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Old Feb 26, 2012, 05:39 PM
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Joined Mar 2011
83 Posts
Build Log
M64mm EDF F-16

Hey folks,

This is my very first post! Please forgive my newbness on these forums.

I recently bought a pair of 64 mm edf units HobbyKing (as well as motors) with plans to build and Avro Arrow:

HK2836 EDF Outrunner 3800kv for 64mm
Kv (rpm/v) 3800
Weight (g) 97
Max Current (A) 35
Resistance (mh) 0
Max Voltage (V) 15
Power(W) 520

EDF Ducted Fan Unit 7Blade 2.5inch 64mm
Blade Diameter: 64mm / 2.5inch
Blade Type: 7
Shaft Size: 3mm
Recomended Motor: 24-45 6Turn (11.1~14.8v)
ESC: 25A
Rpm: 3,750kv
Power: 400~1500g Thrust
This fan will take up to a 28mm diameter motor.

I gave up on the idea of building an Arrow since it's designed to be an interceptor (really fast, less maneuverable) rather than nimble and maneuverable like a fighter. I only have a smallish field to fly here, so I decided to design and build a small fighter jet first to suit my field. I also don't know any other pilots locally, so I'm also hoping to get some advice from seasoned designers and builders here, basically looking for some peer review.

The F-35 was a obvious first choice for a single engine platform to model and I'm a huge fan of the F-22, but I decided to model a scale-ish multi-role 5th generation Jet fighter, the F-16, instead (incl. flaperons, leading edge slats and retracts).

I'm going to generate some 2D plans before I start actually building, so I'm likely to make these available at some point. I've been doing a bit of research to begin my design, here are a few of my resources:

rcgroups.com - F-16 bulkheads
rcgroups.com - build log - pusher prop conversion to EDF
rcgroups.com - Tim H.'s EDF design
rcgroups.com - Yellow F-16C build log
rcgroups.com - A review of Available F-16 builds

I've been sketching out my design in Blender first since I'm proficient enough with that 3D modelling tool and I will move that design over to 2D ACAD .dwg format (scaled for a 64 mm fan) before I begin building. I'll post a few screen shots of my blender sketched out design shortly.
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Old Feb 26, 2012, 06:31 PM
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Joined Mar 2011
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Low-poly surface mesh

Here are some views of the low-poly surface mesh I created from a 3-view of an F-16. I'm using it to help me sketch out an airframe design with.

I'm also using a 1/72th scale plastic f-16 model for reference, which I built without painting just to get geometry info. (30$)

I'm not going to be building scale wings (too thin). I'll be maintaining the chord lengths, but employing a thickened semi-symmetric airfoil (haven't decided on the airfoil yet), the plan is to keep a scale look.
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Last edited by arrowking; Feb 26, 2012 at 06:43 PM.
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Old Feb 26, 2012, 06:57 PM
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Joined Mar 2011
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Bulkheads and load bearing members

Here are some of my 3D sketches for the bulk heads and load bearing members. I've sketched it out thinking of building it out of balsa and plywood, but I'm also considering making the bulkheads out of 6mm foam with balsa sheeting. I'm also planing for detacheable wings. None of the thicknesses or member sizes are accurate, this is simply a rough sketch.

I'd love comments and criticisms and questions, just remember that this is a work in progress and I'm not done sketching out my plan. I'm going to figure out how to mount the retracts next I think. I'll post details on those shortly.

This sketch shows a straight duct exit of 64 mm. Not shown is a conical section in the tail pipe. I have to figure out how I'm going to pick the intake and exit areas. I'm afraid the intake on this current sketch is too small and might choke the flow. I don't have much ducted fan experience. I can still scale up the entire airframe, however, I'd just be fighting weight and drag if I did that, must be an optimal airframe size for this motor. Something I'm gonna look into.

This might have been better posted in the scratchbuilt edf forum.
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Last edited by arrowking; Feb 26, 2012 at 07:41 PM.
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Old Mar 04, 2012, 06:21 AM
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jocker edf55's Avatar
Nederland, FL, Almere
Joined Jul 2011
102 Posts
nice man, like to see the plans and your progress, i have a complete 64 edf setup for a while now, i like to build this one with it!!

keep it up, drawings looking good!
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Old Mar 12, 2012, 10:55 PM
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Thanks for the comments Jocker, hopefully I'll have some plans available soon.

I'm done with most of the 3D sketching process, Blender was a great tool to visualize some of the design ideas I wasn't sure about. I'm still pulling dimensions off the sketch though.

I'm currently working on modelling the airframe in ALibre, a 3D parametric modeling and 2D drafting software. I'll post some pics up of my progress in a bit.

The design is currently a little over 1 m long. I'm a little afraid this is too large for my particular fan unless I keep the model to under 1 kg. When I look at other 64 mm jets out there on youTube, some of them are TINY! My fan does have 7 blades so I'm sure it's got a bit more thrust than some others out there. Hobby King says the fan can deliver a max of 1.5 kg of thrust on 4s, but I'm a little skeptical. I'll be running a few tests to better determine the performance, I might detail that here. I had to keep the design large as I wanted to be able to mount retracts, but I'm not 100% sure that's very easy to do on a 64 mm F-16. We'll see, I'm continuing to proceed forward with a 64 mm fan in mind and aiming for a super light airframe (foam bulkheads, balsa skin, and plywood/carbon fiber for load bearing members?). Gotta love a challenge.

There's a bit of extra room in the fuselage for a larger fan at the current size, so I could potentially go up to a 90 mm if I find the airframe is too large/heavy for a 64 mm fan. I could also scale down the airframe a bit. I've got plenty of options. I'll keep you posted.

RCPowers - 64 mm F-16 (almost 1 m)
Starmax RC F-16 90 mm Assembling (huge)
Starmax F-16 64 mm unboxing (almost 1 m)
Banana Hobby 64 mm F-16 (almost 1 m)
FMS mini F-16 64 mm (tiny)
G&C 64 mm F-16 (tiny)
TMF F16 64 mm (almost 1 m and insanely fast)
NitroPlanes 70 mm F16 (1 m and a bit?)

RCGroups - geebros HET 90 mm F-16 build log
RCGroups - AceMigKiller HET 90 mm F-16 build log
(These 90 mm F-16s are larger than what I'm aiming for (1.5m) so at this stage, that's reassuring)
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Last edited by arrowking; Mar 12, 2012 at 11:53 PM.
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Old Mar 15, 2012, 02:06 AM
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United States, MI, Wixom
Joined Sep 2007
1,593 Posts
If you want a challenge make it a composite. Sometimes if a jet is too light it ends up being a floater, and has a less than scale flight appearance. Course you can always add battery. !Cool idea for a project. bump
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Old Mar 30, 2012, 11:29 AM
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Just posting some CAD work progress. My main goal is to build and fly this thing of course, but I also want to see if I can generate some decent plans/dwgs that others can follow.

I'm going to be building that right wing shortly to check for strength and iron out some of the details.

I ended up using this guy's bulkheads which I've modified to suit my needs. I also found and fixed a few small issues with them (anyone who lays them out in 3D will notice them right away).

I'm planning on making the intake duct out of fiberglass, and the exhaust duct out balsa sheeting. Any comments on this idea? Note that the exit duct is perfectly straight at the moment, I'm planning on reducing the diameter to the fan area shortly after the fan and a smooth taper to 85-90% fan area at the exist. I know this will increase the thrust, I'm just worried about how the ducting affects power draw and efficiency. I picked 85-90% as I read somewhere this is a good ratio. What are people's thoughts on this?

Anyways, I welcome comments and criticisms, however be gentle, there is still a lot of work left to do on the CAD dwg.
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Last edited by arrowking; Mar 30, 2012 at 11:35 AM.
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Old Apr 13, 2012, 11:13 AM
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So, I've built one of the wings to make sure the wing size was feasible, and it looks pretty good. I haven't built the leading edge slat or the flaperon yet, but I will before I continue on with the design so I can iron out hinging and whatnot.

The wing is quite light and has quite a bit of stiffness due to the carbon fibre "spars" that run partway. I'm using 1/16" plywood for the structural member that run the length of the wing which adds quite a bit of rigidity, but I may bulk that up a bit, I'm not sure yet. It depend on how it turns out once sheeted. I'm also weighing the option of glassing the wing to add stiffness, but that just adds more complexity to the build process, not to mention weight. Thoughts?

I've noticed I designed the aileron to be square which is not like the actual F-16, I will likely modify this.

Anyways, the wing pictured here is just a test build and will get scraped when I start building the whole thing. Notice I'm halfway through cutting off the nubs on the airfoils. Also I'm probably going to start a new thread in the scratchbuild edf section next time I post... Hopefully I'm not urking off to many people. Pardon me.
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Last edited by arrowking; Apr 13, 2012 at 05:20 PM.
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Old Apr 13, 2012, 12:27 PM
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upland CA
Joined Dec 2004
7,603 Posts
Welcome to RCG...looks like some nice work.
scott
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Old Apr 13, 2012, 05:22 PM
it wasn't me flying that plane
Hover or die's Avatar
United States, NC, Wilmington
Joined Mar 2011
723 Posts
Great design drawings Arrowking!!
I had planned to do the F-16 but found the drawing of the F-22 by Nem3 and had to start that one for now..The F-16 is just a timeless jet and it will still look good in the future like some of the others..
Your work on the designs should yeild a really nice model..If I didn't have so many Viperjets going I would jump on board...
Keep the pics coming...
Also,are you OK with sharing the drawings (you have posted)here with members to put together their own model ...?
Thanks..
Take care and welcome to the RCgroup!!!
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Old Apr 13, 2012, 11:58 PM
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Yes, I'll be sharing these dwgs though with some terms applied which I haven't decided on yet.

I may end up only releasing pdfs, but I might end up releasing the ALibre files too and tack on some kind of copyleft license to allow people to more easily modify my design, I'm not sure exactly what I'll do yet. I've got a bit of work to do before I release anything though...
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Old Apr 14, 2012, 12:10 AM
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These are the retracts I'm planning to use:

Turnigy Retract System for 70mm EDF Jets with Fuselage Mounted Undercarriage (F-16, F-18, etc)

Nose Wheel: 30mm
Nose Strut: 74mm
Main Wheel: 40mm
Main Strut: 90mm
System weight: 179g
AUW Load: 2.6kg
Voltage: 4.8~6.0v
Current draw: 0.32A for 2 sec

Wheels are kinda small...
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Old Apr 14, 2012, 12:31 AM
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United States, NM, Farmington
Joined Jun 2008
840 Posts
It sounds like you are already figuring out that a 64mm fan will be too small for the plane you are building. With all the features you are wanting to put on this plane it adds up to weight. With a 70mm fan and the right power combo you should be able to make a 1 meter F-16 fly well, even if the wing loading is high. The thing you should be doing from the get go is designing your plane around the duct sizing, the inlets and exhaust in reference to the FSA(fan swept area). The popular thinking atm is 90% on the intake and 85% on the exhaust.

If you haven't made a thread in the scratch built forum yet(i haven't seen it), you can ask to have this thread moved. You will get much more attention from seasoned scratch builders in there.

The reading you are doing on the other threads will help tons.
Keep up the good work, looking forward to your progress.
C.
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Old Apr 14, 2012, 12:08 PM
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Thanks Corelli, I really appreciate the tips. I have sized the plane around the 64 mm fan, which the duct size is dependent on. However right now, I had a slightly larger intake than FSA. 90% intake - 85% exhaust, I might be able to reduce the airframe size and still fit the front nose gear at the inlet.

I'll get an estimate weight, cg and wing loading. Keep you posted.

I also have the idea of designing the "tail pipe" end and wings as modular. Then I or someone could later design/build/install F-16 XL wings or add thrust vectoring. I have no plans of doing that myself, I'm just thinking ahead. F-16 XL would definitely drop the wing loading.

How do ask to have a thread moved?
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Last edited by arrowking; Apr 14, 2012 at 12:13 PM.
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Old Apr 14, 2012, 12:17 PM
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United States, NM, Farmington
Joined Jun 2008
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I would edit the first post and ask to have it moved to scratch built forum.
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