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Old May 13, 2013, 08:33 AM
CrashMaster
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United Kingdom, Brentwood
Joined Dec 2012
118 Posts
Quote:
Originally Posted by chanyote66 View Post
370 is the width... the weight is 940g
It is the weight.... I have just put mine on the scales
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Old May 13, 2013, 08:36 AM
CrashMaster
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United Kingdom, Brentwood
Joined Dec 2012
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Oooops mine is only 36Wh it must be smaller than the one they show on the link above.
Mine is http://shop.lenovo.com/us/itemdetail...E7BA925BCE90CA
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Last edited by HuttonIt; May 13, 2013 at 08:38 AM. Reason: add link
Old May 13, 2013, 08:54 AM
Mobius Cables... I got em'
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United States, TN, Oak Ridge
Joined Dec 2011
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oh... ok, and that one is 11.1v already...

Did the quick math and that is only 3400mah cells... the panasonics here are still better per weight, and price.
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Old May 13, 2013, 04:18 PM
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The Netherlands
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Ferdinand,

Since you have shown to have a very good knowledge and understanding of motor and prop efficiency, I was wondering what your opinion is on flight time when you compare quads with tri's. I assume you would have to find another optimal motor/prop combi to get long flight times on tri's anyway, but considering both have their optimal motor/prop combi, which theoretically has an advantage over the other when it comes to flight times?

Tri: extra weight per motor because of servo, but would probably be compensated by needing one arm less? Advantage might be total weight is less because it has one motor less to lift?

Also I would like to ask you if you could give some more insight in how you get to your highly optimized combinations. I've read in other posts you do some math, but are you just relying on calculators like ecalc or did you really dig into the electrical motor theory and math so you can make your own calculations to get to the most optimal setup?
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Old May 13, 2013, 09:39 PM
Mobius Cables... I got em'
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United States, TN, Oak Ridge
Joined Dec 2011
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If you compare the two, they basically would be the same weight.

Quad has 4 motors and 4 arms

Tri has 3 motors and 3 arms, then it has a pivot system and servo that can quickly equal the weight of the 4th motor and esc.

For efficiency it only has 3 motors to create lift so they either have to be bigger or have more stress to lift the same weight frame.

Basically Tri Vs. Quad is all in flying style... If you want a more "fluid" feeling then fly a tri, if you want a more precise "machine" feel then fly a quad. oh... and dont try to yaw a quad in a freefall dive
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Old May 14, 2013, 10:21 AM
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Joined Apr 2013
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You need to put something together and sell it. I'd love to be able to fly my quad for more than 12 minutes.
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Old May 14, 2013, 02:21 PM
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Austria, Niederösterr., Eggenburg
Joined Jan 2010
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@harmendejong
in theory a tri would be the better choice, since the frame can be build more lightweight than for a quad (arms are also shorter for the same prop size), but in practice, if you keep the distance of the motors from the center as low as possible there is not much space in the center left, and of course the mechanics for the moveable motor adds up in weight.

A quad is just simpler, 4 motors, no moving parts except the bells with the props ...

My math is just a simple excel sheet, based on a formula described here:
http://www.flugst0ff.de/copterflugzeiten-berechnen/
The missing parameter the "overall efficiency" has to be determinded (e.g. by one flight measuring the AUW, the flighttime and the mAh recharged). Then the formula matches the reality quite good. I have attached an exel-sheet, please just enter the data of your copter into one line. At "capacity" it is important to enter the value you recharged (not that what is printed on the label).

@Skumbag
The secret behind is not the components used, it is just that you start to bring the flighttime in your focus, than you will start to do the right modifications (lightweight frame, big props, more battery on the copter...). You can build clean (e.g. motor wires in the arms, nice landing legs, FC-protection dome) or you can build lightweight.

best regards

Ferdinand
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Old May 14, 2013, 02:45 PM
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Thnx for sharing this information! Since I am facinated by your achievements, I will definately digg into this (my German is not excellent, but with some help of the dictionary for the complex words, I think I can understand it quite well ).

From looking at your video's the quad seems a bit 'sluggish', meaning it does not appear to raise in altitude very fast and it seems to react a bit slow on ellevator and aileron input. Is this because at a lower KV and thereby lower rpm, the motors have less delta in terms of rpm available to actually react on your stick input, or is this just a wrong perception of me.

Also I was wondering if you were providing full throttle in your videos somewhere?
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Old May 14, 2013, 03:11 PM
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Long flighttimes and "full throttle" is a contradiction. Also there are no "sharp" stick commands from my side, this is not a copter for aerobatics.

I terms of agility this is the best I can offer. (Quad with 850gr battery, 130gr FPV and 570gr BL-Gimbal.

12mm Frame Quad big with BL-Gimbal (4 min 32 sec)


best regards

Ferdinand
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Old May 17, 2013, 06:34 AM
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Russian Federation, Samarskaya oblast, Samara
Joined May 2013
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@Ferdinand
What if build full power system for copter with Panasonic 2C battery + hight discharge battery with same 3400mAh but 40C?
What will happen then?
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Old May 17, 2013, 06:56 AM
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@konor,

I am not sure if I understand the question.

If you use one high capacity battery (low discharge rage) together with a high discharge rate battery (low capacity per weight), on this copter the only thing happening is, that the overall flighttime drops since the battery with the high discharge rate is more heavy (having identical capa).

If your question targets the use on a "normal" copter with lower flight-time, the answer is, that is will not help much. The "high-discharge" battery will work as a buffer, covering peak loads, but unfortunately the discharge curves are different between LiPos and LiIons, so you cannot use them together in parallel. The Lipos will already be dead (3.0V a cell under load) whereas the LiIons still provide power (2,5V a cell under load).

best regards

Ferdinand
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Old May 25, 2013, 04:14 PM
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Here again a video with the 12mm quad and the BL Gimbal with the Sony CX250. The achieved flight-time was 38min:
Freundschaftsfliegen MFC Pulkautal (5 min 24 sec)


best regards

Ferdinand
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Old May 25, 2013, 05:27 PM
CrashMaster
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United Kingdom, Brentwood
Joined Dec 2012
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how about these - http://www.batteryspace.com/High-Pow...ate-111Wh.aspx
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Old May 26, 2013, 12:49 AM
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Romania, Dolj, Craiova
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110Wh, 650 grams, $130... nothing unusual, this is 170Wh/kg, this thread battery has more 264Wh/kg.
The above can be achieved as well using two of these:
http://www.hobbyking.com/hobbyking/s...Boat_Pack.html
The resulting combo is:
100Wh, 576 grams, $116 ... 173Wh/kg

To have a better idea how much weight effective is the solution of endofdays, if trying use LiPo to reproduce you need four of these:
http://www.hobbyking.com/hobbyking/s...Boat_Pack.html
and combine them 2s2p, ending with a close 13200mAh capacity 4s, but 1100grams instead 770 grams.
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Last edited by renatoa; May 26, 2013 at 07:58 AM.
Old May 26, 2013, 07:19 AM
Alicante, Espańa
Joined Jun 2010
379 Posts
66 minutes, 30 seconds

This week I made a flight of 66 minutes and 30 seconds using this batteries. But my Idea is a little different. I want to flight long time to make FPV. So I have use a complitely functional QUAD. The TAROT quad. I made a battery using 24 of this 3,4volts Li-Ion batteries. Following the instructions of End_of_days. So I have a pack of 20 Amps, with a weight of 1240 grams. I can go to 40 Amps maximun of consuption (2c) in case I find strong winds during flight. But I can flight with 17-21 Amps including 200 grams of FPV ( the 66,5 min were without the FPV). My quad weight is 1350 grams, without the battery and the FPV.

I am using a 18 carbon fiber propellers, and Multistar 4822 490RPM motor.
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Last edited by catamar; May 26, 2013 at 07:27 AM.
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