Saturday, March 09, 2013

Delta2 Review

Hi, this is Rick, the pilot in the video.  The popularity and great interest in the Delta 2 deserves a few comments about my flight and my impressions of this excellent new flying machine.
Having just read the info section from the Ozone homepage, I have to agree on several points, especially the ease of control while flying this wing.  Being exclusively used to only higher-aspect, EN-D wings, the Delta 2’s responsiveness to turn inputs was immediately obvious.  This comes very useful in Japanese areas such as the one in the video (Zojiro in Miyazaki Prefecture, my favorite area in Kyushu), where we do much turning in small thermals very close to the mountain.  It was extremely calming to feel the glider turn agilely at that moment we all know well: facing downwind into the hill with the slope closing in fast.  The difference was so significant that it changed my top-out strategy and I began looking intrepidly for small, punchy ground thermals moving toward the ridgeline.  I realized that glide and speed performance aside, due to its extra turning agility in this close-to-the-treetop scenario the Delta 2 was superior to any EN-D wing I’ve tried so far.
The brakes were light to the touch, but with ample feedback for the first 30 cm or so, and usefully resistant to further pulling as if to remind the pilot that such aggressive yawing commands should only be made when desperately needed.  The subtly responsive brake action reminded me of the LM4 which I test flew a while ago, but of course the Delta 2 had none of the high aspect characteristics of wanting to suddenly spin out if over-controlled.  And though I flew the glider aggressively for most of the flight, I never did pull the toggles down to the level of the carabiners, which is something that I regularly do with my own gliders.
The Ozone homepage also mentions that the Delta 2 does not have a tendency to shoot while launching.  I was not able to verify this as I took off into very twitchy air and the glider did overshoot once just before I became airborne and then again a second or two later.  Though the canopy is outside the frame, the aggressive control inputs that were required are clearly visible in the video.  I am fairly sure both of these pitch oscillations were due to the lively ground thermals rolling up the sunlit mountain slopes and not inherent to the glider itself.  In any case, having to control so aggressively during the first few seconds of flying a new wing might have made one feel nervous. But the glider responded splendidly and the accurate feedback coming back down the brake lines actually felt very reassuring.
By the way, the massive collapse shown in the video was due to my own poor skill, over-controlling the glider while exiting a trial set of wingovers.  The glider’s agility surprised me and somehow it and I both ended up deadpointed in the air at exactly 90 degrees of bank.  No amount of control would have been effective as the wing freefell onto its right tip, so I made no input and just watched it happen.  The next surprise was the ease and smoothness with which the collapse sorted itself out, again with virtually no input:  from inside out, gently and predictably, without popping or any violent reaction, allowing the glider to return to straight and level flight without any residual pitching.  I believe this is due to the unique layout of the leading edge battens as well as the shark-nose intakes, which seemed to allow more air to enter the wing during the high angle of attack phase of the recovery.
Due to the unpredictable and unknown movements of the air we fly through, it is extremely difficult to estimate the speed, and especially the glide performance of any wing, and as a certified physicist I would really like to see the ‘scientific’ methods used in deriving some of the published (to 2 decimal places!) glide ratios out there.  Bullocks, I say, unless you set up the whole rig in a giant wind tunnel.  That said, the performance of the Delta 2 seemed pretty much on par with my slightly slow but ‘lifty’ 2-year-old EN-D wing.  Speed bar performance was solid and the C-riser handles were very convenient as I am used to holding onto and controlling with the C’s anyway whenever I use the speed bar.  Too bad the air was not turbulent enough to give a chance to test the action of the handles.  In any case, given the extra stability and agility I felt with the Delta 2, I would swap my glider for it on any XC where rough air or scratching in weak lift was anticipated.  Out-and-return or triangles may be the only cases where my own glider might be slightly superior.
After 2 hours of soaring, having become more or less used to the wing, I took a deep breath and once again attempted some wingovers.  The Delta 2’s agility meant the rhythm of the wingovers was significantly faster (and therefore more difficult to guide) than what I am used to, and within 2 swings I was already seeing the entire canopy well below the horizon.  I proceeded to perform a set of the biggest wingovers I’ve ever done, and reviewing the video, I was excited to see my own shadow sweeping over the wing’s surface several times (I was too busy and/or startled to notice this in real-time).  Due to the faster rhythm I tended to be late on the brake, resulting in a very high apex and the canopy just about deflating. Nevertheless, compensating with aggressive yawing just before the deadpoint getting the leading edge aligned nicely with the horizon, followed by brief, full-on braking on both sides at the moment I was swinging above the canopy, resulted in clean exits with not so much as a slightest collapse.  What fun!  Knowing better this time, I exited the maneuver with a brief spiral and horizontal turn, bleeding off the energy easily and smoothly.  The Delta 2 made even my pathetic acro skills shine!
What can I say?  I love this wing.  Too bad I am dirt poor and can only afford hand-me-downs.  The Delta 2 is so loveable, I can just about kiss any chances of grabbing a used one good-bye, even a couple years down the road.  And since I fly about 350 hours a year in all kinds of places and weather, I wonder how long one would last in my hands anyway, with its extra skinny lines and snazzy lightweight fabric (holding the lines together at launch, it felt like a whole riser set was missing).  I can only dream of being a idle rich bastard, ordering a fresh one about every 6 months.  Alas, with my current lifestyle, such a thing will never happen.  Maybe now that the Delta 2 is out people will upgrade and part with their beloved original?  M-size, please?


  • Hi! Rick

    I'm Toyooka, a flyer fLying in Aso.
    Thank you for your nice review.

    I sometimes flew behind you and studied by seeing your flight.
    You are nice teacher!
    Good flight technique and flight plan.

    Some flyer are planning flying from Aso to Beppu.
    But noone complete.
    Let's fly together to Beppu.
    See you again in Aso.


    Thank you for your patience about my poor English.

    By Anonymous Toyooka, at 10:20 pm  

  • Hello Toyooka-san,
    Thanks for your kind comments. Your English is great. Yes, the Aso to Beppu flight is a great and difficult challenge. I am reviewing the weather conditions every weekend for a suitable day to try it. When it looks good, i will post the forecast on the KuratakePara bulletin board: where i usually post forecasts for every wekeend.
    definitely let's try to fly it together soon. spring is probably the best time!

    By Anonymous Rick, at 11:29 pm  

  • Rick-sensei

    I will check the bulletin board every Friday.
    But I have to work every Saturday.
    So I sometimes coudn't get a chance to fly over Mt.Kuju.

    Actualy, Spring is the best season to fly to Beppu. I think so too.

    I'll looking forward to your post.

    By Anonymous Toyooka, at 10:41 am  

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