Mercury and flaps

  • Hi

    My trim with flaps down in my jet is about 25 clicks nose down from level flight

    Should I turn radio on with flaps down? Flaps up? does it matter for the gyro where "trim flight" is?



  • If it helps this is how I have set up flaps for my Xcalibur jet. Although I use the iGyro SRS.

    FM1 is set to rate mode only. I have a transmitter mix for FM1 switch position only to add a small amount of down trim proportional to flap position - i.e. mix controlled by gyro mode switch

    FM2 Attitude Assist (heading on elevator and aileron for iGyro) . No Mixing

    FM3 Attitude Assist All ((heading on rudder, elevator and aileron for iGyro) No mixing

    FM2 and FM3 are good for landing because you can set a stabilised nose up attitude for landing. FM1 though still allows you to have the aircraft properly trimmed for flaps, although you have to experiment with the mix for properly neutral trim at different flap settings.

    If you power up the gyro with flaps down and the elevator mix active, the gyro will take that elevator input as neutral for all elevator movement. So attitude assist will only work on elevator when elevator input is the same as the mix from the flap when the flap is active or otherwise. Could create some strange effects but in any case there will be no attitude stability with the elevator stick at the centre. ( At least this is how it works on the iGyro - Richard please correct me if I'm wrong - I haven't flown much with my Mercury units)

  • hello, im at the first time to fly my viperjet 2.60mt with powerbox mercury with gps II , software is the last version V9, can you tell me the best setting for fly and for take off and landing, i means what is best to use, rate mode for what? normal flying? and attitude for landing?

  • i don't understand what is this: can you exaplain more clearly? i understand that is set in rate mode, but what mixing you have make for the flap?

    FM1 is set to rate mode only. I have a transmitter mix for FM1 switch position only to add a small amount of down trim proportional to flap position - i.e. mix controlled by gyro mode switch

  • OK, I'll try to clarify...

    You have a three position switch for the gyro mode - per instructions. The usual settings are

    FM1 - Gyro Off or Rate Mode

    FM2 - Attitude Assist Standard

    FM3 - Attitude Assist All

    You only want your flap down trim to be active in FM1 i.e. when gyro is completely off or operating in Rate mode. So you need to have your mix enabled and disabled by the same switch as the gyro mode, so it is disabled in FM2 and FM 3.

    Your simplest solution, at least to start with, is to disable your flap mix completely and then use the Test Fly Assistant as Richard advises. If you use the flaps when FM2 or FM3 is selected (i.e. with Attitude Assist) for take off and landing, you won't need your mix at all.

  • I understand completely what you are saying and i agree with the technicalities

    However, can you elaborate more why you are using "hold" instrad of "rate" mode?

    Everybody around here (florida) seems to agree to fly only rate mode and hold mode is sort of a no-no


  • My advice: why not try it it and decide for yourself. After all there's a switch to let you decide which mode to fly in.

    The PowerBox iGyro gives a very natural feel in any mode - it's the best I've used and why they are in all my models. The GPS speed regulated gain is a fantastic feature, and I suspect, is much more reliable that an airspeed pitot sensor - the GPS wont get dirty.

    There are two things to watch out for :

    1. If you let the speed drop to zero in hold/attitude assist, funny things happen as the speed picks up, e.g. a stall turn. No big deal, it sorts itself out.

    2. If you have hold/attitude assist on the rudder and attempt a turn (without rudder) the tail drags. This is why the manual says to have a mode with just rate on the rudder.

    Its easy to get used to switching modes in flight, but it is one more thing to check at take off, so you don't have unexpected flying characteristics e.g. hold on rudder - it might surprise you when you turn after gaining flying speed.

  • Hello,

    I think that each model equipped with a mercury can have different result, regarding the flight behaviour with flaps.

    Here is my experience with flaps of an Avanti equipped with a mercury SRS V09, and the behaviour was the same with the V07.

    In assist mode:

    - middle flaps (take off position) without any mixing: no trouble,

    - full flaps + "aileron in airbrake" (landing position) without any mixing: strange behaviour. Sometimes perfect, sometimes while in turn or while speed is reducing I can see some strange pitch manoeuver and I DO not want to see these manoeuvers during my final approach. (and I can't modify the elevator gain: if lowered I don't have the knife edge corrections, if increased I have oscillations in normal flights)

    - full flaps + "aileron in airbrake" (landing) WITH elevator mixing: no trouble but I'm aware that I don't have the "assist mode" advantage, as my elevator is far from initial center position.

    I don't have any ballooning during landing, either without gyro, or with rate mode or with assist mode, and with or without mixing.

    My positions are:

    FM1: NO GYRO

    FM2: ASSIST 45% aileron+ elevator, RATE 45%, for rudder, vector thrust disabled

    FM3: RATE 45% FOR ALL; vector thrust at 100%

    My chrono flight is:

    - just before take off (to have all surfaces at 0): FM1

    - take off , all standard aerobatics and landing (with flaps to elevator mixing): FM2

    - hovering or spin or funny manoeuvers: FM3 (I can also land with this position as the elevator mixing is always active with flaps)

    - any suspicious manoeuver or doubt on gyro: FM1

    After some test I finally had the same gains between the V07 and the V09.

    I'm currently using only SOFT behaviour but I think that I will increase a bit the vector thrust behaviour to NORMAL or more, as the Avanti feels unstable in harrier.

    I hope this helps.

    Goord flights

  • thank you

    Without claiming to be an expert at all, here is my experience with my f16 bvm 1/6 scale

    1) v9, all modes in hard

    2) all modes rudder rate about 10% only, otherwise it fights me out of the turns

    3) for normal flying, both rate and assist modes work equaly well (no noticeable difference, elevatir around 20%, aileron around 45%, plane feels solid

    4) for landing mode, flaperons down, tailerons on, I am still trying to figure it out.

    a) the fact that the ailerons act as flaps means that they are off the "zero" and therefore the giro is fading out noticeably

    b) because of flaperons down, i cant use assist mode for landing which i woukd like to try. Maybe I should try turning on the unit flaps down to set the zero there, and use rate mode for normal flight; does rate mode care where the zero is except for the fading out? If not, i could increase gain to compensate. Thoughts?