Aerodynamics Discuss the physics of flight revolving around the aerodynamics and design of aircraft.

four rotor toy

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Old 11-28-2010, 04:27 PM
  #1
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Default four rotor toy

Most have probably seen the new four rotor toy (ARDrone)which can be flown using a hand held phone ($300)
It goes up,down turns etc., all based on the inputs recieved from a hand held phone's gyro /stabilizing info.
from person's movements to a computer which directs motor(s) speed All of the flight motion is accomplished by simply varying motor speeds to the four fixed pitch props

After seeing the horribly complex machines such as the OSPRY , I wonder if this basic simple approach is not going to be used as a man carrying transport.
What is wrong with this simple approach? The solid state computers do all the real brain work It can be accurately flown by even totally untrained personnel and the parts count is extremely low
Lifting ability is also very good
Many of our old concepts such as airfoil shapes and propeller shapes have already been quietly been packed away in the album of past experiences and we now fly stuff once thought completely impractical or impossible.
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Old 11-28-2010, 06:22 PM
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Default RE: four rotor toy

Very plausible with newer materials and electronics.

Regular helicopters are complicated but still practical, regarding transmission of power from IC engines, centering of mass, cargo access and "wing"-span.
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Old 11-28-2010, 11:02 PM
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Default RE: four rotor toy

A few reasons.

First off the model uses easily controlled and highly reliable separate motors. The full size helis have to rely on coupling shafts so that both rotors can be turned by a single engine or linked engines that can still turn all the rotors in the event of a power failure. As I recall the Osprey uses a linkage shaft between the two tip mounted engines just for this reason. Otherwise an engine out on the Osprey would be ...er... shall we just say "interesting"? So until we can make a setup like this model where all four rotors can either be powered by highly reliable power sources or a single source with a highly reliable and light power trasfer shaft network to all four rotors I think that such a vehicle is only suitable for unmanned models.

Then there's the issue of what happens if the power source dies. On a single or dual rotor helicopter the rotors are large enough that they can go into autorotation and still supply enough lift to "glide" down to an abrupt but highly survivable landing. But something with such small ducted rotors does not have the blade area or favourable aerodynamics of the small rotors to allow them to autorotate fast enough to supply the sort of cushion that would be needed. So in this case of the power goes away the vehicle would likely tumble and return to earth rather abruptly.

Finaly the whole point of the swing rotors of the Osprey was to be able to beat the speed limit imposed by the leading and trailing rotors. Something that this 4 rotor vehicle can't do. In fact forward speed of such a vehicle with the ducts and rotors fixed would be poor compared to speeds that could be achieved with either a regular heli or in an Osprey like vehicle because of this.

Now if the rotors and ducts were mounted at the tips of some wing surfaces and were able to swivel to allow transition to forward flight that could well be a whole other ballgame. But then we're back to complex drives that are heavy, fragile and expensive.
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Old 11-29-2010, 11:10 AM
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Default RE: four rotor toy

Well you make a case for the Osprey-
however
The craft does not rely on ducts - those are just there for safety reasons.
Electric motors of this type setup have a rotor and two bearings.
Those are the only moving parts -so- a central motor and drive shafts are really not required
The inherant safety and simplicity of individual electric motors along with the proven track record of these type motors , makes the configuration far better (my opinion) than the involved setup of the Ospry.
If you think I don't like the Osprey concept - you are correct.
My bet is that this multi type setup will end up replacing the involved setups -once the political forces driving the Ospry type machines , is exhausted.
Involved and expensive military equipment will be less attractive in the future (my opinion again)
The costs of maintaining this approach to insuring our nation's safety is becoming more and more contoversial.
The industrial /military complex is not a myth.
I am not a Dove - just looking at what could be a far more practical approach.
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Old 11-29-2010, 11:56 AM
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Default RE: four rotor toy

I think that the only thing holding such a concept back for use in full scale aircraft is battery technology. It is just in the past couple of years we have seen the advent of electric powered GA aircraft, as our battery technology gets better I think that we will see more and more small aircraft go electric.
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Old 11-29-2010, 02:10 PM
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Default RE: four rotor toy

Iron Eagle raises a good point about how electric motors are becoming more useable in full size avaiation.  With a simple and reliable solution such as motors on a 4 rotor craft such as this we could see efficiency and safety all coming together well enough for manned flight. 

It still leaves the issue of forward speed limits though.  Also the idea of incorporating some wing area into the shape.  It's pretty obvious that props or rotors are not as efficient for lifting and moving payloads at speed but they have the advanatage of VTOL.  So SOME wing area to aid in carrying the weight at cruise speed would allow more of the rotor thrust to be used for speed instead of lift.  Again that is the whole strong point of the Osprey and similar concepts.  They even recognized this issue back with the old Fairey Rotodyne when they gave it a small wing. 
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Old 11-30-2010, 01:35 PM
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Default RE: four rotor toy

Woudl be easy enough to make the entire airframe a rectangle with the four motors set up in a synchronised fore/aft tilt
lift to altitude then tilt n go
With the present computerized stability setups possible - it would make possible a hybrid flying wing/heli
Anything is better than the OSPRY setup
That thing is an overpriced death trap
Again -just my opinion
It amazes me how inspired the present day toy makers have adapted the latest in technology to come up with devices that outperform multi billion dollar research projects funded by the government
Kinda like Rutan's stuff .
I guess when the goal is to make money based on "cost plus " engineering research , it should not come as a surprise that manytimes the end results are overly complex and incredibly overpriced.
I have watched various Looney Tunes projects originated then,kept alive simply to try and maintain levels of funding -from year to year.
Watching the advances in Chinese electric power technology - it would not surprise me to them leapfrog our present "highest levels of technology"
Greed n Pride can be as dangerous as any foreign potential threat.
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Old 12-01-2010, 05:37 PM
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Default RE: four rotor toy

Dick,
Your right we are going to "left in the dust" as far as technology, for decades now most American businesses have focused on the next quarters profit rather than any long term view.
I think you are right the next versions of STOL/VTOL will be very interesting and it is time for somebody to apply the new "toy" technology of computer enhanced flight.
I know for years now Moller has tried without success to apply multi-engine lift technology with computer control to a VTOL craft.
I have followed the "phone drone" for some time now and think it may be a hint of the future in aviation.
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Old 12-01-2010, 09:44 PM
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Default RE: four rotor toy

What technology are they using that wasn't developed in the States?

BTW, the MikroKopter or HexaKopter is much more impressive in performance.
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Old 12-02-2010, 06:53 AM
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Default RE: four rotor toy

I would say that a good part of it stems from technology developed here, but I can't say for sure as toy is produced by a company in France. Where we are going to run into problems is that today very little of actual production and research is done in the US today, the majority of it is done off shore. As an example for years before I went to work in newspapers I worked in electronic manufacturing and research, very little of that is still done here today for the most part it is all done on the pacific rim. When it comes down to it today very little electronic production work is done in the states and in the long run that is going to hurt us. Take a look at the vast majority of products on the shelf in stores, very little says made in USA...
Perot was right!
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Old 12-02-2010, 08:10 AM
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Default RE: four rotor toy

BTW the Joint Strike Fighter just got upgraded to an estimated 92 million bucks a copy - In the words of Porky Pig

ttttthats all fffolks!
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Old 12-02-2010, 09:53 AM
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Default RE: four rotor toy


The Wrights crashed and killed the passenger, Lt. Selfridge from the US Army at a demonstration of their flyer at Fort Myer, VA.
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Old 12-02-2010, 09:59 AM
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Default RE: four rotor toy

Come on -hardly the same thing
The "cost of air superiority" argument has gotten a bit out of hand
almost like battling to see who goes to the planet Mars first .
The US outspent Russia to bring the Cold War to a close .
The whole International political picture now resembles Alice in Wonderland.
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Old 12-02-2010, 11:09 AM
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Default RE: four rotor toy

Quote:
ORIGINAL: Tall Paul


The Wrights crashed and killed the passenger, Lt. Selfridge from the US Army at a demonstration of their flyer at Fort Myer, VA.
Yes they did, but they personally referred to them as hard landings.
As a matter of fact Lt. Selfidge was the first aviation fatality.

And I have gone some serious gopher hunting as well!
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Old 01-04-2011, 04:15 PM
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Default RE: four rotor toy

Quote:
As a matter of fact Lt. Selfidge was the first aviation fatality.
He was the first to die in heavier than air powered flight. Gliders killed a few before with Otto Lilienthal the most famous to take an early dirt nap.
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Old 03-16-2011, 01:43 PM
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Default RE: four rotor toy

Yes you are right. And as you pointed out many others had lost their lives in the pursuit of human flight before that.
To me the age of modern aviation started with the first heavier than air powered flight and that was the what I was thinking when I replied.
Sorry it took so long to reply, I had misplaced the email and just now came across it...
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Old 03-16-2011, 03:55 PM
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Default RE: four rotor toy

I thought Selfridge was the first US MILITARY OFFICER to die in an airplane crash. Surely others attempting powered flight had died before that point.
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Old 03-16-2011, 04:15 PM
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Default RE: four rotor toy


Quote:
ORIGINAL: BMatthews

I thought Selfridge was the first US MILITARY OFFICER to die in an airplane crash. Surely others attempting powered flight had died before that point.
were any flying in a FOUR ROTOR TOY?
I think not
So -yet more proof how safe the four rotor design is
(steering the thread back on point)
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Old 03-16-2011, 04:45 PM
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Default RE: four rotor toy

All I know is i'm not letting some text happy 20 something fly my keister around with his phone.[X(]
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Old 03-16-2011, 05:23 PM
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Default RE: four rotor toy

Today I watched two RCfliers fly new tiny one ounce helicopers with new DX8 radios - the copters had full collective pitch and wer fully aerobatic - I looked long and hard at the 1 inch by 2: circuit board which contained among other things a three axis gyro and a 2.4 rx plus an esc and two servos
the helis were absolutely glass smooth , steady -and lightning fast in response
The TX have only a small board in them too. Point being - the miniaturization of electronics is changing ALL the old rules and flying with a peizo pad is not as strange as it sounds -
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