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Old Apr 26, 2012, 03:39 PM
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Quote:
Originally Posted by derelicte View Post
no, you just need to flip the blades. the gyro works fine.

http://www.helifreak.com/showthread.php?t=183527
I'll concede that the gyro works fine, but flipping the blades won't do it, unless you reverse the motor (and then you need to reverse the tail).

The referenced forum discusses that reversing the motor is bad for it, so they put blades from a different heli that has reversed rotation.

===

If you're thinking, he's crazy, if I hold my V911 upside down, it blows "up", so flipping the blades would reverse the thrust.
But it hasn't. The thrust is still "down" relative to the heli.

It seems to have flipped to you, not because of the blades, but because flipping the motor makes it rotate the other way relative to your frame of reference.

Someone made a nice graphic a while back.

Here's a blade /
We're going to flip it over.
45 degrees |
90 degrees \
135 degrees |
180 degrees /

Props are designed to be oriented a certain way for efficiency.

Putting the tail rotor on your V911 backwards will still work, it just might be less efficient.
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Old Apr 26, 2012, 04:14 PM
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Canada, ON, Ottawa
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Quote:
Originally Posted by Killer Bee View Post
Or you could say it as... More pinion gear teeth equates to high head speed which means the motor runs at a lower rpm to maintain altitute. This would also mean greater performance/lift at max rpm. I guess my mistake was reading his repsonse as higher Motor rpm vs higher Rotor rpm which is what was actually said... The motor rpm would decrease for the same amount of lift. I think the 9958 is a worthwhile transplant motor for added performance.
When you say higher head speed, you mean higher max head speed. The operating head speed remains the same if the heli stays at the same height not going up or down.

The motor operating rpm would change depending on the gear ratio. That is correct. However the power requirement remains more or less the same to keep the corter hovering at the same height independent of motor rpm.

Motor rpm translates to back emf. A lower rpm means driving the motor at lower voltage but since the torque required would be higher to give the same power that implies higher current. (On a switching ESC, it probably means higher current but narrower pulses.) It depends on the ESC and motor winding which way they would work better.

The max. motor rpm would be limited by the battery voltage assuming the ESC and motor can handle the higher current. If they can we do have an advantage that it may deliver a bit more at pulling out starting with a lower motor rpm.

However do remember we are dealing with an unknown integrated brushed ESC and an unknown brushed motor. Higher current is not necessarily a good thing.

The FFF speed again is related to the max angle the cyclic can make assuming we have to maintain a level flight. In a way we cannot simply achieve a faster FFF speed by increasing the head speed unless we also allow the corter to gain altitude while going forwards.

We can do that but just be careful not getting too high and be blown away.
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Last edited by Wasp09; Apr 26, 2012 at 04:23 PM.
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Old Apr 26, 2012, 04:22 PM
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Quote:
Originally Posted by RicksterRC View Post
I'll concede that the gyro works fine, but flipping the blades won't do it, unless you reverse the motor (and then you need to reverse the tail)...
Have to reverse the motors. Some brushless ESCs can reverse direction of rotation on the fly.

It is less common for brushed ESC but can be done, the brushed motor driver for a servo is bidirectional. We need a bridge instead of a single transistor.
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Last edited by Wasp09; Apr 26, 2012 at 04:31 PM.
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Old Apr 26, 2012, 04:39 PM
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Joined Mar 2012
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D.I.Y. Do It Yourself.
This is so easy, it's dumb. Just Swap Top and Bottom Blades and put them on upside down. It works even on a Syma S107!
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Old Apr 26, 2012, 04:47 PM
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Inverted flying

Wouldn't it be possible to just use "backward" blades, made for a counter-clockwise rotor?
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Old Apr 26, 2012, 05:21 PM
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Quote:
Originally Posted by aidenXudfame View Post
Anyone have any advice?
You mean taking the blades off?

Takes off the 2 screws at the side, you would be able to pull the two blades apart.

The lever like connectors go in only when it is vertical. The shorter end connects to swash and the longer end connects to the flybar.

The main gear and flybar can be removed after removing the screws.

There are holes on the main shaft for screws, align the screw with the hole when you put main gear back on.
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Old Apr 26, 2012, 05:33 PM
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Quote:
Originally Posted by wavy View Post
D.I.Y. Do It Yourself.
This is so easy, it's dumb. Just Swap Top and Bottom Blades and put them on upside down. It works even on a Syma S107!
That would do it too on a co-axial if you mean swapping the blades mechanically yourself.

When I asked how selfclean and autoclean differed at a kitchen shop, I was told selfclean meant clean it yourself.
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Old Apr 26, 2012, 05:38 PM
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Quote:
Originally Posted by wavy View Post
Wouldn't it be possible to just use "backward" blades, made for a counter-clockwise rotor?
I know if you put he tail blade on backwards, it will blow the opposite direction so I see no reason the same can't happen with the main rotor.
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Old Apr 26, 2012, 05:44 PM
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New York
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as mentioned several times putting a prop on backwards, any prop (helii, plane, or hat), does not reverse thrust. it does however reduce efficiency big time unless its designed to reverse like s107 tail.


btw anybody need replacement motor? only $91.83. two sold already so better act quick!

http://www.ebay.com/itm/Main-Motor-F...item1c236ede5e
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Old Apr 26, 2012, 05:53 PM
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Quote:
Originally Posted by Killer Bee View Post
I know if you put he tail blade on backwards, it will blow the opposite direction so I see no reason the same can't happen with the main rotor.
Try that again with the main motor disconnected or main blade removed or use a bigger tail blade. Tell us what happens.
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Old Apr 26, 2012, 05:57 PM
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Must have got his currency convertor wired up backwards.
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Old Apr 26, 2012, 06:26 PM
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ah yes.. i see now that its actually only 56.99 quid. lol!
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Old Apr 26, 2012, 06:36 PM
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Quote:
Originally Posted by Killer Bee View Post
I know if you put he tail blade on backwards, it will blow the opposite direction so I see no reason the same can't happen with the main rotor.
Tail blades designed to blow in both directions (ie, like on the V911, 9958, S107, etc - the heli can yaw in both left and right directions) are shaped differently than the main blades are. Take a close look at the profile difference between the tail prop blades and the main blades.

Edit - V911 and 9958 tail blades are designed to blow in one direction ... doh!
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Old Apr 26, 2012, 06:39 PM
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HH: Only the S107 is designed to blow in either direction. The v911 and 9958 has tail blades that only blow in one direction.
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Old Apr 26, 2012, 06:40 PM
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New York
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Quote:
Originally Posted by Hayabusa Heli View Post
Tail blades designed to blow in both directions (ie, like on the V911, 9958, S107, etc
true for s107 but not v911. rotating in your hand at low throttle will show it either runs, runs fast, or just stops. you can also see by the shape that its designed for one direction only.

edit: oops... daryoon beat me to it. great minds think alike.
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