I was flying gliders in the 1990's. We had mostly plywood and doped fabric gliders. It was the rule on DI's that one drew a pencil-line at the farthest extent of a crack, and dated it, so that the rate of crack propagation could be seen. One day, I grounded one of the gliders, only for someone to remark "but it's been correctly dated". I countered "but it's an EIGHT FOOT LONG CRACK! Suddenly, those present looked appalled, because they'd managed to over-look this, secure in the knowledge that what was required had been religously observed!
I think Ben Hughs learned from you. It ever fancy giving giving us anything that would be great. Your stripping the gel off a fuselage would be great on you tube!
There are electronic stethoscopes available for automotive diagnostics. Allows you to listen to a part while driving. They will probably work well for listening to different areas of a sailplane during inspection. You can put a suction cup or cups for the multi channel ones and then go and push and pull on different areas listening at the same time. I have always found it easier to associate the noise with the input action for diagnosis. The sensitivity is amazing over the non-electronic versions. Silence is in these cases, is golden.
I do not fly a sailplane, nor do I fly any kind of plane apart from a bit of RC. But Sir, your video is very interesting and now I now for what damage to look for if I will fly in a sailplane :D Great Video :)
Very vey informative indeed. Chapeau. 1. Is 125 kts a comparative low speed for such a fast glider? A Ka 6 can fly that too ( and is allowed to do so) Was the Nimbus 3 pre-delaminated, such as the Nimbus 2.? It must be! 2. A tap test often will find an issue as well... is stated. Read my contribution on this topic. Using a 100 gram steel bolt with a large radius rounded tip is very discriminative to find delaminations. Just let it swing with a loose wrist, using say 2 Hz. Check ever rib, spar etc and listen to the sound. Clear is OK, dull is delaminated. I did inspections on gyrocopter rotorblades and could find some delaminations of 1/4 inch (minimum detection limit). I made a chart using transparent paper to map the delaminations. The delamination were smaller than 1/2 inch, so no show stopper. After some further flying I tapped the blades again. Laid the transparent chart on the blade and indeed, the delamination were larger, the had grown. We rejected the blades for further use. ( no blade = no flight ) Thanks for the clip.!
Excellent little clip this, Gordon, but, around the 1 minute mark, you mention 'fin flutter' - do you know the cause of this flutter? May the underlying damage have cause the flutter or did the flutter cause the damage you go on to describe? Thx for these, keep up the good work!
Wait what ? How are you going to bail out established final in a glider ? Or you mean he could have zoomed high with his excess speed, then bailed out ? Really ?
The pilot was recovered to 2000 ft above ground after the flutter occurred. He was not near the ground when it happened. He immediately slowed down to less than 50knots, and evaluated the handling before continuing his now slow final glide back to his home airfield. But the fin could have fallen off at any moment, a bit more yaw, roll or pitch load (or a combination of all 3) in the wrong direction would have broken what little skin was holding it on. In my 40 years as a repairer I have seen pilots stay with broken gliders after inflight problems or collisions. 2 I know did not survive. After recover back to level flight, that decided to land, but the tails failed in circuit, too low for bailout in a rapidly accelerating/tumbling glider with no tail. Personally, based on the UK law of averages of emergency parachute failures verses trying to land with unknown damage after a collision or failure. The parachutes offer a better chance of survival on average.
Gordon - change your RU-vid channel profile. You have it setup as "made for kids" this keeps us from being able to subscribe to your content when it is uploaded. The content can be kid friendly - and not "be made for kids".
The Astir I am told did fly once. The elevator damage was hidden by Mylar and they did not put any stress on the tip of the tailplane to see the flexibility. There were no external cracks at all. But a thorough pre flight inspection would have found the damage. ASW24 and Nimbus 3 both flew with damage because the owners and engineers did not see spot it. In both cases there were zero cracks on the outside. The ASW 24 also passes a tap test. Only by comparing it to another ASW24 that had a stiffer fin was the damage found. These videos are real world broken gliders, that professional sailplane repairers have sent me, to help educate owners and engineers on damage that has been missed.
