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Old Mar 14, 2011, 09:16 PM
Blade mSR freak
hydro_pyro's Avatar
Irish Hills - SE Michigan
Joined Jan 2010
2,054 Posts
I made an important discovery today...

Some pilots have reported having trouble with touchy pitch/throttle, and tail blowouts under fast punches. The manual recommends 70% travel for the pitch channel.

However, I made the mistake of setting up this travel only with the stick in the down position, which of course only changes the travel below middle stick, since the DX6i allows you to set up and down travel separately. The stick needs to be moved above center to set the "up" travel value, which was accidentally left at 100% the first time.

If the pitch travel foth BOTH up AND down are set to 70% as recommended, the tail will NOT blow out.

With up AND down pitch BOTH set to 70%, it's MUCH easier to control altitude, and the tail does NOT blow out under full positive pitch.
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Old Mar 14, 2011, 09:22 PM
Tail-in hover expert ;)
mediclavina's Avatar
United States, LA, Shreveport
Joined Aug 2006
936 Posts
I had the pitch travel on mine set at -55% to +66%. This gives 10 degrees for both positive and negative maximum pitch travel. The lower percentage value on the negative pitch side is due to the fact that the servos on my mCP-x has longer negative throws than positive.
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Old Mar 14, 2011, 09:23 PM
certified crash instructor
Scottsdale Arizona
Joined Dec 2009
2,214 Posts
Hydro, thanks for the info, just tried it and it worked!
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Old Mar 14, 2011, 09:27 PM
If it ain't broke, fix it.
Hasher66's Avatar
USA, OR, Portland
Joined Jan 2004
1,187 Posts
Quote:
Originally Posted by Rif View Post
will these settings work with the dx8?
I wouldn't see why not. I've reset them back to DR/EXP = 70%/30% for NORM, since I prefer that more than the 65%/35%.

Status report: 15 batteries thru the mCPx now.

Was a hair twitchy around hover, so rechecked zero pitch at 50% stick and adjusted up two turns on each servo link. Also jacked up the headspeed a small amount and softened the pitch curve just a little and she's now dialed in as far as I can tell.

Checked grips and they are still nice and tight. Pulled off grips anyway and checked bearings. Looked good, put grips back on and still nice and tight, no slop.

Damage so far, (14 batteries inside, 1 battery outside): One popped head link, snapped back on. 5 or 6 times main gear popped down, pushed back up. End of blade tips a bit scuffed, (couch), and green, (Ficus), with one small ding, (table leg).

So far, TH has been my buddy...so for all of you CP noobs out there, make friends with it as soon as you can.

Ta ta for now.
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Old Mar 14, 2011, 09:29 PM
Blade mSR freak
hydro_pyro's Avatar
Irish Hills - SE Michigan
Joined Jan 2010
2,054 Posts
Also... (hopefully this has been well-covered already)...


Many of these birds are being shipped with less than neutral pitch at mid-stick, which will give you an imbalance of up and down pitch, resulting in the point of lift-off being noticeably far above mid-stick. It's important to verify the main gear is fully seated with NO up/down play in the main shaft before adjusting. If you activate throttle hold with a linear pitch curve, and flop the blades to one side, you can easily see where "neutral" pitch is, because the blades will line up perfectly with each other. If perfect mid-stick does not give you neutral pitch, you can unsnap/adjust/re-snap all three servo link heads equally until you have neutral pitch at middle stick. The heads must be adjusted one full turn at a time so they don't get forced on backwards. Most of them seem to need the link heads un-screwed one to four turns before things are in balance.

Hope this helps...
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Old Mar 14, 2011, 09:48 PM
Registered User
Joined Jul 2007
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Quote:
If perfect mid-stick does not give you neutral pitch, you can unsnap/adjust/re-snap all three servo link heads equally until you have neutral pitch at middle stick. The heads must be adjusted one full turn at a time so they don't get forced on backwards. Most of them seem to need the link heads un-screwed one to four turns before things are in balance.
I have seen many folks talk about this issue, and I had this problem. I simply adjusted my pitch sub-trim. Voila. Problem solved.

I'm using a JR8103 with the Spektrum-RF module though. (thank you Spektrum!)

Is there anything different setting the pitch subtrim with the DX series transmitters? Or are we talking the stock transmitter, which may not have subtrims?
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Old Mar 14, 2011, 09:54 PM
Heli Mad
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Australia, VIC, Elsternwick
Joined Feb 2002
972 Posts
Hi clintfisher
I am about to set up one of these with a JR radio and was wondering if you would mind sharing your settings?

Cheers
Stephen
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Old Mar 14, 2011, 10:09 PM
DJI Support
Las Vegas/Lake Tahoe
Joined Feb 2010
9,245 Posts
Quote:
Originally Posted by clintfisher View Post
I have seen many folks talk about this issue, and I had this problem. I simply adjusted my pitch sub-trim. Voila. Problem solved.

I'm using a JR8103 with the Spektrum-RF module though. (thank you Spektrum!)

Is there anything different setting the pitch subtrim with the DX series transmitters? Or are we talking the stock transmitter, which may not have subtrims?
There is no substitute for a good mechanical setup. I have built three FBL helis and you want your subtrims as close to zero as possible. If you set up the heads correctly, the bird will fly perfectly from the beginning.
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Old Mar 14, 2011, 10:16 PM
VAPORIZED
pappy1's Avatar
Australia, SA, Adelaide
Joined May 2010
1,267 Posts
Quote:
Originally Posted by hydro_pyro View Post
I made an important discovery today...

Some pilots have reported having trouble with touchy pitch/throttle, and tail blowouts under fast punches. The manual recommends 70% travel for the pitch channel.

However, I made the mistake of setting up this travel only with the stick in the down position, which of course only changes the travel below middle stick, since the DX6i allows you to set up and down travel separately. The stick needs to be moved above center to set the "up" travel value, which was accidentally left at 100% the first time.

If the pitch travel foth BOTH up AND down are set to 70% as recommended, the tail will NOT blow out.

With up AND down pitch BOTH set to 70%, it's MUCH easier to control altitude, and the tail does NOT blow out under full positive pitch.
Doesnt the manual state%75?
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Old Mar 14, 2011, 10:19 PM
certified crash instructor
Scottsdale Arizona
Joined Dec 2009
2,214 Posts
Quote:
Originally Posted by pappy1 View Post
Doesnt the manual state%75?
Yeah but it doesn't say you need to move the throttle stick past 50% to change the positive pitch. Go to the travel adjust menu, click on the pitch, move the throttle stick past 50% and the pitch changes to 100%, you need to adjust this to 70-75%.
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Old Mar 14, 2011, 10:21 PM
Pro beginner
rchelijc's Avatar
Melbourne, Australia
Joined Aug 2010
752 Posts
Quote:
Originally Posted by mediclavina View Post
I had the pitch travel on mine set at -55% to +66%. This gives 10 degrees for both positive and negative maximum pitch travel. The lower percentage value on the negative pitch side is due to the fact that the servos on my mCP-x has longer negative throws than positive.
Med, although not absolutely critical, have you tried setting up perfect 0deg pitch at 50% stick pos?

I found that doing this saves me the pain of doing mental calculations later on when playing around with pitch curves. I posted earlier back with pics on how to do it accurately.

Note: if you do it that way, instead of having the blades in a straight line like I did, fold them so that they are close to parallel. It's mechanically more accurate, since the weight of the blades tends to drop the blade grips a bit. So if in a straight line, perfect swash setup should like the blades are slightly drooping (They should droop as much if the heli is inverted)
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Old Mar 14, 2011, 10:22 PM
VAPORIZED
pappy1's Avatar
Australia, SA, Adelaide
Joined May 2010
1,267 Posts
Quote:
Originally Posted by slo-fly View Post
Yeah but it doesn't say you need to move the throttle stick past 50% to change the positive pitch. Go to the travel adjust menu, click on the pitch, move the throttle stick past 50% and the pitch changes to 100%, you need to adjust this to 70-75%.
just about to uploAD A PHOTO OF DX6I SCREEN
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Old Mar 14, 2011, 10:27 PM
Pro beginner
rchelijc's Avatar
Melbourne, Australia
Joined Aug 2010
752 Posts
Quote:
Originally Posted by hydro_pyro View Post
Also... (hopefully this has been well-covered already)...


Many of these birds are being shipped with less than neutral pitch at mid-stick, which will give you an imbalance of up and down pitch, resulting in the point of lift-off being noticeably far above mid-stick. It's important to verify the main gear is fully seated with NO up/down play in the main shaft before adjusting. If you activate throttle hold with a linear pitch curve, and flop the blades to one side, you can easily see where "neutral" pitch is, because the blades will line up perfectly with each other. If perfect mid-stick does not give you neutral pitch, you can unsnap/adjust/re-snap all three servo link heads equally until you have neutral pitch at middle stick. The heads must be adjusted one full turn at a time so they don't get forced on backwards. Most of them seem to need the link heads un-screwed one to four turns before things are in balance.

Hope this helps...
Hydro, posted in pg 1 of this thread here.

But follow dbennettya's tip here of having them in parallel instead of in a straight line.

Reason: there is play in the swash. The weight of the blade at this angle will make it droop down slightly. By them being in parallel, you'll find that if they both droop the same, and are aligned to one another, then you've got perfect 0deg pitch. A good check is grab the heli and invert it - they should droop the other way, and yet still be aligned.
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Last edited by rchelijc; Mar 14, 2011 at 10:29 PM. Reason: spelling
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Old Mar 14, 2011, 10:51 PM
Registered User
Joined Jul 2007
34 Posts
Quote:
I am about to set up one of these with a JR radio and was wondering if you would mind sharing your settings?
I'm not a CP Heli expert, so I'm figuring this out as I go. The stock settings on the DX7 and DX8 were a good start. (which JR do you have?)

The DX7 most closely resembled my available settings. Left the gyro stuff at INHibit.

As for the throttle-pitch curves. Well, I'm not a 3D flyer yet, so I'm focusing on NORM mode, where I start getting used to proper landings, using throttle-hold (not in the greatest reach for me), and building cyclic-orientation skills.

With livingroom-spot-landings in mind, and only 2D flight, I went with a NORM pitch curve of 49 50.5 54.5 75 100, which limits my accidental down-slam risks and makes take-offs from perches easier.

My NORM throttle curve is 0 50 67 86 100.

I don't have negative throttle curve % values on this radio, otherwise, the first number would be -10% or so, to make sure that it would get below any accidentally set trim offset.

Happy flying and get used to throttle hold. I wish there was a way to keep the tail from spinning on TH though.
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Old Mar 14, 2011, 10:54 PM
Tail-in hover expert ;)
mediclavina's Avatar
United States, LA, Shreveport
Joined Aug 2006
936 Posts
Quote:
Originally Posted by rchelijc View Post
Med, although not absolutely critical, have you tried setting up perfect 0deg pitch at 50% stick pos?

I found that doing this saves me the pain of doing mental calculations later on when playing around with pitch curves. I posted earlier back with pics on how to do it accurately.

Note: if you do it that way, instead of having the blades in a straight line like I did, fold them so that they are close to parallel. It's mechanically more accurate, since the weight of the blades tends to drop the blade grips a bit. So if in a straight line, perfect swash setup should like the blades are slightly drooping (They should droop as much if the heli is inverted)
The first thing that I checked is the pitch angle at mid-stick (50% stick position). I also do the blade folding when checking/setting up zero degree pitch, so I'm very sure the blade pitch is at neutral at mid-stick position. I also had to tilt the heli sideways to get an accurate measurement when I noticed some play on the blade which causes them to sag. This is also how I discovered that my mCP-X head had more negative travel than positive.
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