stunthanger.com
Electric Stunt => Gettin all AMP'ed up! => Topic started by: Motorman on January 20, 2016, 08:48:50 PM
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I've got a bunch of 4 cell batteries that are different shapes so I want a system where I can use them all in the same plane. What kind of Velcro straps are good for holding down the battery and where do you get them?
Thanks,
MM
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Do what you wish,, but I would reccomend staying away from velcro,, see my thread on my impact and my nats experience,,
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Ouch! guess I better come up with a better solution for different shape batteries.
MM
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perhaps a solid attachment to fit the largest battery,, and then spacers to adjust,, I am also mildly concerned about how different batteries will alter yoru CG
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I use different batteries for that very reasons. Balance the plane. :D
And I also am not a fan of velcro for holding batteries in place. For a number of reasons.
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I prefer to use the velcro not to let the battery completely loose.
With this way I never had problems.
Rogerio Fiorotti
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One of the guys at the RC club here has a balsa 3d plane with a removable battery tray. The battery is strapped into the plywood carrier, then slotted into the plane very easily.
Yes, Velcro is still used, but a backup strap can be used as well on top of the Velcro. Velcro has some distinct advantages in positioning and little to no slip between the hook and the loop.
I am not finding good pictures of "quick change" or "pull out" battery trays, but I might be using the wrong search terms.
Phil
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My Profile scale B-29 has the batteries in a slot on the nacelles with a Velcro strap to hold them in. The batteries face inboard toward the fuselage that means the centripetal force during flight is pulling the battery away from the nacelle on two of the nacelles. The velco strap goes under the plywood floor and the straps hold in the battery. The plywood floor fits into a slot in the nacelle and is screwed in place so it is held firm. I have no problems with this system.
All of my models with electric power use the Velcro straps with no problems. Now I am not doing any aerobatics so this may not be a fair comparison. I did spot this system that holds the battery with a wooden plate in a full body stunter at the 2014 Broken Arrow contest here in St Louis.
Fred
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B-29 nacelle with battery removed
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b-29 with battery installed
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I get the double sided Velcro from Lowes or Home Depot, one side is fuzzy and the other side has the hooks. Cut to length and run a Velcro strap under the battery floor and wrap it around the battery in two spots. I also make sure the battery can't move forward or aft and escape the Velcro straps
Fred
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I think that there's Velcro and then there's Velcro. I don't have a lot of confidence in Velcro if there's not a buckle to pull the Velcro through to cinch everything up tight before sticking it to itself. I like the Velcro straps used on RC helicopters like this http://www.progressiverc.com/spyder-strap.html
You put the battery in, slip the end of the Velcro through the buckle, pull it up really tight then stick it to itself. Of course, you want the Velcro strap to be well anchored first.
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I've used velcro "seat belts" for 6 years now on my profile and never had a problem.
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Crist, those are exactly the kind of straps I'm talking about.
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Crist, those are exactly the kind of straps I'm talking about.
Yup, they work great!
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I guess I'll pile on too. I've been using Velcro since day one, five years and many flights. I had one battery come out of my profile. That was my fault. I only had one strap and not enough contact on the battery to the fuselage.
Two years ago my full boogie PA airplane folded the wing coming out of the inverted wingover (more to that story). The airplane exploded and the motor, ESC, timer and battery still attached to the piece of plywood with Velcro was retrieved about 30 yards downstream. All of the components were used in the replacement project.
I have Velcro on the battery and the plywood to which it is attached. Then there are two straps around the battery laced through the plywood. Kinda like belts and suspenders.
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well,,
apparantly there are successful ways,, I know I had a couple guys show me the way they do it, HOwever for me, after watching my 14 ounce battery bounce through the pits at the Nats, whether it was because of me doing something wrong, or an inherant failure of the material, I dont want to leave that option on the table so I will use something more positive,,
more power to you Mike and others. as long as you have it working for you thats fine,, but as for me,, well,, yeah :D
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I don't blame you Mark, a constricted sphincter at someplace like L pad is not fun. If I had that experience there would be changes in my set up too.
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Not talking about profiles. On a profile all the velcro does is hold the battery in the pocket. The pocket takes up the G force. I hold the battery on my profile with rubber bands.
MM
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Not talking about profiles. On a profile all the velcro does is hold the battery in the pocket. The pocket takes up the G force. I hold the battery on my profile with rubber bands.
MM
So... build a pocket for your full fuselage? Rubber bands only makes you much braver than me.
Phil
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<snip On a profile all the velcro does is hold the battery in the pocket. The pocket takes up the G force. snip>
MM
Not true on all profiles.
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I never trusted velcro, that's why I'm using a hard attachment.
First, the battery box is made (balsa+glass), together with F1 and F2 (ply):
(http://www.modelbouwforum.nl/media/img_5333.224623/full?d=1453770418)
(http://www.modelbouwforum.nl/media/img_5334.224622/full?d=1453770365)
This is epoxied between the fuse sides (upside down on the board). Now it's a double walled box, giving the nose structure extra torsional rigidity:
(http://www.modelbouwforum.nl/media/img_5337.224624/full?d=1453770547)
Note the tiny bracket (brass, tapped M3 hole) it function will be explained later...
On the level of the box floor, F2 gets a 2 x 25 mm aperture.
This will receive the protruding end of the battery mounting plate (2mm ply)
(http://www.modelbouwforum.nl/media/accu01.224620/full?d=1453769760)
The battery slides in the box, until the end of the plate locks in F2,
then a tiny M3 bolt is screwed at the other end, locking the plate in place.
The battery is taped with glas reinforced tape to the mounting plate.
It's going nowhere, except with the model.
(http://www.modelbouwforum.nl/media/accu02.224621/full?d=1453769972)
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Anyone that wants to use Velcro, rock on. I have used it and I have had it fail. Didn't come out of the plane, but screwed some stuff up. I'm with Mark Scarborough, I'll go with positive mounts.
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I've seen two batteries ejected from electric powered models. In each case the batteries were being held in place with Velcro. I've never seen a battery that was held in place with bolts be ejected. Same holds true for hatches, I've seen hatches that were held in place with magnets come off. I've never seen a hatch that is held in place with bolts come off. Common sense to me is to use bolts!
Note that in the attached photo of the second electric re-fit of my Genesis Extreme model that I used a front mounted motor, but also used a rear bearing support. I later removed the rear support and had no problems with the bearings. This sort of relates to another thread on this forum about rear versus front mounting. In any case, the photo shows a battery that is being held in place with a 14-20 nylon bolt and nut. At the rear the battery holder has a tab that fits into a slot in a plywood former aft of the battery. Bulletproof mounting.
Later - Bob Hunt
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Bob, That looks different from other pics I've seen of your plywood ring system. The hold down in the front is different. Is this the evolution or is the maple cross piece with two 4-40's still good to use?
Thanks,
MM