Ground Control Trailer and Drone build. Part 3. Lots of changes!

See blog 1 here, blog 2 here.

So this is blog number 3 of my home made Ground Control Trailer build, and home made drone build, and as the title suggests, I have re-designed quite a bit of it on the fly.

Firstly, the GCS trailer is completely finished. All insulated, and powered up. And the old 6x9 trailer that it is based on has had a spruce up with new tyres, wheels, bearings, LED lights, safety chain, etc. Inside you can see 5 permanently mounted LCD screens. Four of the screens are connected to a single PC through a 4 way graphics card, and the fifth connected to a laptop. The idea is to use one PC for most functions, including Mission Planner, web based weather radar, and video feed, and for the laptop to serve as a backup if the main PC or data link fails. 

External to the trailer there is a 4 metre steel telescopic antenna mount for an RFD900 radio. The higher the radio, the better the range after all. I'm looking forward to doing some range tests!

Now for the drone build.

I decided that the tailplane in blog 2 was too heavy and the fibreglass that I was using was too thick. So instead of pressing on and trying to fly the plane, I made the reluctant choice to rip it all off and use a thinner glass fibre. Also, the tail plane was still feeling on the heavy side, so I made up a new one with solid flat balsa wood. Much lighter, and less drag than the foam fiberglass tailplane that I scrapped.

Also, one of the biggest changes was a complete re-design of the fuselage. The original plan was to build the fuse out of water jet cut aluminium, bent into a box. I started the solidworks model, but I couldn't get the weight down no matter how hard I tried. So I decided to go for a fuse built with 25mm box section extruded aluminium. The walls of the box section are only 1.2mm thick, so it is light, but very very strong. So strong that after building it, I feel that I have over-done some sections, and I could have gotten away with less material.

Anyways, here it is so far with a foam surround. The top cover will be corflute material strengthened with a few aluminium stringers. The entire fuse has a flat bottom, with rounded wing cross-section, so I hope that it will add to the lift generated by the wings:

Unfortunately some aluminium dust got rubbed into the wings, which makes it look like a bit of an ugly duckling in the next photo. I might paint it, I might not. Never mind, I'm not terribly interested in looks. The aim is to have a long range drone capable of carrying a good amount of electronics. Just to add to the list of changes, I changed the two rods connecting the tail plane to the fuselage. The old 16mm ones seemed to be strong, but after mounting, I felt that they were too flexible, so they had to be changed to, you guessed it, 25mm box section aluminium. It just goes to show, that even with good PC design tools, sometimes a bit of trial and error never goes astray. 

With the added width of the new fuse, the wingspan is now 3.5 metres. That 50cc engine I had planned to use is starting to look a little small for a plane which is starting to tip 25 Kg fully loaded. So my next mod may be to add another engine. One 50cc engine in a pusher config at the back, and one 50cc engine pulling from the front. A two engine set-up would ensure good acceleration and take-off time, and would also help in reliability, as only one engine would be needed to stay airborne. 

Hopefully the next blog will have a vid of the maiden flight. It might be just a few weeks away. Can't wait!

Views: 2603

Comment by Chris Riccio on August 18, 2013 at 7:07am

Holy... If I could put all my resources into my hobby this is what i'd do!

Well done!

Comment by The Sun on August 18, 2013 at 8:56am

Ill be following this for sure, really interesting and ambitious project.


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Comment by Morli on August 18, 2013 at 10:46am

Good luck Phil

for the maiden. 

tractor+pusher config sounds fine, just remember to figure out how to route the exhaust from front eng so that it does not trouble/foul  the Camera lens after all I hope camera is part of the payload :) I had oily smogged camera  which gave fogged video after few mins into the flight :(


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Comment by Gary Mortimer on August 18, 2013 at 12:00pm

That second engine will be lots of weight to carry around in the cruise, rather find a longer runway.

Comment by Bimo Bimo on August 18, 2013 at 1:20pm

Which site do you use for the web based weather radar?

How do you use the info from the site?

Comment by Phil P on August 18, 2013 at 3:07pm
@Gary, I'll maiden the airframe with one engine and a light payload and go from there. Calculations show it needs to get to 50km/h to rotate but how long it takes to get there depends on too many factors to model. Also I'm basically stuck with my RC club's runway unless I drive a long distance to get away from civilisation. The second engine adds 2kg, around 20% of the planes weight. Certainly not insignificant, but the insurance of a second engine adds positively to the probability of getting the plane back in case of major failures. So at this stage im not sure if it will have 1 or 2 engines. I'm learning that "compromise" is the most used word by airframe designers.
Comment by Chris Riccio on August 18, 2013 at 3:18pm

@Monroe Lee King Jr.

I'm not sure why he would want to enable Eyefinity on anything other than a gaming setup. That would treat all the monitors as a single large display making it difficult to manage whats on each screen (having to manually size each window exactly where you want it). Keeping them as all individual displays keeps things easy as you just make everything fullscreen on its own display.

I have an Eyefinity system (Radeon 7990) and its a nightmare for anything other than gaming. As soon as a leave a game I have a hotkey that disable Eyefinity. 6 displays connect up just fine like any other video card that would normally support just two and there is no need to enable Eyefinity mode. Windows see 6 individual displays just fine. IMO the "Eyefinity" mode serves no purpose on a productivity machine. 

Comment by Phil P on August 18, 2013 at 3:19pm
@ Monroe

I'll talk about the onboard electronics in my next blog.
In the trailer I use just a dual core PC with an older Matrox quad card. I have found that Mission planner is not very hardware intensive nor video card intensive and it works just fine on XP. The plane however has a quad core i7 full size ATX motherboard on board, but the purpose of that is classified till the next blog ;-)
Comment by Phil P on August 18, 2013 at 3:27pm
@Chris,

Yes I have to agree. For my home PC I had a very high def 30" dell screen and it was a pain constantly moving and re-sizing windows. Thats the effect you get with eyefinity and multi monitors being treated as one. I swapped that setup for 3x 22" monitors and haven't looked back. Click the "full screen" button and the application goes full screen in the monitor that it is in. Perfect. As a bonus if I close the application and re open it, it remembers which screen it was open in last.
Comment by Phil P on August 18, 2013 at 3:53pm
:-)

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