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Old Jun 03, 2011, 11:11 AM
blk822 is offline
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Well I think I will maiden my plane today. The weather is PERFECT today ,so after work it's to the field. Wish me luck this is my first glider.
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Old Jun 03, 2011, 11:13 AM
maddawg1 is offline
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Take your lawn chair kick back and injoy the flight
Old Jun 04, 2011, 04:36 AM
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Hey,

I maiden my pheonix this morning, everything is good except for one, it tends to dive whenever im on neutral. I had to trim the elevator down around 70percent to get it glide whenever im on neutral.

Im using 2200mah batt with 30gram of weight at the tail to get the COG perfect.

But with perfect cog, i still get a dive on neutral, i have to contantly have an elevator input to glide it nicely.


Help.
Old Jun 04, 2011, 07:45 AM
F-111 John is offline
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Quote:
Originally Posted by Slapshock View Post
Hey,

I maiden my pheonix this morning, everything is good except for one, it tends to dive whenever im on neutral. I had to trim the elevator down around 70percent to get it glide whenever im on neutral.
To me, a tendency to dive would mean you have to trim the elevator up, not down.

Check the incidence of the wing and tail. Are the bottoms of the tail and wing parallel to each other?
Old Jun 04, 2011, 08:59 AM
skyhawk newbie is offline
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Quote:
Originally Posted by Slapshock View Post
Hey,

I maiden my pheonix this morning, everything is good except for one, it tends to dive whenever im on neutral. I had to trim the elevator down around 70percent to get it glide whenever im on neutral.

Im using 2200mah batt with 30gram of weight at the tail to get the COG perfect.

But with perfect cog, i still get a dive on neutral, i have to contantly have an elevator input to glide it nicely.


Help.

I set CG @ 70mm back from LE, using 2200mAh Li-Po , gliders straight .
No weight add to tail....
..
Old Jun 04, 2011, 11:57 AM
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How did you do that i need to add weight to get cg right.

Yeah what i mean was trim the elevator up...

Whats seem to be the prob? I
Didnt see any major visible mishaps on my plane...
Old Jun 04, 2011, 01:03 PM
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Originally Posted by Slapshock View Post
How did you do that i need to add weight to get cg right.

Yeah what i mean was trim the elevator up...

Whats seem to be the prob? I
Didnt see any major visible mishaps on my plane...
I'm using a Turnigy 2836 1000kv motor with a Alloy spinner , may be heavier then a stock motor ?

remove the tail weight , Try moving your battery forward . .
( for ever Oz @ the Tail = 8 Oz on the nose , well that what I've been told )
Old Jun 04, 2011, 04:18 PM
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Quote:
Originally Posted by skyhawk newbie View Post
( for ever Oz @ the Tail = 8 Oz on the nose , well that what I've been told )
It depends on the length of the "lever" - the distance between the CoG and where the weight is located.

For example, if 10g of ballast is placed in the tail 50cm behind the CoG, the new "moment" (torque) could be counteracted by adding 100g precisely 5cm in front of the CoG, or 50g at 10cm in front.

There is no one-size-fits-all rule. The moment consists of the weight times its distance away from the axis/fulcrum. If the distance is 8 times greater to the tail wieght, then the ratio will be 8-to-1 like you said. For planes with a shorter tail boom, it may very well be 6-to-1 or 5-to-1, or whatever.
Old Jun 04, 2011, 06:37 PM
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Originally Posted by H2SO4 View Post
It depends on the length of the "lever" - the distance between the CoG and where the weight is located.

For example, if 10g of ballast is placed in the tail 50cm behind the CoG, the new "moment" (torque) could be counteracted by adding 100g precisely 5cm in front of the CoG, or 50g at 10cm in front.

There is no one-size-fits-all rule. The moment consists of the weight times its distance away from the axis/fulcrum. If the distance is 8 times greater to the tail wieght, then the ratio will be 8-to-1 like you said. For planes with a shorter tail boom, it may very well be 6-to-1 or 5-to-1, or whatever.
True . .

.
Old Jun 05, 2011, 12:28 AM
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I dont quite understand, my problem is now that i have to add 30g weight at the back to get the CG right (i think my motor quite heavy - using EMAX 2218 1100KV motor)

with the CG perfectly right, when im on neutral, my glider did not glide, instead its dive, i have to trim my elevator up to get it glide....

this would cost an energy and a lesser flight time.

pls advise, thanks.
Old Jun 05, 2011, 06:05 AM
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Anyone could clarify to me?
Old Jun 05, 2011, 07:11 AM
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Quote:
Originally Posted by Slapshock View Post
I dont quite understand, my problem is now that i have to add 30g weight at the back to get the CG right (i think my motor quite heavy - using EMAX 2218 1100KV motor)

with the CG perfectly right, when im on neutral, my glider did not glide, instead its dive, i have to trim my elevator up to get it glide....

this would cost an energy and a lesser flight time.

pls advise, thanks.
There are other reasons why the plane might adopt a more nose-down posture. The most obvious would be the angle of incidence for the horizontal stabilizer, and possibly even the main wing.

If the leading egde of the Hstab is pointing slightly upwards, perhaps because of the way the bolts have been tightened or because something is glued out of alignment, the tail of the plane will generate abnormal amounts of lift, thus pushing the nose down - even though the CG might be spot on.

When you're doing your CG tests, have a look at the angle between the Hstab and true horizontal. It's not always simple to gauge, but when the plane is precisely balanced on its design CG the Hstab should point ever-so-slightly downward, or be absolutely horizontal. Having it point upwards to any degree will cause exactly the symptom you're describing.
Old Jun 05, 2011, 07:25 AM
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I agree with H2SO4. Check your stabilizer, it is the main reason for the plane to be out of balance......
Old Jun 05, 2011, 09:32 AM
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Sorry for my ignorance,

What are Hstab?
Stabilizer, do you mean the tail horizontal parts?
Old Jun 05, 2011, 09:37 AM
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Quote:
Originally Posted by Slapshock View Post
Sorry for my ignorance,

What are Hstab?
Stabilizer, do you mean the tail horizontal parts?
Yes. The bit that the elevator is attached to.


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