A Tale of Two Takeoffs [Archive]

June 17th 17, 12:55 AM

I have a secret.

Well, like secrets in a Congressional Intelligence subcommittee, this one is probably known by several hundred people. But I haven’t written about it. Until now.

But first, the lead in. A few days ago on the last day at the Cordele nationals, I dropped a wing on takeoff. The ballast tanks were half full so although the tip didn’t go down hard, the water sloshed in that direction and the wing stayed down. My ASW 24 started to swing off to the right. I wasted no time in pulling the tow release. The glider continued to swing and I braked as I rolled off the asphalt runway into the grass and stopped.

No big deal. I’ve had a rule for many years that if the wing goes down early with ballast, I release. It's almost impossible to get the tip up again (more later). I’ve done it twice before--both times on grass--and it’s slightly embarrassing but uneventful except for blocking the launch. This time I actually rolled out of the way. Not much more than five minutes later, I had been retrieved with a golf cart, put back on the launch line, and was away without ever having to climb out of the cockpit.

There was a bit of a tailwind (under 5 kts.). But the biggest contributor was a slightly heavy right wing caused by the water not being evenly distributed. I had checked it on the grid but I noticed the girl who (very competently) balanced the wings while the glider launched ahead of me held the right wingtip a bit higher than normal. Just before takeoff, though, she passed it to a young man who actually ran it. In the hurried exchange, it’s possible he leveled the wings, thereby allowing the water to shift in that direction. With partial tanks, any imbalance is quickly magnified although I’ve only touched a wingtip once before in 25 years of flying the ‘24.

Speaking of which, now for my “secret.” Almost exactly a year ago at last year’s Nephi nationals, I had full ballast, a 10 kts.. tailwind, high density altitude, and (I’m told) a very young, inexperienced wing runner. My impression was that the tow pilot stood on the brakes as he ran the engine up, then released them. The rope stretched and we popped off the line impressively, then seemed to sag as the stretch came out of the rope before accelerating again, in somewhat more leisurely fashion.

The initial surge surprised the young wing runner and he held onto the tip briefly, swinging me to the right, before dropping it. The tip hit the ground almost immediately as we gathered speed. I was near the front and knew there was a lot of emphasis on keeping the launch going. This was the first contest day and launching 55 gliders had taken too much time on the practice days. So I felt (self-imposed) pressure to stay on tow. And I felt (again, self-imposed) pressure to recover from what I judged was my mistake.

The wide runway and gravel/grass on the right looked completely clear: I didn’t see spectators, vehicles, aircraft, or other obstructions. So I broke my rule of almost 40 years and held on. I remember thinking “I can do this!” As we accelerated, the glider continued straight at an angle to the runway centerline, drawing closer to the edge. My ship has a CG hitch so with the right wing still down, there was nothing to help straighten us out. With full left aileron and rudder, the right wing refused to come up. I knew the gravel on the edge of the runway and the scrubby grass beyond were smooth. So I held on as we rolled off onto the gravel.

By that time we were traveling fast enough that I really didn't want to release. And I could sense that the wing was just about to pop up. It did. I steered back onto the runway, put the dive brakes in (which I use on takeoff roll to improve aileron response), then lifted off, sliding back into position behind the towplane. My heartrate was a little higher but to be honest, I didn’t think it was that dramatic.

I flew the difficult task and landed back late that afternoon. As I rolled to a stop at the end of the runway, I was startled to see the operations director leap out of his car with a grim look on his face and start snapping photos of my right wing. Turns out I had hit a landing light on takeoff, slightly damaging the leading edge about 2/3 of the way out and punching a small hole in the underside of the aileron. I never heard or felt it! Thanks to the heroic efforts of York Zentner--and with assists from my brother, Mark, and poor weather the next day--I was back in the air in time not to miss any action.

But I was humbled. How could I have messed up so badly? One respected colleague offered that I had failed to have a contingency plan. But that’s not true. I had a plan; I just ignored it.

I could have blamed the tailwind and young wing runner, as another ground crew member did a few days later as we chatted on the line. His inexperience almost certainly triggered the incident. But the fault for the damage was all mine. I could have prevented it by pulling the release. Why didn’t I?

I think it came down to ego. I remembered thinking I had made a mistake in dropping the wing, a mistake I wanted to--and was convinced I could--correct. And I was sure, until I landed that night and even for a few hours afterward, that I had acted reasonably, that the landing light hidden in the high grass was just one of those things that can’t be controlled and that my decision to try to recover from a takeoff gone bad was justifiable. After all, I would have gotten away with it except for the light.

I was wrong. The correct decision was to pull the release immediately, the way I had several times in earlier years and the way I did two days ago. Some decisions are easy: we make them before we fly and all we have to do is execute. Are there times when we should modify our contingency plans due to circumstances? Sure, but we need a better reason than trying not to look stupid or saving a few minutes on the launch grid.

Chip Bearden
“JB”

Echo

June 17th 17, 01:31 AM

Great write-up. I've also learned the importance of a well briefed experienced wing runner, and letting it sit wings level "until the sloshing noise stops" before takeoff. I do have one question, however. How does extended spoilers improve aileron response? They're inboard of the ailerons on a standard class glider, and therefore should have zero aerodynamic effect on ailerons, except for contributing to total drag and reducing acceleration...(probably an impercievable amount at low speeds, since weight and stationary inetia is the larger factor to overcome, not parasitic drag). I've seen many people use this technique in contest flying, and I never understood it. The only argument that I could maybe see is giving some drag stability, much like hanging out the landing gear does to a large aircraft. And even then, it just adds complexity to an already high workload segment of the flight.

Again, I think your post is both informative and a great pointer for anyone staring to carry water ballast or inexperienced in flying a CG hook. I'm mainly just curious as to why people use the spoiler on takeoff technique.

Jordan

BobW

June 17th 17, 02:13 AM

On 6/16/2017 5:55 PM, wrote:
> I have a secret.
>
> Well, like secrets in a Congressional Intelligence subcommittee, this one
> is probably known by several hundred people. But I haven’t written about
> it. Until now.
<Lucid write-up of two wing-drop-included takeoff runs snipped>

> But I was humbled. How could I have messed up so badly? One respected
> colleague offered that I had failed to have a contingency plan. But that’s
> not true. I had a plan; I just ignored it.ng runner, as another ground
> crew member did a few days later as we chatted on the line. His
> inexperience almost certainly triggered the i

>

> I could have blamed the tailwind and young wincident. But the fault for the
> damage was all mine. I could have prevented it by pulling the release. Why
> didn’t I?
>
> I think it came down to ego. I remembered thinking I had made a mistake in
> dropping the wing, a mistake I wanted to--and was convinced I
> could--correct. And I was sure, until I landed that night and even for a
> few hours afterward, that I had acted reasonably, that the landing light
> hidden in the high grass was just one of those things that can’t be
> controlled and that my decision to try to recover from a takeoff gone bad
> was justifiable. After all, I would have gotten away with it except for the
> light.
>
> I was wrong. The correct decision was to pull the release immediately, the
> way I had several times in earlier years and the way I did two days ago.
> Some decisions are easy: we make them before we fly and all we have to do
> is execute. Are there times when we should modify our contingency plans due
> to circumstances? Sure, but we need a better reason than trying not to look
> stupid or saving a few minutes on the launch grid.
>
> Chip Bearden “JB”

Thanks for sharing your experience (and experiences), Chip. I completely agree.

Sharing and discussing these sorts of things is - IMHO - the *other*
fundamental raison d'etre of RAS...as methinks is well-demonstrated by Jordan
Pollock's question (i.e. "How does extended spoilers improve aileron
response?") elsewhere in the thread. It's a question I think I first
encountered in print several decades ago in "Soaring" magazine, and which I'll
toss out for discussion my 2-cent's-worth response. Undoubtedly others will
contribute/elaborate/disagree...all good stuff in principle.

The way I think about raised spoilers enhancing roll response during takeoff
is this: by reducing the amount of total lift the wing is producing, the
"aerodynamic roll stiffness" is reduced, hence any aileron input will have
less roll inertia to overcome. Viola! Improved roll response. (Imagine a wing
infinitely stiff-in-roll at all speeds - there'll be zero aileron effect.)
Others have (and likely will) posit at least one (other/secondary?) effect
related to the changed spanwise flow-field over the wing positively
assisting/improving the ailerons' flow fields (hence improving their actual
"power"). If this is so, I'd expect short-spanned gliders to (painting with a
broad brush, here) to be more likely to benefit from use of the open-spoiler
technique than long-winged birds, because of short-spanners' lower,
mass-related, roll inertia.

FWIW, the same thinking "works" for camber-changing-flap-equipped birds, and
at least for the one in which I have all of my experience, it can be shown to
"work" in reality, as well. Next time you're ground-bound on a day with a more
or less steady 10-15-knot breeze, face your ship into the wind, snag a
wing-tip buddy for a few minutes of experimentation and fun. Have your buddy
level the wing and let go on your command while you attempt to keep wings
level. Odds are you'll find it's easier to do so with
spoilers-open/flaps-negative than not.

Bob W.

---
This email has been checked for viruses by AVG.
http://www.avg.com

[email protected]

June 17th 17, 02:17 AM

Jordan, I have heard several "reasons" for using spoilers on standard class gliders. First of which is that the spoilers "board" the air out ward and increase flow over the ailerons. Second that "spoiling" the lift on the raising wing will let it come back down. I tend to think the first is closer to the truth. But from personal experience in an ASW-19, it works. I didn't really believe it until I tried an experiment. When landing, I put the spoilers away on the last half of the rollout not using the brake untill one of the wings started to drop and I had full aileron deflection in and it continued to drop. At this point I was traveling at around 10-15 mph, when I then opened the spoilers the wing imediately came back up and stayed there until I was down to less than a couple of mph. All I really know is that it works.

gkemp

June 17th 17, 01:22 PM

I flew hundreds of hours in a CG hook Pegasus and never used spoilers during a takeoff. No problems.

gkemp

Dan Marotta

June 17th 17, 04:35 PM

I don't recall using spoilers or not with my ASW-19b (CG hook), but I
always used spoilers and negative flaps with my LS-6a also a CG hook)
and found that to be an improvement. I continued using negative flaps,
but no spoilers, in my LAK-17a (CG hook), and had no problems there, either.

In Chip's case, I agree with his assessment that the main cause of
trouble was the partial ballast load shifting outboard on one side
(inboard on the other).

On 6/17/2017 6:22 AM, gkemp wrote:
> I flew hundreds of hours in a CG hook Pegasus and never used spoilers during a takeoff. No problems.
>
> gkemp

--
Dan, 5J

John Cochrane[_3_]

June 17th 17, 04:40 PM

Spoilers open on takeoff works. Until you're trying to take off high altitude, hot, cross-downwind, full of water, you won't notice the need. Then you will. You get a crucial second or two of better aileron control.

Thanks much Chip for the good post. Wing running is a constant problem at contests. I've had several incidents where despite my careful briefings, contest wing runners just can't get it right. The wings must be balanced, level, sloshed through the baffles, but if there is a significant cross wind (mifflin), the upwind wing cannot be high. You must run. This is not a 2-33. Runway lights make it a higher priority.

It's hard to whine. The wing runners are volunteers, and spending a long hot day running wings for cranky pilots cannot be fun. Still, along with slow tows, this is a constant problem at contests, and perhaps more regular emphasis by contest management would help.

(Why must every contest start with a litany of "towplane alpha bravo, more speed please." "towplane alpha bravo, more speed please.".... )

John Cochrane

Ron Gleason

June 17th 17, 06:27 PM

Yup John you are whining 😀. If you need and desire the best for you, wing runners and tow pilots, you can bring them along or better yet be a wing runner for a contest. All are volunteers and they do the best they can and contest management do the best with the resources available.

John Cochrane[_3_]

June 17th 17, 07:59 PM

Ron:

Thanks, and I really did hesitate to say anything, as I hesitate and hesitate again to complain at contests. On the other hand, we do have a problem of wing drop after wing drop, sometimes causing damage, once causing damage to a spectator, and the problem is not hard to fix. We also have a constant problem of too slow tows with ballasted gliders. Everyone gets used to flying without ballast over the winter I guess.

Perhaps you can help with social suggestions. While showing my deep appreciation for the volunteers and towpilots, who give up their free time and suffer in the sun all on my behalf, how can I get the message across -- wings must be balanced, slosh ballast through baffles in tanks if need be, they should be darn close to level -- which is hard to see given winglets, and a contest glider wing at familiar shoulder height is way too high -- and if there is a crosswind, it is imperative to have the upwind wing at least level if not a foot low at the moment of release. Plus, run. How do I say that really politely, and show the deep appreciation that I really do feel?

It is frustrating to be sitting on the side of the runway, in the dust, bottom of the wing all scratched up, on account of an easily preventable error..

John Cochrane

[email protected]

June 17th 17, 08:42 PM

On Saturday, June 17, 2017 at 11:40:18 AM UTC-4, John Cochrane wrote:
> Spoilers open on takeoff works. Until you're trying to take off high altitude, hot, cross-downwind, full of water, you won't notice the need. Then you will. You get a crucial second or two of better aileron control.
>
> Thanks much Chip for the good post. Wing running is a constant problem at contests. I've had several incidents where despite my careful briefings, contest wing runners just can't get it right. The wings must be balanced, level, sloshed through the baffles, but if there is a significant cross wind (mifflin), the upwind wing cannot be high. You must run. This is not a 2-33.. Runway lights make it a higher priority.
>
> It's hard to whine. The wing runners are volunteers, and spending a long hot day running wings for cranky pilots cannot be fun. Still, along with slow tows, this is a constant problem at contests, and perhaps more regular emphasis by contest management would help.
>
> (Why must every contest start with a litany of "towplane alpha bravo, more speed please." "towplane alpha bravo, more speed please.".... )
>
> John Cochrane

I don't fault the wing runner.
It was Chip's responsibility to have the glider with acceptable wing balance.
Possibly a very experienced wing runner might have stopped this event, but most don't have the experience or judgement.
This is the second case of serious wing drop due to balance at contest I have flown at this year. The other resulted in a glider not flyable.
The lessons I see here:
1-The pilot must be careful to ensure balanced loading.
2-Line crews need to be trained to recognize imbalance and be prepared to stop the launch to correct. The line boss needs to be ready to confirm the problem or declare good to go.
3- We all need to ready and more incline to end a bad start.

FWIW
UH

Echo

June 17th 17, 09:25 PM

That's pretty interesting. Seems incredibly minute, but if it gets results there's not much to argue with. My only point against teaching it is the complexity it adds to a launch, when there's already a lot going on and plenty to be aware of. I can see it needs to be muscle memory. Thanks for the explanation.

Jordan

Echo

June 17th 17, 09:29 PM

While I'm in an inquisitive mood, here's another one. What speed are you flying when you thermal your ballasted glider in a 45 degree bank in a gaggle, allowing for the extra energy required for surprise maneuvering? What speed were you being towed at 15 minutes earlier that resulted in your vhf complaint for more speed from the tug driver? Since you're flapped (I'm assuming), what flap setting are you using on tow? Trying to better understand this...

Jordan

Charlie M. (UH & 002 owner/pilot)

June 17th 17, 09:48 PM

Actually, I consider this incorrect.

When trained for any job, there is a lot to learn. Things like:
Glass ship, dive brakes open, pilot typically HAS to be holding them open. No comment pre launch
Metal ship, dive brakes open, may be by mistake, say something.
Check for tail dolly
Point out other traffic
Etc.

Nut behind the stick is final say.

Example, annual Snowbird contest in Elmira, people talk about practice for the event (look it up for rules and goal). In reality, it is to reinforce energy management for potential off airport landings and proper landing placement. People that have to practice means they are not ready when it happens in the future, but if properly reinforced all flying season you should do well when needed.

Running a wing should be the same every flying day, contest should only get a minor tweak due to a slightly faster than normal launch and potentially higher glider density. Judgement on go/no go by the runner may be hard, but all the other basics should be covered.

Posted by someone that used to work contests (as ground crew, runner, retrieve, etc.) since the mid '70's and contest flying later on. I also do ground duties even now when at the airport.

The old adage of, practice for the worst, hope for the best, comes to mind. If you don't do it all the time, a contest can be a bad place to learn.

Chip, thanks for the thread. It takes some guts to post this in front of some of the RAS crowd. I have had some of my own nail biters in the past, so I understand.

Charlie M. (UH & 002 owner/pilot)

June 17th 17, 09:52 PM

When you're in a ASW-20C @9lbs on tow and you feel like you are always about to stall on tow, that is too Frikkin slow. Yes, been there done that, feigned an issue so I didn't end up behind that tug later in the contest when wet.

Speed in thermal? Sorta depends on if smooth or rough, I don't know, what feels good? As AOA goes up, some airspeeds lose accuracy. If the plane feels happy, then I'm happy.
I'm too busy watching for other traffic and rely on sound and feel, not looking at an instrument that is a second or two behind actual.

firsys

June 17th 17, 09:57 PM

On Friday, June 16, 2017 at 7:55:55 PM UTC-4, wrote:
> I have a secret.
>
> Well, like secrets in a Congressional Intelligence subcommittee, this one is probably known by several hundred people. But I haven’t written about it. Until now.
>
> But first, the lead in. A few days ago on the last day at the Cordele nationals, I dropped a wing on takeoff. The ballast tanks were half full so although the tip didn’t go down hard, the water sloshed in that direction and the wing stayed down. My ASW 24 started to swing off to the right. I wasted no time in pulling the tow release. The glider continued to swing and I braked as I rolled off the asphalt runway into the grass and stopped..
>
> No big deal. I’ve had a rule for many years that if the wing goes down early with ballast, I release. It's almost impossible to get the tip up again (more later). I’ve done it twice before--both times on grass--and it’s slightly embarrassing but uneventful except for blocking the launch. This time I actually rolled out of the way. Not much more than five minutes later, I had been retrieved with a golf cart, put back on the launch line, and was away without ever having to climb out of the cockpit.

Echo

June 17th 17, 10:28 PM

Yeah I'm asking for numbers. I own and fly a ballasted 20. And I've towed my share of contests at Perry and New Castle. I'm asking someone to look in their manual and give me their numbers. I know what the slowest I've towed even a club glider is. I know my 45 degree bank thermal speed full of water.. I still thermal slower than my slowest tow...and towing is a lower bank angle so more margin than thermalling with gliders in 3 quadrants. So the "about to stall" thing on tow is why I ask for numbers. "Feel" is not something I can reference as a tow pilot. If it's for your own comfort, I'd suggest asking for a specific speed. Not "faster." Personally in my 20, flaps 4 and ballasted I feel like I'm standing on my pedals. I usually back off the flap to 3 or 3A once up and settled. Maybe we just tow faster around these parts...

Jordan

[email protected]

June 17th 17, 11:24 PM

I agree, Hank; ballasting was my responsibility. On the grid at Cordele, I removed the wing wheel and double checked, taking time to make sure the water had stabilized and the wings were level. Obviously I misjudged it standing at the right wing because later, after the line crew removed my wing wheel, from the cockpit it seemed like the girl at the right wingtip was holding it a little high (indicating it was heavy). I called out to her over the tow plane noise not once but twice with "Are they balanced?" She nodded the first time. The second time she took her hand off the wingtip to show me ("why doesn't that man believe me?" haha). Since she had the wings balanced, I didn't even think about declining the launch; the line crew had it under control.

I have assumed--but don't know--that when she handed the wingtip to the actual wing runner, that balance was lost. If it looked high to me, it probably did to him. Maybe the slight tailwind contributed. Maybe I just did a bad job on takeoff. Most important, unlike at Nephi, this time I made the right decision and pulled the release. No harm done.

[I'm thinking of using a bubble level or other visual indicator so I can ensure the wings are level when I'm solo. I've seldom launched with full tanks and dumped down; even at max gross the water still sloshes around and the takeoff performance is reduced.]

Agreed, wing runners don't have to be experts but they must know the basics.. And that includes balancing the wings. Even when my tanks are absolutely even, the wing runner still has to make sure one tip isn't lower/heavier than the other. There are no baffles; just two compartments per bag that allow water to flow easily back and forth. It's as important as not letting go of the tip after two steps and not holding back when they can't keep up.

Contest line crews are heavily populated with local kids, many of whom don't have much experience. They're enthusiastic and athletic and they learn quickly. But they have to be trained and supervised. Perhaps we need to add a session for them in the pre-contest briefing where pilots can express their concerns and even demonstrate what works and doesn't work for their gliders.

Some years ago, the young, inexperienced wing runner at a Hobbs multi-class nationals was holding back, steering pilots off course. The problem was the advice he was getting to grasp the wing by both the leading and trailing edges. I didn't want to argue technique on the line so I immediately drafted my daughter, who had never run a wing before. I briefed her for a few minutes, calmed her nervousness, and reassured her she would do great. A 16-year-old high school track star, she ran it perfectly...and was promptly approached by half a dozen pilots to run their wings. The operations director watched what was going on, then quickly recruited her for the line crew. She ended up running wings for nearly all of the crewless pilots at the contest.

This made the contest a lot more fun for Tina, she took home a few bucks from the "pass the hat" line crew fund, and she wrote her college common app essay on the experience, which apparently impressed admissions directors. Soaring is a great sport! :)

Don't just gripe; speak up...constructively. The Cordele line crew did a fine job the past two weeks. But when I observed one of the younger ones struggling to balance a ballasted wing during the pre-contest weighing, I approached the operations director there and politely advised him that many of us would be launching with partial ballast and it was critical to balance, not necessarily level the wings before launch. He graciously acknowledged my concern and said he would make sure the crew were properly instructed. I believe they were.

John is correct. It's hardly whining to suggest there are problems at many contests involving the launch sequence. I've thrashed the wing runner issue to death. Sometimes tow pilots show up who haven't towed a lot of ballasted gliders, or towed at that airport, or whose aircraft have ASIs that aren't spot on. I have to call for "[towplane ID], 5 knots more airspeed, please" at least once a contest.

The next tow I got at Nephi after my incident last year was from the same tow pilot. And, again, he seemed to stand on the brakes while powering up, then release them with a predictable slingshot effect on the tow rope. I sought out the chief tow pilot, asked him about the practice, and diplomatically offered my assessment. He listened thoughtfully and promised to talk to the tow pilot. Whatever was said, if anything, it didn't happen again.

He didn't suggest that I bring my own tow pilot if I didn't like the ones he managed.

We pilots should be proactive in helping organizers address staffing issues.. Pilots certainly make mistakes; organizers do, too. The smart ones accept our criticism and suggestions graciously, decide which ones make sense, and take appropriate action.

Just my opinion.

Chip Bearden
"JB"

Charlie M. (UH & 002 owner/pilot)

June 17th 17, 11:56 PM

So, you're assuming everyone has a calibrated ASI that reads just like everyone else's?
"What's it sound like, what's it feel like"?

I can't answer your question, I'm watching for traffic and the local gaggle when on tow.
I listen and feel for what is correct. When I'm afraid to do anything beyond minor on controls because it may stall, I'm not happy.
Period.
If you need hard numbers, maybe you need more training?

Posted by an ex CFIG for 8 years.

BobW

June 18th 17, 01:36 AM

> That's pretty interesting. Seems incredibly minute, but if it [using
> spoilers early in the takeoff roll] gets results there's not much to argue
> with.

The effect may indeed be minute, and it almost certainly will vary from ship
to ship for a host of subtle, perhaps forever-mysterious, reasons but, "If it
happens, it must be possible!" :) That noted, "safe soaring" is all about risk
management, and risk management is all about maximizing one's margins in any
given situation. By single-main-wheel definition, takeoff in a sailplane is a
low-margin situation (hence the near-universal need for a wing runner), and
anything Joe Pilot reasonably can do to minimize his time at risk is arguably
worthwhile doing.

> My only point against teaching it is the complexity it adds to a launch,
> when there's already a lot going on and plenty to be aware of. I can see
> it needs to be muscle memory.

Ah, yes, a sixty four dollar question: "Where and by whom shall the technique
be taught and practiced?" Beaucoup soaring skills are self-learned/self-taught
(one of the attractive charms of the activity in my view). Arguably a quick
way to kill the sport dead would be to mandate from the top down a list of
things that *must* be taught over and above those things presently mandated,
on the grounds of soaring presently having insufficient safety. That's not
meant to suggest I completely agree with the level of federal mandation
presently existing (I am not an an instructor nor have I ever played one on
TV), just that "the safety card" over-enthusiastically applied can squash just
about any human activity unto death. (How ironic.) A life reality is there's
no practical way to avoid having to "self-certify" by innumerable daily
decisions/judgements/practices, if we're to remain alive so we can continue to
enjoy what life has to offer. Soaring isn't immune from the
"self-certification need."

Sensible ways for Joe Soaring Pilot to "post-licensing self-certify" would
seem to be much more widely known in general than are (f'r'example) certain
areas of need (e.g. how to enhance aileron power at low speeds). But that'd be
another thread...!

> Thanks for the explanation.
You're welcome. This aspect of soaring eventually became a subtlety left for
Joe Soaring Pilot to discover, contemplatitively explore, and learn how to (if
deemed desirable) mitigate "on his own"...and evidently, still is. An easy way
to "avoid the need" for this particular bit of self-teaching is to avoid
flying those higher-aspect ratio glass gliders none of us would ever willingly
give up! Interested readers will find references to the technique beginning to
appear in "Soaring" mag way back in the 1980s.

Bob W.

---
This email has been checked for viruses by AVG.
http://www.avg.com

[email protected]

June 18th 17, 01:54 AM

On Saturday, June 17, 2017 at 4:25:51 PM UTC-4, Echo wrote:
> My only point against teaching it is the complexity it adds to a launch, when there's already a lot going on and plenty to be aware of. I can see it needs to be muscle memory. Thanks for the explanation.

I don't know of anyone who teaches it. I watched other pilots do it and spoke with them, then tried it myself. It works on my ASW 24.

BTW, I cycle the dive brakes open and closed (without locking them) as the slack comes out of the rope to let the wing runner know I haven't simply forgotten to lock them. Once I have aileron authority, I close and lock them and then focus on lifting off smoothly. Yes, it's one more motion. But I flew a flapped ship for a long time and lowering the flaps to lift off is a little bit analogous, although the lever moves in the opposite direction.

Gary, it's possible you didn't find it necessary because the Pegasus wing may have had a lower angle of incidence than some other Standard Class gliders. I seem to recall reading or hearing that although I can't find any references.

Chip Bearden
"JB"

John Cochrane[_3_]

June 18th 17, 01:58 AM

Many a tow pilot has wondered, "why are they all whining about 60 knot tows, when that's well above their stall speed, even ballasted?" The answer is that gliders following the towplane are in the downwash of the wing -- not the propwash, the downwash -- but the wingtips are not. So, the wingtips are operating at a larger angle of attack than the main wings. They will now stall first.
Even if the wingtip doesn't stall, the aileron does -- you get the aileron response of ragged edge of stall though the main wing is flying. That's why gliders get wallowy and hard to control on tow behind slow towplanes. This has caused crashes. That's also why it's especially a problem when the towplane takes off, gets up to speed, and then heads for the sky, losing speed, as quite a few tow pilots seem to do. Now the glider is slow, stuck in ground effect, well below the towplane, and deep in the downwash. Yes, airspeed indicators are off, but it's not that hard to be aware of the issue, and ask the first few pilots for a calibration. I think the larger problem is we all get used to towing dry, and the higher speeds just don't feel right.. It's a worse problem for standard class, since they're stall speed challenged to start with and many flaps typically allow a little more twist.

10.6.2.9 ...Towplanes will tow at 80 miles per hour (unless otherwise requested) in a pre- selected pattern to an altitude of 2000 feet AGL (or as specified by the CD).

June 18th 17, 02:16 AM

Thanks, Chip for a great post.
We all find ourselves exceeding personal rules at times, and sweep them under the rug as "I got away with it."
Jim

[email protected]

June 18th 17, 02:32 AM

What John said, even though he had to go and mention "whining" again. :)

For more discussion (any takers?), see "Glider Handling on Tow" on RAS a few years ago: https://groups.google.com/forum/#!searchin/rec.aviation.soaring/%22glider$20handling$20on$20tow%22/rec.aviation.soaring/rxCTVDJnKVc/Qn6gkHnP7EgJ

My number is 60 kts. dry and 70 kts. fully ballasted in a Standard Class glider. Below those numbers, I am VERY uncomfortable and less maneuverable. So add 5 kts. to allow for tow pilots who ease back on the stick after they've climbed up a few hundred feet.

Flapped 15M gliders have a bit more margin. Big ships seem to have still more but I can't speak from experience.

Chip Bearden
"JB"

Echo

June 18th 17, 03:52 AM

Congrats on your 8 years of CFI work. I hope that wasn't meant to start a measuring contest, because it won't end well.

And everyone can always use a little more training. Anyone who thinks they don't need practice is the most dangerous one on the field.

Echo

June 18th 17, 03:57 AM

I must admit the downwash discussion is one I'm not fluent on. I've been around a while, but it's certainly an interesting concept I don't know much about. Makes you wonder how high a position you'd have to be for it not to matter...especially when you consider actual climb gradient, compared to AoA and angular fluid dynamics from the tug wing back to a glider 200' back. I haven't seen it in any book, but the books have been updated a few times and it doesn't mean it doesn't exist.

Echo

June 18th 17, 04:00 AM

That's true....seems ballasted standard class birds have gotta be the highest speed required on tow group. Can't speak much to open class. Not a lot of that on the east coast.

Martin Gregorie[_5_]

June 18th 17, 10:45 AM

On Sat, 17 Jun 2017 19:57:22 -0700, Echo wrote:

> I must admit the downwash discussion is one I'm not fluent on. I've been
> around a while, but it's certainly an interesting concept I don't know
> much about. Makes you wonder how high a position you'd have to be for it
> not to matter...especially when you consider actual climb gradient,
> compared to AoA and angular fluid dynamics from the tug wing back to a
> glider 200' back. I haven't seen it in any book, but the books have been
> updated a few times and it doesn't mean it doesn't exist.

Its even a bit worse than has been described: your outer wings and
ailerons are in the tow plane's wingtip vortex, which adds a still
further to the AOA difference due to the upward flaw in that part of the
vortex.

Low tow may be a better answer simply because it puts the whole glider
below the tugs downwash and tip vortices. It certainly feels smoother,
but doesn't sort out takeoff and initial climbout problems.

Side comment: the issue of wingtips extending beyond the tug's wing
downwash in pretty much unique to our sailplanes: all of the Allied troop
carrying gliders during WW2 had lower spans than their tugs (a Waco CG4
is smaller than a C47 - look it up if you don't believe me). The only
exceptions were the British Hamilcar (about 6 feet bigger span than the
Halifax tow plane and one or two of the German and Russian troop carriers
when towed by single engine aircraft and, of, course the Me 321 Gigant.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Echo

June 18th 17, 02:50 PM

Wow that's interesting stuff. I once went to a WW2 glider museum in Iron Mountain Michigan, but it was more about the manufacturing and stories and less about the design and flight characteristics. The only time I've ever noticed any kind of wash from a towplane is on pavement behind a CAP 182. 100' into the takeoff roll, the right wing always drops. It's a briefing item when we fly there. Spiraling slipstream of a tri gear vs taildragger.

It's a shame we can't put a glider and towplane in a wind tunnel together....or at least some smoke/fluid testing released from the towplane wingtips. So much of aerodynamic "fact" isn't really known, but more speculated and generally accepted. Would be a pretty neat study to actually watch said downwash. I still have never noticed it in flight; It was explained differently to me many years ago, and it has always seemed to prove to be passing below me. If the glider keeps the towplane referenced on the horizon from high tow position, they're essentially level horizontal with each other. That means that the towplane is not dragging the glider through it's path, but rather the two are climbing together, a level horizontal plane going up. (Most gliders' drag in lbs at a tow speed is probably only 50ish pounds...so the tension on the rope wouldn't be much more in order to yield a climb at constant speed. Similar to the discussion on excess power required for climbs in the book Aerodynamics for Naval Aviators). If applying that theory of the horizontal plane climbing evenly, and towing at say 60kts and 500ft/min (for simple math), that's a climb gradient of 500ft/nm, or 5 degrees. So the relative wind is essentially from 5 degrees above the horizon, and downwash results in 5 degrees off below to the rear, or more depending on angle of incidence, etc. That, at 200, back, puts the theoretical downwash line a little over 15 feet below the level horizontal plane that the glider exists in with the towplane. So clearly in that theory, a weak towplane and a heavy glider has many issues beyond clearing the trees, but a strong towplane makes everything less of a factor.

Again that's just a theory, just like the perceived downwash one. My only point here is to say that all this stuff is theory, something from voodoo black magic aerodynamics. It would be truly interesting to hook up some smoke canisters across the wing of the tug and see where it all goes. Same with the tips.

I would love to hear the perspective of military guys here who have done many hours of aerial refueling...what they think about the presence of downwash and how much it affected their aircraft when sitting behind a tanker (with a much higher wing loading).

Jordan

Dan Marotta

June 18th 17, 05:04 PM

This is a great discussion!

Before I retired from towing, my technique was to level off in ground
effect until reaching full towing speed (and note that the glider's
ground effect is deeper than the tug's due to the difference in span)
and then begin a gentle climb at a pitch rate which would preclude a
reduction in airspeed. Some glider pilots like to be towed at 75 KIAS
when fully loaded.

On 6/17/2017 7:32 PM, wrote:
> What John said, even though he had to go and mention "whining" again. :)
>
> For more discussion (any takers?), see "Glider Handling on Tow" on RAS a few years ago: https://groups.google.com/forum/#!searchin/rec.aviation.soaring/%22glider$20handling$20on$20tow%22/rec.aviation.soaring/rxCTVDJnKVc/Qn6gkHnP7EgJ
>
> My number is 60 kts. dry and 70 kts. fully ballasted in a Standard Class glider. Below those numbers, I am VERY uncomfortable and less maneuverable. So add 5 kts. to allow for tow pilots who ease back on the stick after they've climbed up a few hundred feet.
>
> Flapped 15M gliders have a bit more margin. Big ships seem to have still more but I can't speak from experience.
>
> Chip Bearden
> "JB"

--
Dan, 5J

June 18th 17, 05:10 PM

On Friday, June 16, 2017 at 4:55:55 PM UTC-7, wrote:
> I have a secret.
>
> Well, like secrets in a Congressional Intelligence subcommittee, this one is probably known by several hundred people. But I haven’t written about it. Until now.
>
> But first, the lead in. A few days ago on the last day at the Cordele nationals, I dropped a wing on takeoff. The ballast tanks were half full so although the tip didn’t go down hard, the water sloshed in that direction and the wing stayed down. My ASW 24 started to swing off to the right. I wasted no time in pulling the tow release. The glider continued to swing and I braked as I rolled off the asphalt runway into the grass and stopped..
>
> No big deal. I’ve had a rule for many years that if the wing goes down early with ballast, I release. It's almost impossible to get the tip up again (more later). I’ve done it twice before--both times on grass--and it’s slightly embarrassing but uneventful except for blocking the launch. This time I actually rolled out of the way. Not much more than five minutes later, I had been retrieved with a golf cart, put back on the launch line, and was away without ever having to climb out of the cockpit.

[email protected]

June 18th 17, 07:00 PM

The tailwind in Cordele was minimal; a few knots. At Nephi last year, IIRC it was more substantial: perhaps 10 kts. We gridded that way because the wind was forecast to (and did) become more of a headwind early in the launch.

The few launches before mine were uneventful. As is true with most things at contests, no one forces you to do anything: launch, start, fly the task, final glide low over unlandable terrain, whatever. It's always pilot's choice. Sometimes we put pressure on ourselves to exhibit the "right stuff" and carry on like everyone else.

Nephi has a single hard-surface runway so the alternative was gridding at the other end, then elephant walking the entire length after the early gliders had launched and the wind shifted. With three classes on the grid--including the Open Class birds at the back--that would have complicated matters even more. The launch operation had been slower than desired during the practice period so the last thing anyone wanted was a delay. I believe this was the day that someone on the radio reported a dust devil in the vicinity of the departure corridor just off the end of the runway. After a minute's reflection, the order came down, "Continue the launch!" Already airborne, I heard the next couple of pilots radio their alarm and unhappiness after they hit the turbulence. There was probably a bit too much "full speed ahead" on all our parts.

I've carried on way too long already but I'll add two more points that help explain where I went wrong. Back in 1982 at the Elmira 15M Nationals, I was #1 to take off. The wx forecast was good but there was a significant quartering tailwind. No way to launch in the opposite direction. The decision whether to cancel the day would be based on how my launch went. Pressure! I consulted more experienced pilots, including Elmira's Roy McMaster. I briefed my sister, Diane, how to run the wing. With partial ballast and a tailskid on my LS-3, I knew keeping the wings level and the fuselage aligned were both critical.

The initial roll went fine: wings level and straight. But as we rolled off the end of the hard surface onto the grass, neither I nor the tow plane was airborne. The grass eventually slopes down slightly at Harris Hill before falling off more sharply. Once we broke ground, all I had to do if things weren't progressing was coast out into the valley where I could glide to the big county airport. I was told we went out of sight still on the ground and disappeared. Many seconds later, when we reappeared far out in the valley, level with the top of the Hill and climbing, a big cheer went up! Most flew that day but one pilot's crew didn't seem to understand the concept of running with the wingtip as long as possible and he gave up after three aborted attempts.

I suspect I've been overconfident about non-standard take offs ever since....until last summer at Nephi.

The second point involved an aero retrieve at Region 4 the year before Nephi. The owner of the grass strip, a pilot himself, towed my ASW 24 back to the end of the runway and I briefed him on how to run the wing. My biggest caution: "Don't hold the wingtip back; let the trailing edge just fly out of your hand." Of course, he did the exact opposite and steered me right toward the fence. But with M-ASA's powerful Pawnee ahead, the glider responded almost instantly to full opposite rudder and I straightened out just before reaching for the release.

So at Nephi, with the confidence that I had dealt with similar situations in the past and seeing other guys take off just fine, I accepted the launch. And when the nose was pulled off track almost immediately, my first reaction was "I can do this (just like I did last year)." The difference was a much higher density altitude, full ballast, and a significant tailwind.

I did just about everything wrong, from the pre-flight planning all the way through the takeoff itself. I'm very fortunate I didn't ground loop when I rolled off the runway and do some real damage.

Now for real question no one has asked: would I accept the Nephi launch again? Yes, with my own wing runner and a commitment to pull the release as soon as anything went wrong. I was the only pilot in the "downwind" group who had a serious problem that day and I could have avoided it by executing my long-standing contingency plan.

As to why no one radioed about the landing light, I believe everyone thought I must have known and elected to continue anyway.

Chip Bearden
"JB"

Martin Gregorie[_5_]

June 18th 17, 08:13 PM

On Sun, 18 Jun 2017 06:50:31 -0700, Echo wrote:

> Wow that's interesting stuff. I once went to a WW2 glider museum in
> Iron Mountain Michigan, but it was more about the manufacturing and
> stories and less about the design and flight characteristics. The only
> time I've ever noticed any kind of wash from a towplane is on pavement
> behind a CAP 182. 100' into the takeoff roll, the right wing always
> drops. It's a briefing item when we fly there. Spiraling slipstream of a
> tri gear vs taildragger.
>
> It's a shame we can't put a glider and towplane in a wind tunnel
> together...or at least some smoke/fluid testing released from the
> towplane wingtips.
>
There seems to have very little research into glider towing, not even in
the Akafliegs, which did surprise me.

Take a look at this:
Wake Turbulence Hazard Analysis For A General Aviation Accident, DLR
2014, DocumentID 340177

You'll need to run a search as I don't have the URL to hand. Its a report
on a crash when a Robin GR400 took off too close behind an Antonov AN-2,
so not directly about glider towing, but there is some good info and
numbers about tip vortexes.

A glider on a 200 ft rope is close enough to the tug to be flying in its
downwash field if it is in the normal tow position, with the glider just
above the turbulent prop wake, which is angled down behind the tug's
flight path at about 1/3 of its AOA. and you can get some idea of the
downwash depth at the glider's distance if you extrapolate from
assumption that the downwash thickness is about half the wing chord at
4-5 chords behind the wing. NOTE this the tug's wing-generated downwash
and has nothing to do with the turbulent prop wake: I don't know how that
is positioned in relation to the wing downwash, how far back it extends
or what its 3D shape might be.

> So much of aerodynamic "fact" isn't really known,
> but more speculated and generally accepted. Would be a pretty neat
> study to actually watch said downwash.
>
It seems to me that this topic could be the basis of a really nice PhD
thesis for an aerodynamicist.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[email protected]

June 19th 17, 12:55 AM

IIRC Gliding International magazine had something on towplane/glider interference sometime in the last year.

George Haeh

June 19th 17, 04:58 AM

My limited exposure to aerodynamics textbooks leaves me with the
impression that airflow behind the vehicle is neglected.

When heavy jets came out, there was a spate of light aircraft crashes in
wake
encounters, followed by NASA research and guidance on avoiding.

I have not come across any formulae for air behavior behind aircraft. There

are simply general statements that the air will be descending and vortices

will trail the wing tips.

Perhaps a good analogy for being behind a towplane is that it has
similarities
for approaching a ridge from downwind - a bad place for being slow.

bumper[_4_]

June 19th 17, 08:40 AM

At a flyi that included various flying and landing contests, I was helping with the release of helium balloons for the pilots to try and pop. Harder than some would imagine, as there were a lot more misses than hits (except for ace pilots such as myself). Several of the missed balloons got sucked into the wing tip vortices where they almost stayed in place while rotating at least several hundred rpm. This experience, and other explanations of tip vortices, led me to believe they were of small diameter directly behind the aircraft and expanded in diameter the further back they got while sinking at several hundred feet per minute.

This picture is from "wiki".
https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Airplane_vortex_edit.jpg/220px-Airplane_vortex_edit.jpg

I was on a photoshoot for a backcountry flying video with my Husky at Nevada's Black Rock Desert. Near the north end of the desert there are a couple of small playas that are protected from the wind, surrounded by small mountains. The playa surface had fine alkali dust that readily showed the air disturbance behind the Husky, which normally takes off full flaps. As soon as the plane started its take off roll, each tip vortice looked to be about 20 feet in diameter, sucking the fine dust up from the ground and rolling it up and over onto the wing reaching almost to the fuselage - it looked impressive.

The Husky has a perhaps undeserved* reputation for "Moose Stalls". So named as the aircraft is typically circling low over game counting animal populations or doing photograph. It is thought the aircraft, while circling tightly, dirty or "slowed up" with flaps extended, flies into its own wake causing a low altitude stall and loss of control. I have flown into my own wake doing this, though at higher altitude with room to recover - it's an eye opener.

*Undeserved, not because it doesn't happen with the Husky, but rather that the Husky has been used by many state Fish and Games for animal surveys, predator control etc. - lots of exposure. There have been Super Cub crashes under similar circumstances.

Martin Gregorie[_5_]

June 19th 17, 01:01 PM

On Mon, 19 Jun 2017 03:58:42 +0000, George Haeh wrote:

> My limited exposure to aerodynamics textbooks leaves me with the
> impression that airflow behind the vehicle is neglected.
>
> When heavy jets came out, there was a spate of light aircraft crashes in
> wake encounters, followed by NASA research and guidance on avoiding.
>
> I have not come across any formulae for air behavior behind aircraft.
> There
>
FWIW the angles and wake thicknesses I quoted work well for free flight
model design, where we know from experience that a model with its
tailplane in the wing wake is not stable in pitch. I've used these values
when designing an F1A with its wing on a low pylon to check that the
tailplane would outside the wing wake. Drawing the diagram said the
tailplane should be in clean air above the wing wake. The model's in-
flight behaviour shows that was a good prediction.

--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Tim Newport-Peace[_4_]

June 19th 17, 02:45 PM

http://cdn.shopify.com/s/files/1/0118/6842/files/Movement_of_jets.pdf?151
Page 2 "Wake turbulence"

At 07:40 19 June 2017, bumper wrote:
>At a flyi that included various flying and landing contests, I was
helping
>=
>with the release of helium balloons for the pilots to try and pop. Harder
>t=
>han some would imagine, as there were a lot more misses than hits (except
>f=
>or ace pilots such as myself). Several of the missed balloons got sucked
>in=
>to the wing tip vortices where they almost stayed in place while rotating
>a=
>t least several hundred rpm. This experience, and other explanations of
>tip=
> vortices, led me to believe they were of small diameter directly behind
>th=
>e aircraft and expanded in diameter the further back they got while
>sinking=
> at several hundred feet per minute.
>
>This picture is from "wiki".
>https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Airplane_vortex_e=
>dit.jpg/220px-Airplane_vortex_edit.jpg
>
>I was on a photoshoot for a backcountry flying video with my Husky at
>Nevad=
>a's Black Rock Desert. Near the north end of the desert there are a
couple
>=
>of small playas that are protected from the wind, surrounded by small
>mount=
>ains. The playa surface had fine alkali dust that readily showed the air
>di=
>sturbance behind the Husky, which normally takes off full flaps. As soon
>as=
> the plane started its take off roll, each tip vortice looked to be about
>2=
>0 feet in diameter, sucking the fine dust up from the ground and rolling
>it=
> up and over onto the wing reaching almost to the fuselage - it looked
>impr=
>essive.
>
>The Husky has a perhaps undeserved* reputation for "Moose Stalls". So
>named=
> as the aircraft is typically circling low over game counting animal
>popula=
>tions or doing photograph. It is thought the aircraft, while circling
>tight=
>ly, dirty or "slowed up" with flaps extended, flies into its own wake
>causi=
>ng a low altitude stall and loss of control. I have flown into my own
wake
>=
>doing this, though at higher altitude with room to recover - it's an eye
>op=
>ener.
>
>*Undeserved, not because it doesn't happen with the Husky, but rather
that
>=
>the Husky has been used by many state Fish and Games for animal surveys,
>pr=
>edator control etc. - lots of exposure. There have been Super Cub crashes
>u=
>nder similar circumstances.
>

[email protected]

June 19th 17, 05:16 PM

I feel like retitling this from TTTO (Tale of Two Takeoffs) to SSST (Survival Strategies for Slow Tows). :)

Does this mean that if we're trapped on a slow tow, we should drop down into low tow position...or move up even higher than normal (if that's possible by then)...or move out to the side--all to escape the downwash?

Chip Bearden
"JB"

Tango Eight

June 19th 17, 07:13 PM

On Monday, June 19, 2017 at 12:16:35 PM UTC-4, wrote:
> I feel like retitling this from TTTO (Tale of Two Takeoffs) to SSST (Survival Strategies for Slow Tows). :)
>
> Does this mean that if we're trapped on a slow tow, we should drop down into low tow position...or move up even higher than normal (if that's possible by then)...or move out to the side--all to escape the downwash?
>
> Chip Bearden
> "JB"

Speaking as a guy who's been there: you ain't gonna have the choice. You are going to be heading for deep low tow whether you like it or not. Whether you fall off depends on what your tow pilot does next.

Evan Ludeman / T8

Steve Koerner

June 19th 17, 07:19 PM

Responding to the slow tow matter...

I've written on this subject here on RAS before as it's one of my pet pive safety concerns. I've had a few seriously slow tows with water. My experience is that you will drop into low tow whether you want to or not - there's no choice to be had. In the extreme case, expect to be hanging lower than "low tow" at a high pitch angle slamming alierons to the stops. When this ocurrs at low altitude, there's no possibility of recovering should you disconnect from the rope.

I now keep printed instructions for towing with water ballast in the side compartment of my glider. If I don't have the chance to talk to the tow pilot immediately before the tow, then I will have the ground crew deliver written instructions to the tuggie as I'm being hooked up. Written instructions are less likely than a radio call to be confused, forgotten or misunderstood.

Here's a pdf of my written instruction sheet:
https://drive.google.com/file/d/0B_X0Wzn5Wi43WGtXTE9lTms4d0E/view?usp=drivesdk

Steve Koerner

June 19th 17, 07:25 PM

Looks like Evan and I were typing at the same time and have had the same experience.

Tango Eight

June 19th 17, 07:52 PM

On Monday, June 19, 2017 at 2:25:49 PM UTC-4, Steve Koerner wrote:
> Looks like Evan and I were typing at the same time and have had the same experience.

Yep. Loss of roll control in my case too.

-Evan

[email protected]

June 19th 17, 08:02 PM

It's not like I haven't been there, guys. The ballasted occasions are almost all at contests and the tow pilots have generally responded to my agonized pleas for more speed.

The scariest one was actually dry, though, at a local club. It's the closest I've come to losing roll control or having to pull the release. And, yes, I was in near-low-tow position.

I was just wondering if settling even lower might help get me out of the downwash, at least when using a longish rope. I've towed at Hank's Middletown operation, which uses low tow exclusively, and if you're not used to it, it looks very strange (although it works very well). I don't think I've been down that low in my slow-tow adventures.

Chip Bearden
"JB"

Don Johnstone[_4_]

June 19th 17, 11:26 PM

At 19:02 19 June 2017, wrote:
>It's not like I haven't been there, guys. The ballasted occasions
are
>almos=
>t all at contests and the tow pilots have generally responded to my
>agonize=
>d pleas for more speed.
>
>The scariest one was actually dry, though, at a local club. It's the
>closes=
>t I've come to losing roll control or having to pull the release. And,
>yes,=
> I was in near-low-tow position.=20
>
>I was just wondering if settling even lower might help get me out
of the
>do=
>wnwash, at least when using a longish rope. I've towed at Hank's
>Middletown=
> operation, which uses low tow exclusively, and if you're not used
to it,
>i=
>t looks very strange (although it works very well). I don't think
I've
>been=
> down that low in my slow-tow adventures.
>
>Chip Bearden
>"JB"

I have been there, in my case I was in a K21 2 up behind a Rotax
Falke. (Motor glider with big engine). I was definitely in low tow and
had no way of getting out of it. The problem as I see it is that if
you sink low enough you could make it extremely difficult for the
tug to lower the nose to give you more speed, in which case he will
probably give you the rope, not a situation I would care to be in.
The radio call in my case was heeded.
Someone once told be that in Australia they all use low tow as the
norm, even releasing in low tow which I admit I never have. I have
always used low tow on cross country tows as it is a lot more
stable. I have always transitioned to high tow for release.

Ben Coleman

June 20th 17, 12:44 AM

On Tuesday, 20 June 2017 08:30:05 UTC+10, Don Johnstone wrote:

>
> I have been there, in my case I was in a K21 2 up behind a Rotax
> Falke. (Motor glider with big engine). I was definitely in low tow and
> had no way of getting out of it. The problem as I see it is that if
> you sink low enough you could make it extremely difficult for the
> tug to lower the nose to give you more speed, in which case he will
> probably give you the rope, not a situation I would care to be in.
> The radio call in my case was heeded.
> Someone once told be that in Australia they all use low tow as the
> norm, even releasing in low tow which I admit I never have. I have
> always used low tow on cross country tows as it is a lot more
> stable. I have always transitioned to high tow for release.

Confirmed, low tow is the norm here - just below the prop wash. The only time I have been in high tow is boxing the slipstream. One of our old hands used to transition to high tow for release (it was speculated that it was to get a few free feet of altitude) but it wasn't appreciated by the tuggies.

I have had one "memorable" towing speed incident. In my first ballasted comp. flying a Jantar Standard, the tow plane climbed out while I was still on the ground. I yanked the glider into the air and it took a few moments to get my wits about me to call for more speed. It was not something I had expected or prepared for and I should have released. It still gets my nerves jangling when I recall it.

I am doubly careful to make sure the tow pilot knows I am ballasted now, thanks goodness I have not had such an experience since (although I have had to ask for a few more knots now and then).

Cheers Ben

Charlie M. (UH & 002 owner/pilot)

June 20th 17, 02:17 AM

From our testing, you "almost" can't get too low on the towplane, most still have elevator authority (for lowering the nose) when you are really low unlike getting too high and you dive him in.

Don Johnstone[_4_]

June 20th 17, 06:48 AM

At 01:17 20 June 2017, Charlie M. UH & 002 owner/pilot wrote:
>From our testing, you "almost" can't get too low on the towplane,
most
>still have elevator authority (for lowering the nose) when you are
really
>low unlike getting too high and you dive him in.
>
Perhaps we can all learn from the boys in Oz. From the last two posts
tug upsets should be almost unknown in Australia.
Is there a case for making low tow the standard towing position in the
rest of the world?
Just from the lessening of the chance of a tug upset it seems that low
tow is the safest option.

[email protected]

June 20th 17, 11:25 AM

Or moving off center to one side ;) Towpilots can skip leg day. Wonder if there is an ingestion, rather than simple interference, of the towplane wake at the glider wingtips similar to helicopter settling with power?
On Tuesday, June 20, 2017 at 2:00:06 AM UTC-4, Don Johnstone wrote:
> At 01:17 20 June 2017, Charlie M. UH & 002 owner/pilot wrote:
> >From our testing, you "almost" can't get too low on the towplane,
> most
> >still have elevator authority (for lowering the nose) when you are
> really
> >low unlike getting too high and you dive him in.
> >
> Perhaps we can all learn from the boys in Oz. From the last two posts
> tug upsets should be almost unknown in Australia.
> Is there a case for making low tow the standard towing position in the
> rest of the world?
> Just from the lessening of the chance of a tug upset it seems that low
> tow is the safest option.

Ron Gleason

June 21st 17, 03:27 PM

Sorry for the delay but am hiking in Germany with limited time and Internet access. My comment about whining pertained to RAS Posts not about speaking up at contests. I cannot speak for others but the contests I have assisted with in thee ground we review everything you mention and we strive no wing drops and appropriate tow speeds.

Of the 700 or so tows at Nephi last year during the Nats I recall 9 wing drops, I do not have m,y notes in front of me. I saw them all, including the one that started this thread. No one common denominator in these incidents. Can we them all? I hope so but human nature is a tough nut to crack

For tow speeds we review with the chief tow pilot, all pilots at the beginning and when we hear for speed calls. Again no excuses but many factors attribute to this situation. Some calls for speed are erroneous when items released such as waffle balls are used to protect rope end and the glider ASI tube is in the nose with the tow hook! I have heard pilots calling for more speed when the tow plane was already doing 75+. We remind pilots about this situation but it still happens every contest I have been involved with.

Getting all pieces together for a contest is a delicate dance with many partners. I do not know any folks organizing contests that does not put safety first. So yes speak up if necessary and better yet lets you and every other contest pilot on t he ground assisting and contributing to the solution at once a year.

One other note concerning tow speeds, it is going to get harder going forward. The latest high wing loading racing gliders are requiring 85 knots at a minimum, according to the manufacturer. Many tow planes while able to dro the speed do not climb as well at those speeds. Sol faster tows may. Mean lower tows which could mean higher tow fees.

Ron Gleason