Christmas Curare EP

Yes.

PhilF51 wrote: Today, fitted the wing to get some idea of the CG balance point which is 95 - 110mm from LE. Thinking that I may have to extend the battery box with supplied bits, because remembering something about Mike's Angel's battery sitting quite a way back?

Phil, I measured my cg for someone else the other day, I am at 115mm from the LE at the root and I still want to get it a bit further back, so I think the designed cg is too far forward. I think my review said I was right at the rear measurement, but I have added lead in the tail since then.

Cheers Jon. Wings off the fuselage now but the figure you give looks more realistic. I'l try it again tomorrow with the 6 cell 4000 maH to see how that goes. Theoretically it should be somewhere slightly further back from where the tank would've been, allowing for the fact that the battery will be heavier than a tank full of fuel. It did in the qfimagazine review images.

Progress so far. C of G at 115 mm appears little more realistic Jon. Lipo sits up close to ESC as per the monochrome manual image. Photo 3

When the battery is inserted in position half of it is hanging out in fuselage with no support whatsoever and no back stop either! Photo 1 & 2. This will need to be corrected. Don't want 650 gms of weight floating around regardless. Made up a floor out of the spare bits of ply in the kit. See photos 4 & 5.

Power for the electronics is provided via a Turnigy UBEC 5A. Main power pack only has the motor to worry about. With everything ready to go I started moving surfaces as many as I could at the same time and watched the RX lamp. Still Red. good. Now sometime during these tests and powering the gear the lamp went orange. Drop out somewhere? A bit concerned here now.

Put an ammeter between the Lipo and UBEC. No wing attached but tested the current of the rudder, elevator and nose gear. Rudder and elevator servos peak at about 400 milliamps on first movement and then settle down to around 150 milliamps. However, the nose gear peaks at start at 800 milliamps. If you add in the the pair of mains, that 's another 1600 milliamps. Plus you have still got the aileron servos and possibly the flaps at some point in time. I appreciate they will not all be in use together, BUT.

Powering up the motor with the only 11 inch APC-e prop to hand which is 11 x 7, I got 1200 watts at 50 amps. (Which is a little less than the Wots Wot on the same motor on 5 cells swinging 13 x8 ) So, with a change of prop pitch..........

Weight wise I am still below the manuals 3.3kgs at 3.1kgs At the moment!

Whilst the Curare will fly well with a 11x7 prop, we have found whilst it sounds powerful, it actually just stirs the air and makes a lot of noise past about 3/4 throttle. Chris is running a 11x8 on his Wot4 and I'm using a 11x8.5 on the Blue Angel. These seem to load up the motor better and produce a much nicer result. You could also try a 12x6.5 or 12x8.

Regarding the UBEC figures...you said you put the ammeter between the LiPo and the UBEC? Surely this gives meaningless figures since it is the current delivered from the UBEC to the servos that is critical. You're running a 5A regulator and it is this OUTPUT that should not be exceeded. If you are exceeding 5A you might find that the voltage collapses, which is why you are getting a warning from your receiver LED.

If you are within 5A the voltage should remain virtually constant...that's the beauty of using a regulator instead of battery straight into receiver! In fact, a decent regulator should be able to maintain voltage even if the specification is exceeded for a short while, because it takes time for the temperature to rise to the point where the regulator reaches thermal cutoff.

Hi Phil

Just as an approximation, if you were running a 6s Lipo with the switch mode UBEC, the current drawn out of the UBEC at 5v will be between 2 - 4 times your measured input current. (Depends on the UBEC efficiency.)

You could reduce the peak current drawn by staggering the retracts, assuming they are on separate channels of course.

Mike, I had noticed that after about 3/4 throttle there did not seem to be much more thrust. I'll see if I have any 12 x ? APC props left and do a watt test tomorrow.

With regards to the amps drawn from the pack it was basically a quick check. Definitely need to verify current from the UBEC with my multimeter.

I had considered letting the ESC's BEC power the retracts but would probably make the wiring even more complicated and I might even forget how I did it in the future

I have ordered some decent 7.5amp SBECs (made by Hobbywing) so have a back up plan if the Turnigy's are over rated.

Jon - How are the flaps aligned. No hint in manual. Top surface level with the aileron and wing or laying central to aileron profile?

Other than the fact that the windy days are for us for days/weeks possibly till Christmas All's well.

Phil

Just look down from the trailing edge of the wing and centre the flaps and aileron by eye, you should be able to get it pretty accurate.

Cheers Jon. That's what I thought but wanted to verify. Flaps can be trimmed from the TX but need to set mechanically the two together first.