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Old Oct 21, 2012, 08:43 PM
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United States, CA, Modesto
Joined Aug 2012
828 Posts
Quote:
Originally Posted by Rollmops67 View Post
Today, I had a weird issue, I want to share it with you in case it happens on your helicopter.
While I was flying my EH200-modified F45 over a freshly harvested corn field, the rotor suddenly simply stopped to rotate and the heli fell from about 15 meters (45 feet) like a stone.
Not a very pleasant vision, believe me...
After the crash the heli seemed still to be bound with the transmitter, the white led was on.
Damaged parts :
- bent flybar, but okay it's not the first (neither the last) time, I bent it straight.
- slightly bent tail boom, I straightened it with no problems.
- a crack in the canopy beneath the skids (the F45 felt on the nose)
- biggest damage : a broken gyro on the RX board.

I tried to understand what happened.
The transmitter worked fine, batteries were charged.
I tried to bind to the helicopter to the TX, all was OK, the white led became steady as allways, even whith the broken gyro.
But each time I spooled up the heli, after a few seconds the main rotor stopped and the white led began to blink slowly.
The tail motor didn't run, I tought this was because the gyro was broken.
And each time I put the throttle to 0 on the Tx the white led became steady again, and I could spool up the rotor, which stopped again with blinking led, and so on...
First I thought the ESC had a problem (short-circuit ?).
Then while playing with the RX board, I noticed that each time I tried to spool up, a surface mounted electronic component next to the tail motor connector became hot.
Aha.
I disconnected the tail motor to see what happens, and now the helicopter spooled up whithout problem and the main rotor worked normally.
So the culprit was the tail motor wich had a short.
I think the RX board has a protection circuit wich detects an overcurrent in the motor and the "switches off" with the white led blinking.
The motor had just about 30 flights
I replaced the RX board, the tail motor, and now it flies again.

Roland
I wrote about the same issue earlier. The flybar hits the canopy right on the gyro. This is what broke off your gyro and more than likely did more damage to your board.
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Old Oct 21, 2012, 10:56 PM
Fly Fast, Fly Hard, Fly Fun
rexless's Avatar
Canada, BC
Joined Apr 2012
1,475 Posts
Quote:
Originally Posted by OldOz View Post
Interesting that others find problems with 'bouncing' in flight. I thought that this was just due to some of my more extreme mods, but still was hesitant to personally recommend the F45 to Solarcow for FPV because of this. For anything else, the F45 is tops. But in view of previous experience with the F39 (very stable as a camera platform in very LIGHT winds) and now the Trex 450 (sits like a rock in attitude, though trying to dash off without constant attention like all flybar CP) - just don't know. I guess BThirsk may have hit the nail on the head. Alas, no real solution suggests itself.
Rexless - Get better soon!
I have a lot of hills and valleys right where I fly and just the other day I noticed that anytime I tried to approach my house I had a heck of a time descending through the rising air currents. If I went slowly I ended up bobbing and gaining altitude. Quickly wasn't a great option if I wanted to avoid smashing into my house. If I hold the helicopter at the spot where the blades are mounted and rock it back and forth, and compare that to what the heli looks like when it's rocking 100m in the air - it looks very much the same. If I hold the flybar and rock it again it seems very much the same. So what I'm trying to understand with that is why is it the flybar flapping and not the blades? I see why it would seem unlikely to be the blades but I can also see how it might be the blades switching positions while the flybar holds steady. I don't really know enough about it obviously

Quote:
Originally Posted by BThirsk View Post
Notice on several of these photos that the blade holder is not 90 degrees to the main shaft. It has to be and cannot change if the metal pivot rod is installed in the blade holder through the main shaft. If you hold the blades straight out, can you lightly wobble the blades up and down causing the blade holder to move on the main shaft? If so, the pivot pin is missing.
Nicely done!

Thanks OldOz for the get well. I am finally that again. I was barely out of bed when I modified the new blades to fit the F45. Once I had a real meal I went out and gave it a test flight with the 2s battery and it was very smooth but noticeably under-powered. If I had any downward speed it took quite a bit to recover. So I went ahead and mounted the 3s+2s combo and disaster struck. I seem to be doing something wrong as I ended up with a serious crash, busted blades, cracked canopy and a broken skid support. It was quite bad actually as I crashed into the neighbours house. Fortunately it hit their roof and bounced off instead of hitting the window. No damage to the house! With the 3s+2s I must have the balance all messed up as I felt like it was hard to maneuver. I'm going to try moving the battery position around and setup my backup pair of HB blades and give it another try.
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Old Oct 21, 2012, 11:54 PM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
Glad to see you're up and about again, Rexless....
No so good about your heli. But all in the cause of the 'ultimate' F45!
Regards
- John.
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Old Oct 22, 2012, 12:01 AM
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Joined Oct 2012
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Quote:
Originally Posted by mumilove View Post

When ever i want it to move against the wind, i'll keep giving a little throttle and let of again.. like when you spin the engine in your car.. this way it will not go higher and you will give the bird momentum...
Instead of using the throttle, you can also try giving short 'jabs' (meaning forward cyclic for a few seconds, ease off, forward cyclic, ease off) of forward cyclic to build up a forward impulse, followed by slight forward cyclic continuously. The effect of wind seems to increase rapidly at any height above 10 feet, and closer to the ground forward cyclic seems to work better, but you need to be careful you don't nosedive into the ground.
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Old Oct 22, 2012, 12:18 AM
John
Australia, QLD, Brisbane
Joined Aug 2012
542 Posts
The 30g of putty in the front of the canopy, heavy Turnigy battery (and a few other mods) also work wonders for wind authority - well, for me, anyway. No uncontrolled nosedives yet, but watching for them!
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Old Oct 22, 2012, 01:05 AM
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Joined Oct 2012
802 Posts
Shims giving F45 sluggish 'rough' flight characteristics

I made shims out of the plastic collar support from a new shirt, and adjusted the blade holder screws till the blades were able to swing with some resistance but still quite freely. The up-down play before shimming was no longer present. I find the helicopter has become sluggish and 'rough handling'. Is this something to be expected?

PS Also had a crash after nearly three weeks, hitting a metal fence (heard the 'twang' from where I was standing a great distance away!) It was at a low altitude and I basically cut the power when I realized it was getting away beyond the fence. It fell through the grass and onto the rocks below the fence, but not even a scratch that I can see!

Lesson: Never fly when you have a limited space to make corrections if a sudden gust of wind blows. I was flying away from my usual location at the corner of a field, since some guys with 5 Alsatians were out there trying to teach them tricks, and I decided to keep a healthy distance from them with my F645
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Old Oct 22, 2012, 03:07 AM
Hangin' for a strong SW
slothy89's Avatar
Australia, VIC, Sebastopol
Joined Apr 2012
765 Posts
Quote:
Originally Posted by Lentar View Post
I made shims out of the plastic collar support from a new shirt, and adjusted the blade holder screws till the blades were able to swing with some resistance but still quite freely. The up-down play before shimming was no longer present. I find the helicopter has become sluggish and 'rough handling'. Is this something to be expected?
Sounds like your shims may still be too tight.. You don't want to have to loosen the screws just to allow for movement, you are better to get thinner shims. There is a good chance that by loosening the screws you have created a new issue.

Try finding a thinner source of plastic to shim with. Or try sanding the current shims a bit thinner.

The blades should still fall under their own weight (when heli is held sideways) but only just. If they are any stiffer, they may not fully straighten out when you apply throttle causing imbalances in the rotors.
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Old Oct 22, 2012, 03:22 AM
Eternal beginner
Rollmops67's Avatar
France, Alsace, Strasbourg
Joined Jun 2012
640 Posts
Quote:
Originally Posted by arrowshooter View Post
I wrote about the same issue earlier. The flybar hits the canopy right on the gyro. This is what broke off your gyro and more than likely did more damage to your board.
In my case it was not the flybar wich hit the gyro.
As I said the rotor stopped while flying, so the flybar wasn't turning when the heli hit the groud.
But it fell directly on the nose and the canopy absorbed a part of the energy and moved back about half an inch (thus the cracked canopy near the landing skids).
In my case there is no doubt it is the moving back canopy wich bent the gyro.
Even the servo and throttle connectors were bent backwards !

Roland
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Old Oct 22, 2012, 03:45 AM
Hangin' for a strong SW
slothy89's Avatar
Australia, VIC, Sebastopol
Joined Apr 2012
765 Posts
Quote:
Originally Posted by Rollmops67 View Post
In my case it was not the flybar wich hit the gyro.
As I said the rotor stopped while flying, so the flybar wasn't turning when the heli hit the groud.
But it fell directly on the nose and the canopy absorbed a part of the energy and moved back about half an inch (thus the cracked canopy near the landing skids).
In my case there is no doubt it is the moving back canopy wich bent the gyro.
Even the servo and throttle connectors were bent backwards !

Roland
Sounds like it landed upside down, nose first! That would've been a painful looking landing.
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Old Oct 22, 2012, 05:05 AM
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Joined Oct 2012
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Quote:
Originally Posted by slothy89 View Post
Sounds like your shims may still be too tight.. You don't want to have to loosen the screws just to allow for movement
Very interesting possibility! Wish I had access to a micrometer to check the shim thickness.

I want to clarify that the screws I had to loosen are the single screws through which the hole at the end of the blade passes, not the two screws at the base of the blade holder assembly.

I can use thinner plastic or even a soda can like someone else did for the shims, and see if that makes a difference.
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Old Oct 22, 2012, 05:41 AM
Brent 黑雁
BThirsk's Avatar
Canada, AB, Ponoka
Joined Jan 2012
1,756 Posts
Quote:
Originally Posted by Lentar View Post
Very interesting possibility! Wish I had access to a micrometer to check the shim thickness.

I want to clarify that the screws I had to loosen are the single screws through which the hole at the end of the blade passes, not the two screws at the base of the blade holder assembly.

I can use thinner plastic or even a soda can like someone else did for the shims, and see if that makes a difference.
As Slothy89 said, you need thinner shims. When you tighter the screw, it needs to reasonably tight so the two halves of the blade holder are in contact. That keeps the screws from backing out and also helps keeps the blade holder ridged.
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Old Oct 22, 2012, 05:45 AM
Brent 黑雁
BThirsk's Avatar
Canada, AB, Ponoka
Joined Jan 2012
1,756 Posts
Quote:
Originally Posted by rexless View Post
I have a lot of hills and valleys right where I fly and just the other day I noticed that anytime I tried to approach my house I had a heck of a time descending through the rising air currents. If I went slowly I ended up bobbing and gaining altitude. Quickly wasn't a great option if I wanted to avoid smashing into my house. If I hold the helicopter at the spot where the blades are mounted and rock it back and forth, and compare that to what the heli looks like when it's rocking 100m in the air - it looks very much the same. If I hold the flybar and rock it again it seems very much the same. So what I'm trying to understand with that is why is it the flybar flapping and not the blades? I see why it would seem unlikely to be the blades but I can also see how it might be the blades switching positions while the flybar holds steady. I don't really know enough about it obviously


Nicely done!

Thanks OldOz for the get well. I am finally that again. I was barely out of bed when I modified the new blades to fit the F45. Once I had a real meal I went out and gave it a test flight with the 2s battery and it was very smooth but noticeably under-powered. If I had any downward speed it took quite a bit to recover. So I went ahead and mounted the 3s+2s combo and disaster struck. I seem to be doing something wrong as I ended up with a serious crash, busted blades, cracked canopy and a broken skid support. It was quite bad actually as I crashed into the neighbours house. Fortunately it hit their roof and bounced off instead of hitting the window. No damage to the house! With the 3s+2s I must have the balance all messed up as I felt like it was hard to maneuver. I'm going to try moving the battery position around and setup my backup pair of HB blades and give it another try.
I thing the bobbing is the flybar swinging back and forth over center(90% to the main shaft) trying to stabilize that is causing the bobbing. I think low head speed and the correct updrafts and rotor wash all combine to creat this effect.

What type of issues did you have before your crash?
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Old Oct 22, 2012, 06:14 AM
Eternal beginner
Rollmops67's Avatar
France, Alsace, Strasbourg
Joined Jun 2012
640 Posts
Bobbing, wobbling

Quote:
Originally Posted by BThirsk View Post
I thing the bobbing is the flybar swinging back and forth over center(90% to the main shaft) trying to stabilize that is causing the bobbing. I think low head speed and the correct updrafts and rotor wash all combine to creat this effect.
After flying 2 F45's for about 4 months i think what is also causing the bobbing is the play in the different links, rods, connexions, swashplate, etc...
It's all plastic, and I can see with the naked eyes that I have play (among other places) between the links coming from AILE and ELEV servos and the balls on the swash plate.
There is also play on the swashplate itself between the rotating and the non-rotating part.
And the servos are also not of very big quality, there is noticeable play when you move the arms.
I remember, after a crash, one of my F45's was very prone to bobbing, what it never did do before.
I found out that it was the elevator servo wich had about 2 to 3 degrees of play when moving the arm.
I replaced the servo, and gone was the bobbing.
Actually, with the EH200 motor I have bobbing when I open throttle a little too much.
I believe here we are simply at the mechanical limits of the F45.
It's like if you take a car with a 80 HP motor and you put a 250 HP motor in it, the handling will become bad, because the chassis and the shock absorbers are not sized to transmit the 250 HP to the road.

Just my 2 cents (euro-cents, of course )

Roland
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Old Oct 22, 2012, 06:53 AM
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United States, FL, Hernando
Joined Sep 2012
1,460 Posts
I'll start by saying this (F45) is by far my favorte heli to fly with a high fun factor, but it is what it is , and the bang for the buck in stock form cant be beat. However much fun all these mods are, it makes more sense to move up a few grades to something of higher quality.

I'm a 40+ year professional mechanic/machinist/drag racer / bike builder and have built some crazy wheels in my time, once put a big block Ford engine into a Mercedes , but I think of the F45 as a Miata that just will never perform like a Ferrari, althought the Miata can be loads of fun.

Just my .02 devalued US cents worth
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Last edited by War Horse; Oct 22, 2012 at 10:30 AM. Reason: fat fingers
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Old Oct 22, 2012, 07:14 AM
Hangin' for a strong SW
slothy89's Avatar
Australia, VIC, Sebastopol
Joined Apr 2012
765 Posts
Quote:
Originally Posted by War Horse View Post
I'll start by saying this (F45) is by far my favorte heli to fly with a high fun factor, but it is what it is , and the bang for the buck in stock form cant be beat. However much fun all these mods are, it makes more sense to move up a few grades to something of higher quality.

I'm a 40+ year professional mechanic/machinist/drag racer / bike builder and have built some crazy wheels in my time, once put a big block Ford engine into a Mercedes , but I think of the F45 as a Miata that just will never perform like a Ferraril, althought the Miata can be loads of fun.

Just my .02 devalued US cents worth
Agreed, however there are people who just have to tinker for the sake of tinkering and IMO the F45 is a very suitable platform to do this. Even If the changes are largely over the top
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