My X8 launcher

[Coyote]

Hi guys, just a quick thread for my X8 bungee launcher.................

I got motivated thanks to Skipperbilly and a few failed attempt at launching last weekend due to lack of airspeed mixed with torque roll s decided I better make a launcher and save a whole world o pain :)

I made it from :

4x 32mm solvent type drain pipe
4x 32mm solvent type elbows
4x 32mm solvent type T`s

2m length 3x1 PSE wood
Pack of ten M5 x 50mm bolts
Pack of ten M5 Nylon nuts
6x 100mm x 10mm bolts ( for staking launcher to the ground )
T brackets from B&Q
3x 6" nails
4x Keyring rings

2x 10m length on 10mm ( blue ) Silicon Bungee tube
14.6m Nylon rope
Pets at Home dog screw in dog stake
Digital luggage scales 

I dry fitted the launcher first to gauge the angle I wanted, you can see below how basic the design is, I used T`s for each corner for added stabability. Elbows on the top with the front two elbows cut down and glued in place so the wings do not catch on the launch



I experimented with the width with the X8 on until I was happy with how it sat, how it was supported and a natural travel up the ramp



Once I was happy I cut the legs down to a more practical height and the shorter length makes the legs stiffer too



Next I added the trigger for the bungee release, very simple I was after.

It comprises of two T brackets bolted to either side of the pipe, a bolt locked from the inside and outside of the brackets to strengthen and keep the gap for the wood constant. I drilled a cut piece of the 3x1 and it will pivot on the bracket.

A 6" nail will be what holds the ring in place, curved backwards so it wont accidentally fall off. The wood when pressed down on will raise, push the ring over the nail and release the plane.

I added rubber bands to hold the wood down so it can not be accidentally triggered. It also keeps the wood square when using it.





The bungee tube should arrive tomorrow, so until then all I could do was make up the nylon end.

One ring, the release ring go to the trigger, the second rig goes to the plane. Both rings were connected to the rope by using fishing knots. I used the tucked blood knot, works very well.



Very neat knot, which I left a tail hanging from, the heatshrink ed the tail to neaten it up a bit more as above.

To connect the two lines to each other I used the 5 turn water knot, again very strong but with rope, also very neat too



The idea being that with both hooks on, both the release ring and the plane ring will both be under tension so no nasty shock load goes to the plane when I trigger the release. It was pretty easy to do by using the water knot.

So the plane end looks like this :



Ill update with bungee end when it turns up, then either some awesome or totally hilarious launch videos :)

[Flyn]

Really nice build mate, should be a good one. Cant wait to see your 1st launch.

[bignose13]

Nice piece of engineering mate, look forward to the test vids

[Dizzy]

hope you pressure tested it coyote,  those joints look a bit sus to me, what with all the regs these days, do i see knicker elastic or what there ;D
0 to 60 in 0.5 secs :o looking brill  :)
dizzy ;)

[pk-surfing]

Nice launcher, that's going to work like a dream...... hardly seems worth doing a video of the first launches  :D

Hope the bungee arrives soon !

[Zeeflyboy]

Nice. Looking forward to seeing this one in action!

[Skipper Billy]

@Coyote

If you PM me your address I will post you two stainless steel welded rings (FOC) - those key ring type split rings will open up with 12 kgs of pull and the bungee will do its best to castrate you - it doesn't matter how I know but I am typing in a high pitched voice!

[Coyote]

Lol thanks Billy, I will do.

I went to Boyes today to find some more heavier duty ones but no joy.

[Coyote]

Ok.............. bungee tube came today :)

I came up with my own version of making the ends off of the bungee tube. So far 1 tried, I pulled and pulled and it would not come away

I got some Wilko screw eyes, very strong.



The bungee of course, then I sized up some prop shaft adapter rings

I put the rings on the tube, 2 per piece, then glue on the shaft of the screw eye.



Screwed it in, slid the rings up so the rubber was very tight against the shaft

I let it dry and then pulled as hard as I could. So far a pass, but when the scales turn up I can properly test under load :)



I think using carabenas between the ings might be an idea.

Also I noticed the plane has quite high friction against the ramp. Not too clever, the poly tunnel tape does not like it. But with the wings off I could hardly keep the fuse on the ramp, the carbon rods were acting like the ramp was oiled :)

Next mod, to install some short carbon rods on the underside of the wings to keep the pull required down :) 

[Coyote]

Thanks for the comments lads n lasses :)

I forgot to put a pic up of the ground screw I`m using to hold the far end of the bungee in :



Ok, a bit changed, first big thanks to Skipper Billy for sending me up two steel welded rings. Much much stronger than my keyring efforts and as I have now found out essential really.

Next thanks goes to Shay :) Shay is one of the two children Donna and I have in our care. Why ? Because I hunted high n low for a parachute for the bungee cord. Apart from paying 20 quid for one online I was out of options. Shay came down with his action man, said " you can have his parachute " and " I don`t like him anyway " lol  Never been so happy to buy the child a toy he didnt like lol



There is the result with new rings and chute :)

Ok so today its pouring down, didnt want to take to X8 out on a soaking wet muddy field, but initial launcher / bungee tests ? Hell yeah :)

First attempt did not go well to be honest. One of the glued eyed bolts didnt stay on, all I heard as I was walking away was a weird sort of buzz notice, then followed the bungee ( minus the bolt ) wrapped me across the back of my leg and finger ........................... Then followed ( in this order ) pain, jumping, profanity, screaming and then calm :)

I packed up, went back, swapped out the eyed bolts for just knots and went for round two ...................

Round two went great, I wanted to prove :

Bungee was fine at 15kg of load ( I only need 12kg max )
Fixing on the cord held
Pets at home dog spike held at 15kg
Launcher trigger could hold 15kg load
Launcher stayed in place under load
Release mechanism worked
Parachute worked
How many paces needed for required load

All the above completed including sat in the car for 20 mins with bungee on the launcher at 15kg to make sure nothing would come away if it was left for any time :)

so far I think ( if my scales are correct ) that 12kg is way too much load needed to launch the X8, Ill start at 9KG of pull tomorrow and I bet that has more than enough tbh 

[g.collins]

Looking good Ian, love the corkscrew, I don't think you should drink and fly tho.
:laugh: G

[Coyote]

 :pint: Lol cheers G

[FPVSteve]

Put a tin of beans next to it for scale heh

[Coyote]

I dunno, some people are never happy :)



Better ? :)

[FPVSteve]

I was on about the corkscrew, G man reckons you're gonna open a bottle of wine - some bottle of wine!!!!