Flaps. Servo speed.

[john stones 1 - Moderator]

What's your thoughts on reducing servo speeds when deploying flaps ? Never bothered before as I've only used them rarely, model is a Funky Cub, quite large flaps, not concerned about pitch change when deployed, just curious what regular users think.

[Chris Walby]

Not a bad thing to deploy flaps/gear in a more scale like way...Can't say it looks that impressive when a warbird comes in and the gear flicks down followed by the sound as they hit their stops.

My SG mossie pitches up with flaps and down with the gear so I do both at the same time over about 4 seconds, makes my life easier and looks nice.

[Simon Chaddock]

john

Both my flap equipped planes (they have huge 'big angle' flaps) use my 35 Meg Futaba Tx simply because it has knob which I can conveniently reach with the side of my fore finger whilst keeping the thumb on the ail/elev stick.

Move the flap, adjust the throttle then adjust the trim as required. Repeat until the desired effect is achieved. You just have to remember how far you have turned the knob although once familiar with the plane you can more or less tell the flap setting by how it behaves.

Works for me.

[Frank Skilbeck]

If they are on a proportional control then you can control the speed with a slider/knob so no, but if on a switch then having a control slow smooth things out. Note beware of servo slow as if you have a mix to say retrim the elevator, the flap servos may move slowly but the trim change may be instantaneous.

[John Lee]

I now have 11 models of all sorts from a FunCub to BAe Hawk equipped with flaps. I have adopted a standard of a 3 position switch - up, take off & landing settings slowed with a 1.5 second transit both up & down. Elevator compensation where required runs at the same speed, easily set up with my Jeti radio.

Works for me.

[Cuban8]

The twiddly knobs on trannies I find to be hopeless for anything, don't know how anyone manages with flaps on them.

I have flaps on a 3 pos switch on my DX8 and slowed by the setting provided within the programming. Charming young lady within the box tells me (quietly) where they are - landing, up/down etc. Having flaps deployed slowly rather than banging straight down does seem to help with reducing pitch change, or at least making any change more manageable to trim out if required I find.

Edited By Cuban8 on 10/07/2020 20:52:57

[David Ovenden]

I always have flaps controlled by the LH side slider. I find I can control the speed of deployment easily that way. And I can reach the slider without taking my thumb off the stick. My radio won't apply reduced servo speed to the elevator mix component (as Frank rightly points out) so rely on moving the slider slowly for a scale effect.

[john stones 1 - Moderator]

I had forgotten all about the sliders, JR 9x, how do I bring those into play ? It don't say much in the manual, Is it just a matter of Inhibiting the flap switch and activating an Aux one ?

[David Ovenden]

John, I use JR radio. Both my 10X and XG14 have side sliders (ike the 9X) and it is just a case of assigning the flap channel to the slider and inhibiting the flap switch. I don't rely on the pre-set auto flap mix but set up my own mix as needed.

[Richard Clark 2]

Posted by john stones 1 on 10/07/2020 18:14:03:

What's your thoughts on reducing servo speeds when deploying flaps ? Never bothered before as I've only used them rarely, model is a Funky Cub, quite large flaps, not concerned about pitch change when deployed, just curious what regular users think.

I don't bother. Nobody ever does, me included, on a real plane. So if it's 'manual' it is near instant, if it is powered it depends on the speed of the hydraulics.

Why? Use servo slow you are dealing with a varying situation over time. That just makes things more difficult.

(It's even worse on take off with a propeller plane. Open the throttle slowly you are dealing with a varying torque and prop wash over the fin/rudder and trying to keep straight at the same time. My RAF instructors said to slam the throttle open so your are dealing with a fixed situation. You still have to reduce the rudder offset as you gain speed but at least it's linear. Try it on your Junior 60 and I guarantee you won't go round in circles as so many do )

PS: Put the flap on a 3 position switch. Up, half and full. There is no point in putting  them on a knob or slider, it just induces more unnecessary variables.  A switch 'sets up'  a  fixed situation and you don't have  to do anything  until your flare  for the actual landing.  Too many adjustable things just causes  pilot induced oscillations.

Edited By Richard Clark 2 on 11/07/2020 07:05:37

[Peter Miller]

That is one of the reasons that I love my Hitec Aurora 9. The flap lever falls under the left forefinger allowing the flaps to be operated at a steady pace while still maintaining full throttle control.

Of course if you operate the throttle with finger and thumb you have a problem but there is a matching lever on the right side.

[john stones 1 - Moderator]

Thanks David.

[Bob Cotsford]

I've adapted the standard of setting flaps up on the LH side pot which I can reach easily while keeping my thumb on the throttle stick. I shall keep my thoughts on throttle control to myself.

[john stones 1 - Moderator]

Think I'll set up the same Bob, 9x is a well laid out box, sliders are in easy reach.

[Martin McIntosh]

I use the servo slow feature and a three position mode switch on my flap equipped models, giving half flap for the approach and full before touchdown. It avoids the model jumping up or down suddenly, but on something like a Spit. or Hurri. it is a good idea to have flap retraction at normal speed so that you can flip them up when the model touches to avoid a nose over, if you remember that is.

[Mike Blandford]

Posted by Richard Clark 2 on 11/07/2020 06:49:38:

Posted by john stones 1 on 10/07/2020 18:14:03:

What's your thoughts on reducing servo speeds when deploying flaps ?

I don't bother. Nobody ever does, me included, on a real plane. So if it's 'manual' it is near instant, if it is powered it depends on the speed of the hydraulics.

Well the Cessna I learnt on had electric operated flaps and they were quit slow to deploy.

I have my flaps set up on both a 3-position switch and a slider, with slow on the switch. So I may use the switch to set "up", "take off" and "landing" positions, but have the option of anything in between by using the slider.

When deploying flaps in the air, always reduce the aircraft speed first, otherwise you will likely get a significant pitch change that then reduces as the aircraft airspeed drops.

Mike

[Keith Miles 2]

I fly full size, too. Cessnas have powered flaps with gradual deployment. Pipers are manual with instant deployment. In practice, I find any pitch change is easily controlled in either case as you tend to both feel it and see it and then compensate with elevator automatically before re-trimming.

Of course, you have no “feel” with a model, so I suppose it depends on how much pitch effect a given amount of flap has on a particular model (and you probably won’t know that until you try it) and how much correcting pitch trim is required.

For my first, and currently only, flapped model, I opted for “book” setting and slow two-stage deployment using the timer on my DX9 purely to allow maximum reaction time to make any necessary pitch correction. I’ve only flown it a few times so the experiment continues. Thus far, I have found that I can comfortably control the model with just power and elevator without adding trim or needing a mix.

I suppose, as with other things, it ultimately comes down to personal preference and Tx features although I suspect that gradual flap deployment might be generally preferable on a model, notwithstanding the possible difficulty mentioned if an elevator/flap mix is desired.

[Nick Cripps]

Following up on Frank's comment on elevator compensation, the DX9 applies the trim at the same rate as the flaps move, ie, not instantaneously.

Other radio brands may differ.

[Richard Clark 2]

Posted by Keith Miles 2 on 11/07/2020 12:34:05:

I fly full size, too. Cessnas have powered flaps with gradual deployment. Pipers are manual with instant deployment. In practice, I find any pitch change is easily controlled in either case as you tend to both feel it and see it and then compensate with elevator automatically before re-trimming.

Of course, you have no “feel” with a model, so I suppose it depends on how much pitch effect a given amount of flap has on a particular model (and you probably won’t know that until you try it) and how much correcting pitch trim is required.

For my first, and currently only, flapped model, I opted for “book” setting and slow two-stage deployment using the timer on my DX9 purely to allow maximum reaction time to make any necessary pitch correction. I’ve only flown it a few times so the experiment continues. Thus far, I have found that I can comfortably control the model with just power and elevator without adding trim or needing a mix.

I suppose, as with other things, it ultimately comes down to personal preference and Tx features although I suspect that gradual flap deployment might be generally preferable on a model, notwithstanding the possible difficulty mentioned if an elevator/flap mix is desired.

Perhaps surprisingly I've never flown any Cessna, nor been a passenger in one.

As for the flap to elevator compensation moving the elevator fast when the full amount of the 'slow' flap part has not yet arrived at the mixer so is not yet 'known' by it I don't see how that can happen.

[Keith Miles 2]

Posted by Richard Clark 2 on 11/07/2020 18:47:03:

Perhaps surprisingly I've never flown any Cessna, nor been a passenger in one.

As for the flap to elevator compensation moving the elevator fast when the full amount of the 'slow' flap part has not yet arrived at the mixer so is not yet 'known' by it I don't see how that can happen.

Did I say that or are you quoting someone else? Sorry if I misunderstood.

In my case, I have yet to use a mix, so can’t comment on that at all. First impressions suggested that I might not need it. A club mate has a Hangar 9 Cirrus and I asked him for advice on this issue before I test flew my Super Chipmunk. He doesn’t use a mix either.

[Richard Clark 2]

Posted by Keith Miles 2 on 11/07/2020 21:35:58:

Posted by Richard Clark 2 on 11/07/2020 18:47:03:

Perhaps surprisingly I've never flown any Cessna, nor been a passenger in one.

As for the flap to elevator compensation moving the elevator fast when the full amount of the 'slow' flap part has not yet arrived at the mixer so is not yet 'known' by it I don't see how that can happen.

Did I say that or are you quoting someone else? Sorry if I misunderstood.

In my case, I have yet to use a mix, so can’t comment on that at all. First impressions suggested that I might not need it. A club mate has a Hangar 9 Cirrus and I asked him for advice on this issue before I test flew my Super Chipmunk. He doesn’t use a mix either.

 

It was somebody else, sorry  not to be as clear as I should have been. (To me what he said seems impossible.)

I tend to use a flap to elevator mix (if needed, which it often isn't) because I've got a 'thing' about never using the trims. It comes from my liking for 'mechanically optimising' the model rather than adjusting throws, centres, etc. electronically. During the first few flights of a new model I land and 'mechanically adjust' several times and from then on the trims remains  centralised and never touched.

Edited By Richard Clark 2 on 12/07/2020 07:26:34

Edited By Richard Clark 2 on 12/07/2020 07:34:58

[Frank Skilbeck]

Posted by Richard Clark 2 on 11/07/2020 18:47:03:

As for the flap to elevator compensation moving the elevator fast when the full amount of the 'slow' flap part has not yet arrived at the mixer so is not yet 'known' by it I don't see how that can happen.

Depends how you have done the servo slow, quite a while back on a model I had I'd used an external servo slow/reverser (two flaps on one channel) so the mix went at full speed but not the flaps. Agreed radios I have with built in slow, apply this too any mix too.

[Frank Skilbeck]

Posted by Richard Clark 2 on 12/07/2020 07:25:16:

I tend to use a flap to elevator mix (if needed, which it often isn't) because I've got a 'thing' about never using the trims. It comes from my liking for 'mechanically optimising' the model rather than adjusting throws, centres, etc. electronically. During the first few flights of a new model I land and 'mechanically adjust' several times and from then on the trims remains centralised and never touched.

Edited By Richard Clark 2 on 12/07/2020 07:26:34

Edited By Richard Clark 2 on 12/07/2020 07:34:58

Bit difficult on some gliders which use the flaps and ailerons for camber changes and need different elevator positions for speed and thermal settings, but that's getting away from the topic of this thread.

[Ron Gray]

Slow down, fast up - can get you out of a sticky situation!

[Martin Harris - Moderator]

...or put you in one! Certain setups can result in rapid sink if the flaps are put away too quickly! Fine at 100 feet but at 10?

Frank, if you have a transmitter capable of setting flight modes with independant trims then it's very easy to cater for multiple flap situations.  This is certainly the case with Jeti but I suspect FRSky, Multiplex and higher end versions of the main brands will also support similar functionality.

Edited By Martin Harris on 12/07/2020 16:45:15