10cc Sukhoi Cowl On!

It took an absurd amount of work to get the cowl on. I had fitted it to get the length for the engine weeks ago, but once I had everything under the cowl the fitting work began. I had to flip the ignition upside down so it hangs partly down into the fuse, then I had to Dremel down openings to get the spark plug and muffler to clear. In the end the holes are a little bigger than planned. But judge for yourself, she looks sweet!  I think she needs a black prop though!

RCGF 10cc Happy Happy Joy Joy!!

I have been sharing the troubles I have had getting this simple RCGF 10cc engine to work. It got to a point that everything had been checked, checked three more times, rebuilt, and yet no one could figure this out. My latest failure was a downer, as there was nothing left to do.

I never lost hope because of the personal attention and guidance I got from Joe Nelson of RCGF-USA by phone and email. This not starting made no sense. He reviewed the Electric and Fuel video and he could find nothing wrong. He responded to my last email never giving up, and we went back to what we knew: too much or no fuel?  I knew it wasn't flooding. This was an obvious question given starting the engine with an electric starter, and several times I had checked the spark plug and it was dry. This left not getting fuel.

Again, no sense. I could see fuel getting to the carb. Joe wondered if it wasn't actually getting in, and suggested I try choking the engine. This one doesn't come with a choke, generally is small enough it doesn't need one. So he suggested putting my finger over the air inlet and choke starting it. As soon as I read the email I was out in the garage, my finger over the inlet, and putting the starter to the spinner...

Now that its running, I ran it, stopped it, started it, over and over and she just get working like there had never been anything wrong! I think its time to put the cowl on!

I have two of these engines. As you may recall, Joe sent me a brand new engine and told me to keep the first one as he had discharged it as non-functional. I plan on putting that engine in the Spitfire I will be building this winter. If she runs, I will pay him for this one too, discharged or not!

If things continue to go this well, and I can get my engines from Joe, RCGF is now my engine maker.

RCGF 10cc Electrical and Fuel Setup

As I work on trying to get the newer RCGF 10cc engine running, I am sharing my setup for comments and ideas on what might be going wrong with it, why I can't get either engine to run.

UPDATE: She runs! Turns out it was something simple.

Please watch it, and comment! The first half is electrical, middle shows proof of spark, then fuel system, and the last part is all the stills you need to see the engine and setup.

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!

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.