Working with composite materials can be a very satisfying experiance, but at the same time it can be a very frustrating one too. .. just have a stickup on the mold you have been working on for the past few months and you will know exactly what im talking about
but as with pretty much anything in life, time, practice and some patience and results start becoming a very satisfying experiance .. however we dont all have the time to learn all the ins and outs of working with composite materials
i remember one of my first stickups was molding a rc helicopter canopy , i really thought some sort of wizardry was required in getting the parts to seperate, needless to say the whole part ended up in the bin
times have changed , i still get the occasional stick up, especially on using new products that im not familar with, but they tend to be minor and repairable
i couldnt wait for the drive and electrics to arrive so i have assembled it with old motors and ESC's i had lying around.
unfortunately the ESC's i have are huge (30A instead of 10A) so they add extra weight and take up space ...
pretty much the same thing with the motors, the max size of the props is 9" but i only had 10's lying around so had to chop em
ive had some time in the furnace too :D and managed to cast some wheels for my belt sander ... pretty stoked for my first time
click pic for a few more
top wheel was first cast, bottom was 'third' cast as my second cast didnt quite come out right ....
ok so have been thinking of different layups on the quad sandwich , obviously lighter and stronger is the key
So what i have tried to do is a bleed , the way you would do when you do vacuum forming over a mold, but in the quad layup this would be using the bladder to push the absorbent material (kitchen roll) against the mold with a layer to stop the kitchen roll from getting stuck this is the pink perferated plastic which has tiny holes in it to allow the excess epoxy to bleed thru.
success!! i did my standard layup which is 1 carbon kevlar and 1 carbon, and then extra 2 layers on the arms ... its its weighed in at a super light 160 grams ! (without the canopy)
this frame i didnt first coat the mold in epoxy before i did the layup so it has thousands of tiny pinpricks, cosmetic not very pretty.
Its been nine months !!!!
Alot has happened ! CNC router is working great, very happy with the results im getting , the more familiar i am getting with the machine the more i am using it to do jobs around the house ... cant see life without CNC ;-)
first up is my Quadcopter , one piece monocoque frame , my personal one is entirely carbon , but im making mostly carbon/ kevlar mixes , click pic for more
iv also started work on a 3 axis camera gimbal for a light aircraft ...
it uses brushless motors for the drive , and so far its looking great
Have also been trying different speeds and feeds on aluminium
The above piece was a small block that i cast, it however is riddilled with air pockets , you can see how porous the metal is ... Reading a few threads on the net about metal casting really made me wonder if i was going to be able to machine this 'backyard' piece. apparently home poured ally is very difficult to machine as its very soft and it clogs up the bit. so far i think its great !
just need to add some HTH to my next pour to degas it
So finally got round to trying out a one way flight using two transmitters ...
It didnt work out as there were too many 'other' things that went wrong , and by the time we were ready to go the wind was against us and the battery was quite empty already . Next time
At long last, first foam cut is done , and im very excited to do some proper shapes now
I did a quick pod and wing saddle model to try out the router ... its just a very simple model just to try and get my head around the whole toolpaths etc
Click on the pic for the result
Wow , soo many things have happened over the past few months , am employed now so dont have the free time that i used to :D but thats a good thing
Okay , first update is prolly my CNC router ... its taken a few months to build and will take a few months more to finish it
Click the pic for a few pics on the build
Have done my first cut , and i gotta say its WOW , very happy with it so far
This is about 60mm in height, 3mm cutter was used
Another new PC , the phenom didnt last long , but now got an 8 core number cruncher ... works great with the demands of 3d moddeling , just need to learn how to do that now :D
Models, so we have bought a few skywalkers to mess about with, do the whole formation flying thing, test out gear etc , i gotta say its a great plane to use as a beginner fpv model .... ive got a v/bagged 2.4 meter wing on mine with barn door flaps, it can descend like a hawk going for the kill . It doesnt have the efficeincy of a flying wing though, its more like a brick .... a lead brick .... imo ofcourse
What an exciting past week , i managed to do some demo flights at a local game reserve to gauge interest on the new plane.
Its a bit sensitive at the momement so i wont go into too much detail , but the interest is there and hopefully i will be in the position to fund further development on the aircraft.
Flying in front of 30+ people is great fun ! haha not! , but seriously it went very well except for landing in a cross wind and nosing over knocking the camera's out, no damage fortunately.
I look forward to flying an actuall objective , a fence patrol , road run , etc rather than just flying about aimlessly , and with no distractions so i can actually concentrate on what im actually looking at.
So ive been a little quite over the past few weeks .. its all due to my new project 'the anti-poacher'
Click on the pic for a few build pics
Still lots of work to do, im not crazy about the V tail , so am looking at changing it to either crusifix or to T tail. The RVOSD doesnt support V tail mixing so to get around this a seperate mixer is required but the resolution on the mixer isnt great. Also , dutch roll is quite apparent when applying rudder , more testing required
Sheeesh , no pc for over a month !! replaced the graphics card only to have summing else blow ... so decided it was time for an upgrade , AMD Phenom yes please !
Anyways, a few weeks back, we did a few range tests , 63kms on the Dragon link and 42kms on the 1w lawmate @1280mhz and the picture was pretty perfect, slight drop out on polarization mismatch but nothing serious.
this was the dragon link range test, Alex (in the picture) on the phone to me and Vaughan taking the pic ... i was sitting on my balcony in Jeffrey bay 60+kms away and we had a bind and full control.
This is a vid that Vaughan took a couple weeks later, the idea was for me to fly normal FPV at a field close to my house and for Vaughan to try intercept my video signal while he was 40+km's away , the video pretty much speaks for itself !
Other than that i been working flat out on my new project , 'the Poacher'
Pictures coming soon
Wow , i cant believe a week has gone by so fast, my dads red dragon flew ... but not very well
On launch it shot straight up but pulled quite bad to the left , after flying around for a few mins at half throttle i got it trimmed out, it needed ALOT of right trim to keep it straight and level. The feel of the plane wasnt great, summing didnt feel nice about it, admittedly i was flying without wingtips , but still summing wasnt quite right.
As i approached for landing all hell broke loose as the plane dropped a wing as it slowed down, what the ? i powered up and instantly it straightened itself out like nothing had happened ....
pass number two and the exact same thing again, as i started to slow down the left hand wing would start to drop to a point were i couldnt give enough right elevon to keep it level, so had to power up again....
after pass number 4 or 5 i got her down safely ... walking over to the aircraft i could see i must have had 3-4 millemeters of trim on either wing , WOW i thought , summing really not right here
onto a few more flights and still not sure why it was flying so bad, moved the CG forward to try again, but then due to a pathetic throw i cracked the spar and called it a day
BUT TODAY WE HAVE A WINNER !!!!!!
Yup just got back from a flight and she is purring like any red dragon would with a few heartburn pills , she has been tamed to a docile slow flyer , the changes and the faults .......
after inspecting the wing twist (which i thought i got the wrong way, i thought i molded in 'washin' instead of 'washout') it showed a huge flaw , the one wing had about 12mm more washout than the other ? how could this have happened i thought ? and how could i fix it ? after a few Google searches i found that this is a common problem with 'green' or newly made fibreglass parts. All i can think is that i had the wing lying against the wall and the weight over the past few days twisted it.
So to fix it, i added a 2kg weight on the wing root trailing edge, and a 1kg weight on the opposite wingtip leading edge laying on a flat table, over night it straightened out and is within 1mm of he other wing.
The next big change was dehidral , i added in about 40mm of dehidral to the wing , this was alot easier than i thought it would be to do. The pic below pretty much explains it all. You MUST wrap the joiner tube with aramid (kevlar) or it will simply split open and the wing will fold.
After writing off my dads old big wing uavr , we built another, this time we watched the weight. (spektrum lockout, we think , thats what you get from park flyer receivers, oops)
The span is a touch under 1.8 meters and weighs in at 2kgs ready to fly with a 6s 3.3A pack , no FPV gear yet
The previous wing had immense thrust with the 12x8 folding prop and deffinately the way to go with heavier setups , it climbs straight out your hands. Other changes include a slight decrease in wing sweep , but the same wing root/tip size as the original. Amazingly the CG stays in the exact same place according to my wing calculator.
Really am hoping to get it maidened this week, if the weather allows
Did a few range tests over the weekend, 26kms out i had a friend (Charl) connect up my plane while i was on my dads balcony back in Jeffreys bay, the weather was great and LOS was straight as i could see him through my telescope flashing a mirror in the sunlight ........
the video screen light blinked waiting for a signal ... a few seconds later it went solid and a fuzzy but ok'ish picture showed on the screen .. hmpft i was hoping for better. Tiliting the plane from side to side caused the video to drop completely, the mismatch in polarization was to great over that distance. 'oh well' i thought walking over to my yagi , that must be the limit.....
clicked on the diversity and my dad yells 'its crystal clear" ... i dunno why the diversity didnt click over, i think i need to make sure its set into diversity mode each time i use it. so that was 26kms on my patch antennae , wow ! with the yagi the signal was clear and had no problems with tiliting the plane thru to inverted.
however, the dragon link wasnt too happy though, as the plane passed 45 degrees failsafe kicked in, i really thought it would be fine as the last time i tested the dragon to 42kms, but never tried tilting the antennae .... hmmm yagi for the dragon, or a 7w booster ?
Had an awesome days flying yesterday and i gotta say im pretty impressed with the RVOSD so far (v5) Set it all up on a polystyrene foam wing and hit the field. The first flight was great, the plane launched easily and tracked great with correx wingtips. I flicked over into fly by wire and the plane immediately straightened itself out and flew like it was on rails ... with FBW you can still control the aircraft but it dampens out your inputs (adjustable) so that if you want to do a right hand turn you can give FULL right and the plane will only turn to a set banking degree and stay there, it will not go any further. Releasing full right and the aircraft returns to straight and level flight, i didnt however calibrate it 100% so i had a little left hand drift, but i think this is an easy fix
Next flight , just about to take off and the motor wouldnt spin up, the esc got wet from the previous flight landing in long wet grass...
Later in the afternoon we went out again .. my dad had two 20-25 minute flights and i showed him how the RTH and the FBW fuction worked ..
While banking hard , i would click FBW and the wing would level out immediately, so i thought i would try catch it out ... i went into a 90 degree climb and hit the FBW and again straight ... a 90 degree dive , yip straight ... inverted ! yip straight ! i think what impressed me was the speed that it got the wing into level flight, it seemed instant
Changing into return to home function is very easy in the menu , and to engage it i use right hand rudder stick, as a wing doesnt have a rudder
so we flew out 700-800 meters and engaged RTH , i was ready for the aircraft to go into a spiral , but ... it slowly did a turn , about 50 - 70 meters ish diameter and came straight back to us .. impressed !
so now with the wing going over our heads we both asked .. "whats it going to do now ?" as we watched it fly over and start to bank again into a 50m -70m diameter circle it loitered above us ..
Had a few hiccups on the way, video signal went really poor and decided to turn back at about 6kms , but after moving the antennae the signal came back squeeky clean so decided to turn around again and carry on heading out. Then again on the return trip about 3 kms out my video screen died, fortunately i had the goggles or the plane would have gone down
Aaarg im sick, caught a cold but i think im thru the thick of it, well hope so anyway.
The launch ramp is done, but now that i know what the cause of the random bad launches is i dont think it will need to use it. I will though ! I would like to stick a13.2A pack in the plane and see what it flies like with a heavy pack, obviously faster but how much faster and how much faster will the stall speed increase by ?
we will soon find out ;-)
I have taken out my Vtx camera and have decided to try use the Gopro as the Vtx camera , so far so good , had to change quite a few settings as the camera auto switches off after a given time, it also turned off once the SD card was full, NOT GOOD !
I am getting noise on the osd screen, but i think i can easily fix that with a filter (tarroid and capacitor)
Eagle tree telemetry is now working so i can plot live on google earth the flight , this should help for when getting lost :D just took a walk around the house and you can see how it plots the course.
Wahoo , i have found out whats causing my so called torque roll , its not torque roll but rather a poor setup
The transmitter for the video Vtx is mounted on the very tip of the right hand wing. this causes the aircraft to pull to the right, so to solve that i would just add left trim once in flight .. but ! this is the cause of the hard left roll that i get when launching , stupid left trim ! i did have a counter weight on the wingtip but took it off cause i thought it was making that side too heavy
next flight will prove if my theory is right
but a bungee launch is in the making, so maybe no more throwing will be required
Had a awesome flight today, i gotta admit i was pretty nervous with the launch as i wasnt sure how it was going to take off , would it pitch to the left like it randomly would ? would the torque at half throttle be too much ?
after posting my torque roll problem on RCgroups i had some great tips on getting her to launch
the most obvious , right hand trim ! duh
second , mix in ailerons onto rudder stick so i could feed in right hand rudder while launching
launch to the right of head on wind
smaller prop = less torque
well , she launched great .. too much right hand trim, but i was happy to see that it worked ! getting the trim back to where it should have been was a mission fumbling on the TX trying to find the trim slider , i know the feel of my DX7 but the FF8 is still a bit alien to me, but with time ill get used to it
No damage , 'cept for a cracked spar , oh well ...
After driving around for almost 2 hours looking for somewhere to fly we stopped outside this farm and thought lets give it a go. The farmer said 'video of this farm ? huh ? erm... yea sure go for it' so with his permission we had a great flight .. ill take him a copy so he can understand what we were on about ;-)
Things i found out, sunlight, what a difference when the sunshine comes thru. The massive sprinkler couldnt be seen when the sun was behind the clouds on the osd video , all i could see were the wheels and a very feint scaffolding outlines of the sprinkler. The moment the sun came out the whole construction lit up
6kms ! my furtherest flight yet , and it was easy ! could easily have done double the distance if i had both my battery packs on
This foam wing is soo much better than my last one, having a proper high lift airfoil thats designed for use in flying wings has made such a difference , i cant wait till i have a glass wing , its going to be so much better.