HS 748 issues

[forthbridge]

Hi Fraser -

I use a Logitech attack 3.. Generally, It's set after T/O to around 90% of max, and from there I finely adjust climb rate/speed in conjuction with f2/3..... I suspect it is the throttle taking a reading from the stick - what's (not hard to do) confusing me is why I'm only seeing it now - as basically I fly the same way on approach as I always have - although I have been doing quite steep (compared to normal) descents recently (about 1800 f/m which is steep for me in the 748).... :think:

EDIT:

Having toyed around, it's *certainly* the throttle kicking in causing this (I've not actually managed it 'myself' as I always feed the power in and bring it back slowly) - but a couple of slides of the throttle and the props feathered. I'll need to do a couple of flights and note exactly what is happening immediately before AP switchoff, and see if I can eliminate this prob..... 1500ft isn't the time to be mucking around with the engines :roll:

**EDIT 2: Seems to be more likely to happen below 120kts...

[DaveB]

Good point Fraser.

None of my joysticks/throttles/yokes et-al will allow this either. Whatever setting was used on the AP remains in force when the AP is disengaged.. this on any/all of the models I have that have AP. On models like the T3 that have speed control (ie, you dial the speed in).. when the AP is disconnected, the model will still fly at the speed/settings previously held by the AP.. regardless of what position the throttles are in (which is usually on quite a high setting on that aircraft as AP is engaged while in the climb) so I have to physically move the stick throttle to gain manual control of the throttle.

Never seen or heard of a stick that will regain throttle control under these circumstances but there's always a first time ;-)

ATB

DaveB :tab:

[TSR2]

Hi Jim,

What you need to remember, as Fraser has touched on, is that the control on the keyboard, cannot input to the control on the joystick. so if the joystick is on one setting and you start using the keyboard, the joystick will not know where the throttle is on the model and so will (depending on the type of joystick) resend its signal. I'm assuming this is a digital joystick, as my Microsoft one only sends a signal when you touch it, as opposed to some digital ones which will continually send a signal.

[airboatr]

Hi Jim

Just curious, if you are in fact able to control the engines rpm with the throttle levers manually,
when your auto pilot functions Are turned on.

I have had props feather when I pull down on the levers to quickly And have seen the genies kick off as well.
Just wondering if kicking off the auto pilot is de-throttling the engines too quickly.
Because the lever position is at the minimum manual setting….something like that maybe?

Joe

hey thanks

[forthbridge]

Hi Guys


Right, had a quick fiddle. I'm going to avoid using f2/3 for the next flight... I think as mentioned, when I disengage the AP, I don't actually move the stick throttle immediately (As throttle is already 'set') - but in the process of me lifting the stick and taking control, I must be resending the 'last' input from the joystick throttle back the the A/C - this is what's sending the RPM dizzy..... it seems to do this with any stick input (elev trim for instance) thus it's irrelevant that I'm not touching the throttle..... I'll see if using the stick throttle throughout the flight makes any difference.....

[DaveB]

Hi Jim..

TBH.. I keep 'fine adjustments' to a minimum with the 748. As soon as I'm established in the climb, I set between 14000/14200rpm and leave it there until the BOD when I'll throttle back for descent. The only time I use keys for throttle is on aircraft with reversers as I don't have a button assigned on the stick I'm using

Is this stick you're using a new one??

ATB

DaveB :tab:

[forthbridge]

HI Dave,

Yup - the stick is relatively new - TBH, I have the 'key' habit from the old stick - the throttle ay have been playing up for long enough and did not give very fine (or rather fine enough) control for my liking, and so I got into the habit of using F2/3 while airborne/for taxiing - but I suppose I should actually use the throttle on this stick and see how it goes....

[DaveB]

Okey doh Jim.. let us know how you get on ;-)

ATB

DaveB :tab:

[forthbridge]

HI Guys

Seems to be solved - so thanks to all for the tips - it seems to (for some reason) not cause any issue if I leave the stick throttle *fully* open - and then release the AP after using f2/3 - but if it's about 70-80% , the throttles seem to go to full power then back down to whatever the stick is set to - causing the feathering. Initially I gave it no thought as it was happening before I touched the stick throttle.. but it seems sorted now

I have also realised that my f2/3 habit has been greatly reinforced by my umpteen tries to get a '10 to the falklands - as I constantly fiddle with the throttles that way to decrease fuel flow as low as I can get it - and it's become a habit :roll:

[DaveB]

Glad you got to the bottom of it mate ;-)

ATB

DaveB :tab: