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Post by starboy on Jan 17, 2011 0:24:34 GMT 1
 One of the first modifications that SC owners often make is to the battery box. I've tried a few different solutions since I bought mine last year. This post is about my most recent attempt, which was intended to address the following requirements: - it must accommodate all of the typical battery sizes, from the stock 1300mAh to the huge 2200mAh.
- it should allow for quick installation and removal of the battery
- it must hold the battery at the CG
- it must be light weight and inexpensive
The basic concept is a spring suspension mechanism that automatically adjusts to the size of the battery. The springs are attached to a rectangular frame which is epoxied into the fuselage just inside the battery door, and hold the battery from all four sides, keeping it in the desired position, which is centered over the model's CG. The material I used was a 3/8" band saw blade, which cost about $10 at Home Depot. I think 1/4" would have been sufficient but I used what they had. The steel is springy, light weight and easily bent and machined using common Dremel tool bits. I cut three pieces to the desired lengths using a cutoff wheel and the teeth removed using a course grinding bit. I used sand paper to remove any remaining burrs. The pieces of the assembly are fastened together using 1/8" aluminum rivets. Since the material is only 0.012" thick, I had to sandwich two aluminum washers between the pieces to be joined in order to take up the slack for the 1/8" grip range of the rivet. To install the battery you simply push it down into the assembly. The springs will expand to hold the battery firmly, regardless of it's size. The length of the three pieces are as follows: - frame: 11.25"
- left-to-right spring: 11.5"
- front-to-back spring: 12.5"
One thing I added after uploading the images below, is a small strip of Velcro on each side of the frame which can be fastened over the battery once it's in place to hold it up and prevent it from crashing through the battery door during a hard landing. Images: s1100.photobucket.com/albums/g409/zaphod_for_president/Spring%20steel%20battery%20cage%20for%20Hobbyzone%20Super%20Cub/The bend lengths can be gotten from the first of the images which shows dimensions. |
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Post by john66 on Jan 17, 2011 14:41:42 GMT 1
Nice workmanship and design work, but dosent it way alot?
John
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Post by starboy on Jan 17, 2011 15:29:57 GMT 1
Nice workmanship and design work, but dosent it way alot? John Actually, no. It's extremely light. I forgot to put it on my scale before gluing it into the plane but you can barely feel it in the palm of your hand. The spring steel is extremely thin and the rivets and washers are almost nothing. It might be in the neighborhood of the original plastic battery box or a tad more. |
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Post by john66 on Jan 17, 2011 15:48:54 GMT 1
Nice workmanship and design work, but dosent it way alot? John Actually, no. It's extremely light. I forgot to put it on my scale before gluing it into the plane but you can barely feel it in the palm of your hand. The spring steel is extremely thin and the rivets and washers are almost nothing. It might be in the neighborhood of the original plastic battery box or a tad more. Wow thats great! Im considering fibre glassing the bottom of my plane where the Batt box screws in and also continuing it up the inside of the fuse compartment, simply for strength as my lolly stick strengthening mod didnt hold up very well. I understand this may add substantial weight but Im hoping my XYH 35-36 1100kv can cope with this and I can get away with balancing the cog with weight where neccasary (I have my ESC in the cowl as suggested by Nick (ginginho) so hopefully wont need too much extra. Once again, Nice work. John |
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Post by mebillica on Jan 17, 2011 16:08:25 GMT 1
Very Nice! You should patten it and sell it!
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Post by starboy on Jan 17, 2011 16:19:14 GMT 1
Im considering fibre glassing the bottom of my plane where the Batt box screws in and also continuing it up the inside of the fuse compartment, simply for strength as my lolly stick strengthening mod didnt hold up very well. I understand this may add substantial weight but Im hoping my XYH 35-36 1100kv can cope with this and I can get away with balancing the cog with weight where neccasary (I have my ESC in the cowl as suggested by Nick (ginginho) so hopefully wont need too much extra. Once again, Nice work. John The practical issue related to weight isn't so much whether or not your power system can handle it. The heavier the plane (per wing area) the higher it's stall speed. So not only will your landings be hotter you'll be at greater risk of stalling out during turns and such. To overcome the weakness you referred to with the battery hatch, I hollowed out a bit of the foam under the ends of the battery hatch using a soldering iron, and epoxied two small pieces of Delrin plastic into the space. The Delrin provides a very secure hold for the screws that hold the hatch in place. You can see the white painted plastic to the far right and left of the battery hatch in the image below. The rest of the hatch, and the landing gear, is still screwed to the topmost frame of the original battery box, which I did not remove. I only cut away the part of the box that extended down into the battery compartment and actually held the battery.  |
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Post by john66 on Jan 17, 2011 16:22:54 GMT 1
Nice workmanship and design work, but dosent it way alot? John I knew how to spell "Weigh" last time I looked!  John |
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Post by john66 on Jan 17, 2011 16:40:58 GMT 1
Thanks for the pics. Part the reason I wanted to glass the entire fuse internal hollow, was cos my last ahem, landing split the fuse down the side vertically!
John
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Post by starboy on Jan 17, 2011 17:00:11 GMT 1
Thanks for the pics. Part the reason I wanted to glass the entire fuse internal hollow, was cos my last ahem, landing split the fuse down the side vertically! John Gotcha. Gravity is a biatch. I've often wondered how I will deal with the eventual major structural failure. I guess I always kind of assumed epoxy would serve to hold the pieces back together while wrapping the entire weakened area in box tape would sufficiently re-enforce it. Although I've done a few lawn dart imitations myself, for some reason nothing besides a prop has ever been damaged (besides my pride).  (Edit: The obscenity filter rewrote my statement as this: "Gravity is a pregnant dog." - LOL) |
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Post by john66 on Jan 17, 2011 17:18:48 GMT 1
I have two cubs, one which I am learning to fly on, and another complete one bought as spare parts, I intend to trial all mods on the orig Cub and then put together my new parts as a second cub for when my flying has improved.
John
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Post by renard80 on Jan 17, 2011 23:21:49 GMT 1
Congratulations on an imaginative concept, starboy. That is really nice work which I am sure will inspire many others.
I often wish I, too, had been born clever, rather than incredibly handsome.
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Post by john66 on Jan 18, 2011 0:19:33 GMT 1
I often wish I, too, had been born clever, rather than incredibly handsome. Believe me you don't, I unfortunately am burdened with both! John |
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Post by ginginho on Jan 18, 2011 12:46:12 GMT 1
I often wish I, too, had been born clever, rather than incredibly handsome. Believe me you don't, I unfortunately am burdened with both! John Having met you I'm struggling to believe this statement.  ;D Nice mod Starboy. |
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Post by john66 on Jan 18, 2011 12:54:37 GMT 1
Believe me you don't, I unfortunately am burdened with both! John Having met you I'm struggling to believe this statement. Just not your type maybe! John |
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Post by starboy on Jan 19, 2011 3:08:16 GMT 1
I often wish I, too, had been born clever, rather than incredibly handsome. Believe me you don't, I unfortunately am burdened with both! John I feel fortunate to be burdened with neither. I was simply born too darned lazy to put up with doing things the hard way and too darned ugly for people to want to do things for me. So if I have to do a thing myself I find a way to make it as easy on myself as possible. |
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;D