FT Swappable Trainer Build

by snuffy | February 24, 2014 | (8) Posted in Projects

My Trainer Build (FT Swappable Trainer design by smit6089)

This my first ever attempt at an RC plane; I'm just starting out and wanted to build something I wouldn't cry over when crashing it. It weighs in at 639g (flying weight), not sure if that's heavy or not; it's made from the UK foam board from HobbyCraft.

I've not flown it yet, but any day now, weather dependant! I also made a Versa Wing and will create an article for that too

The finished thing:

Two wings: Dihedral (top), and flat with ailerons (bottom)

I would buy slightly bigger guage than 18 next time; it's a bit too bendy!

 

A scalpul/Exacto-Knife makes all the difference!

 

I've also built a Versa Wing (flown neither of them yet!)

Dihedral wing

Flat wing, with ailerons (and programmed as flapperons!)

Wire strengthening for elevator:

Power Pod fitted:

I made a 12V power supply for my Turnigy Accucel 6 out of an old PC power supply:

I bought control horns, but in hindsight would use popsicle sticks (or the Flite-test ply horns) in future; way easier to use and structurally more sound.

Yep, only after I put the red tape on did I remember that port is on the left! Doh!

 

 

 

9XR with OpenTX, Turnigy 2200 battery, Hobbyking 30A UBEC, Turnigy NTM 2826 1100KV motor, FrSky X8R and matching module:

Prop balanced with tape. Notice the change in motor. The NTM had the prop shaft out of the wrong end, so I couldn't fit a prop saver, so I got this Turnigy D2826-10 1400kv motor, balanced with a bit of black electrical tape as you can see. I balanced it with the zip tie method.

- Find this article & others like it at www.FliteTest.com -

Related Articles

Swappable Trainer Build Plans and Videos

by smit6089

COMMENTS

MyAKAndI on March 27, 2014
Awesome! I built this trainer as well, but the weather hasn't permitted me to take it out for a maiden :L
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snuffy on March 28, 2014
I've only flown it once; surprised it flew as well as it did as it seems really heavy with a 2200 battery. I then yanked a turn too tight and fell out of the sky. It's all hot-glued back together and all good to go again.
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alibopo on March 28, 2014
Snickers cruelly... :) yep, it's a bit like painting the name of a boat up-sides-down because it was sitting keel up when you did the lettering. The way I remember port & starboard is with these two little phrases;

PORT wine is RED & There's no PORT LEFT in the bottle PORT-RED-LEFT

Apparently sailors are famous for drinking Port wine!

The only possible negative I can see with the design is the tail-steering. All the landing forces transmit through the tail wheel and into the rudder's paper hinge (though I do see a clear tape reinforcement on your build). I'd be interested to hear how others have found this working over time? Has it been strong enough or has the rudder hinge needed patching? Also balance - does it need a lot of extra nose weight to balance out the wheel and wire assembly stuck on the tail? It's got a good length of nose, so it's probably fine - but I'm curious to know.

I don't know where you are with your flying skills, so please don't be offended if I mention I don't see any side or down thrust on the motor mount. Can I suggest dialling-in a touch of right rudder, and/or a couple of clicks of right-roll on the ailerons to help compensate for torque roll when you go for the maiden.

It's a nice build though, I'm looking forward to seeing some flight footage. There was none in the original build article you linked to, though lots of people sang its praises, but I always like to see a plane in flight to get a good idea how it performs. Cheers.
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alibopo on March 28, 2014
Ahah! - Just spotted the link to the flight. Seems to fly well enough, quite fast, but it was hard to tell what its characteristics were with it being so far away most of the time. Anyone else got flight footage?
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snuffy on March 28, 2014
Think that video would be the original designers video. I'll aim to get the GF to take some video when I get out again.
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snuffy on March 28, 2014
Yep that's how I remember it too; my dad taught me years ago.

I'm not sure how well the tail will hold up, however I put plenty of tape on so should be ok for a while, and if it fails I'll just tape it again.

Balance was fine, the 2200 battery was well up into the nose, about 1.5 inches from the firewall so a little room for adjustment.

Not offended at all; I'm abysmal. Have about 5 hrs or so on RC Desk Pilot so orientation is fine, but I'm all left, or all right, or all up, or all down at the moment... need to dial back my thumbs. I managed to keep my Versa Wing in the air (mostly), have a total of about 10 mins on that thing, and 2 minutes on this one. I have dialed in a bit of right and down on the transmitter and it flew level and straight (until I smashed it into the ground). I also saw photos of how someone had built that into the powerpod by modifying the angles on the power pod, so next build I'll do that I think.

I have yet to see what effect the 3 flapperon settings have to flight... maybe tomorrow, UK weather permitting.
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alibopo on March 28, 2014
Hah! Best of luck with the weather - nothing but wind forecast for the next week here in Scotland. And a brave man too, taking on ailerons. All my early flying was with 3 channel planes; the Old Fogey andr the FT Flyer, which is a wonderful little plane. One of my planes has a pretty similar wing chord and wingspan to your build - it's based on the Pilatus Porter. Sadly I've never managed to keep it in the air long enough to get it trimmed out - it's just too squirrelly in the air for me. I've had much more success with deeper chord wings. I reckon if you're aiming for a 'magic' figure, say 25% of chord, it's less likely to be wrong if the chord is larger. To my way of thinking, a narrower wing equals a smaller target area, and less wiggle room if your first guesstimate is a bit out. If you struggle to keep this critter in the air, you might consider making up another wing with a longer chord - there's plenty of flat surface on the top of the fuselage to play with. Increased wing area would also give you a slower, more manageable flying experience. Personally I'm all for slow and manageable! Cheers.
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NoUsername on March 28, 2014
Really love your build for the stearable tail wheel!
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snuffy on March 29, 2014
I can't claim that design I'm afraid, it's by smit6089. :-)
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Greg1516 on March 29, 2014
You can also remember port and starboard by the number of letters in the words. Left has four letters same as port. Starboard and right have more letters to spell them than port and left.
Little word left, bigger word right. I came up with this when I was a young Marine recruit at Paris Island.I remember the DI shouting "Port side shower up..starboard side shine 'em up". Since they don't shine boots anymore, I guess that is a thing of the past.
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snuffy on March 30, 2014
Flew this morning... after 4 crashes, each within about 5 seconds of being in the air got it up and flew for 4 minutes, before losing control and flew it into a tree; it made a helluva crack as it hit the branches. Luckily there was a big long branch lying on the floor near the tree so managed to poke it out of the tree.

Damage: fuselage bent and torn, elevator torn, rudder bent pretty badly (easily hotglued back together), propeller snapped, and worst of all I snapped off one of the antennas from my FrSky X8R receiver! Not sure whether to get a replacement, or just go with a new OrangeRX module and receiver; might be more cost effective in the long run if I keep breaking them!?
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alibopo on March 31, 2014
Hi, just spotted your woes! Have a good look at repairs for the receiver on youtube. Apparently the antennae on most of these2.4ghz units can be re-attached/soldered quite easily. A quick range check will confirm a good-enough repair. Regarding OrangeRX, I'm a convert, but I use a Spektrum DX6i as my transmitter - which I picked up cheap from Ebay because it had a broken switch :) I buy my OrangeRx receivers through HobbyKing from China - cheaper prices and also cheaper postage than going to their UK store if the weights are low! OK there's a delay, but I've never lost anything in transit. Regarding the foam repairs - just go for it - I'm surprised how little difference the odd deformity makes. Where you see a strong pressure fold where the paper has a line in it, run a craft knife down the line of deformation, open up the foam board and run a bead of hot glue down the crack. Scrape off excess glue and hold the panel until it resets in its original (or near enough original) shape. I've repaired buckled ailerons, wingtips and the fuselage with this method, and the foam board seems to get back most if not all of its strength and rigidity. Might not look great, but it does the job!
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snuffy on April 2, 2014
Yep, if I still had it... lost it in the crash and didn't realise until I got home. Needle in haystack, so will try to get replacement antennae I think. Not sure about the requirements on these with regards to length, diameter etc. so will need to do some research. I also get my stuff from the China Hobbyking warehouse. Hadn't thought about the pressure cracks idea before; I'll try that, thanks.
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alibopo on April 2, 2014
If you've still got one antennae, you've got the length (or 31.25mm if you want to be fussy). Lots of good youtube tutorials on exactly this type of repair. Cheers.
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snuffy on April 3, 2014
I have found the relevant antennae replacements on Hobbyking so I'll order them and solder them on. Thanks for your help :-)
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snuffy on April 28, 2014
Yeah, so I received the new antennae... the coax antenna wire is TINY!! I carefully (with a scalpul and steady hands) bared back the outer braided section, (could have done with a magnifying glass!) and plastic insulator and soldered on... but in the end it didn't work. I bought a FrSky V8FR-II for £20 to replace it. I can see that this one has the pop on connector type so will be a piece of cake to replace if I do it again! I'm back ready to fly once this miserable weather abates.
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alexwhowhat on April 7, 2014
Please can you make a video on how you made your power supply from an old PC PSU?
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snuffy on April 7, 2014
Hi, if you do a quick youtube/google search you'll find loads and loads of videos/howto articles. Essentially you chop off all the plugs you don't need and shrink tube/tape up the ends, leaving just one of the black/yellow ones (the 12V ones) to power your battery charger. Then there are two of the wires that you connect together (the PC case on/off button) so that the power supply stays on constantly without requiring an on/off button. Can't remember the colours of those but they're well documented online... think one was green? Use a multimeter to make sure you don't cock it up, and use your common sense with electricity. ;-)
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jburchel on April 27, 2014
Where is the CG? I don't have a 2200, will be using something a little smaller... just wondered if you had found and could tell us where center of gravity is... I have it built... waiting to maiden until I know where to put battery. Thanks
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snuffy on April 28, 2014
Hi, I just put the battery in and make sure that when I put a finger under the fattest section of each wing and lift it up it balances level or slightly nose down. If it's not, I move the battery around. Maybe I'm doing it wrong, so let me know! I have found that going fast is good with this plane; until you get the hang of it; if you go too slow it tends to drop a wing. I've only flown a couple of times so far with it, so let me know if you get any video of it, it would be good to get any tips. Good luck!
Tim.
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DukeNukem on June 24, 2014
HA i use a 650 wtt thremaltech psu myself . Thats funny. Works great, couple different volts, runn some led work lights.
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FT Swappable Trainer Build