Beyond The Sprues

Current and Finished Projects => Physical Models => Aero-space => Topic started by: kitnut617 on January 07, 2012, 03:52:59 AM

Title: McDonnell Douglas AV-19A
Post by: kitnut617 on January 07, 2012, 03:52:59 AM
I've got this going on at the moment, a Harrier Replacement  (not an alternative to the F-35 I might add)

Title: Re: McDonnell Douglas AV-19A
Post by: Jeffry Fontaine on January 07, 2012, 03:58:46 AM
Looking good!  Would love to see the rest of your WIP on this project. 
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 07, 2012, 04:05:59 AM
I'll post it up soon Jeffry --
Title: Re: McDonnell Douglas AV-19A
Post by: finsrin on January 07, 2012, 10:21:03 AM
Good flowing together of diferent models, looks legit.
See it as low end of high/low (cost) mix of new generation of STOVL fighters.  Force mix of this and F-35.
Title: Re: McDonnell Douglas AV-19A
Post by: John Howling Mouse on January 07, 2012, 11:51:33 AM
And, knowing you, every technical aspect from the theoretical pitch-roll controls to the CoG are perfectly thought out!!  ;)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 08, 2012, 12:14:58 AM
And, knowing you, every technical aspect from the theoretical pitch-roll controls to the CoG are perfectly thought out!!  ;)

Weeeell !  -- I had given it a bit of thought    :icon_meditation:
Title: Re: McDonnell Douglas AV-19A
Post by: Brian da Basher on January 09, 2012, 07:06:33 AM
Yowsa that's looking good, kitnut! You've got some serious design skills!

Brian da Basher
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 09, 2012, 07:41:14 AM
Thanks BdB ---

for this project I took a bunch of parts from these below and jumbled them around a bit. I've got in 1/72, a F-15, F-18, a Tonka and AV-8B and in 1/100 another F-15. Also a fan front from a 1/144 767
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 11, 2012, 03:31:51 AM
For the longest time I've been trying to come up with a plausable way to make a Harrier supersonic.  I've read all about the various methods that were design to accomplish this, from a PCB Pegasus modified Harrier, through the HS P.1154 to the BAe P.1214/1216 projects.  I've read somewhere that RR even proposed a much more powerful Pegasus with thrust output upped to between 30,000 and 35,000 lbs.  This invovled many refinements to the existing Pegasus and also an increase in the fan diameter of around 3-4 inches more than the standard Pegasus and keeping with the cold/hot nozzles idea.  It wasn't proceded with because the whole engine would have had to be bigger and the GR.5/AV-8B was already well underway at the time, and there just wasn't any room for this engine to fit in the fuselage.

Most of my thoughts had revolved around how to convert a Harrier to have ramp style air intakes but the biggest stumbling block was how to intergrate the swivelling nozzles.  One of my thoughts was to have two smaller engines with swivelling hot exhaust similar to the P.1216 and a rear fuselage like a Jaguar or Phantom but placing the cold nozzles always proved to be a problem.  That was until the F-35 came along which is an aircraft I really like (one of the few I think), the cold air louver system seemed to me a really clever way of duplicating what the swivelling nozzles do, the only thing that I don't like about the F-35 system is the horizontal fan, gearbox and driveshaft, too much dead weight being dragged around for 90% of any mission and all the space that could be used for other equipment.  Still I like the approach the F-35 has gone in but don't get me wrong, I still love the Harrier.

I'm not sure when I started to rethink how to make a supersonic Harrier but I began to realize it would have to be a totally different design.  And it would have to revolve around the engine which would have ramp style intakes (my favorite system).  An idea started to form in mind while I was working on another project where I'm planning on making an Avro Atlantic powered by turbofan engines with fan diameter about the same as a Harrier's and installing them into a Vulcan wing.  This involved some new ducts and engine bays with the bypass air exiting above and below the wing.  It dawned on me that a regular type of turbofan would be a way for my new Harrier and then after studying a number of videos of turbofans on airliners I suddenly thought of a way to use the bypass air for the cold air lifting source.  I had been watching how certain turbofan engines actuate their thrust reversers, one type has the whole rear end of the nacelle move backwards to expose a gap where the bypass air is redirected through.  I thought if the mechanism was used to direct air down some ducting instead of just blasting out the sides I could have a pretty good VSTOL engine.  I also decided almost right away the bypass air would go out two ducts and the hot exhaust would have just one nozzle.  The two cold air ducts would have gimballed louvers on the bottom of my new fuselage and that these same ducts could also control pitch, roll and yaw through the louvers and through a variable area control inside the ducts.  With that figured out it was on to deciding what to use for my model.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 24, 2012, 02:10:57 AM
A question to our more knowledgeable members here, is there a US made equivalent to the Rolls Royce Olympus 103 (of 20,000 lb thrust)
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on January 24, 2012, 02:20:53 AM
I assume you are talking same era?
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 24, 2012, 02:32:02 AM
Not necessarily Greg, but something along the same dimensions though.  The idea behind this project is that the engine still used the cold/hot nozzles of the Pegasus, but more powerful.  I'm thinking either the Olympus 301 (EDIT) was modified into a turbofan, with the fan almost 6" bigger in diameter than the Pegasus fan, or I use a US made engine along the same lines.  I'm thinking the hot exhaust puts out 20,000 lb and the cold air bypass another 25,000 lbs.

Here's a couple of pics of how the engine is, top pic is the difference between the Pegasus fan and the one in this project. Second pic is of the engine core with a row of static blades attached to the front.  Third and forth pic is how it goes inside the airframe. Of course I'm jumping ahead with the build here.
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on January 24, 2012, 02:36:22 AM
I will do a little research for you.
Title: Re: McDonnell Douglas AV-19A
Post by: Jeffry Fontaine on January 24, 2012, 02:52:27 AM
The (Wikipedia) Pratt and Whitney F100 (http://en.wikipedia.org/wiki/Pratt_&_Whitney_F100) is close to what you are looking for in that performance class.  The F401 was a derivative of the F100 developed for the Rockwell XFV-12 prototype supersonic VTOL fighter (http://en.wikipedia.org/wiki/Rockwell_XFV-12). 
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 24, 2012, 02:56:00 AM
Thanks Jeffry, but I forgot to add something, 20,000 lb non-afterburning thrust.  This engine for the project doesn't have an afterburner  ---
Title: Re: McDonnell Douglas AV-19A
Post by: deathjester on January 24, 2012, 05:48:43 AM
Would that be the J-67 ?  The one they proposed for the XF-103 Thunderwarrior?
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 28, 2012, 09:40:34 AM
Would that be the J-67 ?  The one they proposed for the XF-103 Thunderwarrior?

Doing a google on that it sounds about right I think dj   :)

Anyway I've modified my engine a bit, I needed to shorten the exhaust pipe and make the engine a bit longer after reading some other stuff on the internet about various engines.  Although the diameter is close to what I was looking for.

Top pic shows where I added a length in, and the second pic give a certain perspective on the lump.  Incidently, I've seen a photo of an actual Olympus production line which looks a lot like this.  IIRC, Jon posted it in my AV-19 thread on the 'other' forum.
Title: Re: McDonnell Douglas AV-19A
Post by: elmayerle on January 29, 2012, 08:53:09 AM
The (Wikipedia) Pratt and Whitney F100 ([url]http://en.wikipedia.org/wiki/Pratt_&_Whitney_F100[/url]) is close to what you are looking for in that performance class.  The F401 was a derivative of the F100 developed for the Rockwell XFV-12 prototype supersonic VTOL fighter ([url]http://en.wikipedia.org/wiki/Rockwell_XFV-12[/url]).

Er, the F401 was a sibling of the F100, intended primarily for the F-14 and also used in the abortive XFV-12A which turned out to have significant duct loses when scaled up from test rigs.  Way back when I first got into aerospace, I worked for P&W's Florida operation on the F100 and F401.
Title: Re: McDonnell Douglas AV-19A
Post by: elmayerle on January 29, 2012, 08:56:43 AM
For reference purposes, here's a frontal view of something St. Louis was playing with.
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on January 29, 2012, 11:15:04 AM
Any more details?
Title: Re: McDonnell Douglas AV-19A
Post by: elmayerle on January 29, 2012, 12:39:32 PM
Any more details?
Unfortunately, no.  I wish like heck that I did but it does create lots of room for speculation.  I've another drawing from the same source which depicts a stretched Harrier II concept and there's enough information in Heart of the Harrier to make some good approximations for modelling purposes; that one is tempting to do as a CILOP program to keep the USMC's Harriers fully competitive a while longer and would also involve an engine upgrade.  It might be interesting to do along side a developed version of the subsonic AV-16 concept.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 30, 2012, 12:22:23 AM
Here's a sketch of what my thinking is on this engine, it is a turbofan of 45,000 lb thrust, approx' 20,000 lb of hot exhaust the rest made up from bypassed air.  When transitioning into the hover, the bypass air flowing backwards is blocked off and diverted down the two side ducts to the bottom of the aircraft, while at the same time the hot exhaust nozzle swivels downwards too.

Second pic shows where the cold air duct exit on the bottom of the fuselage, just in front of the wheel bays.
Title: Re: McDonnell Douglas AV-19A
Post by: sotoolslinger on January 30, 2012, 01:02:04 AM
That is freakin brilliant and beautiful :-*
Title: Re: McDonnell Douglas AV-19A
Post by: elmayerle on January 30, 2012, 02:11:39 AM
Not too far off from some of the tandem fan concepts out there.  This is looking most interesting.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 30, 2012, 02:44:56 AM
Thanks guys---

My idea is that the USMC approached McDonnell Douglas to see if they could enhance the AV-8B's (which they really like). They wanted it to be able to do more of what it does really well.  McD responded by saying that the Harrier as the Marine Corp knows it was at the end of it's development and to increase it's capability would mean a new airframe design.  McD came back with a design which used elements of all three of their important fighters, the F-15, the F-18 and the Harrier

I've read somewhere that Rolls Royce had proposed a more powerful Pegasus but it had an increased fan diameter (about 3 or 4 inches bigger than the standard Pegasus) and it was too late to incorporate into the new Harrier GR.5/AV-8B because it wouldn't fit inside the airframe so wasn't proceded with. It would have had somewhere between 30,000 and 35,000 lbs of thrust.

With that in mind, I decided that my project would have a bigger engine, the fan diameter works out to be 6" bigger in diameter, and I wanted to use the F-15 air intakes (my favorite intake system BTW).  I had worked out the area of the Harrier intake and the F-15 intakes and found that two F-15 intakes would work for the engine I'm thinking about, but slightly reduced in size.  So keeping with already proven designs, I thought a scaled down F-15 wing would work for this project, I found that a 1/100 scale F-15 wing was still bigger than a 1/72 AV-8B wing.  So that where the idea all developed from.

Here's another couple of pics of the project further into the build which shows the two wing sizes.  The AV-19 is a bit bigger than an AV-8B but almost the same size as a TAV-8B

I chose the designation AV-19A because while researching what I could call it, I found that McD had been reserved the number V-19 for a VTOL project.  I thought that was too much of a coincidence not to go with it.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: ChrisF on January 30, 2012, 08:17:40 AM
Coming along nicely... I wish i was as confident at hacking up stuff :)
Title: Re: McDonnell Douglas AV-19A
Post by: elmayerle 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.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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
Title: Re: McDonnell Douglas AV-19A
Post by: elmayerle 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.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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
Title: Re: McDonnell Douglas AV-19A
Post by: finsrin 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   :)
Title: Re: McDonnell Douglas AV-19A
Post by: tc2324 on January 30, 2012, 08:12:32 PM
Great looking concept and very surprised that it`s size is similar to the Harrier.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 30, 2012, 09:58:36 PM
Thanks everyone ---

Here's a pic comparing it to a 1/72 F-15
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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
Title: Re: McDonnell Douglas AV-19A
Post by: ysi_maniac on March 10, 2012, 12:49:57 AM
Most interesting!
Title: Re: McDonnell Douglas AV-19A
Post by: Rafael on March 10, 2012, 08:41:18 AM
100% Pure, unadulterated awesomeness!!!  8)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: ysi_maniac on June 02, 2012, 02:15:20 AM
Top Notck whiffery! :)
Title: Re: McDonnell Douglas AV-19A
Post by: Tophe on June 02, 2012, 01:18:13 PM
Looking good!
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 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.
Title: Re: McDonnell Douglas AV-19A
Post by: Litvyak on June 02, 2012, 10:26:04 PM
This is brilliant stuff! Concept to execution, I love it. :)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on June 02, 2012, 10:28:22 PM
The benefits of using the F-18 forward fuselage is there's a ready made u/c bay which solves another problem of where to put the u/c gear which is catapult launch capable.  Now the plan was to use just the lower half originally but then I saw that I could use some of the top half too.  The two parts have a 'Z' shaped mating arrangement where the front thins down so the first thing to do was make the Harrier cockpit fit the F-18 lower half.  I did this by first glueing the Harrier parts together , then carefully measuring a cut line that matched the F-18 mating surfaces (top pic) then I added the cockpit tub to hold the parts together easier (second pic)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on June 02, 2012, 10:30:38 PM
This is brilliant stuff! Concept to execution, I love it. :)

Thank you very much Ma'am!    :D
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on June 02, 2012, 10:41:50 PM
After getting the parts matched, I discovered that the nose cone on the Harrier is wider at the fuselage joint than the F-18's, I was pondering how I would make the F-18 part match the Harrier's but then I thought, just make the harrier part match the F-18's.

There's a point on the both fuselage parts where they are the same width so I made a mark on both sides where this was, I then glued a portion of the Upper forward F-18 fuselage to where it should go and then glued the nose cone on.  I then cut a diagonal cut from the top of the nose cone join line to the marks on the side of the fuselage (top pic).  I then cut the Harrier parts to suit (second pic).  What surprised the heck out of me, was the neatness of the join, there was practically no sanding what-so-ever to do after the parts were glued together. Third and forth pics are showing the results, and I've placed the canopy on so I could get a visual of it all.  I've also glued a portion of the F-15 rear canopy fairing in place just behind the Harrier canopy, this will be the beginning of the top of the fuselage going back to the rear fuselage.
Title: Re: McDonnell Douglas AV-19A
Post by: Brian da Basher on June 02, 2012, 11:02:14 PM
Now that's some brilliant engineering and magnificent work, kitnut!

I really appreciate your analytical approach which seems to pay off nicely!

Wouldn't this look great in a Golden Hawks scheme? All sleek and shiny!

Brian da Basher

Title: Re: McDonnell Douglas AV-19A
Post by: taiidantomcat on June 02, 2012, 11:48:45 PM
I would have thought this impossible if I wasn't seeing it right now!!  :o

Amazing work  :)
Title: Re: McDonnell Douglas AV-19A
Post by: Sentinel Chicken on June 04, 2012, 12:06:11 AM
The precision of the cuts is great. I like to attack parts with a Dremel and a coarse grinding tool. Very brute force. Your work is much more precise and great to follow along on this project.
Title: Re: McDonnell Douglas AV-19A
Post by: cthulhu77 on June 04, 2012, 12:42:57 AM
Awesomeness !!!!
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 07, 2013, 05:00:35 AM
Well, now that I've managed to finish a project completely (Seafire Hybrid Mk.45), I'm resurrecting this one.  It's almost complete so shouldn't be much to do.  This has a lot to do with me getting my workbench into my hobby room where I can now disappear into for a couple of hours before going to bed.  I found I could get a model done fairly swiftly this way.

One of the things that I had to work out was the undercarriage.  My initial plan was to use the parts from the Airfix Tornado, but they look terrible undersized and fragile.  I purchased an Aeroclub replacement set, but although they are in white metal, they are also way to skinny for my liking.

After a lot of searching on the internet, I found a few photos of the set-up and then I decided to try and make my own main u/c gear.  In the end I got it to look like this.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 08, 2013, 02:34:39 AM
Here's a couple of pics of the model on the Airfix landing gear, you can see it looks really spindly.  Third pic is the Airfix gear and the Aeroclub replacement ones, not a lot of difference and photos of the real things show that they're quite a bit more bulky than these.  Forth pic is those u/c legs with the one I've fabricated.

I'm using all the F-18 wheels for this too.
Title: Re: McDonnell Douglas AV-19A
Post by: deathjester on January 08, 2013, 02:50:49 AM
Really nice work!  If only that was available as a kit - I'd buy those for sure!  :)
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on January 08, 2013, 03:26:16 AM
Looking good
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 08, 2013, 05:09:28 AM
Thanks guys --
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 09, 2013, 12:46:39 AM
OK, I've got a designation for this, AV-19A, now I need a name.  Has to be some raptor type bird that can hover name and American.  I'm thinking Buteo ( which are Buzzards)  at the moment. Or we could go with Kestral II ---  but as this is almost twice as big as the original Hawker Kestral I'm not sure about it.
Title: Re: McDonnell Douglas AV-19A
Post by: Logan Hartke on January 09, 2013, 01:34:11 AM
Well, nobody uses "buteo" in the US at all.  "Buzzard" (the name for buteo in Europe ) has a negative connotation in the US, generally referring to vultures, not hawks.  In short, a US aircraft company is unlikely to name an airplane "buzzard".

My suggestion?  Harpy.  The harpy eagle is one of the largest, most powerful birds of prey in the Americas.  It's not as common a hovering bird as the kestrel, harrier, or osprey, but it can hover for short period of time (as far as I know).  Furthermore, it fits with McDonnell's history of "paranormal" names with its roots in the mythological "harpy".

(http://www.royle-safaris.co.uk/wp-content/uploads/2012/08/harpy-eagle-panama-1024x768-847266.jpeg)

Cheers,

Logan
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 09, 2013, 04:08:32 AM
Thanks Logan, that's one to store in mind ---  :)
Title: Re: McDonnell Douglas AV-19A
Post by: Volkodav on January 09, 2013, 03:24:50 PM
Harpy, I like it, sort of implies swooping through trees plucking prey from the branches with impunity.
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on January 09, 2013, 04:04:19 PM
Harpy:

(http://images4.wikia.nocookie.net/__cb20070826185121/wowwiki/images/5/56/HarpyMG.JPG)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 09, 2013, 10:02:19 PM
I had envisions of something like that too Greg --- only much uglier with all the warts and bumps LMAO!

Can you send me a scan of that, I'll see if I can make a decal out of it ---
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on January 10, 2013, 02:27:39 AM
I had envisions of something like that too Greg --- only much uglier with all the warts and bumps LMAO!

Can you send me a scan of that, I'll see if I can make a decal out of it ---

It was just something I found on the internet (just did a Google Image Search on "Harpy") - you can probably just download it by copying the image I have shown here.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 16, 2013, 01:54:18 AM
I got the engine in but decided not to mess around with it too much.  Although you can see up the tunnel, you can't see very much detail wise (top pic)

Then I got the upper rear bodywork on and after a couple of rounds of PSR, got it to this stage.  A bit more PSR and I can get a coat of paint on the top to see what I have to fix
Title: Re: McDonnell Douglas AV-19A
Post by: Brian da Basher on January 16, 2013, 08:04:29 AM
I'd say you totally nailed that engine modification, kitnut!

Yes your Harrier will indeed be Super!

Brian da Basher
Title: Re: McDonnell Douglas AV-19A
Post by: flappydaffy on January 19, 2013, 08:37:47 AM
nice plane and challenging build... but what I like the most is how with one plane you are able to significantly reduce the level of your stach ^^

looking forward for the next steps :)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 28, 2013, 03:07:51 AM
So in between rounds of PSR, I've made up another major step in the build, I've done the cold air ducts.  I drew out the shape and then developed all the parts.  These I printed off and stuck it to some styrene (top pic).  I decided to make these like this because the ducts are quite large and you can see well into them once they are installed.

So after I cut and bent the shapes I started to glue them together (second pic) and then finished them off by closing the side up and then adding a thin strip of styrene around the open side. This is to represent the frame that the control vanes will be attached to, in my idea this frame is gimbled to rock side to side (third & forth pic)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 28, 2013, 03:09:50 AM
And this is how it looks now that the ducts are glued in to the model, I've painted around them so I can see what needs tidying up.
Title: Re: McDonnell Douglas AV-19A
Post by: Brian da Basher on January 28, 2013, 05:42:31 AM
Those new ducts look like a million bucks, kitnut!

Following the play-by-play on one of your projects is more fun than cable TV!

I can't wait to see what's next with this one!

Brian da Basher
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 29, 2013, 06:18:29 AM
Thanks BdaB, my son was watching me do this over the weekend and he said to me, ' this would be neat if you were building it in 1/24 scale and make everything work as you think it should'. 

Got me thinking that ---  1/32 maybe -----
Title: Re: McDonnell Douglas AV-19A
Post by: ChrisF on January 29, 2013, 08:06:51 AM
Ya better finish this one first !

Maybe call it practice ? ;)  lol
Title: Re: McDonnell Douglas AV-19A
Post by: elmayerle on January 29, 2013, 09:31:00 AM
And this is how it looks now that the ducts are glued in to the model, I've painted around them so I can see what needs tidying up.
Very nice and quite elegant.  Do the cold flow ducts have variable vanes at their exits to give a limited amount of vectoring?  I'm thinking back to the cold exhaust nozzle vanes on the F-35B.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on January 29, 2013, 10:31:21 AM
And this is how it looks now that the ducts are glued in to the model, I've painted around them so I can see what needs tidying up.
Very nice and quite elegant.  Do the cold flow ducts have variable vanes at their exits to give a limited amount of vectoring?  I'm thinking back to the cold exhaust nozzle vanes on the F-35B.

Thanks Evan, and yes that is what I'm thinking of, there will be about five of them on each duct. The idea is they will be able to rotate so they point five or ten degrees forward so that when in the hover the aircraft could move backwards (like a Harrier) and then they will rotate totally backwards until they close off completely and shut the duct off for forward flight.  And because the vanes are mounted on a hinged frame where the hinge centers are orientated for/aft, there's a certain amount of rocking that can direct the air stream to the sides, which will work in hand with the yaw control of the hot air nozzle. 

The idea is that all the controls for hovering go through these ducts and the hot exhaust nozzle instead of having 'puffers' like the Harrier has.  I had thought that something like an area control actuator in the duct that would vary the pressure in each duct for roll control, but I've had another thought.  I think what it needs is an actuator controlled vent on the top side of the fuselage and when the aircraft goes into the hover, these vents would be partially open so air would be always exiting upwards but only when in the hover.  For the roll control, these vents would either open or close opposite to each other, then for pitch up these vents would close off, and for pitch down they would fully open.  By doing this the vents would raise or lower the pressure in each duct and of course be infinitely variable.

Once all the PSR is finished and I get all the u/c on, I'll add these vanes to the ducts.
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on February 02, 2013, 03:21:05 AM
Ya better finish this one first !

Maybe call it practice ? ;)  lol

A scale model of his scale model... ;D
Title: Re: McDonnell Douglas AV-19A
Post by: ChrisF on February 02, 2013, 08:25:56 AM
Ya better finish this one first !

Maybe call it practice ? ;)  lol

A scale model of his scale model... ;D

Dont pretend you havent at least thought of it yourself ;)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 11, 2013, 01:11:20 AM
Got a bit more done, I've worked on the exhaust nozzle now.  I've made two, one as in forward flight and one for in the hover.  I've made them so they're a friction fit into the rear end of the engine, this way I can display the model two ways although the doors will always be in the down position.

Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 11, 2013, 01:15:09 AM
I wanted them to have an appearance of having stiffeners on the outside of the pipe so I drew up some shapes which I then printed on sticky-back paper, then stuck to styrene (top pic).

I then cut them out leaving one staying all attached (2nd pic) and the other I split into sections (3rd pic)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 11, 2013, 01:21:16 AM
For the straight through pipe I just glued the joined shape to some brass tubing but I used some aluminum tubing with thicker wall for the turned down pipe.  This was so there was more contact area for super glueing at the joints.  I forgot to take some pics of the straight pipe during fabrication, but it was similar to how I did the turned-down pipe. Top pic shows the two together but with no stiffeners on the turned-down one.  2nd pic is just a scale comparison with a quarter (about the size a 5P coin for our friends on the other side).  3rd pic is of the stiffeners glued on
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 11, 2013, 01:24:21 AM
Here's how it looks in the model, top pic is of the straight pipe attached to the engine, you can see I've cut the doors off the rear fuselage.

The others are with the turned-down pipe in place.
Title: Re: McDonnell Douglas AV-19A
Post by: Brian da Basher on February 11, 2013, 02:57:10 AM
Those are some amazing details, kitnut! By the time you're done, you'll have everyone believing your AV-19A was real!

Brian da Basher
Title: Re: McDonnell Douglas AV-19A
Post by: taiidantomcat on February 11, 2013, 04:10:03 AM
Holy cow! excellent craftsmanship!
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 11, 2013, 08:12:21 AM
Thanks guys, the photos are really showing up the flaws though, it doesn't look as rough when I'm looking at the parts ----hmm!!
Title: Re: McDonnell Douglas AV-19A
Post by: elmayerle on February 11, 2013, 10:21:15 AM
Still looking good so far.  I suspect the photos provide you with enough distance that you can see what needs tweaking, but I certainly don't see anything wrong.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 11, 2013, 11:34:09 PM
Thanks Evan ---

Just a technical note,  I used round tube because in this scale it's easier to use (and get by with) but in the real world, the sections of pipe are not actually round, at least that's how they develop out as when I draw it correctly.  The reason is the angled connections are actually round because there's a bearing race there which means the short straight section parts are a round to angled round tranistion, and the middle straight section  is really an elipse in shape

This below might help with the explanation.  If you cut a round pipe at an angle, the resulting cut face is an elipse, in reverse, if the angle cut is actually round then the piece of pipe is really eliptical in shape
Title: Re: McDonnell Douglas AV-19A
Post by: Eddie M. on February 12, 2013, 07:51:49 AM
Absolutely stunning work. Nice to see your work again. :)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 13, 2013, 07:27:18 AM
Hey Eddie, where've you been --- thanks for your kind words   :-[
Title: Re: McDonnell Douglas AV-19A
Post by: Eddie M. on February 15, 2013, 05:45:11 AM
Wondering aimlessly through the void looking for my mojo. Haven't completed a model in over a year, but still chipping away at many. Got a whif Super Hornet that's so close to being done I can taste it. But, as in a bad dream, I just can get there. Maybe I should hang out here more.  ;)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 15, 2013, 06:16:44 AM
Wondering aimlessly through the void looking for my mojo. Haven't completed a model in over a year, but still chipping away at many.

I know where you're coming from, only manage to do one in over 18 months I think (Supermarine Seafire (Hybrid) Mk.45) but that got me back onto this one.  I'm going to make a big effort to finish a few that are mostly done but got shelved because I moved on to something else.

Maybe I should hang out here more.  ;)

See, there's the answer ---  ;)
Title: Re: McDonnell Douglas AV-19A
Post by: Eddie M. on February 15, 2013, 06:36:03 AM
I must admit, a certain social website was occupying a lot of my time and I decided to deactivate that so that I might actually get back to having a life and hobby.  ;)

Now, if I could just find the cowling to the bird I'm working on. A new cat in the house and he's trying to derail my comeback. ;D
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 18, 2013, 05:05:18 AM
Nothing much in progress at the moment, got a bit busy.  But I did glue the tail surfaces on and sorted out the canopy.   If anyone has built an Airfix Harrier GR.5/7 they would know that the canopy is just way too wide for where it's supposed to go.  I thought I had figured out what to do, I carefully squeezed it in and glued a small strip of styrene to the bottom edge to hold it in shape. I then glued the windshield on, leaving it overnight to make sure it cured properly.  Next day I saw all these little stress fractures had appeared all over the top of the canopy so I thought I would stress relieve it.  I put it in a cup of water and then zapped it in the microwave, weelll -- it didn't go to plan  --- it shrunk into a little blob of plastic --  so that was the end of that.

I'm now on my last canopy set from an Airfix GR.5/7 kit and what with some that were broken already and others which ended up broken, all from trying to get it to fit onto a fuselage, I've now got four of them which have no canopy ---  and there's no aftermarket product to get --  :-X :-X  Looks like I'll have to try and do one myself --
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on February 18, 2013, 05:18:32 AM
Nothing from a vacuformed pov?
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 18, 2013, 05:28:45 AM
Nothing from a vacuformed pov?

No there isn't anything out there and considering the problems with the canopy from this kit I find that surprising as every one of the Airfix GR.5/7 are like this that I've come across, and even the T-10 kit has the canopy sections too wide too.  I don't know if it a situation where over time the canopy sort of stress relieves itself and goes out of shape, but when I pulled the blob of plastic out of the hot water I was somewhat surprised by the result.

My last canopy I've got comes from the Airfix Club kit, Sea Harrier and GR.7.  I carefully squeezed this one to fit the windshield part and just glued the windshield on it, and stress fractures are already appearing on the canopy part.  Really odd ---
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on February 18, 2013, 05:39:04 AM
Would it be better to use the existing canopy as a modl to make some Vacuform/smash form canopies?
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 18, 2013, 05:41:49 AM
Would it be better to use the existing canopy as a modl to make some Vacuform/smash form canopies?

I think that's what I'm going to do Greg, only I've got to buy another Airfix GR.7.  Maybe I'll get the new GR.9 kit and see what I can do with that. I think though, I'll make a resin mould and vacuform it correctly, I've been studying the moulds I have for the Victoria Products 1/72 Avro Arrow and that's what they did there.
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on February 18, 2013, 05:46:17 AM
Maybe you should make a whole bunch and sell any you don't use.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 18, 2013, 05:48:48 AM
That had come to mind ----  ;)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 23, 2013, 05:31:34 AM
A bit more progress,  I had to modify the u/c bay doors (top two pics) and I decided the tail planes I was going to use didn't look quite right. So I made some slightly bigger ones instead (bottom two pics)
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 23, 2013, 05:33:25 AM
I'm also playing with a camo scheme which is taken from the Airfix TAV-8B kit, but I'm not sure about it at the moment.  I might change it to something else ---
Title: Re: McDonnell Douglas AV-19A
Post by: taiidantomcat on February 23, 2013, 09:40:04 AM
I like that scheme, It looks realistic
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 23, 2013, 11:38:16 PM
It's beginning to grow on me too ttc, I might extend the darker grey further forward along the fuselage a tad though, but not right up to the canopy
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 24, 2013, 03:48:13 AM

([url]http://www.royle-safaris.co.uk/wp-content/uploads/2012/08/harpy-eagle-panama-1024x768-847266.jpeg[/url])

Cheers,

Logan


I liked Logan's idea, I've got some decals coming of this. They will go on the outside of the fins. It will be just the head though ---
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on February 24, 2013, 04:06:16 AM
This just gets better and better...
Title: Re: McDonnell Douglas AV-19A
Post by: Brian da Basher on February 24, 2013, 04:33:20 AM
This just gets better and better...

I couldn't agree more! Here's wishing you the best of luck on the canopy issues, kitnut!

Brian da Basher
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 24, 2013, 04:40:50 AM
Thanks guys --

I think I'll stick with this canopy Brian for this project, but what I'm going to do with the other GR.5/7's that are now missing a canopy I don't know just yet.  I do think there's a market for an aftermarket alternative though.  I've found that Heritage Aviation do a very nice 1/72 T.10 conversion for the new Airfix GR.9 kit, and Ian has been very obliging in the past when I've asked for various bits he produces so there's a possibility for replacement canopies for the Airfix/Heller T.10's that I have.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 24, 2013, 06:29:16 AM
I dug out my F-15E model and here's a couple of pics comparing the F-15E, TAV-8B (actually a T.10) and the AV-19A for size.
Title: Re: McDonnell Douglas AV-19A
Post by: GTX_Admin on February 24, 2013, 06:30:07 AM
Oooo..I do like that F-15E.
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on February 24, 2013, 06:37:39 AM
Thanks Greg, IIRC it's the Monogram F-15B to E prototype kit.  It came with some pretty crumby weapons so I added a bunch of Hasegawa iron 500 lb'ers to the MER and a target designator and 2000 lb guided bombs.  The kit came with the 30mm rotary cannon pod so that stayed where it was on the center pylon.
Title: Re: McDonnell Douglas AV-19A
Post by: Logan Hartke on February 24, 2013, 09:33:58 AM
This is looking great.  Very natural!

Cheers,

Logan
Title: Re: McDonnell Douglas AV-19A
Post by: kitnut617 on March 20, 2013, 04:59:34 AM
Would it be better to use the existing canopy as a modl to make some Vacuform/smash form canopies?

I think that's what I'm going to do Greg, only I've got to buy another Airfix GR.7.  Maybe I'll get the new GR.9 kit and see what I can do with that. I think though, I'll make a resin mould and vacuform it correctly, I've been studying the moulds I have for the Victoria Products 1/72 Avro Arrow and that's what they did there.

I've just had a good look at the new tool Airfix GR.9 Harrier kit, it looks like Airfix has addressed the canopy problem their previous GR.5/7 had because it's moulded quite differently. I think I'll try using this one to make a bunch of others ---