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250 Oxy 3 Build

Discussion in 'Helicopters' started by murankar, Feb 28, 2019.

< Scale 500d/450 Size.. | Flight School >
  1. xokia

    xokia Active Member

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  2. murankar

    murankar Moderator Staff Member Armed Forces

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    Now this is for my Tattu packs

    Width 34.75mm
    Length 73.4mm
    Thickness 27mm

    These are my measurements not What is advertised.


    My guess is that i may have just added another minute of flight time with my changes. I won't know till the parts get here and I fixer up. I may go to 13 or 14 degrees of pitch. I am at 12.5 right now.
     
    Last edited: Mar 20, 2019
  3. xokia

    xokia Active Member

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    Thanks. I'm running 14 degrees I like the higher head speed. I need larger batteries I only get 3:30min of flight time.
     
  4. murankar

    murankar Moderator Staff Member Armed Forces

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    Got in 4 flights that were based on tuning. I just humbled myself today. Yeah I thought I knew how to tune but I guess not.

    At first in had a really bad nose left tap kick, 90° bad. So for what ever reason i thought speeding up the tail response was the ticket. Nope needed to go into advanced tail tuning. There I maxed out TC Coll setting. If this is what I think it is Then its a pre comp on collective. I got most of it out . Next I messed with the head gains, governor gains and tail gains. I thought at first I had to dial everything down since its a 250 and not a 450. I didn't quite get through it but I still have a ways to go.

    Punch outs are.drifting left, I think my tail stop gains are to high, head gain not high enough and I am not sure how to or when to dial in the governor. Right now I have it set low in VBar. I don't want it beating up the tail as I tune the tail. I have the gov down around 40 and it seems to be holding fine from what I can tell.

    I did good off on my last pack. Just getting comfortable with the oxy. I am getting somewhat better as the tune walks in.

    Tomorrow If its nice out i will video a flight.
     
    Last edited: Mar 20, 2019
  5. Tony

    Tony Administrator Staff Member

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    Can't wait.
     
  6. murankar

    murankar Moderator Staff Member Armed Forces

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    Both should be up today. Batteries get here today.
     
  7. xokia

    xokia Active Member

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    Had similar issues with the tail. I am using a spirit FBL . Gyro gain I have around 53. I did need to adjust the servo arm so the mechanical end points was around 150. Moved the ball further towards the servo.

    I like hard stops so mine is set kinda high. I did have to set some precomp but not much. Mine is pretty good now but still needs some fine tuning. What tail servo are you using? I’m using a KST 215
     
  8. murankar

    murankar Moderator Staff Member Armed Forces

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    I am running BK 3000 series servos all around. The tail is the 3005. Its comparable to yours.

    I may need to move the ball link like you did. I will also look and see what measurement I need to be at for That. I have the default location of second whole out from the center.
     
  9. xokia

    xokia Active Member

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    I use breakable servo arms so had to drill a hole. I think it was 2nd hole out from center. But doesn’t mean much your arms could be different. I’ll measure it when I get home.
     
  10. murankar

    murankar Moderator Staff Member Armed Forces

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    Running the stock arms that came with the kit.
     
  11. murankar

    murankar Moderator Staff Member Armed Forces

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    Tonight will tell if I made a good choice.

    I changed the tail blades back to the 50mm. Fingers crossed.
     
  12. xokia

    xokia Active Member

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    215325E3-06DB-4C70-8353-33DFB8EE878C.jpeg
    Sorry forgot to measure. I'll try and remember tonight. I do recall reading in the tuning section for my FBL controller that you had to ensure you had enough mechanical gain. If not then the tail was not precise enough.

    I am using the 50mm blades
     
    Last edited: Mar 21, 2019
  13. murankar

    murankar Moderator Staff Member Armed Forces

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    So I did switch the blades out for the 50mm and ran six flights today. It was tough considering the wind was really bad near the end.

    Mikado Vbar Neo 6.0 with Pro Features Enabled
    here is where I am at on my setup (These numbers are not final ):

    Headspeed: 3500 3700 4000

    Head setup:
    Expo: 20 | 20| | 20
    Style: 90 | 90 | 90
    Agility: 100 | 100 | 100
    Gain 90 | 70 | | 70

    Tail Setup:
    Expo 60 50 50
    Rate 100 100 100
    Tail Gain: 60 45 45


    Tail Optimizer
    TC Coll 50 Side A 10
    TC Cycl 6 Side B 91
    Zero Col 0 Optimizer On

    Tail Expert
    Accel 43 Stop Gain 25
    P Gain 65 Stop Gain 25
    I Gain 60 D Gain 0
    I limit Off I DIscharge off


    Tomorrow I will be testing out the new servo arm setup. Manual want to have the bal to center on the tail at 7.5mm. I was getting to much tail kick and having to add way to much in to the parameters. So I moved the ball out to 10.22 mm on the BK servo arms that cam with the 3005 tail servo. Cross fingers and hope the bast happens. My Guess is that TC Coll will drop and over all gain will drop. My next hurdle will be with the P and I gains.

    xokia:

    Thanks for the input. I will be testing out theory tomorrow. Hoping the mechanical gain helps on this setup.
     
    Last edited: Mar 21, 2019
  14. murankar

    murankar Moderator Staff Member Armed Forces

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    Just found a few things to try on Vstabi.info:

    In the Vbar Neo Gov settings under Expert
    set collective add to zero (for my referance it was at 30)
    set cyclic add to zero. (for my referance it started at 10)
     
  15. murankar

    murankar Moderator Staff Member Armed Forces

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    Just so I am tracking everything I have done so far:

    To night I rest the the initial setup to make sure I am at a good mechanical setup. Swash re-leveled, blade grips re zeroed. Wiped out the auto trim numbers. Now its time to go in and reset the gains back close to what is stock.

    Over view:
    Reset the ball link on the tail servo to 10.22 mm
    Zeroed out the Governor Pre comp on the tail and on cuyclic
    Set set the mechanical setup
    Reset the gains.

    Went through and reset everything back to stock or close to it.
     
  16. xokia

    xokia Active Member

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    Can’t find my calipers or I’d measure for you. Snapped a photo though.
     
  17. murankar

    murankar Moderator Staff Member Armed Forces

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    This morning I got the auto trim done. I might have to tweak the numbers a bit but its trained out.

    I got the tail kick almost eliminated but I still need to get the tail gain dialed in. If I hold it in a hover its fine, but as soon as I do a climb out it starts to wag/shake. If I drop the gain the tail feels all mushy and does a slow wag. I am thinking the P gain may need dropped a bit.

    I would say that by the basic tune document by Mikado works. Now to solve the tail wag.
     
  18. xokia

    xokia Active Member

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    8.5 mm center to center for the tail servo is what I have.
     
  19. murankar

    murankar Moderator Staff Member Armed Forces

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    I got some great news after today's tuning flights. Before we get into the tuning I will say that the last days has been the challenge to fly. When your heli has to tilt 45 degrees into the wind to hover its to windy. Yes I flew in winds that I should have said no to. Left with one heli and came back with one heli. That goes to show the quality in electronics. If its the same tomorrow I will get a video of it. I will at some point post my settings so far later on.


    This process applies to Pro features and not the basic Neo

    So I had a bunch of numbers to adjust. First I had went into the Neo governor and adjusted the gov gain to zero. I was not sure where to find the I gain so I left it alone. After doing this step my gov gain ended up at around 25.

    Governor Setting after this step:

    Gov Gain: 28 28 28

    Gov Expert
    Collective Add 10
    Cyclic Add 3
    Collective dynamic 0
    Basic Throttle 50
    P lim - 20
    Integral 20
    P Lim + 20

    Tail Setting after this step:
    Expo: 50 50 50
    Rate 100 100 100
    Tail Gain 46 46 46

    Tail Optimizer
    TC Coll 40
    TC Cyc 13
    Zero Col 0
    Side A 11
    Side B 90
    Optimizer On
    Expert
    Accel 50 (piro speed)
    P Gain 70 (stock 80)
    I Gain 60
    I Limit Off
    Stop Gain A 25
    Stop Gain B 25
    D Gain 0
    I Discharge Off​

    Rotor Head setup
    Expo 20
    style 90
    Agility 100
    Gain 70
    Rotor Head Expert
    Elev PreC 10
    Paddle Sim 20
    Heli Size 32
    Integral 60
    Pitch Pump 10
    Cyclic Ring 85
    Optimizer 46
    Optimizer On
    Now its time to go and fly. I still need to find out what some of these Neo specific things do; i.e Paddle Sim and Pitch Pump. Heli Size is also a Mikado thing, it defaulted to 32 but that is for a 450 class heli. I am going to read up on that also. I think I might make a Quick reference guide for this. I have to keep googling the stuff when I am at the field.

    All of this info should apply to all Mikado units and any clones out there. So if your flying a Kbar, FuBar or any other derivatives of this unit then you will be able to use this info also. One thing note: I do not believe the clones have Pro features available. Its been 4 or so years since I flew my Kbar so I don't remember. Any feed back on this post it and I will add it to this.


    xokia: Again thank you for your input. Its been useful
     
  20. murankar

    murankar Moderator Staff Member Armed Forces

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    Wow what a day so far. So I have 4 flights in 2 of which are on the oxy 3. At this point it appears that my numbers are working for a starting point. Tuning must be done from there biased on the flying style.

    I have been lazy flying at 3500 rpm and 3700 rpm. From what I have seen so far at 3700 rpm I loose about 20 to 30 seconds of flight time. 5 minutes at 3500 leaves about 28% left and that same 5 minutes on 3700 leaves about 19%. So keep that in mind while setting up your banks. I think I may keep a 3700 bank and 2 3500 banks. More to come as the day progresses.
     
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