First Hovers

[Dafics]

First hover today! Just lifted into a hover with no fuss.
The heli seemed very twitchy in cyclic so I reduced the throws via the Tx dual rates by 20% to make it more manageable.
The tail had a twitch side to side which wouldn't go away despite reducing the tail gain to 40% (really no difference at 65% gain).
Most vibes below 1.0 except around 210hz to around 2.0 with the same around 400 and 480Hz.
The self level at centre (80%) didn't seem to be very effective although I don't believe I gave it a fair trial. Will try active always next time.....
Vibe logo file attached for comments....
Thanks in advance
John
Trex500 with Scorpion 3026 1400kv, 15T pinion and headspeed at hover 2700rpm
(RPM sensor coming for governor)

[snowball75]

I did my first hover on my protos. I have a bad tail bearing so my response here may be a little skewed.

Your log looks similar to mine. I got a spike at around 210hz then it cleared itself. For me, it was a bearing that was wearing out. You may want to see if there is any play with the tail bearings.

[georgi UK]

=] good one!!

for the tail reduce the gov gain, mine is around 32 for a T5 but not at your headspeeds! get some expo on the cyclics, this will help smooth it out nicely. vibes are showing tail and motor but this thing is revving its nuts off! they are not bad by any means and may settle when the gov calms down using less gain, its mostly lateral ( sideways ) acceleration we are seeing here.



the SL will be least effective until the bell gains increase from defaults, it needs a few flights to see this increase. auto tune bell gains needs to be enabled in the software. you can increase this manually. if you wish.

[Dafics]

Probably won't have the opportunity to do more testing until later in the week or maybe the weekend so the RPM sensor should be in hand by then.

I will reduce the tail gain further as suggested and add expo via the TX (only have 10% at present).

I can't find the thread that descibed calculating the "gear ratio"...... Main gear 162, pinion 15 and 10 pole motor so ratio = (162/15)/10?

What headspeed would you recommend for normal and idle up bearing in mind I have only just started flying gentle circuits and want to progress ( in time) to basic aerobatics?
TIA
John

[taoY]

Gear ratio = (main gear / pinion) * magnet pole / 2
(162/15) * 10 /2 = 54

[Ken Here]

Originally Posted by gmcallister

=]

the SL will be least effective until the bell gains increase from defaults, it needs a few flights to see this increase. auto tune bell gains needs to be enabled in the software. you can increase this manually. if you wish.

To manually increase bell gains, Stock setting show 40/48 percent. How high can a person go to make it a lot more effective? Would 100/100 percent be Ok to try for non 3d, non inverted sport flying? Thanks.

[georgi UK]

Originally Posted by Ken Here

To manually increase bell gains, Stock setting show 40/48 percent. How high can a person go to make it a lot more effective? Would 100/100 percent be Ok to try for non 3d, non inverted sport flying? Thanks.

=] I ran 100 % at one stage in testing just to see these effects, I wouldn't recommend going this high, the heli felt very aggressive using the CS + as it switched in and out of SL

70/75% is a good manual value starting point using "self tune".or optimiser as V-bar term it. to get some idea of how to use it for aileron and elevator this is worth a look =

[ame]http://www.youtube.com/watch?v=3pkuEcrtFOI[/ame]

[Dafics]

I finally got time to try the setup again without wind and/or rain!
I have added an RPM sensor and set the HS at 2500RPM, also added expo via the TX to ELE and AIL (both 25%). This resulted in a much nicer machine.
2500RPM sounded a bit high so I dropped it to 2250RPM which was much nicer. I also manually increased the Bell gain to 55/62 for the SL. Also a good move and made for a stable heli.
Then the problems started.
With SL active the heli wanted to drift left (didn't initially) and then, I think, backwards as well.
I loaded another battery and had another flight which seemed to be going quite well with some gentle forward flight. Also the odd punch of the throttle to confirm I had plenty of overhead with the governor, plenty available!
I was at about 20 feet in slow forward flight and the motor stopped resulting in a firmish arrival with no apparent damage (2.0 vibe on landing). Moved it back onto the field and it spooled up normally. I low hovered for about 30 seconds before giving up for the day (70% left in the battery).
Throughout all the above I was trying to smooth a tail tick. The gain at about 32 seemed best, the tick was worse at 20% so back to 32%.....
Then at home the Data Viewer wouldn't work. The Playback was OK but couldn't get the Vibe Log to work despite upgrading to the Pro version. Each time I opened the Viewer I had to reinsert the code to get it to work.
Attached are the Vibe Log from the first flight and Playback Log from the third flight (when the motor stopped at around the 2:30 point).
Thanks in advance
John

[georgi UK]

=] John we need the logs please!!

[Dafics]

Logs attached. (it has been a long week).

[georgi UK]

=] John hi, its showing a gov sensor malfunction or connection failure maybe? the rpm's were holding well until around 155 secs in where the throttle was "handed back" as a conventional stick input.



the part that confuses me, it shows normal / idle 1 set at different values to what would be expected if the gov wizz had been used, this could well be me after a hard week??!

the accelerometers look fine, do a trim flight here to help with any drift in SL, this involves temporarily setting the hiller decay to 200% on a calm day, allowing linkage or software servo trims to be adjusted.

the tail servo ball needs to move to the innermost arm position as a side note!

its hard to say all this without it sounding picky, which I'm not being, so hope it reads back ok to you!

[Dafics]

Georgi,
Don't khow what happened at 155sec, just seemed to loose the motor. I added collective to reduce my rate of descent so I would have thought there would have been enough throttle to powerup?? After I walked the 25metres to the heli to move it out of the long grass it seemed to respond normally. Hovered at half a metre for 20-30 seconds as normal.
I need to alter the pitch curve as the first hover with gov had me on the cusp of the throttle curve at hover - it was up and down like a pogo stick as I went from too much to not enough thottle/pitch. The solution was to move the thottle curve cusp to a point of lower stick travel. I will redo the throttle curve as per wizard and adjust the pitch curve instead.
The tail servo is on the inner hole - I will fit a shorter arm to the servo.
Do you sound picky? Not at all! I want to get it right and your help is appreciated.
Regards
John
PS How were the vibes at the lower headspeed?

[georgi UK]

=] John yes, vibes not too bad. it looks like 5 samples were taken, this shot is typical for any one of them, bit of tail & motor showing imbalance?

[Dafics]

Motor pinion seemed to have a little too much run out so borrowed motor with much less runout now fitted and new bearings on order.
Data Viewer fixed by Skooum (fast response to email)
Additional TT bearing holders also on order....
Could the motor/ESC bullets being just a little loose (or not as tight as I would like) cause my motor stoppage?
TIA
John

[Dafics]

New motor (old one had excessive bearing wear and they fell apart when I tried to remove them), tail rotor checked ( a little slop taken out of the holders) and balance confirmed, additional TT bearings added.

40 odd seconds of hovering and all looked good..... then plop it went from about 4 feet to the ground in a split second (or so it seemed).

No damage so after collecting my thoughts I lifted to a one foot hover. after a gust of wind/ brain fade/ loss of concentration I managed to slide the tail into the ground followed by the main blades.

Just a bent boom....... (more details on the T500 board if you have comments/suggestions)

My concern is why it went from 4ft to ground without warning. Georgi suggested when it happened last time maybe the gov. Maybe ESC? (it runs a separate volt reg for the radio gear.) Maybe?????

(I did 4 or 5 short hover flights before FBL conversion and a couple of these had symptoms of low battery power -ESC reduced power. It was not consistant and happened with 50-70% battery left. Connected with this? Maybe?)

TIA
John
PS the vibes looked good

[georgi UK]

=] John hi, the vibes are looking great!

the throttle dips out of gov mode then re-establishes its connection, the gear ratio needs to be set at 37.38. for a stock T500



the voltage looks good throughout, how humid is it there? are the sat's blinking when this happens to suggest a static hit?

[Dafics]

Georgi,
Not a stock setup - Scorpion 3026 1400kv and 15T pinion, so 162/15*10/2=54

Radio and SK720 fed by CC 10amp reg so the voltage should be consistant ( as per plot).

The first event (seems like weeks ago) the air temp was around 13C and yesterday was around 18C. Both days were damp but not what I would call humid. Plus I don't have a belt, I have a TT setup (T500ESP). The first event was after 155secs and yesterday 42 secs so the conditions would have to be lots different if it was a static buildup. Yes?

I didn't have the presence of mind to look at the SK720 or the Sat Rx (either of them) but the log file indicates 8 and 9 frames lost from the Sats which doesn't sound like much...

Apart from a new boom, where do I go from here?
TIA
John

[georgi UK]

=] John, its beginning to look like an ESC issue? all other things add up. yes sorry missed the TT clue as to what tail drive you were using, have you a spare ESC or borrow one to try out? low hovering tests tho'

[Dafics]

Georgi,
I have organised a CC Lite ICE 75 to try. It should arrive in a few days as should the boom.
Bring on the low hovers without brain fade!!
Thanks
John

[Dafics]

Correction to previous post: CC Phoenix ICE 75