• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Landing a Rocket Vertically, without Being a Billionaire

#1

Attachments

#2
This is a pretty cool idea. I would love to see a vid of it working. It's bound to add a lot of weight, and drag to your rocket. It is designed to put the motors at the center of gravity?

It's been awhile since I've built a water rocket, but I have one in the works at the moment. The last couple had parachute recovery, and the next one will be a retroglide recovery. You have inspired me to see if I can't make it an r/c retroglider. that would be pretty cool.
 
#3
This is a pretty cool idea. I would love to see a vid of it working. It's bound to add a lot of weight, and drag to your rocket. It is designed to put the motors at the center of gravity?

It's been awhile since I've built a water rocket, but I have one in the works at the moment. The last couple had parachute recovery, and the next one will be a retroglide recovery. You have inspired me to see if I can't make it an r/c retroglider. that would be pretty cool.
Here the links of the videos come...
https://youtu.be/JehjgXvUAzA
https://youtu.be/K073sd_vCu0

Spot on regarding the motors. They are places exactly at the CG of the Rocket (arms folded).
The Rocket Drone has been designed to swap easily the rocket modules, from water to pyro, therefore you can build/use both modules. Not mentioning all the fun there is in launching and landing vertically the rocket, the other good thing of the Rocket Drone is that has an ascending speed of 12 meter per second. If you need to deploy the drone straightaway, reaching the altitude wanted, this is exactly what it does.

Looking forward to seeing your retroglider.

Best,
G.
 
#5
That is so cool. Thanks for sharing it.

Good luck with the patent. What applications do you see for this? Of course it is great as a toy, but I wonder if you have other ideas in mind.
 
#7
That is so cool. Thanks for sharing it.

Good luck with the patent. What applications do you see for this? Of course it is great as a toy, but I wonder if you have other ideas in mind.
I'm sorry for the late reply, but I've just seen your post.
In my patent application I've tried to broad as much as possible the uses of the Rocket Drone. It could be deployed in Law Enforcement/Militaries scenarios (as a deterrent and for patrol/reconnaissance), or even as a Emergency Marine Rocket Flare.

I watched a video of a Company, specialized in military drones and I was quite surprised by the time taken to deploy the aircraft (in an emergency situation).

https://www.youtube.com/watch?v=DiTzO8oKWRU

I've thought also that the rocket flare used in case of emergency on boats, last for a few seconds (40 to be precise). The Rocket Drone could be launched, staying in the air for a good 10 minutes, prolonging the duration of the distressing signal, improving dramatically the chances of being seen and rescued.

Of course, in both scenarios the Rocket Drone has to be autonomous.
I'm looking for a Company keen to help me in developing fully this project.
 
Last edited:
#8
How about a pair of folding coaxial props? It might be possible to skip the cyclic control and control with movable fins, which are already there. This ought to be more streamlined for better launch performance. When folded, the props could probably withstand high airspeeds.
 
#9
How about a pair of folding coaxial props? It might be possible to skip the cyclic control and control with movable fins, which are already there. This ought to be more streamlined for better launch performance. When folded, the props could probably withstand high airspeeds.
Regrettably an attempt like this has been done by the Rotary Rocket, with no success. I mean, it flew 4 times, reaching the maximum altitude of 3,000 metres, using the single rotor blade. Test pilots said it was very difficult to fly (rated 10 in the Cooper-Harper scale), Eventually, with the configuration you have suggested, you should use a gimbal, attached to a contra-rotating motor, with 2 coaxial propellers.

https://www.youtube.com/watch?v=AI4LI4DgiOw

This solution is excellent, but just looking at the battery, 2 things come to my mind:
1. The battery itself looks pretty heavy and my goal is to launch the Rocket Drone using Low Power Rocket Motors (D or less), in order to broad as much as possible the use of it.
2. Using the configuration of the contra-rotating motor, the LiPo battery will be too close to the rocket engine. Not mentioning that having the battery in that position, moves the CG of the Rocket to the tail, making nearly impossible to have a predictable trajectory during the launch.
Pretending that the CG placed at the bottom of the Rocket, doesn't affect the flight of it, during the thrusting phase the rocket motor reaches temperature of 300 degrees Celsius... I believe it would be a bit dangerous to have the LiPo battery nearby. :)

Last, but not least, to control the movable fins according to the position of the rocket, an Inertial Measurement Unit, an Arduino and 2 servos (at least), should be added, increasing furthermore the weight of the rocket.
 
Last edited:

b-29er

Active member
#10
I love the idea, but if you're trying to go lighter, here's a thought. Use four servo retracts, hook the arms up to the retracts, and hook all four retract mechanisms up to a decent size servo. Use sub-250 racing quad motors and small props so the motors can tuck into the rocket fuselage (this will probably require reinforcing the fuselage with balsa). Finally, use a lightweight FC with built in ESCS and a low weight, high draw battery to power the thing. The point is, you have a relatively low weight system that doesn't retard aerodynamics for higher altitudes flight. Once you get past launch apogee, you extend your motor arms, and boom, VTOL landing. If you also put plates on the arms, when you extend the arms, you will change the center of drag relative to the center of mass and the rocket may flip to a tail-first position for landing.
 
#11
I love the idea, but if you're trying to go lighter, here's a thought. Use four servo retracts, hook the arms up to the retracts, and hook all four retract mechanisms up to a decent size servo. Use sub-250 racing quad motors and small props so the motors can tuck into the rocket fuselage (this will probably require reinforcing the fuselage with balsa). Finally, use a lightweight FC with built in ESCS and a low weight, high draw battery to power the thing. The point is, you have a relatively low weight system that doesn't retard aerodynamics for higher altitudes flight. Once you get past launch apogee, you extend your motor arms, and boom, VTOL landing. If you also put plates on the arms, when you extend the arms, you will change the center of drag relative to the center of mass and the rocket may flip to a tail-first position for landing.
I've checked the weight of the drone sub-250 and they are between 150-180 grams (without the battery), which is the same weight of the quadcopter I used to build the Rocket Drone. Adding the retract mechanisms (instead of my nylon self-locking-hinges-remotely-controlled), would bring the weight abundantly above the 400 grams threshold. This weight allows me to use D motor (aka Low Power Rocket Motor) and as I've previously said, I'd like to keep the Rocket Drone accessible to everyone.

I haven't used a servo to lock the arms in place, because it's unnecessary.
In fact, after the thrusting phase, the rocket experiences nearly 0G due to the brutal initial acceleration. As soon as the drag is lowered (apogee), if the rocket wouldn't coast, the arms would go up by themselves. Throttling up the motors, though, locks the hinges firmly, making the flying experience less "nerves wrecking" and, most important thing, safer.
I could have built a fairing that covers the shafts, leaving the propellers free to spin.
The 1st conundrum is that the Rocket Drone is long 50cm, therefore the fairing/cover for the shafts would have reached nearly the tail, affecting the work of the fins. The second conundrum is that fins have to stabilize the rocket during the launch, without interfering with the prop wash during the landing phase.
The Rocket Drone may look easy to build, but trust me, it's not! :)
 
Last edited:

b-29er

Active member
#12
I've checked the weight of the drone sub-250 and they are between 150-180 grams (without the battery), which is the same weight of the quadcopter I used to build the Rocket Drone. Adding the retract mechanisms (instead of my nylon self-locking-hinges-remotely-controlled), would bring the weight abundantly above the 400 grams threshold. This weight allows me to use D motor (aka Low Power Rocket Motor) and as I've previously said, I'd like to keep the Rocket Drone accessible to everyone.

I haven't used a servo to lock the arms in place, because it's unnecessary.
In fact, after the thrusting phase, the rocket experiences nearly 0G due to the brutal initial acceleration. As soon as the drag is lowered (apogee), if the rocket wouldn't coast, the arms would go up by themselves. Throttling up the motors, though, locks the hinges firmly, making the flying experience less "nerves wrecking" and, most important thing, safer.
I could have built a fairing that covers the shafts, leaving the propellers free to spin.
The 1st conundrum is that the Rocket Drone is long 50cm, therefore the fairing/cover for the shafts would have reached nearly the tail, affecting the work of the fins. The second conundrum is that fins have to stabilize the rocket during the launch, without interfering with the prop wash during the landing phase.
The Rocket Drone may look easy to build, but trust me, it's not! :)
There are actually some way small racing quads (sub 150mm) like the Emax Babyhawk that have very potent brushless motors and sit under 100g without a battery. Actually, if the data is to be believed, or even off by a decent margin, This set of brushless motors with a set of 2" 4-blades or more than likely some 3" 2-blades would be more than enough to correct 400g of freefalling model rocket. Pair with this 20mm stack and you're at about 35g without a frame, something i assume would have to be custom tailored. Pair with a 3s lipo that can support a burst of 40a, add 30-40g for the frame, and you're right about at that 140g you are talking about. The difference is a brushless motor setup with such tiny props would be much easier to conceal in the fuselage to improve aerodynamics (think inverted motor mounting so the motors and props retract into the aircraft), which is almost as important as weight in these rocket systems, as having a draggy airframe will reduce the coast phase of the rocket, reducing max altitude.

Which was why i brought up the folding mechanism, but it seems you have one that works a lot better and is much lighter than i suggested. nice! And with your props unfolding during the coast phase automatically, you may find your rocket automatically flips around anyways once you start testing pyro rockets, which would help out with recovery.

And yeah, i have yet to have someone walk up to me and say "pssh, its just rocket scence!" Keep it up, looks neat. I may have to try this if i find time after my next project
 
#13
There are actually some way small racing quads (sub 150mm) like the Emax Babyhawk that have very potent brushless motors and sit under 100g without a battery. Actually, if the data is to be believed, or even off by a decent margin, This set of brushless motors with a set of 2" 4-blades or more than likely some 3" 2-blades would be more than enough to correct 400g of freefalling model rocket. Pair with this 20mm stack and you're at about 35g without a frame, something i assume would have to be custom tailored. Pair with a 3s lipo that can support a burst of 40a, add 30-40g for the frame, and you're right about at that 140g you are talking about. The difference is a brushless motor setup with such tiny props would be much easier to conceal in the fuselage to improve aerodynamics (think inverted motor mounting so the motors and props retract into the aircraft), which is almost as important as weight in these rocket systems, as having a draggy airframe will reduce the coast phase of the rocket, reducing max altitude.

Which was why i brought up the folding mechanism, but it seems you have one that works a lot better and is much lighter than i suggested. nice! And with your props unfolding during the coast phase automatically, you may find your rocket automatically flips around anyways once you start testing pyro rockets, which would help out with recovery.

And yeah, i have yet to have someone walk up to me and say "pssh, its just rocket scence!" Keep it up, looks neat. I may have to try this if i find time after my next project
Having a proper budget the Rocket Drone should be autonomous and equipped with brushless motors.
The suggestion you have made about the 3 inches propellers though, should be tested.
The choise of the 8 inches propellers is not "accidental". Using this size creates a lot of drag when the shafts are deployed, shifting the CP (centre of pressure) behind the CG (centre of gravity). In this way (after launch), the Rocket Drone keeps the vertical position and it's ready for landing (without performing any flipping).
Large props also spin slowly, giving great static and low speed thrust, but low pitch speed. The small props spinning fast have a low static thrust, but a higher pitch speed meaning a higher flying thrust and higher top speed for the model.

Now that the Rocket Drone has been built, it looks pretty simple, but after all, we are still talking about rocket science here. :)
Anyway, I look forward to seeing your version.
 
Last edited: