Krieger fell into a vat of toxic waste and Kriegerpus was born.
The genesis of Kriegerpus was simple. I was looking at Krieger's pod and thinking how nice and modular it could be, and it suddenly occurred to me that it would be super easy to make a hex with it. I changed the X plates to hex plates and that was pretty much that.
Most FPV hexes aren't symmetrical – the front rotors are splayed out to make room for the cams. The fact that everyone's flying so much faster now is really liberating for me. There's no need to put the cams up front for a clear view any more, just stick them in the middle and tilt them waaaay back.
One cool thing about drawing up a perfectly symmetrical hex is that its minimum size is prop length x 2, no trigonometry needed here. There's a certain beauty to the hex, since circles naturally want to nestle into a 60 degree grid. The minimum size for a 4" hex is 202mm (8"), and the 4" Kriegerpus is 210mm. So close to ideal, and so much easier to tune, no custom motor mixes needed.
Now a quick aside on miniquad design. Much of miniquad design up to now, some of mine included (but not the Fast Forward), has focused on 'coolness'. Designers made them look pretty, nasty, like a UFO, like an animal...they swept the arms one way or another instead of taking the shortest and most direct route to the motors, making them heavier, weaker, and flexier...they gave them curves or jagged edges...they laid out the motors in dead cat configurations...they made them 'aero' but not in the most common direction of flight. None of those features enhanced performance, in fact many of them hurt performance.
For me, Krieger and Kriegerpus are an acknowledgement that a multirotor is nothing but a force vector in space, and it works best when its motors are symmetrically spaced and its weight is as central as possible – that's what the code was written for. It is nothing but an arrow that pushes in one direction, and when added to gravity's and aero drag's vectors they yield a direction of flight. None of the cool looking parts of most quads contribute to that math. When I look at Krieger I think, 'never has something that looks so slow flown so fast'.
The prototype was drawn up without a 4mm filler between the body plates. That will be added to the production version. I cut arms for a 4" version and a 5" version. Alex and Jay are building the big boys.
The first build flew great, pretty close in feel to Krieger on pid controller 1 but really weird in luxfloat. Here's a quick video of me getting used to it and making like Zoolander.
I used 2204/1960 Cobras and it felt somewhat underpowered (likely 'cause I'm usually coming from a Krieger), so I switched to 2204/2300 Tigers. Unfortunately one motor wanted to stop under high throttle so testing slowed while I hunted for the culprit. I reflowed the solder, swapped the esc, then the motor, then the signal wire, then wired that motor to a different output on the Dodo, all to no avail. I finally rebuilt the whole thing with a new pdb and a new Dodo, and that finally fixed it.
Right about this time is when I got arrested for flying at my usual testing spot, so I had to bike 90 minutes each way to get this maiden in. Nothing special here, just me trying to get the feel of it. It took me a while to coordinate yaw and roll (I was rusty and yaw was more responsive than I'm accustomed to), and I didn't need to pull back on pitch as much or at all to carve turns. I only have so many 1800's so day one didn't go much beyond this. I was happy that the 2300kv motors were much better suited to 4" props, and I didn't have to go full throttle to hold altitude in sharp turns any more.
Day two and I rode to Randall's Island and flew at what seemed like a great spot. But video wasn't good beyond the trees so I just stayed close and carved around them. Starting to get the feel of it better, and really enjoying the smooth railing.
Day three, and I went to a wide open spot with just enough trees to Immelmann, and I'm really falling in love with this thing. Jay built up a 5" version, and he described it as being similar to a Fast Forward, it just wants to go and keep going. I wish I had more than 4 good 1800's so I could have more than 12 minutes of flying each time, but this is as fluid as I got on this day. As you can see I'm not yet 'at one' with it, but still enjoying it immensely nevertheless. Maybe it's the fear of a heavier, more expensive craft, but I land with more adrenaline coursing through me with this than my other frames.
Meanwhile, here's Jay and Alex's Kpus'.
I gave mine to Steve Z for a proper thrashing.
Here's Alex's maiden of his 5" Kpus.
Both Alex and Jay Dremel'd the vertical plates so that the side motor wires wouldn't have to loop around the pod. This seemed like a real sound mod so I incorporated it into the final drawing.
When I drew up Kpus I wasn't sure if it was just going to be an oddity, but the more I fly it the more I love it. It has a real tendency to lock in to forward flight and just hold speed as it screams along. Hope you like it too, the preorder page is here.