Do-27 Rudder Trim

[Duckair 1]

I bought myself the Do-27 for Christmas and I'm really enjoying it. The plan is to fly down the west coast from Seattle, through Mexico, and the length of South America to the most southerly airfield I can find. At each successive stop I've tried to maintain the aircraft in keeping with what I believe the the sim designers intended.

From the first the aircraft had a tendency to swing to the left which I expected. At each stop I adjusted the trim a little more and noticed I had less correction to do when flying. Not wanting to over do it I only did a little at a time. Now, I've reached the stage where I've done all the trim I can but I still get a curve to the left.

Is this is as intended (like the real aircraft) or is there a way I can add more trim. Either way I'm happy with the aircraft. It really is great fun.

Kind Regards,

Cliff

[JulianEDFM 0]

This effect comes from the Engine, and it's real. I don't know the english word, but in German it's called "Kreiseleffekt"

[Duckair 1]

Thanks Julian It's just seems a bit strange that it can't be trimmed out completely. In the Beaver you can set it so the aircraft circles either to the left or right. However, that is adjustable from the cockpit while in flight. With the Do-27 you do it before you start up, so it's set for the rest of the flight.

I'd assumed that if you knew the airspeed, altitude, and direction you intended to fly that day you could factor that in during the walk around the aircraft.

Thanks for the info,

Kind Regards,

Cliff

[Snave 466]

(Yawn), READ the Fine Manual... 6.2 if you can't be bothered to look

GROUND ADJUSTABLE rudder trim tab...

[Duckair 1]

(YAWN) Read the first post:

From the first the aircraft had a tendency to swing to the left which I expected. At each stop I adjusted the trim a little more and noticed I had less correction to do when flying. Not wanting to over do it I only did a little at a time. Now, I've reached the stage where I've done all the trim I can but I still get a curve to the left.

Thanks anyway Simon. Nice to see you haven't changed after all these years. :roll:

Kind Regards,

Cliff

[Snave 466]

Nope, consistent as ever. The solution is whether you use that ground adjustability to set up the aircraft for cruise, take-off or some other phase of flight. Just like a real one. If you set it to take out most of the effect at take-off then obviously it will be at the cost of some foot pressure at steady-state, lower-powered cruise, but the option exists according to the pilots wishes: If all you are doing is flying circuits and bumps, then it makes sense to reduce the effort required in climbout, as you spend almost no time at cruise.

If you're doing a long cross-country, then you'd set it for feet-off at medium power and cruise speeds. What you cannot do is have it set up for both, at the same time. That's why it's only ground adjustable.

[Duckair 1]

My point is I've now reached the limit of what the configuration allows. Even with the rudder fully trimmed over I still get a turn, albeit slight, to the left. I was wondering if the simulator aircraft could be trimed more to make it fly straight at a specific cruise speed. From what I've seen it can't. Admittedly, you would have to cope with it on the way up and down but for the majority of the flight you'd be flying without having to apply some extra rudder pedal.

If this steady state (no pedal and straight flight) is achievable then can anyone tell me the cruise speed max trim is appropriate too?

[Snave 466]

Then that indicates more than a trim problem - possibly a lop-sided loadout, or fuel imbalance

[ChrisB 11]

Take your left foot off the rudder perhaps?

But Simon is right - unbalanced loadout will "lean" you - are you regularly changing fuel tanks (what was it now... every ten minutes, if I remember correctly for "normal" ppl types...) Remember too - you are sitting left of the CL - got any (pretty?) ballast in the right seat? Check the pax weight - if you are at 100 Kilos and pax at 50... well, you're going to lean eventually.

The DO27 is really a nice wee plane... but she was around long before many of us here, and she's not used to new-fangled pilots. I did a "timed arrival" rally in the Do27 - three seconds off my planned touchdown time. Trim and everything was perfect and despite real weather and a wind from the right quarter, she trimmed up very nicely over an hour and a quarter.

But yes, she does need a lot of practice - both real world and sim.

[Snave 466]

As we don't know whether we're talking FS9 or FSX here, nor the controllers being used (usual half-information supplied, hence - yawwwwwn), then it is really a moot point to discuss the inner workings of the aircraft when the problem is clearly operator error, or hardware problem.

However, FS9 exaggerates the off-centre effects of loadouts to a massively disproportionate extent. For this reason the station loads in the default aircraft .cfg's are all balanced left:right and should be left that way. Fuel loadouts are also problematic, and a lot can depend on HOW the aircraft was loaded - if an aircraft was loaded prior to the Dornier had a left/right fuel tank selector and not a `both` option, then it is entirely possible that the aircraft is developing a list based on lopsided fuel usage - operator error as changing tanks is a standard procedure (again, no user information provided on this so we can neither identify it, nor eliminate it as a cause: Mind readers, step forward please).

Next, in the half-completeness of this alleged troubleshoot we have not been given the weather state. This can also affect the high winged Dornier which of course had a parasol-type wing, (in terms of relative location to fuselage) and a low wing-loading. This might also make it more susceptible to side or angular winds, but then of course Chris and I wuold have noticed it too. And we haven't.

Then we can look to the power and prop settings. Failing to abide by the manual can also cause the `problem` described here. Again, nothing more than operator error, but we are not given that information either...

So the final option is a problem with controller calibration. But as we don't have even the slightest clue as to whether we are talking to a mouse-flyer or home cockpit flyer, I really can't be bothered to offer help on that score.

Look people, you want help? GIVE THE INFORMATION, or don't waste our time, and yours.

[Duckair 1]

Thanks ChrisB for the advice. I've tried the Do-27 in real weather and in default calm conditions. One for the first things I experimented with was prevailing wind making an icreased or reduced effect. As far as I can tell the rate of turn is constant.

Accroding to the fuel gauges they are draining at the same rate so they are on 'both'. On start you need the port tank seleced because of the fuel return but having both selected doesn't cause a problem. I've got the passenger loaded, and set our weights to the same - I put hers up instead of mine down, she didn't like that. All things considered we should be in balance.

I do wish I had rudder pedals! Unfortunately I'm restricted to a twist stick :cry: However, I do calibrate the stick when I load FSX because I've had problems with FS9 and sticks in the past. Another one of my experiments was to see if I'm inducing the turn. To test that I just level the wings and take my hands off. The left swing soon sets in. I've even tried to set in some slight right turn to see of that will maintain but that soon goes back to wings level and continues off to the left.

Manifold pressure is between .6 and .9. Prop speed is 3400 on take off and once I've got a rate of climb after flaps are up that is reduced to 3000. As far as I can see I'm flying it by the numbers.

However, you have given me an idea. Why not start off with the port tank slightly lighter than the right? Say, 5 or 7 kilo?

Simon, not only do you lack social skills but have also failed to grasp the concept of a 'conversation'. It's where two humans, or more, discuss a topic in a turn and turn again manner each developing the others knowledge as they go along. It's been around for a few years now and is quite popular. I seem to have given others a glimmer of what I'm driving at but you're too busy trying to demonstrate your superiority to see that. If I'd have told you everything you wanted to know, and I'm not a mind reader either, you would have complained about the manner in which it was presented or the quantity.

There must be an awful lot of room in your play pen after you've thrown all the toys out

Kind Regards to all, even you Simon :roll:

Cliff

[Snave 466]

Refer back to your insipid initial post. It was a technical support question, pure and simple. If you want conversation then engage in discourse, NOT direct questioning:-

Is this is as intended (like the real aircraft) or is there a way I can add more trim.

Therefore in order to receive technical help, try THINKING about the information you might need to impart in order to receive the desired answer. I see no sign of that thinking, cannot engage you in conversation, much less provide technical help. A fine example: We STILL have not been given the secret of which sim you are actually talking about - in your latest reply you mention both, but specify neither.

This is not about superiority, this is about common sense. You have demonstrated precious little of it so far, yet in EVERY reply I have given I have gone out of my way to supply further clues as to what ails you, but still you neither pick up on those, or ascribe them to anothers question. Which in each case he did not ask, I did. Is that your idea of a conversation then..? How ignorant!

By the way, you are in the WRONG forum for tech support for this product. And as for `superiority`, even without the revelation of precisely which sim we are talking about, I now know what the problem is, and funnily enough, the solution...

...and I wish you good luck with finding it, because I rather doubt you'll find it from the information supplied so far, unless someone else here also has the prescience to read between the lines!

[Duckair 1]

That is so funny Simon.

I'll not deny you have been helpful, and for this I'm very grateful. Thank You. . ChrisB and you given me things to think about, and I believe I'm close to a solution. I'm not sure if this is applicable to 'real world' aviation or just the sim. I've reduced the fuel in the left tank and have got a very promising reduction in the left turn in all aspects of the flight.

Thank you very much for the help everyone

Kind Regards,

Cliff

[ChrisB 11]

We could go into business Simon...

"Good cop, bad cop" :lol: You say what other folk sometimes only think... but I understand between your lines too.

[alehead 126]

Correct me please if I am wrong, but I do believe there is no "both" setting on the Do-27, at least in the FS9 version... so, you have to switch tanks regularly to keep the plane in trim...

There is also quite a bit of drift associated with the engine torque... You need to set the trim on the ground in accordance with the type of flying you intend to be doing...

Love the Do...

Andrew

[Duckair 1]

Hi alehead,

You're probably right. I'm in the FSX model and that gives three positions to the tank selector lever.

For those who are interested the Do-27 trims up very nicely after a few minutes of running on left tank to counter the tendency to turn to the left. I've started to switch to the left tank once a stable rate of climb is established and then reverting back to both just before levelling out at my proposed flight altitude. I was flying it at the weekend and could sit back and take in all the views for 10 minutes 'hands off' and the Do had only deviated by 3 degrees

If I were just doing circuits and landings I'd start off with the left tank 20 pounds less than the right. That will take most of the turn out. I'm still refining the settings but 20 pounds was my start figure and it really made a huge difference, that was with the trim at full right deflection. I'm still trying to decide on the benefits of having less deflection and less fuel in the left tank. I get less range but less stress on the rudder and tab. For all I know in a few weeks I'll get told that I need a new rudder because I've overstressed the old one :shock:

This is one aircraft which just gets better and better with experience.