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Old Jan 18, 2010, 10:57 PM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
24,698 Posts
Build Log
F-84F Thunderstreak

Well, the Hellcat is done and I've taken a one day break from building so here it the start of the F-84F.
I still don't understand the Air Force's reasoning on the designation. The F Model, swept wing version, came after the G model. Evidently whoever designated the model number didn't know their alphabet.
Anyway, this one will be one of my very typical builds. At 1/8th scale it's a big airplane. 50" swept ws, 64.5" long, about 5 sq ft of WA so almost any weight will fly good. So I won't stress out over weight and I am doing a fiberglass fuse on this one too.
The only major problem I see here is getting the stab secure enough. It sits up in the fin and is an all flying tail. The stabs are swept and they are HUGE! I can see a good chance for flutter here so I will be strengthening that area. I will also be using GGRN's double carbon tube system for the all moving tailplane.
Planned power is a Scorpion 3026-890kv which I'm also using in the T-33A and F-84G. They weigh 6 and 7 lbs respectively and the Scorpion flies them great.
I like to start by making "my" set of plans(templates) and "my" kit. I use an overhead projector to enlarge the 3 views. My plans really only amount to a top view, side view, wing planform, and front view. My kit consists of the wing foam blanks, fuse foam blank, and fin and stabs cut out of 9mm depron. The fin will be two laminated pieces of 9mm.

J
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Old Jan 18, 2010, 11:15 PM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
24,698 Posts
I started by gluing 3 pieces of 3" foam together to make the fuse blank. Then I transferred the template shapes of the top and side view and cut it to shape.
I marked all the center lines on the blank along with the cross sections stations. I used the cross sections to make reverse templates for carving the fuse shape. These I use to constantly check the shaping of the fuse. One pic shows where I shaped just the cross section areas, once they were close I removed the foam in between until I got to the rough shape. I then remarked all the lines on the fuse so I can get it to a final stage of shaping. Once it is done then I will have to spackle to fill all the imperfections.
Other pics show me squaring up the foam blanks for the wing cores. These are ready for the airfoil templates now.
I have to make each wing in two parts because of the length of the swept wing and so it will fit my bow. I have two bows but this will still not fit in even my large bow. I also made a wing middle section that will fit the fuse. Once cut I will glue them together with lite ply braces and glue the beds together so I can skin the wings.
I've also cut out the stabs and fin pieces. The canopy mold will be made as a separate piece.

J
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Old Jan 19, 2010, 01:01 AM
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Duarte, CA
Joined Jun 2008
218 Posts
Looking good J. I'm excited to see the master at work. What type of glue do you typically use to laminate the foam sheets together (3M77)? I'm guessing the adhesive doesn't hang up the burn wire. Also do you use half negative templates and just check the section on each side? Sorry for the multiple questions. I'll be following along with interest.

Ben
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Old Jan 19, 2010, 08:37 AM
michigan jet guy
mrshea's Avatar
USA, MI, Caledonia
Joined Jul 2007
1,101 Posts
this is great j. Isee your building from a three view and had a question. I was going to attempt to design one of these in cad but couldn't find a view with cross sections. Are just guesstimating or have you view with cross sections. If you have answered this question before sorry for asking again. Will be watching very closely. One of my fav's right along with the f-100. Thanks. phil
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Old Jan 19, 2010, 09:14 AM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
24,698 Posts
Thanks Ben,
I have a can of 3M 77 that is about 6 yrs old. I tried to glue the three foam pieces for the fuse together with it and it would not hold. It may be too old like me. So I went with 5 min epoxy. I only got into the epoxy in one place while cutting the blank, just reached over and turned up the voltage to get through it. But now after shaping I have a section on the end that has epoxy sticking out. When I get done shaping I will dig that epoxy out with needle nose pliers and spackle the hole.
And yes, I use half templates and check each side as I go. No problem with the questions, that's what the thread is for.

Hey Phil,
I could not find a 3 view on the net with cross sections. Then I went through my books and found a great one with about 9 cross sections. I copied those on transparency sheets and put them on the projector. I have three books with 3 views of jets, I'll try to post a pick of one later, they are great books.

J
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Old Jan 19, 2010, 09:19 AM
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Ann Arbor, Michigan, United States
Joined Sep 2003
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J- that looks like another awesome start. will she make the trip to vegas this year? maybe you should make while you're at it so that you can fly formation with Hans?
-beanie

ps. J- can you list the names of those 3 books with the cross sections? i'm always looking for a set of good 3-views with cross sections as well.
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Old Jan 19, 2010, 09:29 AM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
24,698 Posts
Thanls beanie,
She'll make SEFF and Vegas. I'll get a pic of those books, they are good ones. They are are a 3 book series, Vol 1-3.

J
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Old Jan 19, 2010, 02:03 PM
Wannabe B-26 pilot!
Matt Halton's Avatar
Southwold, Suffolk, UK.
Joined Nov 2002
4,912 Posts
You're off to a quick start there John-one day off? lol!
I wish I had just a little of your impetus!

I'm all tuned in now
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Old Jan 19, 2010, 03:03 PM
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Crystal River Fl.
Joined Jul 2008
3,681 Posts
Great start John as always! This will be another great one, too, I still think your gona have to get a bigger trailer! I bet this one would look really cool with the retracts too,, seein that nose gear come up and tuck away! wow.. just had to get that in there... well back to the shop, gotta do something today, sunny and 68 finally,, did fly this morning.. need to look at the f16. w.
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Old Jan 19, 2010, 04:14 PM
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Rapid City SD
Joined May 2004
63 Posts
J,
Your first post about the designation of the F-84F has brought a lot of questions from the very beginning.
One of the major limitations of the pre-F model F-84s was power. Although the J35 was an advanced design (one of the first axial-flow), it was not robust in power output (Initially about 4,000lbs of thrust in a 10-20,000lb jet. Later models had upgraded J-35s with 5,600 and 7,000+ with AB, but their GW were well over 20K). Its slim design did allow for a narrower fuselage (than centrifugal-flow.)
The F-84 had a very rough start. Most could be attributed to being in too big of a hurry. The F-84 Bs and Cs were moved into production well before an extensive testing program could ferret out problems. Handling issues and structural failures caused these early examples to be retired very quickly. Only the already in production D model (which has designed in fixes) saved the design from complete cancelation.
Okay F-84 fans let’s not get our hackles up! This was a trying time in aircraft design/development/production. Many of my personal favorites were near basket cases. Whenever huge leaps in technology are involved…you can expect some issues.
The beginning of the F model: The AF wanted to meld the performance of the F-86’s swept wing into the F-84. This led to the YF-96A, basically a swept wing F-84 with the same (but upgraded) J-35 engine. The initial indications from congressional purse holders to a NEW fighter based on the YF-96A was…NO! In their defense, the performance increases were not staggering. The AF then repackaged the proposal as a “low cost” mod to the existing F-84 design (F-84F), quoting a 55% commonality in production tooling. This maneuver sold the design….BUT the AF then decided to re-engine the F model with the J-65 (over 7,000lbs without AB & the jet didn’t weigh much more). This led to a complete re-design of the fuselage as well. The production tooling commonality dipped to 15%. If this weren’t bad enough, the J65 slid its production by 2 years…..directly translating to an equal slide in the F model.
Regardless of the problems the F-84F was a sweet machine. A friend of mine flew P-40s, P-51s, F-84s, F-86s, and B-57s (WWII, Korea, and Vietnam). He told me that if there was any machine he flew that he would feel comfortable turning a newbie loose in, it was the F-86. Not gotchas anywhere in the envelope. The older 84s he flew had multiple gotchas and were under powered. He told stories of flying brand new 84s out of the factory to deliver them to ops units. The runway at the factory was really too short for the 84….but they made due. He said the acceleration upon break release was “underwhelming” to the point of scary slow. You had to trust the computed takeoff data, horse it off at the over-run, and suck-up the gear before the fence. Their inside joke as 84 drivers was “the nose gear will not lift off until it sees the over-run” or “we used to tie a sack of sand in front of the nose gear so that you could fool it (pull the string), so it thought it was in the over-run”. When you factor in the fact that these were the days before 0/0 ejection seats…..the first generation of the jet age had many ways to eat your lunch. His only matchup with an F-model came while flying an 86. In the old days any fighter seeing another would “mix it up” no matter where they were (today you’d lose your wings). He saw an F-84F, opposite direction, low, but thought “I don’t have the time, and he can’t touch me…so I’ll just press on”. The F-84F reversed direction, climbed, accelerated, and caught my friend….zipping by him and waggling his wings…letting him know he’d been had.
WOW…. J, I promise NEVER to reply to one of your posts with this much caffeine in my system. (Uff-Da!)
George
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Old Jan 19, 2010, 06:17 PM
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Canada, AB, Okotoks
Joined Apr 2007
1,296 Posts
John,

When the wing(s) are in the foam blank stage, do you use a hot wire cutter to do the initial shapping, then sand? or am I way off?

deuce
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Old Jan 19, 2010, 10:37 PM
Fast Jets for Fast times
Lmeano_from_MO's Avatar
St. Peters MO.
Joined Nov 2007
1,210 Posts
J,

This is going to be a great build and this era has so much to choose from in manufactures and designs. How do you hide your supply bills from the wife with all these new projects? I have been trying to shift it around with different purchasing places but she got wise when I went to the boat shop and I donít own a boat. Glassing is expensive.
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Old Jan 19, 2010, 10:50 PM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
24,698 Posts
What can I say Matt, it's what I do.

Yeah, yeah, Walt. Retract, smretract. One of these days. And no I don't need a bigger trailer, I just need to pack less planes.

Thanks George,
That's all good material. Appreciate you posting it. I've heard of the 84s rep, but the way I heard it had a "gravel sniffer", wouldn't lift off until it smelled the overrun.

deuce,
The foam blanks are squared up so you can then use airfoli templates to hot wire the airfoil into them. I did that today.
Wade sent me some copper tape used in stained glass making. I've been fighting the alum tape method, scroll saw a template out of 1/8" lite ply and then wrap alum tape over the edge that the wire passes over. It isn't easy to put on and doesn't hold up well to heat. The copper tape is great! I just sanded the templates a little and put the copper tape on. I LOVE this stuff. Got so excited I forgot to run a candle over it to help make the wire slide. Didn't matter, slid like butter. So thanks Wade, you made my day.
Didn't get many pics but it shows the basics.
I use a negative template for the airfoil. You have to make two( top & bottom) but I find them easier to make and use.

beanie,
Here are pics of Vol #3 of the 3 set series of jets. Nice books and I included a pic of a sample of the three view that it has on every plane.

J
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Old Jan 19, 2010, 11:10 PM
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Ann Arbor, Michigan, United States
Joined Sep 2003
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J- thanks for the pics and info on the book. i did a search on amazon and found one volume, but not the rest. then i found it on ebay for way cheaper so i picked up all three volumes. thanks for the tip! i can't wait to leaf thru them and see what else to build.
-beanie
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Old Jan 19, 2010, 11:36 PM
Now in TN!
J Morgan's Avatar
Chapel Hill, TN USA
Joined Apr 2001
24,698 Posts
Quote:
Originally Posted by Lmeano_from_MO View Post
J,

This is going to be a great build and this era has so much to choose from in manufactures and designs. How do you hide your supply bills from the wife with all these new projects? I have been trying to shift it around with different purchasing places but she got wise when I went to the boat shop and I donít own a boat. Glassing is expensive.
HA! I quit long ago trying to hide them. We've been together a LONG time and she supports my hobby. I occasionally take her shopping in Nashville, Franklin, or Brentwood. She catches up rather quickly! Plus it keeps me in the shop and out of her hair.
I cut my own cores most of the time. The long big swept wings with narrow tips are really tricky and tough for one person to do. I recently taught her how to handle one end of the bow(F-84G build) and she caught on real quick.
So I can look forward not to fighting those types from now on.
I chopped this wing up into multiple sections because my large bow isn't long enough for this long swept LE to fit. Plus she is still rehabbing from surgery and I didn't want to bother her with it.
Listen, just explain to your wife that scratchbuilding is a WHOLE lot cheaper than bars and other women.

beanie,
Man, that was fast! Hope you're pleased with the set of books. I really like them. I've used them on several builds, just cut the 3 view out, copy on transparency, and throw it on the overhead projector. I looked all over the net for 3 views of this model but couldn't find any. Then I checked my library and there they were.

J
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