I finished up a build of the new RC Powers F-18 V5 a couple weeks ago and since then have accumulated about 40 flights on this new plane.
One of the first things that attracted me to the F-18 V5 is it's size. With a 27.5"/70 cm wingspan, I knew it fit right in with the size of park jet I prefer. All previous versions of the RC Powers F-18 have been quite larger with wingspans varying from 30" (V3) to 36.5" (V2). The V5 is 37"/94 cm long. It seems to be based very closely on the original F/A-18, so from a scale standpoint it is about 1.5" shorter than scale, but still is a very good interpretation of the F-18 in my opinion anyway :)
Other than using paperless Dollar Tree foam (DTF) for the KF4 airfoils, I used Fli-Power Value XPS foam from RC Foam (an MPF Grade B equivalent) for this build. I used 4mm carbon rod for the wing reinforcements in place of the 3mm carbon tube recommended as I knew I was going to be a bit above the 19 oz/540 gr weight recommendation. Also, from previous V5 builds of MPF foam, I knew this would give me a very strong wing. I reinforced the back plate with some 3mm carbon tube and the vertical stabilizers with the same. The elevons are quite small, so I didn't reinforce those at all.
I am using the DYS 2208/7 2600 Kv motor (a "medium" choice from our Recommended parts list), a Master Airscrew 6x4x3 prop, Turnigy Plush 40A ESC and 2200 3S battery. For controls, I have elevons, ailerons and rudders. To keep things light and to continue an experiment I have tried with a previous plane, I am using RC Timer 9 gr nylon gear servos for the elevons and RC Timer 5 gr nylon gear servos for the ailerons and rudders. By using these 5 gr servos on the small ailerons and rudders, I saved 24 gr/0.85 oz and thus far they are working very well.
- I lowered the battery tray down about 1/2" over the plans to help with better vertical balance and hopefully have some of the "self righting" tendencies that I like so much from the F-18 V3;
- I used KF4 airfoils, sized to what works for me. On the plans, they recommend KF2 and they looked quite small to me. I used 40% of wing chord at the wing root and 35% at the wing tip;
- I placed all the servos ahead of the prop slot to concentrate as much weight as possible around the CG;
- I did not use the foam spacers for the motor mount as I have found these to be a constant source of failure on the V5 series of planes.
My AUW ended up at 20.2 oz/573 gr with a 2200 3S battery. Like the other V5s, the F-18 V5 has a very lower parts count is a very straight forward build, structurally strong and looks scale.
In the picture on the left below, you can see that because I did not use the foam spacer, I had to trim about 3/8" off the back of the nacelle to ensure good prop clearance. It did not affect the structural strength at all.
In the picture on the right, you can see my servo layout. The pin is indicating my CG after flying and dialing it in. From left to right, my rudder, elevon and aileron servos.
My CG ended up being 1/2" ahead of dead center on the "CG spectrum" that RC Powers uses on their V5 planes. My PMI (distance from the front of a 2200 3S battery to the back of the bullet nut on the motor) is 10", so very tight and compact around the CG.
All measurements are one way, pictures of where I held the ruler to make the measurements are below.
Elevons - 3/4" in the pitch, 1" in the roll;
Ailerons - 5/8";
Rudders - 5/8"; and
Flaps - 9/16" (more on these later)
Once I got the CG dialed in, the launch is quite docile, I set about 60% throttle and an easy release and it stays stable until I fly it away.
Even with small control surfaces and little control surface deflection, the the F-18 V5 turns effortlessly. Before putting on the "missile rails", I found in the wind I needed some rudder to help it track straight in turns in the wind, now with the missile rails, it seems to track straighter and more true, needing only a little bit of rudder in winds around 15 mph.
Loops and vertical maneuvers
The F-18 V5 is responsive in all three axes, but probably the most responsive in the pitch. It moves very quickly and smoothly into loops, split S, and other vertical maneuvers and floats effortlessly over the top. I found as I crested the top of loops it was best to let off the elevator and let it start to drop the nose naturally while inverted, otherwise my loops ended up almost egg shaped with a very quick transition at the top because of the pitch responsiveness.
Rolls are actually very crisp and axial, even with fairly large angled tails like are on this plane. I did need to crank up the aileron throw a little bit more compared to some of my other planes to ensure the nose stayed tracking straight in the roll axis.
Even with quite small rudders, the F-18 V5 responds very quickly in the yaw axis. With the small amount of throw I have, I can do very slow rudder rolls, but it doesn't snap around and cause the nose to drop aggressively. In stall turns, it is normally very clean and efficient, I rarely needed to add any opposite aileron to keep the wings flat unless I got too aggressive with my rudder input. For slow flight, the rudders work very well, just a tiny bit of deflection is needed to get the nose moving in flat turns while flying slow.
The F-18 V5 has very predictable stall characteristics, perhaps by lowering the battery down somewhat, this modification helps it fall forward almost every time and the good vertical balance actually causes it to slide back slightly before the nose falls through. It is very predictable and easy to recover from a vertical stall.
Slow flight/high alpha
The F-18 V5 is quite stable in slow flight, with the addition of the missile rails, I found I could comfortably fly down to about 30-35% throttle and it stayed quite predictable. Tip stalls when they did come on were normally fairly slow and I could recover from them with a little shot of power and opposite roll input. Without the missile rails, I had to hold about 40% throttle and tip stalls were much more aggressive when they occurred.
Unfortunately, perhaps because of my setup, the F-18 V5 is not a "high alpha machine" like the F-18 V3. I found with or without flaps/spoilers that as soon as I got slow and tried to pull the nose above about 30 degrees AOA (angle of attack), wing rock came on quickly and aggressively. I am not much of a high alpha flyer, so for the improvements in maneuverability and quickness that this plane and my setup provides, I'm happy to make that sacrifice.
This is another area other than the quickness and agility that shows big improvement over all previous RCP F-18s I have flown. Of course having a much shorter wingspan helps, but this is a very speedy plane, even without a big, powerful setup. It is stable at speed, no torque roll, speed wobble, it just buries the nose and gets going in a hurry. It's shorter wingspan and smaller size makes it feel very slippery in the air compared to previous RCP F-18s I have flown.
The F-18 V5 feels very well balanced when gliding power off, approaches to landing are very smooth, it establishes a good natural sink rate and even without flaps, it needs just a tiny bit of elevator to hold it off at the end and touches down very nicely.
I spent quite a bit of time experimenting with flaps (flaperons actually) to see how they affected slow speed flight and shortened the landing approach. I started off at about 3/8" deflection and gradually added more until I was at about 5/8" deflection. At 5/8", I found it became a bit too "mushy", responded very slowly and felt on the verge of stall quite quickly. I backed it off just a touch and found that about 9/16" deflection worked really well for me. I could comfortably fly slowly as mentioned above and it felt stable and forgiving.
Where flaps really made improvement was in the landing approach, I probably reduced my landing approach by about 50% and landings were very slow and soft. I have the flap deployment set up in my transmitter to deploy them slowly, probably about 1.5 seconds from the time I flip the switch until they are deployed. I deployed them up high and they do cause the nose to drop fairly significantly, probably about 30 degrees nose down when full deployed. However, since the plane is so responsive in the pitch, a little up elevator and the plane stayed level. I suppose if I wanted to get fancy, I could mix in some up elevator with the flaps, but I like having to control and fly the plane myself in this situation.
Like most planes with angled vertical tails (in relation to the wing plate), the F-18 V5 does display some "tail wag" in the wind. I have flown this plane regularly in winds from 5-15 mph. I probably wouldn't fly it in wind much stronger than that, the plane might handle it, but for me it isn't much fun. The "missile rails" did smooth out a lot of the smaller "bobbles" through turns in the wind, so that was a big plus. I would say the F-18 V5 is better in the wind than the F-18 V3 as it is not as "draggy" and much more responsive when I needed it to be.
I'm not normally one to add things to my plane for scale looks, but after seeing how well they worked on the NAMC Su-27 Flanker, I decided to give them a try on the F-18 V5. I looked at several pictures to get some measurements for the scale size and proportions and determined they needed to be 6" long. I used a strip of scrap Depron and a strip of paperless Dollar store foam to get the width right and then glued them on after shaping and painting them. Not only do they provide a nice scale accent to the plane, but improve it's wind and slow speed stability.
The F-18 V5 sits quite low to the ground, there is only about 3/8" clearance between the bottom of the nose and the ground when it is sitting still. Since it lands really well, it will slide somewhat on touchdown and the nose will touch the ground as it is sliding. I put a very thin layer of glue (Foam Cure equivalent, but epoxy or even tape would work) on the nacelles and the nose from just forward of where the front of the LERX meet the fuselage. Thus far it has been protecting the foam in these areas very well.
This is a very simple, straight forward build and it flies really, really well. If the F-18 V3 is the "smart plane" of RC Powers F-18s, then I would class the V5 as the "sports car". It is quick, agile, aerobatic and fast. RC Powers classes it as a trainer/aerobatic, I wouldn't necessarily agree with the trainer part, I think it is a bit too responsive for that, but perhaps built with their KF2 and the moment of inertia lengthened by placing servos behind the prop slot might make it a bit more docile. Personally, even though it doesn't do high alpha very well, I am very pleased with how it performs otherwise, it's speed, agility and ease of maneuverability make up for that immensely for how I like my planes to fly :)
Well done, RC Powers :)