F/A-18 E Super Hornet SUPERSIZED 150%

[HilldaFlyer]

Leading Edge Dogtooth

No F/A-18 Super Hornet would be complete without the distinctive wing tip dogtooth edge. Since the leading edge of the wings were used to join the upper and lower wing panels together, we’ll have to just add the leading edge dogtooth as an afterthought. In future plans, I may follow the lead of others by making the bottom wing panel shorter and just cutting the dogtooth into the upper wing panel. But for now, this is what I did.

Score cut a piece of foam and fold it onto itself. Bevel cut the edges along the both sides of the fold. I like resting the foam against the edge of my build table and sliding the blade’s handle along the top of the table to stabilize it while running it through the foam.

Like cutting the spar, while it is doubled onto itself, cut a 1.5 cm strip pushing your knife through both layers of foam.

The end result is a strip of foam 3 cm wide with a “V” notch in the middle when it is laid flat.

With the notch facing the build table, bevel cut the outside edges. Because the foam strip is so thin, I use a ruler to put a little more distance between my fingers and the blade.

Angle cut both tips and then bevel cut the outside edges.

When glued they form a concave “V” on the rear to fit around the wing’s leading edge and a convex “V” on the front that can be sanded to a rounded point.

Glue them as parallel as you can with the bottom panel of the wing.

To get the dog tooth’s parallel to the bottom wing panel, I use a scrap piece of foam as a guide to extend the bottom wing panel.

Glue in place with the tip being flush with the wing tip.

 

[HilldaFlyer]

Wing Tip Weapon Rail

The position of the wing tip rail is a little precarious, especially for those of us who fly and land on grass fields. A little foam rail is just too flimsy to withstand even the slightest bump, so I beefed it up with a little balsa. Even so, I expect that the wing tip rail will break sooner or later so I didn’t want to hard mount it (i.e. glue it to the wing tip). So, I devised a system for removal so that it can be easily replaced after breaking.

First, if the wing tip isn’t flat, use a sanding block to make it so.

I cut out a wing tip cap out of card stock. Before gluing it on, however, if you want the ability to secure the rail with a magnet or a twist tie, those need to be attached before you glue it to the plane. Glue or tape the twist tie to the inside of the wing tip cover and then glue the tip cover in place.

The rail is made with a little strip of foam and balsa on the outside.

Toothpicks are pressed and glue into the foam.

Pressed into the wing.

There - a non-permanent wing tip rail. The rail can be tacked on with hot glue or twist tie. I have used a drop of hot glue

 

[HilldaFlyer]

Under Wing Hard Mounts

The F/A-18 Super Hornet is equipped with a wing tip, 3 mid-wing and one fuselage hardpoints for weapon or fuel drop tank attachment. Although adding these is totally optional, it sure looks cool. Because I have a high suspicion that adding mock weapons to the plane will severely decrease flight performance, I wanted them to be removable (not in-flight droppable- rats). To make the hard points, I just used a scrap foam and cut it to a shape in the plans or make your own design. To make all the hard points interchangeable to other spots on the wing, I made a little jig out of foam and a couple of toothpicks. Align and poke holes in the mount and glue in 2 to 3 cm long toothpicks.
Poke holes in the wing at 16, 24, 32 cm from the wing tip. I used a magnet to hold the weapons to the plane and a group of 5 staples in the hardmount. Now they pop on and off. Now you can glue whatever type of pseudo weapons you want.

Here I show how the hardpoints are attached to the underside of the wing.

 

[Blackbeltrrf]

This is looking really great!

 

[HilldaFlyer]

Weapons

I have spent a few nights now just playing around with tubes, straws, ball point pens etc. to get an assortment of what may be called pseudo weapons.

I think they are coming along fine... That's where it is now. I'm waiting for a warm day so I can paint. That may not happen for a while. Cheers from the Northeast.

 

[HilldaFlyer]

This is looking really great!

Thanks...

 

[Troop 17 Aviation Group]

Awesome! Setting aside some supplies to begin building one myself. What's the airframe weight? Would an NTM Prop Drive 28-26 1200kV motor on a 3S LiPo work well? Can't wait for the maiden!

 

[HilldaFlyer]

Powertrain

Awesome! Setting aside some supplies to begin building one myself. What's the airframe weight? Would an NTM Prop Drive 28-26 1200kV motor on a 3S LiPo work well? Can't wait for the maiden!

I'm glad you're going to try... I can't wait for the maiden either and I'd like to see yours!

Weight without battery: 1 lb 8.5 oz. The 2200 mAh battery is 7 oz putting the flight weight at 1 lb 15.5 oz.

I haven't tried the configuration you suggest. My first inclination is that a 28-26 will not have enough power to really fly it well. My other F/A-18 Super Hornet from Dave Powers plans is of similar size (1 lb 11 oz without battery) and I used this:
Motor - GH Super Mega Jet V2 2200 kv (Grayson Hobbies)
Propeller - APC 7x6 (Radical RC)
ESC - Turnigy Plush 60A (Hobbyking)

The reason I would stick to 2200 kv is because the propeller slot (as designed) is 7" wide. A lower kv motor, like the one you are suggesting, would use a longer propeller, like a 9x6. If the propeller gets longer than 7 inches, the slot will cut the outer side walls of the engine nacelles and those nacelles are what give the plan/fuselage strength from front to rear. I'd be afraid that without carbon fiber or other sparing going from the fuselage area to the tail, the tail would just fold when torqued up hard.

I'm going to use the same configuration as above only replace the GH Super Mega Jet with NTM 28-36 2200 kv. Another alternative is to use the lower kv motor and use a 3 blade propeller.
-David

 

[Troop 17 Aviation Group]

Looks like I might be getting a new motor then . I'll post pics as soon as it's ready. Awesome design!

 

[Troop 17 Aviation Group]

So, just a quick motor question: Which is more important, thrust or kV? I would think thrust but I keep hearing people talk kV instead.

 

[HilldaFlyer]

So, just a quick motor question: Which is more important, thrust or kV? I would think thrust but I keep hearing people talk kV instead.

A not-so-quick answer. It has been a long time since I cracked my physics book, so I won't get too technical.

From what I understand about motors and thrust, those two properties are not mutually exclusive... but they are related, kv is translated to thrust with a propeller.

Thrust is how much push the motor/propeller produces (force) and kv is how fast (RPM) the motor tries to turn given a voltage. A low kv motor with a big propeller can produce the same thrust as a high kv motor spinning a smaller propeller faster. The larger propeller will be more efficient (produces more thrust per watt input - see last paragraph).

In the situation with this plane's design, the plane will support a maximum of a 7" propeller. Then the question then becomes, what motor do we need that will spin a 7" propeller and produce the thrust needed to fly? If the prop slot was larger, I probably would have gone to a lower kv (say 1400 or 1200) and put a bigger propeller on it...

The motor you suggested NTM 28-26 1200 kv (according to my bench test) produces 26 oz of thrust with a 9x6 propeller. If you put on a 9x4.5 propeller, their is a small uptick in thrust to 28 oz but also increases the amp draw (from 16 to 17.5). So this combination would probably fly this plane, but I think you would feel very unsatisfied because the thrust to weight ratio is below 1 (the flight weight is 32 oz). Additionally, you would have to cut the prop slot 1" wider on each side. The engine nacelles could be widened also, but then the fuselage would start looking like the FT-22 (not-so-scale) flat and wide. In reality, the nacelles were widened past scale to accommodate a 7" prop. It should have been a 6.5" prop max, but since I'm designing it, I decided on 7".

The NTM 28-36 2200 kv produces 40 oz of thrust with a 7x4 propeller (I used 7x6 with the Grayson Hobby motor earlier). This combo at max throttle burns 40 amps. The 7x6 prop produces 38 oz thrust at 49 amps which is kinda pushing the motor's limits (but it would be faster). With the 7x6, I wouldn't run it full throttle all the time. To be safe - I'm going with the 7x4.

Just for reference on efficiency, the 28-36 1400kv (same size motor but lower kv) produces the same thrust (40oz) with a 9x4.5 prop at 28 amp. This is 10 amp less than the same size higher kv setup.

 

[HilldaFlyer]

Paint Color?

I'm trying to decide on a paint color. Let me know if what you want..

I love the Blue Angels scheme - if you haven't noticed from my other builds... but it is fantasy since the Blue Angels fly F/A-18 C Hornet and not the F/A-18 E Super Hornet (as I've built). Hmmm.

I also have never seen the Blue Angels paint scheme with armament attached. I've made a lot of missiles out of ball point pen shafts ad painted them grey. To make an armed one look real, I was leaning towards the grey. I don't know how visible it is against the sky, trees, grass etc.

As I'm typing, why not paint the missiles blue and yellow and really make a fantasy craft?

 

[Troop 17 Aviation Group]

Thanks for the feedback! I honestly do not have money lying around for a new motor/ ESC at this point as I am about to go off to college. I really like the scale look of the F-18E that you designed (expecially the nacelles and weapon racks). I think I may try something similar with an F-14D design and see if I can fit my motor combo either prop and slot or tail mounted. Now that I think about it could I do a tail mounted motor on your design?

For your F-18E I would go with the gray USN paint scheme with some black trim, but that's just me (I prefer a more rough and grimy look to military aircraft). You are obviously a Blue Angel guy though so I think you will be happier with the blue and gold paint scheme. Heck, you could probably get a tube smoke and some model rocket igniters and work out a smoke show (just don't catch anything on fire ) I will keep you posted on my build if you'd like.

 

[HilldaFlyer]

Thanks for the feedback! I honestly do not have money lying around for a new motor/ ESC at this point as I am about to go off to college. I really like the scale look of the F-18E that you designed (expecially the nacelles and weapon racks). I think I may try something similar with an F-14D design and see if I can fit my motor combo either prop and slot or tail mounted. Now that I think about it could I do a tail mounted motor on your design?

True, you could definitely do a tail mounted motor. You'll have to rework the tail. If you're going that route, I'd probably make the whole tail one long elevator and mount the motor to the moving control surface for vector thrust. That would reduce the need for two servos in the back. The battery would have to be mounted way in the front, perhaps very near the nose.

The F-14 is more tailored for a rear motor mount because the elevons are flush with engine nozzles. The F-18 has more of a "V" shape that would be hassle. If you want an F-18... your motor will work great on the regular size one... mounted on the tail.

Let me know how it goes... Best in college.

 

[Troop 17 Aviation Group]

Thanks, any considerations on the paint scheme?

 

[Flyingninja]

I think something like this:

 

[HilldaFlyer]

Military grey... sort of bland
How about a CAG Paint

Now we're talkin'

 

[Troop 17 Aviation Group]

Love the CAG scheme, had a chance for a maiden yet?

 

[HilldaFlyer]

Love the CAG scheme, had a chance for a maiden yet?

No... weather is not very cooperative. Still dark after work and this past Sat. was raining.

Here is what I'm thinking... but at first it looks a little too much like the Blue Angels... so I may do the black and red

 

[RCman50]

Great work David, as usual. I have a quick question. Do you know of an easy way of removing paper from Ross FB. I love the stuff, much better than dtfb, but as of now i am using a rattle can of white spray paint applied to the board and the paper comes off easier. (found this out by accident) Do you know of an easier way? By the way you are one of the main people that got me to to start messing around with glassing FB. It makes for such a better model once you have perfected the build techniques. Thank you for all you do for the community, Dustin