Hi Will,

Your Bomber looks awesome! I have heard that it flys like it is on rails, and weighs 75 oz. With your higher Reynold's #s that makes for a good wing loading. And with the modern airfoil it looks like you have another winner in your stable of ECL contest planes. :-)

Your imagination is an inspiration to all of us who would like to have a unique, good looking competitive ECL plane. Please keep us posted with more details. Like: How much do the smaller Hackers weigh? How do these small motors turn those large 12 x 6 props? What RPM? Are you around 5 sec lap times? E to E line length? How did you like using the CF veil covering method? Are you using the new Jeti "Spin" ESCs, if so how do you like them? ..... TIA for your info. :-)

Congratulations on finishing such a great ECL plane. With your busy work schedule, I don't know where you find the time. I'm retired and it takes me months to finish an ARC? ;-)

Regards, 

Thanks Rudy, thanks Mike;

It took me a year to design this machine.  I originally fitted AXI 2826's but found them more power
than necessary.  they also whined in manuevers when I used Castle Creation controllers.  I shifted to
Jeti Spin ESC's which allow brake in helicopter mode, and they do not send a screech signal to the
windings of the outrunners in heavy loading.  The hacker A 30's weigh 5.1 oz, can withstand about 33 amps
constant and up to 18 volts.  I have not put eagle tree measurements on it yet, but I think they are
drawing about 25-28 amps each, but maybe less.  They swing the 12/6 with ease, and produce this cool
beat frequency in flight, due to the not quite sync'ed rpms.  I'm using a JMP gradual 3rd speed ramped timer,
using the first speed to zero for 30 sec. to get to my handle, the 2nd flight speed is a gradual ramp up to full
power( program adjustable in the ESP) in 15 seconds, for realistic take off - which allows me to keep the bird on the ground for a quarter lap per takeoff req. in the book - and then a gradual additional ramp up 3rd speed for voltage drop compensation.  I am not using heli mode.

I fly on .018, 66 feet eye to eye, and fly between 5.1 and 5.4 sec lap speeds.
the bird turns on a dime, and can do square eights all day long -  the power is crazy.  when I first flew
this airplane in test flights, it actually scared me - I've never flown and built or owned such a big bird.
but then I started feeling the "groove" and it is quite remarkable.  It does not like wind above 10 mph,
as it gets pushed down on 45 degree maneuvers like the outside squares- probably because of it's weight..  It likes 5mph .  Of course most airplanes probably do. 

Airfoil is based loosely on a Dave Cook Lightning design, with additional 1/8 inch thickness.  I used Tom Morris tech. in wing construction. There are no open bays - everything is planked. Aspect ratio was increased slightly, Fancher wingtips added for lift and efficiency.  Tail moments are longer than normal.
thrust lines are centered across the wing.  the Nacells are out further on the wing than you would expect.

I'm making modifications to the stab - it's not big enough, as the airplane sometimes rocks in the last corner of inside squares.  And I'm still trimming out some issues with line tension..I am also changing the tri gear to conventional two wheel to lessen drag.

the counter rotation props seeem to cancell out some vectors.  And the wing has more lift than you would expect
probably because I have 24 inches of 100 mph air blowing over it.

Do you think the paint scheme is too radical for contest work ?  Is the design too radical ?

I'd appreciate some constructive feedback...

thanks again,

Will Moore

Something went wrong with the last post

No.2  Why not kit this, make a superb ARF


Vincent

So an ARF then, motors installed , bolt on wing , tail , fin
with only then to plug in the components and , having
charged the battery,        go fly

that would be heaven !!

Vincent

Hi Mike;

thank you very much for the suggestions

I do not have trouble with line tension - it pulls like a horse - so I'm actually looking at adjusting
motor thrust and eyelit position to balance that out.

It has been observed that that I've trimmed the model slightly tail heavy already.  I've sinced
moved the battery forward and it has smoothed things out.

This airplane turned out heavier than I wanted I think because I planked it instead of using
open bay w/silkspan and dope.  What's happening is that the wind tends to push it down when it's at the 45degree
position before the first corner of the outside square loop.  All other manuevers are fine.  It does not wind up
during consecutive loops, either.  I also think the wing airfoil is not quite up to "modern" standards - it
may be considered too thin by some.  I'm still trimming though, so some traits might be trimmed out.

what do you think of the nose ? I struggled with the canopy position.  I think now it should be moved back
to maybe the center of the wing, and the nose re-shaped to a more graceful point. Some have commented that
that may be better. 

I might end up trashing the camo altogether and paint it with more "classic" colors and lines. You know, like white with blue and maroon striping, or whatever.  I've changed the tri gear to two wheel and flew it.
From inside the circle, with two wheels raked forward under the wing, it looked better and more "normal"

Please continue your imput - I will not  be offended no matter what you say - I promise!!!

and Mike , I'm flying with 12/6 APC electrics , counter rotating, tractor and pusher. They bite into the air with authority and just eat op the sky with any speed between 5.1 and 5.5 sec. laps.  I'm using about
two thirds of the power available - the Hackers together can produce about 800 watts - much more than what
I need.

His Steve;

Thanks for the kind remarks...although I did not place very well this year at the contests.

But you are ! - you and Rick are neck and neck at the top of the heap in NE

by the way, great pictures - keep doing it


Will Moore

Hi Dennis,

Will does not get a chance to come on this forum very often so I will try to ans. some of your questions. Will asked for my help during his design phase so I can take about .0001% credit for the results. ....... Will may say it is even less?   

1. No. ...... Our model "brushless" motors require their own ESCs.

2. No issues with sync. ...... They run very close to the same as they came out of the box. Someone could develop a "sync system" if they want a perfect hummm, but it is not needed.

3. Yes, the CR props are worth it. Even more so for CL planes.
      The 12x6 APC props are perfect for this set up. There are more pusher props available than there used to be. APC and many of the European brands make them in most sizes. .... The 2S IC CL engines have very unique prop needs (very low pitch vs dia), this really limits our prop availability in the 2S IC CL world. ......  ECL uses the more normal props used by many tens of thousands of E flyers ( and 4S flyers) world wide. Our ECL prop selections are much more available.

4. From the pilots view in the cockpit: Counter-rotating propellers generally spin clockwise on the left engine (like our IC and E power normally does), and counter-clockwise on the right. The advantage of counter-rotating propellers is to balance out the effects of torque and p-factor, eliminating the problem of the critical engine.
      In CL this is a big help when we pull hard corners which changes the direction of the gyro (prop) and the airspeed at the same time. The "P" factor (gyroscopic precession) combined with the torque of two 12" props can cause problems with a large twin CL in turbulence and in the corners. The CR props helps with this. The engine out problem (critical engine issue) is not so important with the fantastic reliability of ECL, but would be important if one wanted to make an IC CL twin.

There are many advantages to having a twin in CL. The E power solves all the down sides and leaves just the advantages. Having two 12" fans accelerating air over the lifting surface and pulling like a freight train through turbulence makes twin ECL flying even better than our single ECL systems. Will is already working on some improvements for "Bomber #2. Hopefully we will have one on each coast next year, so more people can see ECL at it's best!

Thanks for the tip RE: the 45 degree in the wind problem. That is a good tip for all of us. :-)

I'm going to be talking with Will today, I'll make sure he reads your post. I'm sure he will appreciate your kind words.

Regards, 
Rudy

Will:
Congrads on an ambitious project.   

I have had a couple twins - CL & RC and as much as I like them I swore "never again" - unless e-powered!  I like the round cowls - seems a natural with the round (albeit SMALL) motors!  I like that you can then style the fuselage to you wish. 

Couple questions on your set-up: 
1.  As I understand you have one battery, two ESC's & 1 timer.   Is it possible with brushless to wire them to a single high capacity ESC?  (the prize being simplified programming) I seem to recall that RC guys wiring BRUSHED motors that way...

2.  Did you have any particular issues getting the dual ESC's & motors running the same?  THis is more of a production variation thing - I'd like to think that electronic componenets would be MORE repeatable than IC engines - but...?

3.  Do you think the counter-rotating props are worth it?  The biggest downside I can think of is it might limit your prop selection to just what you can find in opposites.

4.  Really dumb question: which side gets the "normal" rotation and which the LH rotation?  I understand that even in full size there was some diference of opinion over which chould go where!

* It sounds like your problem climbing/holding 45 deg in wind might be something that you can overcome with technique:  in high wind I always make sure that I am at or above 45 at least 1/4 lap before going down wind.  Use the upwind side to pick-up the airplane, then aggressively hold it there.  If you are a little high the wind might blow you down some but still be at 45 when you start the maneuver...

AGAIN CONGRADS ON THE GREAT PROJECT!

Steve Y:
Kudoes for another GREAT set of pixs!

Hi ECL Gang!

Great News. I have it on good authority that Will Moore is working on "ECL TWIN II". It looks like it will be an article/plan in a major model Magazine.

His new twin will incorporate many of the good qualities of Twin #1. The same excellent E-power system: Hacker motors, Jeti ESCs, JMP Controller, 14.8V 5,300 mAh battery, Eagle Tree data system. Very similar wing, and moments (If it ain't broke, don't fix it! ;-). Most likely it will have a sleeker fuselage to appeal to the CL judges and be more like what they are used to seeing in the normal sleek CL planes.

To my knowledge Will's twin is only the second ECL twin ever flown in compition. Mr. Burnell (Sp?) was the 1st. Will is to be commended for his work in this area. His twin is a great flyer, and paves the way for others in the future. I hope we can all encourage Will in his magazine article project. This should be a great promotion for ECL and increase interest in this excellent power system for CL. :-)

Maybe this post will also encourage Will to post some photos of his #1 Twin ECL plane that now has the LG in the correct place, where mother nature intended LG to be! I told him I would put a hole in his Sailboat if he did not get rid of the "training wheel up front" LG arrangement! He really likes his Sailboat, so he lamented. Now it looks MUCH better! 

Regards, 

Hi Clancy,

Thanks for the cool photos. The P-38 is a fantastic plane. Kelly Johnson was a true genius, not only because of his great designs but because he brought them to production in a very short time period. As everyone knows, he liked SPEED and EFFECIENCY above all. From the P-38 to the SR-71 these two priorities were paramount.

The laws of physics do not change (even for Kelly ;-). BUT, as we all know, aircraft design is made up of a constant selection of compromises. Designers are always faced with trading off one benefit for another. It just depends on the planes mission. A fighter planes mission is different from flying passengers, or one doing tricks tied to a string, and the compromises will reflect these different missions.

On the P-38 Kelly found a gain in efficiency and SPEED by having the props rotate contrary to standard principles (on that specific twin boom design) and he was willing to trade these gains for a small loss in single engine performance and stability. Knowing that he would have mostly young, talented pilots flying the plane, it was an easy compromise to make. Plus, the pilot could always bail out if he lost an engine and control of the plane because of it.

When it comes to our twin CL planes mission, having counter rotating props (as outlined in my prior post on this thread) is a worthwhile benefit. Given the low Reynolds numbers our size planes have and the very low speeds we fly at we would not see the gains that Kelly saw with the P-38. Therefore, we see the stability gains with no downside when we use CR props on our CL Twins.

Again, thanks for the cool photos. I have always liked the P-38. It was a pleasure to watch Lefty's P-38 race at Reno. I would have hated to watch one from the cockpit of a Zero in the 1940's! 

Regards,   

On the P-38 I seem to recall that they swapped the engines side to side in order to change the propwash signature on the stab - early models encountered then non-understood problem of compressibility and (among other things) were shedding tails (inconvenient!)and they were looking for solutions.

Hi Gang,
Great job Will ... but you knew that already.
The rotating "out" veresus "in" issue matters for ships that cruise and pull Gs in one direction only: positive G.
Yes, in upright cruise there are two benefits: 1) the direction of the spiral airflow is opposite that the wingtip vortex and they tend to cancel far enough behind the plane, which weakens and shrinks the vortex. 2) the spiral airflow on each side raises the effective AOA inboard, and reduces it outboard, kind of like washout. Any benefit would depend on the original design.

But that's not why I wanted to write.  You say you had "screeching" problems? Screeching is a problem most often seen on 3kW Pattern systems, and even then only when the currents are pushed very high. It appears to be an electrical noise problem (ironclad proof is a little tough on this one, as the problem tends to be sporadic and no one seems to have a storage oscillosope at the field!) . The high currents combined with long wiring on the motor side of the ESC or control cable proximity to any high current wiring confuses the circuits and routines that figure out the motor RPM and commutation position. The result is mis-timed power application to the windings. Sometimes this happens when too much current is applied to the motor due to strange saturation effects, and other times because the inductance of the windings causes voltage ringing after the commutation cycle ends..

As a general statement, almost all motors and almost all ESCs have shown this problem, but only in strange combinations of motor, ESC brand, current level, and installation. It's a wierd problem.

You have to love the benefits of no GP, though!

later,
Dean