PDA

View Full Version : Paramotors & Paragliding


Cognisant
10th-January-2014, 06:14 PM
So I want to make a paramotor UAV and the only part I'm really hung up on is the parafoil itself, now I can go out and buy ripstop nylon fairly cheap but I don't know of any parafoil templates and I don't own a sewing machine so it would be a pain in the ass to make one.

Commercial parafoil kites aren't cheap, so far the best I've found is $139(Aus) for a 2.5m foil which is a bargain compared to some of the other prices I've seen, but is a parafoil kite the same as a parafoil chute?

The reason I'm looking into paramotor technology is that, at least in theory a drone could take off and land in a very small space, almost like a helicopter but with efficiency more like that of a glider

Blarraun
10th-January-2014, 06:44 PM
So I want to make a paramotor UAV and the only part I'm really hung up on is the parafoil itself, now I can go out and buy ripstop nylon fairly cheap but I don't know of any parafoil templates and I don't own a sewing machine so it would be a pain in the ass to make one.

Commercial parafoil kites aren't cheap, so far the best I've found is $139(Aus) for a 2.5m foil which is a bargain compared to some of the other prices I've seen, but is a parafoil kite the same as a parafoil chute?

The reason I'm looking into paramotor technology is that, at least in theory a drone could take off and land in a very small space, almost like a helicopter but with efficiency more like that of a glider
Your UAV would be dependant on the wind currents and general weather.
As a person with 2 family members using the parafoil/paragliding:
Travel requires good weather and rising currents that help you increase velocity and potential energy. Otherwise you need a high altitude to fly from top to the base of the elevation.
This is very much alike sailing a small boat.
Efficiency relies on the good readings of wind currents and wind slopes, you have a measuring tool that indicates the rate of climbing in m/s.
Additional info:
Speeds from 20-60 km/h
Chutes and wings differ they range from recreational to sport/extreme, where efficiency and reactiveness increases and forward/upwards potential is different
Efficient gliding can allow you to travel as far as 150-200 kilometers.
Having a paramotor makes everything less glidy and more fuel reliant. I don't know much about windreading in motorgliding, it is rather closer to propelled flight.

It is very unlikely for you to be able to manufacture an efficient wing, with a good aerodynamic profile.
It is very unlikely to create an uav out of a balancing parachute frame.

I would recommend making first UAV's from helium baloons to test communications and devices that you want to install.

Cognisant
10th-January-2014, 07:42 PM
What's your thoughts on these?

http://www.hobbyking.com/hobbyking/store/%5F%5F14284%5F%5FHobbyKing%5FParaglider%5FParafoil %5F2%5F15m.html

http://www.kitepower.com.au/ozone-imp.html

I like the Hobbyking price :D

I already have motors, batteries, sensors, radio receivers/transmitters, servos, frame materials, fishing wire and who knows what else, and I don't mind losing/breaking stuff if I learn something, y'know the Adam Savage school of science.

crippli
10th-January-2014, 09:45 PM
The cheapest way would probably be to get an old paraglider(for free). Snipp off the ends, and sew them together. For more accuracy you can play with the design (http://sourceforge.net/projects/foilmaker/). Maybe read through this (http://foilivier.free.fr/uk/index.htm)first. Make an ad here (http://www.paraglidingforum.com/index.php), and I bet someone will give you an old glider for free.

If you want it to go fast, and get more advanced. You can convert the design to reflex (http://en.wikipedia.org/wiki/Paramotor_Reflex_Wing_Profile).

Or buy one. That will be more expensive though, as you found out.

Cognisant
10th-January-2014, 09:52 PM
Extremely helpful, thank you.

crippli
11th-January-2014, 12:42 AM
Cool. I think I would have gone with a rigid wing. Less deviations from aerodynamics. And a different world in performance. You can get rigid wings down on low stall speed. And in that regard, your quadrocopters are unbeatable. But there is a coolness factor, so I like it. Wish you luck.

As I have thought about this myself, but not done much research. How will the control system work? Will you be able to autopilot it? I'm dreaming about a solar powered drone, that goes up when one is done with it, and stays there(undetectable by radar, and avoidance sensors to other objects) and one brings it down when one need it.

Blarraun
11th-January-2014, 01:10 AM
What's your thoughts on these?

http://www.hobbyking.com/hobbyking/store/%5F%5F14284%5F%5FHobbyKing%5FParaglider%5FParafoil %5F2%5F15m.html

http://www.kitepower.com.au/ozone-imp.html

I like the Hobbyking price :D

I already have motors, batteries, sensors, radio receivers/transmitters, servos, frame materials, fishing wire and who knows what else, and I don't mind losing/breaking stuff if I learn something, y'know the Adam Savage school of science.
The first design is more appealing, if only for the fact of it being shaped properly.

The carrying capacity appears to be 1400-1600 grams including the wing mass.
This would be enough for some small cameras/sensors besides motors.

I would say that it can operate on a short distance, around your vision/signal range, maybe ~1-2 km. Depends on what you need.

If you consider gliding power, I would dismiss that. The mass of your wings and carrying capacity are not enough for these designs to allow for a proper gliding, you could try it out, however I predict that in reality once you turn your engine off the parachute would likely lose shape and crumble to the slight gusts.

Paragliders weight significantly more and properly force the attack angle so that the wind passes through, I wonder what would happen with this miniature. It could be fine.

Usually paraglides can carry 60-70 kg of mass.

I support the idea of a fixed or reinforced wing. This helps when your mass is low and improves steering. Unless you try to land within a very small area you don't require too much runway for 2kg UAV. Usually a few steps.

Words
11th-January-2014, 01:48 AM
I thought you were concerned with self preservation? This activity does not exactly increase your chances of immortality.

Cognisant
11th-January-2014, 09:57 AM
It's one of my one going projects to create an inner city drone based delivery service, at first I was going with quadcopters but VTOL takes a lot of power, I tried making it turn on its side so it could use the arms as wings but there were pitch & yaw control issues, also standard GPS alone has a 10m margin for error and that's just too unpredictable for something operating under 100m without direct supervision.

So the current idea is basically a ripoff of the JPAD system, the drone is going to release the goods at about 200m or higher, the package will parachute down and servos and a receiver in the package will enable people to steer it down to them with their smartphone. I could just use a plane for this but the large colourful canopy and slow speed of a paramotor make it attractive from a safety standpoint, also if I lose a drone it'll be cheaper to replace.

If you consider gliding power, I would dismiss that. The mass of your wings and carrying capacity are not enough for these designs to allow for a proper gliding, you could try it out, however I predict that in reality once you turn your engine off the parachute would likely lose shape and crumble to the slight gusts.
I definitely want it to glide down if it loses power, safety is very important because I'll have to get approval from the CASA before I'll be able to operate a drone based business and safety is all they really care about.

Cognisant
11th-January-2014, 12:32 PM
I ordered a few of the Hobbyking parafoils yesterday so I'll get them Monday or Tuesday, now is is the motor they recommend (http://www.hobbyking.com/hobbyking/store/__18119__turnigy_aerodrive_sk3_3536_1400kv_brushle ss_outrunner_motor.html) and I've got the Droidworx Axi 2814/22 which I believe will be more efficient as it's designed for a larger propeller, which I have.

As Blarraun pointed out this won't be big enough to deliver packages but it'll suffice for testing and the parafoils I've ordered should be suitable for delivering the packages when I get to that, assuming they actually work like parachutes and don't just collapse at low speed, in any case we'll see and I can always cut out the stitching of one and scan the panels so I have somewhere to begin designing my own.

Blarraun
11th-January-2014, 12:50 PM
Are you also into UAV algorythmical flight control?
Essentially Fly-by-wire/wireless (http://en.wikipedia.org/wiki/Fly-by-wire). You could have headquaters with a computer ordered flight controls and a few people to manage the larger units that transport entire containers of packages and deploy smaller delivery drones, it would also be a reload and recharge base. Am I taking it too far :p?

Instead of dropping the drone in the vicinity of a destination and having a customer guide it, that can be fun,you could have it locate her/his cell phone signal or sense the music/house and move to that location.

Cognisant
11th-January-2014, 02:01 PM
Am I taking it too far?
Never.

The idea is that people order their products by smartphone, possibly via an app but a website would be so much easier and they'd have to register by web anyway. Once registered they order what they want, they send me their GPS location (which isn't just GPS because cellular network triangulation is involved, but it's all functionally the same) and my computer tells a loading mechanism to load the drone with the package.

Once loaded the drone is launched (catapulted off the roof of a building), now if the drone is a plane this will be outside the inner city where I can find cheap office space and a nice big roof, or with the paramotor it can be thrown off an inner city tower, as was the intent with the multicopters. The reason for the difference is landing, even a slow plane needs some distance to safely decelerate whereas a paramotor could land almost like a helicopter, making it suitable for small rooftops, although the wind would likely be an issue. Probably the best middle ground would be a tilt body craft that flies like a plane but lands vertically, it wouldn't even need to have enough power to stay in the air vertically, just enough to decelerate its descent.

Once in the air the UAV gains altitude to about 200-300m and then heads straight for the GPS waypoint and once the package is dropped it may circle for a minute or so (because the customer's phone isn't directly controlling the package) before flying home to ideally (now this is the hard bit) land on its own and be automatically recovered and recharged, ready for reuse.

The customer doesn't control the package directly because then they might steal my receivers or someone else could read the app data and steal control of the package, instead their phone either connects to my computer which then relays the instructions to the drone which then tells the package what to do. Or because I'm thinking I'll use an Android phone as the brains of my drone the customer could just call the drone (which will only accept a call from the registered number) and then they can control the package by pressing the 1 and 2 keys (tone based control).

the larger units that transport entire containers of packages and deploy smaller delivery drones
Like some kind of flying aircraft carrier? Awesome.
I could do that with a blimp of some sort although there's really no point to it and it wouldn't be able to carry much product, likewise a floating platform could save me from renting office space but there's all kinds of issues with that as well.

But hey if this really takes off (punny) maybe one day I'll be able to afford a proper UAV carrier ship and sail around the world selling sushi fresh from the sea :D

Cognisant
11th-January-2014, 02:16 PM
The packages are paragliders with a single servo that controls steering by alternately reeling in one string and unreeling the other, a 2.4ghz spread spectrum receiver (very reliable) it's all powered by a capacitor with a simple voltage control circuit. I'll be 3D printing a plastic container with tubular/modular sections, so whether it's sushi, waffles, or whatever people can have whatever mix/quantity they want. The part containing the components will designed to replace the servo casings and the receiver will be soldered in to make it as hard as possible to steal them, which is probably the biggest problem with all this, the package components will cost more than the contents.

Which I have a plan for, the package (drop control unit) will already have a postage stamp on it so once they're done with it the customer just pops it in the mailbox and it gets returned to me, by making it difficult to get into and the parts difficult to reuse there's little incentive to take it apart, the customer pays a small deposit on each delivery which is returned upon the safe return of the drop control unit and if someone doesn't return them a few times I either raise the deposit or cancel their registration and blacklist them.

Cognisant
11th-January-2014, 09:28 PM
Anyone got thoughts on the package power supply?

Currently my options are two 3.7v 500mAh Lipoly Batteries in series with a 5v regulator, or two 55farad 2.5v supercapacitors in series which works out to about 27farad at 5v.

The batteries need to be charged properly and I have a charger but I'd prefer to go with the capacitors and a simple 5v USB charger, partly due to the the simply, partly because it's cheap, but mainly because (unlike LiPoly batteries) they'll keep working (practically speaking) forever.
But will 27farad be enough?

Blarraun
11th-January-2014, 09:56 PM
2*0,5Ah=277.777777777777μA
P=5V*277.(7)μA=0.001388(8) W/s

Capacitor for 5v with 27 farad:
27=C/5, 135=C, for time of 1800s=0.5h
A=135/1800, A=0.075
P=0.075A*5V=0.375 W/s
Capacitor : Battery|||Capacitor for 30 min scenario seems to be edit:731 270 times more effective, power-wise

This obviously abstracts power supply consistency, assumes perfect scenario, 0 resistance etc etc.

Corrected this stuff ^, initially I calculated for 1 battery

Using an ultracapacitor/supercapacitor seems to be a very good idea, from what I have seen/learnt they tend to be good for short high power stuff.

I don't know if they are so infinite compared to batteries but it would be worth testing.

Cognisant
11th-January-2014, 10:58 PM
I thought F=C/V and C=AxS/V, except capacitors tend to be listed with "Farad at Voltage" so the division is already done for us, so 27F is 1A for 27seconds.

27/60= Amp minutes = 0.45
27/60/60 = Amp hours = 0.0075 or 7.5mah

7.5mah seems pathetically small but that's 7.5miliamps constant for one hour when at most I reckon the package will need 5min so 7.5x12=90 now a constant 90mah for five minutes should be just about enough.

Blarraun
11th-January-2014, 11:17 PM
I should add how I am not yet confident in my physics, need to get on my introducing physics in 2nd year course.
I wanted to try anyway. I don't feel enough confident to ascertain and post anything regarding this so I will back away and maybe when I have time to read in I will be able to come up with stuff to capacitor/battery.

Cognisant
12th-January-2014, 12:23 AM
Formal education? Bah! Google sensei teaches me everything!

Cue Architect showing up and schooling me with his master physicist fu.

Blarraun
12th-January-2014, 12:25 AM
I don't expect formal education to be any good as it was never my basic source of information, rather an outline and confirmation of competence in a tiny subject stripped of interesting information and heavily abstract on self-validating paperwork. I think that by that time period I will have enough time and/or incentives to work it out.

Cognisant
12th-January-2014, 03:14 AM
Went to Jaycar (our version of RadioShack) and got some small servos, motors, diodes, LEDs, resistors and the 55F supercapacitors.

Geheheheheheheheheheheee :D

No-no-no I will not go discharging them on things just to see what happens because I'm a sensible, responsible adult.

Buahahahahahahahahahahaaaa

Cognisant
13th-January-2014, 11:55 PM
So I've decided the delivery UAV will be a plane (cheaper to rent working space outside of town) so I'm trying to figure out how to design a wing body, but the calculations make no sense, I need to know the Lift Coefficient to calculate the Lift Force and the Lift Force to calculate the Lift Coefficient.

Whaaaaat!?! That's not fair!

crippli
14th-January-2014, 01:32 AM
...your tagline is wicked...

Anyway. Do you have access to a university? perhaps they have a windtunnel where you simply measure these coefficients. You may get grey hair if you try to calculate the overall amount of lift in your design analytically in 3D. Not sure how valid it will be in 2D. Seems stuff ends up in labor intensive differential equations. Especially if efficiency of design is your goal.

So, I would do a shortcut. Find some computational fluid dynamic program(CFD). And they will do the math for you. Send a PM to ProxyAmenRa, he would know more about this, if I remember correctly. Think he did bridges. But these can be used for any fluid that flows. Or just do the windtunnel. I would do the CFD, as it's more fun then physical testing. The translation to mechanics FEA(finite element analyses) is not so different. FEA will be useful for the 3D printing I seem to remember you have plans for.

It's interesting to see how your various ideas do connect together. Personal I'm a fan of computer analyses. But how the accuracy translates to real conditions, I don't know. Perhaps do an extra high factor of safety, at least on the critical components, if the plane becomes big and stuff.

Otherwise, I prefer to look simply on things as lift using Bernoulli principle(i suck at physics..just pretend I understand the aviational aspect, since it's interesting) and Reynolds number. Mix in Newtons third and second law of motion, various polar curves of aviation, and simple aerodynamically principles, and I feel I get an idea of why things fly. I do not feel confident enough yet to design a real plane(I have wanted to).

Cognisant
14th-January-2014, 02:01 AM
I've found this site (http://www.mh-aerotools.de/airfoils/flywing1.htm) which seems helpful.

Ideally I want to design a swept flying wing with internal ducted fans, something like a modernised Horten Ho 229 with maybe a proportionately wider wingspan. I could just build that from reference pictures and that seems to be what most RC modellers do, with an adjustable internal weight distribution and large control surfaces to make so even if it dosen't fly well it still flies. It may not be perfectly efficient, then again if it's dropping a third or more of its total weight the power to weight ratio will change significantly so as long as its peak efficiency is somewhere in that range I'll benefit either way.

Eh I dunno, expanded PPE isn't that expensive.

I'll coat the PPE foam with PVA and then a layer of plastic over that (seen it done for a Ironman cosplay, impressive result) which I'll sand and spray paint, that alone should be ridged enough but if it isn't I can have a balsa frame cut and/or run a carbon fibre rod through at an angle and use fishing line for tension support.

crippli
14th-January-2014, 04:51 AM
Horten Ho. Delta wings are ingenious. I have a delta foam wing. Super simple, and fly super well. They go both fast and slow. One can catch it with the hand if there is a breeze.

I kinda liked the parawing idea when what was the business idea. The huge surface is valuable for advertisement. There could be value in this that offsets it's less efficient flight characteristics.

ripoff of the JPAD system
As far as I can see goal is in reach when you have this. But isn't this some form of high tech super secret military system, a ripoff?

Cognisant
14th-January-2014, 05:25 AM
High tech super secret military stuff, ha haaa :D

Rule of thumb used to be that the military was at least a decade ahead of the open market but governments were the only ones doing proper R&D, nowadays private enterprise is leapfrogging them in almost every way. Simple fact is nobody can compete on equal terms with everybody, that's why you see modern militaries using modified off-the-shelf smartphones and Xbox controllers to control their scout UAVs, which themselves are often comprised of "hobby" motors and batteries.

I can buy GPS modules but they only work at certain velocities and under a certain altitude, but then unless I'm building an ICBM those limitations won't be a problem for me.

Cognisant
18th-January-2014, 09:51 PM
Flying wing plane is not happening, it can be done but there's almost certainly going to be a few prototype-destroying crashes before I get the trim characteristics fully worked out, which will be a little expensive and very time consuming. So instead I'm going with a more traditional design, the wings will be PPE foam cores coated with PVA then plastic, the forward fuselage will be 3D printed as will the tail and they'll be connected by a length of PVC pipe which by cutting to different lengths will enable me to easily adjust the plane's centre of gravity.

The real trick is going to be finding the CoG of the package and aligning it with the plane's CoG so dropping the package doesn't destabilise it.