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SOS - SOME NEW TECH'S DATA !

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SOS - SOME NEW TECH'S DATA !

Δημοσίευσηαπό vagos » Τρί Ιαν 20, 2015 9:47 pm

Τα παρακατω τα μεταφερω απο διεθνες φορουμ , και ειναι η απαντηση-ενημερωση σε ερωτηση μελους του PGF ,απο τον σχεδιαστη και test pilot της ΝOVA.

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"harryab1234 wrote:
It felt a bit sportier than the Ion, more direct and had more energy for wingovers etc. but was a lot more dynamic after collapses. I pulled a fair few 50% and 100% collapses and they were mostly fine but I felt i needed to use a bit of brake to keep them under control whereas with the Ion I would have been happy to let it sort itself out. It also horseshoed a couple of times after frontals which needed a bit of brake to open up again, I'm not sure if this is the wing or if I just wasn't collapsing the tips completely."




Hi Harry,

Thanks for your video, which is perfect to explain a couple of things.

First of all it's quite difficult to completely collapse the tips on the Mentor 4, when inducing a frontal collapse.
The reason for this is easy to explain:
If you look at the attached .png file (on bottom of the posting), you see that there are two A (and B-) lines, which are attached to the stabilo line. (which is attached to the B-riser)
So if you pull the A-risers, the wingtip is not affected.

However, it's possible to collapse the wingtips, if you pull the A-risers quite strong, and not only downwards but also to the inside.
This video shows a frontal collapse from one of our test-flights:


You might notice, that the pilot doesn't pull straight down, but also inwards.
That would be the proper technique to induce a full frontal collapse on the Mentor 4.

Without this technique the wing-tips tend to stay more or less open. So they simply continue to fly, while the centre wing is collapsed. If you scroll to 00:50, you see the most obvious example from your video:


Your reaction is perfect: A short brake input on both sides, to prevent the tips from moving further forward. Like that you exclude the possibility of a cravatte!

A "real life" frontal collapse, induced by a turbulence, is quite different:
First of all the turbulence doesn't care, if the wingtips are attached to A-riser, or to the B-riser. So in "real life" the wintips of the Mentor4 don't have more tendency to stay open than the wings centre. (In fact it's the opposite: The angle of attack on the wingtips of the M4 is considerably smaller than on the wings centre, so the tips will collapse more likely)

Secondly, every turbulence is different from another: Often the frontal collapse won't be symmetrically, and sometimes the turbulence will hit the centre wing more than the tips, so the result might look similar to the frontal collapses in your video.
Here is such a real life collapse of a Ion1 (which, by the way has a high angle of attack on the tips, contrary to the M4):


The lower the aspect ratio, the lower the risk of having troubles (like cravattes) in case of a completely passive pilot, like the pilot in the video.
The higher the aspect ratio, the more it is important to react to collapses. (exactly the way you did in your video)

Some schools or trainers teach to stay completely passive in case of frontal collapses. We at Nova don't like this idea and we've made a short and simple video (showing a Mentor3) some time ago about this issue:


The importance of not staying passive strongly depends on the aspect ratio, like I already explained:
If you just "wait and hope" after a frontal collapses with a high aspect ratio wing (let's say AR bigger than 6) it is very likely to end up with a cravatte.
On a very low aspect ratio wing (lets say AR 5 or below) you will get away with "waiting and hoping" in most of the cases. (Still, the height loss could be reduced, by applying brakes.)

The Mentor is somewhere in between.

Thanks again for your video.
I also like it, because you mention, that you fly a "high-level B wing" for the first time.

Cheers,

P.
lines.png


Υ.Γ :

Το να δοκιμαζεις κλεισιματα σε μια συγχρονη πτερυγα (με λιγα κρεμασματα/σχοινια) δεν ειναι πια οσο απλο ηταν παλαιοτερα. Οχι δεν ειναι πιο δυσκολο , απλα πρεπει να ξερεις καλα τι κανεις ή να εισαι υπο τις οδηγιες καποιου καλου γνωστη - εμπειρου εκπαιδευτη.

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vagos
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