Do you have a fear of winch launching?

[RCFlybry]

I'd read a lot of posts about people shearing wings in half off of winch launches. After a flying buddy and I constructed our winch with the use of a Ford longshaft starter motor #3115, and a high power Interstate 12volt battery I had images of balsa pieces floating overhead. After spending one full day with the winch, getting used to the pedal, and learning how to launch gently I was pleasantly surprised. We've launched Gentle Ladies, Oly2's and my Bird of Time ( Kit Version) with great success. Approx. 130 launches later and still no problems. I actually prefer it over high starts as I feel we put less stress on the wings, and achieve much higher launches. Ray Hayes a well known sailplane pilot responded with this email:
Back in the days of large contests, when Otto Heithecker with his Challenger and Jeff Mrlik with his Astro Jeff used to battle it out, they both launched to equal height in wind or calm. Recently, I asked Otto why his wings never bowed during launch, even in 20 + MPH winds, his answer, " I took it easy". But, believe me, his launches were very high. His joiner rods were 5/32 piano wire. The trick is not to reel in much tow line during launch, let the wings do the work.
Just some food for thought.

Bryan

[kingbee]

A winch is by far the most versatile launch system. ANYTHING can be winch launched, from Gentle Ladies to the latest bomb proof composite ships. They all take a different technique, that's all. The weaker planes in particular take a bit of skill and finesse. For beginners it's one more thing to worry about, so maybe a hi start is best for learning. But once you can chew gum and tap dance, a winch is the way to go.

These days a lot of people seem to think that if a plane can't take a full pedal launch it's not winchable. Makes you wonder how they drive!

Personally, I fly alone, so a winch is not really practical. But If there was a glider club around with a winch, my hi start would rot from disuse.

Cheers,
Dave

[Jack Hyde]

If you winch a plane that has wings that cannot stand a full pedal launch you don't know how much pedal is too much until you break something. You can watch for bending , carefully sneak up on pedal power - each flight a little more pedal. But you won't know how hard you can winch your Gentle Lady until you break it. The answer is to stay way on the safe side and avoid trying to push it to higher and higher launches. I have winched about every kind of plane and have folded 3, all had repairs of suspect structural strength. You can break composite planes if you try hard enough. I haven't done that but I saw one pop at the top of a launch.
Dave,
I fly alone mostly and set up my winch 98% of the time. I drag out a histart a few times a year to see what I am not missing. Winch setup takes 5 mins and a little lifting. Winch cost is another consideration but if you fly for 10 years its pretty reasonable.
I used to drive 100 -200 miles each way on week ends to get to a winch - I love them but not the driving so I got a winch for home.

[viti]

the aid of weak links can be a real wing saver for the g/l type wings,,better to break the link than a spar



viti

[kingbee]

Jack,
You're right, the real reason I don't use a winch is that I can't afford one. If I had one I'd gladly lug it around. Setup and takedown is really no worse than a hi start.

In addition to better launches and greater versatility, here's some more winch advantages:

1. They easily adapt to any size field.

2. After release, the chute can be run down close to the turnaround. This is a great help if a) there's a crosswind and the chute would drift into tees, cars, whatever; b) the field has weeds or brush that would snag the line; c) you share your field with power flyers (as I do) and the line might oterwise drift across their runway.

3. Opinions vary on whether hi starts work in cold weather (freezing or below) but winches don't care what the temp is.

There are probably more but if I don't shut up I'll wind up talking myself into buying one :)

Cheers,
Dave

[fprintf]

That grasshopper winch looked pretty neat. About the same setup time as a histart and probably higher launches too. My histart doesn't work in the cold weather at all (CT gets pretty cold in winter) so it is either electrics or using a winch (grasshopper or standard variety) when it is colder that 40 degrees or so.

[RCFlybry]

The answer is to stay way on the safe side and avoid trying to push it to higher and higher launches.

I agree with you Jack, On the first day we put the Gentle Lady up on the winch we flexed the wings on it the first couple of launches. We figured that we were pushing the edge a tad and backed off on the winch pedal. We've since continued to launch all of our sailplanes at pretty much the same power. The toughest thing was getting used to the pedal, and how to tap the plane up the line. After we got used to the pedal, all of our launches have been pretty consistent. We've been satisfied with the height that we are getting on launch, and don't intend on pushing the winch any harder than we are. I like the Heithecker approach. Take it easy and let the wings do the work.

Bryan

[aeajr]

This is my first year flying anything as well as my first season with a sailplane. The hi-start and I are friends. Never hurt the plane with my hi-start.

Me and the winch are .... not currently friends. On my third winch launch a wrecked my Great Planes Spirit. It has been on the bench since. Slowly I am getting it back together. I will test it on the hi-start before I try a winch again. This time I will get more help. I thought I was ready, but I was not.

[portfoxdesign]

Guys
Just adding some input, i have built an inner tube hi-start which works just fine with my 2.5m balsa plane, cost nothing at all.
I have used home made winch's and also production ones. I agree the winch is the better, but they dont need to be expensive. I'm just building another after beign away from the hobby for a bit. I have located my starter motor free of charge, found some steel square section and have nutted out the plans from drawings on the net, looking at other pilots winchs and just thinking how it would best suite the situations i will be launching in.
As for launching , you get the feel for it. Tapping the pedal just enough to keep the model moving forward and up, like previous pilots have said, use the wings, thats what they are made for.
Keep the tension on it, while letting her go and also up the ascent.
If you want to drive your plane up, just progress in stages until your at the velocity you want.
Just keep in mind its only the launch, the thing you want to make sure is right is the the thermal hunting and staying aloft in one.
There is nothing better than having a great flick of the end of the launch, grabbing at thermal and speeding an hour or so in the air.

Steve

[rdeis]

Originally posted by Jack Hyde
But you won't know how hard you can winch your Gentle Lady until you break it.

But you *can* tell that you're pushing the limit. If you're working it too hardm the covering on the top of the wings will wrinkle up as the wing flexes and it goes slack.

That's one advantage built-up ships have over composites- they'll bend before breaking- if you're paying attention you can back off and suffer no harm.

[rpd]

I flew powered planes in the 70's and got out around 75. I am retired now and decided to try soaring when I got back to model building a couple of months ago. I built the kit version of a Spirit Elite. I made the wing one piece and was using high-start only. I read the horror stories of folded wings and even saw it happen to a couple of planes at a contest. This week one of our club members set up the winch and I tried it. I love it. Higher launches with no problems. My biggest problem was remembering to keep stepping on the switch. I was used to the high-start doing all the work. By the way, imagine how thrilled I was when I found that the AMA had moved to Muncie-- 20 minutes from home. Pat

[Jack Hyde]

rdeis,
All structures bend before they break. When a wing is moderately loaded it bends , the stucture is in the elastic deformation range . When the load is reduced the bending decreases, like a spring returning to its relaxed shape as it is unloaded. Composite materials are elastic just like wood. Think of archers bows - both wood and fiberglass bows work fine. Some materials used in composite wings are pretty stiff and the wings are designed to be stiff. I have an Alcyone 3m that bends enough to be scary when winched.
Most wings break at the top of the launch so there is no way to observe the covering to see if it is wrinkling at the critical time. o the other hand you can see the covering wrinkle early in the launch which is helpful in a very qualitative way. If the covering wrinkles does that mean the spar or joiner is about to break.? Not necessarily.
I am by no means saying you can't winch builtup wings - I do it regularly. But it is a little spooky knowing you will never know how close you are to breaking a wing until you do it. That goes for composites as well. Its a hazard of the activity.

[viti]

[.
I am by no means saying you can't winch builtup wings - I do it regularly. But it is a little spooky knowing you will never know how close you are to breaking a wing until you do it. That goes for composites as well. Its a hazard of the activity. [/B][/QUOTE]



this hazard can be avoided with the use of weak link
,problem is knowing what strength the link should break at??


viti

[lincoln]

You CAN get some idea of how close you are to breaking the plane if it's a flexible wing. Stiff wings can break before you can see the bend. Lots of wood planes have thin wing rods that flex enough to see.

If I'm not mistaken a 3115 is a 12 volt wind. I have a 12 volt wind winch which no one in our club will use because they are used to the hotter 6V winds (with a 12V battery!). The 6V eats novices Spirits and Aspires with regularity. But it's still easy to control for me, even with my Oly 2 with the original 7/32 wing rod.

I've never been able to get people to practice tapping their foot on the switch with the winch turned off. I think it would really help as it's not so easy to do controlled, regular tapping while standing mostly on one foot. And then when you add in the throwing and flying parts....

I've been using winches for many years, but I only blew up one plane, and that was on purpose as I wanted to see just how hard I could push it. Answer was pretty hard. It did have a rather wide spar. Had a terrible airfoil, too.

[RCFlybry]

If I'm not mistaken a 3115 is a 12 volt wind
It is and we chose to go this route on purpose. It's still powerfull enough to break a wing for sure, but is less powerfull than the 6 volt wind with a 12 volt battery. It's just the ticket for us though as we don't have any composites and mostly fly built up Nostalgic ships.

Bryan

[rdeis]

Originally posted by Jack Hyde
All structures bend before they break. When a wing is moderately loaded it bends <additional science deleted>

Point is that wood spars are, in general, much more flexible that composite ones. This is especially true when using a composite joiner rod instead of a metal one.

That simply means that while composites are more likely to be strong enough you can't break them, wood ones are more likely to warn you before letting go.

It's just like thermalling- listen to the airplane and do what it tells you to do. If the top covering is wrinkling on a launch, that's letting off pedal and/or giving down elevator.