Friday, September 11, 2020

Tuning, and fine tuning...

Dear friends and fellow pilots, 

After some years of test flying many gliders from practically all categories, I felt that I needed to share with you some important issues. 

At first, I like to point out that the tests that I do could be called "macro testing' As many of you know that these tests are made in very specific sites, that allow us to see the tiniest difference in performance between gliders. those sites offer sometimes humid conditions and heavy air with a sea breeze. And sometimes experiencing an easterly stable layer that makes an A glider difficult to handle. Those conditions could be found anywhere near the sea, like Greoliere or Gourdon in summer …etc….It’s like runners competing in the mud. The most complete athlete will prevail. When flying in different places where all those effects are not present it would be more difficult to see the difference. 


But over the years, I experienced lots of other things that I need to share with you. 

I always fly the gliders at their optimum weight load. (how do I know the optimum weight?)   Easy: When that glider will surf effortlessly at a certain load the ‘difficult ‘ airmass while being still good in weak thermals. The balance is the optimum weight. 

Usually, ninety percent of gliders like to be loaded to fly properly, but some like the Maestro and Allegro like to be flown slightly above mid-weight while staying good in moving forward.  


As many pilots are looking for performance, 90% of manufacturers are going extreme in using the line width, that offers safe usability within the certification protocols, and offers the minimalistic drag for optimum performance. 

Those lines have accurate and defined measurements, and sometimes much less than one cm of length could make a difference. Tuning them properly in order to insert that glider into a certain box (A, B, C, D, or CCC) 

I saw on many occasions that the lines on the newly released B, C, and D gliders move after 'sometimes' 30 hours! Even on some B’s! 

So, depending on the glider.  That's vercommon on 2 liners as many of you already know. 


In most cases, after 50, to 60 hours 90 % of the B, C, or D gliders have a different 'feel a different 'trim speed and in most cases, a better climb rate'. Probably the glider becomes slower and sometimes climbs better, but wind transitions also will be different and sometimes are penalized. 

I also knew that a slight tolerance of a few millimeters is permitted within the certification.  

Now, that means that tests about performance could change slightly! 


Today's gliders are very sophisticated pieces of machinery. 

And little adjustments could alter ‘slightly’ the feel and performance.  (It doesn’t matter for many! ) I know, but I must write it as it is. 


Another important issue is that when a brand new glider is released, after certification, and after some 360s and some flying hours, the lines are well placed, and that glider could offer the exact gliding properties that the company intend to deliver and a very specific dynamic behavior through the airmass.


Sometimes, I get another glider for the same brand and the same size and I find loops on the B's or on the C's! It happened to me with the Q-Light S. The first one had incredible flying properties, and the second felt slightly less. The second had a loop on the B's. After asking the manufacturer about them, they said that this configuration is more comfortable for the pilot. They were right. But the flying quality was lesser. I released the B loops, and I regained that beautiful feel. The same happened on the Mantra 7 MS. When releasing the B loops, (about +0.8cm ) the glider became more dynamic and better feel through the airmass. But it was slightly more handful to fly, and also the Q-Light S. 


The Fusion M size didn’t have a loop on the C’s. It had superb flying qualities.  The Fusion S,  I purchased for my tests, had loops on the C's when it arrived. After my test, I concluded that it was comfortable but still needed that extra surfing into the wind. 

 After 60 hours, the dealer got an email from Flow to release the C loops on his Fusion S, Light ( specially made for him).

 The feel of surf and climb in those 'macro testing' facilities were much better! The Fusion S seemed to breathe more the air and the overall performance in moving air matched the best C's of today!  


The first Delta 4 MS I had was incredibly good! It was one of the first demos that was already flown a bit at Ozone, and it flies superbly well!  The B risers were matching the A and C risers. 

The second one,  B risers were 0.2 cm lower than the A risers. The overall feel if lightly loaded (87 all up for the MS)  was a slow glider in those difficult conditions, but still sharing the top of the C category. Loading in at 94 all up, it regained that surfing upward.

The same risers configuration is on the M7. In time, or after 30…40 hours, the loop on the B link on the Delta 4 can be released. (Ozone already posted something like that on the forum, but better to ask when to release them)  That feel of a slightly liver glider will be available.

The Leopard S,  that was tested earlier, had loops on the B's. Releasing those loops on a new serial model would have altered my test! Just because it was super efficient to dig through the air, a bit more alive, and gave me more feel even in weak thermals. But those loops must be kept at least until the glider needs tuning after some hours or so...probably. (info from Gin) 


The Maestro 21 received a flawless reviewbut the size 19 was so different...and the xalps 19 was even more awkward in feel! 

I needed to share that important information with you, just to tell you that even reading very transparent tests, the result is an 80 % max performance accuracy, and could change!!!  And concerning the handling, “if properly loaded”, an accuracy of  95 % on handling and brake authority. 

I think now you must be lost! :-)  But that is the real thing… 


All those changes that could occur will sometimes get you around +/- 10 % increase or decrease in performance and glider feel and behavior. 

And again, it is probably not important at all.  But I thought it must be said.


When I choose a glider to fly for fun, all that matters for my personal taste is a performance glider that transmits “accurately the airmass and reacts swiftly to any brake input regardless of the conditions.” 

To conclude, a glider that makes me smile after landing is the one I always choose to fly in my day off    ;-). 


Happy flights, 

Ziad 




PS: Please do not alter your glider before getting a professional opinion and a yearly check is advisable.  

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.