Discus CS 2.65m sailplane build
I've got a Flying Dream Discus CS 2.65m sailplane ARF from Nitroplanes and would like to turn it into a powered unit with foldable prop. I couldn't pass up the deal at $80. Originally set up for towing, this also has a retract, tow hook, and red plastic spoilers (so it is NOT like the photos in the link) but more like the Ventus 2HX shown below, just without the upswept poly in the wings tips.
No flaps on this bird though and I've read and seen the videos of the high wing loading and flimsy wings. This is the MkII version that has a steel wing joiner and plastic fuselage. It doesn't like to float (but certainly could with flaps right?), needs speed and just is sooo kewl looking and sounds awesome. I will need to sharpen my flying skills alot more to be able to earn the right to fly this unit. I just want to build it over the winter so not to lose interest.
Tony, (hopefully you're reading this) I know you said that you had built the CMPro Discus CS and converted to electric, would it be possible to borrow your built up Discus fuselage right next to mine while I tackle this project over the winter?
I'm sure that AUW will be as high as 1850 gm (65.5 oz) (4.07 lbs) when all is ready. I'd like enough power to climb at a good 80% angle, not concerned about vert. I could leave the retract gear in the down position to help save weight. I've read the spoilers don't really work as they are located in the wrong position on the wings and bind up. If possible, I like the idea of installing flaps onto the trailing edge of the wing to slow it down.
My Tx will be the Spektrum DX6i and I'll buy a AR6200.
Some build info I've collected.
- Prop: CAM 10 x 6 folding prop
- Battery: 2200 3s 30C Lipo
- AUWeight: 1500g
You may want to consider a geared drive as well. Bigger props have a better efficiency which usually makes up for the additional weight of the gear drive. I am using a Multiplex BL-480 system on my 3m Bird of Time (which is about the same weight, maybe even slightly heavier). This motor comes in different gear ratios to match the prop and speed of your glider. I'll post my exact setup when I'm home again.
Also, I found 3S enough for a good climbing rate. My Bird can do ~ 40...45 degrees with that setup which - I think - is plenty for a glider that size. 80 degrees would not look scale on yours anyways ... :-) The 3S/2200 is probably the most used battery size and can be used in many other planes as well. The size and weight should be perfect for your project!
Have fun building... Bernhard
Here's my exact setup for the 3M Bird of Time, ~70 oz AUW:
Multiplex BL-480 6G 3.3:1, 3SLipo/2200, Castle T-Bird 36A ESC, 14x8 folding prop.
If you don't want to spend the money for a geared motor, pick a setup around 300W with low kv rating to get the largest possible prop. Webpages like hobbycity usually do have lots of prop size suggestions.
Thank you for the suggestions, very helpful. Looking at the other setups everyone did not choose a geared motor solution, very clever of you!
How do you mount the geared unit and motor - similar as an outdrive, to a firewall? The small space would work well for an indrive unit as the motor casing wouldn't be turning.
I didn't find the Multiplex BL-480 geared box on the Multiplex US website, where is the best source for this? Of course a Graupner unit woul be fine too. Thank you again Bernhard.
Cheers, Thompson
Those motors behave like inrunners... mounted to the firewall and no moving parts in the cockpit. The small diameter of the gear is perfect for those narrow glider fuselages.
I got mine from Sal (nesail.com) back when Nick was still there. Here's the link:
http://nesail.com/detail.php?productID=3212
Here's a more affordable inrunner solution (no gear, but low kV):
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9449
Looks like you can configure this motor anywhere from 200...450 Watts, depending on battery (3S, 4S) and prop size. That should be plenty for your plane.
I'm curious about the kit quality of those Nitroplanes gliders. The price looks amazing, but the reviews are mixed. It seems to be difficult to find a larger glider for a decent price. And they also offer a 4m Ventus... very tempting.
Keep us posted!
I will bring my setup for you to view on Wednesday.
Tony
Glide test without flaps and flaps installed. http://www.youtube.com/watch?v=EAeR0Zt080g "RodrigoV" (see setup above) http://www.youtube.com/watch?v=xiW3npmje1c http://www.youtube.com/watch?v=vyKNk54Ujj0