Willy Nillies Simple 250
Background

For the last couple of month’s I have been working on my second Willy Nillies Ace Simple 250. It is a balsa kit that is sold by Willy Nillies. I decided to build this airplane a second time since it’s a fun plane to fly. It’s lightweight, small, and very acrobatic. Despite having “simple” in the name, that only refers to the construction. The flight characteristics are quite “advance” in my opinion.

There were a things I wanted to change during the build. My goals were to reduce the weight, and to do a better job during the construction so it flies straighter. My previous Simple 250 weighed 263 grams. The design goal of this kit is it should be under 250 grams, since that is the weight limit of rc airplanes if you do not want to have to register with the FAA. I regularly fly larger aircraft, so being a little heavy and having to slap a number on the airplane isn’t a huge deal. However the lighter you can build an airplane, the better it will fly. My previous airplane had a twisted tail. While it still flies with the twisted tail, it’s annoying because the airplane does not react in ways that you expect.

For a little back story on the Willy Nillies plane, it is based on a the Ace RC Simple 400. From what I can tell, it was a kit that was made in the 2000’s. It’s original design called for a 400 size brushed motor. The kit has been discontinued, and brushed motors have gone the way of the dodo in rc airplane hobby. To me these airplanes take a lot of inspiration from the infamous Ugly Stik design. Much like the Ugly Stik, it has a boxy fuselage, no canopy, and a simple wing shape. The Simple 250/400 are belly landers as well, so there’s no landing gears to worry about. The airplanes focus on simply being an rc airplane without any kind of scale detail to a real airplane.

Construction

Assembling a Willy Nillies airplane is what I call “mostly” straight forward. The kits do not come with detailed instructions or plans. There are certain points where it might feel like a jig saw puzzle wondering where some piece might go. Thankfully there is an active forum and Facebook community of others working through these kits. Doug, who owns Willy Nillies and creates the kits, is very active on these platforms and will regularly chime in. He seems very passionate about his kits and providing people what they need to be successful. It seems like most questions get answered very quickly.

For being my second time building this airplane (and my third Willy Nilly plane) the construction was fairly painless. It still took me a couple of months, but that’s because I kept my build sessions short this time around. By the time I was done, my airplane came to an all up weight (which is the weight of the airplane as it’s ready to fly) of 220 grams!

Below is a comparison chart of the components used in my older Simple 250 compared to my new one.

Component Old Simple 250New Simple 250Weight Difference
ServosEmax ES9051 (5g)Hitec hs40(4.8).2g
ESCFlycolor Francy 20A (12.5g)ZTW Mantis 12A (10g)2.5
RadioAR6110e (4.3g)FrSky G-RX6 (2.6g)1.7
MotorEmax EMAX RS2205S 2600Kv (30g)BETAFPV 1805 2250kv (16.2g)13.8
Nose weight16g8g8
PropellerAPC 5×3 dual blade (6g)iFlight Nazgul 5×3 tri blade (3g)3
Calculated Weight difference29.2
Actual weight difference43

There’s a slight discrepancy between expected an actual weight difference. Could be variation in wood, differences in glues (first build I used CA glue, second I used wood glue). But I won’t complain too much that I came in lighter than expected

For both builds I am using the same 3s 350mah 75c Tattu battery. The

Old Simple 250

Ace Simple 250

New Simple 250

Ace Simple 250

Flight Day

The maiden took place on 3/4/2021 at a park in Vineyard, Utah. The weather was about 48 degrees and the wind was around 5 knots.

Vineyard, UT field

Willy Nillies Simple 250

The bottom of my Simple 250. The checkerboards really help differentiate the top and bottom of the wing when flying.

Ace Simple 250 bottom

The flight went really well! The airplane required very little trimming. It tracks straight, and was a joy to fly.

One minor issue that I should have thought of before maiden day was using the tri-bladed propeller. The manufacture of this motor recommends a 3 bladed propeller, so that’s what I got to start with. I didn’t think about how the blades would rest below the aircraft when it belly lands.

Here’s a picture of the propeller
5x3 triblade

Normally for a belly landing you configure the ESC to brake the motor to reduce the spinning (doesn’t always stop the propeller 100%, but it gets rid of a lot of rotational energy), then when the prop hits the ground, it does so with a low rotational speed (which greatly reduces the chance of damaging the propeller), then it gets out of the way while the belly slides. This particular propeller is inappropriate for belly landing since there’s no orientation where no blades are striking the ground. However the airplane came in at a slow enough speed to not cause any propeller damage. I’ll still be replacing it though.

I flew with a friend today

I also brought out my Funtana to fly as well. Both airplanes fit in my trunk.

Flight Footage

I do have some flight footage, but I didn’t get any the day of the maiden. This video is the next day. The weather conditions were almost identical which were about 50 degrees, 5 knots of wind. I tried slowing it down too much in the landing causing it to stall it and fall. With these little planes, and their light weight they can take little mishaps since there’s not a lot of energy to dissipate in a low speed crash.

Summary

In summary my second Willy Nillies Ace 250 is a successful build! It’s built straighter and significantly lighter than my older airplane. I’m very happy with it. I’m not sure what I want to do with my old airplane now, maybe I’ll strap a rocket to it or do other fun/crazy things with it.


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