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My first balsa build - the Gentle Lady!

The Hangar

Fly harder!
Mentor
#1
I can’t believe I’m doing this - I’m starting my first balsa build! I was gifted a gentle lady kit from a relative a little over year ago, and it’s been collecting dust in my shop. A couple months ago I pulled it out and tried to start on the wing, however I was a little overwhelmed and put it away for a while. However @rockyboy has been inspiring me with his awesome builds lately, and I decided to dig it out and give it another go, but this time I decided to look at the instruction booklet. :) This evening I laid out all the parts and found out that I have everything except two parts, which are going to be really easy to cut out, and I have a bit of extra balsa he gave me that will work. I haven’t gone through all the sticks yet, but I got busy fixing some birds for flying tomorrow, however I’ll get that done and possibly start the assembly tomorrow.
image.jpg
 

speedbirdted

Legendary member
#2
Hey, you finally got around to this :p It at least looks like all the important parts are there....

A few things I remember being tricky areas/problems from my build.
  • Don't let the fuselage get twisted. This is exceptionally easy to do with all-sheet fuselages that are long and thin. A good way to mitigate this is by making a bunch of 90 degree right triangles out of foamboard (I'm guessing you have more than enough of that ;)) and then pinning them whatever way you want so that the fuselage sides are held straight and true over top of the plans. Speaking of that, what are you building on? A sheet of 1/2 inch thick insulation board nailed to a door is a great building surface but don't let CA onto the foam; we all know what the result of that is.
  • Be really careful with getting the wing dihedral right. The amount specified in the manual might seem excessive, and I think there's a warning in there saying to add the recommended amount. Well, do it! I skimped on the dihedral on mine by accident and as a result it turns like a container ship. The glide ratio is more than enough with the recommended dihedral, even in hard turns to stay inside a thermal it doesn't get sinky.
  • Keep the tail light, and by extension everything light. The tail boom is long, and the nose short. Do not use epoxy to glue the tail on! I would recommend something like Titebond or PVA both because they are lighter and also one-part so small quantities will cure with more strength. Mine required like 3 or 4 ounces of weight in the nose to balance right which is just ridiculous. The weight on the plans is stated at 27 ounces but keep in mind this is factoring in standard size servos and nicad batteries. An AUW of sub 20 ounces is definitely possible. If I would have paid more attention to tail weight reduction that may have been a goal I achieved :mad:
  • DON'T build the detachable wingtips! Lugging a 2 meter wing around may seem like a major drag, but having your wingtip fail and send the thing into an irrecoverable flatspin is even more of a drag (literally) I have personally seen this happen during a bungee launch which completely destroyed the airplane when it literally piledrove it into the ground.
  • Speaking of the wingtips, the dihedral braces between the inner and outer wingtips seem to be an area of problems for some builders. My kit was very old (I believe the sticker on the box was dated 1981 and the plane was designed in 79 so it was fairly new) and these dihedral braces which sandwich either side on both spars were made of balsa. On one side after a slightly hard landing which touched a wingtip, they cracked. I ended up putting liteply braces over top them cut out to the same shape, because it would have been too much work to clear them out entirely. If your kit has these braces made out of balsa, buy some 1/16 inch liteply, trace the shape, and cut them out of that instead.
  • The hatch also has some problems. The way it's done normally is it has a tongue on the forward edge which slides inside the fuselage and the rear is held down by the wing sitting on top of it. Well, twice now for me, during a launch with lots of pull to get the thing really up there, the wing has slid backwards far enough during the initial climb to eject the hatch. The first time I found the hatch but the second time I didn't and instead just built another one with magnets holding it in and the problem has never happened since.
  • The build manual says to hinge the control surfaces with the covering film. Don't do this. I don't get why anyone does this. It's just so incredibly lazy and stupid. Buy some CA hinges and use that instead. CA hinges catch a lot of flak from people that either don't know how to install them correctly or use them in inappropriate situations. Done right, there is no gap, and very little if any potential for lateral movement of a control surface. At the aero loads that a sailplane experiences, both of these things matter very little anyway.
  • Did you get the little bag of hardware including stuff like control horns and music wire? Mine didn't and I had to supply it myself but you have to be really careful with the control horn sizes. The way the elevator pushrod works is it gets routed through a little hole in the tail. It's actually really cool looking, and very clean aerodynamically BUT the hole in the control horn has to line up exactly with the hole there so the clevis will be able to meet up with it correctly without binding on the edges of the hole. You can move the hole up and down slightly but because of the rear doublers and the fuselage bottom there is not much wiggle room. The Goldberg 1/2A control horns were literally what this was designed in mind with to use and I was lucky to have a few lying around but otherwise Ebay is the answer since I don't think they're manufactured anymore. You also have to use the Goldberg mini clevises - I know the Dubro ones don't fit unless you drill the hole out really far into the fuselage. The Sullivan metal ones probably work, I just haven't tried it.
  • The wing covering is incredibly important to get right. Most RC sailplane wings get their stiffness more from the covering then the actual wing structure - so be careful mostly to shrink it all evenly and not cause warping and apply the edges nicely enough that they won't pull away when shrunk. Remember the dihedral braces I mentioned building out of liteply here? Well, they will also help save the covering a little. Before I added them, the added stress carried by the covering film meant it was constantly causing long thin breakages of the covering parallel to and directly next to the wing rib on top of the dihedral brace which I had to keep patching, and then patch the patches when they also got broken. I would suggest going over all the seams in the covering with an extra layer of clear covering, or if you're doing the wing all one color, just another layer of that color.
  • Speaking of covering. Use transparent stuff on at least the wing. Sailplanes, by nature, go very high. This is really fun, both to make the FAA angry and ride thermals all day :ROFLMAO: But - as you get higher, and farther away, eventually the human eye loses the ability to discern the color of an object that is not either translucent or actively eminating any light, something that solid color films obviously do not do. Arguably this is much more important on really fast planes and ones with roll control, but you should use transparent or translucent covering film. They remain very easy to see no matter how high up you go, plus they just look really cool.
It's 5:30 AM and I really should go to bed now. But I'll probably think of more later...
 
#3
A few things I remember being tricky areas/problems from my build.
Go, Hangar, Go! Read what speedbirdted wrote and memorize it. This is exactly what a new builder needs to know! Every kit has its "Gotchas" and you will avoid them by following in the footsteps of an experienced builder. I listened to Joker's advice when I built the Sunbird glider, my first balsa build in 45 years. It came with horrible build instructions. It turned out lighter than most other Sunbird builds and is my favorite airplane for thermal hunting on warm summer days.
 
#4
Oh dang, if only I had your advice a few years ago. I built my gentle lady all stock (except for adding spoilers, which is really easy, but optional). I too had to add some nose weight, even though I was using those big ol' futaba servos and a battery pack made from 4 AA's. I guess that's not too much weight in the nose. The hatch has fallen off during launch for me too. I had to make my own leading and trailing edges out of balsa since the kit only had enough for the inboard panels. The people at the field seemed impressed though. Maybe its because I'm the only young guy there with an interest in sailplanes.
I'm getting of track. Yeah, speedbirdted has good advice.


by the way, have you considered giving it an electric motor? Just putting it out there...
 

The Hangar

Fly harder!
Mentor
#5
Hey, you finally got around to this :p It at least looks like all the important parts are there....

A few things I remember being tricky areas/problems from my build.
  • Don't let the fuselage get twisted. This is exceptionally easy to do with all-sheet fuselages that are long and thin. A good way to mitigate this is by making a bunch of 90 degree right triangles out of foamboard (I'm guessing you have more than enough of that ;)) and then pinning them whatever way you want so that the fuselage sides are held straight and true over top of the plans. Speaking of that, what are you building on? A sheet of 1/2 inch thick insulation board nailed to a door is a great building surface but don't let CA onto the foam; we all know what the result of that is.
  • Be really careful with getting the wing dihedral right. The amount specified in the manual might seem excessive, and I think there's a warning in there saying to add the recommended amount. Well, do it! I skimped on the dihedral on mine by accident and as a result it turns like a container ship. The glide ratio is more than enough with the recommended dihedral, even in hard turns to stay inside a thermal it doesn't get sinky.
  • Keep the tail light, and by extension everything light. The tail boom is long, and the nose short. Do not use epoxy to glue the tail on! I would recommend something like Titebond or PVA both because they are lighter and also one-part so small quantities will cure with more strength. Mine required like 3 or 4 ounces of weight in the nose to balance right which is just ridiculous. The weight on the plans is stated at 27 ounces but keep in mind this is factoring in standard size servos and nicad batteries. An AUW of sub 20 ounces is definitely possible. If I would have paid more attention to tail weight reduction that may have been a goal I achieved :mad:
  • DON'T build the detachable wingtips! Lugging a 2 meter wing around may seem like a major drag, but having your wingtip fail and send the thing into an irrecoverable flatspin is even more of a drag (literally) I have personally seen this happen during a bungee launch which completely destroyed the airplane when it literally piledrove it into the ground.
  • Speaking of the wingtips, the dihedral braces between the inner and outer wingtips seem to be an area of problems for some builders. My kit was very old (I believe the sticker on the box was dated 1981 and the plane was designed in 79 so it was fairly new) and these dihedral braces which sandwich either side on both spars were made of balsa. On one side after a slightly hard landing which touched a wingtip, they cracked. I ended up putting liteply braces over top them cut out to the same shape, because it would have been too much work to clear them out entirely. If your kit has these braces made out of balsa, buy some 1/16 inch liteply, trace the shape, and cut them out of that instead.
  • The hatch also has some problems. The way it's done normally is it has a tongue on the forward edge which slides inside the fuselage and the rear is held down by the wing sitting on top of it. Well, twice now for me, during a launch with lots of pull to get the thing really up there, the wing has slid backwards far enough during the initial climb to eject the hatch. The first time I found the hatch but the second time I didn't and instead just built another one with magnets holding it in and the problem has never happened since.
  • The build manual says to hinge the control surfaces with the covering film. Don't do this. I don't get why anyone does this. It's just so incredibly lazy and stupid. Buy some CA hinges and use that instead. CA hinges catch a lot of flak from people that either don't know how to install them correctly or use them in inappropriate situations. Done right, there is no gap, and very little if any potential for lateral movement of a control surface. At the aero loads that a sailplane experiences, both of these things matter very little anyway.
  • Did you get the little bag of hardware including stuff like control horns and music wire? Mine didn't and I had to supply it myself but you have to be really careful with the control horn sizes. The way the elevator pushrod works is it gets routed through a little hole in the tail. It's actually really cool looking, and very clean aerodynamically BUT the hole in the control horn has to line up exactly with the hole there so the clevis will be able to meet up with it correctly without binding on the edges of the hole. You can move the hole up and down slightly but because of the rear doublers and the fuselage bottom there is not much wiggle room. The Goldberg 1/2A control horns were literally what this was designed in mind with to use and I was lucky to have a few lying around but otherwise Ebay is the answer since I don't think they're manufactured anymore. You also have to use the Goldberg mini clevises - I know the Dubro ones don't fit unless you drill the hole out really far into the fuselage. The Sullivan metal ones probably work, I just haven't tried it.
  • The wing covering is incredibly important to get right. Most RC sailplane wings get their stiffness more from the covering then the actual wing structure - so be careful mostly to shrink it all evenly and not cause warping and apply the edges nicely enough that they won't pull away when shrunk. Remember the dihedral braces I mentioned building out of liteply here? Well, they will also help save the covering a little. Before I added them, the added stress carried by the covering film meant it was constantly causing long thin breakages of the covering parallel to and directly next to the wing rib on top of the dihedral brace which I had to keep patching, and then patch the patches when they also got broken. I would suggest going over all the seams in the covering with an extra layer of clear covering, or if you're doing the wing all one color, just another layer of that color.
  • Speaking of covering. Use transparent stuff on at least the wing. Sailplanes, by nature, go very high. This is really fun, both to make the FAA angry and ride thermals all day :ROFLMAO: But - as you get higher, and farther away, eventually the human eye loses the ability to discern the color of an object that is not either translucent or actively eminating any light, something that solid color films obviously do not do. Arguably this is much more important on really fast planes and ones with roll control, but you should use transparent or translucent covering film. They remain very easy to see no matter how high up you go, plus they just look really cool.
It's 5:30 AM and I really should go to bed now. But I'll probably think of more later...
Wow, that was some great info - thanks so much! I’ll definitely note all of that and follow your advice. :)
 

The Hangar

Fly harder!
Mentor
#6
Go, Hangar, Go! Read what speedbirdted wrote and memorize it. This is exactly what a new builder needs to know! Every kit has its "Gotchas" and you will avoid them by following in the footsteps of an experienced builder. I listened to Joker's advice when I built the Sunbird glider, my first balsa build in 45 years. It came with horrible build instructions. It turned out lighter than most other Sunbird builds and is my favorite airplane for thermal hunting on warm summer days.
That’s awesome - I can’t wait to catch some thermals with mine!
 

The Hangar

Fly harder!
Mentor
#7
Oh dang, if only I had your advice a few years ago. I built my gentle lady all stock (except for adding spoilers, which is really easy, but optional). I too had to add some nose weight, even though I was using those big ol' futaba servos and a battery pack made from 4 AA's. I guess that's not too much weight in the nose. The hatch has fallen off during launch for me too. I had to make my own leading and trailing edges out of balsa since the kit only had enough for the inboard panels. The people at the field seemed impressed though. Maybe its because I'm the only young guy there with an interest in sailplanes.
I'm getting of track. Yeah, speedbirdted has good advice.


by the way, have you considered giving it an electric motor? Just putting it out there...
Actually yes - my plan is to add a motor. I don’t have any sloping sites and neither do I have a bungee launch, so I’m planning on putting probably a B pack on it .
 
Last edited:
#8
Actually yes -y plan is to add a motor. I don’t have any sloping sites and neither do I have a bungee launch, so I’m planning on putting probably a B pack on it .
Nice. Electric motors can get you out of trouble if you need to, and are more convenient to launch with. Although if you are going to put a prop on it, a folding one is best, and I don't know of any folding prop spinners that fit on a 6mm threaded shaft, if you have the radial motor or another motor with a similar shaft. The older EMAX motors from the power pack B will looks like they'll work fine. I dunno. there's probably something out there for threaded shafts if you are using the radial motor.
Or you could choose to go with the regular style prop. But those can break on landings and also produce more drag, and don't look as cool etc.
But you can cross that bridge when you come to it.
Anyways, have fun.
 

Yusernaym

Well-known member
#9
I have a Night Radian, which, being foam, is not exactly comparable to the Gentle Lady, but I've flown them back to back, and they're more similar than you might think. The Gentle Lady is, surprisingly, extremely responsive. It might just be the way my friend had theirs set up, but you have to be very careful with your inputs not to overdo it, especially with pitch. The motor is very nice if you're like me and not the best at planning your patterns. Getting a bungee launch is a lot of fun, and I highly recommend trying it at some point, but it's a lot easier to fly by yourself if you have a motor to launch with.
 

speedbirdted

Legendary member
#12
Bungee launches are actually cheaper. I use 60 feet of surgical tubing which costs about 30 bucks with 150 feet of 100 lb test line tied to it. However, electric power is certainly easier on your wings. Bungee launches are surprisingly violent :p

This is from the second time I tried bungee launching mine. We were using 30 feet of tubing. Later we used 90 feet of tubing which sent it twice as high but that resulted in audible cracking sounds coming from the wing during launches which I decided was probably bad, so we scaled it back and it's worked perfectly ever since.

 

speedbirdted

Legendary member
#13
Here's something I forgot to mention - I don't know if the manual says to do this or not, but glass over the seam in the center of the wing. I actually just got around to doing this recently, due to a weird incident where the glue joint ended up breaking and the rubber bands went through the leading edge of the wing. Glassing it both prevents this and will also make this joint much stronger. I used polyester resin and 1.5oz cloth but you could probably go still lighter and have it turn out just fine. The cloth is one continuous piece, going all the way around.

PXL_20201106_231410725.jpg
 
#15
Here's something I forgot to mention - I don't know if the manual says to do this or not, but glass over the seam in the center of the wing. I actually just got around to doing this recently, due to a weird incident where the glue joint ended up breaking and the rubber bands went through the leading edge of the wing. Glassing it both prevents this and will also make this joint much stronger. I used polyester resin and 1.5oz cloth but you could probably go still lighter and have it turn out just fine. The cloth is one continuous piece, going all the way around.

View attachment 182715
It does say on the wing plan to put a fiberglass strip on the joint. My kit supplied a piece, but I forgot about it too and still have most of it it lying around in the gentle lady box, which has become my scrap balsa bin. I did use some of it on my Willy nillies eaglet because I thought it needed it. But I’ve had no issues so far with the joint on my Gentle Lady (as far as I know).
 

The Hangar

Fly harder!
Mentor
#16
Here's something I forgot to mention - I don't know if the manual says to do this or not, but glass over the seam in the center of the wing. I actually just got around to doing this recently, due to a weird incident where the glue joint ended up breaking and the rubber bands went through the leading edge of the wing. Glassing it both prevents this and will also make this joint much stronger. I used polyester resin and 1.5oz cloth but you could probably go still lighter and have it turn out just fine. The cloth is one continuous piece, going all the way around.

View attachment 182715
It does say on the wing plan to put a fiberglass strip on the joint. My kit supplied a piece, but I forgot about it too and still have most of it it lying around in the gentle lady box, which has become my scrap balsa bin. I did use some of it on my Willy nillies eaglet because I thought it needed it. But I’ve had no issues so far with the joint on my Gentle Lady (as far as I know).
Oh, that's what that was for! I thought it might be fiberglass but I haven't worked with it so I wasn't sure. I'll make sure to get the wing halves all glassed up - thanks!
 

The Hangar

Fly harder!
Mentor
#17
Watching this.

The only foamie I still fly is your mini stick, @The Hangar. I've switched out my entire fleet to balsa over the summer. I like that little stick of yours so much I'm thinking of doing a version in balsa.
That means a lot to me! I really enjoy flying mine, and I'm always happy to hear from others enjoying theirs. :D
 

speedbirdted

Legendary member
#18
It does say on the wing plan to put a fiberglass strip on the joint. My kit supplied a piece, but I forgot about it too and still have most of it it lying around in the gentle lady box, which has become my scrap balsa bin. I did use some of it on my Willy nillies eaglet because I thought it needed it. But I’ve had no issues so far with the joint on my Gentle Lady (as far as I know).
Where did you use it on that? None of the WN airplanes need it anywhere. Just extra weight.
 

Piotrsko

Master member
#20
Trim it for a decent glide then muck about with the hook location from 1 1/2 -2 inch forward of the CG. Except for really high speed loops, you'll never break a wing if you dont pull up in launch. Downside is it wont get as high off tow. Hmmm low launch or broken wing nosedive.......

@Hai-Lee has a paragraph or two about launching somewhere here that's really good