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Old Nov 25, 2012, 08:57 AM
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Joined Aug 2012
72 Posts
Question
450 build not lifting off

Hey guys ...I have just completed a 450 build and whats going on is Im having problem with getting it to lift off...

specs:

HK 401B Gyro
HK SS 50A ESC (set to soft spool up ...and normal set because I dont know the
number of poles on my motor brought over from a Rouge 500)
HXT 900 servos (4)

I set my throttle curve initially to 0, 25, 50, 75, 100 but since then 0, 30, 60, 80, 100

my pitch curve is ...45, 47.5, 50, 75, 100

what Ive been getting is a bit of vibration during spool ups ..but have looked at my head and tighten a few things up there with a bit of loctite after noticing a loosened top head nut. So what should I be looking for next ...is it right to adjust the thottle curve...without making any change in my Pitch curve? Hey guys any help and suggestions would be appreciated and by the way this is all set up with a spektrum DX6I Tx with Rx

Thanks in advance
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Old Nov 25, 2012, 09:20 AM
Axes & Blades-Cutlery & Helis
West Monroe NY
Joined Feb 2009
3,365 Posts
you need to adjust the swash heigh so at max throttle the blades have a 10 deg pitch (or more, 10 deg is good for a 1st timer).

disconnect the motor leads (at least 2 of them) and fire up the heli and tx, put the throttle to 1/2 and the blades should be 0 pitch, if you hit the idle up switch you should get ~-10 deg.

you can set the throttle curve independant of the pitch curve and vice versa, you curves look good.

Soundsl like you need to do the mechanical setup, it also sounds like you are getting close to a flying heli so don't stop now

My suggestion is to go to check out finless bob's build vids on helifreak. Watch all the 101 stuff, it will explain all the basics of setting up a CP heli, be sure to watch the specific vid on your heli/clone.

you can find a specific build here, so if you are building a TREX 450 Pro, goto the pro build
http://www.helifreak.com/forumdisplay.php?f=60

Here are the basics
http://www.helifreak.com/showthread.php?t=41692

good luck
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Old Nov 25, 2012, 09:27 AM
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Aachen Germany
Joined Dec 2007
2,046 Posts
Pitch curve on your DX6i is only relative to how the mechanics are set up. You need to put a pitch-gauge on your blades and check the pitch of the blades over the range of your pitch curve. For training (non-3D) reduce the range of your collective. Center stick (lift off) should be +3 to +4 degrees. Low stick -2 degrees and high stick +8 degrees will give you all the collective control you need. If you are unable to get any positive pitch check the connecting rods to the blade holders. Also make sure the leading edge of the blades (thickest part) are facing the direction of rotation.

captJac
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Old Nov 25, 2012, 10:39 AM
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Joined Aug 2012
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Quote:
Originally Posted by ewoodcox View Post
you need to adjust the swash heigh so at max throttle the blades have a 10 deg pitch (or more, 10 deg is good for a 1st timer).

disconnect the motor leads (at least 2 of them) and fire up the heli and tx, put the throttle to 1/2 and the blades should be 0 pitch, if you hit the idle up switch you should get ~-10 deg.

you can set the throttle curve independant of the pitch curve and vice versa, you curves look good.

Soundsl like you need to do the mechanical setup, it also sounds like you are getting close to a flying heli so don't stop now

My suggestion is to go to check out finless bob's build vids on helifreak. Watch all the 101 stuff, it will explain all the basics of setting up a CP heli, be sure to watch the specific vid on your heli/clone.

you can find a specific build here, so if you are building a TREX 450 Pro, goto the pro build
http://www.helifreak.com/forumdisplay.php?f=60

Here are the basics
http://www.helifreak.com/showthread.php?t=41692

good luck
Hey...thanks lots....I will do as you suggested and check this out.....again your input is very much appreciated
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Old Nov 25, 2012, 10:45 AM
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Joined Aug 2012
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Quote:
Originally Posted by CaptJac View Post
Pitch curve on your DX6i is only relative to how the mechanics are set up. You need to put a pitch-gauge on your blades and check the pitch of the blades over the range of your pitch curve. For training (non-3D) reduce the range of your collective. Center stick (lift off) should be +3 to +4 degrees. Low stick -2 degrees and high stick +8 degrees will give you all the collective control you need. If you are unable to get any positive pitch check the connecting rods to the blade holders. Also make sure the leading edge of the blades (thickest part) are facing the direction of rotation.

captJac
Hmmm....ok....thanks for your input...I did do the blades using a gauge....so you say at mid stick I should use +3 or +4 ...I will try this too..but Im a bit confused on what you mean as far as Low stick.....-2 degrees ...so does this mean below mid?

again ...thanks for you input...its appreciated
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Old Nov 25, 2012, 12:34 PM
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Aachen Germany
Joined Dec 2007
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Quote:
Originally Posted by cantyman View Post
Im a bit confused on what you mean as far as Low stick.....-2 degrees ...so does this mean below mid?
Low stick is referring to the lowest position on the left stick (collective) on your DX6i. 3D requires mid stick (center position) is 0 degrees - everything below center position is negative pitch - and everything above center postion is positive pitch. For beginners I advocate a more conservative approach - - and use very little negative pitch as this has the tendency of pancaking your heli in the ground if you panic and slam the collective down. Have a read of the 3D is NOT for everyone thread.
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Old Nov 26, 2012, 12:15 AM
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Australia, VIC
Joined Dec 2011
1,107 Posts
Beginner

Starting out , learning ...

Last thing you want is 0 pitch @ 0 throttle : Why ?

When starting out , to get out of trouble or to end a bad situation it pays to learn to cut the motor by throttling back [ less damage that way ]

This would result in 0 or neg pitch [ very bad as the heli tends to fall like a stone ] ..

So you want pitch @ zero throttle , maybe 5 inches ...

So where it becomes a balancing act is , Pitch at 0 throttle , rotor head speed , pitch curve ... Start with 5 inches of pitch @ 0 throttle , then adjust the pitch curve to get the right rotor head speed ...

Most people ?? [ really ? ] I dont know , but is half throttle a good point for the heli to lift off the ground ?

Im comfortable around half throttle [ stick ] for lift off ...

I also try to find the lowest head speed , that the heli will hover stable .. [ Were not trying to 3D ]

+ STABILITY !

Do you want the heli to be as stable as possible ?

Lower head speed = More stable ..
More flybar weight = More stable ...

High head speed = Responsive [ read as less stable - moves quickly ]
Less flybar weight = More responsive - moves more quickly

Having a very fast moving [ in any direction ] heli is the last thing a Noob needs .
Perhaps I should re - phrase , rather than fast moving - I should say - its fast to take off in any given direction due to instability ..

Something much wanted for 3D or sport flying , but the opposite applies for Noobs , you dont want a responsive helicopter , you want to dull it down , take of the edge - so you have time to respond to the helicopters inherent instability .

You want to turn a hyper kitty into a sleepy cat ...

Easy way = More flybar weight , slower rotor head speed , and even slightly longer rotor blades ...

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Old Nov 26, 2012, 06:48 AM
Axes & Blades-Cutlery & Helis
West Monroe NY
Joined Feb 2009
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Quote:
Originally Posted by old4570 View Post
Starting out , learning ...

Last thing you want is 0 pitch @ 0 throttle : Why ?

When starting out , to get out of trouble or to end a bad situation it pays to learn to cut the motor by throttling back [ less damage that way ]

This would result in 0 or neg pitch [ very bad as the heli tends to fall like a stone ] ..

So you want pitch @ zero throttle , maybe 5 inches ...

So where it becomes a balancing act is , Pitch at 0 throttle , rotor head speed , pitch curve ... Start with 5 inches of pitch @ 0 throttle , then adjust the pitch curve to get the right rotor head speed ...

Most people ?? [ really ? ] I dont know , but is half throttle a good point for the heli to lift off the ground ?

Im comfortable around half throttle [ stick ] for lift off ...

I also try to find the lowest head speed , that the heli will hover stable .. [ Were not trying to 3D ]

+ STABILITY !

Do you want the heli to be as stable as possible ?

Lower head speed = More stable ..
More flybar weight = More stable ...

High head speed = Responsive [ read as less stable - moves quickly ]
Less flybar weight = More responsive - moves more quickly

Having a very fast moving [ in any direction ] heli is the last thing a Noob needs .
Perhaps I should re - phrase , rather than fast moving - I should say - its fast to take off in any given direction due to instability ..

Something much wanted for 3D or sport flying , but the opposite applies for Noobs , you dont want a responsive helicopter , you want to dull it down , take of the edge - so you have time to respond to the helicopters inherent instability .

You want to turn a hyper kitty into a sleepy cat ...

Easy way = More flybar weight , slower rotor head speed , and even slightly longer rotor blades ...

you are confusing stability with agility. A high HS will make the heli a bit more touchie, this is agile, how fast the heli will respond/roll/pitch, a high HS will also increase stability due to gyroscopic effect, it takes more to make the disk move. That is stability, the two are easy to confuse but they are different.

Myself, I like a higher HS, I use some expo to keep it tame around center stick.

cantyman, I actually lke your pitch/throttle curves better than those suggested by CaptJac, those are fine but I tend to use the curves you wrote initially +/- around the center throttle curve (ie sometimes my mid point is 70, on rare occassion I will use 50 or 55).

You should have had a chance to go over the mechanical setup, what have you found?
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Old Nov 26, 2012, 06:31 PM
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Joined Dec 2011
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Hmm

Quote:
Originally Posted by ewoodcox View Post
you are confusing stability with agility. A high HS will make the heli a bit more touchie, this is agile, how fast the heli will respond/roll/pitch, a high HS will also increase stability due to gyroscopic effect, it takes more to make the disk move. That is stability, the two are easy to confuse but they are different.

Myself, I like a higher HS, I use some expo to keep it tame around center stick.

cantyman, I actually lke your pitch/throttle curves better than those suggested by CaptJac, those are fine but I tend to use the curves you wrote initially +/- around the center throttle curve (ie sometimes my mid point is 70, on rare occassion I will use 50 or 55).

You should have had a chance to go over the mechanical setup, what have you found?
Hmmm , agility / stability ...

Noo , ill go with stability .. Why ?

Why , lets examine ..

Lets say you get the heli into a perfect hover ...
And it takes 2 or 3 seconds to start drifting , now that agile heli will take all of one second to accelerate and move quite a few feet , and once its moving , another second and it will have quite a bit of speed ..

Now depending on your circumstances , skill , etc and where your flying ..
That 1 to 2 seconds might see your heli in a fence , tree , clothes line etc .
Or in the ground ..

Now lets dull it down with slower head speed . more flybar weights and slightly longer rotor blades ..

You now might see hands off hover around 5 to 10 seconds [ mine can do this ] also when it begins to drift , it drifts slowly , really slowly .. So slowly that if it drifts in the right direction , you just let it go as it only drifts within a certain space .

So it will hold a certain hover area , maybe 5 square meters .. [ need to explore this more ] , but it looks like you can stabilize a 450 to a certain level or area of drift .. [ School is over - so lots of things to test ]
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Old Nov 28, 2012, 02:34 PM
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Joined Jan 2012
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Re: No lift

I had that same problem not so long ago.
I whould spool up to full power and no lift,and as i spooled down got to about 25% throttle it tried to lift. For a bit i was thinking what was causing it, when it hit me. I have the asilron and pitch conectors on the RX backwards.When i reversed the two conectors BANG the heli got airborn.That CHOULD be the prob that you are having.Another problem chould be that your ESC might not be high enough (amperage)
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