At long last, after so many kits, ARF/RTF bashing, and scratchbuilt foamies designed by others, I finally decided to have a go at my first ground up design/build/fly project. The concept follows up on the sort of fun I've been having with my SA Adrenaline Rush & Avionik D99. I'm shooting for 100mph to begin with, and plan to go up from there. Here's the basics:
Span - 27"
Chord - 4"
Wing Area - 85 sq. in.
CG - 34mm aft of root LE
Length - 24"
Dry Weight - 3.5oz
Motor - Turnigy 2730-3000 (rewound 6x2T-24awg-Y)
ESC - Phoenix 25 (outrunner mode, insensitive current limiter)
Prop - APC 4.75x4.75e
Lipo - TP 3s850 30C (a Rhino 3s1250 30C fits in the fuse, bigger hatch required)
Servos - 2@ D-47's
Rx - AR6110e
AUW - 8.7oz (w/ the TP 3s850)
A few more gory details...
The wing has a true elliptical planform with a parabolic sweep toward the TE. It is cut and sanded from 3/16" balsa, and reinforced with 18" long 4mm carbon strips sunk flush on top and bottom. I glassed the wing with one layer of 0.5oz running tip to tip on bottom, and 2@ 45deg biased layers of 0.5oz on top. Ailerons are skin hinged. The ailerons run inside the fuse and terminate with phenolic horns. The tail section is sanded from 1/8" c-grain balsa, and the elevator is hinged with Welder glue. The fuse has a 5/4mm carbon tube running from the firewall to the tail (inspired by Steve's AR). A curvy 1.5x1.5x1/16" balsa box streamlines the electronics (top and bottom nose sections are actually 2 plies of 1/32" balsa). I fly in rough areas, so the fuse bottom is reinforced with 1 layer of 0.5oz glass. The hatch is pressed with 2 biased layers of 2oz glass; I glued balsa bits inside to keep it from sliding around, and use clear 'Plastic' tape to hold it on. The paint is acrylic lacquer with shellac primer and a stiff microballoons mix for filler.
Overall it looks and feels the part... hope so 'cause maiden is tomorrow!
[edit: MAIDEN WENT GREAT!!! - Dopplered 112mph upwind on a 10mph day, in the middle of a turn. Not bad for a $10 motor!!!
'Un-Named' Pylon 300 Scratchbuild - Brian's Perspective
(6 min 47 sec)
Here is a more recent video I shot with a rewound Microdan MD2505, running about 25A with the same lipo/esc. This video does a better job of showing how the plane turns and handles at various speeds.
Elliptical w/ Microdan custom wind
(4 min 17 sec)
After I shot this video and was packing up to leave the field, I accidentally slammed my left wingtip in the door of my truck. It catapulted across the cab and bounced back and forth a few times. Only damage was a slightly dimpled left wintip, and a split hinge near the left wingtip. I used 'plastic' tape to repair the hinge and it has been working fine for several flights. The plane has also suffered a pretty bad cartwheel with zero damage. Tough as nails...
I recently widened the hatch opening 1/8", made a new hatch, and stuffed a Rhino 3s1250 30C in there. To take the extra amps, I had to upgrade to a Phx35 esc (same settings). Flight times as a result of over-current cutoffs are around 1.5min, which I guess is what I should expect with 32A static even without the current protection acting up. I also recently balanced the motor rotor/prop together. It's a lot better now, but the motor is in need of new bearings. I'll post more video after I get new bearings and everything is running well, but it already feels faster with the sloppy bearings... very easy to doppler too, LOL!
Sept 20, 2011: It flew OK with the Microdan, but the loud bearings got old. So I swapped in the original rewound Turnigy motor and got her ready for a batch of experimental flights with various custom props; the MD2505 awaits new bearings and further testing before it gets reconsideration for duties on board the Eclipse. When that Turnigy is driven >30A with the bigger Rhino, I got a feeling efficiency is going to hang on longer than the MD2505. Even if I get the same RPM, shaving 11gm and having 34% less "drag area" hanging out front (due to the smaller diameter rotor) should add up to a decent increase in speed. Exciting stuff... wish me luck...
Oct 3, 2011: Test flight with the Turnigy motor and larger Rhino pack went good and bad. It was waaaaaay faster than before... while the motor was running. The esc kept going in to LVC after a half lap around the course. I tried resetting throttle 3 times during the flight, but it didn't stabilize so I landed early. This is better than having overcurrent shutdown at 3A less than the esc rating. More than likely a better pack will get it going strong. I plan on getting some Hyperion EX packs (3s1100 45C) and swapping out the chinese 3.5mm bullet plugs with Hyperion 2.5mm bullets. I think that should cure my problems with voltage sag, but I hope it doesn't push me out of Phx35 territory. We shall soon see...
BTW, if you've been lurking through this thread and are interested in making one for yourself... I'm still working on (free) plans. I took lots of photos during the build, but the plans were sketched with paper and pencil. I've got a bit of work to do before I can effectively communicate the details of this design; although more experienced builders should be able to hack it through with just the specs I provided.
Oct 9, 2011:
Wing plans added.
The dotted line is the max thickness line; some taper is added near the tips.
I am putting the finishing touches on a new custom 2730 motor that looks to be a tad faster than anything I've tried so far.
Oct 16, 2011:
I met up with the guys at Elk Grove today and tried out that new 270W 10 pole 2730 motor. It did add a little boost in speed. Doppler of the video below shows consistent 125mph passes... no F3S style dive in, mostly level flight with hard turns. The 10p motor seemed to make a big difference in reliability. Although LVC was kicking in early (weak old Rhino pack), the motor still pulled 125mph passes near the end of the flight. This new motor really likes to unload. So my next experiment will be with a higher Kv wind... we keep going until there's either no more room for battery, or the motor can't hold in the magic smoke. This plane is just as fun as my Sokol and D99!
Eclipse Pylon Racer - 3350Kv 24gm motor
(2 min 11 sec)
Oct 23, 2011:
Here we go again... this time with an APC 4.0x4.75e cut from a 4.75x4.75. Doppler averaged 115mph. The pack hung in there and LVC didn't kick in for about 2min of WOT flying. This is good, and what I was looking for with 10p... but where I'm headed I will need a lot more power. Hyperion EX packs are on order. After I get a baseline with those packs I plan on pouring on the Kv! What's a good next step... 4000Kv?
(3 min 1 sec
Dec 4, 2011: EX pack arrives!!!
There's been many changes to the power system... time to review my current best setup and weight:
Motor - Turnigy 2730-Custom (10p flat silver magnet rotor, 6x2T-24awg-Y stator)
ESC - Phoenix 35 (insensitive current limiter, fast throttle response)
Prop - APC 4.1x4.1e (w/ heavy HK prop adapter for ballast with EX pack experiments)
Lipo - Rhino 3s1250 30C
AUW - 10.2oz
I just received a Hyperion EX 3s1100 45C lipo a few days ago, but I included the Rhino in the above specs since my preliminary tests have shown it to be better than the EX pack. Let me explain... I redid all my connectors with high end Hyperion 2.5mm bullets, charged up the new EX pack at 1C (as I do with all my lipos), and ran a test. To my surprise the EX pack flopped, providing just 11.1V/27A. Even my beat up old Rhino pack did better at 11.3V/29A. After that 10sec bench test at 27A, I completed a 5A continuous discharge on the EX pack using my iCharger (to 3.2V/cell). It did put out 1050mAh, but cell #3 ended up 0.2V lower than the other 2. Did I get a dud, or am I expecting too much out of the pack? For the price I paid, I sure hope it's the former!
Unfortunately I think it's the latter case, but I'm not giving up on hope on more speed for this coming weekend. I will try a few 3.3A 'break in cycles' to see if it helps. If not I will contact the vendor where I bought it; they're known for excellent service, so I may get a replacement before the weekend if I can finish my testing tonight. So far on the second break in cycle it did 1040mAh and with slightly improved balance (discharge ended fine, but the 3rd cell still stabilized 0.13V low after cooling off). Not a good sign, but I'll give it another cycle before I fire off that e-mail.
Feb 3, 2012: Turnigy Nanotech 3s1000 45C
The past several weeks I've been flying the Eclipse with a new pair of Nanotech packs (the ones named in today's title). The setup is otherwise identical to what I've used the past 2 months; but lighter and perhaps even more voltage than with the Rhino packs. So far those nano's are really putting out the stuff. In the first minute and a half of a flight I can't do anything to get the LV cutoff to trigger. The Eclipse feels faster to me than the Rhino's, but I can't say for sure without evidence. Life has kept me too busy to bench test with the nanos, but the weather has been great lately; doppler coming soon...
Feb 5, 2012: Superbowl Fix
Made it out to the field on the way back from running errands. I got a quick flight in... 130-135mph now, and loads of fun too!
Eclipse 300 - Micro Pylon Racer Prototype
(2 min 46 sec)