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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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Helgi Rudd
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December 6, 2012 - 10:51 am

Love the idea of the glue that 'welds' it together... sounds toxic, but fun!!! :-)

I'm planning on trimming down that cradle I've made to see how much I can reduce the weight while still keeping strength... I haven't received the dremel tool I ordered yet and I'm thinking I'll need a fair bit of practice before tackling anything worthwhile. That Polystyrene sounds perfect for making a very lightweight 'shell' for the helicopter... I've spent a fair bit on equipment already... I can see this being an expensive hobby, but hey, that's what makes working for $ worthwhile right?

 

I have some scales now! Just came in today... I've weighed a few things:

 

- Parts removed = 12.88g

- Current helicopter, including the plastic PVC bits I've added = 27.63g

 

Looks like I've already taken off enough to be able to replace the stock 150mAh battery with TWO 240mAh batteries and still be under stock weight!

I also taken delivery of a long piece of carbon fibre rod... intending on replacing the tail boom with that... once I get hold of that dremel tool :-)

When I was younger and tinkering around with electronics I didn't have access to 'breadboards'... lived in a remote area and we were quite poor... so I soldered my circuits without an board... I called it three dimensional soldering... I would end up with balls of circuitry... they worked though and were much lighter without the board obviously. Crazy thoughts of getting the 107 circuit diagram and doing some three dimensional soldering to reduce even more weight! Would have to practice my soldering skills... a LOT... ha ha, those little chip resistors / capacitors are fiddly enough on a circuit board!

 

Also got excited reading through a webpage showing in a fair amount of detail how to replace the infra red with radio control. I've never had an excuse to own a oscilloscope... this might be my chance!  http://www.brasswings.com/rcsyma.html

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CPD
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December 3, 2012 - 4:47 pm

Yeah, depending on what your hobby shop does. None of the ones near me carry it, so I either have to go about an hour away if I wanted some or buy it online. (well, ok, I have a train shop by home and a train shop up by where I'm going to college, the hobby shop closed about 2006 because they weren't doing THAT great of buisness and the guy wanted to retire)

 

It's a low density plastic, and you use specialty glue on it that melts it, then welds it together. Very strong bond for models, and decent for these. One thing I like and would recomend, is save your little shavings and bits of scrap somewhere, because if you get a gap in your parts from a cut not being straight or need a slight shim, you can take the shavings, add a fair bit of cement to the joint and they will basically become plastic brazing.

 

There are two main companies that produce it, Plastruct and Evergreen Plastics. I would go the route of Evergreen Plastics, they're MUCH cheaper than plastruct for the same material. The only thing I would use plastruct for is some of their bulk sheeting is VERY cheap, and they have a lot more specialty stuff for modeling, like ladders, translucents, etc. You don't need too thick, since these are just little guys and not landing too hard, but since your design calls for a solid frame, including skids, you need thicker than I would otherwise recomend. I would go maybe max of 1/16 (0.0625") of an inch, min of 1/32 (0.03125") of an inch. The standard is to sell it by decimal inch/decimal cm, so you'll have to remember the decimal number. I would also say it might be worth a shot to try to laminate thinner sheets, where you can have very thin at the very top, and put just the right amount of added structure where called for. (although thicker sheets can be trimmed to be thinner with a razor/X-actor knife.)

 

http://www.hobbylinc.com/htm/p.....s91104.htm That's where I got my stuff from before, and that's about the right thickness I would recomend for something like this. (maybe a little more, maybe a little less) Their bulk packs are VERY reasonable, especially compaired to everything else by plastruct. I would also get some angle styrene to re-enforce joints and whatnot.

 

Anyway, it's VERY easy to work with, lightweight, cheap (if you buy the right stuff) and quite durable. Nowhere close to credit card plastic durable, but it gives some, and doesn't break, just bends. I wouldn't be suprised if the plastic on the military heli bodies are some sort of polystyrene.

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Helgi Rudd
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December 3, 2012 - 10:30 am

Polystyrene sounds great... do you buy that in sheets from a hobby store?

When I get some scales I'll be able to work out what the weight limits are... but if the stock 150mAh battery is 4g and the 240mAh is 5.6g then I need to remove only (2 x 5.6) - 4 = 7.2g  (I made a mistake in my previous calculation... forgot to subtract the weight of the stock battery I'm planning on removing).

I've come across posts on the internet of people getting the weight down to just over 18g (less than HALF the stock weight)... I only saw a picture of just over 20g though.

The stock weight is about 38g... so I would only need to get it down to 38 - 7.2 = 30.8g to end up with a version that has the same original weight but with 480mAh instead of 150mAh.

Replacing the blades seems like a great idea to me! I only have this 107G and a really bad rip-off version that inspired me to find something that actually flies properly! (hence I'm here playing around with 107G's :-) )

When I did that hover test I was surprise how cool the motors were at the end of it... I could barely detect any heat at all... would struggle to call them warm let alone hot.

Can't weight to get those scales... miss-spelling pun intended ;-)

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CPD
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December 3, 2012 - 5:52 am

Looks good. PVC's a good, strong material to use. Personally, I'm used to using Polystyrene that you get for modeling buildings, but that sounds like a good material to use. I wouldn't be suprised if it still is too heavy with two 240mah batteries, though. These little guys seem like they have a fair bit of lift, but they really don't.

Somebody really should try to find if there's any blades that will work on these things that have more lift. These blades are alright for a stock heli, but if you want to have anything heavier than stock, they're no good. (like if you want to put the guts of the heli into a plastic model of a different real heli)

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Helgi Rudd
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December 2, 2012 - 6:11 pm

I've built a rudimentary 'cradle' for the PC board... which also has legs to protect the bottom and allow landings.

When I get the Dremel tool I'm going to lighten this cradle significantly... still working with the 'credit card' plastic, which is PVC... one of the heavier plastics... it's very sturdy though... I'm planning on thinning the parts I've fabricated with the Dremel tool.

 

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Here's a picture of it all put together... for the moment I've just sticky taped the battery on the front.

 

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It looks a bit like a dragon fly :-)

Hover test at about 5 feet gave 11.5 minutes fly time. Still on the stock battery so pretty happy with that.

In this configuration it creeps backwards slowly... so it's tail heavy. I've ordered some carbon fibre tubing which will lighten up the tail end.

Still planning on strapping 240mAh batteries (wired in parallel) onto either side of the body.

It flys brilliantly still... very responsive and accurate.

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Helgi Rudd
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December 1, 2012 - 6:30 pm

Thanks for that link Syma Freak... so many amazing mods in there... getting into the guts of the electronics is some next level stuff, incredible!

Cheers CPD, I'm going to carefully put a tiny drop of super glue to hold the motors in place... since I've taken the top bracket off one of the motors has already popped out once! I'm still deciding what to do with the circuit board and battery after my recent modification (below). I had a thought about the battery... I have already ordered a few from eBay (which won't arrive for a while yet)... one order I placed was for two 150mAh batteries... I thought maybe what I could do is hook them up in parallel and place one either side of the core body... not at the front at all. I suppose with all the weight reductions I'm making I'll have to play with the weight balance.

I've had a go at modifying the undercarriage, quite pleased with the results so far. It seemed to me the main importance was to keep the original functionality provided by the black plastic 'tray' that the circuit board was mounted on... the part that the rotor spindle (terminology!? lol) drops into... it stops it from dropping down too far and the gear slipping below the drive gear.

 

Image Enlarger

 

In the picture you can see the white plastic replacement I've installed... and in the foreground my first failed attempt

I'm awaiting delivery of a dremel tool to make life a bit easier, at the moment I'm working with a swiss army knife (I love the hole borer on it, I've drilled through all sorts of things with that!).

Anyway, this modification means I can do away with the remaining aluminium side plates, and the plastic tray underneath.

Next I'll decide what to do with the circuit board and the battery... and maybe add a few 'crash protection' features ;-)

For this modification I took a plastic card... like the plastic cards that go in a wallet. I carefully sliced a long even strip, then drilled a hole in the middle that was just the right fit for the protruding metal rotor spindle. From the middle of the center hole I lightly scored at 7mm on both sides then carefully bent in the direction away from the scores. The plastic sort of splits a bit when bent but there's a strong enough connection to finish the job and strengthen the bend at the end. Next I measured 30mm from the center hole in both directions and drilled the holes for the screws to go in. After screwing in I very carefully applied the smallest amount of super glue to the 90 degree bends... nice and strong.

There are other screw holes available on the mast, potential to save a tiny bit more weight, but without proper tools this was the best I could do.

edit: researching battery weights... I don't have scales to weigh, but eBay searching reveals 4.0g for 150mAh, 5.6g for the 240mAh batteries I have already bought... and 15g for 500mAh.  My gut feeling at the moment is that 2 x 240mAh batteries is going to be the way to go... then I can place one either side and have much more freedom to adjust weight balance. Pretty sure I can remove 11.2g of weight.... if I do that then I'll have the original stock weight but with 480mAh instead of 150mAh... more than three times the flight time!

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CPD
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December 1, 2012 - 2:28 am

Just a few quick tips--make sure when you add the larger battery that wou add some weight to the rear of it so it's not too awefully nose heavy, or it'll just be a bullet and ram into your walls, and do something to hold the motors in place. The original frames have little tangs that hold them down, but if you don't have the upper frame on there, they can just pop out. (and trust me, that's not good at all to be flying, and have a motor just pop out of place)

 

Hope you have good luck with that! Keep us in touch!

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Syma Freak
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November 30, 2012 - 6:05 pm
Member Since: November 26, 2010
Forum Posts: 1452
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Good post and neat photos-CPD is always worth touching base with and Raptor as they are into lots of mods -link here http://syma107.com/forum/gener.....ndom-mods/

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

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Helgi Rudd
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November 30, 2012 - 4:52 pm

I recently bought a 107G... so much fun out of the box, but I couldn't help starting the process of modifying it, with the aim to reduce weight so I can replace the stock battery with a larger one!

 

Here's what it looks like so far.... ugly, but it fly's really well (so far). I've had quite a few crashes and it's still going strong.

Image Enlarger

 

These are the parts I've removed so far...

Image Enlarger

 

I'm planning on doing some more weight trimming:

  • Replace the remaining two aluminium plates with X shaped plastic supports I'm going to make from plastic similar to credit card plastic... minimal volume of plastic... just a simple X brace with the four screw holes.
  • Remove as much plastic from the black plastic 'tray' that the circuit board rests on.
  • Maybe attempt to reduce the weight in the gyro stabilizer

Hopefully I can put a 240mAh battery in a get a decent fly time :-)

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