...fine tuning the floats
Having done a water test with the Trainstar floatplane I've been researching techniques on launching floatplanes. In the process I came across more detailed sketches of floatplane configuration which caused some concern regarding how I'd installed the floats.
While I'd got the basic setup correct, with CoG in front of the step and the front of the floats ahead of the spinner, the proportions weren't right, with the CoG being too far ahead of the step (around 45mm) when it should be about 10mm, and the tip of the floats was about 25mm ahead of the spinner when ideally it should be greater than this.
The setup and installation of the floats is quite fiddly and awkward so I wasn't really keen to repeat the experience, and additionally moving the floats would mean a set of open holes in the floats which wasn't desirable.
However the rationale behind the setup criteria were quite compelling; having the CoG too far ahead of the step means rotation during takeoff is harder, and having the floats extending further forward reduces the risk of the plane capsizing which, despite having invested in a rescue craft, is a highly desirable feature. Finally, and perhaps the deciding reason, was that the Trainstar's CoG was in fact a little far back, which would be corrected by moving the floats forward without needing ballast, something I absolutely don't want to do.
So I bit the bullet and uninstalled the floats. I'm still in the process of attaching them about 30mm forward, however this position has adjusted the CoG perfectly in terms of the step and the floatplane as a whole.
So, I just need to finish off the screws and the seal around the mounts, and do a bit of sealing of the unused holes and a cosmetic touch-up. The weather has been terrible lately, so I might just pop down to the local pond again and do another water test, this time perhaps trying to get the Trainstar planing more and, perhaps, even airborne for a few feet to give myself a bit more confidence...
...and a blast as well!
This morning was overcast and with a hint of drizzle and some breeze around, good enough to fly so I took the Radjet along. It has been flying best-ever recently, despite it's thoroughly battered appearance, and this morning it launched happily and climbed into the sky.
It looked like a pleasant morning's flight was in store when, out of the blue, the Radjet went into a severe stall and started to tumble. A few flicks of the control showed that I wasn't going to be any help, so I cut power and let the plane flutter down. My first guess was one of the control linkages had come loose but, on inspection, all was fine. The canopy, however, was nowhere to be seen...
Having flown for all of twenty seconds I was loathe to pack up and head to work, so I decided to give the Radjet another go sans canopy. Just in case, I launched the plane over the long paddock grass to act as an arrestor bed, however this proved needless as the Radjet climbed steadily.
In fact the Radjet flew well, very well in fact, seemingly faster than ever without the weight of the canopy. Also, with battery moved toward the centre of lift to correct the CoG, the jet was more agile and manoeuvrable as well.
In fact the Radjet was flying so well the throttle was soon at maximum and stayed there for the whole flight, the jet carving up the sky, soaring and rolling, until the motor note began to drop and I turned the plane in to land.
Walking back to the car I spotted the taped-up canopy lying on the grass. Well, I don't think I'll be needing that again...
...followed shortly by misfortune
After completion of the now-routine crash repairs, the Radjet was up for its first flight with all mass balance mods completed, giving it the best possible chance of flying decently.
A gentle westerly was blowing as I launched the Radjet on max power, helping it climb quickly into the overcast sky. Happily, I soon discovered that the Radjet was now flying much better, although I still had it blasting around the skies of full throttle as I was still concerned about it losing lift and stalling. However, after a few heart-stopping episodes, I managed to calm the beast down and bring it in nicely for a good landing.
Reflecting on the flight I realised that, with it's improved flight characteristics, I no longer needed to be flying it at full pelt just to keep it in the air, so I decided to give it another go at a more moderate pace. Finally an opportunity to experience how the Radjet should fly...
Which, I can tell you, is really very well. It's stable, fast and responsive, with a super-high snap roll rate with just a flick of aileron. Also, its now docile enough to be able to fly around at moderate throttle settings. So all good except that, as I made a circuit of the field, the Radjet passed behind one of the trees. Now this is a common enough occurrence that has happened frequently with the gliders. But this wasn't a stable-flying glider...
After a second with still no sign of the little plane I ran to the fence for a better view, occasionally feeding a bit of elevator in the hope keep the plane from crashing. As I stared across the paddocks hoping to catch a glimpse of the Radjet in flight it was as if the plane had vanished into another dimension. It had just disappeared!
Not for the first time I climbed through the barbed-wire fence and went walkabout in the paddock. The cattle had fortunately gathered to graze at the far end so there was no trouble from them, and I greeted the curious observations of the kangaroos with a friendly hello.
After tramping through the swamp and up and then down the hill, I finally spotted a small orange fin of Radjet sticking above the grass. I hoped that gliding down without power it had managed to land without incident, however on reaching the plane it was clear this was unfortunately not the case: the nose was almost completely ripped off and the fuselage splayed open. In fact it exhibited the classic "peeled banana" look as if there had been an explosion in the cockpit.
Still, at least it would be repairable with the usual suspects, super glue and fibre tape...
...but not necessarily together
The Radjet is now glued together again and ready for another fly. This morning would definitely have been too breezy for the little craft, however I'm keen to get it into the air again for a bit more high-speed fun.
As far as mass-balance is concerned, I'm now packaging the receiver into the fuselage as well after the battery, and I've put a couple of screws in the rearmost section of the fuselage so as to get the maximum counterbalance for the minimum weight, and without disrupting the airflow.
I have also received the new micro SD card for the wing cam, a class 10 U1 speed rating. I'm not sure that the U1 rating will do much in this application as I gather it's some sort of software driven feature aimed at mobile devices.
Anyway, it won't do any harm. I'd love to put the camera on the Radjet however, considering its delicate balance and propensity for crashing, I think we'll reserve on-board video for the Walrus and Floater Jet...
