SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Aug 09, 2012, 03:07 PM
SF Valley RC Flyers
Killionaire's Avatar
Joined Feb 2010
284 Posts
Discussion
Full size quadcopters?

Has anyone yet made a full scale quadcopter that can carry humans? Do you think this would have any military applications such as gunships and drones? I saw quadcopters used as spycams in the latest ghost recon game. Do those really exist?
Killionaire is offline Find More Posts by Killionaire
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 10, 2012, 01:26 AM
Crash and learn
United States, PA
Joined Dec 2011
1,605 Posts
Lunar_Landing_Research_Vehicle

Training for moonlanding I think used quads with jet engines. Didn't always work so well. Been a while since I've seen the video.

Guess not. Must have been the control thrusters.

http://en.wikipedia.org/wiki/File:Lu...000-000215.jpg

.
VZ-9 Avrocar

http://en.wikipedia.org/wiki/Avrocar

.
Ribble is offline Find More Posts by Ribble
Last edited by Ribble; Aug 10, 2012 at 02:32 AM.
Reply With Quote
Old Aug 10, 2012, 02:40 AM
Registered User
Joined Mar 2012
203 Posts
I remember seeing a 'quad for one man, he was controlling it with an R/C I think. The blades were right at the level of his head. Just simple hovering, very limited.

Alan
KM6VV is offline Find More Posts by KM6VV
Reply With Quote
Old Aug 10, 2012, 05:20 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
I don't know if a reasonably sized quad is possible to be made practical yet.

First of all, they require independent motors for each prop, which is a bit of a challenge to achieve, especially if duration is one of the goals. Why? because that goal would leave you with the only option for propulsion: fossil fuels.

Second, a quad relies on motors that act *quick* when change in torque is required. Those motors also need a *wide* range of speeds that they can oprate at, which, today is only possible with electric morors.

Note, that's only the first contradiction, and it already shows the drawback of a quad that makes it *really* unattractive in full scale applications.

Second point: If the quad in question is to use fossil fuels, then consider the complexity (and reliability/maintenance concerns) of four IC engines or the transmission connecting a single engine to four propellers.

Basically, the statement to the success of a manned quad is called "flying car" and has been in development for a few decades.

Gedexas is offline Find More Posts by Gedexas
Last edited by Gedexas; Aug 10, 2012 at 11:15 PM.
Reply With Quote
Old Aug 10, 2012, 07:13 PM
Registered User
Joined Mar 2012
203 Posts
It's been done, it's electric, and in my opinion, not too safe!

http://tosavetheday.blogspot.com/201...man-sized.html

Alan
KM6VV is offline Find More Posts by KM6VV
Reply With Quote
Old Aug 10, 2012, 11:14 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Forget it not being safe.

If traditional helicopters had a duration of ten minutes and flight range of a few hundred feet (and if they were powered by batteries, that would certainly be the case), they would be considered useless for all practical purposes.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Aug 11, 2012, 04:58 AM
SF Valley RC Flyers
Killionaire's Avatar
Joined Feb 2010
284 Posts
How about a gas engine used as a generator to power electric motors?
Killionaire is offline Find More Posts by Killionaire
Reply With Quote
Old Aug 11, 2012, 08:29 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Quote:
Originally Posted by Killionaire View Post
How about a gas engine used as a generator to power electric motors?
That's what the locomotives and ocean cruisers do, for precisely the same reason. It is easier to accelerate/decelerate and even reverse electric motors than it is to stop and reverse steam/diesel or even petrol engines.

The problem is you need a generator too and it's fine for a train or a boat, but a flying machine needs to weigh less, hence helicopters and airplanes not using electric transmissions.

If you were to use electric transmission in a human carrying quad, you'd end up with a combustion engine/turbine, a generator (generator four times the capacity of each electric motor, hence the weight), an AC to DC transformer, four ESCs, and four electric motors. If anyone knows how to modulate AC to four out of sync motors, without the need for DC converter, please let the world know.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Aug 11, 2012, 10:56 PM
Crash and learn
United States, PA
Joined Dec 2011
1,605 Posts
Quote:
Originally Posted by Gedexas View Post
If anyone knows how to modulate AC to four out of sync motors, without the need for DC converter, please let the world know.
Brushless motor is three phase AC and modulated by Electronic Speed Controller. Will even reverse. The frequency of the output doesn't change, so should be able to control a three phase AC motor with something similar to an ESC. Isn't like a three phase AC motor is something new needed to be invented.

Thyristors have been around for a while and someone has even invented a light dimmer using one.
Ribble is offline Find More Posts by Ribble
Last edited by Ribble; Aug 11, 2012 at 11:04 PM.
Reply With Quote
Old Aug 12, 2012, 12:48 AM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Quote:
Originally Posted by Ribble View Post
Brushless motor is three phase AC and modulated by Electronic Speed Controller. Will even reverse. The frequency of the output doesn't change, so should be able to control a three phase AC motor with something similar to an ESC. Isn't like a three phase AC motor is something new needed to be invented.

Thyristors have been around for a while and someone has even invented a light dimmer using one.
So, that's pretty much what I said.

Adjusting the speed of a three phase motor without converting AC to DC and back to AC is not possible, so the ESC would need to be used (a total of four meaty ones). I know this is a complex idea to comprehend, but it's not that complex.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Aug 12, 2012, 02:39 AM
mutski
United States, AK
Joined Jan 2011
1,192 Posts
Break a propeller and the pilot gets cut in half. Couldn't talk me into flying it!
mutski is offline Find More Posts by mutski
Reply With Quote
Old Aug 12, 2012, 01:51 PM
Crash and learn
United States, PA
Joined Dec 2011
1,605 Posts
Quote:
Originally Posted by Gedexas View Post
So, that's pretty much what I said.

Adjusting the speed of a three phase motor without converting AC to DC and back to AC is not possible
On the other hand, if it is impossible to control the speed, then all four motors would be turning at exactly the same speed and the quad would be very stable.
Ribble is offline Find More Posts by Ribble
Reply With Quote
Old Aug 13, 2012, 12:10 AM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
Quote:
Originally Posted by Ribble View Post
On the other hand, if it is impossible to control the speed, then all four motors would be turning at exactly the same speed and the quad would be very stable.
Actually, it would not be stable, not to mention the lack of ability to control it. Quads and other multirotors are not naturally stable, they require complex electronics with gyros to control the speed of each motor to keep them from shooting out of control.

Even at the size of a full scale aircraft, test flights have concluded that stability is an issue and extensive pilot training would be required to get a human to fly one of these things without assistance of artificial stability system.

Here's a particular multi-rotor I'm talking about:



This is a production vehicle available for sale as far as I understand, not surprisingly, these are not very reliable or practical vehicles.
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Old Aug 13, 2012, 03:25 PM
Registered User
Joined Mar 2012
203 Posts
Moller (?) available for sale? Do you have a URL?

Moller Has been promising the AeroCar for over four decades.

http://www.theregister.co.uk/2009/11..._on_the_ropes/

Alan
KM6VV is offline Find More Posts by KM6VV
Reply With Quote
Old Aug 13, 2012, 08:29 PM
CP heli ≠ 3D heli
Gedexas's Avatar
United States, NJ, Point Pleasant Beach
Joined Mar 2009
1,676 Posts
I was wrong, one of moller's vtol models was for sale twice and did not sell either time, since the bid reserve was not reached, but nothing is actually developed or approved for use or sale to the general public.

http://gadgets.boingboing.net/2008/1...ing-car-f.html
Gedexas is offline Find More Posts by Gedexas
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion how much money should i save up for a full quadcopter fpv setup? arctyler Multirotor Talk 20 Jan 21, 2014 12:27 PM
Build Log My ~$300 full quadcopter kit 1984 Multirotor Talk 26 Jul 11, 2012 08:32 PM
Discussion Das Plas-Stick (DPS) - E version full size rezzey SPAD - Simple Plastic Airplane Designs 13 Jun 29, 2012 05:35 PM
Sold FULL FPV QUADCOPTER with Headtracking+ Pro Kit wiseguy313 Aircraft - Electric - Multirotor (FS/W) 17 Jun 17, 2012 04:08 PM
Discussion Full size electric aircraft at EAA Fly-IN..time to start on a full size F-22;) Ed Waldrep Electric Ducted Fan Jet Talk 9 Aug 05, 2008 07:53 PM