Wednesday, June 19, 2013

Small xQuad

Well its now winter here and the day are short and the weather crap. Which means not alot of time to learn to fly out doors, and a novice flying a 450 indoors will end is expensive tears. So decided to make a smaller sized Quad.

I finally got some 7x3.5 tri props, a Q-Brain ESC and some SK3 1275 motors from Hobbyking (3weeks shipping).

I measured it out on the grid to see what size I need to make the frame, it came out to be 280 prop centers,

Next up was to make the frame, I decided to use 10mm U shaped extruded aluminum as its easy to get and easy to work with. I cut to length then measured the center so I could cut down 50% with the hack saw and then file out two slots on each frame so that I could  then slot them together and have a flat x.

First cuts made next was to use a small file to make them as wide as the side walls of the U shaped  aluminum.

After the cutting and filing the boom slotted nicely together. I drill a hole in the center and used a small 3mm bolt to hole then tightly in a perfect 90degree x, then used CA to help make sure there was no movement.

I started to use this plastic container as a base and zip tied the booms to it and got it to flying stage before I changed direction and used the spare plates I had with the spare part Rctime 450 frame.

The motors were all lock-tighted to the prop adapters and motor mounts. I then used zip ties to hold them to the RCTimer boom motor mounts. This part of the frame (Booms and motor mounts didn't change when I we to the plates)


I stuffed up ..... grrrr

I somehow while using the excellent eCalc I got the props , motor, weight combo wrong. So when the above quad was finished it took about 70-75% throttle to take off ..... guttered.

i went back and checked my inputs and found that with all the permutations I was inputting I had used APC Slowfly for the prop details, once I used GWS which is what the props I got were ... it showed 66% for the estimated weight.  So with is a little heavier 70-75% was what I ended up with.   So back to the drawing board.

Luckily when I ordered the SK3 1275kv motors I made sure that they could also spin 8x4.5 as I plan to also make a hex using these.... lots of plans :)

So I ended up using the spare plates form the spare parts of the second RCtimer frame I purchased ... hey it was on sale and it was the cheapest what to get replacement arms, which I have already busted one of.

I zip tied my x frame with motor mounts on to the spare plate. I then used double sided tape to mount the Q-Brain to the underside. All was looking great. However with the size of the Q-Brain and the need to put on the heli landing gear and battery I then decided to also add the other plate. I just used nylon stand offs. See I knew all that extra "stuff" I used to maximise shipping would come in handy.

Using the 8x4.5 props was a tight fit, I had to slide the motor mounts out 5mm, but the fitted and it took off about about 45% throttle. I was much happier.

So I now have a smaller "indoor" quad. But I soon found out smaller means twitcher ... But its all good pratice.

 The small Quad on 450 for size comparison.

Finished Quad.