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107G weight reduction
My attempt to reduce weight on my 107G so I can put a larger battery on it :-)
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Syma Freak
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December 16, 2012 - 11:04 pm
Member Since: November 26, 2010
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Yooo -I love these posts -just live life to the max-We have just got a huge wind in Sydney-windows all closed.no draft .I am flying the 302 mad yes i am!!!!!!!!!!

"Fly like a butterfly sting like a Syma" http://syma107.com

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Helgi Rudd
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December 14, 2012 - 10:52 pm

Absolutely, best time ever to be alive! :-)  When reading your reply I remember now having seen a video of someone starting their car with a model airplane battery... the energy density is frightening o_O  (i'll be extra careful if I do put two LiPo's in parallel... exact voltage match and outdoors with gloves just in case lol)

Good idea, lets stay alive for at least the next ten years... it's just starting to come together!
 

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Syma Freak
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December 14, 2012 - 10:04 pm
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Is it not a great time to be alive? just to think some years ago with my first mobile phone the size was like a car battery, now you can kick start a car with a 2200 mah battery-done that-where does the next 10 years only go to-hope I stay alive- lol

"Fly like a butterfly sting like a Syma" http://syma107.com

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Helgi Rudd
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December 14, 2012 - 9:45 pm

Thank you! I should have taken a picture of the cardboard rig I taped onto my hat to video it, it was some serious hobo-film-equipment action :-)

 

They really do an incredible job those motors... I am so amazed with the technology overall... I've been into pulling things apart since I was 10 and I'm mid thirties now... 10 years ago I wouldn't have believed it if you'd told me a little thing could be built and sold for $25... in fact I wouldn't have thought it possible at all!!!

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Syma Freak
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December 14, 2012 - 8:06 pm
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I always love the sound of the Syma 107 motors kicking in-good videos-always hard to capture the flight-you did it well-Great stuff ! Laugh

"Fly like a butterfly sting like a Syma" http://syma107.com

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Helgi Rudd
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December 14, 2012 - 4:51 pm

Better video... strapped my phone to my hat  lol

Can really see how much it can be thrown around with 12 grams stripped off!

 


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Helgi Rudd
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December 14, 2012 - 2:26 pm

 

Video of the current setup. I rigged up a temporary battery holder so I can still fly while waiting for delivery of new batteries.

 


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Helgi Rudd
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December 9, 2012 - 7:39 pm

I'm going to heed that advice and leave the balance bar for the moment... although I've ordered a 'spare parts pack' that includes a balance bar, maybe I'll have a play when I've got that spare.

 

Maybe that plastic wasn't PVC, I did a little bit of Googling to try and work out what plastic is used for those plastic cards and PVC came up the likely match... it was strong, but very brittle, after another flight and a few crashes the cradle I spent so long building was in pieces.

 

I completely rebuilt the cradle from the new plastic I decided was suitable. I've seen it a couple of times before, not sure what it is, but it's strong but also flexible enough that it's quite impact resistant... and bendable without snapping. It's worked out a treat.

 

Here's a picture of the plastic I'm using... note the sparkly effect, a giveaway I suspect if one knows their plastics.

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Here's the cradle in fabrication... to make the two side pieces match perfectly I put a very very thin layer of blue-tac between the two sheets of plastic so that I could dremel them at the same time. Very low tolerances here with regards to the location of the screws... spend the time to get them perfect, then cut roughly in the shape needed... whittle away the plastic with a dremel tool, I started with at least four times the volume of plastic seen in the picture below.

 

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 Here's the final assembly. So so so fiddly doing the second gluing, nail biting after hours of fabrication.... really didn't want to stuff it up!

 

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I have also modified the tail boom... the carbon fiber rod I bought was an exact fit INSIDE the original metal rod... so, I sliced the ends off the metal rod so I could use them with all the important locator slices and holes they have in them... then put my hollow carbon fiber rod in between.

 

Couldn't help making the new tail boom a little bit longer... not much, but gives a little bit more power re: the level principle.

 

I slapped together a makeshift battery holder... need some weight out the front there.

 

It flies quite well... it's very 'touchy', have to be careful not to end up coming out of a turn at ridiculous speed... and hitting a wall. Crashed a dozen times testing the flight properties... AND, the new cradle took it all like a boss!

 

I'm not happy with the weight distribution... but that will all change when I get those two new 240mAh batteries, I would like to strap them either side of the core, keep the weight as close as possible to the center of gravity. I will need to have them slightly forward of center to counter the tail weight but with two 240mAh batteries I won't need to have them forward anywhere near as much.

 

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CPD
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December 8, 2012 - 2:32 am

I don't think removing or modifying the balance bar's a good idea. I know with the old ones you could cut them down by 1/3 and they would still fly, but when you're flying suck a light and fast bird, you need the balance bar to do its job, no questions asked. It also seems like the newer balance bars are cheaper, with just weights shoved into plastic, which wouldn't be good for modifying anyway.

 

Basically, when you make any sort of manuver, and your BB isn't fully up to the job, you'll knock it right out of the sky. You can try if you want, but I'd say better safe than sorry.

 

I'm suprised to hear the PVC doesn't hold up. I would have thought it to have been a very good lightweight material for this. Hmm... Wonder why...

 

I guess the best case scenario would be carbon fibre, but that's kinda expensive because of how much resin you have to buy at a time. Especially when you don't know what your doing to make it into parts!

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Helgi Rudd
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December 7, 2012 - 11:45 pm

Love the idea of drilling holes in the gears... I'm not competent enough to do that right now, but it's a brilliant idea... so many parts are over engineered, a few holes in the right places would reduce weight without reducing critical strength at all. Hmmm... rotational energy in the spinning parts too, making those gears as light as possible seems like a great idea!

 

I put my modified copter into play tonight... had some fun outdoors with a bit of a crowd gathering wondering what on earth this tiny flying thing was! Flying close to power lines was fun, it's amazing how high it can go... limited very much by the psychology of flying something that's infra red controlled... I'm very much tempted to do the radio frequency mod on the web page I linked above... VERY much tempted... I want a light weight radio frequency version... if the best that is available is the website I linked above then I'll go for it... I reckon I can trim down that receiver circuit board to less than a couple of grams.

 

I have to say... PVC is not the right material to work with. I've broken bits off the parts I've fabricated in posts above, left right and center. It's too brittle at this scale. I have an alternative plastic I'm going to work with next... it's very dense, but very flexible and... well, it just 'feels' like the right thing to use... I will try my best to identify it, as I think this one is going to be the one to work with for parts that are structurally important.

 

I replaced the stock tail boom with the carbon fiber tubing I bought. By chance as much as anything else the CF tube I bought fit perfectly inside the stock metal tubing... when I say fit, I mean that it fit to within a few hundredths of a millimeter. I sliced three quarters of an inch of the stock metal tail boom from either end... so I have all the fancy connector bits ready to go (like the groove in the original metal that fits perfectly into each end of the receiving plastic bits).

 

So I replaced the stock metal boom with a carbon fiber boom that is longer.... it weighs LESS than the original boom but is longer... and by the leverage principal it gives better forward and backward movement.... i.e. something giving thrust further out than originally when connected by a lever (aka the tail boom) is going to give faster forward and backward movement.

 

In the picture below you can see I've rigged up a makeshift battery support... so I can give some temporary weight to the front end, until I get my two battery packs that I'll place either side of the mid section.

 

I am playing a waiting game on battery delivery now... tempted to remove weight from the balance bar weights.

 

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CPD
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December 7, 2012 - 3:15 pm

Wonder if there's carbon fibre tubes you could get that would be a close enough match for the main shafts that you could swap them out... Probably could shave off a few more grams, and probably could drill small, well-aligned holes in the gears too. You would just have to make sure they were PERFECTLY aligned so it wouldn't be the slightest bit unbalanced. You could probably shave down where the tail boom goes into the corpus if you decide to cement it in there instead of screwing it too.

 

If I had the time, a dremel and a heli to spare, (well, ok, it wouldn't be spared) I would have to try this out sometime... For now, I have a friday, kinda sorta have a weekend, then finals week... Oh dear...  Not gonna be fun...

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Helgi Rudd
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December 7, 2012 - 2:17 pm

Dremel's are fun aren't they!?  I've been missing out all these years! 

 

I've whittled away what I'm able to (with my total of half an hour Dremel experience lol) from my PVC parts...

 

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With the six screws needed, they come in at 0.83g... the screws make up 0.29g of that.

 

The PVC is quite strong, with better Dremel skills I could take it a bit further.... but I'm happy with this setup for the moment. The electronics board sits nice and snugly on that flat bar... I've removed areas where chip resistors / capacitors were in the way... so it's nice and flat on the remaining surface. The other PVC part comes down and sits snugly on top of the circuit board so it's well enough supported.

 

The picture below is of my current 'bare bones' 107G... it weighs in at 26.08g... with the above PVC parts attached so it can actually take off, that's a grand total of 26.08 + 0.83 = 26.92g

I haven't touched the weights in the balance bar... or replaced the tail boom with carbon fibre rod... but I suspect that people saying they can get their setup to just over 20g are cheekily weighing without the battery... maybe not though... we'll see soon enough.

 

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Next job, cleaning the soldering iron with the dremel tool and breaking out the carbon fibre rod!!!

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Helgi Rudd
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December 7, 2012 - 1:44 pm

That would be brilliant if you could pull it off! I want to see record breaking flight times :-)

On the topic of the C rating... I wonder if the cell phone battery would be able to handle the current discharge needed? Apparently the last thing you want is an exploding LiPo battery... it's meant to be spectacular!

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zedorda
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December 7, 2012 - 1:01 pm

I am also tossing around the idea in my head of maybe using some of my old cell phone batteries. I have one that is 840mAh at 19g. Yes it is on the heavy side but there seems to be enough weight to remove to make it possible. The flight time could be 40+ mins but the charge time would suck.

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Helgi Rudd
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December 7, 2012 - 12:39 pm

The C rate defines how much current can be drawn... too high is not a problem, too low is though.

 

You can work out how much the maximum current is with the following formula:
 
C Rating x mAh / 1000... so for that 350mAh rated at 25C you can pull a maximum of 350 x 25 / 1000 = 8.75 amps... they advertise 8 amps which is probably a good thing since you wouldn't want to go right up to the limits.

 

No idea how much current the 107 pulls... could roughly work it out from flight time I suppose...

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Helgi Rudd
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December 7, 2012 - 12:25 pm

As promised, here is an image showing various parts you could remove and their weights.

 

Note the pile of 5 screws in the top right... these belong somewhere in the mix (I'm using them to attach my custom bits of PVC)... but you're getting a fairly accurate idea of where the weight lies from this image.

 

If you added a battery that was 3g heavier than the stock you could simply remove the nose cone and you're up and running... if you could make a super lightweight replacement nose cone weighing about a third of a gram all the better. Lots of ways to reduce weight to compensate for adding weight on in other ways!

 

Note that my version has the small weight in the nose cone... and the LED is in the nosecone I've removed as well.

 

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zedorda
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December 7, 2012 - 12:20 pm

This is one I am considering but not sure if 25C is too much current.

 

http://www.cheapbatterypacks.c.....-Pack.aspx

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CPD
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December 7, 2012 - 4:27 am

zedorda said
Thanks for posting this project it has been very informative. I was thinking of doing something similar but not as extensive. I want to add a 350mAh plus plugs to enable battery swapping. I also intend to mount the battery between the skids and I am perfectly ok with adding some additional grams but not sure how much to allow yet.

Have you considered using balsa wood maybe treated/painted with something to increase surface hardness?

I've worked a lot with balsa--good, cheap, easy to work. If you coat it with simple white glue, it becomes a LOT harder, but it's still too soft for these things. The big problem is that the screws and whatnot on the heli aren't that long, and balsa's too thick. Plus, styrene sheeting costs about as much, if not less, and is just as easy, if not easier to work with. (plus, when you do something with balsa, I've had a tendacy to notice it doesn't look very "professional" while anybody with the right stuff can make styrene look half decent.)

 

The only downside I've seen to styrene yet for anything is the glue you have to use for it comes in a jar that is VERY easy to knock over. Not good when you spill half of a $3.79 jar of cement all over the basement floor... (it's thinner than water and runs VERY easilly.) I bought a dollar tree stone candle holder for mine, about the perfect size, and nice and heavy to keep the bottle from getting knocked over.

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Helgi Rudd
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December 6, 2012 - 10:11 pm

No worries at all zedorda... I'm having heaps of fun with it already, happy to post anything that might help.

What I'll do tomorrow is weigh each part separately and put together the weight saving for each weight saving step... for example how much weight is saved by just removing the canopy and nothing else... or perhaps just removing the tail supports... or by removing the metal plates in the guts of the middle etc. etc.

I'm also interested in cataloging a reliable reference for battery weights... I find so much inconsistency when looking at the various battery sizes (150mAh, 240mAh, 350mAh... etc.)  I'm hoping to end up with a formula which takes into consideration power and weight variables to identify the best market battery available for longest possible fly time.

If you just replace the stock 150mAh with the 350mAh and add plugs etc. without removing some weight I think you might be stressing the motors a bit beyond the reasonable. Without having an idea of how much the 350mAh battery weighs it's hard to know what you might need to remove to get a nice stable setup. Hopefully the table of part weights I'll put together tomorrow will give an easy way to assess the options if you do know the battery weight!

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zedorda
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December 6, 2012 - 4:38 pm

Thanks for posting this project it has been very informative. I was thinking of doing something similar but not as extensive. I want to add a 350mAh plus plugs to enable battery swapping. I also intend to mount the battery between the skids and I am perfectly ok with adding some additional grams but not sure how much to allow yet.

 

Have you considered using balsa wood maybe treated/painted with something to increase surface hardness?

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