REFLECTOR: Thunderstorms and composite airplanes

Scott Derrick scott at tnstaafl.net
Sun Aug 8 08:19:00 CDT 2004


The B52's story sounds true.  Hail is an entirely different phenomenon and 
can be ejected out of the top of a CB, thus using the high upper level 
winds at 40,45, 50,000 ft.  That's why its recommended you pass up wind to 
a large CB, if possible.

However taking a lightning strike at 15 miles!  I don't know.... Possible, 
anything's possible I guess.

Scott

At 11:34 PM 8/7/2004, KeithHallsten wrote:
>Scott,
>Maybe Paul was closer than estimated and maybe not.  Here is a follow-up
>post to Paul's:
>
>--> AeroElectric-List message posted by: "David Carter"
><dcarter at datarecall.net>
>A B-52 crew  faced a court martial in SAC for taking hail damage from a
>thunderstorm - they were in the clear about 20 miles away.  The facts of the
>case supported that they had acted prudently and had conscienciously  stayed
>a prudent distance away from the CB - they beat the rap.
>     -  Them buggers reach WAY OUT to getcha.
>David Carter
>
>
>----- Original Message -----
>From: "Scott Derrick" <scott at tnstaafl.net>
>To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>Sent: Saturday, August 07, 2004 2:40 PM
>Subject: Re: REFLECTOR: Thunderstorms and composite airplanes
>
>
> > Well,  I question the veracity of the authors estimate in distance to the
> > source.  If he was really 15 miles from the clouds I'm sure he would have
> > enough visibility to se if it was a CB or not.   It was more likely 5
> > miles.   He is a lucky man.  It almost sounds like he wanted to blame FSS
> > for telling him it was forcasted VFR and dang if during the flight there
> > wern't clouds in the sky!
> >
> > There is a great article about a strike in a
> > LongEZ   http://www.ez.org/cp53-p10.htm  This guy was in the soup though.
> >
> > If I could only fly my Velocity when it was severe clear, I think I'd just
> > sell it instead.
> >
> > Scott
> >
> > At 12:36 PM 8/7/2004, you wrote:
> > >Below is a recent post to the AeroElectric List that seems applicable to
> > >Velocity pilots as well.
> > >Keith
> > >
> > >
> > >Date:  8/04/2004
> > >Time: 04:51:52 PM PST US
> > >From: "Paul McAllister" <paul.mcallister at qia.net>
> > >Subject: AeroElectric-List: Lighting strike
> > >
> > >--> AeroElectric-List message posted by: "Paul McAllister"
> > ><paul.mcallister at qia.net>
> > >
> > >Hi all,
> > >
> > >At the prompting of Eric Jones I thought I would share my experience
> > >yesterday
> > >of a lighting strike.  I published a similar note on the Europa forum.
>For
> > >those
> > >unfamiliar it is composite construction.
> > >
> > >I departed yesterday from KUES up to Canada.  About 90 minutes into the
>trip
> > >I
> > >took a lightning hit.  The weather was forecasted VFR clear, however
>about
> > >70
> > >minutes into the trip I began to suspect all was "not as advertised".  I
> > >noticed
> > >a cloud about 15 miles of my port side this looked ominous so I diverted
> > >away
> > >from it.  I was about to call flight service when suddenly I saw a bright
> > >flash
> > >on the tip off my starboard wing.  The starboard side was clear blue sky
> > >and the port side was at least 10~15 miles from any clouds.  No obvious
>CB's
> > >were
> > >visible, however at 9000' it can be difficult to tell.
> > >
> > >The main contactor dropped off line so things went pretty quiet until I
> > >kicked
> > >in the "E Buss" circuit. (Thanks Bob!!)
> > >
> > >Damage is as follows:
> > >- The paint is blistered on the starboard wing tip and the port side is
>only
> > >blackened.
> > >- The wing tip lights (Eric's design) are destroyed with some of the
>screws
> > >melted.
> > >- My Narco 122 VOR/LOC/GS is destroyed
> > >- Wing leveler is destroyed
> > >- Electronic fuel gauge.  This is a microprocessor based device.
> > >- Main battery contactor (Kilovac EV200 AAANA) , which has an electronic
> > >power
> > >conservation circuit.
> > >- Manifold pressure sensing input to the EIS engine monitor.
> > >
> > >The Apollo GX 60 GPS/NAV/Com and transponder survived along with the EIS
>and
> > >electronic propeller controller. Internal inspection of the wing tips
> > >revealed no
> > >sign of burning and nothing was evident when I removed the instrument
>panel,
> > >or rear bulk heads. There appears to be no structural damage to the
>aircraft
> > >or welding of the control elements.  It appeared that  the lighting
>entered
> > >the
> > >starboard wing tip, traveled along the common ground between the LED wing
> > >tip
> > >lights and exited the port wing tip.
> > >
> > >Lessons learned?  Well it's hard to say.  I called for a standard
>briefing
> > >90 minutes
> > >before take off and was told "clear VFR, a nice afternoon to go flying".
> > >I called Flight Service an hour after the event and they told me that the
> > >convective
> > >activity that subsequently moved through was completely unexpected.
> > >I normally always file IFR, I think if I had done so this time I might
>have
> > >been
> > >warned.  I also think that I should have acted sooner on my hunch, a call
>10
> > >minutes sooner might have saved me a whole bunch of grief. Given that the
> > >conduction
> > >path was via the wing tip light ground I would probably increase the
> > >wire size to 14 gauge and do something similar for the conductive path
>down
> > >the
> > >back of the aircraft.  Bottom line, stay a long, long way from black
>looking
> > >clouds;
> > >20 miles isn't enough in a tempting target like a composite aircraft.
> > >
> > >Paul
> > >
> > >
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> >
> > "Those who sacrifice freedom to get security, deserve neither."
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> >
> >
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>
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"Those who sacrifice freedom to get security, deserve neither."
- Benjamin Franklin




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