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-   -   The Apprentice 15e.... guess what.... (https://www.wattflyer.com/forums/showthread.php?t=75973)

xmech2k 06-07-2015 09:44 PM

Flutters at part throttle? I've heard of prop vibration causing AS3X to freak out. Check prop balance, (Do you have a prop balancer, like this one, for example?) and I don't know if you replaced the motor after that last crash, but look real close for a bent prop shaft.

Yes, I know, generally, the vibration should get worse and worse at higher throttle. Perhaps it's a harmonic thing affecting the rx though.

birdDog 06-07-2015 10:05 PM

Heck, if nothing else, even one of these $1.50 gadgets. Rigging up a stand with two leveled razor blades makes it work even better.

http://cdn.hobbyking.com/hobbyking/s...ncer-14927.jpg
http://hobbyking.com/hobbyking/store..._Balancer.html

I know people who brag about never having balanced an e-prop. If they only knew.

theapplepi3.14 06-08-2015 01:36 AM

Right now we are doing bad engineering. We are trying to get him to replace everything in the plane one by one until the plane works. We may or may not learn what caused the problem this way, and it will happen a lot faster either way if we don't do this. What we should be doing is changing the Rx to a standard one because we are pretty sure that is the problem (but if this issue has taught me anything it is don't be too sure). If that flies fine we need to change things BACK one by one until it DOESN'T work so that he saves money, and time, and so that we get a conclusive result out of this. Have you considered that it makes more sense to make 100% sure the AS3X is the problem before trying to balance the prop, or beef up the plane, or replace random parts? All he needs to do is buy a cheap Rx, try it out, and when that works he has A) a working plane, B) a spare Rx, C) some money in his pocket D) the ability to figure out the problem

Sorry for the length of this comment, and the bluntness of my remarks. I don't like sugar coating my opinions, but my intention was not to insult, although reading this in a certain light might make it seem that way.:eek:

birdDog 06-08-2015 01:48 AM

All props should be and in my experience need to be balanced. Besides, I like the smell of clear lacquer!

solentlife 06-08-2015 08:24 AM

Balancing a prop is basic item and should be done anyway.

I do admit that on flight line - I fit without balancing, but at home I remove and sort it.

I used to sand to balance or add lacquer ... but now on electrics - I use clear tape strip folded over leading edge. Same method as helicopter blades. This prevents any slight change in blade form.

My balancer - I have two based on the shaft and two cones shown earlier. One is the helicopter one without frame as shown earlier post, my other is same but with small magnetic frame. Both simple, able to balance smallest to big props easily. The plain shaft cone job - I took a piece of wood, screwed two shelf 90deg brackets to it to rest the shaft ends on.

I must tend to agree with another about changing too many things. Elimination to cure a problem should in theory be - replace one item - test. If not cured, put back original part and change next item - test .... keep doing this till cure is found.
But whatever - for newcomers to the hobby - it means costs. For oldies like me - we have spare gear on bench ....

Nigel

xmech2k 06-08-2015 11:14 AM

IIRC, we brought up the rx long ago. He didn't replace it. We're along for the ride!

solentlife 06-08-2015 02:15 PM

Just a comment about out of balance props and effects.

I have trouble thinking an unbalanced prop would cause flutter ... take my glow powered jobs ... when engines running and all is balanced - the model is still vibrating ... surfaces vibrating on the ground.
Surely you would need a serious difference on the prop balance to cause flight flutter ? Especially that E props are lighter and less liable to vibration etc.
I did have a prop cause me trouble on one E model ... part of a blade got clipped on take-off and I cont'd to fly .... yeh I know Silly ! When I landed - the motor mount and firewall was separating from the fuselage but flight was fine.....

Nigel

woodmangler 06-08-2015 03:57 PM


Originally Posted by solentlife (Post 975918)
Balancing a prop is basic item and should be done anyway.

I do admit that on flight line - I fit without balancing, but at home I remove and sort it.

I used to sand to balance or add lacquer ... but now on electrics - I use clear tape strip folded over leading edge. Same method as helicopter blades. This prevents any slight change in blade form.

My balancer - I have two based on the shaft and two cones shown earlier. One is the helicopter one without frame as shown earlier post, my other is same but with small magnetic frame. Both simple, able to balance smallest to big props easily. The plain shaft cone job - I took a piece of wood, screwed two shelf 90deg brackets to it to rest the shaft ends on.

I must tend to agree with another about changing too many things. Elimination to cure a problem should in theory be - replace one item - test. If not cured, put back original part and change next item - test .... keep doing this till cure is found.
But whatever - for newcomers to the hobby - it means costs. For oldies like me - we have spare gear on bench ....

Nigel

My spare parts box is growing in leaps and bounds :D

"I must tend to agree with another about changing too many things" - Exactly - I did not expect the plane would fly any different or that the flutter would magically disappear. It made sense to me to go ahead and give it a test flight though... really just to make sure all the parts I just replaced worked.

The lemon is on it's way... going to change it out and fly again.

.... and go from there.

If that fixes it, then hallelujah! :D

If not... land it, and .... no clue ????

woodmangler 06-08-2015 03:59 PM


Originally Posted by xmech2k (Post 975919)
IIRC, we brought up the rx long ago. He didn't replace it. We're along for the ride!

System over load my friend... (system = my widdle bwain)

Going to replace the receiver tonight (if it gets delivered as promised)

.... and onward from there :)

woodmangler 06-08-2015 05:11 PM


Originally Posted by birdDog (Post 975885)
Heck, if nothing else, even one of these $1.50 gadgets. Rigging up a stand with two leveled razor blades makes it work even better.

http://cdn.hobbyking.com/hobbyking/s...ncer-14927.jpg
http://hobbyking.com/hobbyking/store..._Balancer.html

I know people who brag about never having balanced an e-prop. If they only knew.

Now I know. Ordered it - on it's way. Thanks!

xmech2k 06-08-2015 06:05 PM


Originally Posted by solentlife (Post 975922)
Just a comment about out of balance props and effects.

I have trouble thinking an unbalanced prop would cause flutter ... take my glow powered jobs ... when engines running and all is balanced - the model is still vibrating ... surfaces vibrating on the ground.
Surely you would need a serious difference on the prop balance to cause flight flutter ? Especially that E props are lighter and less liable to vibration etc.
I did have a prop cause me trouble on one E model ... part of a blade got clipped on take-off and I cont'd to fly .... yeh I know Silly ! When I landed - the motor mount and firewall was separating from the fuselage but flight was fine.....

Nigel

The balance wouldn't directly cause the flutter, it could cause the AS3X to freak out and shake one or more control surfaces really fast. AS3X flutter rather than aerodynamic or whatever the term isfor 'normal' flutter.

solentlife 06-08-2015 07:12 PM


Originally Posted by xmech2k (Post 975931)
The balance wouldn't directly cause the flutter, it could cause the AS3X to freak out and shake one or more control surfaces really fast. AS3X flutter rather than aerodynamic or whatever the term isfor 'normal' flutter.

Just trying to fathom out why the 'gyro' would flutter if the surface is not. I use 3 axis stab's on Fuel and E powered. The 3axis stab is silent regardless of vibration from Fuel motor vibration until model is tipped or moved from reference attitude.
The only way I could see it being affected by vibration or prop balance is if the mounting of the AS3X is loose and allows the gyros to move about - interpreting this as model movement.

I do agree that once gyro starts correcting and if gain is too high - it gets into 'oscillation' that can speed up significantly as it fails to correct the problem. But turning down gain is universal answer for that.

Not trying to be difficult - just trying to see it as a problem from a prop.

Nigel

solentlife 06-08-2015 07:44 PM


Originally Posted by woodmangler (Post 975930)
Now I know. Ordered it - on it's way. Thanks!

Now al you need is two domestic shelf 90 degree brackets screwed to a block of wood. The shaft then sits on the bracket edges. No need for knife blades or glass etc. the round shaft gives only a tiny contact point anyway.

If you want to get smart and have an old burnt out motor ... you take two magnets from the motor bell. Glue them to the wood or CF side pieces such that the shaft of your balancer sits nicely between and held by the magnets. Perfect friction less hanger !

http://i6.photobucket.com/albums/y24...psqiq9f9t9.jpg

http://i6.photobucket.com/albums/y24...psgzndeqep.jpg

Nigel

theapplepi3.14 06-08-2015 08:58 PM

I agree balancing the prop is good practice, but that is not what he wants advice on. He wants you to help him save a sinking boat, and instead of patching the hole you are tightening rivets - to speak metaphorically.

Get an Rx WM!

woodmangler 06-08-2015 09:59 PM


Originally Posted by theapplepi3.14 (Post 975942)
I agree balancing the prop is good practice, but that is not what he wants advice on. He wants you to help him save a sinking boat, and instead of patching the hole you are tightening rivets - to speak metaphorically.

Get an Rx WM!

Ordered.. supposed to here today

theapplepi3.14 06-08-2015 10:58 PM


Originally Posted by woodmangler (Post 975947)
Ordered.. supposed to here today

Awesome! I hope it fixes the problem! It will also help us get the other Rx working;)


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