so its a bit more basic than I'd like. I may go back and squeeze in the missing frames and panels but it will never approach yours so I might have to cop out...

Looking forward to more updates!

Don't forget I'm the world's slowest modeller and progress is glacial. But thanks for the sentiment!

Kirk

[JakeEaton]

Just seen your update regarding the APU intakes etc. Looks very good so far!

As for the pointers, I don't see any reason why you shouldn't post it all up here. It would be easier for other builders of harriers to see your knowledge of areas like the MLG bay etc. It doesn't bore anyone

[xffw45343tg]

OK, some main landing gear bay stuff. Stay awake:

The bay of the real thing is formed between frames 29 and 33, which are represented by Airfix parts 105 and 107 respectively. If you are planning on having the engine bay visible, I'd recommend throwing away 105 after using it as a (rough) template on a bit of card. I say rough because it doesn't fit the fuselage without big gaps. Ho hum.

Ahead of frame 29 is the box in which the pivot for the strut is located. The top of the strut houses a latching mechanism that is pretty similar to your average Yale lock. The strut is raised and lowered by a jack that lies slightly to port of the strut and sits within a box that extends under the hot bifurcated section of the engine. This is kind of modelled in part 105, although the actual box is much shallower (I took off about 5mm) and the pivot for the strut is much lower down, closer to the skin of the aircraft. I think the reason Airfix raised the pivot point is that in the real thing, the strut is lengthened on retraction, pushing the wheels further into the top corner of the bay; with a solid strut, the geometry simply wouldn't work. This means the Airfix strut (and sadly the Heritage one too) is actually the wrong shape... I've opted to leave well alone on this model and save scratchbuilding the necessary bits for the next project.

Back to the bay.

At the top of the bay is a cover for the central fuel tank, which extends to the upper skin and is integral with frames 30, 31 and 32. It has a curved lower surface that extends about 5mm below the Airfix part 106. The frames can be located by the rivet craters Airfix kindly provided on the fuselage. Having not thought to make the frames before closing up the fuselage, I had to make them as separate fillets which you can see in the 4th and 5th pictures of my first post. The frames have holes in them of varying sizes to allow various bits of ducts, pipework and cables to pass through. On the starboard side, the lowest hole is for the rear reaction control duct. Above that is one for cooling pipes (of which more in a mo) and the top one is mostle cables. There is a plate between frames 31 and 32 on which is mounted an as yet unidentified electricals box (fuses?). On the port side the holes are of different sizes and in different positons (it the frame is not symetrical). The lower hole contains the control cables for the elevator and rudder, the middle one hydraulic lines and the top more cabling. In the aft 2 spaces between the frames are found the 2 nitrogen tanks used for blowing down the gear in an emergency. There is a hydraulic accumulator on the aft face of frame 30.

The fuel tank lower cover has 2 depressions for the tyres when retracted.

The complex components on the aft face of frame 29 above the strut are part of the water pumping system. Water enters from the tank through a opening in the bulkhead offset slightly to starboard. The pipe bends outboard and runs to the cylindrical pump body. The pump is powered by bleed air that travels down the larger of the 2 pipes that have been omitted from the top of the engine (the smaller is the water delivery pipe), through a couple of gimbal pipes and emerges in the lower right of the MLG bay, level with the water inlet. The pipe branches at the water pump and continues on through the MLG bay to cool the avionics bay aft of it. There is a filter in this pipe between 32 and 33. Exhaust from the water pump exits straight down, immediately outboard the strut housing. Outboard of this is the water jettison pipe. Both these 2 are flattened at the end where they pass through the skin.

On the starboard side of the strut is a link to the bay door retraction mechanism. This has an extending lever on it that allows the doors to be opened manually for servicing etc.

As I mentioned before, the water tank sits on the engine bay side of frame 29 on a pair of brackets to which steel bands are attached to secure it in place. The tank is much larger than the dodgy bit of moulding on part 105 would have you think and obviously there is no recess on the MLG bay side where the water pump components are mounted. Think I'll carve my tank in balsa or similar. Shout if you want one and I'll see if Ian at Heritage is interested in using mine as a master.

The bay doors pivot from frames 30 and 32. I'm not yet sure how to scratch build these as they probably need to be a bit stronger than they will be if I make them out of plastic. Brass is probably the stuff required and I'm expecting them to be a bit fiddly.

The smart money does exactly what Jake suggests and models the doors shut - though note that they tend not to be flush if the gear is down.

If you've managed not to nod off, here's a few more pics.

The completed APU generator duct. The filled outlets refuse to lie down flat and I've since put another layer of filler on.

A couple of shots of the cockpit. As I keep bleating in excuse, this was originally going to be OOB but I don't think it is up to the standard of you Britmodeller types so I'll have to re-visit it to add some frame detail etc.

Incidentally, I plan on going back to white primer before the colour coat. Grey is just a bit easier to see all the imperfections.

Thanks for looking,

Kirk

[Mike]

I've just been playing catch up on this one, and I'm liking it a lot. Keep up the good work Kirk (sorry for the rhyme) and take lots of pics

[Seamus]

Blimey Kirk thats a lot to take in! I'm blatantly going to be a coward and fix the gear doors shut, no way on Gods green Earth I'll be able to pull off these bays to that level of accuracy

All is looking good though, coming along very nicely indeed

Edited June 16, 2008 by Seamus

[JakeEaton]

Excellent stuff Kirk, your paragraphs on the details of the MLG bay is PRECISELY what I want to read. Your knowledge far surpasses mine on the intricacies of the aircrafts systems etc so it's very good reference for when I get to that stage in my harrier build.

As for the gear doors, especially the front landing gear, I'm only going to superdetail the 'rear' part of the bay (where the front gear connects and all the hydraulics are) with the other sections being roughly detailed but not extensively. As the doors are raised (but not flush) you'll still be able to peek in but not enough to see it all, so why bother? There are simply just to many pipes and small bits and bobs to build without losing your mind.

How are you going about filling the rivets on your build? Nick Greenall seems to swear by multiple coats of automotive primer, something I'm interested in trying.

[Craig S]

That's looking excellent! don't worry about the timescale, there's no rush!

[xffw45343tg]

Thanks chaps.

Still the old intake points refuse to come smooth. More filler (Humbrol stuff - it shrinks) and wet & dry applied. Photo's would be pointless. I've started penciling lines where I now need to retrospectively detail the cockpit. Anyone know a keyhole surgeon?

Jake (and anyone else!!),

Here's a link to some good MLG bay reference on an AV-8A, and here's one to the Hendon GR3 airbrake bay with the panel behind it.

With regard to the rivet craters issue, I'm going along Nick Greenall's "lots of auto primer" route, although I have put filler in a few areas where they are particularly deep or need totally eradicating (e.g. the main avionics bay APs). I think it depends a bit on the distance from which you expect your model to be viewed; that probably sounds a bit obvious but what I mean is the rivets on a real GR3 are discernable from a distance, although they are mostly flush and the surface is pretty smooth. A few thick coats of paint on your Airfix and average light levels and the effect from half a metre will be pretty adequate. However, if you are doing Jake-level-"Oh-my-god-that's-not-a-model-is-it?"-superdetail then I think that they're just too deep and will need filling and replacing with hand made scale replacements (secured both sides), both flush and domed that will bear inspection with a microscope . Don't forget that if you are going to fix all the panel line "bugs" (sorry - I'm in IT) then that will inevitably mean obliterating many of the existing rivet markings, so you may not be able to get a consistent finish this way. If Desmojen sees this, perhaps she'd like to comment - her GR.1 was very impressive (and completed in the time it takes me to find the filler).

Nose Landing Gear Bay. Be aware that the doors are normally found OPEN with the aircraft on the ground (something to do with inspecting hydraulic systems - Alfie at the SIG would know) so they need some attention. The Kagero book has very good references and I have some copyright stuff that I can't post but could let you see. I wasn't that impressed with the Airfix FRS parts btw - look like they were modelled by someone who knew someone who'd once looked in the bay on a dark night when drunk (sorry Mr Airfix).

Shaun,

You sell yourself short. I think your Harrier looks great. Buy a sheet of plastic card though - filling in the huge cavernous gaps infront of the nozzles will make your plane a million times better than the base kit and is much easier to do than even sticking the halves together. I'll try and dig out some references for you.

Craig, Mike,

I appreciate the encouragement. I've sped up no end since starting this post!!

Cheers,

Kirk

[Azgaron]

Very nice work so far, Kirk! Love to see more!

Cheers,

Azgaron

[xffw45343tg]

Hi all. A little update.

I'm working (slowly) on lots or areas at once:

1) Having looked at Hasegawa's intake construction, I decided to separate the intake bell mouths. So from the 1st pic of this thread it became:

and now this:

In between, I managed to put one side in my work bag and crush it, so ruining all the filing and polishing. The last coat of primer revealed pin-holes, so I've not finished this one yet...

2) I've mad e abit more progress on the airbrake. Here are some more bits of card to detail the "floor" (at the top of the bay, if that makes any sense) and the longitudinal members:

I'm finding this component a bit dull, which is probably why I started...

3) ...tailplane detailing. Something possessed me to make the tailplane pivot and fin mounting more realistic. The forward root of the fin is in fact attached to the fuse and is an intake duct for the avionics bay conditioning system. Behind it is a removable cover for the rudder actuator, with the fin proper being the section behind this. As can bee seen from Airfix's handy rivet detail, the fin is made from a box formed of structural spars, the forward and aft of which are bolted to the fuse. The aft attachment point is on of the frames (I'd have to look up the number so I won't) that passes through an aperture in the single piece stabilator. Airfix don't make it like that. So I did this:

to the "spare" GR1 tail to see whether the parts could be divided. I'm using the forward section for the intake duct and have hollowed it out accordingly. Then I cut out the opening in the tail plane. Using some old business cards I made a template for the aft fin support frame, which I then improved, then made in styrene sheet:

This was then test fitted to the fuse:

I've got to think about how I'm going to join the tailplane pieces and make a pivot that will be strong enough - think some brass tube will be in order.

There's a bit more rivet filling that's been done in a couple of places - not worthy of pics just yet.

That's all for now.

Cheers,

Kirk

[JakeEaton]

Interesting update Kirk. Do you have any idea on how the one piece tailplanes actually pivot?? Also, from pictures I have, (looking at the starboard side) I can see a large blue 'thing'...any clues?

This is one area I'm glad you're doing as I have no idea what's going on in that gap where the tailplanes 'axle' is...

Also, what's the reason for the intake redesign?

[Dave T]

The tailplane is attached to the fuselage by a pair of pivets on top of the fuselage & underside of the tailplane (item 1 in the photo below). The tailplane itself is a one piece unit therefore the whole thing moves as one, via a hydraulic jack which is itself connected to the control column (item 2 in the photo below)

AP diagram 1

If it helps, here's a panel access diagram also.......

AP diagram 2

Cheers....

[xffw45343tg]

The tailplane is attached to the fuselage by a pair of pivets on top of the fuselage & underside of the tailplane (item 1 in the photo below). The tailplane itself is a one piece unit therefore the whole thing moves as one, via a hydraulic jack which is itself connected to the control column (item 2 in the photo below)

AP diagram 1

If it helps, here's a panel access diagram also.......

AP diagram 2

Cheers....

A man with APs! Fantastic Dave - what can I say? There is no better source of info for those of us who can't afford our own Harrier

Jake,

The bit of your question that these diagrams doesn't answer concerning the intake duct; if you take a look at your Airfix parts (67 & 136 I think) you'll see that there is a little step about halfway along it. Now imagine what happens when the auxiliary intake doors open and you'll see that they would open on the back of this "duct", with the air never getting to the engine fan. Err.. no. In the real thing, there are 2 separate bell mouth openings. One is the visible forward edge of the intakes, the other sweeps outwards from the fan to the aft edge of the AI door ring so that the doors are sucked open by the airflow to the fan whenever there is insufficient forward speed to keep them closed. When the doors are open you can see the face of the fan through them (as you get sucked in).

So if you take a look at my 1st pic on this thread, you'll see I added a piece of styrene the outer edge of which was shaped to the opening in the fuselage parts (66 & 151) and the inner to the corresponding points on the ducts. I then cut out a slot up to the step and stuck the styrene to the duct using copious amounts of filler and shaped the (aft) bell mouth, which, when fitted in place will look very much like the Hasegawa Harriers' intake. I plan to add the webs between each door to the new bellmouth and then sit the forward intake section on this. Sounds more complex that I expect it to be. Nick's FRS1 is the only 1:24 I've seen done "properly" in this respect.

Blue things? Dunno. Might be the jack for the stabilator? Point me at a picture and I'll try and come up with a better answer.

Cheers,

Kirk

[Mike]

Blimey, this is getting technical! Keep it up though guys, this is the kind of inspirational modelling I love to see

[Dave T]

Now imagine what happens when the auxiliary intake doors open and you'll see that they would open on the back of this "duct", with the air never getting to the engine fan. Err.. no. In the real thing, there are 2 separate bell mouth openings. One is the visible forward edge of the intakes, the other sweeps outwards from the fan to the aft edge of the AI door ring so that the doors are sucked open by the airflow to the fan whenever there is insufficient forward speed to keep them closed. When the doors are open you can see the face of the fan through them (as you get sucked in).

I think i see where Kirk's coming from. The intakes immediate interior edge stops short half way inside, where it meets the blow in doors. This is the area shown in the two shades of grey in the photo below of a SHAR 2 cockpit section.......

Photo 1

The rear part is painted in white.

And here's a photo you won't see often.... it's an intake (starboard) sectionally removed lengthwise from a cockpit (ala an Airfix kit), which shows the blow in doors area (sorry about the quality).

Photo 2

Hope this helps ?

.

[Stuart]

Hey folks. Great work on this machine Kirk!!!

As a long time Harrier fan (no pun intended), I do follow this intake malarky. However, I am puzzled as to why the fan suction speed on the inside of the intake does not overcome the outside speed, thus holding the blow-in doors in.

What I'm basically saying is that I didn't think the external speed would ever exceed the internal speed...because of the fan suction.

Does anyone get my question?

Thanks

Stuart

[Dave T]

Without getting too technical...remember, the blow in doors work when the aircraft is in the hover, therefore there is no air outside to rush in. All the air is drawn in by the fan on the engine. As this isn't enough ( the doors are loose btw ) when a Harrier stops in mid-air, the suction from the fan opens them thus drawing in more air. When parked up, the upper doors 'fall in' due to gravity hence some appear open, while bottom ones appear shut (as correctly rectified by Heritage's resin intake replacements). During forward motion at speed, the air outside is slower than inside the intake due to the fan 'sucking' it in also. Therefore by default, the blow in doors are forced out (i.e. flush) during normal flight

.

Edited July 15, 2008 by Dave T

[JakeEaton]

Yes that makes sense. So you're going to go the same route as Nick and create the intake area up to the blow in doors, glue the blow in door 'walls' to that, then glue the forward part of the intakes onto them.

One question, are the blow in doors thick or just sheet metal?