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Mar 12, 2017, 05:36 PM
ama 1390
pval3's Avatar
Thread OP
Help!

What do I have and what do I need to get these two 2m sailplanes in th air


Hello all
Got a little carried away at the BARKS swap meet and walked away with more than I sold... it's not an addiction.. it's a hobby
I picked up two V tailed 2meter sailplanes that are very similar for the kids to fly... but they are not the same..
the yellow and red one is very solid..thin clean airfoil . think there is a good bit of carbon in the wing and very very solid.
Green and red fuse has no markings but is about 25% lighter but more rigid than the red tail. It has an Astro sticker on the nose and that is about it. The mounting holes line up with a speed 400 mount.
Other is a little beefier but still super light.. it has an outrunner from hobby lobby buried in the nose. looks like model number sk40_xt in the front that is fried. Thought it was going to be easy but no good deal goes unpunished
I've checked the incidences and the things are straight and true..The builds were done right so I think I got a pretty sweet deal but need to set them up.
Can y'all check the pics and offer any input for motor, prop and battery set ups
Need to get that old motor out.. any suggestion on threads with how to undo the firewall.
Thanks
Phil.
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Mar 12, 2017, 06:43 PM
Sailplane Mafia
gquiring's Avatar
Go with GliderDrives from Hobby King. They are designed for sailplanes. They are an outrunner but the outer can does not spin. So they can touch the fuse. The wires come out the back. I would use a Yep 60 ESC on them. 12x6 Graupner folding props. I have Gliderdrives in almost all my sailplanes, they are great motors.

GliderDrive SK3 3850 960kv
https://hobbyking.com/en_us/turnigy-...3-5-960kv.html
Mar 12, 2017, 07:23 PM
ama 1390
pval3's Avatar
Thread OP
Gquiring.. thanks for the reply. Never sw those motors before.. perfect for a larger project I was working on but way too wide for this app. I think the motor in the one is somewhere in the 24 to 28mm range... an old speed 400 drops right in the one.. the other has that drop back motor mount with the prop shaft poking through the original mounting plate.
Mar 12, 2017, 07:25 PM
ama 1390
pval3's Avatar
Thread OP
The green and red one has an edf motor in it for sizing and spacing grins and giggles but far too high a kv to work a sailplane.
End bell in 28mm for ref.
Mar 12, 2017, 08:40 PM
B for Bruce
BMatthews's Avatar
I'm sort of thinking that 500W motors are also a bit much for a 2 meter model. But that may just be me and my more sport flying approach to things.

100 watts per lb of total flying weight will give you a nearly vertical climb. After that it's how fast you wish to go in a vertical direction. A good flying weight for a 2 meter model is typically down around 30 to 40 oz or so depending on the model. So if we use, let's say 120 watts per lb for a solid vertical climb ability then we only need a motor of around 200 to 300 watts.

If you'll be sport flying these models and can live with more like a 60 climb and a time to around 400 feet of about 20 to 25 seconds you could reduce the motor power to more like 80 to 90 watts per lb. That would put a little more focus on the gliding by reducing the weight with a smaller motor and pack.

You're on the right track with first finding a motor that will fit the nose of the models. Then it's just a question of which one will provide the power you want and a Kv value that will work with a reasonable size prop. From what I've seen a 12 inch prop is overkill and will require an excessively low Kv value. Also even when folded the larger size of the blades will be a touch more draggy. I feel that a good compromise between being larger and slower turning to aid the climb and small enough on the blades and hub to lower the folded drag is likely around the 10" size. This wouldn't be a competition approach but more a sport flying approach.
Mar 12, 2017, 09:50 PM
Sailplane Mafia
gquiring's Avatar
The way I have them configured with a 3s setup they do around 350 watts which is about what you want for a 2 meter sailplane. But if the motor won't fit then not much you can do but go smaller.
Mar 12, 2017, 10:43 PM
B for Bruce
BMatthews's Avatar
Quote:
Originally Posted by gquiring
The way I have them configured with a 3s setup they do around 350 watts which is about what you want for a 2 meter sailplane. But if the motor won't fit then not much you can do but go smaller.
I'm always looking for performance data points and this sounds like a good one. How heavy is the model and what is the climb angle and speed with it running at that power level please?
Mar 13, 2017, 08:41 AM
Sagitta Fanboy
YEP 60's are way overkill with a Gliderdrive 3850, most applications shouldn't need more than a 30A ESC, and even if you load it all the way up it only needs a 40A ESC. A 3850 with a 12x6 is going to be a rocketship on most 2m's.

The Gliderdrives are a little porky for their power output, so they're best used in applications intended for somewhat heavy but underpowered motors (they're great for conversions from brushed motors)

350W is overkill for most 2m ships. 150-250W is typically what's needed, depending on weight. You could run as little as 125W for one of the new ultralight 2m's, while a heavy 2m like a Spirit in the low 30oz range probably needs 225-250W.
Mar 13, 2017, 11:10 AM
Sailplane Mafia
gquiring's Avatar
Quote:
Originally Posted by mawz
YEP 60's are way overkill with a Gliderdrive 3850, most applications shouldn't need more than a 30A ESC, and even if you load it all the way up it only needs a 40A ESC. A 3850 with a 12x6 is going to be a rocketship on most 2m's.

The Gliderdrives are a little porky for their power output, so they're best used in applications intended for somewhat heavy but underpowered motors (they're great for conversions from brushed motors)

350W is overkill for most 2m ships. 150-250W is typically what's needed, depending on weight. You could run as little as 125W for one of the new ultralight 2m's, while a heavy 2m like a Spirit in the low 30oz range probably needs 225-250W.
I prefer larger ESC's so I can move them around without having to repurchase ESC's all the time. Every glider I own is tail heavy so extra weight is needed anyways in the nose. That glider drive will easily pull over 30 amps so a 30 amp ESC would not be a good idea. I would never fly a 2m glider with a 150w setup, it would be underpowered. Many have to share a field with powered planes and will want to get upstairs fairly quickly to avoid any issues. I prefer 20-30 seconds launches you get up quick and clear the area of other powered planes.
Mar 13, 2017, 12:22 PM
Registered User
craigrrr's Avatar
I am a cheapskate, so I like high quality, but cheap stuff.

On several of my planes including my 1000 gram Introduction I use a KEDA28-39 (used to be called a KDA20-22L) outrunner.
On the Introduction I have a good 1300 3s LiPo, CAM 10-6 prop. This yields 24.9 amps, 296 watts. This results in a nice steep nearly vertical climb.
I also used this motor on a Phoenix 2000 and a Vista.

The motor is a little bit heavy: 87 grams, Kv=1000, 28mm dia x 39mm long, 3mm shaft. It says it is rated at 200 peak watts, 10 peak amps; but this is a mistake. Peak amps used to be listed as and should be 25. This is a rock solid motor; I have had zero failures and have owned lots of them. I have also reversed the shaft for in front of firewall mounting when appropriate; they come with an extra shaft.
It costs $10.
Mar 13, 2017, 12:30 PM
Sagitta Fanboy
Quote:
Originally Posted by gquiring
I prefer larger ESC's so I can move them around without having to repurchase ESC's all the time. Every glider I own is tail heavy so extra weight is needed anyways in the nose. That glider drive will easily pull over 30 amps so a 30 amp ESC would not be a good idea. I would never fly a 2m glider with a 150w setup, it would be underpowered. Many have to share a field with powered planes and will want to get upstairs fairly quickly to avoid any issues. I prefer 20-30 seconds launches you get up quick and clear the area of other powered planes.
150W on a 500g bird is certainly not underpowered, and yes, 500g is a realistic weight for a modern wood e-launch 2m (there are several sub-400g line-launch 2m's these days, stick a motor in an X-RES and you might come in at 450g with careful component choices). Even on a 600g ship 150W should get you to 200m in 30s (I was getting 200m in 30s on my 650g Conscendo S pulling 14A on 2S for about 110W)

The 960Kv Glider drive maxes out at 35A, on a setup that isn't overpropped you can readily keep things under 30A. Propped for a typical 250W setup suitable for a 32oz ship you should be drawing no more than 25A on 3S.

I spec out my power systems at 100-125W/lb, for a 20-25s climb to 200m.

Unless you're motorizing an early 80's lead sled in the 35-40oz range, you don't need 300W to get a decent climb for a 2m.
Last edited by mawz; Mar 13, 2017 at 12:38 PM.
Mar 13, 2017, 12:37 PM
Sailplane Mafia
gquiring's Avatar
Quote:
Originally Posted by mawz
150W on a 500g bird is certainly not underpowered, and yes, 500g is a realistic weight for a modern wood e-launch 2m (there are several sub-400g line-launch 2m's these days, stick a motor in an X-RES and you might come in at 450g with careful component choices). Even on a 600g ship 150W should get you to 200m in 30s.

The 960Kv Glider drive maxes out at 35A, on a setup that isn't overpropped you can readily keep things under 30A.

I spec out my power systems at 100-125W/lb, for a 20-25s climb to 200m.

Unless you're motorizing an early 80's lead sled in the 35-40oz range, you don't need 300W to get a decent climb for a 2m.
I don't have a single 2m plane that weighs 500grams!! Are you talking Pulsar's here? Come on look at his photos, those planes are going to weigh in around 2 pounds with the goods in them.
Mar 13, 2017, 12:43 PM
Sagitta Fanboy
Quote:
Originally Posted by gquiring
I don't have a single 2m plane that weighs 500grams!! Are you talking Pulsar's here? Come on look at his photos, those planes are going to weigh in around 2 pounds with the goods in them.
No, recent F3-RES designs are pretty much all 450g or less, with the low end in the mid/high 300's. All wood or wood with carbon spar/boom. E-launch versions are typically 450-550g. 150w is the low-end of the range I suggest for 2m ships, he probably needs more, but he should be fine in the low/mid 200's for wattage with those ships. These F3-RES designs are rapidly gaining popularity.

The Radian is 2lbs with a BL480 pulling 22-23A on 3s. Climbs like a rocket. My Radian Pro pulls 235W on 3S at 31oz. No way those birds need more power than that.
Last edited by mawz; Mar 13, 2017 at 12:48 PM.
Mar 13, 2017, 12:52 PM
Sailplane Mafia
gquiring's Avatar
Quote:
Originally Posted by mawz
No, recent F3-RES designs are pretty much all 450g or less, with the low end in the mid/high 300's. All wood or wood with carbon spar/boom. E-launch versions are typically 450-550g. 150w is the low-end of the range I suggest for 2m ships, he probably needs more, but he should be fine in the low/mid 200's for wattage with those ships.

The Radian is 2lbs with a BL480 pulling 22-23A on 3s. Climbs like a rocket. My Radian Pro pulls 235W on 3S at 31oz. No way those birds need more power than that.
What you are talking about with the F3-RES and what this guy bought are not the same class. I looked up my notes on my 2m ship and it weighs 2.8 pounds with a 325 watt motor and 2200 3s lipo. No run of the mill 2m glider is going to weigh 500grams unless you buying some high end competition ship.

Go look at the new Radian XL, 2.5m. It weighs a whopping 5 pounds. Using 500g as a reference for a 2m glider is not realistic for the average sailplane out there.


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