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Wing Dragon II CG question

Old 11-22-2010, 10:58 PM
  #1  
JackM
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Default Wing Dragon II CG question

I have a Wing Dragon III and had one good flight and one real ground pounder of a crash. I was amazed that the plane survived such a crash with so little damage!

I repaired the damage to the trailing edge of the wing and to the tail. Repairs were minimal and VERY LIGHT


I had never checked the CG but figured I should after making the the repairs. The CG is about 1" aft of where I think it should be.
  • Where should the CG be?
  • Should the tail boom balance level?
  • Should I add weight to balance the plane?
  • If I should add weight how much?
Assistance appreciated!

Jack

Last edited by JackM; 11-22-2010 at 11:35 PM.
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Old 11-23-2010, 01:59 AM
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quorneng
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I presume you mean a Wing Dragon 3ch (Rudder, elevator and motor speed).
You don't say where your CofG is but it should balance just about on the wing joiner, i.e. 2.75" back from the leading edge.
The WD is pretty tolerant (say +or- 1/4") on its CofG position.
When balancing the tail boom should be level.
It should be ok straight out of the box, mine was.
Have you modified yours in any way?
My 4ch WD started out standard but there is now not much of the original left.
There is a lot of info here
I hope this helps.
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Old 11-23-2010, 02:44 AM
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JackM
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Thanks for your reply! Yes, this is the 3 ch version. The reason I asked this question is that I had one good flight. Second flight I crashed. Third flight the plane acted squirley and crashed. After the crash, I replaced a few small pieces of foam and added a small piece of wood to the damaged trailing edge at the wing joint. The CG is now about 1/4" aft of the wing joining spar.

Being a beginner I wanted to have the plane in best possible trim before I try flying it again.

Jack
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Old 11-23-2010, 05:42 PM
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quorneng
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I would add a bit of nose weight to get it to balance right on the wing joiner. Any aft CofG will make it twitchy and less forgiving for a learner.
Does it have a NiMh battery and brushed motor or the later LiPo and brushless? The later set up is lighter and gives quite a bit more power.
My original wing and tail got pretty battered by the time I was good enough to fly and expect to take the model home undamaged but then learning to fly is what it was designed for. Keep at it.
This is how mine looks at the moment. You can just about see some of the original 2 year old bits.
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LiPo, brushless, new smaller wing with real flaps and a new tail yet it weighs 5oz less than the original.
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Old 11-23-2010, 05:53 PM
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JackM
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I think you're right about adding some weight in the nose to adjust CG. Although I am not a good flyer I understand a little about how an airplane flys and would have thought that the CG would be about 25% of the cord from the LE. The plane has the NiMh battery and brushless outrunner I think. It has a wall wart charger and no mention of safety in charging. It came with floats.

Your mods look great! Did you use the original receiver and tranmitter and just add a servo? Why is the horz stab raised?

Once I get a bit better at flying I want to convert to alerons. I bought it mainly for learning. I am also learning on Clearflight simulator which is a lot easier than repairing crashed planes!

Jack

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Old 11-23-2010, 11:19 PM
  #6  
quorneng
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Jack
Yes it still uses the original Receiver and Transmitter.
It has no undercarriage so the tailplane is raised to keep it from getting damaged on landing.
It also has no rudder so the 4 channels are elevator, aileron, speed and flaps.
Click image for larger version

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I modified the Transmitter to move the rudder function to a side flap knob control.
Click image for larger version

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All 5 servos are the tiny 3.9g type but the clever bit is the elevator servo which is buried in the fin.
Click image for larger version

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The wing has only 70% the area of the original, is just half the weight yet has better aerodynamics so it has both speed and endurance. It is fully aerobatic and glides well too. With the flaps fully down it lands really slowly.

So if you choose you can go a long way with a basic Wing Dragon.
Keep us informed with how you get on.
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Old 11-24-2010, 12:33 AM
  #7  
JackM
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Good idea to get the stab away from the ground! Do the flaps allow slow flight? I understand flaps for STOL but why in a plane sans landing gear? Inquiring minds want to know!

I plan to try mine on skis. We get lots of snow here and the parks are pretty quiet in the winter. I am wondering if cold effects batteries?

Jack
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Old 11-24-2010, 01:08 AM
  #8  
JackM
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I'm also interested in how to make a WDIII fly even slower. Larger wing? Thicker wing?

Jack
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Old 11-24-2010, 06:27 PM
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Jack
Provided you add the extra wing area without a proportional increase in weight it will fly slower but you might have to increase the tail sizes to maintain sufficient control.
Increasing the wing thickness may produce a bit more lift but it will increase the drag so need more power to fly.

The real answer to slower flight is always the same - reduce weight.

Compared to the original WD with its brushed motor your brushless is already quite a bit lighter.

Surprisingly the single heaviest item is the wing itself. My built up Depron wing is just over half the weight.

Your battery is the next heaviest item. A LiPo battery is also about half the weight of a similar capacity NiMh, so light in fact you may have to move things to keep the CofG correct. There is little point using a lightweight battery if you then have to add weight to get the balance right.

Finally comes the fuselage servos, their mountings and push rods.

Taken to extreme you get down to this.
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Exactly the same wing area and thickness as the original yet even with a LiPo of 1.5 times the capacity it still only weighs 16 oz. Compared to a standard Wing Dragon its performance is spectacular and flights of 30 minutes are quite possible.
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Old 12-18-2010, 11:34 PM
  #10  
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i got the WD III also lots of fun to fly

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