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Old Apr 16, 2012, 07:23 AM
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Need help with getting the smallest and lightweightest possible setup for an orni

Hey all, im trying to make an easy mod, basically im trying to mod a wowwee dragonfly like ornithopter (its 2 channels) electronics as im sick of glitches and range below 30 meeters... i have a spektrum dx7s so i wanna base the setup on that.
Currently im a newb at this so i do not understand the required hardware to make 2 simple motors running, all i know is that i need battery, a receiver and transmitter, since i already have a spektrum dx7s the smallest and lightest i could find was AR6300 (which i didnt buy yet).

So, what exactly do i need to make a 2 channel setup work with my dx7s and keep it as light as possible? also is brushless motor out of this league? the smallest ones are far to big for this ornithopter? what else is needed besides the tx/rx battery and motors?

Thanks a bunch for all your help!
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Old Apr 17, 2012, 04:57 PM
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Can you post a picture and the weight of the ornithopter?
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Old Apr 17, 2012, 05:49 PM
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Can you post a picture and the weight of the ornithopter?
Hey, thanks for the reply here is the link:
http://www.wowwee.com/en/products/to...reen-skyhopper

Never mind the fitting process ill think about that after i get the setup, i was suggested a AR6400 as it has everything including 2 micro servos but i dont know if its allright to take out the linear servo mechanism or whatever its called and use the motors for throtle and 1 for steering (the steering is done with a small rotor on its tail like a helicopter).

But as ive said, im looking for someone experienced at this to help me out figure if its possible or not to get the lowest weight possibly hobby grade electornics to bind it to my dx7s & to get more performance if possible too xD

Specs:
WingSpan: 15 (38cm)
Weight: around 25 grams but i will double check it tomorrow.
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Old Apr 18, 2012, 11:39 AM
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Take a look at this; http://www.hobbyking.com/hobbyking/s...dProduct=17636

Pretty sure it'll work.

I recently used a couple of these for direction control of a mini zeppelin; open it up, throw out the gearbox and use the motor and the electronics as a left/right 2 speed speedcontroller.

Dirk.
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Last edited by swami; Apr 18, 2012 at 11:44 AM. Reason: added more info
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Old Apr 19, 2012, 08:47 PM
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Swami makes a good point but you may want to use a bigger servo if your tail motor is not the same size as the one in the 1.7 servo otherwise you may risk overheating the electronics in it. I found this receiver that weights 2 grams (1.9 grams lighter than a ar6400) that will work. Plug in the servo electronics to reciever and solder the tail motor to the electronics. You will also need a ESC to use the motor in the ornithopter and some plugs and wire to connect the ESC to a battery and some heatshrink to insulate them.

I recommend you buy lots of this stuff in case you break something on your first try (it's cheap anyhow).

Judging by the weight and wingspan the ornithopter uses a 7mm pager motor or something equivalent. I don't know of any RC store that sells a brushless motor that size but the closest higher performance motors that I know of are the 8mm pager motors or the 10mm brushless inrunners. The flapping mechanism of the ornithopter would most likely have to be modified and they may overloaded it causing it to break. If you want better performance the easiest solution is to decrease the weight of the ornithopter. Taking off the insect body might be enough to satisfy you.
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Old Apr 20, 2012, 12:03 PM
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im very sorry i forgot to mention i live in europe, i cant order that because in the end ill pay outrageous fees just to get it on my hands and wait at least 1 full month for it to arrive.
Thank you very much though it does sound like an ideal product.

Btw this should be 2 motors running, just the motors alone, no servo mechanism no nothing, imagine 2 throtle motors.

As for performance, its something i would want thats true, however not a requirement, the main result i want is to be able to bind it to my transmitter and fly it with it, having brushless motors so it wont need a replacement anytime soon is something i would really want aswell but again not an entire requirement.

Thank you very much for both of your help and very detailed information.

EDIT: btw what is the diference between a pager motor and a normal burshed motor?
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Old Apr 21, 2012, 01:21 PM
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This article explains the difference between pager motors and common brushed motors.

Some pager motors will run for a long time if left to cool after they're used. If you want to buy spare pager motors here is a list of places that sell them. I've bought from Plantaco and BSDmicrorc and they have a large selection.
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Old Apr 22, 2012, 03:17 AM
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[QUOTE=Legendary_Agent;21387013]im very sorry i forgot to mention i live in europe, i cant order that because in the end ill pay outrageous fees just to get it on my hands and wait at least 1 full month for it to arrive.

Legendary , one of the Hobby King's warehouses is located in Germany.
To the best of my knowledge both ,Germany and Portugal are members of EU . So you don't have to pay any duties if you buy from them.Just make sure that the desirable product is available in the European warehouse .Also just for example the shipping costs from there to US was about 12 US$ for small 200 grams package and it take about 10 -12 days to arrive to US. As Portugal is closer to Germany I hope the shipping costs will be lower and the delivery will be faster but this logic doesn't work every time.They have a large variety of RC stuff including micro and very low prices.
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Old Apr 22, 2012, 09:23 AM
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have you thought of improving the transmitter or extending the rx antenna with magnet wire?works for my toy stuff before i take them apart
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Old Apr 22, 2012, 03:28 PM
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[QUOTE=seagull10;21401410]
Quote:
Originally Posted by Legendary_Agent View Post
im very sorry i forgot to mention i live in europe, i cant order that because in the end ill pay outrageous fees just to get it on my hands and wait at least 1 full month for it to arrive.

Legendary , one of the Hobby King's warehouses is located in Germany.
To the best of my knowledge both ,Germany and Portugal are members of EU . So you don't have to pay any duties if you buy from them.Just make sure that the desirable product is available in the European warehouse .Also just for example the shipping costs from there to US was about 12 US$ for small 200 grams package and it take about 10 -12 days to arrive to US. As Portugal is closer to Germany I hope the shipping costs will be lower and the delivery will be faster but this logic doesn't work every time.They have a large variety of RC stuff including micro and very low prices.
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if you check the tx/rx section of european warehouse you will only see 1 receiver and 1 transmitter
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Old Apr 22, 2012, 03:33 PM
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have you thought of improving the transmitter or extending the rx antenna with magnet wire?works for my toy stuff before i take them apart
Im no electronic expert, infact im 0, all i know is to solder the right pieces in the right places and thats kinda it...

Also thanks a bunch for showing me that pager motor reference! So if i understand correctly, they last longer than normal brushed motors, they are made to be very small and very light and have a high efficiency of battery usage, so at a small scale a pager motor is far better than a "traditional" brushed motor, right?
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Old Apr 22, 2012, 03:39 PM
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What is magnet wire? is it a wire which when is electrified has magnetic properties?

This is interesting if i could increase its range without modding it, but i still think 2.4ghz rx with 2 brushless motors would be freaking awsome for this toy! if doable aka (not much heavier).
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Old Apr 23, 2012, 11:10 AM
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All wire will produce a magnetic field when you pass a current through it' depends on number of turns and type of current etc ac dc that is how motors and actuators work etc.
Magnet wire is generally the wire one would find in solenoids relays speakers etc.
It will be enamelled and need cleaning before you can solder it.
If you double the length of the rx antenna you should see an improvement.
Or trail a wire the same length as the tx antenna from the -ve of the tx board or battery etc.
Worth a go before you throw cash at it.
I do have a science museum hawk type thing I want to mod though so will be keeping an eye on this thread.
Cheers nick.
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Old Apr 24, 2012, 09:34 AM
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Originally Posted by ballores View Post
All wire will produce a magnetic field when you pass a current through it' depends on number of turns and type of current etc ac dc that is how motors and actuators work etc.
Magnet wire is generally the wire one would find in solenoids relays speakers etc.
It will be enamelled and need cleaning before you can solder it.
If you double the length of the rx antenna you should see an improvement.
Or trail a wire the same length as the tx antenna from the -ve of the tx board or battery etc.
Worth a go before you throw cash at it.
I do have a science museum hawk type thing I want to mod though so will be keeping an eye on this thread.
Cheers nick.
hmm i will see what i can do but im not 100% sure this will work, i get alot of annoying glitches between 3 buildings but the distance between each is above 20 meeters radius (from the middle), i will see what i can do about it, btw, is it possible to have 2 independant motors running like throtles? 1 throtle to make the flapping mechanism fly and another throtle to rotate a blade either positively or negatively to steer left and right, when i asked for 10mm brushless motors and the ar6300 the guy at the store told me that such thing is too hard to do and he has to think of a way to make it work because a spektrum transmitter only works with 1 throtle!?

Btw that flapping falcon does indeed look cool, it also uses a servo on its back rather than a throtle rotor so it will be a bit different on the steering part from mine.
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Old Apr 24, 2012, 12:53 PM
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Im no electronic expert, infact im 0, all i know is to solder the right pieces in the right places and thats kinda it...

Also thanks a bunch for showing me that pager motor reference! So if i understand correctly, they last longer than normal brushed motors, they are made to be very small and very light and have a high efficiency of battery usage, so at a small scale a pager motor is far better than a "traditional" brushed motor, right?
Pager motors are also called coreless motors and the efficiency increase comes from no eddy currents from a iron core. I remember reading the average pager motor is about 60% efficient (Note: The N20 and M20 have an iron core).

RC plane ESC's are unidirectional and you would need a bidirectional ESC for your ornithopter's tail. Plane ESC's are also sensorless so they'll accelerate a motor slower during startup than a brushed ESC with a brushed motor, so using a brushless motor would make the controls slightly delayed when the motor isn't turning. You could use a servo to control a rudder, that would outlive a tail motor but you would have less control when the ornithopter flies slowly.

You could also replace the tail motor with your own homemade brushless motor but then you would have to solve the problems stated above.
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