I also believe that generally composites are considered more varaible than
materials like steel and aluminium etc.. Statistically speaking there will
be greater variation in the possible ultimate strengths of materials ( that
is the standard deviation is greater ). The greater material safety factors
used therefor only reflect the inherant variations of the material.
IMHO it would be unwise to compare tested strength of composite aircraft
against tested strength of metal aircraft.
The g limits recomended by the manufacturers are in all probability the ones
which should be observed at all times. That doesn't mean that that you wont
hear someone saying they exceeded the limits but they may have just been
lucky to have an aircraft which lies in the upper limts of the statistical
variation and not in the lower limits.
Jerry
lts@avnet.co.uk
http://www.avnet.co.uk/touchdown
----- Original Message -----
From: Graham Singleton <grasingleton@avnet.co.uk>
Subject: Re: Europa Questions Again
>
> >Now the Europa Aircraft website lists the limit load
> >rating as:
> >
> > Europa XS +3.8G -1.9G
> >
> >This would then place it in the "Normal" category and not
> >even allow steep turns. Am I missing something?
>
> The problem is the regulations. Because it is a composite airplane load
> factors are more than doubled over that required for a tin and rivets job.
> The Europa wing and center fuselage has demonstrated 8.5 G I understand,
> Andy please correct me.
> The reason for the conservative figures is the possibility of a real hot
> day. Composites lose strength quicker than metal at elevated temperatures.
> 65 degrees C and above would be hot.
> It is also worth noting that extreme cold makes some plastics brittle.
> Gliders have been damaged after cold soak at extreme altitude.
>
> Graham
>
>
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