Multiplex Easy Star - thread 7 - RC Groups
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Jun 03, 2004, 01:23 PM
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Multiplex Easy Star - thread 7

Wow we are starting thread 7 already. Maybe we should start a theme or something....... like who has the worst busted up Easy Star that still flies !!
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Jun 03, 2004, 01:40 PM
sensitive artsy type
Treetop's Avatar
Here is a link to Multiplex Easy Star - thread 6:
Jun 03, 2004, 01:40 PM
the journey is the reward
Hammer Head's Avatar
Thread 7!

Jun 03, 2004, 01:55 PM
sensitive artsy type
Treetop's Avatar
Spash, in case you missed my last post, are you saying trimming the plane is opposite from Detract's posted drawing. I remember my first flight, and the plane was zooming under power, (trying to fly straight up) and you advised me to move the CG, or Battery pack forward. This made the problem worse. On the third flight I moved the CG back and the zooming became less and controllable. The EZ should try to climb some under power to make it stable, and a little elevator adjustment to control the climb is OK, then, with power off, it should glide like a glider, not have the nose try to come up. I am still looking for the magic compromise, but slight variences in trim and battery pack location seem to have a large effect. This makes the process a little tedious. Getting good climb rate, and a long glide path. The EZ is different from say a Slow Stick, in that with the SS, you pretty much fly around with power all the time, but with the EZ, it is like two planes in one. This CG thing is very confusing on this thread. tt
Jun 03, 2004, 01:58 PM
ziege's Avatar
Responding to something from the previous thread...

Originally Posted by treetop
Splash, that is as clear as the mud on your EZ stars nose. tt
No, I think it makes perfect sense (assuming you are referring to the dive trim fine print translation).

You (I think it was you...many people chimed in) pointed out that if the nose is heavy, the tailplane must be trimmed to have downward lift to maintain level flight. As the plane moves faster (in a dive or under power) the increased airflow increases the (negative) lift, lowering the tail yet further.

The fine print was saying that if you have the control surfaces neutral (no negative lift on the tailplane) it will behave as I originally described. This too makes sense... if the controls are neutral and the CG is behind the wing's center of lift, the weight will push the back of the plane down. Of course, that happens whether you are in a dive or not.

I've always done my balancing by trying to minimize the trim required....I saw the dive trimming thing and thought it looked cool so passed it on. Having done a bit of googling on it now, it looks like I put my foot in a contentious area.

FWIW: I checked the TX manual I was vaugly said the test should be with neutral trim. Details.
Jun 03, 2004, 02:13 PM
Registered User
tt- the other issue is not all Easy Stars are the same. The recent one I just built flew better with the CG a lot more forward than the others I have. The battery had to be moved a inche or so forward compared to the other Easy Stars. All this was done using my original set of wings that I had flown the others with. So, the only thing that had changed was the fuse.

I think it's all due to foam density variations. Also, I assume many different molds are probably used as the Easy Stars are mass produced. Slight variations in the molds can/could cause diffeneces in the flight charteristics.

I crashed the ES#4 twice until I figured it all out. After I dialed the CG in the ES flew fine with no further problems.

There is no such thing as a free lunch. The ES won't fly neutral with one trim setting for both powered and un-powered flight. Slight adjustments to the trim button should be all the that is needed in no wind conditions.
Last edited by Zoomzoom; Jun 03, 2004 at 02:18 PM.
Jun 03, 2004, 02:28 PM
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Treetop's Avatar
ZZ, given the floppy nature of the Elapor (and thank goodness for it) I think how it is stored is also important. When I last flew the EZ, it pulled to the right a little, which was a new feature. I noticed later, should have checked before, that the stabilizer was kicked up a bit on the right side towards the tip, no cracks or damage, just think it may have sat leaning against that tip for a couple of days. I think the nature of the EZ, is one that given the amount of crashing with us newbies, and the elapors un-rigid nature, one has to expect to find little differences from time to time and just adjust for them. This beats having a bag of foam dust to bring home. I must also look to storing the EZ in a balanced manner.

Here is a quote from the EZ instruction book about the CG, I'm sure it is a typo, but reading this as a newbie could only add to the confusion.

"If the model is tail-heavy, fix the ballast at the fuselage nose; if the model is tail-heavy, attach the ballast at the tail end of the fuselage."
Jun 03, 2004, 02:32 PM
ziege's Avatar
What was the typo??? Should it have read "...fuselage nose; if the model is STILL tail-heavy..."?

Just kidding.
Jun 03, 2004, 03:14 PM
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Treetop's Avatar
Well this is my opinion on the matter. The instruction manual says the EZ should after hand launching, under full power, "Your model should climb out and directly away from you at a shallow angle and with the wings level."

If like on my Easy, it zooms, tries to go straight up under power, the CG is too far forward. Simple enough, and not just my opinion. It also interrelates with the upthrust on the motor, but this can't be easily adjusted. The other possible correction would be wing incidence, which is what adding downtrim on the elevator changes.

That is why in a dive test, it says if the plane zooms up, kopflastig (add weight to tail).

The question comes here, when trimming out, what is best, and what is best may be trimming the elevator down just a bit, like 1mm and moving the CG forward just a bit. But this is where the experimenting comes in.

Here is Patrick's great post on the matter.


As a generality, if your plane has its CG in the right place then it should fly correctly with trims and control surfaces neutral.

Put it this way. If you take your EZ* to altitude and chop the motor, then trim it for the glide, then bring it in and land it WITHOUT touching the trims. It will tell you a story.
If you look at the tailplane and find the elevator is down you will know that the tailplane is telling you that it is having to lift the whole tail. In other words it is tail heavy. If the elevator is up some then it's vice versa.

Add or remove weight in the nose to correct the CG. until the plane glides well with everything centred. Only then will you experience "Hands Off" flight.

NOTE. If the motor is correctly glued in the motor housing, the thrust line of the EZ* passes thru the CG and therefore has negligible effect on the behavior under power. In practice the EZ* is set up by the manufacturer for a gentle climb under WOT as this is safest for beginners.

Cheers. Patrick.

The fact that my EZ does not climb gently under WOT is the problem. Maybe I can adjust the motor upthrust to be less. With no Upthrust the motor being above the wing would push the plane downward, causing it to dive. With too much upthrust the nose would go up, imagine the motor on the tail (as it is aft of the CG) and if it was faced straight up (the prop pushing air up), the tail would go down. If it was faced straight down the tail would go up.

The fact that my plane glides great, and I only have a problem under power, makes me think it might be the thrust incidence.

Patrick, if you want to help here by addressing this zooming problem, I would appreciate your good advice, tt
Last edited by Treetop; Jun 03, 2004 at 03:28 PM.
Jun 03, 2004, 03:46 PM
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staib's Avatar
Hi everyone. This 7th thread seems a good place to leap out of lurk (and read) mode and introduce myself :-) I have taken tomorrow off work to go and buy my first Easy Star ! It's been ages since I last flew an RC plane, but I was *quite* good at it, having last flown a powered Wot 4 ten years ago (UK readers may recognise that one). I think its the shape of those wings and the knowledge that the Easy Star design is right that draws me to this little baby!

Thanks to you all for sharing your enthusiasm and experience - without this I would never have retaken the plunge :-)


PS - Any last minute advice on "extras" to buy?! - LOL
Jun 03, 2004, 03:51 PM
EasyStar pilot
Detract's Avatar
Maybe two bottles CA!?

But first, welcome to the "never ending story"...
Jun 03, 2004, 03:53 PM
the journey is the reward
Hammer Head's Avatar
Getting out of the Office this afternoon (I work at home) to do a bit of EZ flying. Looks like a good day to catch some thermals so it is off to Mr. Hawks field area (see end of thread 6 for details).

I had a canopy left over from EZ I, so I have set that all up. I will, however, put an elastic around the canopy and fuse just in case Mr. Hawk should return and go for the EZ eye again.

Keep em up there!

Jun 03, 2004, 03:54 PM
Registered User
I think we are beating the CG topic to death.

tt- if your plane glides fine and noses up hard under power......... it's tail heavy.

Too much up or down trim correcting for CG causes a lot of parasitic drag on the ES and it'll fly like crap. All mine have been very sensitive to trim settings during climbouts. You can make significant changes in the climb rate with the trim without changing the angle of attack.

The bottom line is you want the elevator as neutral as possible.
Jun 03, 2004, 04:02 PM
Registered User
staib - If you have the extra cash I would consider getting LiPo batteries. They are lighter and will give you longer flight times(s).

HH - Your a man after my own heart flying with hawks, eagles and such. You need to get a camera !!! Good luck and fly safe......

P.S - You can see a few chunks of foam hanging off of my wing in the picture. Just a little torny bush rash.
Last edited by Zoomzoom; Jun 03, 2004 at 04:34 PM.
Jun 03, 2004, 05:02 PM
Registered User
pino360's Avatar

What the.......

Hey you guys...
Slow down please thread 7 all ready and I havent maidened the EZ* yet? and the weather here has been great today little or no wind blue sky and still no battery compartment for the Tx....
Weather tomorrow? Rain.....
But maybe? I hope that the compartment arrives and the rain will pause just a little so I cuold get a first flight.
Been "savaging" a little this afternoon just to do a little R/C....


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