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Feb 21, 2021, 11:37 AM
I know the Inside out.....
Thread OP
New Product

Falcon F5K

I am very happy to announce to the world: the amazing Falcon F5K.

Today I flew it for the first time – it is fantastic!

Nicolay did a tremendous job. The build quality is superb and the weights are incredible: the all up weight came out at an amazing 221 gram with using 2 KST 08 and 2 KST 06 and a 450 mAh 2s battery. That is exactly the same weight as my F3K Falcon, and I can get down to 212 grams if I use a 350 mAh battery!

The best part is how it flies: exactly like the Falcon F3K. Super smooth and responsive, signals thermals very well, circles with ease, and penetrates very good into the wind.

Empty weights:

Wing: 72,4
Fuselage including nose cone: 32,9
Elevator: 5,6
Rudder: 4,3

Set up:

Rudder and elevator: KST 06
Ailerons: KST 08
Motor: F1507 3800 kv
Vladimir 25 mm spinner and prop: 6 x 3
ESC: Hyperflight 25 A BLHELI
Battery: Tattu 2s 450 mAh

Flying weight: 221 grams, (212 grams with a 350 mAh battery)

CG: 62.6 mm
Aileron up: 8.5 mm, down: 9 mm
Elevator up: 9 mm, down: 8 mm
Camber: speed: 0; cruise: 2 mm; thermal: 4.5 mm
Snap flap: max. 4.5 mm – at max. up elevator

The build – see pictures

I attach some photos of this beauty and my build solution below. Nicolay provides a tray for 4 KST 06 and a ballast tubes that sits on top of it. This also ensures an easy installation – see second post.

However, I wanted XT08 for my ailerons and decided for a different build solution:

1. Aileron servos

Two things are very important:

One is that you leave enough room between the aileron horn and the fuselage. If not, you will not be able to fit the wing and get the steel rods in the aileron horns. My aileron horns are 3.3 mm from the edge of aileron. This gives you slightly over 4 mm room to play with. I feel it’s a bit tight, but it works.

The other thing is that you want your carbon outer tubes perfectly aligned such that the steel wire runs freely in the tube. Wire and tube is provided in the kit but I use 2.5 mm outer diameter carbon tube and 1 mm steel wire.

- Drill small holes in the side of the fuselage – just above the seam, and file it bigger to hold the tube

- Take a piece of carbon tube of about 6 cm

- Fit the servos in the tray, connect long pieces of steel wire and slide these in the carbon tube and then slide everything in the fuselage. Your servos disappear completely. The good thing is that you have created a space for the 450 mAh battery. It can sit under the second part of the servo tray!

- Don’t forget the off-set for the servos. Connect your receiver and aileron servos and power everything up so you are sure that your servos are at your desired zero-points. Tape a piece of flat wood underneath the wings to ensure your ailerons are fixed at the zero position. Place the wing on the fuselage and mark the steel wire for where you need to bent it.

- Hold the wire to the fuselage with your thumb and with your other hand and a small plier, bent the wire in one go. Protect the fuselage by putting some layers of paper towel or an old t-shirt between wire and fuselage.

- Cut the excess wire with a big plier using a small piece of 1.7 mm thick wood to leave the right distance. You will never be able to cut the wire that close to the bent. It will leave about 2.7 mm. Now place another piece of wood of 2.6 mm and file the steel wire until it is flat and smooth around the edges. (you might want to do a dry run first to see how it all ends up…)

- In my case, I ended up with perfect aileron rods. Power everything up again and place the wing on the fuselage and connect the aileron rods. Move the servo tray back and forth until your ailerons are at their zero point again. Check your travel distances. Any difference between the two servos can be managed by changing the zero point

- The very last step is to glue the servo tray and carbon tubes.

2. Rudder and elevators servos

The measurements for the servo tray are shown in the photo. I removed the lugs from the X06 servos. The servos are locked in place between the two pieces of balsa. I put some epoxy on the top of the seams. I can replace the XT06 if needed. Just put a hot soldering iron on the epoxy and moments later you can take out the servo.

Make sure you extent the servo wire of the back end servo. The tray with both servos slides easily through the square opening, into the fuselage. Glue it in after you fitted the aileron servos. This way you can make sure that the servos do not run against the carbon rod.

Since the servos sit on top of a 7mm wide balsa beam, there is room on each side to slide in tungsten ballast weights. I made a few ballast rods and I can now fit a total of 54 gram. There is enough space to add another piece of tungsten welding rod of about 10 grams on each side. This would give me 2 x 37 gram and thus a total AUW of about 295 gram.

3. Motor

There is a firewall in the kit, I made my own, it measures 27 mm in diameter.

4. Receiver and Altis

They find a nice spot on the servo tray, on top of the battery. There is room for the Altis Nano, next to the GRX 6 receiver.

5. Balancing

Everything balanced out quite nicely. I definitely wanted to be able to use the 450 mAh for recreational flying and use the 350 mAh for when I need to take the Altis on board during competition. This meant that I needed to glue only 2.3 grams of lead in the very end of the fuselage. I did this before I fitted the rudder.

But this is not required when you only fly with the 350 mAh battery – and I am sure that when you use the advised build method - see next post, you do not need to add any weight ate the very end of the fuselage.

Flying the Falcon F5K

Well, I can be short about this part. I am flying the Falcon for quite a while now and I love it. I didn’t had much time to test out the this F5K version but it felt very much the same as my F3K.

The ‘launch’ by the way, is quite exiting. On 2s I am getting about 70 to 80 degrees climb-angle and I am over 60 meters within seconds.

Happy flying!

Last edited by Rosbrik; Feb 21, 2021 at 12:32 PM.
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Feb 21, 2021, 11:39 AM
I know the Inside out.....
Thread OP
A few words about the build option with 4 KST 06 servos.

Nicolay provides a 3D printed servo tray that holds 4 KST 06 servos. On top of this tray, you can glue an optional ballast tube. Three different weights up to 55 gram or so, complement this set.

The servos tray with the ballast tube on top, slides into the fuselage. You must set up your aileron servos in exact the same manner as I describe in my first post.

Once in place and at the right spot, you can glue two pieces of balsa between the fuselage and the ballast tube - this is on each side of the square opening in the fuselage.

This will keep everything nicely in place. In case you need to replace a servo, you can simply cut the balsa away and slide the whole servo tray and ballast tube out of your fuselage again.

This is at least how we think this build should be approached. My flying buddy will go for this set up and I am sure he will reports pictures of his build later.

Feb 21, 2021, 01:48 PM
in awe of glide...
Kirkerik's Avatar
That is a very light airframe!
I suppose structurally it does not have to be nearly as robust as the f3k version and of course the fin can be smaller too. Although, isn't there a min weight for F5K class??

You might be able to move the tail servos back a bit more, maybe even the aileron servos too reducing need for tail weight. No? Too tight?

Nice build! Enjoy!

Feb 21, 2021, 02:44 PM
I know the Inside out.....
Thread OP

Yes, there is a minimum wingload required. I belief it is 12 gram/ dm2 and so I will need to add weight for competition.

But I did not primarily bought this plane for competition and I wanted the F3K feeling of a light plane that responds well to light thermals.

Indeed, it doesn’t need to be superstrong but you must be carefull with handling this plane. The wing dents more easily than my standard F3K wing.

I think I could have moved the servos a bit backward but I wanted to be able to set up the strings and have access to the servos in case I need to replace them.

And also, I can not complain about 221 gram with a 2s 450 mAh and 212 with a 2s 350 mAh battery....
Last edited by Rosbrik; Feb 21, 2021 at 06:32 PM.
Feb 21, 2021, 05:07 PM
Team Falcon
Scrib's Avatar
Wow! That looks really nice

Guess I better contact my local distributor...

Feb 22, 2021, 01:25 PM
Oleg Golovidov
olgol's Avatar
Roger, thanks for the detailed description and pics.
e-Falcon looks very nice.
I am waiting for my first sample to arrive soon, with the next batch of Falcons.
I will report on my build also then.
Feb 22, 2021, 01:45 PM
in awe of glide...
Kirkerik's Avatar
Originally Posted by Rosbrik

And also, I can not complain about 221 gram with a 2s 450 mAh and 212 with a 2s 350 mAh battery....
Certainly not! That is very light.
Feb 22, 2021, 01:46 PM
in awe of glide...
Kirkerik's Avatar
Last edited by Kirkerik; Mar 17, 2021 at 02:33 AM.
Mar 07, 2021, 12:35 PM
Registered User
luv2flyez's Avatar
Very nice model, is it available now?
Mar 07, 2021, 10:13 PM
Oleg Golovidov
olgol's Avatar
Yes I will he taking orders for it
I received my first sample and will be building it now
Mar 08, 2021, 05:43 PM
DS Junkie
Screamin' Eagle's Avatar
If this model is half as good as the F3K Falcon it will be a tremendous success!
Mar 09, 2021, 06:32 PM
I know the Inside out.....
Thread OP
Originally Posted by Screamin' Eagle
If this model is half as good as the F3K Falcon it will be a tremendous success!
I have now flown it several times and also next to my Falcon F3K to see how it compares.

Belief me, it is as good as the Falcon F3K. It signals thermals very well and circles very easy and steadily - just like the F3K.

Mar 14, 2021, 12:41 AM
Registered User
Hello from Japan.

Here I attach pics of my EL example.
I have 3 Falcons (2 x Regular + 1 x Windy) and love this type very much.
Now I added EL (2 piece) to my Falcon fleet.

AUW 230g (+CG ballast)
Wing: 95g
Fuselage (without battery): 112g
Battery: 23g (Hyperion 7.4V 320mAh)
Servos: 1 x X06 for elevator, 3 x BMS-101DMG for the other surfaces (this cheap servo works well)
Motor: T-motor F1507 (2700KV), CN 6x4 prop
CG: 62mm
Flap settings: Speed: -1.5mm, Cruise: +1mm, Thermal: +3~7mm

I used ballast holder as gear tray.
Glued servos on it and fixed with screw to the fuselage.

Ballast hook is my idea, and it was not so bad. I made 30g & 15g ballasts with steel Car RC ballast blocks.
I will make more heavy lead ballast, because I often load F3K version up to 140g (390g, Windy) and the Falcon flies quite well even when carrying heavy ballast.

Flight performance is nothing but Falcon, exact same as F3K version. I love it.
However, handling characteristic seemed better than F3K version.
I presume the causes were short nose and light wing tips.

Thank you,
Mar 15, 2021, 10:01 AM
Oleg Golovidov
olgol's Avatar
Yasu, thanks a lot for posting the pictures and description.
Quite an interesting arrangement, very innovative.

I have yet to start on mine.
I got me KST-06 servos from Thomas.
Have all power system components.
So all that is needed is some elbow grease, i.e. I need to get off my lazy azz and start building it.
May 11, 2021, 08:31 PM
Registered User
The Tellurian's Avatar
Originally Posted by olgol
Yes I will he taking orders for it
I received my first sample and will be building it now

Anything happening on this front?


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