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USA Build: A4D-1 (A-4A) Skyhawk, circa 1956, Southern California

An early Scooter in service with the US Navy Reserves at NAS Los Alamitos

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John H. Rood08/03/2018 16:08:42
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195 forum posts
274 photos

Cheers, guys. The elves and mini-erks here at the imaginary Douglas Skyhawk factory have been busy, and the sawdust has been flying.

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Why is the imaginary avionics compartment open? Through trial and error I wound up going with my original intuition, that I'd be best off making a pretty dang SOLID balsa nose on this first attempt at an early A-4 Skyhawk.

At first I thought I could just begin that from bulkhead F1 position forward, but as the nose datum is completely different and the curve between F2 and F1 was resulting in a what I believe will be a too-fragile compartment there, so I have decided to go back in there and beef-up that area from the inside-out. Also I just wasn't happy with the way the shape was emerging, -- the fattest part was too low relative to datum.

So, I pulled out the surgeon's scalpel and all is going well: I've kept the hardpoints and hardened the nicely-curving sheeting at the undersides via sloshing around drops of thin cyano. Works great so far.

Another issue that emerged was that last week amidst the ammonia elixir I somehow overlooked an important step: adding the 1/2" balsa triangle stock to the upper area between F3 and F3.

So the "starved horse" look I mentioned earlier, well, it never really went away, and in fact I wound up with that F3<->F2 compartment looking all wrong on top -- pulled in wayyy too narrow.

So that will be next installment, correcting that lil' snafu.  I'll either will add skin on the outside or go from the inside.  Also plenty to do still with the routine fine tuning of low and high areas on the fuselage, such as adding a slight fill to the belly just aft of the wing TE.   All good. Having a blast here cutting balsa and making a mess everywhere.

And speaking of fun, who doesn't love the beginnings of a jet tailpipe? fist

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Edited By John_Rood on 08/03/2018 16:13:28

John H. Rood08/03/2018 17:35:41
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195 forum posts
274 photos

F2_and_av_bay.jpeg

More photos re: the above post:

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John H. Rood10/03/2018 02:13:10
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195 forum posts
274 photos

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John H. Rood10/03/2018 02:31:16
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195 forum posts
274 photos

Love the look of the Douglas Skyhawk!

Plenty more to do, but the nose shape is now finalized and she just needs a 1/2" balsa panel to cover the ersatz "avionics bay" and a few zillion other little things. Great fun being had here.

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Piers Bowlan10/03/2018 05:42:38
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1868 forum posts
44 photos

Nice rear end there John, if you will pardon the expression blush. I guess I could have done a bit more sanding on mine but too late now as it is mostly covered in film. I did buy some ammonia but found I could get away without it but I did use some man-sized clamps to torture the balsa with.

Edited By Piers Bowlan on 10/03/2018 05:46:54

Phil Cooke10/03/2018 06:51:22
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2252 forum posts
1539 photos

Great progress John!! Looking good with the wing and tail in place for the camera! smile d

John H. Rood10/03/2018 11:27:32
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195 forum posts
274 photos

Thanks, gents. Great fun!

Piers, I believe I’ve sanded too much off in some areas. So I’ll add some soft 1/16 sheet to correct those low/thin spots. For example, her belly just aft of the TE can use a bit more girth.

Next will be to correct my aforementioned construction error between F3 and F2: her shoulders are too narrow.

Then I’m to add the engine intakes — and REALLY give that ammonia a workout!

John H. Rood10/03/2018 11:40:11
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195 forum posts
274 photos

This Point Mugu A4D-2 (A-4B) shows the belly curve we crave!

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Edited By John_Rood on 10/03/2018 11:41:49

John H. Rood10/03/2018 14:49:27
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195 forum posts
274 photos

Apparently I strayed from Phil's build sequence, and I might just make those intakes now, and then see what next I should do with filling everything in and resolving my upper shape deficiency between F2 and F3.

Ref: his build page 5 http://www.modelflying.co.uk/forums/postings.asp?th=115393&p=5

Also I shall cut out the canopy and that may also help me get a better picture.

Edited By John_Rood on 10/03/2018 14:51:49

John H. Rood10/03/2018 18:22:26
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195 forum posts
274 photos

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That blue line in the "avionics bay" is the datum for the the early A-4 nose shape.  I used it here to help me toward getting the nose config reasonably correct.

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And then this very strange alien creature landed on the deck... the shadow is positively H.G. Wells-worthy!

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Edited By John_Rood on 10/03/2018 18:27:18

John H. Rood10/03/2018 20:38:13
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195 forum posts
274 photos

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Until today I had absolutely no idea that these two-part plastic wine glasses for camping, hiking, picnics -- ACTUALLY WERE DESIGNED SPECIFICALLY FOR MOLDING A-4 SKYHAWK ENGINE INTAKE SKINS?

They are a PERFECT fit!

yesyes

McG 696910/03/2018 20:52:48
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2539 forum posts
973 photos

Hi john,

Following your A4 build with interest, but something makes me thinking that you had a serious 'overdose' of ammonia some time ago... "alien creatures? ... "H.G.Wells ...???

I've never heard of 'wine glasses' - even very common plastic ones - being at the origin of the air intakes of the Skyhawk...

But I guess the designer himself could have the final word to conclude this matter.

As they say in French, "A votre bonne santé"

or... Cheers

Chris

John H. Rood18/05/2018 00:11:58
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195 forum posts
274 photos

JUST A TEST: Posting a pic via my flickr account.

This one was back on 6th March 2018.

6 March 2018 Ridiculousness

John H. Rood20/09/2018 17:36:42
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195 forum posts
274 photos

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18 Sept 2018 and back in the fray.

Adding balsa bits here and there toward final-shaping the fuselage.

Phil Cooke20/09/2018 18:57:57
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2252 forum posts
1539 photos

good to see the Boston Scooter back on the bench John! thumbs up

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John H. Rood20/09/2019 16:32:13
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195 forum posts
274 photos

Seems the last time any build progress happened here, colour photography hadn't yet been invented? Shameful, but I'm back at her now. Thanks, all, for your patience.

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Joiner

Back at it now! Morning sun earlier today and The Douglas Tech Rep in deep meditation this morning before a mysterious MONOLITH from "2001: A Space Odyssey", serving now as a *new* and *full-depth* 1/16th ply dihedral brace/wing joiner for the Skyhawk:

Monolith Meditator

Dry-fit came out OK. Next is to attach the aileron torque rods and the inboard TE.

Wing Status.upper as of 20th Sept

Wing Status.underside as of 20th Sept

Earlier, one of The Tech Rep's able engineers evaluates A4D-1 Skyhawk curve radii; this was before the introduction of the refueling probe. Note her footwear, crucial to proper Skyhawk test procedurals and PSS search & rescue maneuverings...

Douglas_Tech_Rep

Phil Cooke20/09/2019 19:56:20
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2252 forum posts
1539 photos

certainly a nice looking way to polish your nose cone

John H. Rood21/09/2019 04:06:50
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195 forum posts
274 photos

Attaching the aileron torque tubes with JB Kwik epoxy. The stuff’s a dark sticky grey-black mess so I decided to mask off the surrounding area.

Prior to this I had to refurbish the torque rods as it has been so long they’d become oxidized/corroded/whatever and were not moving freely. Gave ‘em a thorough cleaning and light lube with machine oil, and trimmed everything to size. Scuffed the outside of the torque tubes and routed out a channel in the balsa for to seat them in snug.

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John H. Rood21/09/2019 18:38:46
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195 forum posts
274 photos

Wing Trailing Edges: channel routing and rough-sanding now pretty much complete; tip washout looks good so far; aileron torque rods are doing their thing.

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John H. Rood22/09/2019 04:53:19
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195 forum posts
274 photos

Just about “there” with sanding the TE ass’y to shape. Quick dry-fit of the goods for the neighbors.

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