The flying monkeys got me...

Helis, Fixed Wing, RC Sailing

AMA 957918

Pirate Kid Skeleton by RadDezigns.

Wednesday, November 25, 2015

Twinstar maiden goes perfectly!


The 4S, I learned, is a little tall for the hatch, so a piece of Velcro as tape holds it on. As an experienced builder ya think I would have test fit the battery before I left the shop...


Early afternoon, cold breeze from the south, sun
low on winter horizon standing unfetteringly bright just a few degrees above the southwest tree line.

The fall grass is thick and clumpy, but there are parts where its almost mud. I carry the Twinstar over to one of these barrens and face her south, down field. Check control surfaces, check flaps, check full power run up. Look, listen, feel. First flight. Be a good girl.

It's time. Full throttle, and she fights her way down the runway, such as it is, and as she clears the grasping grass and gains speed, the powerful torque of twin props rolls her to starboard. I easily correct and take her into a right climbing turn to clear the western tree line, avoiding the sun line. She gains altitude too easily. Nose down trim, a bit of left aileron trim, a tweak here and there, and in a few passes she is trimmed out despite a choppy wind aloft.

The power setup is spot on. The 4S nestled in nicely and she is balanced now. She won't go vertical, but she is aerobatic. In fact, my low aileron settings are too high for even high settings, and I had the low rate tuned to about 35%!

I try to slow her for a landing approach, a long one, but even with 50% flaps she is fast on the final. I need the higher aileron throws at approach speeds with the flaperons down. She descends nicely, predictably, but fast. Several landings and approaches, its just the way she is. And she puts her nose down when those back wheels touch the thick cabbage, and she buries her nose wheel and abruptly stops, stuck where she came to rest. It's a walk in taxi almost everytime.

A couple of times I manage to find a muddier less grassy spot and she rolls out. But her props are green with grass she had cut and thrown into her wings, and the green slaughter coats her props, belly and nacelles.

I fly two or three packs, at 10 min a piece I have already forgotten. She was quite an easy flier.

I had brought the 30cc gasser, but even after this fine flight set, I really am not in the mood, so we pack up and head home.

Flying is better with friends, but no one is home, so I fly alone, and thus my stay is brief.

It was a great maiden, good design, good build, good engineering.


Nose wheel is bent back by the grass.

Preflighting the Twinstar

Preflight testing of the Twinstar this morning, planning on a maiden today after some Honey-do's.
She has Sky Power 40A ESCs. The 480 Plus motors are rated for max 450 watts, but they caution running more than 400 watts sustained. I am running a switching voltage regulator instead of the BECs.

Ran the motors using the 3S 2200 mAh. I got about 7 min, 350 peak watts, around 35 peak amps. On the 4S 3300 mAh it peaks at over 700 watts, 37 amps! On time testing I got 15 min with some cells dipping to 3.4 V.

I need that flight time, so I set up a throttle curve and at a top curve endpoint of 50% produced around 430 watts, around 27 amps. At 50% of that throttle curve it produced around 230 watts and 12 amps, and gave me that 15 min runtime. The 3S 2650 mAh gave me about 10 solid min before.

So I plan to fly her 4S 3300 mAh set at 10 min with 5 min bingo, using a throttle curve to bring the power down so I don't blow the motors. I can fly the 3S 2650 mAh if necessary but would need to remember to remove the throttle curve. Not likely to do that.
More on the maiden later today!

Tuesday, November 24, 2015

Great Planes Twinstar EP Ready to Maiden!

Well, that's embarrassing... So I am watching the cat play with a white piece of plastic down in my shop... Wait a minute. Let me see that. Sonofabitch. It's the plastic Nose Gear bracket thingy. (Apologies to Great Planes...).

So I installed the nose gear and the nose cone, on the Twinstar EP, put a fresh 3S 2200 mAh battery in, checked CG (fine), and ran the motors at 50%.  Got almost 7 min, but it took them down to 3.5V. I need to see how it does with a 2650 mAh, or I will need to get the recommended 3800 mAh.



Trimmed that...



 






Bench test. Power to spare.  50% Throttle, 3S 2200 mAh, got close to 7 min but went down to 3.5V/cell.




I find their lack of faith... disturbing.





But for a nose block, the Twinstar is done.

The motor mount arrived from HeadsUpRC today, allowing me to complete the install of the port side motor and nacelle. All that is missing now, on The Plane of Missing Parts, is the nose wheel block, coming from Great Planes/Tower Hobbies. Once that is in, she will be complete within a few minutes, ready to CG and maiden.

After installing the port motor I ran them on a 3S briefly. Plenty of voltage/power. I wiIl need to see how much time I get on fresh 2200mAh. I am looking for 7-10 min of sport flying. I believe she is rated for a 5000 mAh or something ginormous. I already have a lot of connectors and adapters in there adding weight, but could easily change the EC3 one I have to EC5 and series in a pair of 2650 mAhs.



Saturday, November 21, 2015

Thursday, November 19, 2015

The Plane of Missing Parts

Does twice make a trend?

As my Great Planes Twinstar project has unwound I found I was missing a motor mount, now graciously on its way from HeadsUp RC, and today I found that the Nose Wheel Block, the white nylon part that secures the nose gear to the airframe, is also missing. I keep all the bags and boxes, checked, not there. I went through the trash, not there. I crawled around on my knees and belly looking on the floor and under the work benches, not there. I called Great Planes/Tower Hobbies and a replacement is on its way.

UPDATE:  They never sent me the part, which is okay because I found the missing one. Cat stole it. No, seriously.



Between these minor annoyances and the problems I had with the RCGF 10cc engine, I wonder if I need to tune my RC mojo.

I finished the wings, but for the left motor for want of the mount.





And installed the rudder/steering servo, and the elevator servo.



And finally the tail.




I am stopping here for today. Next time installing the control rods for the empennage and steering, the latter once the nose wheel block arrives. Looks like another week before she will be flight ready.

In the meantime I await the RCGF 10cc.

Tuesday, November 17, 2015

Eflite Stearman Maiden

Beautiful day, virtually windless. Perfect time to take the Eflite Stearman up for her maiden flight. The takeoff and first flight was hairy. Despite being on CG she flew a tad tail heavy, her DR and Expo were off (too low), and it took some sick skills to get her back down.

Over a couple of flights I found her happy place, she rolls like a pig, buy otherwise handles predictably. I enjoyed the flights and flew three long 3S 2650 mAh packs.