A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Troubling story and some questions



 
 
Thread Tools Display Modes
  #1  
Old January 1st 08, 05:20 PM posted to rec.aviation.soaring
Nyal Williams
external usenet poster
 
Posts: 215
Default Troubling story and some questions

I apologize in advance:

Do the rest of you think 'violin' is fiddling the numbers?
grin

HAPPY NEW YEAR

At 14:54 01 January 2008, wrote:
What does your POH say about opening spoilers at high
speed? Below
Maneuvering Speed (80 kts, I checked) it shouldn't
be a big deal.
FWIW, I think you did the right thing in losing speed
right now, rather
than thinking of the FAA implications. Could the
feds ground you from
flying your ultralight anyway (probably)? ;-)


Forgive me if this strays from the thread a little,
but I think it is
worth expanding on the relationships between maneuvering
speed (Va),
spoilers and speeds/loads. Here is my understanding:

1. There is no relationship between Va (maneuvering
speed) and
spoilers, except that Va is determined with spoilers
retracted. Va is
based on pitch (elevator inputs). There is a general
belief that
below Va you can do anything with any flight control,
and the glider
cannot be damaged. This is may be true in some, perhaps
many,
situations, but it is not true in any certification
sense. [See EASA
glider regs CS 22.335]

2. Once spoilers are deployed, the loads for which
the glider is
certified drop to +3.5 from +5.3 (utility) / +7.0 (aerobatic).
[See
EASA glider regs CS 22.345]

For the reason stated in #2 above, 'The Handbook of
Glider
Aerobatics' (Mallinson and Woollard, 1999, page 30)
states 'It is
nearly always better to slow a glider by 'pulling g'
rather than by
operating the airbrakes'. They are speaking here of
aerobatic gliders
(rated to 7 g's) during aerobatic maneuvers. There
is some difference
in the loads/slowing that can be achieved by utility
gliders. Also,
there are other considerations when using 'g' to slow
(symmetric
loads, etc.). For the purposes of this discussion,
I think I'm safe
with the summarization that the choice of spoiler over
'g' should not
be automatic in all situations.

This is not to say that spoilers may or may not have
been an
appropriate response in the case being discussed, or
many other
situations. Rather, I want to dissuade those who might
feel that
spoilers are an appropriate response in every situation.
Certainly
deploying spoilers and pulling high g's could be a
catastrophic
combination.

I am certainly open to correction if there is an error
in my analysis.

Regards,
Eric




 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
More Troubling Planetary News!!! Michael Baldwin, Bruce[_2_] Products 1 August 24th 07 07:10 AM
More Troubling Planetary News Michael Baldwin, Bruce Products 3 January 24th 07 03:40 AM
More Troubling Planetary News Michael Baldwin, Bruce Products 2 November 20th 06 03:15 AM
More Troubling Planetary News Michael Baldwin, Bruce Products 10 November 17th 06 02:57 AM
Erosion of U.S. Industrial Base Is Troubling The Enlightenment Military Aviation 1 July 29th 03 06:57 AM


All times are GMT +1. The time now is 02:17 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 AviationBanter.
The comments are property of their posters.