Fixed-wing UAV launch from car top

Hello everyone! 

For the past few months we were looking for a more convenient way to launch our PD-1 fixed-wing UAV (MTOW is 40 kg). Since runway takeoff and landing requires pretty serious and long training for the operator and any pneumatic launchers that will work with our UAV are expensive (from $30000 USD (actually we couldn't find anything less than $50k)) we decided to look for alternatives. Car top launch was one of those alternatives. We quickly developed a test unit and ran a few tests. So far we already have some statistics and pretty sure that it can be a good alternative to expensive pneumatic launchers in some civil applications with tight budget. Let me know your opinion on this. Do you think such way to launch a UAV could be an option? 

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    The advantage a catapult gives (freestanding or truck mounted ) is that it can be faced directly into the wind and the flight direction is already defined so that poles, trees and wires etc are not a problem. We launch directly under wires many times.

    The aircraft is already flying long before it leaves the catapult and the flight controls are fully functional. The autopilot can automatically start the motor as the aircraft leaves the catapult or the motor can run to assist the launch. both give a good and repeatable launch with a greatly reduced workload for the pilot. its safer and much more predictable. you also dont need a road!,

    The post is about using the vehicle as a moving launch platform to get the launch speed, for large aircraft this is less stressful for the aircraft than a catapult, you just need a smooth road or the stresses are too great. Horses for courses etc. 

    Also a catapult allows easy single handed operation, the van needs a driver as well as the aircraft pilot. 

  • Dwgsparky: Right, but all those problems apply to the kind of vehicle take-off described in this article, don't they? Cross-winds could still blow the drone into a pole before it got height enough after release, and overhead wires would still be a problem, right?

    Jacob Cereteli: If the operator still has to control everything, how can you call that automatic? I assumed there was some simple non-alignments fan beam system, battery-operated, that can be set behind the drone on a section of road without overhead wires. Then the drone would sense the laser from behind and adjust for cross-winds, gusts, etc until it got above the height of the fan which would, presumably, be above the height of any lateral obstructions. Such a thing doesn't exist?

    As you point out, landing is hard in any case, but, with a fan laser-aligment 'puck' sitting in the middle of the road, all the drone would have to do is us GPS to acquire the end of the fan at altitude and then use it to dead-stick in until contact is made with the road.

    This is, after all, what ILS does over a longer range, right?
  • Similar approach -

  • Sam, there is an automatic take off feature. It doesn't need anything. Operator still has to control anything and react to any situation changes, but in most cases UAV will take off with out operator touching the sticks. Landing on the other hand is a bit more complicated. You can check our YT video, especially PD-1 playlist, to see how it usually goes. 

  • Moderator

    road takeoffs are tricky because you usually have to set up and operate with other mobile vehicles and the inherent obstacles at the roadside such as telephone poles, trees and overhead wires, We solved this problem by using a truck mounted catapult to get accurately directed launches in a short time. We can simply stop at a convenient place, attach the aircraft to the prepared catapult and pull the release, if we preload the catapult we dont even need to get out of the truck!. set up time can be less than 30seconds. this is not suitable for the aircraft described in this post, its too heavy to use a short catapult. 

  • Was caught by your comment that a road take-off takes considerable training. Not being very knowledgeable in drones, I was rather surprised by that. Don't they make some sort of laser beacon which can be set on the roadway to guide the aircraft for an automatic take-off?

    (Align the beam with the road, use rear-facing sensors in the wing-tips to keep the drone within the beam until enough altitude is reached.)
  • Very cool!  Keep  the videos coming!  ;)

  • Hello everyone. Thanks for commenting. We do use Pixhawk for PD-1, however other autopilot option are also available. Reason for that is that quite often budget for such projects is very tight. Pixhawk work really great and we are currently working on fully automatic launch from car. Right now it is sort of assisted version. 

    Parachute landing works well. We have about ten landings with this particular parachute/landing bag (previously we were testing other shape of the parachute) and so far everything is good. Pixhawk allows to use all those amazing features like catapult/car top launch and parachute landing. As well as, for example, we can automatically start/restart the engine during the flight with on-board starter/generator. We will be posting more videos and materials soon. 

  • Moderator

    We have been building Catapults at www, for a long time now and your approach is good, 

    Catapults can work very well when they are designed correctly for the aircraft, 

    The big problem with larger aircraft is to get the aircraft to flying speed in the (relativity) short length of the catapult ramp without having to apply so much force that the aircraft is destroyed. 8-10G is common. 

    For aircraft over approx 25Kg then an electric version works much better as you can control the speed  (and so the thrust ) much more progressively and so cause less damage.

    I like your airbag for landing,great idea.  

  • Looks great Jacob, well done!. Car top launches can definitely   be a good  alternative to catapults. It's been used in a number of situations, for instance here with an Aerosonde in Antarctica by a research team from the University of Colorado and CIRES. (picture below from John Cassano)

    Looks like you've been using Ardupilot with the PD-1 (Saw your  "People's Drone PD 1 with gimbal test" video on YT,  also your groundstation with stab switch on UKRSPECSYSTEMS site).  So you could also easily go VTOL with a quadplane architecture as an alternative, with some flight time  reduction.

    Congrats btw on your products, very professional and all look amazing good!

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