DHC-3 Otter

[Krazycolin]

so, if you use differential braking (after having moved a bit) the tail wheel still won't rotate?

[Taguilo]

Tailwheel switch positions;

Down - Castor (Free) Mode - Green and Yellow lights OFF

Is the default mode. Reacts to pedal commands above 5-6 knots; at lower speeds rudder has not enough authority to overcome forward inertial, so tw will not rotate as expected (also differential brakes have little or none effect on steering)
With enough forward speed, tw can rotate freely after pedal commands, and 360 turns can be done using differential braking, as already explained in another messeage.

Middle - TailLock Mode - Green light ON

In this mode tailwheel remains centered despite pedal inputs. Only effective for straight rolling or gentle turns. Differential braking has little effect on steering/turning. Too much sideslip unlocks the mechanism and wheel go into free rotation, coming back to locked when slip ends.

Up - Ground Steering - Yellow light ON

Tailwheel rotates in response to pedal input, even with the aircraft stopped. At very slow speeds brings better control for tight turns, as not depending on rudder action. Great control with strong crosswinds. Differential braking has little effect in turns, more a stopping action.

System works as expected. Hope that this issue is clear enough now.

Tomas

[CAPFlyer]

so, if you use differential braking (after having moved a bit) the tail wheel still won't rotate?

No. It will simply stop in a straight line. I can get a little bit of steering like Taguilo can when above 5 knots or so using the rudder with it, but that should have no effect on a free castoring tailwheel. I should be able to steer solely with differential braking pretty much from a stop (excepting the known FSX limitations on braking dynamics and ground friction that makes turning from a standing stop nearly impossible unlike real life). As much problem as the default FSX has, the default free castoring tailwheel operation in the sim is actually pretty spot on (even if the animation isn't), so I gauge reaction of addons from it. I don't try to hold you guys to A2A levels of tailwheel operation.

[Taguilo]

so, if you use differential braking (after having moved a bit) the tail wheel still won't rotate?

No. It will simply stop in a straight line. I can get a little bit of steering like Taguilo can when above 5 knots or so using the rudder with it, but that should have no effect on a free castoring tailwheel. I should be able to steer solely with differential braking pretty much from a stop (excepting the known FSX limitations on braking dynamics and ground friction that makes turning from a standing stop nearly impossible unlike real life). As much problem as the default FSX has, the default free castoring tailwheel operation in the sim is actually pretty spot on (even if the animation isn't), so I gauge reaction of addons from it. I don't try to hold you guys to A2A levels of tailwheel operation.

Please read what Fliger747 wrote, He IS a REAL Otter pilot, has done the FDE and I bet knows something about this issue.

There is not an A2A Otter so it makes no sense to compare.

I'm sure with some practice you will end mastering Otter's different steering modes

Tomas

[Fliger747]

It is always a good idea for us to go back and test as sometimes with such a complex sim aircraft things change!

As far as my test in P3d V4 goes it works "OK". As with the original using the T/W steering is a little bit of a PITA, so I guess we can chalk that up to "realism". The Lock position, used for takeoff and landing works fine, the steering position seems to work OK as designed and the castoring position does castor after a bit of a nudge. The real plane tends to be like this, somewhat hard to break the T/W into the castor and about impossible without a little speed. In a taildragger the speed helps differential braking a lot as the CG is behind the main gear and with speed the divergent forces are multiplied. The same effect which causes a ground loop.

It might be that differential braking is slightly less effective than in the actual aircraft, but not by a lot. A more realistic effect will be obtained with pedals as opposed to a twist stick.

An appreciation of how to fly this unusual aircraft would be a lot easier if you had an experienced check pilot biting his nails in the right seat.

[CAPFlyer]

Please read what Fliger747 wrote, He IS a REAL Otter pilot, has done the FDE and I bet knows something about this issue.

There is not an A2A Otter so it makes no sense to compare.

I'm sure with some practice you will end mastering Otter's different steering modes

Tomas

Or maybe you actually read my post that you quoted in full instead of trying to be a dick about it?

1) I specifically stated I'm not comparing it against A2A (who the guys at MilViz and other places are aware I do a lot of BETA testing and other work for), so drop that BS.

2) I said the GAUGE was acting weird and not being consistent in operation. I didn't say that the FDE handling was wrong. Fliger747 didn't write the gauge code and it's not unusual for gauges, even when coded correctly, to act weird after compilation because of the way FSX handles some of this stuff. We've had several times in A2A test where we went through 3 or 4 test builds and a gauge worked fine only for a change to be made elsewhere and then when recompiled, the gauge that had been working fine now had an issue because of something happening in the compile.

[Taguilo]

I specifically stated I'm not comparing it against A2A (who the guys at MilViz and other places are aware I do a lot of BETA testing and other work for), so drop that BS.

Oh yes you actually did. In your comment "I don't try to hold you guys to A2A levels of tailwheel operation" you are in other words implying that Otter tw operation is not, or might not be, at same level with A2A aircraft, which to me is quite inappropriate considering that, as per your comments (see below), you don't really know how a real Otter must be steered in ground operations.

I said the GAUGE was acting weird and not being consistent in operation.

Doesn't seem so. After I described TW modes and confirmed system was working ok, you commented "I can get a little bit of steering like Taguilo can when above 5 knots or so using the rudder with it, but that should have no effect on a free castoring tailwheel. I should be able to steer solely with differential braking pretty much from a stop" which does not apply to the Otter, as confirmed by Tom (Fliger747).

So, I can accept that you might not like how the Otter performs on the ground, but that is completely different to insist on a wrong (gauge or whatever) behavior, much after the explanations given.

Case closed.

Tomas

[Fliger747]

At various times during the development various scenarios were tried with the tailwheel initially using the stock simulator fry castoring and steerable functions. Note that even with a fully castoring tailwheel it takes a bit of motion with differential braking to get good turns. This is due to the weight and geometry of the aircraft which is fairly long, has the mains well in front of the CG and proportionally a fairly narrow track. There are good reasons that DH installed the complexity and weight of a steerable tailwheel in this aircraft.

A wider tracked and more short coupled aircraft would respond much more happily to differential braked turns. P47 comes to mind...

Even the smaller Beaver with it's rather wimpy cable and spring tailwheel steering was reluctant to turn with differential braking pulling out of a parking spot.

[CAPFlyer]

1) MilViz's aircraft are (by their own admission) and by technical point, not as in depth as A2A's. This is not a negative necessarily. MilViz does not mess with the kind of back-end stuff that A2A does via AccuFeel and Accusim and in many ways that's a good thing. I am one who doesn't always want to have 100% study-sim level complexity for me to fly. I like to occasionally get in something simple that I can abuse somewhat and not get major failures. That's why I continue to buy MilViz.

2) I'm sorry if I didn't explain what I'm getting well enough. Having watched real world ground handling of the DHC-3, they are able to get the tailwheel castoring once they get just a knot or two of forward speed (slow walk). With the MilViz aircraft, I can't get it to steer AT ALL with differential braking unless I cycle the switch and even then occasionally it will "reset" after I stop and lock up the tailwheel where the only way I can get steering of any type is with the rudder and then it's still limited (it never "breaks free") until I hit the brakes. When it's still "locked" and I hit one brake it just goes straight ahead until it stops again. Again, I shouldn't have to deflect the rudder once I get rolling to get it to turn with the switch in the "OFF" position, I should be able to just use differential braking & this is confirmed by the handling notes for the airplane. It's not doing that.

[Taguilo]

MilViz's aircraft are (by their own admission) and by technical point, not as in depth as A2A's.

Well, it depends on which aircraft. From a strictly technical point, our Otter includes all the systems present in the real aircraft that can be simulated, and the FDE has been done by a real pilot, with different reactions depending on model (wheel,float,skis). Sounds are quite realistic as well. Even some fancy visual effects have been added to the engine management, which might not be strictly real but give better sensations to a pilot flying in front of a monitor. Similar to what A2A does with Accufeel/Accusim - great improvements indeed-. I can't say then that our Otter is below A2A system's level as there is no A2A Otter to compare with.

I can't get it to steer AT ALL with differential braking unless I cycle the switch and even then occasionally it will "reset" after I stop and lock up the tailwheel where the only way I can get steering of any type is with the rudder and then it's still limited (it never "breaks free") until I hit the brakes. When it's still "locked" and I hit one brake it just goes straight ahead until it stops again. Again, I shouldn't have to deflect the rudder once I get rolling to get it to turn with the switch in the "OFF" position, I should be able to just use differential braking & this is confirmed by the handling notes for the airplane. It's not doing that.

Ok, lets clarify things:

-At very low speeds (4-6 knots) tw won't castor free. I guess this is particular for the Otter and I believe is one of the reasons to include a steering motor option. Confirmed by Tom. Working ok.

-In same conditions, differential brakes can only produce ample turns, in most cases the aircraft will come to a stop if constantly braked. This has been confirmed also by Tom, so working ok.

-Above very low speeds, tw castors free, and it is possible to make turns up to 360, as expected. Current configuration allows free castoring and turns with differential brakes AND rudder input; without rudder turns are limited in amplitude, and 360s are very difficult. It is intended to work that way . However, after your observation I asked Tom if it is possible for the real Otter to make a 360 with differential brakes only, without rudder input, at low speeds (6-8 knots). If he says it is, I can easily change the code for that. So let's wait for his comments.

Tomas

[CAPFlyer]

Tomas, with the "in depth" I meant more the consequences side that Accusim puts in. The plane doesn't "wear" and change like the A2A planes do, which again, I don't find a negative. There's times when I turn Accusim off myself because I just want to fly, but that's not what makes their planes "theirs", so I try to fly with it on as much as possible. But I like the planes that I can just get in and fly and not worry about random failures too.

Thank you for clarifying. From the videos I saw, maybe they're toggling the power steering and I'm not seeing it, but it looked like they were at walking speed and using only braking to turn, which was what I was comparing to.

[stephan.cote.1]

Okay, I'm about to do a very riscky thing here.. that is to ressussitate a old thread...

I just wanted to share what I've heard from old Propair and Air Fectaux pilots about the reason behind the tw motor... One have to stand beside a real otter to appreciate the lenght of the cabin and the sheer size of the tail on that bird.. sure its not a Dash 8 but again, this is 1950 technologies where Rudder, Elevator and ailerons are actuated with cables!

Dehavilland Canada had to install a tailweel motor for two main reasons:
1- a heavy loaded Otter has most of its mass centered between the main and the tail wheel, so initiating a turn even with differential breaking was not easy... yes you have a huge rudder to work with but remember its 45 feet behind the prop....
2-because of how hard the it was to fight the tendacy of the Otter to weathercock in the wind so turning a Otter on the ground with some wind requires quite some work...

To put things in perspective, when operating on float, you have no motorized tailwheel right? My dad, who was about 160lbs when he was a pilot, use to joke that the only thing holding him on his seat when pushing the rudder pedals during water ops was the seatbelt....

Cheers,
Steph