Winches - Are They Plane Killers?

[screamin' eagle]

After two active years of flying slope, I've gone back to the TD Field and the club where I first learned to fly RC almost 20 years ago. Back then, I had a Gentle Lady and flew it off the high-start. Good times.

The only suitable plane in my hangar right now for thermal hunting is a molded 3.2m Stratos SL. MH32 foil, 75 oz all up. With help, I took her up on the winch last week and I must admit it was a fairly scary experience.

The Stratos used to belong to Joe Wurts, and is still set up exactly like he had it. Needless to say, the tow hook is behind the CG by at least 1 cm and the trip up the winch was quite an adventure. The plane popped off early and although it was never really in danger, I got the feeling that the potential for disaster is quite real.

In slope flying, the most dangerous maneuver to an airframe is Dynamic Soaring. I've done a little, and gotten into the low triple digits in speeds.

To me, launching off the winch seems much more dangerous, particularly because the plane is physically attached to the winch via the tow hook. It seems that I should get a cheaper plane to practice winch launches before risking my Stratos.

I also constantly hear stories of peoples planes getting pulverized in winch accidents.

How dangerous is a winch launch, really? My instructor gave me pointers on what to do in case of a stall, etc., but I'm kind of freaked out about trying it again. What planes would make good winch trainers? It seems most of the built-up ARFs are unsuitable.

[GLIDERGIDER]

I guess I need to move my hook back behind the CG like yours.

Screaming-eagle:
Really, my hook in just in front of the CG, not behind. That might be all you need to do. Move the hook forward. Winching is exciting and it does require a bit of skill, particularly if you the flier is doing the entire job of throwing, tapping the motor foot switch and flying the airplane. The amount of tension on the string before launch is another item to be learned with winching.

If you were in my group, somebody would have offered to help you, by throwing and tapping the winch switch. That gives the pilot instant control of the airplane during launch.

We've had plenty of pop-offs in my flying circles, but its usually due to taking too steep of an accent. Moving the hook forward will solve that problem.

I know Joe Wurts is a renowned pilot, and he's also an expert pushing the envelope in all aspects of flying. That doesn't sound like you right now.

Good luck.

[screamin' eagle]

Hehe, I'm definitely no Joe Wurts. I am trying to find a way to move my tow hook forward. Trouble is that the inside of the fuse has two ballast tubes (that I use when I fly the plane on the slope) and therefore there is no access. It sounds like the winch launch will be a lot safer that way.

[rdwoebke]

Back then, I had a Gentle Lady and flew it off the high-start. Good times.

The only suitable plane in my hangar right now for thermal hunting is a molded 3.2m Stratos SL.

To me, launching off the winch seems much more dangerous, particularly because the plane is physically attached to the winch via the tow hook. It seems that I should get a cheaper plane to practice winch launches before risking my Stratos.


I winch launched my old Getle Lady all the time. You have to tap the pedal, not gas it.

I don't think it is that dangerous. And it seems planes are getting stronger. A few years ago it seemed every contest I was at had at least one wing failure on launch, but that is not the case any longer.

I don't get to use a winch very often, so they kind of make me nervous too.

Ryan

[will_newton]

I've seen planes that are too delicate to winch take a winch start with an experienced winch operator with no problem.

I've seen planes designed for full pedal to the medal winch starts destroy themselves in under a second with an experienced winch operator and pilot.

ALL factors must be taken into consideration. Pilot experience, winch capacity, plane design, winching experience, and weather conditions.

The best advice I can give is, don't go first! :D

Will

[mnluz]

Not difficult at all.... sold my eraser to one guy that never flew a unlimted class glider.. only dlg and powered planes.
At the end weekend he was doing it by himself.

1-Get somenone to thorw the plane and step on the winch pedal for you. Way easier to learn if you master one step at a time.
2-Get someone to setup the model for you.... if launch mode is all right... you should just whatch your plane climb untill zoom time.
2-Then, take control of the winch pedal.
3- Start launching other peoples plane....and then you will be ok to do it by yorself.

Whiches are only hard to the airframes if you push it too hard. You are in control of the winch and plane setup.
Hand tow ? That is another thing.... too fast... bending, bending and bending. You will break it if you push too hard. Y had to be ahead of time... almost no time for corrections.

With a JW setup, tow hook behind the cg, too much flap deflection.... it is a trip. Move the hook reduce a little deflection till your plane climbs safely.

What can be more scarryng than dsying a molded plane ? :eek: Just a learning curve ahead that can be enjoiyable and fast if you get some outside help and master one part of the lauch of at a time. :p

If you wanna come down to Brazil... we will help you for sure. Just one beer and it is a done deal.

Rgds,
Marlon


Rgds,
Marlon

[BMatthews]

If this model belonged to Wurts at one time then I would suggest that it's strong enough that there is absolutely no need to go light on the pedal.

What IS missing is a very solid throw with a healty follow through. The model need airspeed to be up to snuff before it leaves your hand. And given the high artificial wing loading of the model produced by the line pull this is a lot of speed that is needed.

Ever see pics of Joe throwing his model? He's stretched out like an Olympic class javelin thrower and his feet are about a foot and a half off the ground from the leg assist. THis is an all body maximum throw.

If you can manage to duplicate that sort of power in the throw then it'll launch just fine and straight as an arrow.

The hook behind the CG tells me one or two things. Either you're flying it with a more "stable" CG location than Joe did or this is one of Joe's tricks. If it's one of Joe's tricks then you probably need a touch of down elevator mixed in for the launch to prevent the over rotation of the model during the initial acceleration part of the launch.

This is an aggresive model design that was set up in an aggresive manner. I suspect and it just requires commitment and aggresive techniques to launch it safely and comfortably.

Best of luck with it. When it's flying properly I suspect it'll be a wonderous performer.

[Tuomo]

Like this :)

I launch mostly without tapping. Just step on pedal and have fun! Modern F3J planes have no problems with winch launches. You will break the line before folding a wing.

BTW Forgot mention: it is important to launch with good tension. Safer and takes you higher.

[screamin' eagle]

The hook behind the CG tells me one or two things. Either you're flying it with a more "stable" CG location than Joe did or this is one of Joe's tricks.


Hook behind the CG is supposed to give higher launches, so I suspect that's what's happening. As far as CG goes, I've got it set up so it's as far aft as it can go before the model becomes unstable (at least on the slope).

Since slope flying typically involved more turbulence, is it common for CG to be further back for TD flying than for slope flying?

[screamin' eagle]

I forgot to mention that I flew the plane on the winch but did not man the pedal/toss. Is it correct that you push pedal until the line is taught, throw the plane, and THEN hit the pedal again? I would imagine if you tried to toss/pedal simultaneously, the plane might get pulled out of your hands and disaster would ensue...

[Tuomo]

Look at the pics. I hold the plane, step on pedal and when the tension gets really high I throw my plane. With a flexible line it takes 1-2 seconds to pull line really tight. It is not that violent.

Biggest problem when flying alone is holding plane wings level with one hand -- it is important to throw it straight although wind might wobble the wings quite a bit.

You fly with mono line?

[screamin' eagle]

The guys at the field said the line was 500 pound test. I'm not sure if it's mono.

[rdwoebke]

The guys at the field said the line was 500 pound test. I'm not sure if it's mono.

Mono looks like plastic fishing line. Monofiliment is what it stands for, aka one strand. It is very stretchy and stores energy in it. JoJo has posted about doing a "zero man tow" where you basically stake the mono into the ground and you just pull back and build up tension and launch. No way you could do that with braided line, I think.

Most US folks on winches use braided line. AKA looks like kite string.

Ryan - who is no expert on braided, mono, or launching in general but has been around the block to see quite a bit of it

[rogerflies]

If you're tossing the plane with your right hand, you should be tapping the pedal with your left foot. Hold the pedal down until the tension feels about right, then start tapping to keep it there as you launch. Once it's on the way up, you can vary the ratio of motor-on to motor-off time to control the tension. Long pauses are bad, since they let the line get slack, and it may come off too soon. You can get an idea of what the tension is by the speed of the plane, and how it responds to control inputs.

You can practice tapping while holding the line to feel the tension without endangering the plane. Don't do it too much, though, or you'll smoke the winch.

Roger

[Tuomo]

There are many types and thicknesses of mono line available. I think it is more easy to launch well with a more flexible/thinner line.

I have allways wondered why you use braided line? What is the point of it? Monofilament is nice to handle and gives superior zooms after release :confused:

[screamin' eagle]

I think ours is braided line.

[becsta]

I _love_ winch launches, because the launch can send my little 2M First (2ch rudder/elev.) into outer space (almost), whereas I just can't get the same height off the histart.

If the plane is trimmed correctly, and you launch with the right tension in the line, and with the wings level, the plane will ride up the line like it's on rails. I have a touch of up elevator preset for the launch, which I take out before going "over the top" for the speed-n-zoom part.

I've only just stopped the habit of pulling up elevator as it leaves the launchers hand, as the plane will rotate by itself. I'll only pull up elevator if the initial glide is flat.

- bec

[Resurgam]

I think BMatthews got it right. If you can't move the hook, try mixing some down trim in launch mode. It'll keep the nose down a bit in the climb.

[BMatthews]

Tuomo's got the idea but he's still not aggresive enough. His feet are far too close together for a good base to both resist the pull and get a good throw of the model. But he does have a nice follow through.

I wrote up a big post a while back but the basics are that you need to stand chest to the line like an archer and hold the model in your fully extended arm back behind you. Feet should be about 3 to 3.5 feet apart for a good stable base to resist the line tension and so that the rear foot can push harder. For a right handed launch the left foot presses the pedal. When the line tension builds to about 60 lbs you HEAVE the model up on about a 45 degree nose up angle whle staying on the pedal. And I mean HEAVE! It's an F3B model turned slope racer and now it's back to it's roots. The wing will take it if it's not damaged internally from some slope misshap.

It takes some chutzpah to be able to detach yourself from the line pull and properly throw the model. The usual action is to whimp out and just guide the model as the line pulls it away. You THINK you're throwing it but in reality you're arm isn't catching up to the line induced speed. But that path is the road to eventual disaster. Done right the model is flying happily right from the modment your grip is released and the happy result is a dead straight climb.

All those hiccups and other odd things at launch are simply the model leaving in a stalled or near stalled condition.

Sorry if I'm tending to go on but I've seen far too many perfectly good models reduced to rubbly by bad launches. And it's just so preventable.

[GLIDERGIDER]

About a month ago I put this video together for grins and giggles. It was my first thermal session of the year. I'd been flying lots of slope throughout the winter. Anyway, there are two launches and both seem pretty straight and true.

As a bonus, there is some slow motion of the release during both winch launches.

http://www.youtube.com/watch?v=9kbpC33DNxU

[wakumann]

Dominic

pretty sure that JW used start settings on the Stratos to max height.

Some guys use 3 different flap (plus aileron mix) settings during one launch, over a 3-point switch often the servos are time delayed to have smoother transition of the phases.

At least most European TD use this feature (one reason they mostly only use the high end Tx's)

Also the mono line stretches 30+%, this helps to make the launch higher and easier.

Cheers
Thomas

It you not using a 4 HP winch or make major mistakes you can't get a Stratos destroyed on the line, only if it's not structurale sound maybe from some previous fast landings.

Anyway not often that the hook is for fare back, but I quit flying TD long ago so do what I know.

[GLIDERGIDER]

Thomas,
I use two flap settings. (sometimes)
1. At the point of release, full trailing edge camber. Ride it up to the crest.
2. Take camber off for the zoom.

What would be the third setting?
Dave

[rdwoebke]

About a month ago I put this video together for grins and giggles.

Watching a level 5 launch is a pretty good way to get pointers. Somebody posted a pretty cool website/post here on groups a while back where he worked up from the old standard "arm in an L" launch method (hold behind the wing) towards the arm straight behind body method (with the legs apart) like Bruce alludes to. It was a good read and offered pointers. I'm sure a search on this forum will locate it.

Nice vid. Thanks for posting the link.

Ryan

[wakumann]

Dave,
they do the phase just before the crest with acceleration and the following final climb with 2 different settings.
Also (depends on condition) some top dogs fly sideways to get the max stretch out of the line.

but I quit flying TD long ago so what do I know

Cheers
Thomas

[screamin' eagle]

Thanks for the tips, guys. After my last adjustments, the tow hook is now dead on the CG. It is impossible to move it, and the CG has gone as far back as it can (at least on the slope).

I thought the first launches went OK. The gent who was helping me was concerned because he thought the plane came off the line early. He instructed me not to use any camber on the launch.

I have a camber setting already programmed into my tx from sloping (for slowing down and thermalling on the slope or in light lift) but it has some down elevator compensation to keep the plane from pitching nose up and then stalling. Can I use this mix on the winch? Or should there be no elevator compensation in the camber mix? The airfoil is MH32, for what it's worth.

[solo6796]

Try a launch with no camber or flaps and the stab pretty neutral. Judge from the rotation and launch angle you get whether to add a little elevator, camber, flap, or any combination to get an efficient, steep launch. Might take a few launches to get a settting that you like...

Just my 2 cents..

AJ

[atjurhs]

Naaaaa, mine's a sweety. She's let me have about ten or eleven planes - I quit counting. I'd definately say she is not a plane killer.

Oh, you said winches, not wenches. I'm sorry, belay my last :D

[davidjensen]

I have only been winch launching for one year so I'm no expert. Dave Beardsley had a full bling camera at 60 acres a few weeks ago and got these 3 of me launching the 3M. This is one of my sucessful attempts. I have had so many bad launches with some great saves and many sideways popoffs. I think I have figured it out. I step on the peddal and wait for the tension and then I pull the plan back and then throw it. It leaves my hand with so much tension on the string the plane goes into a power stall. It always goes to the right. I will learn somehow someway

[drCarter]

Thanks for the tips, guys. After my last adjustments, the tow hook is now dead on the CG. It is impossible to move it, and the CG has gone as far back as it can (at least on the slope).

I thought the first launches went OK. The gent who was helping me was concerned because he thought the plane came off the line early. He instructed me not to use any camber on the launch.

I have a camber setting already programmed into my tx from sloping (for slowing down and thermalling on the slope or in light lift) but it has some down elevator compensation to keep the plane from pitching nose up and then stalling. Can I use this mix on the winch? Or should there be no elevator compensation in the camber mix? The airfoil is MH32, for what it's worth.




I settup alot of planes for other folks. Here is the safest way I have found to do it. I set the cg right at neutral or perhaps just slightly ahead. I set the hook in the exact same spot. I do a hand toss first and set the neutral trim in regular flight mode. While up high, from a winch launch, I switch the model to launch mode, with camber, and set the elevator preset for a nice slow glide. I do not want to see it stall at all. If it stalls here it will stall on the winch and be very dangerous.

After I am comfortable with the launch mode, at altitude, I can then use it in an actual launch. The plane will not stall and travel straight.

If you find the model tying to dart off, from side to side, add a little down elevator to your launch mode.

I do fly with my hook behind the cg and my model is right on the verge of a stall in launch. I will gain a little more height in launch but you really don't need the drama at this point.

Dwain

[screamin' eagle]

Well, I'm headed to the field this morning. I will report back on how it goes. Who knows, if I can get the launches wired, maybe I can start thinking about looking for some lift. :D

[Tuomo]

Tuomo's got the idea but he's still not aggresive enough. His feet are far too close together for a good base to both resist the pull and get a good throw of the model. But he does have a nice follow through.


This discussion is about the pictures attached to posts #8
http://www.rcgroups.com/forums/showpost.php?p=5563680&postcount=8

Yeah you are right. Those were rather lazy "sport-launches". In competition I like to have much more tension before releasing the plane. In quick tows tension seems to be very important, less critical if you make 5-6 sec tow.

(As an apology, it was also rather windy and rainy day - I was contrating more on keeping wings level. Not so easy with a wet and slippery fuselage...)

There are also major differences in the style. i do want to go personal, sorry, but look how David lauches in pictures attached to post #28
http://www.rcgroups.com/forums/showpost.php?p=5563680&postcount=8

I consider my style where I stand sideways much better. When standing sideways, as if you were throwing someting, with you right arm almost straight back, it is actually quite easy to build up good tension before release. Looks effortless but is actually rather effective.

Opinions, please!


Try a launch with no camber or flaps and the stab pretty neutral. Judge from the rotation and launch angle you get whether to add a little elevator, camber, flap, or any combination to get an efficient, steep launch. Might take a few launches to get a settting that you like...


Hmm... I have newer had a plane that launches well without substantial camber. Depending on wind, I use initially about 10-15mm, reduce it to close to neutral at about 1.5-2 sec, and go to slight reflex in zoom (snap flaps mixed).

It is also important to have ailerons (almost) in line with flaps. This give more lift, lift is tension, tension is speed, and in zoom speed is converted to height. alternatively speed allows you to make a short 2-4 sec tow, which is important in F3J. Still learning that :cool:

[screamin' eagle]

Manned the pedal and sticks today, but didn't toss. The plane loves full pedal but the guys at the field were too scared to do it. I took care of that. :D

[LVsoaring]

Screamin', your first post gets to the heart of this issue...."How dangerous is a winch launch, really? " Lots of good posts and info here, but as to the danger of it, simply stated, it's like anything else.... driving a car, flying an airplane, brain surgery, swilling a case of beer.... you have to know what you're doing, get some help learning, and develop your own style that you're comfortable with. I've only been winching for a little over a year, so I'm no expert, but once you find your comfort zone, you'll get good launches, and you won't break wings.... not too often anyway!

Good lift!

Rick

[mlee8249]

Screamin'

You bought a JW plane....couple of things. The hook position is there because that's where JW felt the optimum position was and for him it rotates immediately from there. Now, he can afford to do that for one big reason...he is left handed. So am I. That allows us to place our right hand on the sticks at all times and makes our ability to control the plane faster than someone who throws right handed. So, Joe can throw and make immediate attitude adjustments that you may not be able to make in time because you may be right handed. It is a distinct advantage! By the way, in HLG, both of us can throw left or right handed...and often do.

The safest position to start from is always just ahead of the balance point. I like to start with 1/8 inch in front. I then begin to optimize the launch by moving it back a small bit at a time until the plane begins to be unstable for me at launch and then move it back to the last comfortable position. Every plane is different. Some might remain just ahead of the CG, while others may end up wayyyy back there...like yours.

But getting back to your question, is winch launching safe? Absolutely. It requires time to learn how and the safety aspects of the process, but once you know and learn, it becomes as routine as you doing DS'ing on the backside of the slope. I will give you one piece of advice...When you bring that winch line up to tension, do not just release the plane. THROW that plane like there is no line attached. If the line breaks at that moment of truth, and if you fly long enough it will, the only forward momentum that plane will have is the power of your arm. A good throw will insure you have enough forward speed to glide away safely and not dork the plane.

Mike Lee

[OVSS Boss]

Agree with Mike, JW's settings are aggressive. Here is a pic of me launching to give you a look at what my style looks like.

Marc

[Frank S]

I can't find the original thread this was in, but Mark Drela posted something a while back about launching with an aggressive tow hook position. I found a quote from Mark's original post:


> This is rather far aft hook position which requires
> special action during launch. On my Evo program the
> left slider is an elevator (speed) trim with a small gain.
> For the launch throw I push the slider all the way forward
> which feeds in a slight amount of down-elevator.
> Once the glider rotates and settles down in the climb,
> I pull the slider back to its normal center position
> for maximum load just short of stall. I have 100% Ail.Diff
> and lots of Ail->Rud coupling during launch, so I can
> steer with might right thumb, leaving the left thumb
> free to work the slider.
>
> PS
> I've done some sims of the initial pitch dynamics
> immediately after the throw. There is a very significant
> CL overshoot at the end of the initial nose-up rotation.
> So if you trim the glider for maximum pull during the
> climb and zoom, and throw with this trim, then you are
> guaranteed to stall at the top of the nose-up rotation.
> So for maximum launch performance, it is necessary to add
> some initial nose-down trim to safely get past the
> initial pitch transients after the throw.
>

I seem to remember that Daryl Perkins had an interesting response, but I can't find it anymore. Does anyone else remember this exchange?

[BMatthews]

David, you're suffering from the same lack of throwing speed that started this thread. Take a look at the style in OVSS's pic. He's far more chest to the line with the model behind him and ready to javelin throw the model. You're shots show far more of an over the shoulder style. It's just impossible to get any power into the throw with an over the shoulder style. With the line over the chest side stance you not only get a good arm path but the upper body can then twist during the throw which adds a lot of power to the launch.

I keep coming back to the idea that a good glider launch for these slipper and heavy models needs to look like an Olympic javelin throw but without the runup to the line.

Tuomo, sorry if it seemed like I was coming down on your style. The write up was good but as you say the pictures just didn't follow the writeup.

It's odd. I've gone looking on the 'net for picutures of good launch styles but all I ever seem to see is the usual face down the line and model over the shoulder sort of pictures. Invariably the flyers in these shots all rely on a dead level release to get the model away safely so it can build up speed and then pull up to the climb. It works but it's rather wasteful of tow line length and energy.

I know I've seen shots of Joe Wurts almost exploding off the ground during the launch for one of his F3B models. In that shot his feet were about a foot in the air and his body is streched out fully with the model climbing straight up right from release. Now this is sort of the other extreme since it's rather hard to keep your foot on the winch pedal during such a launch... :D Obviously for these models blipping is not needed.

I also saw a shot of him in the tension buildup phase where he's got his feel spread out like a sumo wrestler to withstand the line pull during the buildup. These shots may have been in a magazine because I sure haven't seen them on the 'net anywhere.

Anyhow, OVSS's style is the best picture of what I've tried to describe so far. It also shows how you hold the Tx and antenna down low and away from the line to avoid any chance of line fouling.

[Tuomo]

It is a mystery to me how the antenna clears line/plane when using large Graupner radios... On the other hand, there is no risk of dropping a European style radio :D

I have seen JW launch in F3B WC, not happy with the tow, come down quickly, catch the plane and take a relaunch :eek: That was some action! For the rest of making a single controlled launch is big enough task. I have no problems flying alone, but in competitions I like to have someone to launch for me.

BTW Extreme towhook positions can be dangerous. I have witnessed a Sharon crash due to tow hook little rear from CG. Many flights had been done safely with setup but this time the launch was little sloppy with some tailwind... That happened quickly!

In F3J it is also very important to have a fast tow. One can sacrifice some height for speed, hence slightly forward towhook position is often prefereable.

[mlee8249]

Hi MArc,

That's the photo that tells it all. Lots of tension on the line, the plane is wings level, the nose is pointed slightly up, and you are ready to give it the THROW! About the only thing that JW does different, (besides throw left handed), is that he really points the nose up to have the plane into the rotation the instant it leaves his hand. That alone is worth 40 feet of additional altitude. But, you better know what you're doing or it's curtains! In the photos before, where the pilot is tossing over his head, you can tell the plane is rotating up after leaving the hand, and I cannot tell you how far back he had his arm cocked back when he started the throw, but it does not appear to be very far back, given the point of where the rotation is beginning, out in front of the pilot. Also, when holding the plane behind the wing like this, you simply cannot give the plane as much throw as you can when holding the plane further up on the nose, as Marc is doing. Don't get me wrong, as this type of throw is more common than not, and if the plane is launching okay, then you're doing fine. My point to my comments is that Marc is showing what makes an excellent throw for winch launch, versus what is the average throw for winch launch. This excellence results in better altitude at the top of the launch, meaning more potential for finding lift with higher altitude. His chances of beating you in a round of thermal competition is better because of this. But, if we are just flying for fun and sport, who cares? Just launch and be happy. I know that when I sport fly, I do all sorts of wierd stuff on launch and I'm really very careless. But when it comes to competition launches, I give it everythig I have to make it perfect, powerful and with a very steep climb angle...just like Marc. Thanks, Marc!

Mike Lee

[OVSS Boss]

No problem Mike, glad to help. Now, the only problem I have is that my right shoulder had surgery and that throw is on hold for a while anyway.

Marc

[allanp]

Is there a corellation between CG and Tow hook position ? Sorta but ,not really. If you think of the plane as a kite on a line with the tow hook being the point where the line attaches to the bridle on the kite you'll see what I mean.
If you have a fixed hook launch attitude will remain the same regardless of CG(don't touch those trims),however as you move the CG around you must change the elevator trims settings to maintain level flight,so if you add nose weight (CG fwd)you'll add up trim to hold the same flight attitude.So effectively you've added up trim to your launch configuration and you must move the hook forward to compensate for the trim change added to your launch settings. If you take out nose weight (moving the CG aft) you add in down trim, now your launch will be flat,so we move the hook back. When you buy/build a new plane if the hook is aft of the planes Cg then you can bet there is nose down trim dialed in and the hook has been moved aft to maintain the desired launch angle of attack.
Allan

[mlee8249]

Hi Marc,

Shoulder surgery, huh? I just had knee surgery to the right leg to replace the ACL, PCL and repair the miniscus...fairly big surgery. But, I did the damage playing softball, not tossing HLG. So, I haven't been doing the big throws either. In fact, I didn't fly the IHLGC in Poway because I can't throw as yet. It's the twisting that will kill me right now, not the actual toss from the arm. So, my winch launches have been fairly sedate. I hope your shoulder is doing better. I think I would rather have my knee problem than your shoulder problem. At least I can still fly and stuff, where with the shoulder, that might make it hard to hold the Tx. Get better and hope to see you in Muncie for the Soaring Masters event.

Sincerely,
Mike

[VE6WEM]

After observing the launches at the F3J WC last time, I throw as shown below. All of the guys and gal getting the highest tows throw like this.

[jrerickson]

BMatthews,

You can still get a fine launch without having to throw as hard as you can. Much of the tension built up in the line depends on the line being used. If Screamin' Eagle is using 500# test (which I doubt, probably more like 300#) there is virtually no stretch in the line. With this line the throw helps but when you are starting out having everything squared up and wings level is just as important. If you throw hard and at an angle off to the side you can do more damage than just by letting the plane go out of your hand with good tension. You say "rather wasteful" but these are optimized terms and for a beginner they just want to get the plane up safely.

Wind direction and speed also come into play. If he has a Stratos he can probably just step on the pedal the whole way up, especially if the wind is under 5 mph. When I'm showing beginners how to launch off the winch I'll throw the plane while they operate the foot pedal. An extreme rear towhook position is going to make the plane rotate instantly and for a beginner this is scary; the plane heading straight up and on the verge of a stall if the speed isn't kept up.

I would say bore a hole through the ballast tube so you can get to the tow hook and move it forward 1/4" till you get used to the feeling of the plane going up the line. I know another thing: The current tow hook position in that plane is perfect, once you get the technique down!

John

It's odd. I've gone looking on the 'net for picutures of good launch styles but all I ever seem to see is the usual face down the line and model over the shoulder sort of pictures. Invariably the flyers in these shots all rely on a dead level release to get the model away safely so it can build up speed and then pull up to the climb. It works but it's rather wasteful of tow line length and energy.

[bobby legue]

When Im teaching winching to the newbees they are instructed to learn the throw first. Keeping the wings and fuse level are the primary initial goals. Secondary is the speed of the tapping. Then Ill throw and let them tap and last thing to do is let them put it all togather. After several launches you just see that can comfortably launch and that is when I suggest that they increase the angle of the launching, usually by showing them the launch and angle. Seems then they start trying different angles, speed, and even some zooming. All this is done from the same plane. As far as stance just let form come after function, let their bodies create the stance necessary to launch as they see fit. Ive taught dozens of people to winch, no world champs but a lot of happy sucsessful pilots flying in contests out there. Yes, some are now much better than me!
Bob

[BMatthews]

John, I agree that a throw isn't neccessary if the flyer lets the model go straight out and level and relies on the towline to build up the speed and rotate the model upwards in a natural way. But using the line tension to accelerate the model means probably 30 to 40 feet at least that won't be there at the top of the launch. So it is fairly costly in terms of launch height. But it is an option.

BUt once the nose is raised even a little upwards with the intent to be on the climb from the very beginning then flying speed of the model becomes paramount not only success but for model survival as well. And that's the point of all this. If a flyer is going to get "greedy" and try to get the highest launch then it becomes critical with the larger and heavier models to really give it the Heave Ho or a stall, snap and crunch is a very real and likely outcome sooner or later.

VE6WEM, I like the arms out, the side on position and the tail of the model down low indicating that your arm has some room to build up speed. The only part that can be improved is to set the right leg further back by about a foot. Then you could use the resulting support to push up and forward during the throw with more power all along your right side, down through your leg and onto the ground. As it shows now you are tending to still rely on the line tension to pull your arm up and around into the throw. In effect you're directing the line power into a vertical path but you're only going to be able to add minimal power of your own since there's no direct line down through your right leg to push from. In effect your lever has no supporting fulcrum.

[OVSS Boss]

The only problem with no throw launches, is that at the point of release, time=.0001 seconds, you have 0 airspeed. Read, anything external can have an effect on your ship, and I have seen guys that launch this way have some terrible results. One friend in particular, even though was a great contest stick, could be counted on to pop off on the average of about once in about 15-20 launches (every two to three contests), and never failed it happened in UNL at the Nats. The guys that turn loose the ship tend to use their right foot, which wads up their throwing motion, and no matter how hard they try, the ship out runs their throw of whatever power it is.

Marc

[OVSS Boss]

Mike,
Well, my war story is more soaring related. I am almost sure my shoulder , actually the bicep tendon partially tore from the scapula, let go in F3J at the Nats last year. But that was just the last straw, not the only reason. Just like you had played ball, both hard and soft, for about thirty five plus years (6~40 something) and I did train and work with horses in my life, they can sure tug on your arm. The actual incident, was typical launch, all set, and a team member was calling the runners for the tow. This just worked better for me as kicking and launching just did not seem to work. Well, this occasion, the flagger sent them at about 5 seconds to the horn instead of the usual 1-2 seconds that I normally did. I tried to hold and finally had to give up at about T-.5 seconds and had to relight. That release was totally out of my control and my shoulder and arm were along fo the ride. well, it did not hurt then, but later in September, bicep started to hurt, and just got worse. Felt like I had a c-clamp on it most all the time, could not launch stuff, holding ships became a problem, and jsut went down hill. Well, i should have gone in September to the doc, waited till December to see the orthopod and it was not until march 18 before the deed was done. Considering I am under 90 days right now, I am doing great, I have even, very softly thrown a DLG, really soft.

So I am pretty happy, but now my old ankle that was broke as a kid is giving me fits, so that might be next. Pure hell growing up!

Marc

[MDM]

here is a short video using mono

http://www.downeastsoaring.org/Videos/Launch.wmv

[screamin' eagle]

Was that a great zoom at the end of the launch, or what!

[BMatthews]

Marc/OVSS, I totally agree with your analysis and it's the basis of my harping on here about this topic. I only flew in RC sailplane contests for about 10 years before "I saw the light" and moved to electric assited soaring just for fun. But during that time I doubt if a single day of flying went by where I didn't see a great looking model either bite it on launch or come dangerously close to doing so just due to lazy launch technique.

The "bad habits" seem to stem from folks starting out with the lighter 2 meter poly ships that tend to get away with murder. Then they transition to the heavier stuff. In particular the aileron models just do not seem to tolerate sloppy technique as well as the poly ships but any of the larger and heavier models are in danger if not heaved properly.

PS: Just watched the video after posting the stuff above. The style in the video was darn close to perfect. If everyone launched with that sort of stlye and obvious effort (hear that grunt?) then we'd see an end to the dreaded mystery launch crashes. Great posture, positioning and foot spread.

[OVSS Boss]

Bruce,
I learned the throw thing early, learned it from Cecil Haga before I even had my first sailplane built. He would really woof on those Legionaires, I asked him why he threw instead of let the hi-start just pull. He gave me my first soaring lesson right there. Went from there.

Marc

[skewbe]

re:throwing or not. I'm not an expert on contests or the surrounding politics, but I would tend to think that in a winch or tow situation, the contest is primarily about who can fly the best, not who has the least torn up shoulder. I mean there's extensive rules about how many amps the winch can draw and battery specs, etc. etc., specifically designed to eliminate launching advantages.

Of course I find the whole competitve soaring thing a bit ironic. For what I get out of it it seems like competative meditating :) It shouldn't be a source of stress, physical or otherwise.

[OVSS Boss]

Actually Skewbe, there are no rules about winch power in the AMA book, there are safety rules, shut off switch, etc, but nothing about power. Now, the reality is that all winches are pretty much equal give or take since they all use ford long shaft motors and give or take the same diameter drum. Power is pretty much equal, the difference is how you utilize the energy available.

Marc

[skewbe]

Actually I was looking at the FAI rules, section 5.3.2.2
ftp://www.fai.org/sporting_code/sc4/sc4.f3bj.06.zip

They are pretty specific, like motor ohmage, SAE numbers for batteries, drum diameter, must be direct drive, towline composition, no cooling the motor or heating the battery beforehand or charging it just prior to launch, etc. etc.

[OVSS Boss]

You are correct there, FAI specs are thick as a book.

[rdwoebke]

I mean there's extensive rules about how many amps the winch can draw and battery specs, etc. etc., specifically designed to eliminate launching advantages.

When launch equipment becomes a level playing field (either on standard design winches or like here in the US soaring scene where most winches are pretty similar, or at least in a contest here you don't go bringing your own), other things have to be optimized to give edge in launch height.

One of the things to optimize is the actual event of the launch, the pre tension, the throw, etc. There are other things as well to optimize, and the nature of the zoom of course is important. Even a blind squirl like myself notices these kind of things, after watching really good pilots launch for 10 years.

Ryan "not a winch expert, but been around the block" Woebkenberg

[skewbe]

I'm just curious here, what kind of advantage does being able to throw a plane put one in?

Is "40 feet" significant enough to put a good pilot with no shoulder left out of the competition?

Does the throwing turn this into a javelin throwing competition?

What if one were to use a steep ramp and line stretch to get the plane going in the right direction quickly?

Can a blind squirl use binoculars during the competition? :)

[rdwoebke]

I'm just curious here, what kind of advantage does being able to throw a plane put one in?

Is "40 feet" significant enough to put a good pilot with no shoulder left out of the competition?


Good pilots with no shoulders left have other people throw the planes for them. Heck, even good pilots with shoulders left sometimes have other people throw the planes for them. I spent a lot of time watching launching at the last contest I attended, because I am a very poor athelete and have struggled with switching to a better launch method.

This is not a javelin competition. The throw is only one piece of the puzzle.

I'm pretty confident in saying that I am the lowest launching pilot on the field at any given contest.

This is all about omptimizing. You try to omptimize every area of the flight. Or at least think about them all. You end up breaking down parts of the flight even further. The launch becomes the pretension, the throw, the first part of the climb, the climb, the ping, the zoom, the transition from zoom.

Glide becomes hunt, thermal, float, turn, low tight lift work, "general lift work", reflex, etc.

Landing also becomes several different areas.

Ryan "who's results don't reflect any of this logic" Woebkenberg

P.S., I think some philosipher said knowing that you don't know is a higher level of enlightenment than not knowing you don't know...

[oakman7004]

I wrote up a big post a while back but the basics are that you need to stand chest to the line like an archer and hold the model in your fully extended arm back behind you. Feet should be about 3 to 3.5 feet apart for a good stable base to resist the line tension and so that the rear foot can push harder. For a right handed launch the left foot presses the pedal. When the line tension builds to about 60 lbs you HEAVE the model up on about a 45 degree nose up angle whle staying on the pedal. And I mean HEAVE! It's an F3B model turned slope racer and now it's back to it's roots. The wing will take it if it's not damaged internally from some slope misshap..


This says it ALL!

On F3B WC I tensioned the line so much (in the no wind launches) that I practically had to have my left foot on the winch (attached to ground) just not to slide away. The pedal I'm holding in my left hand. When throwing (DON"T fold that elbow) I lifted from ground. But hey, with that tension one can pull elevator from the beginning actually so much that the plane "overrotates" a bit to get back some of the tension lost just at release stage, using the extra speed to "retension" the line...and without stalling the plane... My friend Pasi Vaisanen is a expert at this!

I also use differnet amount of tension depending on the weather..in windy conditions release early and work the line on the way up...

NOTE! using a braided line is different...and just launching for fun don't need this aggressive tensioning...but throw/heave straight!
just my .02

cheers Jonas Ekman

[mlee8249]

Well, I think we got away from the original subject matter and that was if winches were plane killers. Suddenly, we are looking at competition and if this is really necessary. So, I want to go on record as saying this:

Are winches plane killers? No more than a hi-start or aero-tow. Every method has hazards and advantages. To me, once you let go of a hi-start, if the plane gets in trouble, you can't turn off a hi-start....but the result of trailing pieces for a hundred feet is sure awesome! In aero-tow, you better be a good pilot at following and maintaining distance, position, and line tension or it could be curtains....for two of you. On a winch, if your plane is fragile and you get a bit too much pedal into it, you get a lawn dart. If you learn how each method works, each method can be very safe, reliable and consistent.

As for the throw, let me say that you do not need an olympic javelin arm and legs of steel to be good at launching. I said you need to THROW for one very good reason. The short amount of guidance time your hand and arm provides to the plane during the throw is the most critical portion of the launch. Your throw must have the wings and nose at an acceptable level that the plane can assume when it leaves your hand and enters into self-sustained flight. If you are not level, off to the side you go. If you just drop the plane, it may drop and in the process, roll over to one side. Heck I even watched one of my teammates haul back and point his nose down just a hair and the line looped over the top of his nose at the moment of truth. The plane could not rotate up and simply rolled itself into a little ball on the ground in two seconds flat.

And while it is true that nobody is going to throw that plane at the same speed as the departing line, (or the plane would overshoot the line and pop off), this is not the point. The point is that you need that initial 4 foot of guidance your arm and hands provide to insure the plane is off to a safe launch. No grunting needed. No daily workout to develop the pecks, no rotator cuff injuries to worry about. Just guide the plane through the first few feet to give it an honest chance to fly. This applies to the hi-start or winch.

The other reason is what I mentioned earlier. If the line snaps at the moment of truth, your arm speed is the only thing giving the plane forward motion. Hopefully, enough to fly away from you and land safely when that line goes limp.

Ryan hit it on the head when you look at the overall flight. This is only one part. But this is the start of a great flight or disaster, depending on how you master the technique. When it comes to competition, given pilots of equal ability with planes of equal size, weight, etc., and the exact same air, he who launches highest, flies longest and wins.

Are winches planes killers? No, the guy launching the plane is.

Mike Lee

[OVSS Boss]

The question was asked, does 40 feet make a difference, well, it can. If my Insanity has a 25 to 1 (close guess) glide ratio, then that means I can cover 1000 feet more than another guy who did not get it. I realize that that is theoretical, but it is part of the game.

Marc

[mlee8249]

Oh, no doubt! I agree with you Marc. 40 feet can be victory or defeat and in competition, I won't give up a thing, if I can help it.Theory or not, I'm going to make it work for me.

Thanks, Marc!
Mike

[little flyer]

Here are some more launch photos. These were taken at SOAR's first contest of the year.

[BMatthews]

LF reffering to those 5 pics you posted.

#1 and 2 are excellent. #3 is so so but tending towards disaster. #4 is too late to tell. #5 is a possible disaster in action. I'll bet that even with the straight away release and rotation to vertical he still has the odd unexplainable sideways trip now and then.

Sport or contest the launch is still important. It's all about being sure that the airplane has the lift it needs to deal with the line tension of the winch at release. Tension on the line has the effect of increasing the apparent wing loading and thus raising the stall speed. Even with a straight ahead release where the model uses the line tension to accelerate to speed before rotating nose up it is still possible to have it rotate too soon or to suffer from a yaw or roll at the release due to cross winds or the like.

The only road to survival is consistently good launches for sport or contest flying. And the only guaranteed road to consistently good launches is a decent and appropriate throw for the size, weight and style of model.

[rdwoebke]

#3 is so so but tending towards disaster. .

Interesting. I wondered if somebody might make that comment. Now, if I am not mistaken, that person launching in #3 is Jim Bacus. He won the OVSS series last season.

:-)

So perhaps the throw is not as important?

:-)

Ryan

[little flyer]

Here is Jim Bacus. What you see is from one season. He is also sponsored by JR.

[jrerickson]

[QUOTE=BMatthews]LF reffering to those 5 pics you posted.

#1 and 2 are excellent. #3 is so so but tending towards disaster. #4 is too late to tell. #5 is a possible disaster in action.

Bruce,

I think there is a lot of hyperbole in your observation! Tending towards disaster? I agree that there is an optimized throw but there are many other ways that still work. As I stated earlier, having the wings level and having enough tension are the two critical items. I haven't seen a line break right on release before. I've seen a line break during tensioning, and I've seen a line break when the plane is 10' off the ground. In the first case the pilot just stumbles forward and hangs on to the plane, in the second case the alert pilot just does a loop and settles the plane back down.

The big "disaster" launches I've seen are where the plane goes off at an angle, the pilot lets up on the pedal, the plane stalls, then the pilot full pedals it into the ground. Ugly!

You can sit on the side lines at a contest like Visalia and see 500 launches of various "optimization" but the disasters are not that frequent.

John

[little flyer]

I agree with Jrerickson about the big disasters. The throw itself is very imporant. Once you have some altitude you are pretty safe other than wing failure. Here are some more photos.

[little flyer]

Here is a thread full of photos. Pick what you think is best and worst. Upload them and post here why they are good or bad.

http://www.rcgroups.com/forums/showthread.php?t=276610

[skewbe]

Here is a thread full of photos. Pick what you think is best and worst. Upload them and post here why they are good or bad.

http://www.rcgroups.com/forums/showthread.php?t=276610

Nothing like a relaxing afternoon of thermal soaring :)
http://static.rcgroups.com/forums/attachments/1/5/8/8/5/306970.thumb?qTu6oJVgnJ9hnaOaBmZjAwx8ZQgcoJSaMFHlE zcjMJp=

[little flyer]

I agree.

[mlee8249]

You guys are too funny!

Mike

[davidjensen]

I witnessed a different launch the other day. A guy brought a 3M scale ship with a wheel under it. He hooked it up to the winch and placed the ship on the ground in front of the peddel. He stepped on it and the ship was airborn in less than 10 feet and went straight up from there.

[little flyer]

That works well with scale as you can ROG, I have seen this done with a 1/4th scale ask 21. It helps if you hold the vertical at the base to get some tension before release.

[rdwoebke]

He hooked it up to the winch and placed the ship on the ground in front of the peddel. He stepped on it and the ship was airborn in less than 10 feet and went straight up from there.

My understanding of the history is this is how it used to be done all the time, back in the day. That ROG was the common way to winch all gliders initially. People learned that hand launching was less rough on the bottom of the fuselage and you could launch from a less perfect surface.

I too have seen ROG winch launching. If you have well cut grass, you don't even need a wheel, I have seen a SBXC ROG from the belly. We did hold onto the tail until tension was pretty good and then one guy kept the wings level.

Ryan

[MDM]

http://www.pbase.com/mdm/image/33927428.jpg

[BMatthews]

Interesting. I wondered if somebody might make that comment. Now, if I am not mistaken, that person launching in #3 is Jim Bacus. He won the OVSS series last season.

:-)

So perhaps the throw is not as important?

:-)

Ryan

With all due respect to Jim's proven flying performance I still stand by my comment. It may be that Jim is throwing with enough force despite his posture to get away with it. But the saving grace is that the nose is only angled up slightly. It's hard to judge from just a picture.

It's interesting to see that we are coming to the observation that there's two valid styles of launch.

There's the one where the model is thrown strongly upwards with the nose high and the flight path is strongly vertical right off the get go. For this style (which is my own personal style and the one I've been writing about all along) it is critical that the model be thrown with lots of energy to avoid a disaster.

Then there's the second style which is shown by Jim's launch and a few others in earlier pics where the model is still tensioned well but is launched more or less nose level or only slightly raised and straight ahead. In this method the launch speed is not as critical but you still want some speed so that the wings don't tend to get tipped by cross winds and such. With this second method the model uses the line tension to accellerate and then rotates up as the wings develop their full lift and due to the lower axis of pull on the tow hook.

The straight out and rotate method is valid I'll admit. But as pointed out we loose a little of the max height in the launch. A big deal? Probably not. But you may notice that in the F3B school of things most tend towards the vertical launches. But then we all know that F3B fliers are a bit fanatical.... :D

I think it's fair to say that both methods are valid for general or even contest flying since in the end a thermal makes up for any shortcomings or miscues in the launch.

The big problem, as I see it, is when a pilot tries to combine the less energetic throw associated with the level launch with a nose up attitude of the vertical style. When that happens disaster is but a moment away. Perhaps this is the message I should have been trying to get across earlier but didn't have the proper point of view to communicate it well.

When it comes to flying I have to admit that I'm not a contest winner. I often don't even place much above the middle of the pack. Mostly due to the fact that I can't land on the spot worth doody. When I was first learning I had my share of launch close calls and soon realized that I needed to throw harder. Since that time I have always had good launches despite cross winds, downwinds and other complications... well.... aside from the one close call where the wing caught my hat. No more hats at launch since that one... :D

Anyhow. we've probably beaten this one to death. I know I have. Take it for what you will but if my ramblings and rants save a couple of ships from dorking in at launch by getting some of the readers to reevaluate their launching styles I'll figure that this has all been worth while.

[little flyer]

These photos are hard to judge because you dont know how close they are to release. Also the day those pictures were posted it was blowing around 20 MPH so that might change the throw.

[evan_s]

I shot this sequence at Visalia, Oct 2005

[screamin' eagle]

With due deference to all who have posted in this thread, I nominate Evan's 8-word post as the winner.

[BMatthews]

With due deference to all who have posted in this thread, I nominate Evan's 8-word post as the winner.

Yeah, but that issue has it's roots at the time of the original design work and later on at the building board. And to some extent the talent of the guy on the pedal. It's hardly the winch's fault.

I've launched Gentle Lady's on a winch that would bend the wings of a fully glassed F3B bird. I had no problem but I was attentive to the initial line tension at launch and watched the wing bending and speed on the climb to regulate the pedal.

Your Stratos is hardly the sort of model that will fail during a launch like Evan's model. Your problem is far more likely to be due to an accelerated stall and severe sideways excursion if your lucky or a snap yaw roll and dork if you're not.

[skewbe]

"It's hardly the winch's fault."

Umm, why does the winch have to be on or off? Seems there arguably shoud be a provision for setting how much pull you get so it won't rip your wings off, at least in the year 2006 that ought to be possible, just need to deflect the line around an arm attached to the switch and turn the dial to how many lbs (or kilos) your plane is designed to handle.

The fact that winches haven't evolved in 50 years isn't the winches fault, true, but they could probably be improved upon to give more consistent results with a wider variety of planes, i.e. ones not built around a 2x4 :)

I had a moped that snapped a throttle cable once. I managed to wire it to full on in the middle of my trip and drove it for the rest of it's life by regulating the engine speed with the kill push button by the thumb (tap it to idle, take thumb off for full throttle, there wasn't much difference). I often wondered what a 600HP geo metro with an on-off switch instead of a throttle would be like :)

[LVsoaring]

I demand proper recognition here! Evan S was indeed the superb photographer, but it was I who was the unfortunate pilot!

Cheers!
Rick


PS....Hey Evan, how's it goin?

[LVsoaring]

And Bruce, your points are well taken and you are absolutely correct. A post mortem revealed poor workmanship (my fault) in the center wing joiner area. I just lost my Riser 100 on the winch, this time due to failure of a nylon bolt, but I am glad to say my building techniques and wing structure did not fail until impact. Hard lessons, but well learned!

Rick

[evan_s]

I didn't want to identify you, Rick, without permission! It's been going ok, thanks.

Rick, blame the winch - - it was a power surge, yeah, that's it...a power surge.

Visalia will be having a woody class in October. If I don't destroy my Paragon in the meantime, I hope to be there.

Evan

[screamin' eagle]

Visalia, eh? Wanna carpool, Evan? I must have gotten at least a three minute flight this afternoon with your help. :D

[spatial]

Umm, why does the winch have to be on or off? Seems there arguably shoud be a provision for setting how much pull you get so it won't rip your wings off, at least in the year 2006 that ought to be possible, just need to deflect the line around an arm attached to the switch and turn the dial to how many lbs (or kilos) your plane is designed to handle.

Dunno how old the winch we fly our club comps off is but it has a belt drive with an adjustable arm which allows you to adjust the tension to suit model and/or wind. maybe US flyers are too caught up with 'real balls' and 'long shafts' :rolleyes: ;) just sounds like bad seventies p0rn to me.

[screamin' eagle]

Sunday I manned the pedal and sticks for my first solo winch launches. Plane was an Airtronics Aquila. My instructor/spotter, Evan_S, said the wings were getting pretty bendy at the top of the launch. It took me a few tries to get it to a decent height. There were a few pop-offs. I expected the line to be much stretchier, but it had very little in there. It made tossing difficult unless timing was perfect, otherwise the plane would be snatched out of my hands early. The wind was coming at our backs part of the time as well, which added to the degree of difficulty.

All in all I can definitely see the dangers. Catching a thermal or two made it real fun, though.

[histarter]

Dunno how old the winch we fly our club comps off is but it has a belt drive with an adjustable arm which allows you to adjust the tension to suit model and/or wind. maybe US flyers are too caught up with 'real balls' and 'long shafts' :rolleyes: ;) just sounds like bad seventies p0rn to me.
I believe your XXX comment is very accurate. Its America's Tim The Tool Man's attitude of "More Power" (with infinity the only limit)! :eek:

[OVSS Boss]

And the problem with that is??????HuhHuhHuh!

[rscarawa]

Why is it that the planes do not have a device for releasing when line tension becomes too great?

Work with me here. Imagine if your tow hook was mounted to a door on the bottom of a wood fuse. The door would be hinged up front and would be secured by some sort of latch with known breaking strength or a magnet that could be adjusted. If the line strength was too high, the door would open allowing the hook to drop down and release the ring. Then a light spring would pull the door shut. If more line tension was desired, then you could add more magnets to make the door stay shut under higher tensions. Not sure how this would work for fibre.

Second idea. use a tow hook with a washer or wheel collar on it to control how far forward the ring can go on the hook. This would allow the hook to bend and release the hook if the tension got too high. If less tension was desired, then the collar would be placed further back. This might require placing the hook in a different hole.

Has this been tried?



Scot

[rscarawa]

And the problem with that is??????HuhHuhHuh!
Calm down Beavis!

[BMatthews]

Why is it that the planes do not have a device for releasing when line tension becomes too great? ....

You're trying to deal with a problem that does not or should not exist.

Tension is easily controlled with the foot on the winch pedal coupled with an eye that judges the wing bending and flight speed.

Trying to set up the tension for each model would be far more likely to result in lots of far more dangerous premature releases that would end up with more busted models than the current small number of broken wings. This is because everyone would want to work UP to the right release tension.

It also takes away from the ability to zoom the model up the line. All else being equal our models develop more lift at higher speeds. The faster the model goes up the line the better it is within reason. A hook that lets go to easily would prevent the flier being able to properly fly it up and get the desired zoom launch.


The only proper way to control the pull on the model's wings is a tension adjustable winch. Either a mechanical setup like the belt one mentioned earlier or an electronic limiter on the motor so that instead of pulsing the pedal manually an electronic speed and current control would do the pulsing for us and all we would have would be a "gas" pedal. Push a little on the pedal and the line tension rises to a few lbs and stays there even with the motor stalled. Push harder and the motor pulls more. So a Gentle Lady flier could step up and ask that the line tension be preset for X lbs. They stomp on the pedal and they can get from 0 up to their requested max. The f3b guy comes up to the same winch and sets it for the Full Monty and gets the max pressure.

The motor is set to work with a torque sensing circuit so that it uses whatever power it needs to draw the line in fast enough to maintain the torque being requested by the "gas" pedal.

That way there's no popoffs due to mis set hooks. But it does mean that it would be up to each flier to ask for or set the line pull before flying. I can see some problems there when confusion arises during the heat of battle but when properley applied it would allow one super winch to be used by any airplane, and just as importantly, any flier of any ability.

[rscarawa]

I am just saying that accidents happen, why lose a plane over it. Winds gust, feet slip. I figure if you know your wing can handle 50 lbs, you can setup up a release to let go at 35-40 lbs. Every structure has a limit somewhere.

I have never used a winch, just playing devil's advocate.

[spatial]

you could always use 35lb test winch line ;)

[skewbe]

you could always use 35lb test winch line ;)

...or a leader that makes the final connection to your hook...

[rscarawa]

True. I just figured that people did not like to change the line they used.


Scot

[BMatthews]

I seem to recall that as part of the move to control the "Winch Wars" in F3B that they used a certified weak link in the lines for a season or so back in the 70's or something like that. It didn't last long and I'll bet that it was because of the carnage that resulted.

rscarawa I can understand that you are trying to find a way to save the wings but a hook that releases suddenly is not the way to do it. By far the most likely time for the line pressure to reach it's peak is just as the model is released and noses up to vertical. It is also the most dangerous time to have the line pop free for ANY reason. Next to stalls and pivots on the launch the early pop off has broken more planes than any other cause from what I've seen.