On board battery(ies) for powering radios/Flarm etc

[Neal Alders]

Just a quick question.
Had a brainstorm the other day, might have hit my head, don't remember, who knows...

What are y'all using for on board power these days?

Last I flew, we were using 6? amp hour gel cells by Hobbico from Tower Hobbies. (The kind that powered the little Powerwheels Jeep your kid/grandkid rode in 20 years ago)

What kind of power capacity are folks using?

I was working my big a$$ Milwaukee 10" chop saw and saw how compact the 18v, 9 amp LiPo was, and how fast it charged on the included rapid charger and got to thinking 1, 2 or 3 of those on a semi-custom mount with built in voltage regulator would be right dandy in these birds, and available at the big orange box store if a replacement is needed in a hurry.

Just a thought. Please return to your regularly scheduled mayhem.

[Michael Bamberg]

Neal,

I think there are still a lot of pilot using Sealed Lead Acid (SLA) batteries in their glider. It works OK for gliders that maybe have an electronic Vario and a radio.

As you add other electric devices, especially a transponder, the capacity demands go up. You can get SLA batteries with 12-15AH capacity, but many ships are equipped with Lithium/Iron/Phosphate (LiFePo) chemistry batteries.

Most of the sailplane accessory distributors have them in stock, for example:

http://craggyaero.com/lifepo4_battery1.htm

Hope that helps,

Mike

[Tango Eight]

On Monday, October 12, 2020 at 10:10:18 PM UTC-4, wrote:

> What kind of power capacity are folks using?

Most popular are lithium iron phosphate (LFP) batteries in same form factor as those old 6AH SLAs, now typically with 9 - 10 AH capacity. Decent quality examples last for years and years with little change in capacity... and your radio still transmits
from the wave at -20C at 10% state of charge (however, do not recharge until battery warms up).

Modern (Chinese) SLAs are of poor quality, not nearly as good as what we had (at higher cost) from Western manufacturers in 1990s.

(btw, try the search function, works great, will return hours of reading on this very topic)

T8

[[email protected]]

Yes, I also looked longingly at the tool batteries as well. A 3d printer could make a holder/connector and there are plenty of demo boards around for switching powersupplies to make 12V.

But I decided to go with three K2's. So far I've never used the third K2.

They were already tested and in the physical and electrical form the glider expects.
LiFePo seemed more forgiving than LiIon.
I'd rather not divert the hobby from flying to building battery systems.
It seemed a thing that would be fun and easy to get close, but tricky to get right.

If the K2's didn't work so well, it might be a different story.

[[email protected]]

On Tuesday, October 13, 2020 at 9:35:47 AM UTC-4, wrote:
> Yes, I also looked longingly at the tool batteries as well. A 3d printer could make a holder/connector and there are plenty of demo boards around for switching powersupplies to make 12V.
>
> But I decided to go with three K2's. So far I've never used the third K2..
>
> They were already tested and in the physical and electrical form the glider expects.
> LiFePo seemed more forgiving than LiIon.
> I'd rather not divert the hobby from flying to building battery systems.
> It seemed a thing that would be fun and easy to get close, but tricky to get right.
>
> If the K2's didn't work so well, it might be a different story.

And tricky to keep a home-made kludge safe. Other types of lithium batteries are prone to spontaneous combustion. You don't want a fire in flight! A ready-made LFP battery, with a built-in circuit protecting it from over-current etc, in a proper case that fits in your glider, can now be bought for around $40 - hardly more expensive than an old-tech SLA. It's a no-brainer.

[Richard Pfiffner[_2_]]

On Monday, October 12, 2020 at 7:26:11 PM UTC-7, Michael Bamberg wrote:
> Neal,
>
> I think there are still a lot of pilot using Sealed Lead Acid (SLA) batteries in their glider. It works OK for gliders that maybe have an electronic Vario and a radio.
>
> As you add other electric devices, especially a transponder, the capacity demands go up. You can get SLA batteries with 12-15AH capacity, but many ships are equipped with Lithium/Iron/Phosphate (LiFePo) chemistry batteries.
>
> Most of the sailplane accessory distributors have them in stock, for example:
>
> http://craggyaero.com/lifepo4_battery1.htm
>
> Hope that helps,
>
> Mike

Test Graph is include with every LIFEPO4 Battery sold by Craggy Aero.

Richard
www.craggyaero.com

[jfitch]

Also keep in mind that AFAIK power tool batteries (certainly the Milwaukee) have no intelligence - all the BMS functions are built into the charger and tools. So you have a volatile, uncontrolled LiPo sitting behind your head.. You can get the same AH in a well constructed, controlled LiFePo4 for the same or less money.
On Tuesday, October 13, 2020 at 7:21:25 AM UTC-7, wrote:
> On Tuesday, October 13, 2020 at 9:35:47 AM UTC-4, wrote:
> > Yes, I also looked longingly at the tool batteries as well. A 3d printer could make a holder/connector and there are plenty of demo boards around for switching powersupplies to make 12V.
> >
> > But I decided to go with three K2's. So far I've never used the third K2.
> >
> > They were already tested and in the physical and electrical form the glider expects.
> > LiFePo seemed more forgiving than LiIon.
> > I'd rather not divert the hobby from flying to building battery systems..
> > It seemed a thing that would be fun and easy to get close, but tricky to get right.
> >
> > If the K2's didn't work so well, it might be a different story.
> And tricky to keep a home-made kludge safe. Other types of lithium batteries are prone to spontaneous combustion. You don't want a fire in flight! A ready-made LFP battery, with a built-in circuit protecting it from over-current etc, in a proper case that fits in your glider, can now be bought for around $40 - hardly more expensive than an old-tech SLA. It's a no-brainer..

[George Haeh]

CTEK makes a dedicated LiFePO4 charger. Not cheap, but I get some six hours running radio, PowerFLARM, vario, Oudie and transponder on a K2.

[Neal Alders]

My current gen 18v Milwaukee batteries all have on board intelligence and can signal when an issue occurs through flashing lights etc. They are highly protected against fire, shorts etc. The smaller 12v versions do not that I am aware of. The newer M28 batteries, 28 volts with capacities exceeding 40amp hours are coming around the corner. They will be integrated into generators, compressors etc. Exciting new battery tech out there.

This older platform on google groups is not very search friendly, and I was unable to locate much of anything, so I tossed the question out there.

[Papa3[_2_]]

On Monday, October 12, 2020 at 10:10:18 PM UTC-4, wrote:
> Just a quick question.
> Had a brainstorm the other day, might have hit my head, don't remember, who knows...
>
> What are y'all using for on board power these days?
>
> Last I flew, we were using 6? amp hour gel cells by Hobbico from Tower Hobbies. (The kind that powered the little Powerwheels Jeep your kid/grandkid rode in 20 years ago)
>
> What kind of power capacity are folks using?
>
> I was working my big a$$ Milwaukee 10" chop saw and saw how compact the 18v, 9 amp LiPo was, and how fast it charged on the included rapid charger and got to thinking 1, 2 or 3 of those on a semi-custom mount with built in voltage regulator would be right dandy in these birds, and available at the big orange box store if a replacement is needed in a hurry.
> FSC
> Just a thought. Please return to your regularly scheduled mayhem.


Like others I'm using two LiFePo4 batteries (10ah K2s). I've measured my current draw (Clearnav, Clearnav vario, Trig T21, Dittel FSG 2T) and it averages 1.26A in flight on a fresh charge. Other than a 1000K flight that lasted 9 hours, I've never had to switch batteries. After 3 years, the currently older K2 still measures about 9.2ah of capacity at full charge.

P3

[Neal Alders]

Thanks for that link. Price is decent, under a $100 for a 10 amp hour battery. I think I could easily over double that capacity with a couple power tool batteries in the same cubic space, however, the cost would be 4 times that.

LiPo tech has come a Looooooong way in the last 5 years. I cannot recall hearing about a LiPo combusting during use in a long time. Even at the ultra high amp draws I use in my chop saw, the batteries dont even get warm.

I was always anti-battery power tool until my first Milwaukee impact driver/hammer drill set 2 years ago. I have spent the last year renovating my house and upgrading all my tools. I am nearly 100% cordless now. I just had a wild idea that perhaps some of this new battery tech can come the way of soaring. I wasn't sure if anyone else was out there doing it.

[Eric Greenwell[_4_]]

Neal Alders wrote on 10/13/2020 10:56 AM:
> Thanks for that link. Price is decent, under a $100 for a 10 amp hour battery. I think I could easily over double that capacity with a couple power tool batteries in the same cubic space, however, the cost would be 4 times that.
>
> LiPo tech has come a Looooooong way in the last 5 years. I cannot recall hearing about a LiPo combusting during use in a long time. Even at the ultra high amp draws I use in my chop saw, the batteries dont even get warm.
>
> I was always anti-battery power tool until my first Milwaukee impact driver/hammer drill set 2 years ago. I have spent the last year renovating my house and upgrading all my tools. I am nearly 100% cordless now. I just had a wild idea that perhaps some of this new battery tech can come the way of soaring. I wasn't sure if anyone else was out there doing it.
>
Instrument power is easily and cheaply solved with several brands of LiFe 12 volt batteries.
What we'd really like to see is better batteries for electric sailplanes (aka "traction
batteries"), specially more energy/mass and lower cost. Smaller would be useful, too, but not
nearly so much.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Neal Alders]

Im waiting for Super Capacitors to get perfected. I think LiPo and brushless batteries have made significant strides, and Super Capacitors would further that another generation of capability in electric powered aircraft.

Speaking of which,

Anyone know anything about this side by side self launch 15 meter bird, the Pipstrel Taurus? Electric or gas power?

[Eric Greenwell[_4_]]

Neal Alders wrote on 10/14/2020 9:05 AM:
> Im waiting for Super Capacitors to get perfected. I think LiPo and brushless batteries have made significant strides, and Super Capacitors would further that another generation of capability in electric powered aircraft.
>
> Speaking of which,
>
> Anyone know anything about this side by side self launch 15 meter bird, the Pipstrel Taurus? Electric or gas power?
>
Look at the Pipstrel website for details and dealer info; also, there is at least one of each
(gas/electric) in the US.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Neal Alders]

I have explored the website, was just looking to see if anyone had any experience or an opinion on them is all.

[Eric Greenwell[_4_]]

Neal Alders wrote on 10/14/2020 9:31 AM:
> I have explored the website, was just looking to see if anyone had any experience or an opinion on them is all.
>
I suggest using the FAA registration data base for owners, and contacting them. There was also
an article or two in Soaring Magazine in the last 2-3 years - good starting places. The people
with these gliders in the US generally aren't on RAS, so you need to find them. Or call the
dealer and talk to him - he might be willing to give you owner contact info.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

[Dave Walsh[_2_]]

At 16:31 14 October 2020, Neal Alders wrote:
>I have explored the website, was just looking to see if anyone had any
>experience or an opinion on them is all.
>
I've flown with several in typical Alpine conditions but I haven't flown
one. Several petrol (gas) versions operate at Sisteron, French Alps, and
seem to be universally well liked by their pilots. The good features are:
-
Simple to taxi due to twin wheel U/C & steerable tail wheel
Good climb rate
Spacious cockpit
Good in flight visibility
Reliable Rotax two-stroke engine
In Europe it's an ultralight so (currently) outside EASA admin
Build quality very good
Light & simple to rig/de-rig
Good support from the makers
If you a coming from a conventional glider you will notice the Va and Vne
are low. They seem to climb well, especially when you remember you
have a two seat self-launch glider with a 15m wing span. Glide
performance is adequate but reportedly you need to keep the speed
down. If you are coming from a modern 15/18m ship you will likely feel
the performance limits.

[John DeRosa OHM Ω http://aviation.derosaweb.net]

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

[Neal Alders]

Makes a lot of sense. And coming back to soaring after a 20 year hiatus, and getting some positive feedback is a pleasant change.

Thanks for that John. I understand the standardization aspect. I am coming out of Schweitzer Iron from back in the day, best ship I have flown was the 1-35. Nothing standard in those birds battery location and mounting.

Hence why I asked. I wasn't sure if the new manufactured sailplanes are still running the old stuff. I thought for sure some upgrades in battery capacity and capability would have occurred in the last 2 decades with the increase load demands of the modern cockpit avionics.


As for the Pipstrel, thanks for that feedback Dave. I appreciate the quick rundown, that's exactly the kind of intel I was looking for. I have a fellow captain at my airline who recently joined the club I belong to, and is expressing the same interest in a self launcher as I, so we are not tied down to any club to soar. We are not competitors, and not record chasers. We just want to go soaring. The reception and attitudes towards new, adult soaring enthusiasts, especially professional pilots, while generally good at the club we belong to, has honestly not been too good at others he and I have both visited over the last few years. I guess I am spoiled having been brought up at Valley Soaring under UH's tutelage.

[Dan Marotta]

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

[Dan Marotta]

I saw one in Moriarty a few years back.Â* As I recall it was a gas
powered version.Â* And, while I liked the look of it, it appeared to me
to be very lightly constructed.Â* Just my opinion.

On 10/14/2020 10:31 AM, Neal Alders wrote:
> I have explored the website, was just looking to see if anyone had any experience or an opinion on them is all.

--
Dan, 5J

[[email protected]]

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.

[kinsell]

On 10/14/20 10:31 AM, Neal Alders wrote:
> I have explored the website, was just looking to see if anyone had any experience or an opinion on them is all.
>

50 hp in a two place side by side with stubby wings, engine mfg out of
business. I would say it's significantly underpowered if trying to fly
out of higher elevation airports, anything over 4500 ft msl on a hot day
with two people.

[kinsell]

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.

[[email protected]]

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.

[kinsell]

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.

[Dan Daly[_2_]]

> >>> 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.

SZD-55 has a 2.2 kg SLA battery low in the fin, and a water tank just forward of it; works very well.

[andy l]

On Thursday, 15 October 2020 at 17:09:37 UTC+1, wrote:
> On Thursday, October 15, 2020 at 11:23:10 AM UTC-4, Dan Marotta wrote:
> > A question to the ether that, perhaps the manufacturers will see and
> > think is a good idea: 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?

> 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.

So does cutting a hole in the location given

It could be strengthened around the edges of the hole, of course, and that extra structure can go towards the extra weight needed