Finally, a L/G design that might work!

I got some time to work on the landing gear and came up with a design that gives the desired look and motion, while still being lightweight. I bodged together a prototype that kind-of works. Photos below.

Showing gear in stowed position.

Showing gear in deployed position.

I'm hoping that on the real thing; I can have the vertical piece on a sprung slider, to give added effect and possibly some shock absorption upon touch-down. This really needs a video...

It'll happen when it happens...

My local hobby shop (Power Hobbies) called to say the plastic sheets I'd ordered last week, had come in. I now have 10 sheets of 0.25mm, 10 of 0.5mm and one of the thicker 2mm (all approx. A4 size), so I can go ahead and create the fuselage, in theory.

Damn meerkats have hogged my time recently, on top of my studies, but I'm determined to break this gear issue and make some progress. A friend said they've given up worrying over progress of their projects but I can't help beating myself up over how long it takes me to get anything done.

I had a little time!

A couple of weeks ago I managed to get some time (at a SHDC meet) to hack together some bit-banging code on a PIC to control a RC servo. This crude code, in theory, will allow me to control the servos for the landing gear, nacelle steering and of course the EDF thrust.

I had a little time over Christmas to discover my planned landing gear redesign was halted by my inability to mill a tidy slot in some aluminium channel with my tiny little lathe/mill combo. I need to come up with a simpler mechanism, get the gear done and put some kind of external skin on the airframe, then I can get to the control system!

Joost doon't 'ave the poower!

I made the adapter cable with the Deans connectors (cut off the end of the umbilical) and 4mm bullets fitted to mate with the Li-Po. I didn't know how charged the battery was, but I had to try it...

With just the battery (no extra weights) I powered up and "hovered" for a minute or so; all 3 EDFs running and plenty of power. I then added the 2 blocks of metal again. These are just bits I've been using to help in the construction so far, as weights or a square-edge. So powering again, it got off the ground but was obviously loaded. Second attempt and it just got off the ground and I hit max on the controller. I backed off, then tried again - now barely lifting. I took off the heavier block and re-tried - only slightly better. The battery must be dead! As I said; I don't know what the state of charge was beforehand and the charger hasn't arrived yet...

Disheartened by the sub-60 second runtime, I was thinking the battery couldn't have been charged. I wasn't expecting much, maybe 2 or 3 minutes. I also thought I should check and quantify the "other stuff", so went off to weigh the 2 blocks. They were a lot heavier than I thought: the larger block of aluminium was 335g and the smaller stainless steel block was 414g! For comparison, the battery is 408g (listed as 412g). That made me feel a little better; I'd added a lot more than necessary, an additional 759g (1.65lb for those working in old money). So fingers-crossed; if I can keep the weight of all that "other stuff" down and with a fully charged battery, it might just work... for a couple of minutes.

Battery and tail

A colleague pointed out that I should get a battery sooner rather than later, so I don't waste my effort if the battery can't provide enough juice to lift off. So I ordered one: Li-Po 5000mAh 20C, 30C for ten seconds. That's 100A continuous and 150A burst. Doesn't sound feasible! We'll see.

I got the upper tail fins finished and fitted. They're mostly for show. They may help in forward flight, but I'm no aero-engineer. I'm working on gut-feel!

With as much as possible fitted and two lumps of metal for "some other stuff", it weighs in at 2kg.

Clarification

I thought I should clarify that although I'm using some RC gear, I'm not using RC in the traditional sense. I have no transmitter or receiver as a couple of MCUs will be doing the work, these will have a radio link to a base station of some kind where the operator can monitor and guide the aircraft. Any operator inputs will feed in to the control loop as error offsets rather than direct control of servos. At least, that's the plan...

More parts: sensors and transceivers

Thanks to the guys at Sparkfun I'm now the proud owner of three Maxbotix LV-EZ0 ultrasonic range finders and a pair of nRF2401A transceivers with trace antennas. Now the only thing stopping me is time (and perhaps my coding skills) as I have all the main components I need to get things flying, but between work, studies and family my spare time is limited. I ask anyone following this to please be patient, and keep sending words of encouragement!

Follow the video from the previous post on YouTube as it links to some other interesting videos.

I'm going to attempt to finish the tail this week and start work on the control system.