Drone build progress.... Will it fly?

 

Well it's been a few months since my last blog post, so here is an update and some photos.

 

The ground control trailer is going well. I have finished putting on the steel cladding, and insulated with 10mm foamboard. In my last blog post, I referred to a generator which I was thinking of including.....I have decided to leave it out of the build, as I have decided to use two car batteries, 100W solar panel, and the tow car's alternator as a last resort to run the 2KW inverter. Should be plenty of power. The generator would be very loud if I incorporated it into the build, though it would allow me to have air conditioning, which would be nice!

 

 

 

 And a vid never goes astray, subscribe for more :-)

 

 

 

 

 

 Now the plane is taking shape too. See previous blog for the solidworks drawing. Basically it's an aluminium skeleton made from box section, and hot wire cut foam wings. The wings are 3m tip to tip. and there are two 16mm tubes joining the tail plane to the wings. The fuselage is a work in progress, but it will probably be made from water jet cut 3mm aluminium, then bent into a box.

The wings are cut from "medium density" insulation foam. The local insulation shop had offcuts of a suitable size, which they parted with for $30. Nice!

This is my first build of this size, so I really am not sure if it will be strong enough. Time will tell!

 

 

 

That's a two car garage, so the build is getting bigger and bigger! 

 

 

 That's a CRRCPro 50cc two stroke gas engine. It's a low cost Chinese engine. Reliability? Yet to be proven, but I can only find great reviews online, and only one unhappy review from someone that didn't like the BOX it came in?!?!?!

 

 

 

 Landing gear, and motor mount fitted. Servo compartments cut... 

 

 Now for the fun part (NOT) ... fiberglassing!

I purchased some fiberglass cloth from ebay. It was the remains of some stock used for building wind turbines. So I thought it would be perfect...... Well, this stuff is strong, but it is VERRRRY heavy... The tail plane alone, after the fiberglass treatment, is 4KG! So the entire aeroplane will weigh around 20Kg before I add a payload, electronics and fuel. Too heavy? Again time will tell!

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Comment by Jesse on June 9, 2013 at 6:28am

if I may; I think that you're going to come up short on power with your current setup!  two car batteries are around 120AH total, that's 120 Amps for 1 hour.  assuming that they are in perfect health.  I'd wager that it'd be much closer to 100Ah or less.  best case 120A x 12v (again an optimistic assumption of battery voltage under load) is about 1440W for an hour.  I would budget 1000W against one hour to be on the safe side, again optimistically 250W for 4 hours... 

you might be much better off stocking your GS station with a couple of N70ZZ deep cycle batteries designed for mobile home's or 4WD'ing, giving yourself a true 200Ah supply.

to work it out more accurately, power your inverter and measure how much energy it draws just sitting idle, you might need to plug in something to make it run the inverter circuits & keep it out of standby mode. multiply it by the battery voltage and you've got roughly how many watts it costs to run your inverter (it changes slightly depending on load) be sure to add this value into your other calculations (eg; monitor(s), laptop/desktop, chargers, power tools @ estimated usage times) this should tell you how much power it will take to run your ground station, multiply this by the time you want to use it, with some overhead.  then divide by battery voltage, and you should have a rough guide as to how many/big your batteries will need to be...

sorry if this is hard to follow :-S 


Admin
Comment by Morli on June 9, 2013 at 10:46am

Tnx Jasse,

that was good/easy explaination

@ Phil,

I think you are looking at wrong FG cloth.  look at thisone from HK. I bought this with the same idea in mind that you are currently doing. I am sure my tail and whole fuse would not be this heavy. There r other choices 1 & 2 of weight of FG also from same outlet. Also good  collection CF tubes r available, i bought 2 of each for R &  D. Also the choice of resin makes the difference in finish and weight I was told. I haven't explored those yet.

I choose RCGF eng over yours. They were similarly priced but I had first hand  view of RCGF before ordering and I like it. I have 15cc and 26cc of which 15 cc has done some airtime. Like Jasse said, IMO 50cc may be under powered for the TOW u mentioned

Good Luck

Comment by Phil P on June 10, 2013 at 2:36am

@ Jesse, I will be in a position to monitor the current drawn from the monitors and PC in about a week or so. I'm hoping it will be about 35W per monitor and about 200 to 300 watts for each PC, so 650W total. It only has to work for say two 30 minute flights, and remember I can just plug it in to the car's alternator. The monitors don't have to be all on if not required. I'd say it's enough, but will definitely go for deep cycle batts if its not.

@Morli,  thanks for the link. I finished the second wing today, and yes, it feels very heavy. I won't paint anything and ill try to get this thing flying within 2 weeks or so... If it's too heavy, I'll remove the FG and get the thin stuff. Not looking forward to saying bye bye to all the hard work and $$ I put into the thicker FG and epoxy...

@Mikel-Ange  Good to see I have inspired someone to do the same. I live in a small apartment, so the GCS trailer doubles as storage for the aeroplane. We have a baby, so the car is always filled up with baby seats and prams, so while it looks like it is over-the-top in many respects, it actually is quite practical and allows me to leave to an air field at a moments notice. No need to remember to pack the tools, or the PC or plane parts, as they are all in there already!


Admin
Comment by Morli on June 10, 2013 at 10:24am

Good Luck Phil.

The aluminum tail tubes worries me. they will wobble. Better replace them with some bigger dia CF or FG tubes now than feel sorry later. 

Comment by Phil P on June 10, 2013 at 6:18pm
Thanks Morli. I might take your advice! The 16mm tubes looked ok till I started adding weight to the tail plane

Admin
Comment by Morli on June 10, 2013 at 9:38pm

Phil,

I started a similar build few years back and did not have access then  to CF tubes from HK for dia of my choice. I found FG fishing rod in the junk room. Took two of the appropriate dia section of the telescopic fishing rod and used the build. It looks fine but the  build is in back burner some were.  Cheers

Comment by Jesse on June 18, 2013 at 8:37pm

@Phil - I think you'll be pretty close on that.  you'll probably get two half hour flights.  With the car, most car alternators will supply 80A of power at full power (say 2500RPM/Highway speed) at idle they're usually flat out just powering the accessories in the car.  if you are going to use the alternator in your car, get yourself a battery isolator just in case!  and consider ways to set a fast idle.

 

it might also be worth while looking for a small 12v generator and tying that in to charge your batteries directly? 

Comment by Phil P on June 19, 2013 at 12:31am
@jesse, nah should be ok. I measured the current draw of the PC and it is only 110w when working hard, drops to 80w when idling. Running APM planner isnt very intensive. I haven't measured the actual current draw of the monitors but they are going to be quite low. Also alternators in new cars have come a long way in the last few years. They regulate much better at low rpms. At this rate, a sunny day with the 100w solar panel will give me many hours of flight time without running the car.
Comment by Tyrell John on August 18, 2013 at 8:24am

Interesting...I'm also building a drone 3.2meter wing span. I'm trying to keep mine as light as possible. 1hp nitro engine wanting to get 8 hours flight.

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