Experimental Airlines Photon build (4/5th scale)


Elite member
I did some experimenting with where I can put the battery and receiver to make it balance. If I put them here, it balances round about on the spar (maybe slightly forward).
View attachment 236505
That's about as far back as I can get this battery with this hatch. I'm considering making some sort of tray so the battery can be velcroed to that, and then the tray can velcro to the fuse. That way I can get the battery further down inside the plane and still get it in and out! I'm not sure the hatch is big enough to do that and get the tray and the battery in at the same time, (and there's not really enough space for a sliding tray). I had similar battery placement issues with the last foamboard -> depron build I did (flite test mini scout) - think I need to learn my lesson and make the tail from something a bit more heavy duty next time!
Hey Duncan, are you on the ARCN discord server? seen your name here and there.


I did the work in the previous post a few days ago, but failed to press Post!
Yesterday I made some more progress - I put a hatch in the tail for the receiver, re-inforced it with a gift card and a couple of lolly sticks and ran all the extension cables I needed so as everything would reach the receiver. Then I put a battery in again and balanced it. The balance point is where the dots on the wings are - I think that's around about where the spar is:
Hopefully that's OK,I don't think I can get anything more moved backwards, so if it doesn't work I might have to put some pennies under the tail! You can just about see the hatch where the receiver ears are poking out in this picture. I've only ever used receivers with the plain wires before - do I need to poke these ears outside the fuse or can I leave them tucked up inside? If I have to poke them out, I'll make special holes for them, but that will mean moving the receiver to plug stuff in will be a pain.

I also ran the wires back to the front hatch so I can plug in the telemetry sensor for the battery voltage. It's a bit tight in that front hatch, and the sensor and the speed controller get in the way of putting the battery in, but it all just fits, and the hatch hole looks really empty when everything's in because the battery is so far back! I'll have to take a picture today. Final picture of everything put together:

I'm gonna plug the ailerons n and make sure they operate the right way around today, and then I'm considering trying a glide test. I'm somewhat concerned I'll just break it, which would be enormously sad! It's the wrong time of year for long grass, but at least the ground is soft at the moment (just don't land it in a puddle!).


Good news - I threw it and didn't break it! )
It even sort of glided, though the battery moved forward after the first nose heavy landing, so the ones I got on video aren't as good. I think the roll to the left is the way I threw it. Hopefully, if it was under power, then it would climb. :)
The nose is a little creased but held up fine. however, the bit just behind the wing supports is clearly weaker than the rest of the fuse (it has 2 big holes in it) and has a big stress riser of the wings, and so it's way too flexible there now. This picture is with the back on the bench and the nose lifted slightly, but you can see the creases in the side and where it folded a little.

I clearly needs reinforcing before I can fly it - the question is how. Ideally I'd like to put something like bamboo squewers or lolly sticks inside the fuse, but that would mean cutting a hole so as I could gain access. I could just stick something on the top - it's where the wings are so I'd have to put that at the front too, but that could give a nice sturdy wing connection point. It's not the most aerodynamically important part, so I'm not too bothered about putting something on the outside, I just want it to be tough. I'd probably put half an ID card on each side as well then, to stop the creased sides from being a weak point.


After a certain amount of thought, I figured the foam that's there already isn't doing much given how it crumples. So I cut the section out, which gave me access to the inside.

I then hot glued 3 lolly sticks inside on the base (I was going to do 4 but one ended up a bit wonky, so there wasn't space for 4). One on each side towards the bottom, so it didn't interfere with the cutouts, and then 2 somewhat cut-down ones on the top (had to cut them down so I could slot them through the holes). I used hot glue because it sets fast enough I could just press it in place with my fingers - I've used gorilla glue on this plane everywhere I could use a clamp.

This seemed pretty sturdy, so I prettied it up with a small piece of foam glued on top of those sticks and to the existing foam at each end, and then taped over the join.

I think this plane is now in the right place for a maiden, but I'm still on the buddy box, and I've got a couple of other planes (both bought) ahead of this in the queue to be maidened. Hopefully I can do one today, and then maybe this next week.


New member
Wow this looks really cool you have me looking at experimental airlines stuff now lol. i saw the jscott and ansly peace drone that looked cool i also found a black plane on here at some point that used those building techniques i just wasn't sure what they meant by ea techniques until now.


Master member
What a great build thread and plane. I'm sure it will fly fine. BTW, for best performance you want the holes in the control horns on the hinge lines of the movable surface. And yes, building fold-over wings so that each side has the same airfoil is a real challenge. I've made a few wings with a few 1/2 ribs glued in to help get the same airfoil on both sides.


Maidened this yesterday.
A club member who knows what they are doing trimmed it after throwing it with no power a couple of times, and then he flew it under power. The maiden was cut a bit short (and I don't have any video) because the horses that live on the meadow had decided we had a picnic and in the absence of food would see if they could eat planes, tools, bike saddles and anything else they could reach! The conclusion of the test flight was that it floated around the sky lovely when under minimal power, but it was enormously jittery with power.
When the horses finally gave up on eating our stuff and wandered off I got to fly it, and yes, it was great when flying with low throttle, and very erratic when I applied significant throttle. I kept it in front of me a while, but messed up and got it going downwind and quite low. Whenever I tried to climb to turn, the way it was under power spooked me, and I just set it down nice and gently (and thankfully missing a giant puddle). I've put a BBQ skewer in the elevator to see if that would help, but it's still a bit bowed, so I think the answer is probably to ditch this one and make a new one out of something more rigid (probably foamboard). That will change the CG a bit, but there's a huge amount of scope for moving the battery forward.
The only other thing I'm concerned about is the rigidity of the rear part of the fuse. It's pretty long, and while the box is OK at resisting twisting forces, a bending load will cause it issues. I'm considering re-inforcing it with carbon, but there's no space inside the fuse, so I may try it with arrow shafts on the outside.
I think when the kinks are ironed out it will fly nice and floaty, but I'm wondering if the best answer is to view this as a kind of 0.1 version, and aim towards a version with a carbon spar aft of the wing (and maybe a foamboard front section). I think that would allow me to keep the same wings, but have a stiffer, sturdier, more stable package (and offer the side benefit of separable fuse as well as folding wings).


I added a bamboo skewer into the existing elevator, but then I started poking around, and I realised that I can wiggle the motor around a little in the fuse! :oops: It's not loose on the mount, and the fuse isn't flexing, so I think that the mounting tape that is connecting the motor mount to the glued in ID card is probably flexing a little. My plan is to make a reinforcing mount that will attach to the top of the fuse and brace it a lot more, so it doesn't move, and then try flying it again.


I had a further evaluation and realised that the front of the structure was flexing, as well as the motor mount. So I chopped about 2 inches off the front, and I'm currently fixing a wooden firewall similar to the Flite Test style ones. I'll take a picture once it's no longer covered in masking tape. I'm kinda hoping this will move the CG a little further back, which will mean that I can move the battery a cm or so forwards - it would make it easier to fit it and fix it.
I also bought a piece of steel channel from the hardware store - it weighs about 280g for a 2m length, so I don't really want to use it, but if I need to beef up the fuse, I could fix it to the bottom. That would be about 60cm, so an extra 90g or so, much of which would be behind the CG, which would make moving the battery forwards something I could do (and maybe moving the receiver forwards too).


Minor update - I finished the firewall, which made a significant difference to the CG so I had to move the battery right into the hatch instead of under the wing. That's a big improvement for installing it and next time I work on it I'll add some extra restraint so the battery can't move. I tried to fly it last week, but the hand launch went squirrely and I crashed it - the front survived fine but the back of the fuse crumpled a bit so I had to add some more reinforcement back there. Hopefully it'll be good next time I get to fly it.
It doesn't look as cool as it did before, but hopefully it will fly better! Pictures as promised: