Post by wildflyer on Aug 26, 2023 15:20:07 GMT -6
LEARNING TO USE A HI-START
by Ed Anderson in july 2006 Because of it's age some of the links might not work (Dave) I removed some that did not work.
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.
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 someo ne 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 inital 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 whereever 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.
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 450 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.
Sailplanes are Wonderful!
www.rchangout.com/forums/showthread.php?t=5356
That plane was made to fly. Fly it!
__________________
Long Island Silent Flyers
www.lisf.org
Eastern Soaring League
www.flyesl.org
by Ed Anderson in july 2006 Because of it's age some of the links might not work (Dave) I removed some that did not work.
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.
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 someo ne 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 inital 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 whereever 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.
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 450 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.
Sailplanes are Wonderful!
www.rchangout.com/forums/showthread.php?t=5356
That plane was made to fly. Fly it!
__________________
Long Island Silent Flyers
www.lisf.org
Eastern Soaring League
www.flyesl.org