gavoss
Jan 30, 2003, 01:00 AM
<blockquote>In November's column, I promised an update on the Great Planes Spirit Elite (SE). The primary goal was to make the plane lighter, at least a half of a pound lighter to be exact! In addition, we wanted it to launch higher, make it easier to see, and above all, not "break the bank."</blockquote>
<p><big>Spirit Elite Modifications</p></big>
<blockquote>I have done a number of reviews of Great Planes' products and I'm continually amazed at the quality products they produce. While this isn't a kit review per-se', my intentions are to show you how to transform a good plane into a great one.</blockquote>
<blockquote>In my opinion, the Spirit Elite ARF, with a street price of $130, is a real value. If you have checked the cost of a fiberglass fuselage lately, you know they sell for anywhere between $50 to $150, depending on the size and quality of finish. To get the quality of finish of the SE, which has a gel-coated white epoxy-fiberglass fuselage, you would expect to pay close to $100 for the fuselage alone. That means you are paying only $30 for a set of assembled and covered flying surfaces and all the hardware!</blockquote>
<blockquote>My flying buddy, Ken Stone, couldn't resist purchasing the SE. Ken ordered the kit before they were available, so he had to wait about a month from the time he placed the order until the time he received the kit. Ken was ecstatic when the kit arrived, but after perusing through what was provided in the kit, there were a few areas of concern. Ken started picking my brain to see what we could do to improve the kit.</blockquote>
<blockquote>The instruction manual states the SE flying weight would be 46 to 48 ounces. This weight is totally unacceptable for a 2-Meter thermal sailplane, even with nearly a 650 square inch wing. The second problem is that both the top and bottom of the wing are white, which makes the plane difficult to see at high altitudes.</blockquote>
<div align="center">
<table border="1" cellpaddin="4" cellspacing="0" width="80%" bgcolor="#E6E6E6">
<tr>
<td width="100%" align="center"><a href="/articles/liftzone/2003/jan/thermal/se_diamonds.jpg"><img src="http://static.rcgroups.com/articles/liftzone/2003/jan/thermal/se_diamonds_t.jpg" border="2"></a> </td>
</tr>
<tr>
<td width="100%" align="left">Ken used MonoKote Trim Solvent to install the charcoal gray diamonds on the bottom of the Spirit Elite. It took several hours to determine the correct size of the diamonds. Once the size was determined, it only took about two hours to cut out and install the diamonds. Whether you choose diamonds or another shape, I strongly recommend some form of contrast on the bottom of the wing.</td>
</tr>
</table>
</div>
<blockquote>There were two ways to change the solid white bottom of the wing, either recover it in a dark color, or apply enough trim to make the plane easier to see. Since the object of this exercise is to do as little as possible, for as little as possible, recovering the bottom of the wing was ruled out. However, Ken came up with an easy to see and install solution. He put a series of diamonds on the bottom of the wing. Ken chose charcoal MonoKote, and instead of ironing it on, he used MonoKote Trim Solvent to apply the diamonds. We hadn't anticipated the effect, but at low altitude, you can see the diamonds. Slightly higher, at say 300 to 500 feet, the bottom of the wing looks like it has stripes on it. Above launch altitude, roughly at 600 feet, the bottom of the wing looks black.</blockquote>
<blockquote>We then took a serious look at how we could bring the ready-to-fly (RTF) weight down to a maximum of 40 ounces or less if possible. The SE kit comes with 1/16" music wire pushrods for the elevator and rudder. The rods themselves weigh nearly an ounce each. There is roughly a 1:3 balance ratio on most sailplanes, the SE included. Therefore, if we add an ounce to the tail of the plane, we'll need three ounces in the nose to return the CG back to its correct location. Likewise, if we remove an ounce from the tail, we can remove three ounces from the nose. All we had to do was find a lighter, no, make that much lighter pushrod system for the elevator and rudder, so enter <a href="http://www.cstsales.com">Composite Structures Technology (CST)</a>.</blockquote>
<blockquote>CST has a series of carbon fiber push rods that are encased in a Teflon sleeve. The carbon rods come in .030, .050, .070 inch diameters. Ken used CST P/N T1070, the.070 in diameter size carbon rod for the elevator pushrod. To give you an idea of the diameter of each rod size, a sheet of notebook paper is about .003 in. thick. Ten sheets of notebook paper are equivalent to the small, .030-inch diameter size. If you plan on zoom launching the plane, I recommend the .070 in. diameter, and that is what Ken installed in the SE for the elevator pushrod.</blockquote>
<blockquote>The outer tube of the pushrod system is Teflon; you can't directly glue the tube to the side of the fuselage since virtually nothing sticks to Teflon. To allow the tube to be glued to the insides of the fuselage, wrap the tube with one inch of masking tape every three to four inches. The tape will stick to the Teflon, and with the application of thin or medium CA, the tube will then stick to the fuselage securely.</blockquote>
<blockquote>I installed a set of CST carbon fiber pushrods in an Omega 1.8E a while back and I accidentally dribbled some medium CA into the tube with the carbon rod in place. With other types of pushrod systems, this accident would have ruined the installation. Since the CA didn't stick to the Teflon tube, it attached itself to the carbon rod. I was able to remove the carbon pushrod and simply scraped the CA off the rod, and then I was back in business.</blockquote>
<div align="center">
<table border="1" cellpaddin="4" cellspacing="0" width="80%" bgcolor="#E6E6E6">
<tr>
<td width="100%" align="center"><a href="/articles/liftzone/2003/jan/thermal/se_rudder.jpg"><img src="http://static.rcgroups.com/articles/liftzone/2003/jan/thermal/se_rudder_t.jpg" border="2"></a> </td>
</tr>
<tr>
<td width="100%" align="left">A small 1/16" plywood pull-pull horn us used in place of the kit supplied control horn. By using pull-pull for the rudder and a .070 carbon rod for the elevator pushrod, we were able to save close to eight ounces in the overall weight of the Spirit Elite!</td>
</tr>
</table>
</div>
<blockquote>Ken used a pull-pull actuation system for the rudder. There are a number of pull-pull kits available at your local hobby shop, but most are designed for power plane use and are heavier and stronger than needed for a sailplane. Ken chose to use a simple 1/16" ply control horn on the rudder. For the actual cable, he used "Spider Line" from the local Wal-Mart sporting goods section. Ten-pound test is more than strong enough for rudder actuation. The difference between Spider Line and regular monofilament fishing line is that Spider Line has no stretch, and that particular characteristic is required for pull-pull systems.</blockquote>
<blockquote>Use a blood or <a href="http://highsierrasports.net/fishing_knots.htm#Uni-Knot">Uni-knot</a> at the rudder control horn. A small piece of aluminum tubing in which the cable was attached was then was glued with CA into a threaded coupler at the servo end. Ken also installed 2-56 locknuts to keep the threaded coupler tight against the clevis. The pull-pull system doesn't really need the locknut since there is always a small amount of force being applied to the cable. However, normal pushrod/clevis connections should always have a locknut on them to keep slop in the linkage to a minimum. Speaking of tension, there appears to be many who don't know what the proper tension needs to be for a pull-pull system. The tension only needs to be enough so there is no slop in the system. With anything more than that, you are putting a strain on the servo.</blockquote>
<div align="center">
<table border="1" cellpaddin="4" cellspacing="0" width="80%" bgcolor="#E6E6E6">
<tr>
<td width="100%" align="center"><a href="/articles/liftzone/2003/jan/thermal/se_servo_install.jpg"><img src="http://static.rcgroups.com/articles/liftzone/2003/jan/thermal/se_servo_install_t.jpg" border="2"></a> </td>
</tr>
<tr>
<td width="100%" align="left">Notice the clean, neat installation of the servos. While the elevator servo appears to be difficult to adjust, it needs no adjustment since an enormous amount of time was spent making sure it was correct before the servo was glued in place. The pull-pull rudder system is also visible. Ken certainly exhibits craftsmanship, doesn't he? </td>
</tr>
</table>
</div>
<blockquote>Ken used six Expert SL-300 servos for surface actuation. These servos have nylon gears, weigh just six tenths of an ounce, and have 45 in.oz. of torque. These servos are perfect for the SE. You'll notice in the photo that the elevator servo is on its side, with the servo arm facing the bottom of the fuselage. You'll also notice masking tape, which wraps around the servo and terminates on the upper side, looking at the servo. The reason for this is it allows the elevator pushrod to be a straight line, with no bends to cause friction in the pushrod. Obviously, it takes more time to install this type of set up since there is really no way to service the servo once it's glued into place. What you don't see is a small block of blue foam with a piece of 1/16" balsa sheet epoxied to the top of it. The masking tape on the servo allows the servo to be removed without tearing up the servo or the mounting block. Everything has to be hooked up and functioning perfectly before the servo is epoxied to the block. Ken has close to 100 flights on the SE with no signs of linkage problems.</blockquote>
<blockquote>Ken also added some additional features that allow the SE to fit back into its original box for storage and shipment. The most dramatic modification was to make the tail feathers removable. Ken drilled and tapped the fuselage to keep the weight down. The nylon screws screw directly into the fiberglass. The nylon screws probably weigh about the same as the necessary epoxy that would have been used to install the stab. Finally, Ken replaced the steel wing hold down bolts with counter sunk nylon screws.</blockquote>
<div align="center">
<table border="1" cellpaddin="4" cellspacing="0" width="80%" bgcolor="#E6E6E6">
<tr>
<td width="100%" align="center"><a href="/articles/liftzone/2003/jan/thermal/se.jpg"><img src="http://static.rcgroups.com/articles/liftzone/2003/jan/thermal/se_t.jpg" border="2"></a> </td>
</tr>
<tr>
<td width="100%" align="left">Here is the completed, and much lightened Spirit Elite ARF. From this view, it's difficult to tell that anything special has been done, but at 40 ounces, it's lighter than any Spirit Elite I have seen.</td>
</tr>
</table>
</div>
<blockquote>All these modifications allowed the SE to weigh in at just a hair over 40 ounces. Ken and I were more than pleased with the result. The reduced weight will show the most benefit in early morning flights and on calm or windless days.</blockquote>
<blockquote>There is one other weight reducing modification we haven't arrived at an accurate solution for yet; the wing rod. The kit supplied wing rod is 7mm diameter and weighs about four ounces. If we could find a 7mm carbon wing rod, we are sure we could save an additional two or possibly three ounces! The problem is that 7mm metric carbon rods aren't popular in the US. A 7mm rod is about 0.275 in. diameter. An alternate method would be to use a .250 in. diameter carbon rod and epoxy a 7mm OD aluminum or brass tube on the outside of the carbon rod. This will obviously weigh more than the carbon rod alone, but the result should still save an additional two ounces.</blockquote>
<p><big>Industry News</p></big>
<blockquote>In case you haven't heard, Hitec has acquired all of the assets of Multiplex Modelletchnik GmbH and Multiplex USA. It is still uncertain as to what changes will be made, but preliminary indications are that Hitec and Multiplex will remain separate companies as far as products are concerned. Hopefully, with the aggressive marketing and management style of Hitec, Multiplex prices will go down. One interesting note is that now Hitec produces both positive and negative shift transmitters. It's still unknown if they will change shift modes for either Hitec or Multiplex.</blockquote>
<p><big>Upcoming </p></big>
<blockquote>Next time, I will fill you in on details concerning a Speed 400 thermal coming up in June, and I'll let you know my first impressions of the Tempest from Mark Triebes!</blockquote>
<blockquote>Until next time, build straight and launch high!</blockquote>
<p><big>Spirit Elite Modifications</p></big>
<blockquote>I have done a number of reviews of Great Planes' products and I'm continually amazed at the quality products they produce. While this isn't a kit review per-se', my intentions are to show you how to transform a good plane into a great one.</blockquote>
<blockquote>In my opinion, the Spirit Elite ARF, with a street price of $130, is a real value. If you have checked the cost of a fiberglass fuselage lately, you know they sell for anywhere between $50 to $150, depending on the size and quality of finish. To get the quality of finish of the SE, which has a gel-coated white epoxy-fiberglass fuselage, you would expect to pay close to $100 for the fuselage alone. That means you are paying only $30 for a set of assembled and covered flying surfaces and all the hardware!</blockquote>
<blockquote>My flying buddy, Ken Stone, couldn't resist purchasing the SE. Ken ordered the kit before they were available, so he had to wait about a month from the time he placed the order until the time he received the kit. Ken was ecstatic when the kit arrived, but after perusing through what was provided in the kit, there were a few areas of concern. Ken started picking my brain to see what we could do to improve the kit.</blockquote>
<blockquote>The instruction manual states the SE flying weight would be 46 to 48 ounces. This weight is totally unacceptable for a 2-Meter thermal sailplane, even with nearly a 650 square inch wing. The second problem is that both the top and bottom of the wing are white, which makes the plane difficult to see at high altitudes.</blockquote>
<div align="center">
<table border="1" cellpaddin="4" cellspacing="0" width="80%" bgcolor="#E6E6E6">
<tr>
<td width="100%" align="center"><a href="/articles/liftzone/2003/jan/thermal/se_diamonds.jpg"><img src="http://static.rcgroups.com/articles/liftzone/2003/jan/thermal/se_diamonds_t.jpg" border="2"></a> </td>
</tr>
<tr>
<td width="100%" align="left">Ken used MonoKote Trim Solvent to install the charcoal gray diamonds on the bottom of the Spirit Elite. It took several hours to determine the correct size of the diamonds. Once the size was determined, it only took about two hours to cut out and install the diamonds. Whether you choose diamonds or another shape, I strongly recommend some form of contrast on the bottom of the wing.</td>
</tr>
</table>
</div>
<blockquote>There were two ways to change the solid white bottom of the wing, either recover it in a dark color, or apply enough trim to make the plane easier to see. Since the object of this exercise is to do as little as possible, for as little as possible, recovering the bottom of the wing was ruled out. However, Ken came up with an easy to see and install solution. He put a series of diamonds on the bottom of the wing. Ken chose charcoal MonoKote, and instead of ironing it on, he used MonoKote Trim Solvent to apply the diamonds. We hadn't anticipated the effect, but at low altitude, you can see the diamonds. Slightly higher, at say 300 to 500 feet, the bottom of the wing looks like it has stripes on it. Above launch altitude, roughly at 600 feet, the bottom of the wing looks black.</blockquote>
<blockquote>We then took a serious look at how we could bring the ready-to-fly (RTF) weight down to a maximum of 40 ounces or less if possible. The SE kit comes with 1/16" music wire pushrods for the elevator and rudder. The rods themselves weigh nearly an ounce each. There is roughly a 1:3 balance ratio on most sailplanes, the SE included. Therefore, if we add an ounce to the tail of the plane, we'll need three ounces in the nose to return the CG back to its correct location. Likewise, if we remove an ounce from the tail, we can remove three ounces from the nose. All we had to do was find a lighter, no, make that much lighter pushrod system for the elevator and rudder, so enter <a href="http://www.cstsales.com">Composite Structures Technology (CST)</a>.</blockquote>
<blockquote>CST has a series of carbon fiber push rods that are encased in a Teflon sleeve. The carbon rods come in .030, .050, .070 inch diameters. Ken used CST P/N T1070, the.070 in diameter size carbon rod for the elevator pushrod. To give you an idea of the diameter of each rod size, a sheet of notebook paper is about .003 in. thick. Ten sheets of notebook paper are equivalent to the small, .030-inch diameter size. If you plan on zoom launching the plane, I recommend the .070 in. diameter, and that is what Ken installed in the SE for the elevator pushrod.</blockquote>
<blockquote>The outer tube of the pushrod system is Teflon; you can't directly glue the tube to the side of the fuselage since virtually nothing sticks to Teflon. To allow the tube to be glued to the insides of the fuselage, wrap the tube with one inch of masking tape every three to four inches. The tape will stick to the Teflon, and with the application of thin or medium CA, the tube will then stick to the fuselage securely.</blockquote>
<blockquote>I installed a set of CST carbon fiber pushrods in an Omega 1.8E a while back and I accidentally dribbled some medium CA into the tube with the carbon rod in place. With other types of pushrod systems, this accident would have ruined the installation. Since the CA didn't stick to the Teflon tube, it attached itself to the carbon rod. I was able to remove the carbon pushrod and simply scraped the CA off the rod, and then I was back in business.</blockquote>
<div align="center">
<table border="1" cellpaddin="4" cellspacing="0" width="80%" bgcolor="#E6E6E6">
<tr>
<td width="100%" align="center"><a href="/articles/liftzone/2003/jan/thermal/se_rudder.jpg"><img src="http://static.rcgroups.com/articles/liftzone/2003/jan/thermal/se_rudder_t.jpg" border="2"></a> </td>
</tr>
<tr>
<td width="100%" align="left">A small 1/16" plywood pull-pull horn us used in place of the kit supplied control horn. By using pull-pull for the rudder and a .070 carbon rod for the elevator pushrod, we were able to save close to eight ounces in the overall weight of the Spirit Elite!</td>
</tr>
</table>
</div>
<blockquote>Ken used a pull-pull actuation system for the rudder. There are a number of pull-pull kits available at your local hobby shop, but most are designed for power plane use and are heavier and stronger than needed for a sailplane. Ken chose to use a simple 1/16" ply control horn on the rudder. For the actual cable, he used "Spider Line" from the local Wal-Mart sporting goods section. Ten-pound test is more than strong enough for rudder actuation. The difference between Spider Line and regular monofilament fishing line is that Spider Line has no stretch, and that particular characteristic is required for pull-pull systems.</blockquote>
<blockquote>Use a blood or <a href="http://highsierrasports.net/fishing_knots.htm#Uni-Knot">Uni-knot</a> at the rudder control horn. A small piece of aluminum tubing in which the cable was attached was then was glued with CA into a threaded coupler at the servo end. Ken also installed 2-56 locknuts to keep the threaded coupler tight against the clevis. The pull-pull system doesn't really need the locknut since there is always a small amount of force being applied to the cable. However, normal pushrod/clevis connections should always have a locknut on them to keep slop in the linkage to a minimum. Speaking of tension, there appears to be many who don't know what the proper tension needs to be for a pull-pull system. The tension only needs to be enough so there is no slop in the system. With anything more than that, you are putting a strain on the servo.</blockquote>
<div align="center">
<table border="1" cellpaddin="4" cellspacing="0" width="80%" bgcolor="#E6E6E6">
<tr>
<td width="100%" align="center"><a href="/articles/liftzone/2003/jan/thermal/se_servo_install.jpg"><img src="http://static.rcgroups.com/articles/liftzone/2003/jan/thermal/se_servo_install_t.jpg" border="2"></a> </td>
</tr>
<tr>
<td width="100%" align="left">Notice the clean, neat installation of the servos. While the elevator servo appears to be difficult to adjust, it needs no adjustment since an enormous amount of time was spent making sure it was correct before the servo was glued in place. The pull-pull rudder system is also visible. Ken certainly exhibits craftsmanship, doesn't he? </td>
</tr>
</table>
</div>
<blockquote>Ken used six Expert SL-300 servos for surface actuation. These servos have nylon gears, weigh just six tenths of an ounce, and have 45 in.oz. of torque. These servos are perfect for the SE. You'll notice in the photo that the elevator servo is on its side, with the servo arm facing the bottom of the fuselage. You'll also notice masking tape, which wraps around the servo and terminates on the upper side, looking at the servo. The reason for this is it allows the elevator pushrod to be a straight line, with no bends to cause friction in the pushrod. Obviously, it takes more time to install this type of set up since there is really no way to service the servo once it's glued into place. What you don't see is a small block of blue foam with a piece of 1/16" balsa sheet epoxied to the top of it. The masking tape on the servo allows the servo to be removed without tearing up the servo or the mounting block. Everything has to be hooked up and functioning perfectly before the servo is epoxied to the block. Ken has close to 100 flights on the SE with no signs of linkage problems.</blockquote>
<blockquote>Ken also added some additional features that allow the SE to fit back into its original box for storage and shipment. The most dramatic modification was to make the tail feathers removable. Ken drilled and tapped the fuselage to keep the weight down. The nylon screws screw directly into the fiberglass. The nylon screws probably weigh about the same as the necessary epoxy that would have been used to install the stab. Finally, Ken replaced the steel wing hold down bolts with counter sunk nylon screws.</blockquote>
<div align="center">
<table border="1" cellpaddin="4" cellspacing="0" width="80%" bgcolor="#E6E6E6">
<tr>
<td width="100%" align="center"><a href="/articles/liftzone/2003/jan/thermal/se.jpg"><img src="http://static.rcgroups.com/articles/liftzone/2003/jan/thermal/se_t.jpg" border="2"></a> </td>
</tr>
<tr>
<td width="100%" align="left">Here is the completed, and much lightened Spirit Elite ARF. From this view, it's difficult to tell that anything special has been done, but at 40 ounces, it's lighter than any Spirit Elite I have seen.</td>
</tr>
</table>
</div>
<blockquote>All these modifications allowed the SE to weigh in at just a hair over 40 ounces. Ken and I were more than pleased with the result. The reduced weight will show the most benefit in early morning flights and on calm or windless days.</blockquote>
<blockquote>There is one other weight reducing modification we haven't arrived at an accurate solution for yet; the wing rod. The kit supplied wing rod is 7mm diameter and weighs about four ounces. If we could find a 7mm carbon wing rod, we are sure we could save an additional two or possibly three ounces! The problem is that 7mm metric carbon rods aren't popular in the US. A 7mm rod is about 0.275 in. diameter. An alternate method would be to use a .250 in. diameter carbon rod and epoxy a 7mm OD aluminum or brass tube on the outside of the carbon rod. This will obviously weigh more than the carbon rod alone, but the result should still save an additional two ounces.</blockquote>
<p><big>Industry News</p></big>
<blockquote>In case you haven't heard, Hitec has acquired all of the assets of Multiplex Modelletchnik GmbH and Multiplex USA. It is still uncertain as to what changes will be made, but preliminary indications are that Hitec and Multiplex will remain separate companies as far as products are concerned. Hopefully, with the aggressive marketing and management style of Hitec, Multiplex prices will go down. One interesting note is that now Hitec produces both positive and negative shift transmitters. It's still unknown if they will change shift modes for either Hitec or Multiplex.</blockquote>
<p><big>Upcoming </p></big>
<blockquote>Next time, I will fill you in on details concerning a Speed 400 thermal coming up in June, and I'll let you know my first impressions of the Tempest from Mark Triebes!</blockquote>
<blockquote>Until next time, build straight and launch high!</blockquote>