Você está no 3DFinder
Buscamos em Thingiverse, MakerWorld e Printables ao mesmo tempo para te dar o melhor de cada uma.
Descrição
Safely launch any (fpv) model airplane up to 5kg AUW with ease and 100% success !
Especially FPV pusher prop planes like the Funjet, Mini Drak, AR Wing Pro or the upcoming Mojito need a sophisticated launch technique to successfully get them airborne. INAV auto-launch helps a lot, but cannot deal with any user-induced launch mishap. Things get even harder the heavier the build and/or the more the drivetrain is propped for speed.
Most common launch techniques and their downsides:
Side-launch: needs to be trained. Tends to either induce a spin or a roll input into the plane. Uncomfortable for heavier planes 2kg AUW and up. Uncomfortable with wingspans 1 metre and up
Double-handed overhead launch: most uncomfortable launch. Tends to induce too much upwards pitch into the plane. Weakest launch speed. Prop may cut your face. Plane can only be launched with radio on the ground or by a second person
Discus lauch: most powerful toolless hand launch. Spin input similar to side launch, throwing peg in the wingtip required, AUWs of 1kg and up need heavy reinforcements in the wings and especially the wing joiners or it will rip the plane apart
Paperplane launch: go-to launch for tractor planes. Pusher plane props will chop your hands
Bungee launch: 100% success rate when done properly. Needs space and a proper ground anchor. If the rubber snaps or the ground anchor comes loose you have a potentially lethal catapult projectile coming directly at your face.
Enter the GrumpyStick: It is a combination of the principles of a pre-historc one-handed spear thrower (atlatl), a ball thrower for dogs and a fishing rod.
It uses leverage to achieve greater velocity in throwing to be able to launch planes with high wingload or high pitch props with lesser low end thrust.
It keeps your hands and face safely away from spinning propellers and lets you face into the launch direction.
It releases the plane in between 2.5 and 3m height ( two handed operation ) and up to three times faster than normal throwing speeds
It lets you precisely control the launch vector and does not induce spin or roll momentum
It does not need to be set up and uses very little space in your backpack
Can be used for self defense against entitled bystanders ;)
Feel free to use the concept and add variety. If you cut the tube to 20cm, you have a very handy tool to launch lighter planes one-handed. You might want to experiment with the sleeve position holding the fingers to adapt to different fuselage types. You might even try and design your own sleeves for different planes.
Happy flying !
Assembly:
Print rather slow and with a generous amount of material. Sleeve with fingers HAS to be TPU, bottom plug should be, for the rest you might get away with other stuff.
Assembly should be self explanatory, you only need a 16x14x1000mm carbon tube, paracord and a 3mm scrap carbon rod or anything else that might do the job. A nail probably.
Place the TPU handle on the ground and gently push the tube into it until you reach the floor. Push the sleeve on top of the tube and adjust its position so that the fingers will firmly push the fuselage of your plane. Mine are so close to the fuse they actually bend to the rear of the plane to help with positioning.
Put the top plug in and route the paracord through both holes. The middle section will prevent it from falling in
Put a broom stick or a hammer handle below the bottom of the TPU handle and tie the paracord around it with a tight square knot. Square knots are easy to do and easy to adjust. Pull out the broom stick or hammer. Hide the knot inside the tube by pulling one side of the paracord. Route the paracord through the bottom plug and secure it with the carbon rod. 3mm carbon rods are held in place by the TPU, no glue needed. Pull out the loop on top. Done. You should now have just the right amount of cord for easy use.
Positioning the launch hook:
The launch hook I included is just an example and only recommendable for planes up to and around 1000g/2lbs. It might be just ripped out of the foam of heavier planes. Adjust accordingly, even consider anchoring the hook with a plate on the inside of the plane. The hook should be well in front of the CG. There is quite a lot of literature around bungee launching planes and launch hook positioning, you want to place the hook a tad more aft than recommended. Experiment yourself.
Hook should be designed for easy release, otherwise you might pull the plane down instead of releasing it. A small key ring on the rope might help with that. Feel free to post your findings in the comments.
Use:
Hang your plane into the loop so that it can be easily controlled with the two fingers. The fingers help you to hold the plane steady even in gusts. Adjust if needed. The FF term, at least in INAV, will now try to compensate by moving the control surfaces down. This is irrelevant and no I-Term windup. It will be completely fine and not mess with your launch.
Now picture a fishing rod and perform the exact same motion. The motion should be circular, fluent and powerful and you want to stop the motion just after you reached the zenith at around 130°. If you pull through you might pull the plane's nose down again. The launch settings I posted in the pictures will gently spin up the prop after release to prevent prop strikes on the tube. An average grown up male can expect around 60 kph/37mph launch speed with a one meter/3ft tube and 2kg/4lbs AUW with ease, therefore the plane will have enough airspeed to counter torque roll.
Variations:
- experiment with various tube lengths for one- or two-handed operation or different AUW's
- experiment with different shapes of the finger sleeve
- experiment with different launch hook shapes, rings or sleeves around the paracord ( a PTFE filament tube maybe ? )
- experiment with different tubes or sticks. One of my friends and early adopters will use a broom stick for launching his Daddy Drak ;)
A little illustration how it works in the video. I will update as soon as I am allowed to show the plane this was actually designed for
assembly as follows: (Yes, I will publish a properly edited one with less nonsense ;) )
