Jab 160-C trim

[Guest Macnoz]

Hello

 

I wonder if any of you have noticed what I believe is a flaw in the Jab 160 –C Pre Take – Off checks.

 

The Trim Set Neutral appears in “Ground check and run upâ€Â

 

“Controls Full & Free Travel, Correct Sense†appears later in the “Pre Take Offâ€Â.

 

On my craft and I presume all 160’s, stick full back, pulls the trim control lever nose up where it stays.

 

A subsequent Stick full forward does not take the trim control away from nose up.

 

There is no subsequent mention of trim check in the take off checks.

 

If you follow the printed checks in chorological order there is a danger of premature liftoff at an inadequate airspeed and a stall once you come out of the cushion.

 

Maybe this has been covered before or indeed manual revised.

 

I only noticed it myself having come back to my own Jab after interstate experience in a variety of types over a few months

 

 

[Guest brentc]

I wouldn't be at all concerned about this. The trim doesn't restrict control movement, it just adjusts the neutral postion of the control surfaces. If you want to take off you should pull back on the stick - if you don't want to take off, don't pull back on the stick. It's a pretty simple system and quite different to other types fitted with a trim-tab type set-up and not much can go wrong with it.

 

 

[poteroo]

We operate a 160C for training and have picked this up by adding: trim - SET to the pre-runway entry checks: TXP to ALT, strobe-ON, flaps - SET, trim - SET

 

We avoid TOUCH & Go's because there's no time to reset the trim. We only do STOP & GO's, which allows for a pre-takeoff (short) check of: flaps - SET, trim - SET, brakes - OFF, pump - ON, H&H - SECURE.

 

 

[Guest Macnoz]

Brentc

 

We will have to agree to disagree on this. It certainly doesn’t adjust the neutral position. I tried it today and far from having to pull back the stick to take off the poor little thing attempts to take off in the new “neutral” position. I had to push the stick forward beyond the resting position to continue a safe climb and prevent stall

 

John

 

 

[Yenn]

The trim position controls where the stick settles without any input from the pilot, therefore full up trim is going to require forward pressure to prevent early rotation. This is of course a simplified explanation, but describes the effect of most types of trim.

 

For safety take off with the trim set for take off, not full aft or forward.

 

Some military such as the Westland Lysander were unflyable without correct trim and the trim had to be altered as speed picked up on take off and also during the landing.

 

 

[motzartmerv]

I have noticed this to.. But i always have a little back pressure on the takeoff roll to keep the nosewheel light and easier to steer, but yes, i always seem to be pushing foward to get the 70 kts up, so once im up i retrim and then trim again after the flaps are away..

 

cheers

 

 

[Guest brentc]

Yes Ian, you are correct and your words better describe what I meant. The trim determines where the stick settles. Actual stick position for takeoff should be used as the reference so that a student and or pilot knows whether the trim is set correctly or not. If a student can't take off on a touch and go because the trim is set too agressively I would suggest that it should be adjusted to a lesser extent. Some resistance on the controls is often healthy and should avoid any violent pitching up when power is applied.

 

 

[Whack777]

A couple of interesting things have come out of this thread for me.

 

Firstly, are there any ultralight aircraft that cannot be controlled fully if the trim is not set properly? My guess is probably not... but I would like to know.

 

So if this is the case.... the next thing is to ignore pressure on the stick (in either direction) and fly an attitude/airspeed. ie if the nose starts to pitch up on takeoff before your takeoff speed push forward and keep it in the right place until the airspeed is right and then climb... only then adjusting the trim to take pressure off. Conversly if the nose does not rise or feels heavy at an airspeed where it should start to feel light apply backpressure and pull it up to the right attitude.... adjust as required to get right airspeed/attitude and then trim later.

 

Intersested that Poteroo is not doing touch and goes... as I think a touch and go would require a similar input to a go round. ie proably forward pressure on the stick as power is applied. So I'm suggesting... get the attitude/airspeed to whatever is required for what you want to do and then trim out any pressure later.

 

Obviously, if there is an aircraft that "can't" be flown with incorrect trim set then this would make setting trim absolutely critical of course. I'm talking ultralights here!!!

 

Does this sound reasonable?... cause if it's not, I'd like to know why and have a think about it.

 

Regards

 

 

[Guest Macnoz]

I have had 3 different instructors in different schools in Jab 160 / 160C

 

During touch and goes each has “insisted” on either resetting the trim or bring up the (electric) flaps to takeoff during the roll while I did the remainder. This was briefed to me by them before the TnG so it wasn’t my inability to multi task

 

I can see why with adequate runway and understanding circuiteers, (I know its not a word but it should be) instructors would have stop and goes.

 

I have also noticed a high wing Tecnam in our local aerodrome having a protracted delay on ground during touch and goes and asking around the traps about it the purported ‘excuse” from the CFI is that it takes a very long time for the electric flaps on those to come back to t/o position

 

 

[Guest ROM]

OK! You have never been trained by your instructors to do "touch and go's" all by your lonesome!

 

So what do you do and how do you handle things when you go into a bush strip or even some airstrips and a mob of kangaroos bound out in front of you or cattle or sheep, startled by your aircraft, run out of the scrub.

 

Add to the list, an unsuspecting vechile driver appearing on the strip or a bloody great outback willy willy appearing out of nowhere down the middle of the strip.

 

Add to this the unexpected, out of the blue, non radio using local aircraft just banging around the area in some local barely used airstrips.

 

You just have to get to hell out of there and fast but your instructors have never trained you to do the deed in cold blood and without all sorts of provisos.

 

Seems to me to be somewhat of a recipe for a potentially serious accident waiting to happen.

 

 

[facthunter]

Coping with.

 

Good point ROM. These situations should be coped with competently, as an abnormal rather than an emergency procedure. I don't believe that going around with landing flap extended is acceptable as a principle. A minumum check of the essential items is required to ensure that the aircraft is configured to perform and be controllable. The point made on this thread about putting the aircraft where it should be (attitude wise) regardless of how it feels, (never let the aeroplane fly you) is basic, but why would you commence take-off with the trim set away from where it is optimum if you can avoid it? nev....

 

 

[Guest ROM]

Agreed, Facthunter. Correct checks and establishing the correct sequence of checks should always be carried out.

 

I learn't this when flying a new type of glider for the first time a long time ago.

 

Did the usual quick instrument check but the ASI was in a different position to the usual and also looked different so I found myself frantically scrutinizing the panel for the ASI as we towed out at low level.

 

A tow rope break in this situation with a completely unknown aircraft with a subtle and unknown feel, responses and attitude means that you are totally reliant on the ASI to establish an adequate and correct airspeed as you head down for an emergency landing.

 

One of the factors that makes me rather nervous about a lot of training by a lot of instructors is the manner in which trainee pilots are taught the basics of flying as they apply to a specific type of aircraft with it's own specific handling characteristics rather than being taught the real basics of flying which allows one to fly all aircraft types regardless of their particular handling quirks.

 

A couple of posts above are very good examples of very specific aircraft handling characteristics being apparently taught as basic flying skills.

 

Those same ingrained flying and handling traits used in another type of aircraft sometime in the future of the pilot may in an emergency or high pressure situation, prove to be a total disaster.

 

Many years ago the french did a survey on the flying characteristics of their fighter pilots.

 

From this survey they could identify who the pilot's instructors were in the pilot's first eight hours of instruction.

 

The way your basic flying skills are taught in the first eight hours of your flying training will stay with you for the rest of your life.

 

Psychologically and skill wise, it is almost impossible for a pupil to actually question his / her instructor as to the long term suitability and safety of the techniques that an instructor is using so it is up to the instructor to frequently question the content and manner of their own instruction techniques.

 

 

[Guest brentc]

It is very normal in the early stages of instruction (solo time) for the student to be told to not conduct a touch and go, but rather a full stop, backtrack and take-off. Usually later on in training the student gets to do touch-and-go's on his own if required, although some would argue that there is little value in touch and go's when the pilot / student is more advanced. In the real world touch and go's are very rare outside a training environment.

 

 

[Yenn]

There could come a time when a touch and go is essential outside of training. What happens when roos dash across in front of you. In my opinion, full power and initiate a climb, then retract flap very carefully.

 

I know you can climb with full flap with most types, but the attitude is going to be very different from normal, drag is going to be horrendous, but you may just avoid a crash.

 

Training allows you to prepare for the worst, safely and with an instructor watching over you. Of course if you are able to slip the plane in you don't need flaps and the instant you ventre the controls you are in a clean configuration.

 

If the POH allows slipping, give it a go. You will be a better pilot and in my opinion safer.

 

 

[facthunter]

More.

 

There are two separate issues here, trim (pitch) and configuration (flaps incorrectly set ie, full flap for take- off, go round or touch and go).

 

...... The trim should be able to be overpowered on the aircraft that we fly ,but it adds to the difficulty of flying the aircraft precisely. It is bad practice as on some aircraft it cannot be overpowered, so getting it right should be given some attention.

 

....... Flaps are now commonplace on a lot of RAAus types, and full flap would significantly deteriorate some aircrafts ability to climb (due to drag, particularly the CT) As well the final flap selection often causes the pich trim to change markedly. It will also cause the aircraft to wheelbarrow down the runway (weight on nosewheel) if the aircraft is held on the ground excessively during a touch and go. HOWEVER if you NEED to go-around then it should be commenced even with the incorrect flap, and the flap reset when it is safe to do so. In an extreme case the flap should be "milked up" to the correct position while still in ground effect allowing the speed to build up at the same time. Touch and go's are probably used to give the student more actual landings in a given time, than would be the case otherwise. Operationally the go-around is probably more common. Nev...