Why is my glider flying so fast?

Please tell what happened and how it might have been avoided. Names should be ommitted. This forum should help others learn from mistakes that caused or nearly caused a mishap.
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Chip
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Why is my glider flying so fast?

Post by Chip » Fri Dec 15, 2006 7:51 pm

Back in september, I had a less than perfect landing clipping a fence with my left wing tip ........... leaving myself with NO margin for error as I came into a small field to land ( I was leading the competition up until this point).

I survived and so did the glider although I needed about a month and a half for my wrist to recover and the glider needed a bit of repair on the leading edge (sail rip from the fence).

The sail went to WW for the repair, I removed the sail myself figuring it was a good opportunity to get to know all the details of my gliders internals. For the most part this has been true. WW did a fine job on the repair as it's barely detectable unless you're looking for it. When the sail came in I put it on the frame, I had plenty of help in the LZ and I took my time committed NOT to fly that day. My only focus was to put the sail on and adjust the sprogs if they looked like they needed it. When the sail was on everything looked good and I was pretty happy with myself.

I test flew the glider the next day and much to my surprise the glider was even faster than I remembered. Now I know my wrist was not nearly as strong as it had been but this glider was on rails. When I pulled the VG on the basebar wanted to keep going, and this was only with 1/3 of the VG pulled. Matter of fact I was pushing back at the bar so it wouldn't go further than my bellybutton. I let up on the VG and flew around a bit more trying the VG from time to time with the same results each time. I decided to check the speed range but still I didn't go beyond 1/3 VG. I couldn't believe how fast this glider was picking up speed. At this point I figured my sprogs must have been WAAAY to low. The rest of the day I flew with no VG. All of the handling aspects of the glider other than the speed seemed OK.

I flew the glider one more time in this configuration to make sure I wasn't just being a chicken, nope it's going way too fast (I recorded 70, I had never seen speeds like that before). Soooo, I figured the sprogs needed to come up (significantly), I brought the inboards up 3 turns and left the outboards in their current position (thinking the inboards would have the greatest effect). After flying the glider again, I didn't notice any difference. I still had to push the control bar forward to keep it from going past my belly at 1/3 VG. This is crazy I thought. I couln't image that the sprogs had moved that much during the re-assymbly. I was certain that I measured them correctly counting threads before and after. I resigned myself to bringing up the outboard sprogs 2 turns, which I did, but still this didn't set well with me because I knew I set them right before.

All the time this is going on the Khazakstan video is going through my head, thinking, will I be next? This just isn't making any sense to me. But, I'll test fly it one more time. But before I did my test flight with the outboard sprogs brought higher, I recalled reading a post on the OZ Report from Nick Palmer that described my problem nearly exactly. I decided I better check to see if I had accomplished the same mistake. First I referred to the manual and really didn't need to look any further. Once I saw the manual I knew I had misconfigured my attachment points. Seems like Nick, I had placed my sail attachment on top of the LE instead of the bottom near the outboard leading edge. This allowed the tip to rotate downward too far as the VG was applied.

Today I corrected that problem and the glider flew much more like it should, full VG was somewhere just past my chest but the bar didn't want to keep going like before. I'll be checking the sprogs over the next few flights for correctness but at this point I'm not feeling quite as divergent as I was before.

Moral of the story ......
RTFM !!!!! :roll:

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Vrezh
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Post by Vrezh » Sun Dec 17, 2006 10:51 am

:o

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Lucky 13
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Post by Lucky 13 » Mon Dec 18, 2006 1:48 pm

That same thing happened to me when I was flying my Falcon 1. I was going like 70 mph, and I started freaking out, but then I realized my airspeed indicator was upside down.

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Don
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Post by Don » Mon Dec 18, 2006 3:35 pm

Lucky 13 wrote:That same thing happened to me when I was flying my Falcon 1. I was going like 70 mph, and I started freaking out, but then I realized my airspeed indicator was upside down.
Good one Chris ! :roll:

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stebbins
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Post by stebbins » Wed Dec 20, 2006 9:19 am

I had a similar thing happen to me when I reassembled my glider in Florida for a competition. The 1st time I flew it, I knew it was wrong. I had put the tip-attachment webbing over instead of under the leading edge. Or was it under instead of over? ;-) Luckily I did it the same on both wings. Can you imagine what it might have been like if one wing was one way and one wing was another? Scary. In any case, it was simple to fix, and I learned a lesson. I used a permanent marker to mark the leading edges so I now would have to REALLY mess up to do it incorrectly. There is a pathway on the leading edge now that is where the webbing goes. It would be hard to mess that up.

I'm glad you are ok, Chippy! (And I wish I'd heard your story sooner, I could have given you the benefit of my mistake.)
Fly High; Fly Far; Fly Safe -- George

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Post by greblo » Thu Dec 21, 2006 10:46 am

Jeff;
For the benefit of others...
The result was to rotate the trailing edge downward, reducing twist (washout) and causing much more lift at the tips. This extra lift is rearward of the cg and therfore will rotate the nose down in flight. You're also correct in worrying about pitch stability as this washout plays a large role here.
This mistake is so easy to make that it's one of the reasons that most dealers want to set up the glider and tension the wings before considering the repair complete. It can add another half hour to the labor costs, but that's a small price to pay for the added safety. On most gliders the problem becomes visible during the pre-flight, but on our more advanced gliders, it's a lot harder to discover.
Wills Wing requires parts be delivered through a dealer. They recognize that if they facilitate pilots in doing their own repairs, far more of these incidents are likely to occur. This doesn't guarantee that the dealer won't make an error also, but they are much less likely to make mistakes.
My best advice is that pilots think twice before doing their own repairs and to know your glider so well that you can spot even small things that have changed or are out of place.

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