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Dangers of slow trim


mazzy1026
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Hi All...

Would you consider it dangerous to fly under power with trimmers fully in (slow)?

I'm on a Synthesis 34, and normally take off/land according to what I was taught (and what it says in the manual) at or above (faster) zero, depending on the wind.

My style of flying at the moment is slow, steady and high - taking in the views. Therefore, I normally cruise around between zero and 2 (need a fair bit of power to maintain level flight on full speed).

Experimenting whilst airborne a few nights back (and enjoying the tremendous speed difference when on full fast trim) I tried pulling them all the way in to slow. I noticed a remarkably easy climb, with much less power than I am used to. My first instinct was to wonder why it wasn't my policy to always climb with the trimmers pulled fully in (like I hear so many other pilots doing, who will take off and land with nothing else for "ease"). But after some discussions and thinking about it a little more, it has become apparent that it can actually be dangerous to fly under power, when on full slow trim due to higher angles of attack and stall potential?

I'm asking this after seeing a couple of recent collapse videos (which are for no apparent reason) and in my somewhat naive quest to believe that a wing just doesn't collapse for nothing, I'm trying to eliminate all possible factors - hence the question about slow trim 8)

Cheers,

Lee

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Hi Lee,

I fly a ReAction and that can be flown at all trimmer settings under power.

I have a copy of the Sythesis manual and it states:

First Flights

In order to get familiar with your wing we recommend flying with closed trimmers at first (red area), because in this configuration Synthesis behaves as a standard wing.

Just be aware of 'Dangers of slow trim' as you posted, keep the climb angle shallow and don't turn violently at slow speed.

Cheers, Alan

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Hi Lee. I fly a 34 synth and the hand book is as Alan says, I've re read through it again and basically it's telling the wing is standard at fully closed trim and the trim range gives you the benefits. However it's recommended a 0 setting for powered take off and full closed for free flight.

Personally I take off on 0 - 2 wind depending and climb out no problem. I then let the trimmers out for speed an stability.

Given taking off at 0 and the good climb you get why bother messing about pulling them in to climb to then let them out. Also when first landing I pulled them all the way in for a slow landing. But now I leave them out a touch as in take off as you get a better brake response for flare and comes down a bit quicker.

The synth is pretty rock solid on slow but do everything slow as you let the trimmers out it gets better and you can give it more stick.

Lee.

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Thanks chaps - interesting...

I think what I'm doing seems the way forward: takeoff and land on zero or above, and don't climb on trimmers all the way in (although I'd question it being actually dangerous).

Is it fair to say that the wing is less stable (or more susceptible to collapse) the more you pull the trimmers in? I ask this mainly because of the selling points of reflex, and the fact that you're naturally going slower with trimmers in.

It's at this point I would wonder, what's the best trim setting for "throwing it around" a little? In reflex mode, you're not suppose to use the brakes - so at what point do you achieve a balance of wing stability (based on trimmer setting) and application of brakes, given said setting?

Cheers,

Lee

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If you have a look around the search on the forum I think similar to this has been discussed before. From what I can remember there is a school of thought saying you shouldn't use you're brakes on full trim as brakes change the shape of the Wing and cancel the reflex shape. Hence the alc balls on the synth for steering in full trim. That said if you low you want the brakes in your hands!

I'm not experienced enough to say one way or the other.

What I do know is on full trim the alc works great so does just hooking the line with your finger.

A lot of more experienced pilots use brakes in full trim and have no issues.

From what you've said about your type of flying ie high and relaxed( same as me) let the trims out and relax with alc steering it really is good, you can still pull some nice positive turns this way and have benifit of max stability should you hit a few bumps.

I've only recently started coming down for a nosey and tend to put the trim out half way way to keep a nice speed and reasonable climb rate and use the brakes. The amount of pull needed increases to get a nice turn but I've noticed no ill effects.

Cheer Lee

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I have been reading all this with great interest. I am on the same wing (Synth 34), and after my first XC flight last weekend, in which I didn't touch the trimmers, I guess my next foray will involve some experimentation here. Certainly looking forward to resting my arms a bit!

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Pat - yes, let them out and see how amazing it is. Also, give the tip steering a try - you will love it! As long as you keep your trimmers the same on each side, you'll be fine!

Lee - yeah for me it's a balance of not requiring too much power vs speed and trim setting. I don't wanna rev the nuts off the Moster too much!

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So talk me through it. You park the brakes? Is it important to depress the trimmer ratchet straps simultaneously or do you let them out one at a time. What's the sequence when you come off them?

Edited by Guest
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Patrick,

I will give you a full brief before you cary out that task :-)

Non of the above is incorrect but I would opt for both at the same time, or a little each at a time rather than fully out one at a time. :-)

SW :D

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Looking forward to it,Simon.

Just need this breeze to die down

I'd worked out doing one at a time would make you turn, till they were even,but I had no idea how pronounced the turn might be.

park the brakes, let the trimmers on one side out half way between where they are and full, then the other side the same, then the first one all the way then the second all the way, don't be too afraid of using the brakes with some trim out, on my Nuc I tend to put the trimmers out to about 7 for normal buzzing around and still use the brakes, if I let them out all the way I will only use the tip steering, if you aint got tip steering on your wing just reach up and grab the outer (stabile) line.

pulling the trimmers back in is the reverse of the above.

if you are looking to start using your wings performance more you mite want to start landing with different trim settings also.

above all else, have fun! :D

Dave.

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Dont take off on full slow as you may find the wing will try to hang back, reducing your ability to get up to the desired airspeed for take off

There is no problem with flying in full slow, but be mindful that you maybe creating more drag at this setting and may find that neutral or above may give more speed with no more power required (wing loading dependent)

I would recommend only landing with full slow in very light wind conditions. Above 6mph use neutral or above as this will guarantee there is surplus airspeed in the bank if the oncoming wind speed suddenly drops or there is a chance of rota.

Airspeed is king

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Sort of related.

What would be involved in changing the old style ALC Balls on the Dudek Synth to the new style small D handles (not sure, but did they have keep magnets as well?) that I saw on a brand new Synth recently delivered to Membury.

Is it even worth it?

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This is correct but they have now gone back to the no balls version as standard.

I think many of the schools were asking for it from the day it came out..(for teaching and ground work they are/were a pain) IMO.

SW :D

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Apco state that their wings are not certified at all if you use the trimmers. Which seems to imply that if I take off (or fly) with the trimmers on, then my Apco wing is not certified as safe.

Having said that, good practice appears to suggest that in higher winds it is better to use some trim when taking off and landing so that the wing doesn't hang back too much (on take-off) and reduces your chance of being blown back (on landing).

Two contradictory pieces of advice.

Dom

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