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Jens DC 4. Version with Sperry. Elevator trim query please


Cas141

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Hello.

I'm flying the Sperry version , not the one with the red/brown autopilot system .

I know that once the Sperry is activated( green light on ), that the elevator trim is controlled by the pitch control of the Sperry.

However, my problem is , at the start of the flight, I need to ensure the elevator is trimmed central. I have found climbing to 9000 and above very difficult in that I run out of puff, and stall

I fly with automixture. I know about MP and RPM, and I adjust soon after take off to Mp 36 and RPM 2250. I set the trim at 5-6 degrees.

( perhaps you can advise on cowl flap settings?)

Anyway, I took a look at outside view and found that after hitting the "alt hold" and getting so called level flight, that the attack angle of the plane was clearly too high. It wasn't "level"

This suggested that before flight I had too much up trim in when it should have been neutral trim.

 

Ominously, the big trim wheel in the plane doesn't seem to respond to inputs ( keyboard or mouse). I've tried using the plus/minus of the knob below

the trim dial. That shifts the line representing the plane up to level, but it doesn't seem to affect the flight characteristics.

 

Anyone able to assist please. It's pleasing to use the Sperry , but this trim issue is spoiling it.

 

Thanks

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Hello.

I'm flying the Sperry version , not the one with the red/brown autopilot system .

I know that once the Sperry is activated( green light on ), that the elevator trim is controlled by the pitch control of the Sperry.

However, my problem is , at the start of the flight, I need to ensure the elevator is trimmed central. I have found climbing to 9000 and above very difficult in that I run out of puff, and stall

I fly with automixture. I know about MP and RPM, and I adjust soon after take off to Mp 36 and RPM 2250. I set the trim at 5-6 degrees.

( perhaps you can advise on cowl flap settings?)

Anyway, I took a look at outside view and found that after hitting the "alt hold" and getting so called level flight, that the attack angle of the plane was clearly too high. It wasn't "level"

This suggested that before flight I had too much up trim in when it should have been neutral trim.

 

Ominously, the big trim wheel in the plane doesn't seem to respond to inputs ( keyboard or mouse). I've tried using the plus/minus of the knob below

the trim dial. That shifts the line representing the plane up to level, but it doesn't seem to affect the flight characteristics.

 

Anyone able to assist please. It's pleasing to use the Sperry , but this trim issue is spoiling it.

 

Thanks

 

You seem to have a fundamental misunderstanding about Trim and how it works.

One adjusts trim to achieve-and hold- the desired flight attitude, not for any other reason.

 

The goal is ALWAYS to adjust it for the flight mode and power level you're in, not some arbitrary `neutral` position.

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At just after takeoff, your prop RPM seems a little low. It should be set just into the green zone (around 2500). Reset to 2200 after reaching cruise. I would normally set cowl flaps to nearly full open until reaching cruise altitude and then close them.

 

Most aircraft, default and 3rd party, tend to fly with a slight upward angle of the dangle.

Still thinking about a new flightsim only computer!  ✈️

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The correct climb rate would normally be around 39"/2300 RPM, reducing the climb rate as power tails off. Cruise between 29" and 36" (depending on your desperation to reach your destination and whether your employers can afford the fuel!) at 2050 RPM.

 

I doubt Sperries were used much during climb, just engaged at cruise and then adjusted to maintain it. The Microsoft implementation of a Sperry isn't very realistic, the MAAM DC-3 has a better one.

 

Cowl flaps fully open on ground, mid-position during take-off, climb and landing, closed at cruise and descent.

 

Make sure you retract the landing lights as soon as possible after take-off as they cause drag too. In those days you didn't keep your lights on for long after take-off for a very good reason!.

 

John

http://www.adventure-unlimited.org

 

My co-pilot's name is Sid and he's a star!

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The correct climb rate would normally be around 39"/2300 RPM, reducing the climb rate as power tails off. Cruise between 29" and 36" (depending on your desperation to reach your destination and whether your employers can afford the fuel!) at 2050 RPM.

 

I doubt Sperries were used much during climb, just engaged at cruise and then adjusted to maintain it. The Microsoft implementation of a Sperry isn't very realistic, the MAAM DC-3 has a better one.

 

Cowl flaps fully open on ground, mid-position during take-off, climb and landing, closed at cruise and descent.

 

Make sure you retract the landing lights as soon as possible after take-off as they cause drag too. In those days you didn't keep your lights on for long after take-off for a very good reason!.

 

John

 

Thank you John, and thank you all.

Interesting about not using Sperry. during climb? So no auto pilot functions during climb, just pure manual control?

Reference trim. As far as I can see there is a trim wheel, and other buttons that seem to adjust trim. But using them in this plane is not done by mouse over the trim wheel( as in other planes)

So what trim is there of the plane before take off. Seems to me that one uses those trim adjustments to ascertain neutral trim, then, for take off, dial in a little up trim..

This is what happens in David Maltbys Comet and BAC 1-11. And in these, when cruising, level flight with no exaggeration of angle of attack is achieved.

I have a feeling , with this DC 4, that when the flight is loaded, the plane is not at neutral trim.

The trim dial has a couple if adjustment rotating buttons, and a "cage" button. What does that do exactly , please?

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