Snao G's

[Ed Deaver]

So, if I am interpreting these numbers(realize only one day and flight) correctly.  Beings the straight and level pos snap at 100mph(not unusual speed) was -13G's and the Rev avalance at approximately 95mph was -13G's, then the forces are about the same.  
 
So, if we can slow the rev avalanche down to 70mph then the G's would only be -7.  
 
This seems to go along with previous arguments that speed is the key.
 
My question is, if the G's on flat and level snaps are approximately the same, with approx equal speeds, as the rev snap, then why hasn't FAI pilots been breaking planes with the 1.5snapopp 4/8????  
 
Before anyone says it, I have seen many of these 1.5 snaps flown with some speed, so they weren't just puttputt into it.
 
Thanx Earl.  Interesting stuff
 
ed


Earl Haury <ehaury at houston.rr.com> wrote:
FWIW, I took a quick look at some snap G's yesterday. Equipment was a Quique YAK (140 size) fitted with an Eagle Tree Systems datalogger with G sensor. I only gathered data from one flight - so take that into consideration.
 
Flat and level pos snaps @ (nominally) 100mph = 13G, dropping the speed to 70mph = 7G. (A normal pull to vertical @ 100mph = 7G.)
 
An Avalanche with a neg snap at the top measured -5G @ 50mph.
 
A Rev Avalanche with a pos snap at the bottom measured 13G @ 95mph. (Masters maneuver - intentionally flown fast.)
 
An Avalanche from the top (push - F05) with a neg snap and a half at the bottom measured -14G @ 90mph. 
 
(I normally measure around 5G on upline and downline snaps with my Partner.)
 
All snaps were executed with rapid / high degree elevator lead and % reduction of elevator during rotation.
 
I may look at this further as the mood strikes. As expected, controlling speed into snaps is easier on your airplane. None of the observed loads (in my opinion) should damage a well constructed aerobatic model (wouldn't want to ride in it though).
 
Earl
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