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Old Mar 01, 2011, 01:15 PM
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Joined Nov 2010
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MiniMag climbs at 3/8 throttle - (noobie question)

I recently start flying planes (I fly heli’s) and I have a MiniMag running the Himax HC2815-2000 BL motor, with a 6x4 prop, 3s, and I have it set-up with ailerons. I set the CG as per the manual.

The issue I’m having is the when I try to fly level at anything more that 3/8 throttle the plane wants to climb. The elevator control surface appears to be level with the horizontal stab at neutral. I experimented adding elevator trim and moving the battery forward, which seemed to help somewhat. I still needed a lot of trim (maxed out) with the battery approx 1/2inch forward of the balanced CG position.

My question is what are the possible reasons for the plane to want to climb at that throttle position? Could it be that the combo of the prop and motor is just providing too much power for the plane and it just wants to take-off. It is kind of a pain to constantly compensating to bring the plane into level flight.
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Old Mar 01, 2011, 03:03 PM
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Midvale, Utah, USA
Joined Mar 2005
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Yes its caused by having too much power. To fix it you just need more downthrust.
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Old Mar 01, 2011, 03:05 PM
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glaros's Avatar
Greece
Joined Apr 2004
194 Posts
Yes, it's the lack of downthrust.

It is a common issue with overpowered (compared to the stock) Minimag.
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Old Mar 01, 2011, 03:41 PM
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Antarctica
Joined Dec 2009
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if you can't change the thrust angle easily, you could try and mix a bit of down elevator (I suppose that would be up elevator) into the throttle channel in a flight mode. However, that would slow the plane down a bit, and the airplane would balloon when you cut back the throttle quickly while moving at high speed. Or, you could try setting up a bit of negative flapperon (air brake?) to decrease the amount of camber of the wing, which would decrease the amount of lift generated by the airfoil. The final option I'll suggest is to raise the height of the wing at the trailing edge by putting a washer or something to that effect underneath the wing at the rear bolt. Any of those options should work for you.

I messed up the thrust angle on my minimag, and now I can't seem to fix it. That was a waste of a perfectly good airplane.
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Old Mar 01, 2011, 04:11 PM
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Would going to a smaller prop help? I do have some 5.5x4.5 props.

I will probably also try to mix in some elevator to compensate and see what happens. I also will go back to a balanced cg. My last landing with a nose heavy cg was a little rough.

Thanks to all for the advice.
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Old Mar 01, 2011, 04:37 PM
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United States, CA, Santa Barbara
Joined Nov 2009
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Quote:
Originally Posted by hudsonflyer View Post
Would going to a smaller prop help? I do have some 5.5x4.5 props.

I will probably also try to mix in some elevator to compensate and see what happens. I also will go back to a balanced cg. My last landing with a nose heavy cg was a little rough.

Thanks to all for the advice.
Not sure if you are using the stock motor and mount, but since their are only two holes, you could take the motor off, glue a small washer to the bottom face of the motor, then screw it back on. This will easily give you some down thrust.

You can experiment if you use a small drop of CA. The washer or spacer should be easy to remove and replace with something different.

Terry
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Old Mar 01, 2011, 06:41 PM
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i don't think the smaller prop would do much for you.

I've been doing some thinking, and I don't think I like the idea of changing the angle of attack of the wing with that washer. I think your best bet would be to mix a bit of the -ve flapperon with the throttle channel. Depending on how fast your minimag is, you may start with only, say, 3mm of travel at full throttle (to I would say a maximum of maybe 7mm), more if your plane still balloons after trying that.

I just remember that -ve flapperon is called spoileron. Duh. I don't know why I didn't come up with that before.

If you're good at understanding the cryptic language of transmitter programming, perhaps you could find some way of starting the throttle-spoileron mixing at, say, 35% of the throttle stick travel, or wherever on the stick the minimag starts to balloon.

The minimag used to be my go-to park flier before I messed up the firewall. The e-flite mini pulse xt fills that void. With the higher-kv 480-sized e-flite motor in there and an 11x7 (or 10x8 for when I'm feeling like speed not sport) up front, I can say it's absolutely my most enjoyable plane to fly so fa in my fleet. However, the minimag was much more forgiving in the event that gravity had had enough of the airplane's defiance, and decided to pull the airplane into the ground.
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Old Mar 02, 2011, 09:05 AM
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Clintonville, WI
Joined Jun 2008
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I've found that putting a 1/8" shim (like Velcro) under the rear edge of the wing helps quite a bit. It also has the benefit of keeping the wing straight and aligned. You don't need much, like a 3/8" wide piece, one on the wing, the other on the fuse. It gives enough change to the Angle of Incidence to the wing to make a difference. All MM tend to climb on higher throttle because of the wing incidence. I use full throttle to takeoff and reduce it at altitude which stabilizes the flight and the speed is enough to do loops and snap rolls.
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Old Mar 02, 2011, 12:34 PM
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Originally Posted by blinske View Post
I've found that putting a 1/8" shim (like Velcro) under the rear edge of the wing helps quite a bit. It also has the benefit of keeping the wing straight and aligned. You don't need much, like a 3/8" wide piece, one on the wing, the other on the fuse. It gives enough change to the Angle of Incidence to the wing to make a difference. All MM tend to climb on higher throttle because of the wing incidence. I use full throttle to takeoff and reduce it at altitude which stabilizes the flight and the speed is enough to do loops and snap rolls.
blinske - Great Tip! That's sounds like a pretty simple solution to try. I like the idea of it also holding the wing from twisting. I'm going to give that a try first. It seems like I could easily "go back" if needed.

I need to look into more on setting up flaperons and spoilerons. (I love the terminologies) It would be good for me to gain that understanding. I am flying with a JR 11x, so I would hope it has the programing capabilities.

Thanks again to all. I will post on how I make out.
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Old Mar 02, 2011, 07:02 PM
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BoonVegas, Indiana
Joined Dec 2005
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i put the velcro under the rear wing saddle also and it helped alot. quick fix !
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Old Mar 04, 2011, 02:47 PM
rcflyer
UK
Joined Jun 2010
848 Posts
Hi
Has anyone tried installing the tailwheel, I have the wire and the wheel but I was thinking that I need a bend in the wire before it goes into the fuse to act as a spring on a rough landing. What sort of bend will I need because otherwise the wire might go into the rudder foam.
Thanks
Jim
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Old Mar 05, 2011, 01:05 AM
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53859 Niederkassel, Germany
Joined Sep 2000
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Originally Posted by rcjim11 View Post
Hi
Has anyone tried installing the tailwheel, I have the wire and the wheel but I was thinking that I need a bend in the wire before it goes into the fuse to act as a spring on a rough landing. ...
Hi Jim,

you can do it exactly as per instruction manual. I have yet to see a rough landing where the tail wheel strikes first.

Jürgen
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Old Mar 05, 2011, 01:32 AM
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Midvale, Utah, USA
Joined Mar 2005
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Quote:
Originally Posted by rcjim11 View Post
Hi
Has anyone tried installing the tailwheel, I have the wire and the wheel but I was thinking that I need a bend in the wire before it goes into the fuse to act as a spring on a rough landing. What sort of bend will I need because otherwise the wire might go into the rudder foam.
Thanks
Jim

When I built a minimag for my brother, he wanted a steerable tailwheel. I built mine without, but his got one, and he never had a problem with it. Did it per the manual.
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Old Mar 05, 2011, 09:18 AM
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Clintonville, WI
Joined Jun 2008
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Did mine according to the manual and it works just fine. On my second MM, which was a rehab, I jury rigged a steerable tailwheel like the manual. Again, works OK.
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Old Mar 05, 2011, 06:17 PM
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Joined Oct 2006
329 Posts
I am in the process of putting together a mini mag with floats. I already own an ARC 28 47 3 motor. Weight is 110 grams and KV is 1500. Will the weight of the motor be too much?
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