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Old Nov 25, 2010, 12:21 PM
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CG of HZ super cub?, also behavior question

OK, so I have a HobbyZone Super Cub.
I understand that wind makes flying more difficult, but are these symptoms just a result of wind?


Under full power with neutral controls and headed into the wind the plane gets into a cycle where it noses up, stalls, the ACT kicks in and kills the motor, the nose drops, the motor starts up and the cycle repeats itself.

The only cure I can find so far is to turn off the ACT and let the plane loop or turn it away from the wind.

Also the plane seems to have a bad glide angle for a beginner's plane to my thinking. I used to fly free-flights that would glide with a very shallow angle. This thing noses down quite steeply when the power is cut.

Where is the CG on this plane? I don't see it on the various websites I have found so far.

Thank you
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Old Nov 25, 2010, 12:47 PM
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USA, WA, Port Angeles
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2.25 to 2.5" aft of the leading edge of the wing.
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Old Nov 25, 2010, 12:51 PM
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Joined Jul 2008
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Turn off ACT and cut the wires to the sensor. ACT is the WORST technology ever to be put into a RC plane. The HZSC was my first ever RC plane and I could never fly it until I remove the ACT, anything that takes your control away even if it is supposed to help is just wrong.

The plane should glide in pretty well on its own almost as if it will land itself with you just steering it.
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Old Nov 25, 2010, 01:15 PM
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Compared to free flight the Cub is a rock. It is pretty draggy and has a so-so glide ratio. Something like the Easy Star is WAY better but in stock form does even worse in wind.

CG is not 'officially' published but set up stock is about right and about where you were told.

+ 1 on killing ACT. Garbage technology. This cannot be over emphasized.

What makes it difficult to fly in wind is the design, lack of power, lack of adequate control (ailerons) and MOSTLY lack of experience.
If you are new you should try to keep under 5mph. Intermediate can go up to 5-10mph. Higher wind is a recipe for cartwheels and breaking the tail off > an EXTREMELY COMMON OCCURRENCE.

Take a look at this video:
http://supercubclub.proboards.com/in...ad=3556&page=1
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Old Nov 25, 2010, 02:28 PM
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Quote:
Originally Posted by pantdino View Post
OK, so I have a HobbyZone Super Cub.
I understand that wind makes flying more difficult, but are these symptoms just a result of wind?


Under full power with neutral controls and headed into the wind the plane gets into a cycle where it noses up, stalls, the ACT kicks in and kills the motor, the nose drops, the motor starts up and the cycle repeats itself.

The only cure I can find so far is to turn off the ACT and let the plane loop or turn it away from the wind.

Also the plane seems to have a bad glide angle for a beginner's plane to my thinking. I used to fly free-flights that would glide with a very shallow angle. This thing noses down quite steeply when the power is cut.

Where is the CG on this plane? I don't see it on the various websites I have found so far.

Thank you
If you're flying it stock, tape two American Quarters to the small circular depression under the plane towards the tail. This will put the plane pretty near it's neutral balance point and it will glide like it's supposed to.

Chuck
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Old Nov 25, 2010, 02:42 PM
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Originally Posted by NoFlyZone View Post
If you're flying it stock, tape two American Quarters to the small circular depression under the plane towards the tail. This will put the plane pretty near it's neutral balance point and it will glide like it's supposed to.

Chuck
I checked the CG and it is about right-- with my fingers holding it at 2 3/8" behind the leading edge it hangs very slightly nose up but minimally so.

I considered adding weight to the tail, but won't this make my stalling under power problem worse?
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Old Nov 25, 2010, 03:11 PM
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Originally Posted by pantdino View Post
I checked the CG and it is about right-- with my fingers holding it at 2 3/8" behind the leading edge it hangs very slightly nose up but minimally so.

I considered adding weight to the tail, but won't this make my stalling under power problem worse?
Hi pantdino,

The first thing we need to do is figure out exactly where your C/G is at the moment. "About right" hardly ever works....

Unless a plane has what is called a 'lifting tail', then we can determine precisely where the C/G is by balancing it not on our fingertips, but on either a C/G machine, or even better and cheaper, a couple of pencils stuck into a 2x4 board. Put the pencils into the board so that the eraser end is up.

Now, what you want to do is look at the horizontal stabilizer of the plane and see whether it's dead level, angling down and forward, or angling down and rearward.

Do this with your plane, move it around on the pencils until it balances with the tail dead even and perfectly horizontal. Once it does this, then measure the distance accurately from the leading edge, back to the pencils. This will tell us where your C/G is presently.

It's my opinion only, that 90% of the crashes I read about here on RCG is either flying in too windy conditions, or having a plane that is horribly balanced.

Chuck
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Old Nov 25, 2010, 03:27 PM
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Dino,

When the little brother of the HobbyZone Super Cub (the Mini-Cub) came out, they had no mention in the manual or the literature of exactly where the Mini-Cub was supposed to be set for Center of Gravity.

I took it upon myself to determine this, and as you will see in my article below, I found that the plane flew very nicely just the way it came stock. It behaved like a trainer should, and flew fairly well.

So I took it home and set it up on my C/G machine and found that the tail was dead even and horizontal when the plane was balanced at exactly 1 3/8" from the leading edge. So I wrote my article, in hopes that anyone adding different batteries, etc to the Mini-Cub would be able to get the C/G where it's supposed to be.

I notice now that HobbyZone now publishes the C/G location as, you guessed it, 1 3/8" from the leading edge.

Center of Gravity for the HobbyZone Mini Super Cub

Go see this article, it explains it in pictures and shows what to look for.

Chuck
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Old Nov 25, 2010, 07:09 PM
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Originally Posted by NoFlyZone View Post
If you're flying it stock, tape two American Quarters to the small circular depression under the plane towards the tail. This will put the plane pretty near it's neutral balance point and it will glide like it's supposed to.

Chuck
Chuck,

I just zipped out of my family T-giving gathering to fly the plane and it definitely glides better with the 2 quarters there.

It seems to need some DOWN elevator trim under full throttle to keep the rate of climb / lack of stalling under control, but with no power it glides very nicely.

Actually it was so much fun I was just climbing a to about 200 feet then cutting the throttle entirely and just letting it glide down.

Thanks for the suggestion
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Old Nov 25, 2010, 07:13 PM
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Chuck,

I just zipped out of my family T-giving gathering to fly the plane and it definitely glides better with the 2 quarters there.

It seems to need some DOWN elevator trim under full throttle to keep the rate of climb / lack of stalling under control, but with no power it glides very nicely.

Actually it was so much fun I was just climbing a to about 200 feet then cutting the throttle entirely and just letting it glide down.

Thanks for the suggestion
You're very welcome! One of my Super Cubs still has those same two quarters affixed to it.

Down trim under full throttle is a characteristic of the stock Super Cub being balanced very near to it's 'sweet spot', or neutral point (to coin a term). This gives you the slowest and longest flights possible.... at the expense of it wanting to 'balloon up' under power up application.

By the way, the C/G of your plane should now be very close to 2 5/16" and it won't lose so much altitude when making turns now.

Chuck
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Old Nov 26, 2010, 06:03 AM
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All stock H.Z.S.C. is 2.25" back from leading edge of wing.
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Old Nov 26, 2010, 07:21 AM
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Wasaga Beach, Ontario
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Quote:
Originally Posted by pantdino View Post
OK, so I have a HobbyZone Super Cub.
I understand that wind makes flying more difficult, but are these symptoms just a result of wind?


Under full power with neutral controls and headed into the wind the plane gets into a cycle where it noses up, stalls, the ACT kicks in and kills the motor, the nose drops, the motor starts up and the cycle repeats itself.

The only cure I can find so far is to turn off the ACT and let the plane loop or turn it away from the wind.

Also the plane seems to have a bad glide angle for a beginner's plane to my thinking. I used to fly free-flights that would glide with a very shallow angle. This thing noses down quite steeply when the power is cut.

Where is the CG on this plane? I don't see it on the various websites I have found so far.

Thank you
The HZ SuperCub, like most positively stable airplanes, is designed to fly level at half throttle (well, most planes are in the 50-65 range.. the HZ SC is 50%).

A foreign concept to people unfamiliar with airplanes is that throttle is what you use to control altitude -your pitch (elevator) is used to control speed.

Generally the plane shouldn't stall under full power, it should just pitch down again if the speed get too low. But ACT (automatic-crash-technology) has been known to cause all kinds of unpleasant.
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Old Dec 24, 2010, 12:23 AM
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Littleton, CO
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You are unlikely to find what you are looking for if you keep beating your head against the wall with weight an balance. Consider modifying your decalage. Its as easy as adding a shim under your tail feathers and it worked great for me. See here.
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Old Dec 24, 2010, 07:59 AM
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Joined Jun 2004
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Sounds like a little downthrust in the motor would keep the plane from the wild climb rate. Should just do a shallow climb with full throttle after it's properly trimmed out.

Gord.
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