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#21
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LiFePo Refit Part 23 AC
Hi Eric,
The advice I got from Fidel was specific to batteries mounted high in the vertical fin.Â* Think of an inverted pendulum.Â* The visible damage appears as long cracks in the gel coat partially around the tail boom at the leading edge of the base of the fin.Â* I wouldn't be surprised that there would be damage to the underlying structure, but I have no direct knowledge of that.Â* I doubt there's any mechanical problem with fuselage mounted batteries, though I always removed mine so that they'd be fully charged when I arrived at my destination.Â* They were ease to remove, however. Dan On 3/12/2020 8:43 AM, Eric Greenwell wrote: wrote on 3/12/2020 1:35 AM: I'll second the recommendation on batteries OUT for trailering.Â* Especially tail fin installs. Is that based on gel coat cracking (the original reason for removing the tail battery), the potential for fires caused by the battery while trailering, or to protect the battery from damage during trailering? Removing the main batteries from a Schleicher motorglider (ASH 26E and later), and DG motorgliders is very time-consuming. Since I'm not aware of any problems caused by leaving the main batteries in during trailering in these gliders, I think removing and replacing them is likely to cause more problems than it avoids. -- Dan, 5J |
#22
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LiFePo Refit Part 23 AC
That's why when I replaced the SLA tail battery in my Experimental
LAK-17a with a LiFePO4, I placed the new battery behind the seat back.Â* I replaced the weight removed from the tail with an ingot of lead of the same weight as the battery that was removed.Â* The lead ingot was sealed in the LAK removable battery box that was designed to fit that location. On 3/12/2020 9:10 AM, Jonathon May wrote: If you are changing from, SLA to lipo the distance from the Cof G is important . Just changing the nose battery in a ventus to lipo could make for a very interesting day. At 14:43 12 March 2020, Eric Greenwell wrote: wrote on 3/12/2020 1:35 AM: I'll second the recommendation on batteries OUT for trailering. Especially tail fin installs. Is that based on gel coat cracking (the original reason for removing the tail battery), the potential for fires caused by the battery while trailering, or to protect the battery from damage during trailering? Removing the main batteries from a Schleicher motorglider (ASH 26E and later), and DG motorgliders is very time-consuming. Since I'm not aware of any problems caused by leaving the main batteries in during trailering in these gliders, I think removing and replacing them is likely to cause more problems than it avoids. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 -- Dan, 5J |
#23
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LiFePo Refit Part 23 AC
The horizontal stabilizer on a glider weighs far more than any of the tail
batteries I've encountered, and when flying the glider, especially the takeoff and landing, that heavy horizontal puts a lot more forces (vertically and twisting) on the tail boom than the battery. In a trailer, the forces are almost entirely vertical, and are also far less than the landing/takeoff pounding the tail gets. So I'm skeptical the gel coat cracking is due to the battery during trailering. How did Fidel determine it was the battery/trailering, and not the normal operation of the glider, or some other cause? Dan Marotta wrote on 3/12/2020 10:06 AM: Hi Eric, The advice I got from Fidel was specific to batteries mounted high in the vertical fin.* Think of an inverted pendulum.* The visible damage appears as long cracks in the gel coat partially around the tail boom at the leading edge of the base of the fin.* I wouldn't be surprised that there would be damage to the underlying structure, but I have no direct knowledge of that.* I doubt there's any mechanical problem with fuselage mounted batteries, though I always removed mine so that they'd be fully charged when I arrived at my destination.* They were ease to remove, however. Dan On 3/12/2020 8:43 AM, Eric Greenwell wrote: wrote on 3/12/2020 1:35 AM: I'll second the recommendation on batteries OUT for trailering. Especially tail fin installs. Is that based on gel coat cracking (the original reason for removing the tail battery), the potential for fires caused by the battery while trailering, or to protect the battery from damage during trailering? Removing the main batteries from a Schleicher motorglider (ASH 26E and later), and DG motorgliders is very time-consuming. Since I'm not aware of any problems caused by leaving the main batteries in during trailering in these gliders, I think removing and replacing them is likely to cause more problems than it avoids. -- Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me) - "A Guide to Self-Launching Sailplane Operation" https://sites.google.com/site/motorg...ad-the-guide-1 |
#24
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LiFePo Refit Part 23 AC
It's just a simple thing you can do to remove one risk factor.Â* Take it
for what it's worth and do what you like. On 3/12/2020 12:09 PM, Eric Greenwell wrote: The horizontal stabilizer on a glider weighs far more than any of the tail batteries I've encountered, and when flying the glider, especially the takeoff and landing, that heavy horizontal puts a lot more forces (vertically and twisting) on the tail boom than the battery. In a trailer, the forces are almost entirely vertical, and are also far less than the landing/takeoff pounding the tail gets. So I'm skeptical the gel coat cracking is due to the battery during trailering. How did Fidel determine it was the battery/trailering, and not the normal operation of the glider, or some other cause? Dan Marotta wrote on 3/12/2020 10:06 AM: Hi Eric, The advice I got from Fidel was specific to batteries mounted high in the vertical fin.Â* Think of an inverted pendulum.Â* The visible damage appears as long cracks in the gel coat partially around the tail boom at the leading edge of the base of the fin.Â* I wouldn't be surprised that there would be damage to the underlying structure, but I have no direct knowledge of that.Â* I doubt there's any mechanical problem with fuselage mounted batteries, though I always removed mine so that they'd be fully charged when I arrived at my destination.Â* They were ease to remove, however. Dan On 3/12/2020 8:43 AM, Eric Greenwell wrote: wrote on 3/12/2020 1:35 AM: I'll second the recommendation on batteries OUT for trailering. Especially tail fin installs. Is that based on gel coat cracking (the original reason for removing the tail battery), the potential for fires caused by the battery while trailering, or to protect the battery from damage during trailering? Removing the main batteries from a Schleicher motorglider (ASH 26E and later), and DG motorgliders is very time-consuming. Since I'm not aware of any problems caused by leaving the main batteries in during trailering in these gliders, I think removing and replacing them is likely to cause more problems than it avoids. -- Dan, 5J |
#25
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LiFePo Refit Part 23 AC
The loads and vibration imparted while trailering far exceed flight loads. Bob Carlton has trailered his airshow Salto around the country for years, and I can attest that a simple ten mile trip on the road will peg the G-Meter at +10 and -10 Gs. Side loads are probably not as severe, but we have no method of measuring those loads, simply because the Salto has a "V" tail, and the tail airfoils are removed for transport.
One thing I installed in my 1983 Cobra trailer is a thick foam pad at the top of the rudder box. When the trailer top is pulled down into the closed position, the foam compresses against the top of the rudder, damping side-to-side motion and vibration. Still, it's a good idea to remove the top mounted tail battery. Gelcoat repairs aren't cheap, but fiberglass work is really expensive. Ask me how I know this. |
#27
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LiFePo Refit Part 23 AC
Mark, if you're really interested you could rotate the G-meter 90
degrees in either direction. :-D On 3/12/2020 7:26 PM, wrote: The loads and vibration imparted while trailering far exceed flight loads. Bob Carlton has trailered his airshow Salto around the country for years, and I can attest that a simple ten mile trip on the road will peg the G-Meter at +10 and -10 Gs. Side loads are probably not as severe, but we have no method of measuring those loads, simply because the Salto has a "V" tail, and the tail airfoils are removed for transport. One thing I installed in my 1983 Cobra trailer is a thick foam pad at the top of the rudder box. When the trailer top is pulled down into the closed position, the foam compresses against the top of the rudder, damping side-to-side motion and vibration. Still, it's a good idea to remove the top mounted tail battery. Gelcoat repairs aren't cheap, but fiberglass work is really expensive. Ask me how I know this. -- Dan, 5J |
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