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  • One more thing I thought of and what I think is happening here . The guy that is posting this stuffs name is Victor he is in love with cats.and is no dummy.
    He is a Researcher and software developer for a corporation Vista asta. Vista asta is a internet provider for Corporate Russia and it's internet cafees. internet cafes are popular because a lot of peope don't have access to the internet at home. comparable to Rogers, Bell, Telus,Exculink here . They also sell software packages in Russian, ver2 supervisor, helper,shell,money maker,tet vis 3' auto run manager They also have an on line Russian news paper some of the headlines." South western China Explosion internet cafe 6 dead ,""Computer games make people smarter ,more determined .""Odessa police accidently destroyed newspaper web site."
    "Microsoft hunt for Pirates in Moscow . Business man convicted of using cracked soft ware . and Vis Aata's new line of business building Quads and Hexicopters platforms for video cameras and such (like the one in the Arnold Palmer post). There was a bit of" cat and mouse . " International Intrigue".  I was looking at blog posts that were posted 2 years ago and he was coming along behind me and editing them "just now". When you ask vis asta
    to reveal how he does something ?  It is like asking Rogers or Bell or Boeing or Nasa to reveal their secrets. and I think they are gleaning information from you guys They post something that seems outrageous and you start commenting on what type of battery motors controllers etc would be needed and are  commercially available. 

  • Hi guys I have been browsing the Russian web site and I Gleaned some more information I also grabbed some numbers for you Rocket scientists out there to work . I got 8 grams per watt in hoover thrust . motors low kv type 4008c 600 0rb0 volt .copter weighhs 1300grams his buddy asks Why you need the air boost 5 dm2? Back in 2009 one of vis asta's buddies flew 90 minutes with this set up " Motors trmotor 3506 require 1.4a foer 3000g traction turns that require quadrics 5.6a weight 560g complete turns(regulation 4h 10g 20g of electronics motr.1 4h 70g frame 170g screws 4h 10g)next select the acc came to 1200g suitable 8400 mac evide 840 t05600 and get 1.5 hours or 90 minutes the weight can be further reduced .Then on the 10/11 2010 'What is the weigth of the electronics? Board 10g reciever3.8g zips and telementry not required distribution off power directly fine wire no regulation 10a weight 10g Then on 23/11 2011 props need 19''square 250 by 12s batareyka low c they are lighter motors hand made . and another guy got 90 min hoovering at 19g/vt.Don't ask me what any of the numbers Mean? I stop counting when I run out of fingers and toes . The 125 minute video was made 2 years ago. I also found out vis asta doesn't use GPS because he uses the Russian military Satellite system GLONASS and he was the first one in the world to use it on sept 14 2011 vis asta made a video comparing the 2 systems. GLONASS is a satellite navigation system operated by the Russian aerospace defense force an alternative to GPS in the early 2000s Valdimir Putins made the system top priority consuming a third of the Russian aerospace budget By 2010 GLONASS achieved 100% coverage of Russia and with the 24 satellites world coverage The satellites have gone under several up grades the latest GLONASS-K on vis astsa tests there were 15 satellites participating in the algorithm. I am all done being a detective . You guys have a Great Day I think Vis Asta is the real Deal .

  • @ Brad Hughey  I checked your web page That is quite a Flying machine you have there It looks like you got your plans from" Leonardo.  It is  is a perfect mathematical equation of  flight since you have the lift figured out . how about the Decent ? since it is a manned aircraft  are there redundant systems in place in case there is an emergency ? Will it glide ? looks like the ratio is 1/1

    Example: dual power systems each driving half the rotors  if one system fails the other is capable of flying the 

    air craft ? on a complete power failure  will it auto rotate? or is it a auto gyro and flies in auto rotation?

    Just a shot at your ground effect problem .could it be you have  so many small rotors working so close together each with their lift cone  the back wash of the ground is going back up and going through he top of other rotors randomly making them lose lift and the machine wobble  ?  

  • @R_Lefebvre: A) Did you happen to notice there is no "# of blades" variable in the induced power calculation?  Also, don't forget the INVERSE relationship between Re and Cd at these scales.  Slower is not necessarily better - in fact, at Re << 500K, it's WORSE.  To say for certain requires a bit of blade element analysis work.

    B) Yet to be determined - see "A"

    C) You may be partially correct, but not for the rationale you're using.  In order to maintain adequate control response in a fixed-pitch multicopter, blade radius (and therefore, rotational inertia) must be kept low.  That means that for low disk loading, the only solution is to add more rotor disks.  When you start heavy lifting, 4 props won't cut it.  To wit: the German pliates ball hopper had 16 thrust units, and my prototype has 36.  Again, disk loading, not number of disks, is the ultimate arbiter of efficiency.

    D) Yes.  I have one that can lift 230 pounds in my garage. 

  • Brad, yes, that is symmetric blades, and he's also running a really high 3D-typical blade speed of... what did he say, 2100rpm?  That could be dropped to almost 1200 with asymmetric blades.  Well, maybe not with a 40lb load.

    Just in case you're interested, I was playing around with some numbers, trying to guestimate flight time if those bricks were batteries instead:

    Heli Payload

    A while ago, Craig asked me about helicopters, and their performance relative to multi-rotors. Typically, you hear it stated that "helicopters are much more efficient than multirotors", but then when you actually look at the numbers, nobody is flying helis for more than 12-15 minutes, which is certainly achievable with a MR.  So are helis really more efficient?

    I believe yes, but the reason we don't see it in real life is because:

    1) RC Helis are designed and built for extreme 3D manoevers, not flight efficiency.

    2) To this end, they typically have extreme headspeeds, much higher than needed to actually fly.  

    3) They also use the minimum battery size possible to give a 6-8 minute acrobatic flight.

    My hypothesis is that:

    A) TH's have a theoretical advantage in that they have massive blade area compared to MR's.  But then they throw away that advantage by turning the blades far, far faster than needed for efficient flight.  Fixed Pitch MR's turn their blades at *exactly* the correct speed to generate enough lift to fly.  So they don't waste any power on propeller drag.  TH's however, typically spin far faster than needed, wasting an incredible amount of power on simple blade drag while they are hovering.  They do this so that they have tons of aerodynamic potential to achieve incredible roll rates and collective-pitch explosions.  To the point where they are in fact using blade inertia to supply power at a rate the motor can't even deliver for some manoevers.

    You can see this in the spreadsheet.  The specific power while hovering for that heli is 283 W/kg unladen.  But it has a minima of 140 W/kg with a 24lb payload.

    So to continue the theory:

    B) A typical hobby heli can achieve a much better duration by slowing down the blade speed to something more reasonable for typical UAV flight profiles.  They would further benefit from a more efficient blade profile.  

    C) When designed properly, a TH UAV system should be able to fly much longer than a MR with comparable capability.  Particularly when you start loading it up with payload.  That's the key point here.  An unloaded, 3D hobby heli is not as efficient as a typical MR.  But when asked to lift a heavy payload, such as a full-frame DSLR and gimbal, a heli is going to blow away the MR in duration. You can keep adding batteries to the TH to gain duration, with an almost linear return on duration.  But with a MR, you quickly fall off an efficiency cliff as you add more batteries to gain duration.

    D) A 700 heli can lift 30lbs of payload, yet comfortably fit in a golf-bag sized package for transport.  Have you seen what a MR looks like that can lift 30lbs?

  • P.S. This site REALLY needs a FAQ section.

  • @R_Lefebvre: Thank you.  I have a new "day job" with a corporate software startup, hence my lack of participation lately.  So, here's a run-through of the numbers on the stock TREX 700E example.  Apologies for the conversion to imperial units, but I'm used to 'em.

    Blade diameter is quoted at 1562mm, so that's 20.6 square feet.

    Total weight is 40.4 pounds.  (works out to about 2 lbs/sqft which is a typical D/L for single rotor helos)

    Square root of (40.4 pounds/2 * 0.00238 * 20.6sqft.) = 20.3 feet/second ^-1 and times our thrust is 820.1 pound feet/sec ^-1.  Dividing by 550 yields an ideal power of 1.49 horsepower or * 746 = 1.112 KW ideal induced power.

    If we assume a 70% efficient motor, then the rest is eaten up in rotor disk figure-of-merit for an FM of .665.  Not bad for what I'm assuming is a symmetrical blade section.

  • Dear friends, this moring I woke up thinking about the propelers design . I live in a rather hot clima , and i sleep with a  fan over me. I already noticed severall times that diferent brands of fans have very diferent wind power ..some do a lot of wind ..and some do almost none . My question is : How developed is our   propelers design ? what can be done to improve that ? what is the diference in having 2 blades or 3 ? what about a propeler with 4 blades ? 5 ? 

  • BTW Brad, you might find this interesting.  18.3Kg, 2390W.

  • criro, yeah, I've spent a lot of time playing with eCalc as well.  It's hard to get over 30 minutes, let alone an hour.  Even if you make a flying battery with zero frame weight.

    Brad: Problem is, we don't have any of those numbers.  Now, maybe you could crank something out using the best conceivable numbers you've ever seen?  Highest FM props, most efficient motors (95%?).  Highest W/g battery, zero frame weight.

    BTW, good to see you around, haven't seen you here in quite some time!

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