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10-16-2017 10:49 PM  25 months ago
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3dorbust

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Hudson Florida usa

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Boom strike
I have had 3 boom strikes in one year of flight. What should I do to avoid them? I now have a dfc head and it came with a short main shaft. With all the upgrades I did my 450 is agile. I can only use vary small stick input. It feels like a much different helicopter. I no longer have a margin of error. But I like the performance.
I know how Icarus felt
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10-16-2017 10:53 PM  25 months ago
EEngineer

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TX

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Stiffer blade damping....or shorter blades...depending.Logo 600SXs, 800XX, TDR IIs
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10-16-2017 11:31 PM  25 months ago
JuanRodriguez

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The Villages, Florida

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What are you doing when having the boom strikes?? Landing? Autos ??

One thing that might help in your situation is to spool up the heli to takeoff RPM, then reduce speed and stop the blades WITHOUT moving the blades in their blade grips..... then carefully tighten the blade bolts to “lock” them in place as opposed to leaving them on the loose side . I do that with my Trex 600 and other helis I’ve owned.

Locked blades like that will help to minimize the boom strikes which occurs when the blades fold back and hit the boom.....
Been there, done that and old enough to know better.....
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10-16-2017 11:32 PM  25 months ago
AirWolfRC

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42½ N, 83½ W

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Are you talking about a blade strike in a hard landing or in hard 3D ?

What EE said . . . but more important . . . higher head speed.
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10-17-2017 01:39 AM  25 months ago
utahbob

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St. George Utah

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what's your pitch curve?
Regardless of your curves..memorize your collective stick position at which your heli lifts off the ground and don't drop the stick below that point when landing until your heli is on the ground and your headspeed is slower.
I do a great decending funnel!
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10-17-2017 02:09 AM  25 months ago
pctomlin

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Texas

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Blades could be to loose in the grips also. Need a good explanation of flight condition just prior to the boom strike to really give a good opinion on the cause. The low DFC head does play into the issue though.
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10-17-2017 10:12 AM  25 months ago
3dorbust

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Hudson Florida usa

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Boom strike
The first one I had was with a blade msr heli and my fault for sure. But two with my 450 one was major. The latest was minor but put a dent in the boom and chipped a blade. I was rolling right and trying to come out level. I input some rear then bit forward and it hit. When I was rolling right. I checked for problems before this by doing quick moves when hovering at the start. I will check my pitch curves and repost thanks.
I know how Icarus felt
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10-17-2017 11:46 AM  25 months ago
MartyH

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USA

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Since you managed to do that in flight, I'd suggest checking the dampers. Probably need to go harder. Also, make sure the thrust bearings were assembled properly.
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10-17-2017 04:19 PM  25 months ago
EEngineer

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TX

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With regards to the damper stiffness.....if the dampers are too stiff, you might experience vibration "resonances" as you are spooling up.

So one can use that as the upper range of damper stiffness.
Logo 600SXs, 800XX, TDR IIs
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10-17-2017 08:13 PM  25 months ago
AirWolfRC

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42½ N, 83½ W

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No comment on head speed ?
Realize that centrifugal force will reduce the coning angle and help keep the blades in a plane perpendicular to the main shaft.
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10-17-2017 08:55 PM  25 months ago
Flyin for Jesus

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Troy, IL. 62294

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If the boom strike happens when inverted, It would have to be caused by coning as airwilf said.
If caused during positive pitch, you could have blade lag where more pitch is worse not better.
Higher HS helps and also tighter blade grip bolts. However, my advise doesn't cover any mechanical problems.
Also, what does the swash plate look like that you have? the older ones used to pop off links if the dampers were too loose. Just putting that out there, I don't that much about the Walkera 450.
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10-17-2017 10:35 PM  25 months ago
3dorbust

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Hudson Florida usa

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Boom strike
Thanks guys. The thing is my walkera is somewhat of a trex clone as most parts fit. And the only thing original now is the frame. I just replaced the motor with a more powerful align 450. Believe it or not I went with a 60 amp hw ESC to run it cooler. I had a problem with a 50 amp? But now it's good. I had brought my head speed down and put in a bit more pitch to make it run cooler. I did not reset them with the new ESC and motor. I did just that today and it seem good. I'm not sure if it will happen again all I did was circuits and a climb out. How do I check the dampners? F shaft and Bering's are good.
I know how Icarus felt
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10-17-2017 11:21 PM  25 months ago
EEngineer

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TX

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Are your dampeners old?

If so, replace them.....See if they have some that are stiffer.
Logo 600SXs, 800XX, TDR IIs
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10-17-2017 11:33 PM  25 months ago
Pistol Pete

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Seffner, FL

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How do I check the dampners?
Best way is to compare to a new set.

If none available, just check and verify they are not cracked or broken and especially "spongy".

A quick means to also verify without removing is to make sure feathering shaft does not make contact with hub. You can pretty much tell how much "give" there is by observing how much grip moves up and down in reference to hub.
~~Enjoying the hobby one flight at a time~~
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10-18-2017 12:09 AM  25 months ago
3dorbust

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Hudson Florida usa

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Boom strike
OK I'm going replace them with new ones. And the new blades I put on are good carbon fiber. They are lighter and stiffer. I'm wondering if the dfc head has put the blades too close to the boom? It is closer now and of course no washout ams. It sure fly's good. The distance between the blades and boom is now 2 1\2 two and one half inches Is that OK it look like plenty of room?
I know how Icarus felt
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10-18-2017 01:08 AM  25 months ago
Flyin for Jesus

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Troy, IL. 62294

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2 1/2" should be plenty.
If its flexing that much, its the dampers, the blade grip tightness or too low HS.
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