John H. Rood Posted March 6, 2018 Share Posted March 6, 2018 On The Importance Of *NOT* Doing What I Do, #1,789: Do NOT use push-pins "down low" -- as I done did! ((( Can I re-vision it as, ummmm... "shrapnel over the Mekong Delta"? ))) Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 6, 2018 Share Posted March 6, 2018 Using Ammonia to Correct the Dreaded "Starved Horse" Look: As the nose skins dried to shape I noticed I'd introduced a bit too much pull-in on them up towards the top, just aft of bulkhead F2. So, I re-soaked the entire area in ammonia, inside and out, placed the soaked paper towels inside the fuselage, and added more paper towels, and more, and more, until I was gently but firmly "packing" the interior to create outward pressure within there. Meanwhile I used my eyes and hands to feel my way to a more suitable exterior curve, a more Skyhawk-like curve. We'll see how she turns out as everything evaporates and fully dries out. So far so good. And I've been pleasantly surprised at how little problem I've had with the ammonia fumes; I've been dreading the thought of it for a year and half and jeeze it was no big deal. Sez the guy with permanent lung/brain damage and an aeromatically-fuzzy future. Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted March 7, 2018 Share Posted March 7, 2018 She's getting there Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 7, 2018 Share Posted March 7, 2018 Last night I dreamt I was building a scale model of a combination submarine, Hound Dog missile, and Russian oligarch's yacht (complete with BOTH a heli pad AND an angled carrier deck. Oh! The power of ammonia, sawdust, and Jules Verne, unchained. Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted March 7, 2018 Share Posted March 7, 2018 The ammonia works really well and you can never, ever have too many clamps of any/all sizes. Buy lots more! Having never used it before building the A-4 I was also wary of what the smell and effects of ammonia on skin/eyes/nostrils would be but like somebody said it only really smells when it's wet! Looking good and tidy there John. Just need to fill those pin dents. You really did push them right in! Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 8, 2018 Share Posted March 8, 2018 Cheers, guys. The elves and mini-erks here at the imaginary Douglas Skyhawk factory have been busy, and the sawdust has been flying. 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? Edited By John_Rood on 08/03/2018 16:13:28 Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 8, 2018 Share Posted March 8, 2018 More photos re: the above post: Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 10, 2018 Share Posted March 10, 2018 Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 10, 2018 Share Posted March 10, 2018 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. Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted March 10, 2018 Share Posted March 10, 2018 Nice rear end there John, if you will pardon the expression . 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 Quote Link to comment Share on other sites More sharing options...
Phil Cooke Posted March 10, 2018 Author Share Posted March 10, 2018 Great progress John!! Looking good with the wing and tail in place for the camera! Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 10, 2018 Share Posted March 10, 2018 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! Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 10, 2018 Share Posted March 10, 2018 This Point Mugu A4D-2 (A-4B) shows the belly curve we crave! Edited By John_Rood on 10/03/2018 11:41:49 Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 10, 2018 Share Posted March 10, 2018 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 Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 10, 2018 Share Posted March 10, 2018 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. And then this very strange alien creature landed on the deck... the shadow is positively H.G. Wells-worthy! Edited By John_Rood on 10/03/2018 18:27:18 Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted March 10, 2018 Share Posted March 10, 2018 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! Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted March 10, 2018 Share Posted March 10, 2018 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 Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted May 18, 2018 Share Posted May 18, 2018 JUST A TEST: Posting a pic via my flickr account. This one was back on 6th March 2018. Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted September 20, 2018 Share Posted September 20, 2018 18 Sept 2018 and back in the fray. Adding balsa bits here and there toward final-shaping the fuselage. Quote Link to comment Share on other sites More sharing options...
Phil Cooke Posted September 20, 2018 Author Share Posted September 20, 2018 good to see the Boston Scooter back on the bench John! Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted September 20, 2019 Share Posted September 20, 2019 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. 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: Dry-fit came out OK. Next is to attach the aileron torque rods and the inboard TE. 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... Quote Link to comment Share on other sites More sharing options...
Phil Cooke Posted September 20, 2019 Author Share Posted September 20, 2019 certainly a nice looking way to polish your nose cone Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted September 21, 2019 Share Posted September 21, 2019 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. Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted September 21, 2019 Share Posted September 21, 2019 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. Quote Link to comment Share on other sites More sharing options...
John H. Rood Posted September 22, 2019 Share Posted September 22, 2019 Just about “there” with sanding the TE ass’y to shape. Quick dry-fit of the goods for the neighbors. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.