FSK Leonardo Build & Flight report
12-06-2004, 03:09 PM
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FSK Leonardo Build & Flight report
Last week I picked up the FSK [link=http://www.hobby-lobby.com/leonardo.htm]Leonardo [/link] from the LHS. I had seen the flight video and equipment setup at Hobby-Lobby, and it looked like I had almost everything I needed to complete this flyer. Since I had flown an FSK low wing slow flyer before, I knew what sort of materials to expect from this mfg.
This is a rubber band conversion from [link=http://www.flyingstyrokit.cz/]Flying Styro Kits[/link]. As the company name implies, these folks use styro for just about everything, however the components have a nice, smooth finish. They do a great job with molded in panel lines and rivet heads even on the wings - this plane looks great after detailing with a silver sharpie! Everything that came in the box that looked like it would fly on the plane, including the 3-blade prop and spinner, weighed 3.5oz. This is less any battery, electronics, motor or additions.
I am using Cirrus 6.5 servos, GWS ICS-100 ESC, GWS 5.86:1 IPS drive system w/heat sink, and [link=http://www.sheldonshobbies.com/listing/rcl.html]PolyQuest[/link] 600mah 2-cell Lipo battery. The plane includes the FSK 3-blade 9x7 prop with hub adapter for GWS drives. This prop looks great on the plane and gives it the bush plane look I had hoped for, but it flies terribly on this prop, as will be discussed later.
Starting out - the manual is pretty lacking and you have a lot of blanks to fill in. This should be no problem for an experienced builder.
The fuselage comes pretty much ready except for horizontal stab. It has a nice two tone paint scheme, and includes a precut cockpit canopy and prepainted/precut cowl. As mentioned it also has molded in panel lines and rivet heads. It comes with a wood servo tray, landing gear mount, and a wood fuse former already in place. I had to slightly widen the opening in the servo tray to accommodate the Cirrus 6.5's. A very sturdy wood mount for a GWS IPS gear drive is already installed with proper thrust angles, leaving you to slide (ok, wiggle) on the GWS drive system to complete motor mounting. The vertical tail is molded in, shaped very nicely, and interestingly - is also hollow.
One very important/offbeat note about completing this flyer: The cockpit canopy is what attaches the wing to the plane. The canopy gets glued on to the fuse, then the wing gets glued on to the canopy. The canopy is molded to fit the fuse, and to provide proper wing dihedral. But once it is all in place, none of it is coming off. That means all of your electronics and servos should be firmly in place and ready for use, having been well tested and adjusted as required, before you pass the point of no return, which is attaching the wing & cockpit canopy. Also bear in mind that you shouldn't plan on getting any equipment out of this pane except the battery & motor, until it is retired.
I briefly thought about removable wing mounting options, but nothing simple stood out. Be sure your canopy is well glued on to the fuse, and is adjusted appropriately before drying to provide a level mounting surface for the wing.
Since the wing is held on in such a permanent fashion, I could not recommend this plane for beginners. One good shot and you'll rip the wing & canopy off, with some fuse. The wing is supported by what I would call 'semi-structural' (ie - leave them off at your peril) balsa struts. These are also permanently attached to wing & fuse with epoxy.
The slot in the fuse for the horiz. stab needed some trimming with an exacto to get the horizontal stab level and ready for glue. The rudder is prehinged, but when installing you need to insure it gets glued firmly to one side, inside of the hollow vertical tail. Don't pinch the tail together to hold the hinges in, but instead wedge something in there temporarily to push the hinges against the apropriate side of the tail. The rudder also needs to be notched to clear the elevator.
The kit includes some nice & light, quality foam wheels. Previous FSK planes used wheels glued together from two light plastic halves. This was detailed in the build sheet for this plane, but fortunately they are providing better wheels now. The tail wheel is non- steerable. The landing gear is prebent and just slips into a rubber holder which is already glued in the fuse, like a lot of other FSK kits. This is a solid, yet forgiving attachment method. I chose to add a v-shaped wire cross bar to the prebent gear to stiffen it while still providing some suspension. With a 9" prop, you do not have a lot of ground clearance, and this keeps the gear from sagging.
Hobby-Lobby suggests that you use a 120mah 7.2v Nicad in the shape of a 9v battery. I could not understand this battery suggestion until I saw how small the access would be to get to the battery. Battery access is through a SMALL hatch you cut in the top of the wing. Mine is latched with a bit of thin refrigerator magnet material.
The PolyQuest 600mah 2-cell lipo I am using is the same width & depth of a 9v battery, just a little taller - and this is not a problem at all. It is also lighter than the suggested NiCd, weighing in at only 1.2oz. This battery goes in and out of the small hatch with no problems. The battery is located pretty much at CG, and is just dropped in the plane between two fuse formers; mine is held with a very small dab of velcro. Keep in mind the hatch opening is small - about 1.75 x 2.00 inches, so plan all connections and access accordingly, and before you glue the wing on! If you have very large fingers, or if you want to fly a larger battery, you may want to add a charge jack and on/off switch to this plane, and forget about accessing the battery.
There is room for a larger battery in the fuse at the suggested location, but it would not be possbile to remove it through the hatch. Enlarging the hatch risks the structural integrity of the wing, as the hatch is cut in the center of the wing at the glue seam. The CG of this plane is so sensitive to even small weight shifts, that I would not recommend using any other battery location than the mfg suggested one. For example there is a huge cavity just behind the firewall, and a larger hatch could be cut here, but it would require a large amount of tail weight to offset.
FLIGHTS:
The first flight was super sketchy. I had eyeballed the control surface throws to suit me, and they were waaaay too much. Add to this a severe nose heavy condition and the outstanding torque from the prop, and it was a handful to bring back around for a landing - like flying a P-51. I dialed the EPA on the radio down to only 45% left and about 58% right - and took off again. This time was better, but the plane was still very nose heavy. Power off glide was like a rock falling from the sky. I had to keep the speed up to keep it level, and I needed 100% up trim for level flight.
The mfg recommends 35-45mm as the CG range, Without doing anything extra to balance the plane, I was at 35mm. Turns out this is too nose heavy. I went home and taped 7.5 grams of lead to the tail to balance it at 41mm. This proved to be a much better CG location for this plane. At 41mm the power off glide is perfect, and it needs very little up trim to fly level at half throttle. But now I still had one problem left to solve with this plane...
During these first 6 or 7 test flights, the plane was still very sensitive to left input, even with the EPA at 45% and me on a 75% low rate of that AND using a negative EXP setting! So after these trim flights, tired of playing with end points and EXP, I was really bummed out about this plane's bad tendency to wing over at the slightest left input. It was just too sensitive to left input and had to be horsed around in a right turn. I knew I had to try a new prop to reduce the torque....
So I got out the scale and started comparing... The FSK 3-blade 9x7 prop with spinner weighs about 21 grams. The GWS 9x7 2-blade with cut-down spinner weighs about 7.5 grams. Easy decision. I bolted on the GWS prop and I took the 7.5 grams of tail weight out, replacing it with 1.3 grams to keep my CG at 41mm . By switching props, I had just reduced overall plane weight by about 19.5 grams, or .7 ounces - and a lot of that came out of the swingin prop.
My hopes high - I headed back to the baseball diamond at the nearby park... to find out that I now have a great flyer. This is much more what I had hoped for. It is very slow when asked to be. It now turns left/right gracefully and with no bad tendencies. Landings are greasy, and touch & goes a joy. Now if only GWS would make props in something besides day-glo orange :-) I get tired of blackening or browning them with sharpie pens.
I estimate an easy 35 min flight time if just tooling around in a scale fashion, pulling about 1 amp. I use the timed flight method for safe Li-Po use with my cheap ESC's, so I have my 'casual mode' flight timer set for 25 mins, which is plenty of flying time between charges with this little guy and a nice margin of safety.
So here are my humble conclusions: The FSK Leonardo is a great flyer when built as designed, except use a GWS 9x7 2-blade prop. CG seems great around 41mm. With a little extra detail work, it looks very, very nice & semi scale. It should not be built by a first timer, nor is it designed to withstand any type of crash. A computer radio is highly desired, as accessing the servo arms for adjustments - post build - is impossible. The included 3-blade prop should only be used for display purposes :-)
Mods I made:
I epoxied some small wood squares inside the fuse at the motor area to allow me to attach the cowl with screws. I used a GWS 9x7 2-blade prop to reduce prop torque. I cut the cowl cooling vent out under the prop shaft opening - this exposes the motor heat sink directly to airflow. I epoxied some thin refrigerator magnet material for the hatch latch. I used Z-bends on both ends of the control rods since this was going to be a permanent install. I added (wire wrap & silver solder) a V-shaped wire cross bar to the landing gear & painted the gear red. I used some small red hub looking button retainers for the wheels. I detailed panel lines & rivets, and touched up the silver paint job with a silver sharpie. I painted the wing tips with a 'Real Red' acrylic pen, and safety stripes on the 3-blade prop (for display) with a 'Lemon Yellow' acrylic pen. I added some old leftover decals for hatch doors, cowl vents & screens, & door handles. I did not use any of the included kit decals, as they are mainly advertisements for FSK. I am on the lookout for a lightweight 3-blade prop - 21 grams is a joke.
One thing not detailed in the manual that could leave you scratching your head: Use large z-bends where the pushrods exit the pushrod housing inside the fuse, to align the pushrods with the holes in servo arms - as they will otherwise be aligned with the servo output shafts :-) Position the bend so you leave enough room for the rod to move freely in both directions without getting stopped by the pushrod housing or the servo case.
Check back here shortly for links to pics. Thanks!
This is a rubber band conversion from [link=http://www.flyingstyrokit.cz/]Flying Styro Kits[/link]. As the company name implies, these folks use styro for just about everything, however the components have a nice, smooth finish. They do a great job with molded in panel lines and rivet heads even on the wings - this plane looks great after detailing with a silver sharpie! Everything that came in the box that looked like it would fly on the plane, including the 3-blade prop and spinner, weighed 3.5oz. This is less any battery, electronics, motor or additions.
I am using Cirrus 6.5 servos, GWS ICS-100 ESC, GWS 5.86:1 IPS drive system w/heat sink, and [link=http://www.sheldonshobbies.com/listing/rcl.html]PolyQuest[/link] 600mah 2-cell Lipo battery. The plane includes the FSK 3-blade 9x7 prop with hub adapter for GWS drives. This prop looks great on the plane and gives it the bush plane look I had hoped for, but it flies terribly on this prop, as will be discussed later.
Starting out - the manual is pretty lacking and you have a lot of blanks to fill in. This should be no problem for an experienced builder.
The fuselage comes pretty much ready except for horizontal stab. It has a nice two tone paint scheme, and includes a precut cockpit canopy and prepainted/precut cowl. As mentioned it also has molded in panel lines and rivet heads. It comes with a wood servo tray, landing gear mount, and a wood fuse former already in place. I had to slightly widen the opening in the servo tray to accommodate the Cirrus 6.5's. A very sturdy wood mount for a GWS IPS gear drive is already installed with proper thrust angles, leaving you to slide (ok, wiggle) on the GWS drive system to complete motor mounting. The vertical tail is molded in, shaped very nicely, and interestingly - is also hollow.
One very important/offbeat note about completing this flyer: The cockpit canopy is what attaches the wing to the plane. The canopy gets glued on to the fuse, then the wing gets glued on to the canopy. The canopy is molded to fit the fuse, and to provide proper wing dihedral. But once it is all in place, none of it is coming off. That means all of your electronics and servos should be firmly in place and ready for use, having been well tested and adjusted as required, before you pass the point of no return, which is attaching the wing & cockpit canopy. Also bear in mind that you shouldn't plan on getting any equipment out of this pane except the battery & motor, until it is retired.
I briefly thought about removable wing mounting options, but nothing simple stood out. Be sure your canopy is well glued on to the fuse, and is adjusted appropriately before drying to provide a level mounting surface for the wing.
Since the wing is held on in such a permanent fashion, I could not recommend this plane for beginners. One good shot and you'll rip the wing & canopy off, with some fuse. The wing is supported by what I would call 'semi-structural' (ie - leave them off at your peril) balsa struts. These are also permanently attached to wing & fuse with epoxy.
The slot in the fuse for the horiz. stab needed some trimming with an exacto to get the horizontal stab level and ready for glue. The rudder is prehinged, but when installing you need to insure it gets glued firmly to one side, inside of the hollow vertical tail. Don't pinch the tail together to hold the hinges in, but instead wedge something in there temporarily to push the hinges against the apropriate side of the tail. The rudder also needs to be notched to clear the elevator.
The kit includes some nice & light, quality foam wheels. Previous FSK planes used wheels glued together from two light plastic halves. This was detailed in the build sheet for this plane, but fortunately they are providing better wheels now. The tail wheel is non- steerable. The landing gear is prebent and just slips into a rubber holder which is already glued in the fuse, like a lot of other FSK kits. This is a solid, yet forgiving attachment method. I chose to add a v-shaped wire cross bar to the prebent gear to stiffen it while still providing some suspension. With a 9" prop, you do not have a lot of ground clearance, and this keeps the gear from sagging.
Hobby-Lobby suggests that you use a 120mah 7.2v Nicad in the shape of a 9v battery. I could not understand this battery suggestion until I saw how small the access would be to get to the battery. Battery access is through a SMALL hatch you cut in the top of the wing. Mine is latched with a bit of thin refrigerator magnet material.
The PolyQuest 600mah 2-cell lipo I am using is the same width & depth of a 9v battery, just a little taller - and this is not a problem at all. It is also lighter than the suggested NiCd, weighing in at only 1.2oz. This battery goes in and out of the small hatch with no problems. The battery is located pretty much at CG, and is just dropped in the plane between two fuse formers; mine is held with a very small dab of velcro. Keep in mind the hatch opening is small - about 1.75 x 2.00 inches, so plan all connections and access accordingly, and before you glue the wing on! If you have very large fingers, or if you want to fly a larger battery, you may want to add a charge jack and on/off switch to this plane, and forget about accessing the battery.
There is room for a larger battery in the fuse at the suggested location, but it would not be possbile to remove it through the hatch. Enlarging the hatch risks the structural integrity of the wing, as the hatch is cut in the center of the wing at the glue seam. The CG of this plane is so sensitive to even small weight shifts, that I would not recommend using any other battery location than the mfg suggested one. For example there is a huge cavity just behind the firewall, and a larger hatch could be cut here, but it would require a large amount of tail weight to offset.
FLIGHTS:
The first flight was super sketchy. I had eyeballed the control surface throws to suit me, and they were waaaay too much. Add to this a severe nose heavy condition and the outstanding torque from the prop, and it was a handful to bring back around for a landing - like flying a P-51. I dialed the EPA on the radio down to only 45% left and about 58% right - and took off again. This time was better, but the plane was still very nose heavy. Power off glide was like a rock falling from the sky. I had to keep the speed up to keep it level, and I needed 100% up trim for level flight.
The mfg recommends 35-45mm as the CG range, Without doing anything extra to balance the plane, I was at 35mm. Turns out this is too nose heavy. I went home and taped 7.5 grams of lead to the tail to balance it at 41mm. This proved to be a much better CG location for this plane. At 41mm the power off glide is perfect, and it needs very little up trim to fly level at half throttle. But now I still had one problem left to solve with this plane...
During these first 6 or 7 test flights, the plane was still very sensitive to left input, even with the EPA at 45% and me on a 75% low rate of that AND using a negative EXP setting! So after these trim flights, tired of playing with end points and EXP, I was really bummed out about this plane's bad tendency to wing over at the slightest left input. It was just too sensitive to left input and had to be horsed around in a right turn. I knew I had to try a new prop to reduce the torque....
So I got out the scale and started comparing... The FSK 3-blade 9x7 prop with spinner weighs about 21 grams. The GWS 9x7 2-blade with cut-down spinner weighs about 7.5 grams. Easy decision. I bolted on the GWS prop and I took the 7.5 grams of tail weight out, replacing it with 1.3 grams to keep my CG at 41mm . By switching props, I had just reduced overall plane weight by about 19.5 grams, or .7 ounces - and a lot of that came out of the swingin prop.
My hopes high - I headed back to the baseball diamond at the nearby park... to find out that I now have a great flyer. This is much more what I had hoped for. It is very slow when asked to be. It now turns left/right gracefully and with no bad tendencies. Landings are greasy, and touch & goes a joy. Now if only GWS would make props in something besides day-glo orange :-) I get tired of blackening or browning them with sharpie pens.
I estimate an easy 35 min flight time if just tooling around in a scale fashion, pulling about 1 amp. I use the timed flight method for safe Li-Po use with my cheap ESC's, so I have my 'casual mode' flight timer set for 25 mins, which is plenty of flying time between charges with this little guy and a nice margin of safety.
So here are my humble conclusions: The FSK Leonardo is a great flyer when built as designed, except use a GWS 9x7 2-blade prop. CG seems great around 41mm. With a little extra detail work, it looks very, very nice & semi scale. It should not be built by a first timer, nor is it designed to withstand any type of crash. A computer radio is highly desired, as accessing the servo arms for adjustments - post build - is impossible. The included 3-blade prop should only be used for display purposes :-)
Mods I made:
I epoxied some small wood squares inside the fuse at the motor area to allow me to attach the cowl with screws. I used a GWS 9x7 2-blade prop to reduce prop torque. I cut the cowl cooling vent out under the prop shaft opening - this exposes the motor heat sink directly to airflow. I epoxied some thin refrigerator magnet material for the hatch latch. I used Z-bends on both ends of the control rods since this was going to be a permanent install. I added (wire wrap & silver solder) a V-shaped wire cross bar to the landing gear & painted the gear red. I used some small red hub looking button retainers for the wheels. I detailed panel lines & rivets, and touched up the silver paint job with a silver sharpie. I painted the wing tips with a 'Real Red' acrylic pen, and safety stripes on the 3-blade prop (for display) with a 'Lemon Yellow' acrylic pen. I added some old leftover decals for hatch doors, cowl vents & screens, & door handles. I did not use any of the included kit decals, as they are mainly advertisements for FSK. I am on the lookout for a lightweight 3-blade prop - 21 grams is a joke.
One thing not detailed in the manual that could leave you scratching your head: Use large z-bends where the pushrods exit the pushrod housing inside the fuse, to align the pushrods with the holes in servo arms - as they will otherwise be aligned with the servo output shafts :-) Position the bend so you leave enough room for the rod to move freely in both directions without getting stopped by the pushrod housing or the servo case.
Check back here shortly for links to pics. Thanks!
06-26-2005, 04:47 PM
#2
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RE: FSK Leonardo Build & Flight report
Here's an update to my Leonardo setup, and the promised pictures.
I am now flying the Leonardo with a GWS IPS '1' Drive, which is 4.1:1, and 8 x 6 GWS Hyper Drive prop. I am also testing the APC 8 x 4.3 SF prop. The reason for the change in gearing was that the 9" prop did not allow for proper clearance on landing. The margin for any under-rotation error in the flare was zero. So I reduced the gear ratio to turn an 8" prop faster. This is a nice, inexpensive power setup for this plane. Climbout is great, and cruise is about half throttle.
I have done bench testing with the motor and gearing, and find that the GWS HD prop works far better than the GWS EP prop of the same size & pitch. The APC 8 x 4.3 gives more RPM and thrust, at a higher efficiency, but I have yet to fly it to see if there is enough forward speed. A really efficient prop is the Graupner 8 x 4 'Slim Prop' - however it is too heavy to justify using on this light plane.
These pics were taken today - I probably only have 40-50 flights on this plane, since it requires dead calm conditions to enjoy.
Note that some detailing was done with a silver sharpie after construction, and some small decals added - which are not part of the kit.
Click the pictures for a larger image !!!
[link=http://www.airsoftsupply.com/rc/leonardo/leo_1.jpg]
[/link]
[link=http://www.airsoftsupply.com/rc/leonardo/leo_2.jpg]
[/link]
[link=http://www.airsoftsupply.com/rc/leonardo/leo_3.jpg]
[/link]
[link=http://www.airsoftsupply.com/rc/leonardo/leo_4.jpg]
[/link]
I am now flying the Leonardo with a GWS IPS '1' Drive, which is 4.1:1, and 8 x 6 GWS Hyper Drive prop. I am also testing the APC 8 x 4.3 SF prop. The reason for the change in gearing was that the 9" prop did not allow for proper clearance on landing. The margin for any under-rotation error in the flare was zero. So I reduced the gear ratio to turn an 8" prop faster. This is a nice, inexpensive power setup for this plane. Climbout is great, and cruise is about half throttle.
I have done bench testing with the motor and gearing, and find that the GWS HD prop works far better than the GWS EP prop of the same size & pitch. The APC 8 x 4.3 gives more RPM and thrust, at a higher efficiency, but I have yet to fly it to see if there is enough forward speed. A really efficient prop is the Graupner 8 x 4 'Slim Prop' - however it is too heavy to justify using on this light plane.
These pics were taken today - I probably only have 40-50 flights on this plane, since it requires dead calm conditions to enjoy.
Note that some detailing was done with a silver sharpie after construction, and some small decals added - which are not part of the kit.
Click the pictures for a larger image !!!
[link=http://www.airsoftsupply.com/rc/leonardo/leo_1.jpg]
[/link][link=http://www.airsoftsupply.com/rc/leonardo/leo_2.jpg]
[/link][link=http://www.airsoftsupply.com/rc/leonardo/leo_3.jpg]
[/link][link=http://www.airsoftsupply.com/rc/leonardo/leo_4.jpg]
[/link]
08-14-2005, 10:00 AM
#3
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Join Date: Nov 2004
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RE: FSK Leonardo Build & Flight report
Somehow the links to pictures in the last message got jammed up over time - so here are links to pics that hopefully will remain here longterm.
http://www.airsoftsupply.com/rc/leonardo/leo_1.jpg
http://www.airsoftsupply.com/rc/leonardo/leo_2.jpg
http://www.airsoftsupply.com/rc/leonardo/leo_3.jpg
http://www.airsoftsupply.com/rc/leonardo/leo_4.jpg
http://www.airsoftsupply.com/rc/leonardo/leo_1.jpg
http://www.airsoftsupply.com/rc/leonardo/leo_2.jpg
http://www.airsoftsupply.com/rc/leonardo/leo_3.jpg
http://www.airsoftsupply.com/rc/leonardo/leo_4.jpg
