ASW 27 destroyed by lightning in trailer

On Thursday, September 26, 2019 at 8:31:11 PM UTC-7, Steve Leonard wrote:
On Thursday, September 26, 2019 at 8:27:06 PM UTC-5, 2G wrote:

The photo of the trailer showed a strike mark near the front of the trailer where the carpet ends. This indicated to me that it exited out of the bottom of the nose.

Tom

Hi Tom,
Looks to me like that picture is looking up into the fin box. I don't see any gray floor in that pic, but black like in the glass top of the trailer. There is red carpet visible in the elevator drive box, and burn marks on the white foam (owner added?) that might kinda line up with the top of the vertical being in there.

Just another opinion.
Steve Leonard

As a lightning guy who has inspected and analyzed many things struck by lightning (including aircraft, helicopters, gliders and vehicles), maybe I could add a few comments.

The lightning entry point was certainly the top of the trailer and into the metal control system for the elevator at the top of the fin. From the control system, it would have travelled to the bottom of the rudder and could either have exited straight down into the nearest metal of the trailer floor and/or forwards along the fuselage along the control rods and rudder cables. Exiting from metal, lightning typically leaves a nice characteristic melted area which would be easy to find if they were examined. How the lightning got out of the fuselage isn't obvious to me from the photos. If it went through fiberglass, the damage would be obvious.

Since the metal control systems of gliders are not electrically continuous, there is the possibility of arcing across gaps, which can develop significant pressure. The possibility of damage inside the the fin and fuselage from this cannot be known without inspection, but I would suspect it to be repairable. The wings are almost certainly unaffected.

Where the lightning exited the trailer to ground is also not known from the available photos. Many lightning-damaged vehicles I have examined have one or more flat tires, destroyed by lightning current. Tires are not very good insulators - they are black because they are full of carbon and may also have steel wire inserts. Flashover to ground from the axle or wheels is commonly seen in videos of vehicle lightning strikes. Just remember, lightning has traveled around 5 miles through air, which is a pretty darned good electrical insulator - a few inches from trailer to ground is nothing!

Mike

On Thursday, September 26, 2019 at 9:27:06 PM UTC-4, 2G wrote:
On Thursday, September 26, 2019 at 1:07:38 PM UTC-7, wrote:
On Wednesday, September 25, 2019 at 8:21:40 PM UTC-4, 2G wrote:
On Wednesday, September 25, 2019 at 12:13:26 PM UTC-7, wrote:
As I understand it, lightning is seeking the path of least resistance to the ground. It went through the fiberglass trailer top and entered the ship at the top of the fin, question would be; where did it exit? The ship is sitting on rubber wheels (tail wheel and dolly wheels), so did it exit at the tail wheel into the aluminum floor, then to the rear legs, if they were down? Or, did it run the full length of the fuselage and exit through the saddle aluminum arms, then jump the rubber tires then into the floor out to the tongue and into the chains. To the tie-down point? Also, did it fry that good looking instrument panel on its way to ground? I believe other lightning strikes followed the metal push-rods, which offer less resistance than carbon fiber structure.
Food for thought, before placing your bid + that Cobra trailer is worth something close to 10K.
Cheers,
JJ

It looks like the current went down the pushrods and exited somewhere near the nose and thru the trailer floor. Carbon fiber is conductive, but high resistance to the point that commercial composite aircraft must include conductors to handle lightning current (https://www.compositesworld.com/arti...site-aircraft). I guess that the fuselage is okay with the possible exception of welded pushrod junctions. The instruments condition is unknown, but could be inspected. The most vulnerable instruments are the radio and transponder, and current could have jumped from them to other instruments.

Tom

I could not get any sense of where the exit point was.
How did you? or is this an educated guess?
I agree path likely got to push rods.
UH

The photo of the trailer showed a strike mark near the front of the trailer where the carpet ends. This indicated to me that it exited out of the bottom of the nose.

Tom

The photo of red and gray with hole is the entry point at the top of the fin housing.
UH

On Thursday, September 26, 2019 at 9:28:17 PM UTC-4, 2G wrote:
On Thursday, September 26, 2019 at 1:09:18 PM UTC-7, Charlie M. (UH & 002 owner/pilot) wrote:
I believe I have a couple hundred hours in THAT ship (based on "N number"), sad to see it's demise.....:-(

I think the glider can be repaired, and the damage is not that great.

Tom

True.
The problem for someone taking on this project is complex.
1) Need replacement aft section to do it right.
2) Getting a reasonable price after repair and refinish will be problematic.
3) Return to service after the factory, taking a very conservative position, said cut it up. Liability exposure is huge.
Sigh- It was a great ship for me.
UH

Ain't it great when someone who knows what the HELL he's talking about,
weighs in?

Thanks, Mike.

On 9/26/2019 10:14 PM, Mike the Strike wrote:
On Thursday, September 26, 2019 at 8:31:11 PM UTC-7, Steve Leonard wrote:
On Thursday, September 26, 2019 at 8:27:06 PM UTC-5, 2G wrote:
The photo of the trailer showed a strike mark near the front of the trailer where the carpet ends. This indicated to me that it exited out of the bottom of the nose.

Tom
Hi Tom,
Looks to me like that picture is looking up into the fin box. I don't see any gray floor in that pic, but black like in the glass top of the trailer. There is red carpet visible in the elevator drive box, and burn marks on the white foam (owner added?) that might kinda line up with the top of the vertical being in there.

Just another opinion.
Steve Leonard
As a lightning guy who has inspected and analyzed many things struck by lightning (including aircraft, helicopters, gliders and vehicles), maybe I could add a few comments.

The lightning entry point was certainly the top of the trailer and into the metal control system for the elevator at the top of the fin. From the control system, it would have travelled to the bottom of the rudder and could either have exited straight down into the nearest metal of the trailer floor and/or forwards along the fuselage along the control rods and rudder cables. Exiting from metal, lightning typically leaves a nice characteristic melted area which would be easy to find if they were examined. How the lightning got out of the fuselage isn't obvious to me from the photos. If it went through fiberglass, the damage would be obvious.

Since the metal control systems of gliders are not electrically continuous, there is the possibility of arcing across gaps, which can develop significant pressure. The possibility of damage inside the the fin and fuselage from this cannot be known without inspection, but I would suspect it to be repairable. The wings are almost certainly unaffected.

Where the lightning exited the trailer to ground is also not known from the available photos. Many lightning-damaged vehicles I have examined have one or more flat tires, destroyed by lightning current. Tires are not very good insulators - they are black because they are full of carbon and may also have steel wire inserts. Flashover to ground from the axle or wheels is commonly seen in videos of vehicle lightning strikes. Just remember, lightning has traveled around 5 miles through air, which is a pretty darned good electrical insulator - a few inches from trailer to ground is nothing!

Mike

--
Dan, 5J

On Thursday, September 26, 2019 at 8:31:11 PM UTC-7, Steve Leonard wrote:
On Thursday, September 26, 2019 at 8:27:06 PM UTC-5, 2G wrote:

The photo of the trailer showed a strike mark near the front of the trailer where the carpet ends. This indicated to me that it exited out of the bottom of the nose.

Tom

Hi Tom,
Looks to me like that picture is looking up into the fin box. I don't see any gray floor in that pic, but black like in the glass top of the trailer. There is red carpet visible in the elevator drive box, and burn marks on the white foam (owner added?) that might kinda line up with the top of the vertical being in there.

Just another opinion.
Steve Leonard

Without better identification of where the photos were taken, we are just guessing. It seemed plausible to me that the exit point was on the trailer floor to the ground, but lightning does go many directions.

Tom

Mike the Strike wrote on 9/26/2019 9:14 PM:
As a lightning guy who has inspected and analyzed many things struck by lightning (including aircraft, helicopters, gliders and vehicles), maybe I could add a few comments.

Is "Mike the Strike" a reference to your expertise?

--
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

On Friday, September 27, 2019 at 12:34:01 PM UTC-4, Dan Marotta wrote:
Ain't it great when someone who knows what the HELL he's talking about,
weighs in?

Quite shocking.

Yes Eric it is, Im not sure but I think hes been hit a few times He is definetly our weather guru in AZ. Knows his ****, and we are teally happy when he shows up with a white hat on to the pilots meeting

CH

On Friday, September 27, 2019 at 10:25:58 PM UTC+1, Dave Nadler wrote:
On Friday, September 27, 2019 at 12:34:01 PM UTC-4, Dan Marotta wrote:
Ain't it great when someone who knows what the HELL he's talking about,
weighs in?

Quite shocking.

I saw what you did there Dave.

From the man who did inspection right after it happened. The fuselage was tilted in dolly. Horizontal stab pins were touching fin box. That is where lightening entered. There is no visible evidence of exit, anywhere. Suspected maybe went down the fin, jumped to trailer and forward out to ground through safety chain that was attached to tie down stake at front of trailer. Inside of fin was shattered and frayed only partially down from entry point..No visible damage to fuselage. Aircraft was totalled because of these unknowns.