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Old Jun 08, 2005, 09:20 PM
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Build Log
F-16 Build Thread

This is a build thread for my EDF depron F-16 Falcon. I’ll show exactly how I made my own bird, and will share the plans a little later so you can make one too. I’ve attached a few pictures showing the bird as it looks today. But if you were following my original thread you won’t notice anything new. Same story goes for this video, this video, this video, this video, this video, and this even older video. I wish I could show some ROG video, but every attempt to film has been kyboshed by the wind, rain or both.

Update: Here is the link to the plans. And here is a link to an alternate graphic for the exhaust nozzle.
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Last edited by Thomas Nelson; Aug 28, 2008 at 02:19 PM. Reason: Added yet another video.
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Old Jun 08, 2005, 09:29 PM
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Here are the stats:

Scale silhouette with scale-like flight envelope
Easily hand launched with over 220 watts per pound on tap
Thrust-to-weight ratio exceeds one as a belly-flopper, but just under with retracts.
24” wingspan, 36” long
AUW is 20.5 ounces & up depending on pack used.
DS-30 or Minifan 480 Ducted Fan
Thunderpower 2100mah Prolites Lithium Polymer cells (20.5 ounces AUW)
Mega 16-15-2 Brushless Motor
Castle Creations Phoenix 45 Speed Controller (stock timing, no brake)
Berg receiver
Taileron controls (elevon subroutine) with two HS-55 Servos

Optional:
Wattage Retracts - one HS-85 servo for all three units (25-27 ounces AUW)
Nose gear steering with one HS-55 Servo
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Old Jun 08, 2005, 09:29 PM
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There is a little twist to this thread, however, in that Ralph A. D'Amelio (aka DAF) will actually be building his bird along with me as I describe the steps. I anticipate he’ll be chiming in from time to time, offering additional pictures, suggestions as well as asking questions that will be representative of what others will need to know. You know, stuff that I might gloss over because I’m not thinking about how others might interpret my posts. I hope this approach proves useful!
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Old Jun 08, 2005, 09:32 PM
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A couple of other things before I begin:

This is a very easy to fix airplane. And it is a relatively easy to fly airplane. But it is NOT a tough airplane. Please be sure your flying skills – and especially your landing skills - are up to the challenge if you plan to build it.

You’ll need a computer radio since elevon (or V-tail) mixing is required.
Here’s a partial listing of construction materials you’ll need:
A couple of sheets of ¼” and 1/8” depron. Or a couple/three of sheets of fanfold foam
Adhesives including 3M77 Spray (foam safe stuff), Probond Polyurethane glue, Foam Safe CA, Foam Safe Accelerator.
Various kinds of knives, Exacto, box cutter style, etc. The kind with the break-away blades are good, since if your blade is dull your cuts will be ragged.
Some brass tubing, including telescoping sizes.
12 or more Tiny Neodym magnets (Mine are 1/8” diameter x 1/8” long from Lee Valley Hardware)
Sanding blocks, from 60 grit to (say) 200. I also like sponge blocks and 1”dowels wrapped in sandpaper.
24” of 1/8” Carbon Rod for the spar.
All the usual clevises, servo output arms & pushrod material (I use Carbon rod)
You should be comfortable with the idea of scratch building your own plane. Truth be told, even among scratch builds this one is a little weird since you’ll be heat-forming foam. However, if you’ve built one of Jetset44’s birds you’re well on your way to knowing what to expect with mine. But if all you’ve ever built to date are balsa ARF’s, you may want to reconsider starting down the “foam path” with THIS bird. There will definitely be steps where I am assuming the builder’s previous experience will fill in some gaps.

Not sure how to say the next part, but I feel the need to try: this thread is mostly about the airframe, as well as the templates & techniques to build it. The propulsion system was simply a combo I saw others were using to good effect and shamelessly incorporated into my bird. And I am far from qualified to suggest how to install retracts – this is my first ever bird with ‘em. So please understand if I offer vague answers to questions like: “I want to use what I have lying around. I have motor X, battery Y and Z number of servos … will I still have T/W>1, and will it fry my cells or ESC?” The fact is, I’m not comfortable offering suggestions on motor/fan/cell combos that I haven’t tried. And the combo I’m recommending for this plane is Dynamite. Bottom Line: maybe think about asking such questions in threads that are exploring those topics … this is an F-16 build thread. I hope I’m not coming across the wrong way … but I’ve seen many a good thread evolve into nitpicking debates that had little to do with the original theme. I’m really hoping this “build thread” can serve as the sole instruction set for all who might want to give this bird a try.
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Old Jun 08, 2005, 09:39 PM
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I strongly recommend buying a plastic model of the F-16. 1/72 scale is good. I bought a Thunderbirds F-16 for around 15 bux, complete with decals, so I had a GREAT frame of reference.

You should also download THIS file from airwar.ru. It is a 3 view of the F-16, and will help you with the placement of the canopy, ventral fins, rudder etc. I personally recommend blowing it up to full size and placing it on the wall, but this is not strictly necessary.
Finally, have Kinkos print out the plans for you, or tape the tiled version together. (I know – these files are coming!!)
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Old Jun 08, 2005, 09:50 PM
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Note that each piece is numbered. The number refers to the order in which you’ll be making that piece. Please consider cutting the pieces out as you need them, rather than cutting them in advance - reason being there are “grain” considerations, as well as “film” issues (with fanfold, that is) that I’ll be discussing when appropriate.

Again; hold tight for the plans. These are just snippits of a WIP. The final version will be released toward the end of this thread. We all owe many thanks to Mr Boogie for converting my crappy scans into first rate plans. And Esprit440 for contributing the nozzle graphic, which will be part of a decal set I'll share later.

PS - hey Tom ... notice the fonts are all "hollow"!
PPS - the white space on page 2 will have the landing gear bending template and positioning layout - once I get 'em to Mr B!
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Old Jun 08, 2005, 09:51 PM
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A really easy way to transfer plans to depron is to cut the out the plan and v e r y LIGHTLY mist the back with 3M77. Stick it down, cut the depron & immediately peel the plan off. If you use too much 3M77, you’ll ruin the finish of the depron, or worse.
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Old Jun 08, 2005, 09:58 PM
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Ok – time to build!

The reason I’m suggesting the canopy as the starting point is because it is both easy and hard. ‘Hard’ owing to its numerous curves, and yet ‘easy’ because it can be spackled and painted if the “as-finished” shape leaves something to be desired. And if your first attempt crashes and burns, then you haven’t wasted all that much depron. In any event, this part introduces those who are unfamiliar with “forming” foam to this whole process.

Here’s what you need to do:

Before you cut the piece from 1/8" thick depron, first determine the “grain” of the depron. With a little bending of the foam, you will easily be able to feel that depron “likes” to bend in one direction more than the other. Not sure if it's technically correct to link this property with the term "grain", but that's what I plan to call it from this point forward. With this part, you need to orientate the grain such that it accommodates the rolled “bubble” shape of the canopy. Once you’ve established the orientation of the grain, cut out the canopy.

Next, fill your sink with HOT water, put on some thick rubber gloves, immerse the part and roll it into a tube-like shape. You may find it useful to roll the piece around a (say) 1” dowel, although this is not strictly necessary with this part. (Later on in the build, however, you will definitely want to have some “tools” having a diameter of approximately 1” for the forming process. Something like a shower rod or clothes closet hangar rod).

Basically, the process involves manually forming the piece with your fingers under hot water, then removing it to cool for 10 seconds or so. Once satisfied that the piece is sufficiently round, apply foam-safe CA and close each of the slits. I just hold each slit closed until it cures … no need for tape. At this point you'll have noted that if you cut each slit at a slight angle you will have an easier time closing them.

When completed, you’ll want to paint the canopy flat black (or whatever color you like for your canopy), or perhaps you’ll want to spackle it first. Kinda depends on how well your forming process turned out.
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Old Jun 08, 2005, 10:16 PM
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Next up is the inlet duct. Here's the basic idea:

1. Choose your foam. My preference for this is fanfold, since it is cheaper than depron. The duct will ultimately be made of a composite material, either fiberglass or carbon cloth or Kevlar (or whatever) so part #2 is really only a plug, and will be totally destroyed in creating the composite part. Hence this is called the "lost mold" technique, and is why I'd recommend the cheaper fanfold.

2. Once you have chosen your material, determine which way it likes to bend. You want the grain to allow this part - essentially a big rectangle - to easily form into a long skinny tube. Now cut out your part.

3. At this point, you want to remove the film (assuming fanfold) from what will become the inside of the tube. Do not remove the film from the outside of the tube.

4. Now fill your tub with HOT water, put on thick rubber gloves and roll the rectangle into a tube. Precision is nice, but not necessary. Be patient with the forming process, go in stages. If you rush the outer film will split, and the foam may crack. I like to take the the steel hangar tube in my closet (about 1" diameter and 3' long) and use it as a sort of mandrel (am I using the term correctly?) around which I bend the foam. I push the tube down (underwater) against the foam and pull the edge of the foam sheet up and around the mandrel with my fingers. You'll need to form it somewhat tighter than your ultimate goal, 'cause the foam will relax a bit after you remove it from the water.

5. Once reasonably round, and reasonably close to the diameter needed, remove it from the water and let it dry.

6. Use Probond and glue the joint closed. I wet one side of the foam with my finger, apply the glue to the other, and tape the joint closed. I like to use fiber tape for this since it does not stretch. I find I can achieve a VERY tight joint this way. Also, the tape prevents the Probond from expanding to the exposed side ... all the foaming action stays on the inside.

7. Don't worry if the finished part doesn't look perfect. Being a plug, you can shape it & fix it with spackle later on. However, this is all good practice since you'll be forming the upper fuse shell in much the same fashion a little later. You'll want a nice joint in that very visible part.

Don't remove the film just yet. There's more to do.
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Old Jun 08, 2005, 10:27 PM
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Next form part 3 - the thrust tube - the same way. Note that the OD of both the duct and thrust tube match the ID of the Minifan.

Remove the film from the OD when the Probond has cured.
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Old Jun 08, 2005, 10:37 PM
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Now go back to the inlet duct. You need to form it into the shape pictured below.

Each of these pictures shows two ducts. The unfinished (blue) duct is obviously more "banana-like" than the finished (fiberglas) duct. This is because the unfinished duct is designed to bend around retracts. If retracts are not in your plans (and I'd recommend against them) then you do not need to be so aggressive with the tube.
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Old Jun 08, 2005, 10:48 PM
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Now you need to shape the F-16's distinctive mouth. You haven't removed the film yet, right? You'll need to re-heat the piece underwater and gently squeeze the shape you're after. Use the airwar.ru file (linked above) as your reference. Remember that the outside of the shape you are forming will eventually become the INSIDE of the duct; so be sure to bend those outside corners SHARP. And be careful that you don't split the film.

But let's say you can see that the film IS starting to split. Don't worry, all you need to do is apply some of the fiber reinforced tape to the problem area. Just do this before it splits wide open, or you'll need to spackle the crack later on. Again, even if the "worst" happens, just chalk it up to a learning experience, since this piece CAN be spackled without creating unsightly results. Later on, you'll be glad you had the practice.
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Old Jun 08, 2005, 11:06 PM
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Once you've formed the mouth, it's time to bend the inlet tube. By using fanfold/depron, we can get a relatively smooth transition from the inlet to the MiniFan with a minimum of fuss. But it isn't without some fuss. A couple of points:
Even if you are only planning a belly lander, you'll need to bend the tube some. The fact is, the inlet is below the thrust line, so even if you aren't bending around the landing gear, you'll want to arc it until it exits the bird with neither up nor down thrust.

But if you are planning gear, you'll have to bend the tube around the location in the belly where it will stow. This calls for some fairly serious bending ... and patience.
In either case, you'll need to heat the tube again, and slowly start bending it. You will notice that your efforts are causing the tube to flatten in the area where the gear will go. Further, you will get a sense that the upper surface of the tube is attempting to stretch a bit, whereas the lower surface is attemptig to compress a bit. All three things must occur if the tube is to snake around the gear location. Bear in mind, though, that the more the tube collapses, the more it deviates from area ruling, and the less efficient it becomes. In otherwords, don't go hog wild with the bending.

The pictures below show the crucial measurements you are aiming for. Might seem like this is "loosey goosey", and it is. "Tain't Rocket Science" I'm afraid.

BTW, the reason why the duct appears white in the pictures below is that it has econocote on it. Don't worry - you didn't miss a step. I just didn't take the appropriate pictures at the appropriate time.
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Old Jun 08, 2005, 11:17 PM
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Once you have the a tube that looks like the ones in the preceeding pictures, it's time to peel the film off.

Next, glue the fanfold thrust tube plug to the back of the ducting. You'll cut this off later.

Odds are, you'll need to apply a bit of spackle to fix dings, dents or other irregularities. Remember, the exterior of the fanfold tube will become the interior of your duct, which should be nice and smooth so as not to turbulate the airflow.

Anyway, once you have the shape pictured, apply low heat film to the exterior of the tube. I used Econocote, but anything will suffice. The purpose is to produce a nice smooth surface at the inside of the duct.
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Old Jun 08, 2005, 11:36 PM
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At this point, I made a mistake. I did NOT apply any kind of release agent to the econocote. Result? the epoxy stuck to the econocote, and was a proverbial pain in the donkey to remove. Next time I will use car wax, or Future floor wax etc to prevent the epoxy from sticking to the econocote.

Anyway, now it's time to apply fiberglass or carbon tissue or carbon cloth etc over the econocote. How much you ask? Well the answer is 'it depends'.

For sure, a light weight (say, 0.75 oz) layer should go directly on top of the econocote. Then, perhaps 2 four ounce layers. Then apply your epoxy. Later on, you'll test the result; you may end up adding more glass later, and you will probably end up adding hoops of carbon laminate too.

If this seems strange, it's because I use uber light mists of 3M77 to adhere each layer to the previous. Consequently, I apply all the layers of glass first, THEN the epoxy. Works for me. Others might want to apply epoxy to each layer as they go. Potayto potahto.

Regardless, go EASY on the epoxy. Be sure to scrape ALL excess off. And DO use laminating epoxy, not the stuff that the hardware store sells!

Once cured, it's time to dissolve the fanfold away. I used gasoline for this. Mega messy, and environmentally ... bad. Make sure you get all the econocote out too. I poured the whole goopy mess into my in my outdoor fire pit and torched it. Everyone loved the hot dogs with the je ne sais quois flavoring.

The final result is pictured. The duct with the black hoops is all reinforced and ready to go. The other is fresh out of the gasoline bath, awaiting the "squeeze test" to see where & what kind of extra reinforcement is needed.

Are we done yet?
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