Flitetest X-57. Take 2.

...a long time between drinks

After a long hiatus the X-57 is back in the air and flying OK.

The issue I'd had initially with unbalanced thrust turned out to be only an over-tightened motor mount - backing off a couple of screws was all it took to get the slow motor spinning up to speed.

However, the wings still seem to be generating too much lift, with the X-57 soaring with even modest throttle settings and fairly wanting to loop with anything more than that.

In fact, I had to fly it with negative elevator trim just to try and get it flying level-ish. For my next try I'll use a heavier 4S 3000 to try and even things out a bit.

This may help it fly level and so help to eliminate the problem of the big disparity between power on and power off flight and allow it to glide properly with a bit of airspeed. At the moment when you cut the throttle it stalls which makes trying to land it, well trying...

FT Baby Blender. Re Maiden !!

...a super bipe

I had long wanted a bi-plane and, having been bitten by the Flitetest bug, I decided that the Baby Blender would be the one for me.

Having built it and checked the CG I discovered, as I have with a few FT planes, that it was tail heavy and therefore I decided to fly it with a 2200 battery to add weight to the nose.

In addition to now being heavier, for the first time I used an "all-in-one" pack from eBay which, at about the same cost as making the plane, I thought a perfect fit. Unfortunately the Baby Blender turnout out to be pitch sensitive, either going up or down in a hurry with no happy medium achievable.

Also unfortunately, the eBay motor popped after only a few minutes, leaving the overweight bipe to plummet earthwards.

Fast-forwarding several months, I eventually replaced the Blender's motor and also gave it a covered lower cowling, something I'd tested with success on the FT 3D. Also, I decided to go with a lighter 1800 battery and see what happened.

The combination turned out to be a winner, the lighter-weight FT was still stable and now with a much lighter nose it quietly floated around the field once I'd set the elevator trim down a little; it headed for the skies so much lift was it generating!

The only change I made from the first flight was to increase the aileron throws a touch. Apart from that all good, and I'm looking forward to many more flights peacefully punting the little bipe around the oval...

FT Cruiser X-57. First Flight.

...hey I made an X-plane. sort of...

Having seen NASA's intriguing X-57 Electric Research Plane, I decided to converted Flitetest's twin-engined FT Cruiser into an RC version of NASA's experimental plane, featuring twin electric motors mounted in the wingtips.

The X-57 actually features 14 motors, twelve small motors with folding props mounted in the leading edge of the wings providing supplementary power for takeoff. The two larger motors installed in the wingtips provide the high-speed cruise propulsion.

I wasn't going to be wiring up fourteen motors, so I dispatched with the dozen leading edge units favouring the simpler hand-launch solution. I used small 89W quad motors (1806 2300kv) running at on a 3S 2200 battery. The propellors are 5x3 props, swinging inwards sweeping air onto the top of the wing to counteracting the wingtip vortex.

This is one of the main benefits of the wingtip design, a second being that the concentrated wingtip flow feeds into the propellor, increasing the dynamic thrust. Finally, additional thrust is generated by virtue of the outside sweep of the prop being unimpeded by the presence of a wing; the prop wash goes into free air.

The modified FT Cruiser with weighs 940g all up, or 749g without battery compared to the spec mass of 766g. The 17g difference is due to reduced wing size, one less servo (rudder servo ditched in favour of differential thrust) and smaller motors. However, 7g ballast had to be added to the nose for CoG correction due to the motors being set rearwards compared to the standard Cruiser configuration.

The motors generate a combined 710g of thrust as installed, sufficient for cruise but certainly not 3D flight. Static thrust of a commercial aircraft is a quarter of its loaded weight and around half of its empty weight. In the case of the xCruiser this would equate to 235g to 470g respectively. So it's comfortably powered in aircraft terms although less so in RC terms where closer to 100% is nice-to-have...

Fun With the FT Viggen.

...fast and fun

The Viggen has proved to be a great addition to the fleet, being fast stable and distinctive in the air. And, all this despite it being my first Flitetest build.

Most amazingly is how easily, and stably, it launches; being flat underneath you have to launch it underhand and yet it climbs stably without threat of stall or spin.

It's benign characteristics are a combination of it being a delta, but also certainly due to the calming effect of the canards, keeping the nose up and reducing the load on the wings.

You can turn the Viggen as sharply as you like and it won't do anything nasty. In fact, so effectively will it turn that it's almost like it has vectored thrust, being able to keep on looping almost about its own length.

And it's quite quick too; my version runs a common-or-garden ebay fan with a 50A ESC and is good for about 100kph. You could load it up with a 12 blade fan although I'm not sure how much aero load you'd want to put on a foam board plane...

Flitetest Viggen. First Flight.

...no bites from the vegan

Preparing for the first flight of the FT Viggen I was both excited and nervous; it looked to be a great flying plane made a little more forgiving with the canards. However, having a completely flat underside, it was also the first plane that I’d ever have to launch underhand.

So, as I’ve done several times before, I headed into the depths of the paddocks to a launch spot with long grass, just in case I needed an arrestor bed. As it turns out not really but it didn’t hurt since, at my first attempt, the trajectory was too flat, and the Viggen simply disappeared gently into the foliage.

The second attempt was good, the Viggen holding an upward attitude till I could bump up the throttle and then it was on its way.

Flitetest Nutball. First Flight.

...a well rounded plane


Whilst waiting for parts to arrive for the completion of the Viggen, my first Flitetest project, I decided to do a Nutball from a spare sheet of foam and a scrap motor.

It's a very easy plane to make, much simpler than the relatively complex Viggen, so didn't take long to make at all.

However, I didn't like the front-mounted motor or externally attached battery, which I thought looked ugly, so I mounted the motor internally and made access to the power pod through the top of the plane.

The result was a much neater-looking plane however required a much bigger battery (a 1300 3S) in order to compensate for the relocated motor.

With a big wing area I didn't think this would be a problem, however it turned what should be a slow floater into an absolute handful of a plane. Additionally, the elevator/rudder setup seemed highly ineffective with the Nutball not wanting to turn much at all. In fact, overall, flying the Nutball it recalled my first flights with the nose-heavy Radjet. 

By the end of the second flight, which ended with the Nutball spiralling into the paddock, I'd decided to reduce weight with a smaller battery mounted on top, and to change to elevon mix layout to improve flight response...