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Old Dec 25, 2006, 10:34 AM
dmt
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Trim and CG Questions after flying my EasyStar a bit

Hello and Merry Christmas!

Christmas morning was almost no wind, so I took my new toy (Easy Star RTF) out for it's 3rd day of flying. I'm having a lot of fun flying it, but as I start to get some experience here, I'm wanting to deal with some issues that have been on my mind:

1) I have to fly with a lot of down trim. Almost max. It flies fine, but from what I read on the forums, a good glide or level flight at 2/3rds power should be approx. neutral. Do I need to move the CG forward? The plane seems to balance at 5mm forward of the rear of the spar box, as recomended. The battery pack is almost (but not quite) all the way forward in the fuselage.

A big concern of mine is that I used CA and Zap Kicker when mounting the empannage, and wasn't able to get it fully down and into position before the glue froze it. The result is that the angle of the horizontal stabilizer is essentially flat, as opposed to being pointed down somewhat as the instructions direct. I was worried that the tail would thus produce less tail down force, but the real-world response of my plane is that the nose would be too high with neutral trim.

Glide behavior and landing behavior is very docile. I'm pleased with the peformance as is too, but I would like the aircraft flying as well as possible, plus have more room for more down trim if conditions warranted (like I said, my trim throw is pretty much near max down for just normal flying).

2) I also have to use left rudder trim (even power off, but less so then), though the tail and everything else appears to be mounted straight.

3) Gliding around today near the base of a cloud, the nose of my plane suddenly lifted up, and then dropped down quite a bit (must have stalled). What's up with that? I'm guessing I ran directly into some lift (as opposed to a wing lifting, which is what I expected to happen based on reading about how to detect thermals)...
I circled around and flew back through the same area and it happened again.

Thanks for any help.
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Old Dec 25, 2006, 07:57 PM
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United States, WA, Yacolt
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some tips

..........
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Old Dec 26, 2006, 01:15 AM
dmt
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Quote:
Originally Posted by saucerguy
Your COG is too far back, you'll want it close to the leading edge of the wing, at least in the early stages of flight, move it per the manufactures specs after you get used to it being a bit nose heavy, it will glide, but not like a chuck glider and you should be able to center your trim at that point.

Having to trim it to the left is showing me that's something is out of alignment on the plane, you normally have to trim to the right, but then again, the trim elements in any plane are usually something you have to stay on top of from time to time regardless, I prefer having it manually trimmed out rather then making the radio do the work for you, this will maximize your control surfaces so you aren't limited what you can do, horizontal stab as you mentioned is case in point.
saucerguy, thanks.

I'll try moving the battery all the way forward (it's almost all the way forward now, but it could go a few mm farther in).

The tailfeathers look pretty durn straight, but upon re-examination, the vertical stab is perhaps canted a hair to the right [when viewed from the front, looking towards the tail]. I can't really decide if that would make it turn right or left though.

The EasyStar is a pusher design, so I thought that might explain the need for left rudder trim (as tractors require right rudder), but I don't have to dial out the left trim during a glide, so I guess it's a permanent feature of the aircraft as built (or perhaps the servos aren't truly adjusted for neutral? -- though they look welll-positioned to me).

I can see how one would want to fix the problems with proper CG and airframe alighnment, for best flight performance. I have to say though (while never having flown another EasyStar to compare it too), that it is flying like a dream as is. I gave it another four flights this morning and I'm really, really enjoying it. At one point I found some lift and was able to stay up indefinitely [with power off].

Anyway..., I will move the battery that little bit forward that it can go, and see how that effects things.
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Old Dec 26, 2006, 01:57 AM
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Quote:
Originally Posted by dmt
The tailfeathers look pretty durn straight, but upon re-examination, the vertical stab is perhaps canted a hair to the right [when viewed from the front, looking towards the tail]. I can't really decide if that would make it turn right or left though.
That's a feature with every ES I've seen and/or built. The home position of the tail assembly is slightly off vertical. You have to cant it ever so slightly when gluing it down to get it dead straight. That's also why I use epoxy on the tail... to fill in the slight gap when you cant the stabilizer to 'verticalize' it (for lack of a better term, I just make them up)...

Quote:
The EasyStar is a pusher design, so I thought that might explain the need for left rudder trim (as tractors require right rudder), but I don't have to dial out the left trim during a glide, so I guess it's a permanent feature of the aircraft as built (or perhaps the servos aren't truly adjusted for neutral? -- though they look welll-positioned to me).
The servos might be centered, but you just might not have the control surfaces in the same plane as the rudder and/or elevator prior to trimming it in the air. Another possibility is that the motor thrust line is slightly off the centerline axis of the plane.

That EasyStar is one NICE plane, ain't it?

Chuck
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Old Dec 26, 2006, 03:06 AM
dmt
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Quote:
Originally Posted by NoFlyZone
That's a feature with every ES I've seen and/or built. The home position of the tail assembly is slightly off vertical. You have to cant it ever so slightly when gluing it down to get it dead straight. That's also why I use epoxy on the tail... to fill in the slight gap when you cant the stabilizer to 'verticalize' it
I thought epoxy wouldn't bond to elapor, and we had to use medium CA with kicker? I guess not though, since you're saying you successfuly have used epoxy for the tail of your EasyStar. I wish I had known that, as the CA for my tail set before I could fully get the empannage down into it's intended position (thus my decelage (sp?) angle is lower than specified). Oh well, it flies!

Quote:
That EasyStar is one NICE plane, ain't it?

Chuck
Chuck, you ain't kidding. I'm somewhat embarrased to admit I bought my first RC glider kit 9 years ago (a complicated balsa kit), and I've [very]intermittently tried to get this hobby going me ever since then. It wasn't until I got this EasyStar last week that I finally was able to fly [with regular, repeated success] on my own, pretty much just like I'd originally envisioned.

Yesterday evening I was circling (gliding) high over a rice paddy, in still air, when two egrets on their way home came gliding over the field, diverted towards me and then broke off into a circling turn, momentarily joining up with the turning EasyStar. My wife was like, "They're responding to it!". After 3/4 of a turn they leveled out and continued gliding on. I had to keep circling so I didn't try to fly with them or anything. I didn't want to freak them out anyway -- they were doing their thing in the beautiful Yuletide dusk air, I was doing mine, and peace and goodwill towards all creatures reigned as we continued about our individual tasks.

It was so ****ing cool. It was like a dream.
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Old Dec 26, 2006, 10:37 AM
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Originally Posted by dmt
I thought epoxy wouldn't bond to elapor, and we had to use medium CA with kicker? I guess not though, since you're saying you successfuly have used epoxy for the tail of your EasyStar. I wish I had known that, as the CA for my tail set before I could fully get the empannage down into it's intended position (thus my decelage (sp?) angle is lower than specified). Oh well, it flies!
Hi dmt,

Yep, epoxy will work. I 'think' the manufacturer recommends against it because the claim is that it works, but somehow weakens with age? I have no idea, except to say that it's worked well for me. What I do is take a toothpick and poke shallow holes all over the two surfaces to be joined by the epoxy. This lets the epoxy seep into the holes acting as reinforcement, much the same way re-rod works for cement. The biggest benefit however is the extra time it gives allowing me to set it up perfectly in alinement. Besides, even if the claim that the epoxy bond with the foam is valid, the 'plugs' will certainly stay strong as anything.

Another thing I do is to use CA and kicker to glue the two fuse halves together. BUT.... I only put a drop every few inches along the halves. This way, on a less than ideal landing, the fuse halves will tend to separate at the glue joints, dissipating the kinetic energy of the crash by popping the glue joints, rather than having the energy be totally concentrated in one area of the fuse and crushing it.

Anyway, I'm no expert, but the above methods have worked very well for me.

Chuck
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Old Dec 26, 2006, 12:44 PM
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Here is my experience with the Easy Star:

I have built 3 Easy Stars. I used CA medium + on all 3. No kicker. Note all 3 are still flying.

The rudder and elevator on all 3 were slightly out of alignment. I simply gently twisted the body and got them to align. This makes me believe that the body is not molded correctly or the gluing process puts a twist into the body of the plane.

You will not always get the plane to fly the way you want it to fly by just moving the CG. You may need to put some mechanical trim in the controls. I like to mechanically trim my planes so I have full electronic trim available to me.

The Easy Star is a great plane and I hope you continue to enjoy it. bob
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Old Dec 26, 2006, 01:38 PM
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The ones flying locally all have had the c.g. moved forward.. 1 to 2 oz of lead.
I put mine on the battery.
And the rudder chord doubled.
It turns much better power off with the extra area.
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Old Dec 26, 2006, 05:50 PM
dmt
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NoFlyZone, Bob Breeze, Sparky Paul -- thanks a lot. I learned a lot right there in those three posts.
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Old Jan 09, 2007, 08:35 AM
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I used shoo-goo for assembly ( a trick I learned from assembling 3D EPP planes.) Shoo-Goo remains flexible when dry, dries slowly enough that you have plenty of time to position parts, and has plenty of "tack" to hold parts together.

It is pretty thick stuff, strong too. A little goes a long way!
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