June 27, 2014

Prop and slot on the Bixler

I mentioned earlier that I tried to change motor to a slightly higher Kv while keeping the same propeller as before to slightly improve the top speed and static thrust. This while at the same time removing the motor mount upgrade which gave the Bixler some strange flight characteristics. However, despite what I had measured with the greatest of precision the 7x5 prop would not fit with the lower mount.

Well, I had to do something. Why not some cutting? I cut a slot into the tail to give the propeller the clearance it needs. This came with a small surprise, the tail is like a hollow tube.


Bixler propeller slot
Tail slot with propeller

I knew that this cut would impact the already not-so-rigid tail of the Bixler. And it did, most notably. To counter this I added two carbon fiber rods closely to the newly cut slot. This is in addition to the earlier upgrade of the tail with a carbon fiber rod on the bottom. With the three rods in place the tail is now very rigid.

Additional carbon fiber rod
Carbon fiber rod enforcement on the tail

Since I used a pusher prop before, and the 6x4 one I tried was not I had to switch a pair of cables to make the motor turn the right direction. There is no real advantage to having a pusher prop on a plane like this except that you don't have to locktite the nut on the propeller shaft.

June 22, 2014

Badly packed stuff from HobbyKing

I got a package from HobbyKing today! Always feels like Christmas when a package gets delivered. But seriously, get your packers to do their work a little better! It looks like they've just thrown everything in there with. Considering that it contains 6 LiPos this is not fantastic treatment...


HobbyKing packing style

Bixler FPV

I've started my work on an FPV addition to my good old Bixler v1.1. I've flown this plane quite a lot. And crashed it a lot, being my first plane. I still love it and have no intentions on retiring it and therefore it will get some new stuff that might make it fly better and be able to teach me fixed wing FPV.

The main goal is to

  • Add a simple camera and video transmitter to the fuselage
  • Improve the motor configuration to give it some more thrust
  • Split the power distribution into three circuits (ESC,BEC,FPV) but with one battery

FPV


First off is the LC filter. I've had some bad experiences running without a filter and it seems random whether your other electronics will cause interference or not. From now on I will just add the filter from the start and be done with it already. This is the typical LC-filter. A coil and a capacitor from ebay, just like that.

FPV LC-filter to kill off any interference from the ESC or BEC.

This is the Bixler FPV mount from HobbyKing. I've had this in the drawer for over a year now. It comes together better than expected and fits fairly well. I could have done a better job on the angles of the forward support but it'll work just fine.


HobbyKing Bixler FPV mount

The camera, a Sony Super HAD-II off of ebay. Everyone says it's great and that's enough for me. I've only used Fatshark cameras up until now and I'm not impressed with them. This camera is half the price and from the comparisons I've seen it should be twice as good. I'll see for myself in the near future...

Sony Super HAD-II board camera

The camera mounted on the FPV mount. Anyone how knows more than what I knew at the moment will notice that it is mounted upside down. I learned that much later. But no I know too.


FPV mount with board camera

Everything in place on the FPV mount. The camera is still upside down on this picture, guess I haven't realized my mistake yet. I also did another mistake while putting together the power cables for the video transmitter. I mistakenly connected power and ground on the output side of the video transmitter. This particular transmitter has a 5V output on this connector. If i hadn't realized this right before connecting the setup the the battery I would probably have had a pile of carbon on the next picture.


FPV mount with filter, transmitter, camera and antenna


FPV mount on the Bixler. Without the rubber bands to hold it in place.


Motor upgrade

The previous setup was a 950Kv motor and a 7x5 prop mounted on an extension to place it higher up to allow for a bigger propeller. This setup was very power efficient and silent but I had much less static thrust and a low top speed. The top speed is not really an issue but I would like to more thrust for easier take-offs. The mount also had some weird effects on flight characteristics. The plane tenden to tip forward on low speed but acted as if it was tail heavy in cruising speed.

I removed the extended mounting with hopes of having enough free space to be able to keep the same prop but with a faster 1250kv motor. This was not the case and I've now put on a 6x4 prop instead. It does not give me the thrust I would like during "bench testing" and I will probably need to work some more on this solution.


Power system


I wired up a new power system including an e-fuel gauge and cabling for the ESC, BEC and a JST connector for the FPV mount. I had some issues with heat from the ESC before but I suspect that it is mostly from the built-in linear BEC. Using an external switched-mode BEC should solve this problem.

Bixler power system






June 3, 2014

KK Flight controller from dx

I just received a KK 5.5 flight controller board from dx.com. I didn't order this board, in fact I ordered an USBAsp but the item was mislabeled in the warehouse and I got a controller board instead.

I wouldn't have ordered this in the first place since I've gotten used to flying the CC3D which is much better. And after having seen this board I'm even more skeptic to these cheap boards.

As you can see from the pictures the board is dirty. Very dirty. It's as if it has already been used, gotten wet and left to dry without cleaning. The soldering looks alright, with the exception of a few components which are not mounted straight.

Now what to do with this device? Maybe I should try it in my upcoming Bixler FPV build to get flight stabilization...

KK 5.5 Board, top side

KK 5.5 Board, bottom side