Are 'recommended throws' really necessary?

[paul devereux]

Just wondered. I've Googled this and not come up with anything definitive. If you have a beginner/sports plane, do you really need to set the recommended throws? I was wondering that if you flew a little less fast, and were gentle with the controls, full control movement would be okay, as you wouldn't use it fully? The reason I mention this is, as I mentioned on another thread, I learnt to fly (well, not to crash) on a little Hobby Zone Cub, 23 inch span with a SAFE gyro and three positions, beginner, intermediate and expert.  I actually found the 'expert' mode easier to control the aircraft (this is a high wing model which is quite different to the 400mm war birds that need gyro), as it didn't keep trying to do its own thing. And of course it is so light a power-off 'crash' does no harm.

 

I'm about to launch a Multiplex Merlin- would I be okay with the throws as they are out of the box, do you think?

[john stones 1 - Moderator]

I would say so, Yes. Your flying a somewhat unknown quantity first flight with a new model, get it trimmed out, learn it's character, then adjust to suit your taste/style. It's a starting point.

[Graham Bowers]

I'm slightly confused as what's meant by "out of the box" in this context. I've not owned one, however it seems the Merlin needs to be built, and the instructions even specify which holes on the servo arms and control surface horns to use.

 

Really need to use the recommended throws? In my opinion it depends on the skill and experience of the pilot so if being gentle on the controls and good speed management have been learned, there is a better chance of managing  with control throws greater than specified by the manufacturer. I've reduced the throws for clubmates who were finding their models a handful and have never found the need to increase them.

 

I always start with recommended CoG and throws with my models on full rate and around half on low rate, with around 30% expo on each. Maiden launch on high rate. Adjust to suit. Each to his own.

[MattyB]

1 hour ago, paul devereux said:

Just wondered. I've Googled this and not come up with anything definitive. If you have a beginner/sports plane, do you really need to set the recommended throws? I was wondering that if you flew a little less fast, and were gentle with the controls, full control movement would be okay, as you wouldn't use it fully? The reason I mention this is, as I mentioned on another thread, I learnt to fly (well, not to crash) on a little Hobby Zone Cub, 23 inch span with a SAFE gyro and three positions, beginner, intermediate and expert.  I actually found the 'expert' mode easier to control the aircraft (this is a high wing model which is quite different to the 400mm war birds that need gyro), as it didn't keep trying to do its own thing. And of course it is so light a power-off 'crash' does no harm.

 

I'm about to launch a Multiplex Merlin- would I be okay with the throws as they are out of the box, do you think?

It costs nothing to setup a few rate switches and/or (ideally switchable) expo on your TX, and literally every transmitter (other than the cheapest of RTF packaged TXs) has this functionality. Why on earth would you not set it up? Those of us who have flown for a while know you can never weight things too far in your own favour on a maiden flight. That means triple checking via calculation that the CG is logically set (not just going with what the manual says) and setting up your TX to give you flexibility in terms of control throws are probably the two biggest things you can do to increase your chances of success 

[leccyflyer]

What they said. 🙂

 

Start with the recommended throws and CG position as a good starting point and take it from there. I'd add that with most models these days it pays to do a little online research on CG position particularly, as there are numerous instances where the CG stated in the manual has been shown, in practice, to be sub-optimal. Like the gents above have said, if possible, set up rates and expo giving a series of options - personally I use 35% expo with rates on a three position switch at 100%, 70% and 55% for my maiden flights and adjust accordingly afterwards.

 

It's a very common occurrence to see models arrive at the field for a first flight with massive throws that then do need taming for a maiden flight. If there is a degree of tail heaviness built in, by a reluctance to add any additional weight to balance properly, that it going to stack the odds against a successful maiden flight. Careful set up before bringing the model to the field, using the recommended throws is very much the preferred option and is much better accomplished in the calm environment of the shed, with plenty of time, rather than in the excitement of preparing for a maiden flight at the field.

[Paul De Tourtoulon]

After going into the buy now artf 'modelling', I have had a lot of hairy moments, I go with the minimum throws to start with and sometimes a dual rate or two but normally I have found the minimum throws for a first flight more than enough.

[paul devereux]

8 hours ago, Graham Bowers said:

I'm slightly confused as what's meant by "out of the box" in this context. I've not owned one, however it seems the Merlin needs to be built, and the instructions even specify which holes on the servo arms and control surface horns to use.

 

You are right. I bought it from EBay built but never flown, so I meant "untested" in a way. Sorry for the confusion.

[Frank Skilbeck]

The recommended throws are a good starting point, and with a Multiplex model are usually pretty spot on.

 

I remember many years ago I had a CAP aerobatic model I test flew it on the recommended elevator control throw and felt it could do with more, on the first loop it flicked out at the bottom, a high speed stall at a high angle of attack, fortunately I was a couple of mistakes high, so learnt to be careful on the elevator stick. But obviously the designer had found this and limited the elevator throw to mitigate for this.

 

Also on gliders it's often better to follow the recommendations for aileron differential.

[Jon H]

I usually ignore recommended control throws as, in my experience, they are always massively too high especially on elevator. This leads to an over sensitive model which is then made less sensitive with shed loads of expo. This ruins the harmonisation of the controls so i will always recommend ditching the expo, reducing the rates to give lower movement, and then if you absolutely have to, add a small amount of expo back. expo should always be the last thing you do, not the first. 

 

 

[David Davis 2]

Hi Paul, with all of my models I set the controls to the designer's recommendation but use the rate switch to cut the travel to 66% and I add 25% expo.

 

I have flown the Merlin and it's a beautiful model to fly but perhaps a bit "hot" for a novice. If I were you I'd set up your radio in the same way that I set up mine, 66% travel on the rates and 25% expo, then, as you're a beginner Paul, I'd give the model to an experienced pilot for the first flight then make adjustments accordingly.

 

I know it's not the same thing but I've just finished building a 1957 vintage model called the "Guidato." I flew it for the first time on Monday. I plan to use it as a basic trainer with elderly novices on the buddy box. The rudder proved to be very sensitive even at 66%. I plan to reduce the rudder travel to 50% with the rates switched in.

[Cuban8]

57 minutes ago, Jon - Laser Engines said:

I usually ignore recommended control throws as, in my experience, they are always massively too high especially on elevator. This leads to an over sensitive model which is then made less sensitive with shed loads of expo. This ruins the harmonisation of the controls so i will always recommend ditching the expo, reducing the rates to give lower movement, and then if you absolutely have to, add a small amount of expo back. expo should always be the last thing you do, not the first. 

 

 

Absolutely excellent advice Jon - something I've taken on board from you when you've mentioned this before.

It's surprising just how little control movement is needed to maintain positive control and this is often not realised, particularly by beginners, who think that "I'll need stacks of control throw in case of an emergency".

[Graham Bowers]

1 hour ago, paul devereux said:

You are right. I bought it from EBay built but never flown, so I meant "untested" in a way. Sorry for the confusion.

Nothing to be sorry for. Hopefully the comments received will prove helpful.

[Nigel R]

3 hours ago, Cuban8 said:

"I'll need stacks of control throw in case of an emergency".

 

Whereas in reality... stacks of control throw often cause an emergency...

[Jon H]

20 minutes ago, Nigel R said:

 

Whereas in reality... stacks of control throw often cause an emergency...

 

You beat me to it! 

[Geoff S]

In fact, on a tricky 'trouser clip' maiden I've sometimes asked a companion to flick the rates switch because things were too sensitive and I daren't move from the sticks.  I've never felt the need to increase throws but occasionally had the desire for more movement which isn't absolutely necessary.

 

I like to use recommended throws where they're available.  It's one less thing to worry about - especially on a model I've spent many hours building.

[John Stainforth]

I usually put in the recommended throws (with the servo movements at "100 %"), and then program one or two lower rates settings (depending on transmitter) to say 40 and 70 % of those rates. I start with the lowest rates for a maiden, but ready if really necessary to instantly switch to higher rates. Then experiment with the higher rates and go from there. Usually, much of the first flight is taken up with flying the plane with one hand and making trimming adjustments with the other (or, better, with a helper). I agree with Jon (and many others): no expo. Expo softens the central position, but if one over-controls one is really in trouble.

Edited February 15, 2023 by John Stainforth

[GrumpyGnome]

If there are recommended throws etc, I'd use them.

 

I put these as mid rates then add my own high and low rates - usually 25% less and more; if expo is recommended, I'll do the same with differences of 5% extra for high and less for low. 

 

Once I am happy, I remove the different rates, unless they are linked to specific flight mode such as landing, i.e. I don't keep multiple rates for the sake of it, and don't have them activated by 'their own' switch. Some, not all, models have expo - but 25% max (except my indoor 3D planes).

 

Expo is interesting... one of our members never reduces throws where it's obviously excessive, just increases expo..... some of his outdoor sport/scale planes have expo rates and throws suitable for an indoor F3P machine.

[Jon H]

21 minutes ago, GrumpyGnome said:

one of our members never reduces throws where it's obviously excessive, just increases expo

 

This is absolutely the wrong approach. I have been handed so many models setup this way because they 'wont land' or wont do some other thing. Once i wipe out all the expo and chop 50% or more out of the rates the model is all of a sudden a joy to fly. 

 

My acrowot xl recommended loads of expo in the blub but i have none. Its rock solid, not at all twitchy and a joy to fly. All i did was reduce the rates. 

 

For normal sport/scale/aerobatic flying expo is the cherry on top, not the start point and i am yet to find a situation where i have needed more than 10%. Its a powerful tool, but sadly misused and misunderstood. 

 

 

[john stones 1 - Moderator]

I've never understood expo either, I want the model to tell me if I am clumsy on the sticks, nor do I want every model having the same feel.

[John Lee]

I like expo. I like the soft feel around the centre but having full throw available as required. But that is me, and I appreciate that other tastes differ and that's OK.

 

I do find that both Multiplex and Sebart recommended throws and mixes are invariably pretty much spot on. I'm quite meticulous with my set up using a CG gauge and AT Wizard angle and throw sensors. With those and an hour or two on the bench maiden flights have always been none events and I've never needed more than a couple of % trim adjustments, even with 4 servo wings and multiple mixes.

Edited February 16, 2023 by John Lee

[Geoff S]

I fly mode 2 but have a partially paralysed right hand because of a spinal injury (I can't easily move my fingers individually) and I find expo useful by reducing the inevitable cross-coupling of aileron and elevator.  I also find it useful on rudder by reducing the effect on take-off whilst still allowing full movement for manoeuvres like stall turns.  It does have its uses.

[Jon H]

17 minutes ago, Geoff S said:

I fly mode 2 but have a partially paralysed right hand because of a spinal injury (I can't easily move my fingers individually) and I find expo useful by reducing the inevitable cross-coupling of aileron and elevator.  I also find it useful on rudder by reducing the effect on take-off whilst still allowing full movement for manoeuvres like stall turns.  It does have its uses.

 

In cases like this i cant fault its use, my comments are a generalisation rather than addressing the specific need of an individual. For most pilots though, a little practice to eliminate cross control is better than trying to cheat. 

[leccyflyer]

26 minutes ago, John Lee said:

I like expo. I like the soft feel around the centre but having full throw available as required. But that is me, and I appreciate that other tastes differ and that's OK.

 

I do find that both Multiplex and Sebart recommended throws and mixes are invariably pretty much spot on. I'm quite meticulous with my set up using a CG gauge and AT Wizard angle and throw sensors. With those and an hour or two on the bench maiden flights have always been none events and I've never needed more than a couple of % trim adjustments, even with 4 servo wings and multiple mixes.

Yep, I like expo too - I used to have 40% and was very comfortable with that, but have reduced it somewhat on most of my models. Although full rates are there for aileron and elevator the only time I use them is for take off with some models which have a tendency to nose over and need every bit of up elevator that they can use to stop that. The high rate elevator switch is activated right after take off, along with the Gear Up switch. It's a matter of personal preference whether to use expo or not and personally I appreciate the smoothing of the controls that I perceive when flying.

 

We were discussing the other day how flying the tiny 50g Volantex models with stabilisation really makes you notice when you go back to a normal sized model without such aids. To get the Volantex models manoeuvering it's sticks in the corners stuff and that muscle memory does come across to your proper models for a few seconds. 🙂

[MattyB]

We have talked about this expo vs rates discussion many many times here before - here's one good example...

For some reason it seems to be one of those polarising topics, but despite the absolutes espoused by some in this thread both can be used effectively to get a good result. I do agree that getting the rates in the right ballpark on a beginner's aircraft is helpful, but saying "no expo" or "never more than 10%" as a blanket rule for everything is a bit silly IMO. If you want to use it do so; it's just another tool in the box, and for some classes of aircraft (i.e. 3D or fun fly) having high amounts of expo is completely normal and very helpful.

Edited February 16, 2023 by MattyB

[Jon H]

This probably echo's what i wrote before in that other thread and i dont want to go off the rails so this will be my last comment on the subject unless there is a specific question.

 

As i said, my comments apply to normal sport, scale and aerobatic models and 3d stuff is different and i mentioned that as well. 

 

Still, its a fact that none is required in most cases and 10% will satisfy a very large proportion of cases where it is needed. If it wasnt true, i wouldnt be able to do it 😛 

But, that does not exclude cases like 3d or whatever. I only mention 10% as someone with 65% expo in their Spitfire might see it and go 'huh, why do i have so much if this chap's warbirds fly with none?' They then look at what it is they are doing, make changes, and get a better flying model as a result. This exact thing happened with a friend's H9 Spitfire. 65% expo...it was awful. 

 

Also another objection is it makes people lazy. As a beginner, instead of learning a new skill (like pulling the stick straight) they try to cheat and progress faster and this does nothing to make them a better pilot and in fact makes the whole thing more difficult long term as their core skills are lacking. Admittedly this is in part due to tedious flying in circles during training boring them to tears, so i get round that by going straight for basic aerobatic training once basic circuits are mostly ok and well before takeoff and landing training. A loop will easily show if you are pulling the stick wonky, and doing a loop is something even non flying people can recognise as some sort of achievement. So they dont get bored, and they move their sticks straight. Its a win win. 

 

Of all the previous expo advocates who's models i have adjusted to my way of doing things none of them have gone back to they way they were before. They all admitted they flew better and were easier to control, much to their surprise in many cases. Perhaps i am just a complete ninja when it comes to model setup? or i am the Eric Brown of model flying and do things others cant? but i dont think so. For the most part I dont think i do anything anyone else cant with the right instruction. I think most just followed a path and got as used to it as best they could. It just may not have been the right one. 

 

Anyway I am not saying it is not a tool with no use at all. 10% sorted out the ailerons on my stampe. Just that it is very much over used, incorrectly used and is normally the first port of call for adjustment when i really should not be. 

 

Its a snowball effect too. Reduced rates mean you can use a more aft c/g. This means less lead carried, a lighter model, perhaps a model that will not sit on its nose every 2 minutes as its nose heavy etc. (might be worth looking at leccyflier 😉 ) 

 

I only have a small box to write in and finite amount of time to write a post and so many of the things i recommend come about because of a spiders web of contributory factors. I cant pour all of it on the page as i would be here all day. Half the time i am not even aware of all the links myself and there's an 'oh yea, that is a thing because of this' moment when i realise one. 

 

So i resent the implication that i am a bit silly. i just have to over simplify everything to make it fit in a post and there is way more to it than 'booo expo bad'. 

 

 

 

 

Edited February 16, 2023 by Jon - Laser Engines