On 10/15/20 12:31 PM, wrote:
On Thursday, October 15, 2020 at 1:23:28 PM UTC-4, kinsell wrote:
On 10/15/20 10:08 AM, wrote:
On Thursday, October 15, 2020 at 11:23:10 AM UTC-4, Dan Marotta wrote:
Good points John.

A question to the ether that, perhaps the manufacturers will see and
think is a good idea:Â* Why not mount the tail battery low on the tail
rather than at the top where it makes an inverted pendulum? Maybe a door
at the aft side of the tail boom above the tail wheel?

On 10/14/2020 12:49 PM, John DeRosa OHM Ω http://aviation.derosaweb.net
wrote:
Interesting ideas. Just a couple of comments (you knew this was coming)...

- It seems that most (many?) (new?) gliders have an existing space for one or more batteries in various locations. The common places seem to be behind the pilot near the spars in the cargo area and/or at the top of the vertical stabilizer.

- Each of these locations fits a specific size of battery for obvious standardizing reasons.

- One of the most common "standard" size batteries that I have found used in gliders are the brick sized 5.95"(150mm) x 2.56"(65mm) x 3.7"(95mm) with blade/faston type connections. These rechargeable batteries often have "1207", "1270" or "EB-12" in their model numbers.

- This size of SLA batteries have been around for many, many, years. As mentioned above we see them in kid's motorized toys. I found them in computer UPS systems, security alarm systems, and in those large car battery jump starters (with air pump, light, 12Vdc output, AC inverter, USB, kitchen sink).

- Because this size of battery is used to power such a wide diversity of systems they are very commonly available at hardware, auto parts and battery stores in nearly ever sized city, not to mention at Walmart and Amazon. I found this out a few years back after forgetting my (lithium) batteries and ran to the local NAPA to get replacement (SLA) batteries and fuse holders. I could have also borrowed from fellow glider pilots.

Bottom line: Moving to a battery system as found in battery powered tools is depending on something that is propriety in size and pin connections and is less likely to be found in a pinch let alone years from now. Sorry, I like easy to find and non-proprietary batteries.

As always, my $0.02.

- John DeRosa OHM Ω

--
Dan, 5J

Yeah I've always wondered about that. Any added mass at the top of the tail only increases the chance of damage in case of a groundloop.


Mike Adams, the old LS dealer specifically told me not to put a battery
in the tail of my LS-4 for that reason.

A buddy of mine flies an LS4 and puts a rather heavy conglomeration of gel-cells in the top of the tail. Alas he needs that for the weight and balance. That seems common? If not a battery, then a tank of water in the tail. Why don't glider manufacturers include a metal blob inside the tail boom that can be adjusted fore and aft to get your CG where you want it? I imagine something like a long screw with a hand crank. Would need some sort of indicator though, so you'll know what you dialed.


It's common to put batteries there although finding actual gell cells
would be almost impossible these days. I did go ahead and put a 14V 5
A-H sla battery there for w&b. Water tanks in the tail are generally
down low, if installed.