Author Topic: McDonnell Douglas AV-19A  (Read 21892 times)

Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #25 on: January 30, 2012, 07:53:58 AM »
While looking at the F-35 engine system, it struck me that there were some 'puffers' missing as I could only see two for roll control while in the hover.  Pitch seemed to be controlled by the variable pitch lift fan at the front but I just couldn't figure out how the yaw was controlled.  Knowing Greg (GTX) is involved with the F-35 program, I asked him how it was done, he directed me to a video clip and it showed that once the exhaust nozzle has swiveled down, it could be 'rocked' side-to-side. This was how the yaw is controlled and my project will use a similar system, plus I'll have the bottoms of the cold air ducts rocking too.  So if the exhaust was rocking to the left, the cold air duct would rock to the right (that's looking from the back [or front -whatever]). Also both the exhaust and cold air ducts could rock in the same direction as I think this could help doing vertical landings with a certain amount of crosswind.  For pitch and roll I would have a variable area control in the cold air ducts, with the pitch control, both area controls would move at the same rate, whereas in the roll, one variable area control would open while the other closes.  Of course there would be infinite adjustment for all conditions.
« Last Edit: January 30, 2012, 07:55:56 AM by kitnut617 »

Offline ChrisF

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Re: McDonnell Douglas AV-19A
« Reply #26 on: January 30, 2012, 08:17:40 AM »
Coming along nicely... I wish i was as confident at hacking up stuff :)

Offline elmayerle

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Re: McDonnell Douglas AV-19A
« Reply #27 on: January 30, 2012, 09:10:39 AM »
The uprated Pegasus you're talking about is the Pegasus 15, initially proposed for the AV-16 and partially trialled on one testbed engine before cancellation.  According to The Heart of the Harrier, the existing Pegasus still has some growth in it and a stretched and upgraded AV-8B+ was studied before it was determined to do an "all-new" aircraft with JAST, JSF, etc.  That's one I'm looking to model as a what-fi "fallback" for the F-35B falling afoul of Pentagon bureaucracy.

Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #28 on: January 30, 2012, 09:20:03 AM »
I would like to get a copy of that book Evan, who's the author and what is the IBSN number please.

Offline kitnut617

  • Measures the actual aircraft before modelling it...we have the photographic evidence.
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Re: McDonnell Douglas AV-19A
« Reply #29 on: January 30, 2012, 09:23:24 AM »
Coming along nicely... I wish i was as confident at hacking up stuff :)

Well I don't just start chopping things up Chris, most times I've been thinking about a project for months, sometimes even years and then along the way it all comes together in my mind.  So when I start to chop somethings up, it seems to go quite smoothly

Offline elmayerle

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Re: McDonnell Douglas AV-19A
« Reply #30 on: January 30, 2012, 10:22:40 AM »
I would like to get a copy of that book Evan, who's the author and what is the IBSN number please.
PM inbound to you with the info.  Anyone else care for it, please ask.  ISTR that it was recommended, when first released, over on the Secret Projects board.

Offline kitnut617

  • Measures the actual aircraft before modelling it...we have the photographic evidence.
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Re: McDonnell Douglas AV-19A
« Reply #31 on: January 30, 2012, 10:44:05 AM »
I would like to get a copy of that book Evan, who's the author and what is the IBSN number please.
PM inbound to you with the info.  Anyone else care for it, please ask.  ISTR that it was recommended, when first released, over on the Secret Projects board.
Cheers Evan

Offline finsrin

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Re: McDonnell Douglas AV-19A
« Reply #32 on: January 30, 2012, 03:47:45 PM »
AV-19 is so well thought out before any/much plastic was cut.  Like real areospace R&D and it shows.
Where as (without any particular plan) I open kits looking for parts which look like they will fit or some how work.
Impressive creation.  When done, send pictures and description to Boeing.
Bill   :)

Offline tc2324

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Re: McDonnell Douglas AV-19A
« Reply #33 on: January 30, 2012, 08:12:32 PM »
Great looking concept and very surprised that it`s size is similar to the Harrier.
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Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #34 on: January 30, 2012, 09:58:36 PM »
Thanks everyone ---

Here's a pic comparing it to a 1/72 F-15

Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #35 on: February 02, 2012, 06:42:08 AM »
Now that I've explained my engine concept, I should now explain how I got to where the model is now.  As I have previously said, I was going to use the F-15 air intakes, and because I want to keep a Harrier connection, my plan was to use a Harrier forward fuselage/cockpit area.  I also want to use Harrier fins/rudders.

With that determined I measured across the intakes and fuselage and got about 37mm, I then needed to sort out what the u/c would look like.  First off, as this was to be a much enhanced Harrier, I had to figure out what would be needed for such an aircraft, I've noticed that the carriers that the USMC uses don't utilise the 'ski ramp' that the RN used, which to me must limit what the Harrier could take-off with.  So I determined that for this project it would have to be Catapult Launch capable, and/or vertical landing recovery.  And McD have a very good proven front u/c leg to do that -- from the F-18, so that's what I'm going to use there.  For the main u/c gear though it wasn't so simple at first, I've studied the F-35 and I like the wide wheel track it has and I wanted something like that for this project, but I didn't want the u/c leg attaching to the wings, or have them folding up into the wing root, I wanted them on, and in, the fuselage.

The engine concept though eliminates the bicycle u/c system of the Harrier, which meant a more traditional tricycle style but I couldn't find anything that would fit into what I had in mind.  The F-15 u/c wouldn't fit to where I wanted it to go plus it didn't have a wide enough track, and the F-18 u/c which had a wide track, folded away in the wrong direction plus it wouldn't fit there either.  But while rumaging through the spares box I came across the left over bits from a Panavia Tornado, and measuring across the front end of the forward center of the fuselage found it practically matched the dimension I had for the F-15 intakes and Harrier fuselage.  Perfect I thought ---  plus the u/c as it extends gets wider than the fuselage which gives it quite a wide track.
« Last Edit: February 02, 2012, 07:12:03 AM by kitnut617 »

Offline kitnut617

  • Measures the actual aircraft before modelling it...we have the photographic evidence.
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Re: McDonnell Douglas AV-19A
« Reply #36 on: February 02, 2012, 06:55:22 AM »
Then it was on to how the rear end would be like.  The engine concept more or less dictates that the fins and tailplanes would have to be mounted on twin booms, although the fuselage could have gone above the engine, like an F-4 or F-101.  But that's not what I wanted, so doing some measuring of the F-15 rear end it looked like if I had only one engine tunnel, it would be very close to the rear end of the Tornado center fuselage.  Before I cut any plastic though I did some calculations to what sort of exhaust opening I would need.  As the hot exhaust is supposed to be about 20,000 lbs of thrust I took a cue from the Vulcan engines to size the tailpipe which is about 10mm diameter in 1/72 scale.  I then worked out the area of the pipe then worked out what the F-15 engine tunnel area was and to my surprise, it worked out (after I deducted the tailpipe area) to be a bit more than the tailpipe area.

So I then carefully cut down the top and bottom center of each F-15 engine tunnel, discarded all the parts in the middle and glued together all the outside parts and got this.
« Last Edit: September 11, 2017, 02:17:48 AM by kitnut617 »

Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #37 on: February 02, 2012, 06:58:33 AM »
My plan was to only use the wheel bays of the Tornado, so I cut what I needed off the bottom half, then with a bit of juggling and notching of parts, got the F-15 parts interlocked with the Tornado part

Offline ysi_maniac

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Re: McDonnell Douglas AV-19A
« Reply #38 on: March 10, 2012, 12:49:57 AM »
Most interesting!

Offline Rafael

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Re: McDonnell Douglas AV-19A
« Reply #39 on: March 10, 2012, 08:41:18 AM »
100% Pure, unadulterated awesomeness!!!  8)
I don't take life seriously. I'm not getting out of it alive anyways.

Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #40 on: March 11, 2012, 08:03:21 AM »
After I got the two parts glued together I then had to blend in the sides, I did this by carefully cutting down each side of the engine tunnel, then along each side.  Then I 'massaged' the plastic to fit to the rear of the wheel bays and then added some styrene card and some putty.

Offline kitnut617

  • Measures the actual aircraft before modelling it...we have the photographic evidence.
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Re: McDonnell Douglas AV-19A
« Reply #41 on: March 11, 2012, 08:12:07 AM »
I then switched to the front end so I could determine where the cockpit etc would go.  As I said previously, I thought that I could reduce the intake area slightly because of the less power the engine would need, but I also had to keep in mind how the bodywork would flow over the new intake ducting that leads to the fan front. 

What I did was reduce the intake height by about 1.5mm by cutting off the bottoms of the intakes.  I then re-glued the bottom half on by lining up the leading edges, this made a bit of a offset at the rear end of the intake so I cut it so it was all in line.  I also cut along the inside edge of the top side of the duct and gave the topside a bit of a twist, this will blend into the new body shape further downstream. You'll notice I've also cut off the leading part of the wing root as this will be attached further down the fuselage

Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #42 on: March 11, 2012, 08:17:20 AM »
From here I could now determine the shape of the new intake ducting which would be a rectangle-to-round.  I made myself a rectangle-to-round from thin styrene card after developing it using my drawing program (AutoCad)

Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #43 on: March 11, 2012, 08:24:35 AM »
The new duct is actually an 'offset rectangle-to-round' because I'm keeping the bottom of it level.  The fan front is 19mm diameter, the rectangle is 15mm high by 35mm wide and the two faces were 20mm apart.  I say were because as I got into the build I found I had to lengthen it and while doing that I refined the dimensions of the round and rectangle ends. It ended up 5mm longer between faces.

Here's a comparison of the new duct and a AV-8B (GR.5) duct and the two ducts I made.  I also changed which side I was going to join the two halves because I forgot to allow that the duct would lie flat on the bottom of the rear fuselage.  You can see also how the two intakes interact with the duct.

Offline kitnut617

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Re: McDonnell Douglas AV-19A
« Reply #44 on: March 11, 2012, 08:28:50 AM »
Here you can see basically how I was going to lay it all together and at this stage it looked like it wouldn't be a lot bigger than a Harrier, slightly longer by the time I get the forward fuselage in.
« Last Edit: March 11, 2012, 08:31:30 AM by kitnut617 »

Offline kitnut617

  • Measures the actual aircraft before modelling it...we have the photographic evidence.
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Re: McDonnell Douglas AV-19A
« Reply #45 on: March 11, 2012, 09:00:58 AM »
Up to this point I intended just to use parts from F-15's and Harrier kits, the wings and tailplane are from a 1/100 scale F-15 kit, while all the F-15 fuselage parts I'm using are from a 1/72 kit.  The Harrier and Tornado parts are 1/72.  This all changed because I just couldn't figure out how I was going to join the Harrier forward fuselage in between the two intakes, the Harrier fuselage just isn't long enough.  What got me looking at the F-18 was after I had looked at Eddie M's wonderful F-15/F-18 kitbash on the other forum, and after I had already decided I was going to use the F-18 front leg because I wanted the AV-19 to be catapult launch capable it just seemed to me I could use the u/c bay from the F-18 too.  I got hold of a cheap Hobbyboss F-18 which turned out to have surprisingly very good detail. 

Matching up some parts from the F-18 and Harrier I found the fuselages were almost the same width and I thought at first I would line up the upper Harrier and lower F-18 parts right where the nose cone would join on both.  Problem was where at a point the two fuselages were the same width, the F-18 got narrower towards the nose cone and the Harrier got narrower towards the rear end of the cockpit.  I had planned on using the Harrier nose cone but then I had a change of mind, I decided to use the F-18 nose cone and here's why.

Offline ysi_maniac

  • I will die understanding not this world
Re: McDonnell Douglas AV-19A
« Reply #46 on: June 02, 2012, 02:15:20 AM »
Top Notck whiffery! :)

Offline Tophe

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Re: McDonnell Douglas AV-19A
« Reply #47 on: June 02, 2012, 01:18:13 PM »
Looking good!

Offline kitnut617

  • Measures the actual aircraft before modelling it...we have the photographic evidence.
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Re: McDonnell Douglas AV-19A
« Reply #48 on: June 02, 2012, 10:14:53 PM »
Thanks guys, this project has taken the back seat at the moment because of my Sunderland one. 

Anyway I can update  this a bit.  As I was explaining about the forward fuselage, connecting the Harrier cockpit had posed a problem but then it all started to fall in place once I decided to use elements of an F-18 forward fuselage.  I had got hold of a Hobbyboss kit of the F-18 and even though the kit is very nice, it's part breakdown is very simple, basically there's the top and the bottom.  The top pic is how the parts come as, the bottom pic is where I've cut the forward fuselage bits off as this is all I'll use as well as the nose cone and front u/c and wheels from the kit.

Offline Litvyak

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Re: McDonnell Douglas AV-19A
« Reply #49 on: June 02, 2012, 10:26:04 PM »
This is brilliant stuff! Concept to execution, I love it. :)
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