Post by Ed Anderson on Mar 22, 2009 14:44:28 GMT -5
> LEARNING TO USE A HI-START
> by Ed Anderson
> aeajr on the forums
>
> I think one of the reasons we don't see more people flying
> unpowered sailplanes/gliders is that they don't understand
> how the planes are launched. Once someone tells them about a
> hi-start or a winch, they shy away, again, because they don't understand.
>
> I LOVE hi-start launching my Spirit 2 meter and my Sagitta
> 600 2 meter and even my 3 meter Airtronics Legend. It is
> such a thrill to see the plane climb up to the sky then just
> silently float off the line like a sailboat. I find the hi-start easier
> than the club winch and I get great launches. If I can do it, you can do
> it.
>
> These links may be helpful for background about hi-starts.
>
> What is a Hi-Start
www.hobby-lobby.com/histart.htm
>
> This product review of the AVA RES Sailplane has some good
> photos of a hi-start launch and a video of an actual launch.
> www.rcgroups.com/articles/liftzonemag/2004/mar/ava/Ava1.wmv
>
> Videos of actual hi-start launches
> www.youtube.com/watch?v=JGvhxIICR48&feature=related
> portfox.rchomepage.com/gallery/movies/Stepp3-launch.wmv
>
> By comparison, Typical Winch launches
www.youtube.com/watch?v=9kbpC33DNxU
This is a strong winch launch
> static.rcgroups.com/gallery/data/500/7716mono.mpg
>
>
> HI-START LAUNCHING - Getting Ready
>
> First, let's be clear, what I will be focused on is NOT competition
> launches. I am talking about safe sport launches. I am
> sure someone will comment about maximum altitude and such.
> I just want to help you get in the air safely.
>
> Second, if possible, get a coach/instructor if one is
> available and ignore all of this. This is ONLY intended for someone
> who is unable to get help and must learn on their own.
>
> Third, your plane must already be well trimmed and flying
> straight and even from a hand throw. If you have been having
> problems with getting good hand launches, ask questions here. It isn't
> hard but there is a definite techniques to it. Getting good at hand
> launches is important to good hi-start launches. Fail to do this and
> the hi-start will turn your plane to junk!
>
> Fourth and very important, make sure your tow hook is in the
> forward most hole that your plane has. If you only have one
> tow hook
> location check to see that it is a little in front of the CG
> of your plane. about 1/4" to 1/2" is a
> good starting point. This will give you a more controlled
> launch than the
> more rear, competition positions. You can move it back
> later, once you become comfortable with the hi-start.
>
> OK? We understand the goal here? Safe and gradual build
> up. Our goal is control, not ultimate height! That will
> come later.
>
>
> STARTING SMALL
>
> I don't know what hi-start you have or how big it is, but if
> it is a "full size" hi-start it probably has 30 meters/100
> feet of elastic, usually latex rubber tubing, and 100-125
> meters/300-400 feet of line. There is no reason why you
> can't start right in with this full size unit. However, if
> you feel this is
> an awful big thing to handle on initial launches without a coach
> you can start smaller. You can either get an up-start which is a
> smaller version of a hi-start, or take your big hi-start and
> only use part of it for your initial launches.
>
> SHORTENING YOUR HI-START
>
> Remember, this shortening step is optional.
>
> To take a large hi-start and only work with part of it, we will reduce the
> length of the line and elastic that will be involved in the launch. You
can
> cut the line, or replace it with a smaller piece during the training
phase.
> DON'T CUT THE TUBING! We want to preserve the tubing, or
> other elastic, as a single piece as it will work better when you are ready
to
> use all of it. We > will just change how it is secured so we are only
using part
> of it.
>
> First the line. You can either cut the line, or buy another piece of line
> that is shorter. Line is cheap and it can be useful to have line of
> different lengths, so I will suggest you pick up some masons line, or any
> braded nylon or Dacron line at any hardware store. You want something
> with a working strength of 50 pounds or more. Nylon mason's
> line is
> typically
> around 100-150 pounds working strength. Bright colors will
> make it easier
> to find the line in the grass. Mine are hot pink and hot
> orange.
> You can also use 50 pound test monofilament fishing line for
> your 2 meter
> plane but it will be harder to find in the grass than
> mason's line. I
> suggest you make up a couple of 50 foot lengths. As we
> progress you can
> join them using a knot, or I like to use heavy duty fishing
> snap swivels.
>
> To shorten the elastic I simply loop the elastic over the
> spike 2-3 times at
> some reduced length. Works fine.
>
> LAUNCH INTO THE WIND!
>
> Always launch into the wind. Whether it is a sailplane on a
> hi-start, a
> parkflyer or a Boeing 747, we always launch into the wind.
>
> For learning purposes I would say calm air to 5 mph would be
> a good starting
> range. Gusty or swirling wind that changes direction a lot
> is going to
> complicate learning. Once you are accomplished, these will
> be much less of
> an issue. I have spent whole days hi-start launching in 15
> mph winds which
> can
> really help take the plane high. Launches will be higher
> with a breeze
> than dead calm air.
>
> One of the advantages of a hi-start over a winch is that it
> is easy to
> adjust your launch related to the wind. When your plane is
> in your hand,
> check the wind direction and move left or right so your
> launch will be as
> directly into the wind as possible. You can move right or
> left to adjust to
> a changing wind direction.
>
>
> SETTING UP THE HI-START
>
> Now we want to get to deploying the hi-start in preparation
> to launch your
> sailplane. You are going to stake one end of the hi-start
> into the ground
> using a 10-16 inch spike, large tent peg, screw in dog chain
> anchor or some
> other method. Make sure the stake that you put into the
> ground is secure
> and has a large enough washer on it so that the ring on the
> hi-start will
> not
> pull off the stake. As extra insurance, you can also loop
> the elastic over
> the
> spike for extra security. I usually do this.
>
> If you start small, say 15' of elastic and 50' of line it
> might feel a lot
> easier to control, and the launch will be lower and the
> energy smaller.
> Again, this is just an assisted hand throw. We will use
> this length
> combination for this discussion. Remember that I am
> assuming your plane
> is well balanced and trimmed and that you can reliably hand
> throw it and
> control that hand throw from your radio. (If you are not a
> master of the
> hand
> throw, put this down and go work on that!)
>
> If your plane is flying well from a hand launch and your tow
> hook is a
> little in front of the CG then I am going to suggest that
> you launch with
> all
> controls at neutral trim, or wherever the plane flies best
> from the hand
> throw. Remember you don't use the elevator to take the
> plane up, the lift
> of the wings will do that. In fact, as we will discuss
> later, if you have
> problems with pop-offs, you can put in 3-4 clicks of down
> elevator to slow
> down the rotation of the plane on the initial launch. Just
> don't forget to
> take it out once you are off the hi-start.
>
> Video example of a hand launch
> www.youtube.com/watch?v=ixwur8lakBM&feature=related
>
>
> If you get your wings out of level on the launch, the plane
> will tend to go
> right or left when you throw it, just like a bad hand throw.
> Use the rudder
> to get it back to center and work on getting a level throw.
>
> It is easy to control the launch force of a hi-start by how
> far back we pull
> it, which will determine the stretch on the elastic and the
> energy of the
> pull Do exactly what you would do on a hand throw.
> Basically flat firm
> throw
> with level wings. The hi-start will continue the pull to
> accelerate the
> plane
> giving the equivalent of a strong hand throw. However as
> the hi-start will
> pull it faster than a hand throw, it will start to climb.
> This is what we
> want.
>
>
> TIME TO LAUNCH
>
> Be sure your receiver and radio are turned on. Complete
> your range check
> and make sure all surfaces are moving in the right
> direction. Now you can
> hook the line to your plane's tow hook and pull back a
> distance equal to the
> length of the elastic, 15 feet in our example. You should
> feel a pull on
> the line, but should have no trouble holding the plane in
> one hand. I like
> to
> grip my plane under the wings and hold it with the wings
> over my head.
>
> Now, check to make sure all of your controls are working
> again. If
> necessary, use your mouth to move the sticks and see that
> everything is
> working. Check the trims on your radio to make sure you
> have not bumped
> them out of place. Do this on EVERY launch ... forever!
>
> Stand firm, don't walk or run with it, and just give it a
> straight. firm,
> flat throw, controls at neutral just like a hand throw. Get
> your hands to
> the controls on the radio ready to guide the plane, but
> don't over control
> it.
> The plane should go out just like a hand launch, only with
> more speed.
> It should naturally climb a little. It should just fly off
> the end of the
> line. Let it glide out and drift down naturally, just as you
> would on a hand
> throw, just further. Be sure you have enough space in front
> of the
> launch to allow it to do this. You don't want to have to
> turn on you first
> hi-start to avoid hitting things.
>
> You just completed your first hi-start launch.
>
> How did that go? If it went left or right, you tipped the
> wings when you
> threw it or your plane is not trimmed to fly straight. Work
> on it at this
> length until you go out level and true every time.
>
> Build up the strength of the pull over several launches.
> Pull back one
> length of the elastic. Launch from this until you are
> comfortable. Then
> pull it back 1 1/2 lengths of the elastic. Then try it at
> twice the length
> of the
> elastic. Make sure you are going out straight and level.
> For a 15 foot
> piece of elastic that would be a 30 foot pull.
>
> Then slide another 15-20 feet of tubing into the working
> area of the
> hi-start and add another 50 feet of line. You are now in
> up-start range
> with 25-40 feet of tubing and 100 feet of line. The plane
> will launch
> higher with this arrangement. You change nothing, let the
> hi-start do the
> work. Just don't forget to get the plane a strong push/throw
> as you release
> it. Don't just let go.
>
> Keep adding elastic in whatever increments you like till you
> get to the full
> length. Add 3-5 times as much line as elastic till you add
> it all back.
> Again a typical full size hi-start is 60 to 100 feet of
> elastic 250-400 feet
> of line.
>
> How far back you want to pull depends on the make and
> diameter of the tubing
> on your hi-start. If this is a commercial hi-start, read
> the makers
> recommendations and follow them. In general, with 1/4 -5/16
> OD latex
> tubing, pulling back two to three times the length of the
> tubing should be
> plenty for your 2 meter plane and should not over stress the
> tubing. If you
> are
> using bungee cord you will likely not be able to pull back
> that far as the
> cloth
> covering constrains it and bungee is typically much stronger
> than the latex
> tubing.
>
> If you are using heavier tubing such as 3/8", 7/16" or 1/2",
> a pull of 1
> 1/2 times the tubing length may be all you would want to do
> with a 2 meter
> plane. My hi-start rubber is 3/8" and I only pull back about
> 1 to 1 1/2
> times the length of the tubing to launch my 2 meter planes.
> At that pull I
> can barely
> hold the plane. I measured it once at 14 pounds of pull
> which is stronger
> than needed for a Spirit, for example. If you feel like
> measuring, a pull
> of 3-5 times your model's weight is a good target, or 6-10
> pounds for the
> typical 2 meter starter plane. I have launched my Spirit at
> up to 14 pounds
> of pull, as measured with a fisherman's scale.
>
> Pop-Offs:
>
> A pop-off occurs when the plane rotates so much during the
> launch that it
> releases the line early and "pops off" the line. This can
> happen anywhere
> but I have usually seen it within the first 150 feet of the
> launch. Pop
> offs can be
> tricky to control. The plane may fly up at an extreme angle
> then stall and
> want to dive for the ground. More often it will pop off and
> go into a loop
> to the rear, behind you. I have found that most of the
> time, if this
> happens, you are best served to just help the plane finish
> the loop rather
> than
> trying to prevent it. Fighting the loop often takes so much
> energy out of
> the plane that it will stall and you are fighting to keep it
> from crashing
> to
> the ground.
>
>
> If the plane starts popping off too soon, try putting a
> click or two of down elevator on the trim before you launch.
> Also make sure
> your tow hook is in FRONT of the CG. About 1/4-1/2 inch is
> enough. The
> likelihood of a pop off will increase with the power of the
> launch due to
> the rotation of the plane from level to climb, so let's get
> it under control
> early. That is why we build up slowly.
>
> As the pull gets stronger, the plane will fly out faster and
> the lift of the
> wings will take it higher naturally. No need to throw it
> up, it will go up
> on its own. You can launch the plane at a more elevated
> angle as you become more comfortable with the hi-start and
> get to know how your
> plane launches.
> Up to a 45 degree angle works well. Just remember that the
> steeper the
> angel the more important the throw. Don't just let go, give
> it a
> good push.
>
> I have over 500 launches with my Spirit, Sagitta and Legend.
> I launch at 20
> to 45 degree up angle with neutral controls and the forward
> tow hook
> position. My planes climb beautifully and I don't give up
> much to the winch,
> if anything.
>
> Using my smaller launcher (25' tubing and 100' line) I get
> 100+ feet
> launches depending on the wind, without a zoom at the end.
> With the larger hi-start (100' 3.8" tubing and 400' line)
> I estimate I go
> up 350-500 foot launches, depending on the wind, and can
> zoom off of the end
> to gain more height if I want.
>
> I was afraid of the hi-start but now I really enjoy it. If
> you have someone
> to coach you through the first few launches you will be
> fine. If you don't,
> try this method.
>
>
> The angle method for placing the tow hook
> www.rcgroups.com/forums/showpost.php?p=7107908&postcount=15
>
> Here is another informational post for those who like more
> technical detail
> The Physics of Hi-Starts
>
www.charlesriverrc.org/articles/design/thingywilliamson_histartphysics.htm
>
> Sailplanes are Wonderful!
> www.rchangout.com/forums/showthread.php?t=5356
>
> If you are new glider pilot, this is a great resource:
> forums.flyesl.com/topic.asp?TOPIC_ID=224
>
> Video of 4M glider launch - Throw is bad, but he
> gets it into the air.
> www.youtube.com/watch?v=T-sYXc9gbUE
> by Ed Anderson
> aeajr on the forums
>
> I think one of the reasons we don't see more people flying
> unpowered sailplanes/gliders is that they don't understand
> how the planes are launched. Once someone tells them about a
> hi-start or a winch, they shy away, again, because they don't understand.
>
> I LOVE hi-start launching my Spirit 2 meter and my Sagitta
> 600 2 meter and even my 3 meter Airtronics Legend. It is
> such a thrill to see the plane climb up to the sky then just
> silently float off the line like a sailboat. I find the hi-start easier
> than the club winch and I get great launches. If I can do it, you can do
> it.
>
> These links may be helpful for background about hi-starts.
>
> What is a Hi-Start
www.hobby-lobby.com/histart.htm
>
> This product review of the AVA RES Sailplane has some good
> photos of a hi-start launch and a video of an actual launch.
> www.rcgroups.com/articles/liftzonemag/2004/mar/ava/Ava1.wmv
>
> Videos of actual hi-start launches
> www.youtube.com/watch?v=JGvhxIICR48&feature=related
> portfox.rchomepage.com/gallery/movies/Stepp3-launch.wmv
>
> By comparison, Typical Winch launches
www.youtube.com/watch?v=9kbpC33DNxU
This is a strong winch launch
> static.rcgroups.com/gallery/data/500/7716mono.mpg
>
>
> HI-START LAUNCHING - Getting Ready
>
> First, let's be clear, what I will be focused on is NOT competition
> launches. I am talking about safe sport launches. I am
> sure someone will comment about maximum altitude and such.
> I just want to help you get in the air safely.
>
> Second, if possible, get a coach/instructor if one is
> available and ignore all of this. This is ONLY intended for someone
> who is unable to get help and must learn on their own.
>
> Third, your plane must already be well trimmed and flying
> straight and even from a hand throw. If you have been having
> problems with getting good hand launches, ask questions here. It isn't
> hard but there is a definite techniques to it. Getting good at hand
> launches is important to good hi-start launches. Fail to do this and
> the hi-start will turn your plane to junk!
>
> Fourth and very important, make sure your tow hook is in the
> forward most hole that your plane has. If you only have one
> tow hook
> location check to see that it is a little in front of the CG
> of your plane. about 1/4" to 1/2" is a
> good starting point. This will give you a more controlled
> launch than the
> more rear, competition positions. You can move it back
> later, once you become comfortable with the hi-start.
>
> OK? We understand the goal here? Safe and gradual build
> up. Our goal is control, not ultimate height! That will
> come later.
>
>
> STARTING SMALL
>
> I don't know what hi-start you have or how big it is, but if
> it is a "full size" hi-start it probably has 30 meters/100
> feet of elastic, usually latex rubber tubing, and 100-125
> meters/300-400 feet of line. There is no reason why you
> can't start right in with this full size unit. However, if
> you feel this is
> an awful big thing to handle on initial launches without a coach
> you can start smaller. You can either get an up-start which is a
> smaller version of a hi-start, or take your big hi-start and
> only use part of it for your initial launches.
>
> SHORTENING YOUR HI-START
>
> Remember, this shortening step is optional.
>
> To take a large hi-start and only work with part of it, we will reduce the
> length of the line and elastic that will be involved in the launch. You
can
> cut the line, or replace it with a smaller piece during the training
phase.
> DON'T CUT THE TUBING! We want to preserve the tubing, or
> other elastic, as a single piece as it will work better when you are ready
to
> use all of it. We > will just change how it is secured so we are only
using part
> of it.
>
> First the line. You can either cut the line, or buy another piece of line
> that is shorter. Line is cheap and it can be useful to have line of
> different lengths, so I will suggest you pick up some masons line, or any
> braded nylon or Dacron line at any hardware store. You want something
> with a working strength of 50 pounds or more. Nylon mason's
> line is
> typically
> around 100-150 pounds working strength. Bright colors will
> make it easier
> to find the line in the grass. Mine are hot pink and hot
> orange.
> You can also use 50 pound test monofilament fishing line for
> your 2 meter
> plane but it will be harder to find in the grass than
> mason's line. I
> suggest you make up a couple of 50 foot lengths. As we
> progress you can
> join them using a knot, or I like to use heavy duty fishing
> snap swivels.
>
> To shorten the elastic I simply loop the elastic over the
> spike 2-3 times at
> some reduced length. Works fine.
>
> LAUNCH INTO THE WIND!
>
> Always launch into the wind. Whether it is a sailplane on a
> hi-start, a
> parkflyer or a Boeing 747, we always launch into the wind.
>
> For learning purposes I would say calm air to 5 mph would be
> a good starting
> range. Gusty or swirling wind that changes direction a lot
> is going to
> complicate learning. Once you are accomplished, these will
> be much less of
> an issue. I have spent whole days hi-start launching in 15
> mph winds which
> can
> really help take the plane high. Launches will be higher
> with a breeze
> than dead calm air.
>
> One of the advantages of a hi-start over a winch is that it
> is easy to
> adjust your launch related to the wind. When your plane is
> in your hand,
> check the wind direction and move left or right so your
> launch will be as
> directly into the wind as possible. You can move right or
> left to adjust to
> a changing wind direction.
>
>
> SETTING UP THE HI-START
>
> Now we want to get to deploying the hi-start in preparation
> to launch your
> sailplane. You are going to stake one end of the hi-start
> into the ground
> using a 10-16 inch spike, large tent peg, screw in dog chain
> anchor or some
> other method. Make sure the stake that you put into the
> ground is secure
> and has a large enough washer on it so that the ring on the
> hi-start will
> not
> pull off the stake. As extra insurance, you can also loop
> the elastic over
> the
> spike for extra security. I usually do this.
>
> If you start small, say 15' of elastic and 50' of line it
> might feel a lot
> easier to control, and the launch will be lower and the
> energy smaller.
> Again, this is just an assisted hand throw. We will use
> this length
> combination for this discussion. Remember that I am
> assuming your plane
> is well balanced and trimmed and that you can reliably hand
> throw it and
> control that hand throw from your radio. (If you are not a
> master of the
> hand
> throw, put this down and go work on that!)
>
> If your plane is flying well from a hand launch and your tow
> hook is a
> little in front of the CG then I am going to suggest that
> you launch with
> all
> controls at neutral trim, or wherever the plane flies best
> from the hand
> throw. Remember you don't use the elevator to take the
> plane up, the lift
> of the wings will do that. In fact, as we will discuss
> later, if you have
> problems with pop-offs, you can put in 3-4 clicks of down
> elevator to slow
> down the rotation of the plane on the initial launch. Just
> don't forget to
> take it out once you are off the hi-start.
>
> Video example of a hand launch
> www.youtube.com/watch?v=ixwur8lakBM&feature=related
>
>
> If you get your wings out of level on the launch, the plane
> will tend to go
> right or left when you throw it, just like a bad hand throw.
> Use the rudder
> to get it back to center and work on getting a level throw.
>
> It is easy to control the launch force of a hi-start by how
> far back we pull
> it, which will determine the stretch on the elastic and the
> energy of the
> pull Do exactly what you would do on a hand throw.
> Basically flat firm
> throw
> with level wings. The hi-start will continue the pull to
> accelerate the
> plane
> giving the equivalent of a strong hand throw. However as
> the hi-start will
> pull it faster than a hand throw, it will start to climb.
> This is what we
> want.
>
>
> TIME TO LAUNCH
>
> Be sure your receiver and radio are turned on. Complete
> your range check
> and make sure all surfaces are moving in the right
> direction. Now you can
> hook the line to your plane's tow hook and pull back a
> distance equal to the
> length of the elastic, 15 feet in our example. You should
> feel a pull on
> the line, but should have no trouble holding the plane in
> one hand. I like
> to
> grip my plane under the wings and hold it with the wings
> over my head.
>
> Now, check to make sure all of your controls are working
> again. If
> necessary, use your mouth to move the sticks and see that
> everything is
> working. Check the trims on your radio to make sure you
> have not bumped
> them out of place. Do this on EVERY launch ... forever!
>
> Stand firm, don't walk or run with it, and just give it a
> straight. firm,
> flat throw, controls at neutral just like a hand throw. Get
> your hands to
> the controls on the radio ready to guide the plane, but
> don't over control
> it.
> The plane should go out just like a hand launch, only with
> more speed.
> It should naturally climb a little. It should just fly off
> the end of the
> line. Let it glide out and drift down naturally, just as you
> would on a hand
> throw, just further. Be sure you have enough space in front
> of the
> launch to allow it to do this. You don't want to have to
> turn on you first
> hi-start to avoid hitting things.
>
> You just completed your first hi-start launch.
>
> How did that go? If it went left or right, you tipped the
> wings when you
> threw it or your plane is not trimmed to fly straight. Work
> on it at this
> length until you go out level and true every time.
>
> Build up the strength of the pull over several launches.
> Pull back one
> length of the elastic. Launch from this until you are
> comfortable. Then
> pull it back 1 1/2 lengths of the elastic. Then try it at
> twice the length
> of the
> elastic. Make sure you are going out straight and level.
> For a 15 foot
> piece of elastic that would be a 30 foot pull.
>
> Then slide another 15-20 feet of tubing into the working
> area of the
> hi-start and add another 50 feet of line. You are now in
> up-start range
> with 25-40 feet of tubing and 100 feet of line. The plane
> will launch
> higher with this arrangement. You change nothing, let the
> hi-start do the
> work. Just don't forget to get the plane a strong push/throw
> as you release
> it. Don't just let go.
>
> Keep adding elastic in whatever increments you like till you
> get to the full
> length. Add 3-5 times as much line as elastic till you add
> it all back.
> Again a typical full size hi-start is 60 to 100 feet of
> elastic 250-400 feet
> of line.
>
> How far back you want to pull depends on the make and
> diameter of the tubing
> on your hi-start. If this is a commercial hi-start, read
> the makers
> recommendations and follow them. In general, with 1/4 -5/16
> OD latex
> tubing, pulling back two to three times the length of the
> tubing should be
> plenty for your 2 meter plane and should not over stress the
> tubing. If you
> are
> using bungee cord you will likely not be able to pull back
> that far as the
> cloth
> covering constrains it and bungee is typically much stronger
> than the latex
> tubing.
>
> If you are using heavier tubing such as 3/8", 7/16" or 1/2",
> a pull of 1
> 1/2 times the tubing length may be all you would want to do
> with a 2 meter
> plane. My hi-start rubber is 3/8" and I only pull back about
> 1 to 1 1/2
> times the length of the tubing to launch my 2 meter planes.
> At that pull I
> can barely
> hold the plane. I measured it once at 14 pounds of pull
> which is stronger
> than needed for a Spirit, for example. If you feel like
> measuring, a pull
> of 3-5 times your model's weight is a good target, or 6-10
> pounds for the
> typical 2 meter starter plane. I have launched my Spirit at
> up to 14 pounds
> of pull, as measured with a fisherman's scale.
>
> Pop-Offs:
>
> A pop-off occurs when the plane rotates so much during the
> launch that it
> releases the line early and "pops off" the line. This can
> happen anywhere
> but I have usually seen it within the first 150 feet of the
> launch. Pop
> offs can be
> tricky to control. The plane may fly up at an extreme angle
> then stall and
> want to dive for the ground. More often it will pop off and
> go into a loop
> to the rear, behind you. I have found that most of the
> time, if this
> happens, you are best served to just help the plane finish
> the loop rather
> than
> trying to prevent it. Fighting the loop often takes so much
> energy out of
> the plane that it will stall and you are fighting to keep it
> from crashing
> to
> the ground.
>
>
> If the plane starts popping off too soon, try putting a
> click or two of down elevator on the trim before you launch.
> Also make sure
> your tow hook is in FRONT of the CG. About 1/4-1/2 inch is
> enough. The
> likelihood of a pop off will increase with the power of the
> launch due to
> the rotation of the plane from level to climb, so let's get
> it under control
> early. That is why we build up slowly.
>
> As the pull gets stronger, the plane will fly out faster and
> the lift of the
> wings will take it higher naturally. No need to throw it
> up, it will go up
> on its own. You can launch the plane at a more elevated
> angle as you become more comfortable with the hi-start and
> get to know how your
> plane launches.
> Up to a 45 degree angle works well. Just remember that the
> steeper the
> angel the more important the throw. Don't just let go, give
> it a
> good push.
>
> I have over 500 launches with my Spirit, Sagitta and Legend.
> I launch at 20
> to 45 degree up angle with neutral controls and the forward
> tow hook
> position. My planes climb beautifully and I don't give up
> much to the winch,
> if anything.
>
> Using my smaller launcher (25' tubing and 100' line) I get
> 100+ feet
> launches depending on the wind, without a zoom at the end.
> With the larger hi-start (100' 3.8" tubing and 400' line)
> I estimate I go
> up 350-500 foot launches, depending on the wind, and can
> zoom off of the end
> to gain more height if I want.
>
> I was afraid of the hi-start but now I really enjoy it. If
> you have someone
> to coach you through the first few launches you will be
> fine. If you don't,
> try this method.
>
>
> The angle method for placing the tow hook
> www.rcgroups.com/forums/showpost.php?p=7107908&postcount=15
>
> Here is another informational post for those who like more
> technical detail
> The Physics of Hi-Starts
>
www.charlesriverrc.org/articles/design/thingywilliamson_histartphysics.htm
>
> Sailplanes are Wonderful!
> www.rchangout.com/forums/showthread.php?t=5356
>
> If you are new glider pilot, this is a great resource:
> forums.flyesl.com/topic.asp?TOPIC_ID=224
>
> Video of 4M glider launch - Throw is bad, but he
> gets it into the air.
> www.youtube.com/watch?v=T-sYXc9gbUE
