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gingerbob

Another F-5/T-38 Group Build group build?

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OK, finally something worth showing a photo of: as mentioned in Chat, I concluded that the Kinetic F-5B is a bit short in the cockpit section. So, after careful comparison to photos, the Wolfpack T-38, and a station drawing that I enlarged to 1/48ish, I formed a plan, hopefully thought of those things that sneak up on one, and- before giving myself the chance to come to my senses, did the dirty deed. What remains, of course, is all the clean deeds that come as a result...

This photo shows where I made the cut- the idea is to have it make as little disruption as possible to the cockpit parts (of which more later) while also being in a location that allows re-alignment with little fiddling. We'll see whether I did, in fact, think of those things...

chop_zps4ijsdd8v.jpg

And the second photo shows why I thought it worth doing. Were I just building an F-5B I probably wouldn't have discovered or felt the need, but since I'd already studied the Wolfpack and <cough> Trumpeter T-38s (sorry, those of you building the latter) I was curious about such things. Plus, I just like to make things more difficult for myself, or, as my wife would put it, "ruin another kit". My daughter calls it dissection, which at least sounds more scientific! Anyway, I decided not to crop this one, since it shows the "mad scientist" setting. (Incidentally, for those who don't know the kit, the apparent mis-alignment on the bottom is because there's a separate belly panel there (as you can see in shot above), not because I moved it that much!)

DSCN4914_zpshk4hrmdb.jpg

(original here, if you want the large-print edition)

By the way, the drawing is a reference, I don't put complete faith in it being precisely accurate. But it does help to see if something is in the ballpark, and makes it easier to compare one kit's shape with another's. One of these days I'll show you some examples...

bob

p.s. Notice the nice clean join between aft fuselage and what's left of the front fuselage- liquid cement on the verticals, with rather more super glue than I intended on the inside to reinforce it. I'll run a bead of liquid down the horizontal join eventually.

Edited by gingerbob

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Well, first of all I'll probably have canopies open, which takes much of the pressure off (unless, of course, the cockpit doesn't go well!) My gut feeling is that Wolfpack does the best job getting the "skirt" right, but I might well steal the F-5F's- haven't looked closely at the skirt on those (by which I mean the solid bit below the glass, that flares out to form part of the fuselage shape) but their general shape seems at least as good as the others. And they're a lot easier to come by than spare Wolfpack parts! (I don't much like the prospect of trying to smash-form my own, but if there is a vac option I'd consider that.)

One could probably add some to the back end (and forward?) of the Kinetic parts and do the job- they seem to have too little solid frame in general- but since I've got the various kits I've got more options, and was interested to compare. My advice to the typical sane builder, though, is ignore an alleged shortness and consider it close enough.

EDIT: I just had a peek at the AFV Club F-5F, since I hadn't yet examined its clear parts in detail, and discovered that it comes with alternate rear canopies, so that's another option.

bob

Edited by gingerbob

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You don't like to take the easy path do you Bob!

So what do you intend to do with all the leftover bit if the surgery.....

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The plot thickens... (and Merry Christmas to all)

More evidence about something going on in the cockpit section - from top to bottom,

Kinetic F-5B

Monogram F-5F

AFV Club F-5F

Wolfpack T-38

pits%20side_zpsoidpdaqf.jpg

pits%20above_zpsowmeyl0f.jpg

Lined up, in a casual way, at the central bulkhead. Note how the rear bulkheads are all about the same except the Kinetic.

Now here's the Kinetic fuselage lined up (hopefully at appropriate spots!) with the Wolfpack T-38 fuselage (tailplane hinge point, a couple of panel lines on the aft fuselage, vertical fin panel line; on the front, nose-wheel well (more or less), windscreen rear and panel line). Less of a gap than when the fuselage was laid out on the drawing above (note that the apparent jagged cut is just some sawing "crumbs")...

with%20Wolf_zpswkzg0lyq.jpg

But look what happens when we look from above:

fuselages%20top_zpszk8mru6l.jpg

Hmm, something isn't right about that back edge of the cockpit.

And finally, I managed to find a couple of nearly perfect photos and used my parallel rule to draw a bunch o' lines, the better to compare with, my dear. Before I talk far too much about that, I'll just show it here for those few of you interested enough to draw your own conclusions. By the way, the lovely build of the Kinetic kit uses aftermarket ejection seats, either Wolfpack or "ATML" or something like that (I'll have to go find it again). (Direct link to big version of this image.)

lines_zpsx42iwrsp.jpg

First impression is that this calls into question my claim that the Kinetic needs stretching. And yet, it is possible that something's not quite right, and I keep coming back to the back of the rear canopy. For my own satisfaction, I'm going to have to go back to the station drawing and check the placement of some panel lines, as well as the location of said stations on the drawing. I did notice that the panel lines on the spine of the Kinetic followed a different "schedule" than the Wolfpack, but I don't particularly care, as long as I can identify ones that ARE in the same place on both kits. My goal was to have the Wolfpack and Kinetic kits end up looking (approximately) identical, but in the process I was hoping to gain some understanding about how well each matches the true shape of the aircraft.

Back to present-opening!

bob

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Whoo boy, I'm still studying F-5 dimensions, and on the F-5F I've found three different "tip to tailpipe" lengths quoted on drawings that look like they should know what they're talking about. Best part is, the overall dimension doesn't add up to the station numbers at each end on the same drawing!

I have some Monogram boxes that house my two-seat F-20 project and the "other halves", and I recently shifted the big parts all into one box and the rest into something else, so that I could use the freed-up box for sorting my current F-5 bits. Went looking for the "little bits" this morning, to compare landing gear with the other kits, and I couldn't find them! I have no memory of what I did with them, and it wasn't more than a couple of weeks ago...

In the midst of this chaos, I have managed to tackle the intake trunks on the Kinetic kits. Some of these parts have hefty ejection pins/pour stubs/whatever inside the small-diameter tunnel. Nice. Rummaging through my Dremel case I found a cone-shaped small thingy, and that did a great job of knocking these down. Followed that up with a bit of scraping (and carving off some "bumps") with the XActo, and liquid-glued the pairs. One piece was a bit warped, but behaved with a bit of pressure- hope it didn't twist the pipe in a way that'll come back to haunt me, but I doubt it. I'm hoping that any remaining roughness will be far enough into the tiny tube to be invisible.

Hopefully back before too long with photographic evidence of progress...

bob

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Time for a bit of a comparison- the usual caveat that the drawing may not be perfectly accurate, but it certainly serves as a basis for comparison:

(Here's the link to my photos should anyone wish to look closer. Actually, I'm not sure if these are any smaller than the originals. Now that I look at the post on my screen I wonder if I should have made them smaller- I wanted you to be able to see the details.)

First, for the record, Fujimi: This is a very basic kit and (I would suggest) no longer worthy of serious consideration

Fujimi_zps5byanymx.jpg

Next, Monogram. This is the F, but I would anticipate that the E is virtually identical (I cut the nose off for a two-seat F-20 conversion). Note that the wing to tail length is the same (essentially) as the F-5A/B, but the added section at the center can be seen by how the tail is offset from the drawing. (Note also that this kit features the original (for E/F) LEX. Also, this part didn't sit quite flat on the paper, and some apparent deviation may be owing to that. I propped up the starboard wingtip to try to keep it as close as I could.)

Monogram_zpsbgzklmtz.jpg

Now the Kinetic wing on the Monogram... and directly on the drawing (the root shape, or intersection with the fuselage, changed somewhat on the E/F)

Kinetic%20on%20Monogram_zpsczzyd4a6.jpg

Kinetic_zpsal6fqqop.jpg

Note that it appears that Kinetic's leading-edge flap has too much chord- it is supposed to follow the 15% chord line. It may be a wee bit off in other ways, too, but nothing that really leaps out at me as "needing" to be fixed. I might have to do something about the L.E. flap, though... Compare to the AFV Club wing (remembering that this is for an E/F- the LEX, obviously, is a separate piece.)

AFV%20Club_zpsu9umyxcd.jpg

And meanwhile, back at the T-38... Wolfpack:

Wolfpack_zpsnzzy9bh7.jpg

and with Kinetic:

Kinetic%20on%20Wolfpack_zpspkrfot33.jpg

Finally, the photo of the Trumpeter wing alone apparently failed to take, but this one with the Wolfpack wing on top tells the story even better:

Wolfpack%20on%20Trumpeter_zps92ozlwzx.jp

Here are the Trumpeter (starboard) and Wolfpack fuselages together. Both have a similar tailpipe piece.

T-38fusecomparison_zps131f59d2.jpg

Back to the wings, I haven't done a really careful comparison of wheel well location, but what I have observed so far is that they're all pretty similar. I do intend to take a closer look at the gear...

Hope this was interesting to some of you, and if I brought any uncomfortable "facts" to light, I apologize!

bob

Edited by gingerbob

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Sounds like there's a lot of confusion on this aircraft, strange as it should be well known. Having 3 different lengths quoted does not help

Regarding those drawings, are they from the D&S book ? If so I wouldn't trust them at all...

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The drawing in the wing comparisons, and a number of others, came from the "Warbird Tech" book. I believe that they originate with Northrop. I also found F-5A and T-38 drawings in a Northrop technical paper, and F-5E and F-5F drawings in a NASA paper (about developing the shark nose). EDIT: Also, another T-38 drawing came from a query on Hyperscale- don't know its origin. There are a surprising number of errors, but I've been able to (mostly) figure out some good baseline measurements. The shape is only a guideline (though seems to be quite accurate, from what I can tell) but it is the dimensional data that I'm wrestling with.

I haven't yet fully puzzled out the E/F wing- obviously they basically "grew" it in the center (an additional 8.5" per side, or a total of 17" down the middle), but I need to do the math to figure out how that affects the main gear location, for example (fore/aft). This is further complicated by the 15" stretch of the fuselage. None of this particularly matters to building models, I'm just enjoying trying to understand how the aircraft evolved. I need to make my own basic "trustworthy dimensional points of reference" drawing, or check the relevant points on my scaled-up station drawing.

bob

Edited by gingerbob

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There are 1/72 T-38 drawings in the Daco book on the type, may be worth trying to find this ? I have the book but because of the way it's bound It's not easy to pass the relevant pages on a scanner, I'll give it a try and let you know

Edited by Giorgio N

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If it is just a 3-view it isn't worth the effort, but if it has station numbers and such I wouldn't mind seeing it- a simple photo of the page would be fine, because I just want to read the numbers (so keep the resolution high!)

Yesterday I finally crunched the numbers- I had to dust off my trigonometry and algebra skills- but I was able to solve the problem of the wing. The problem is that inserting a section at the center shifted the wing numbers (longer centerline chord) and meanwhile the fuselage is 15" longer (A to E) in approximately the same place. So it wasn't just a matter of "add 15 to the station number", and they didn't just pull the wing 8.5" outboard along the perpendicular (which I had to calculate anyway)- it shifted slightly. Whew!

bob

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Well nuts, as often happens, things have spun out of control in the last week or so- real world preoccupations, and new distractions too. The deadline is coming over the horizon like a storm-cloud (but less entertaining). I'm not giving up yet, but will need to change tactics if I'm going to get anywhere. That AFV F-5F is whispering sweet nothings at me...

bob

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maybe you are too academic about this multibuild.... still some time left, so.... !energy!

:)

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Well, I do tend toward the academic, I admit. I hate to admit it, but I've also now got a rival- a new kit has captured some of my attention/enthusiasm. I just couldn't help myself... the good news is that in the last 24 hours I've done both spray (can) and brush painting, and glued a number of bits not only together, but into a fuselage! AND all without cutting myself :winkgrin: Still, as much as I love the F-5 family, I owe it to y'all to at least have one to the airframe stage, even if I don't get it "finished".

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