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#1
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Double Release Failure
It is likely that the probability of an ACTUAL double release failure on
tow is what ever positive number is closest to zero. Of course that doesn't mean that Mr.Murphy can't serve one of these up. I would be interested in hearing any accounts of actual, non-instructor induced double release failures which required either a landing on tow or purposely breaking he rope to end the problem. I would also be interested in any opinions regarding practicing landing on tow to prepare oneself for this unlikely event. (I know that this is or was a required maneuver in some European countries...but is it worth the risk?) Paul ZZ |
#2
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Double Release Failure
On Sep 7, 9:05 pm, ZZ wrote:
It is likely that the probability of an ACTUAL double release failure on tow is what ever positive number is closest to zero. Of course that doesn't mean that Mr.Murphy can't serve one of these up. I would be interested in hearing any accounts of actual, non-instructor induced double release failures which required either a landing on tow or purposely breaking he rope to end the problem. I would also be interested in any opinions regarding practicing landing on tow to prepare oneself for this unlikely event. (I know that this is or was a required maneuver in some European countries...but is it worth the risk?) Paul ZZ OK, I've got two True Stories, although I was not a pilot involved in either case. In the first, an experienced pilot came back from a flight and said he'd had a double release failure. He said that he just put a lot of slack in the rope and broke it. No big deal. In the second, an instructor at my current club tried to simulate this situation and tried to land on tow. During descent the towplane got too far below the glider while they were low and a long ways from the airport. When the rope broke from the excessive slack generated by the situation this fellow had no option except for landing in a farmer's field. We had no functional trailer for the L13, either, so the retrieve was quite interesting. Personally, I've been flying gliders for over 20 years and have yet to personally experience a failure of the release or rope. I did witness another glider have a rope "break" (actually his tow hook came unhooked) at low altitude and make a successful return to the launch point though. |
#3
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Double Release Failure
On Sep 7, 7:05*pm, ZZ wrote:
It is likely that the probability of an ACTUAL double release failure on tow is what ever positive number is closest to zero. Of course that doesn't mean that Mr.Murphy can't serve one of these up. I would be interested in hearing any accounts of actual, non-instructor induced double release failures which required either a landing on tow or purposely breaking he rope to end the problem. I would also be interested in any opinions regarding practicing landing on tow to prepare oneself for this unlikely event. (I know that this is or was a required maneuver in some European countries...but is it worth the risk?) Paul ZZ I had a release failure (mostly) on my Open Cirrus (CG hook) once. I landed one thermal short of home plate at a neighboring glider club (UK). I handed a cheque out the clear vision panel and took a launch. When I got to altitude and distance, I pulled the release. Nothing. I pulled another dozen times in rapid succession, nothing. I called the tow plane on the radio, no answer. Called several more time, nothing. I flew out to the left and waggled the wings, no response from the tow plane. I was hoping he wasn't going to give me the "bugger off" wing waggle and turn back. A few more pulls and it let go thankfully. Next step would have been to put in the slack and break it. Seemed a long time, but really only a few moments. The TOST hook was replaced before the next flight. No broken springs, just wear. So, I guess it really depends on how you define release failure. Frank Whiteley |
#4
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Double Release Failure
Paul,
I was fortunate enough to be trained in this procedure, albeit 35+ years ago. I was at summer camp that Fred Robinson had for kids at Crystalaire. We're jarring a few cobwebs here but if I remember correctly, the glider would decend to a low tow position and use the spoilers for decent. The glider would touch down first but you had to be careful not to stall and drop the towplane in with excessive braking. We had a 1-34 at the time that needed a radio installed. We didn't have a trailer and the nearby radio shop was at a tower controlled airport (KAPC). We called the tower and they suggested that the glider land with the towplane that had a radio. I wasn't old enough to fly powerplanes yet so my father flew the towplane and I flew the glider. The airport was quite large and the flight was uneventful. Bottom line, it's not as scary as it sounds but I would suggest proper training before trying this on your own. Is anyone teaching this anymore? Barry |
#5
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Double Release Failure
*Is anyone teaching this
anymore? Barry Sure. It's a good exercise for proficiency and confidence building. Touch and goes, taxiing and even turning at runway intersection to take off on a different runway. Good communication, experienced tow pilots, proper conditions, FUN! |
#6
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Double Release Failure
On Sep 7, 11:21*pm, wrote:
**Is anyone teaching this anymore? Barry Sure. *It's a good exercise for proficiency and confidence building. Touch and goes, taxiing and even turning at runway intersection to take off on a different runway. *Good communication, experienced tow pilots, proper conditions, *FUN! Why all CFIG's (in the USA) must discuss and teach this maneuver: It appears in your FAA Practical Test Standards (PTS) for Glider "checkrides" under the Area of Operation "Launches and Landings"/ "Abnormal Occurrences" / "Glider and towplane release failure" (meaning both releases fail.) This is one of five listed abnormal situations in your FAA PTS. FAA allows the Examiner to ask you to perform this maneuver, as the Examiner may ask you to perform any or all of the tasks under "Abnormal Occurrences." Most Examiners just ask for the "towline break" demonstration and the "glider (only) release failure" signal on tow, but "double release" is part of the PTS, so be prepared to at least discuss the procedure on your checkride. Note to CFIG's: Just because a double release failure is rare does not mean you can skip over it in the PTS. The FAA discusses double release failure in the FAA Glider Flying Handbook, Chapter 7. Not much of a discussion however, but there it is. Towpilots need to be thoroughly briefed by a towpilot who has flown this maneuver. The descent is very gradual at a proper approach airspeed. If the approach doesn't look or feel right, the towpilot has the option to go around and climb with glider still in tow. Note to Readers: My discussion posted here is abbreviated and not complete and not to be substituted or used for any aspect of your ground and flight instruction. This post is discussion, not instruction. Regarding the glider in "low tow" position: Because the towplane is gradually descending the wake is relatively higher, so the glider does not need to be too low in relation to the towplane. The sight picture is usually not as low as when you box the wake -- just enough to be just under the wake, and with a full view of the towrope. Keep the airbrakes unlocked and deployed as needed to keep a tight towrope at all times. Overrunning the towplane is the dangerous part both in the air and on the ground roll out. Be ready to release. Important Timing Aspect: The glider (in low tow) must not touch down much before the towplane -- this can be a hazardous aspect -- touching down well before the towplane and stalling it. The glider wings are still carrying the weight of the glider while it is flying. Once the glider touches the wings stop lifting and the glider creates more weight drag on the towplane, which if still well above the runway will be slowed and may stall. If you try this maneuver, keep the glider flying until the towplane is about one meter above the runway. Make sure the towpilot keeps the towplane moving forward (no brakes) with some power to help keep the rope tight. Glider pilot deploys nearly full airbrake (spoiler) to keep from lifting off again and some wheel brake, AFTER the towplane is on the ground. Just roll out and not be in a hurry to stop. Both pilots should release if slack rope develops. If lots of runway ahead a touch and go is possible. Long runways and a good headwind make landing on tow a bit less challenging. A long towrope may be a good idea. For the most comprehensive discussion and training on landing on tow, along with purposely breaking the towrope, contact Cindy & Marty at Caracole Soaring in California. They have developed this procedure to be relatively safe, and fun. Remember, I am not your personal Flight Instructor here. My discussion posted here is abbreviated and not complete and not to be used as part of your ground and flight instruction. For more instruction in "abnormal occurrences" on tow consult with your local Certificated Flight Instructor, one who is proficient in landing on tow. You, your Flight Instructor, Towpilot, and FAA Examiner must determine the level of acceptable risk when performing this or any maneuver. You decide if you want to fly a "landing on tow", and don't blame me if you screw it up. |
#7
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Double Release Failure
On Sep 8, 7:13*am, FBCompton wrote:
On Sep 7, 11:21*pm, wrote: **Is anyone teaching this anymore? Barry Sure. *It's a good exercise for proficiency and confidence building. Touch and goes, taxiing and even turning at runway intersection to take off on a different runway. *Good communication, experienced tow pilots, proper conditions, *FUN! Why all CFIG's (in the USA) must discuss and teach this maneuver: *It appears in your FAA Practical Test Standards (PTS) for Glider "checkrides" under the Area of Operation "Launches and Landings"/ "Abnormal Occurrences" / "Glider and towplane release failure" (meaning both releases fail.) *This is one of five listed abnormal situations in your FAA PTS. *FAA allows the Examiner to ask you to perform this maneuver, as the Examiner may ask you to perform any or all of the tasks under "Abnormal Occurrences." *Most Examiners just ask for the "towline break" demonstration and the "glider (only) release failure" signal on tow, but "double release" is part of the PTS, so be prepared to at least discuss the procedure on your checkride. Note to CFIG's: *Just because a double release failure is rare does not mean you can skip over it in the PTS. * The FAA discusses double release failure in the FAA Glider Flying Handbook, Chapter 7. *Not much of a discussion however, but there it is. * Towpilots need to be thoroughly briefed by a towpilot who has flown this maneuver. *The descent is very gradual at a proper approach airspeed. *If the approach doesn't look or feel right, the towpilot has the option to go around and climb with glider still in tow. Note to Readers: *My discussion posted here is abbreviated and not complete and not to be substituted or used for any aspect of your ground and flight instruction. *This post is discussion, not instruction. Regarding the glider in "low tow" position: *Because the towplane is gradually descending the wake is relatively higher, so the glider does not need to be too low in relation to the towplane. *The sight picture is usually not as low as when you box the wake -- just enough to be just under the wake, and with a full view of the towrope. *Keep the airbrakes unlocked and deployed as needed to keep a tight towrope at all times. Overrunning the towplane is the dangerous part both in the air and on the ground roll out. *Be ready to release. Important Timing Aspect: *The glider (in low tow) must not touch down much before the towplane -- this can be a hazardous aspect -- touching down well before the towplane and stalling it. *The glider wings are still carrying the weight of the glider while it is flying. *Once the glider touches the wings stop lifting and the glider creates more weight drag on the towplane, which if still well above the runway will be slowed and may stall. *If you try this maneuver, keep the glider flying until the towplane is about one meter above the runway. *Make sure the towpilot keeps the towplane moving forward (no brakes) with some power to help keep the rope tight. *Glider pilot deploys nearly full airbrake (spoiler) to keep from lifting off again and some wheel brake, AFTER the towplane is on the ground. *Just roll out and not be in a hurry to stop. *Both pilots should release if slack rope develops. *If lots of runway ahead a touch and go is possible. *Long runways and a good headwind make landing on tow a bit less challenging. *A long towrope may be a good idea. For the most comprehensive discussion and training on landing on tow, along with purposely breaking the towrope, contact Cindy & Marty at Caracole Soaring in California. *They have developed this procedure to be relatively safe, and fun. Remember, I am not your personal Flight Instructor here. *My discussion posted here is abbreviated and not complete and not to be used as part of your ground and flight instruction. * For more instruction in "abnormal occurrences" on tow consult with your local Certificated Flight Instructor, one who is proficient in landing on tow. *You, your Flight Instructor, Towpilot, and FAA Examiner must determine the level of acceptable risk when performing this or any maneuver. *You decide if you want to fly a "landing on tow", and don't blame me if you screw it up. How much runway do you normally consume before both towplane and glider come to a safe stop? I realize field elevation, density altitude, wind, obstructions, type of towplane and glider, are all variables. We have a 3000ft dirt strip at 780ft MSL field elevation, but have barbed wire fences to clear at both ends and a ditch on one end. Is that enough to do it comfortably? |
#8
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Double Release Failure
Just to add two thoughts- 1) the wake is more mild as the tug is
generating less power, 2) it worked best for me (and this is how I was taught) if the sailplane controls the descent rate and the towplane controls the speed. This division of duties prevents the towplane from landing too short. Also, at towplane final approach speed, the glider will be well above stall and clearly not ready to land. Thus it is natural for the glider pilot to keep it flying and apply just enough spoilers are needed at this point to keep the rope taught. The maneuver is uneventful if properly planned out, but it does eat up lot of runway. Chad 4Z |
#9
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Double Release Failure
At 14:13 08 September 2009, FBCompton wrote:
Important Timing Aspect: The glider (in low tow) must not touch down much before the towplane -- this can be a hazardous aspect -- touching down well before the towplane and stalling it. The glider wings are still carrying the weight of the glider while it is flying. Once the glider touches the wings stop lifting and the glider creates more weight drag on the towplane, which if still well above the runway will be slowed and may stall. This seems counterintuitive to me. When the wings stop lifting, the induced drag goes away, so the drag on the towplane should decrease. The only added drag is friction in the glider's main gear. What am I missing here? Jim Beckman |
#10
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Double Release Failure
On Mon, 7 Sep 2009 20:46:08 -0700 (PDT), drbdanieli
wrote: ... text deleted ... Bottom line, it's not as scary as it sounds but I would suggest proper training before trying this on your own. Is anyone teaching this anymore? Barry I don't know about today, but AC Williams and his instructors at Southwest Soaring outside Dallas, TX would frequently do the landing behind the towplace with his Grob 103's during flight reviews. I did a few during BFRs in the late 80's and 90's. Mostly a non-event. The only difficult part I found was coordinating the ground deceleration so as to avoid overrunning the towrope on the rollout. Bob |
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