Twotter Issue.

[Manny 41]

OK..Could someone confirm if this is just me or is this how the Twotter reacts to control input.

1. Set winds to 0. MAke sure..the weather does not interfere.

2. Full RPM settings (to keep that constant) and Torque pressure at 30.

3. Fly straight and level and trim so that its straight and level when your Yoke is centered, its flying straight and level. At this point the IAS should be around 130kts.

4. Now, Hold the yoke in the same position and do not make any movements to the yok, while increasing the throttle...to 50.

Now, why is the aircraft nose diving? and descending at 1000-1500fpm?

When you increase the throttle..watch the attitude indicator, its pitching down even though, you have not changed the pitch via the yoke. I would think the it would have pitched up instead of pitching down.

Its basically expecting me to pullback and trim instead of pushing and trim.

When you reduce the throttle from straight and level, the opposite is happening, expecting me to push and trim. I find that strange.

Manny

:shock:

[Chaders 97]

Hi Manny,

I'll check this out later but if you think about where the engines are compared to the centre of Gravity (Mounted on the High Wing)any sharp increase in power would actualy cause a pitch down. This is the oposite to airliners with thier low slung engines where care must be taken especialy during a go around where the pitch up effect can catch you out.

[Aerosoft Team [Inactive Account] 51558]

OK..Could someone confirm if this is just me or is this how the Twotter reacts to control input.

1. Set winds to 0. MAke sure..the weather does not interfere.

2. Full RPM settings (to keep that constant) and Torque pressure at 30.

3. Fly straight and level and trim so that its straight and level when your Yoke is centered, its flying straight and level. At this point the IAS should be around 130kts.

4. Now, Hold the yoke in the same position and do not make any movements to the yok, while increasing the throttle...to 50.

Now, why is the aircraft nose diving? and descending at 1000-1500fpm?

When you increase the throttle..watch the attitude indicator, its pitching down even though, you have not changed the pitch via the yoke. I would think the it would have pitched up instead of pitching down.

Manny

:shock:

Basically because the thrust vector is ABOVE the CoG. If somebody pushes you on your but you will move forwards, if somebody does the same on your head you would lean forwards. On most aircraft the engines are close to the CoG and you would not see this effect. You see exactly the same effect in the default Goose, also an aircraft with engines above the CoG. See the image.

However... although the parameters are all correct there are some indications the effect is not well calculated by FSX, we are looking into that.

[Aerosoft Team [Inactive Account] 51558]

Hi Manny,

I'll check this out later but if you think about where the engines are compared to the centre of Gravity (Mounted on the High Wing)any sharp increase in power would actualy cause a pitch down. This is the oposite to airliners with thier low slung engines where care must be taken especialy during a go around where the pitch up effect can catch you out.

Indeed indeed... I have been in an airbus cockpit (sim, not real) where I was flying at very slow speed. when I kicked open the throttle the trim was working very hard to keep the nose down. Really amazed me.

[Chaders 97]

Indeed indeed... I have been in an airbus cockpit (sim, not real) where I was flying at very slow speed. when I kicked open the throttle the trim was working very hard to keep the nose down. Really amazed me.

Hi Mathjis,

It's very easy to get into stick shaker territory if you hit the TOGA switch and are not ready for the pitch up.

[Manny 41]

Basically because the thrust vector is ABOVE the CoG. If somebody pushes you on your but you will move forwards, if somebody does the same on your head you would lean forwards. On most aircraft the engines are close to the CoG and you would not see this effect. You see exactly the same effect in the default Goose, also an aircraft with engines above the CoG. See the image.

However... although the parameters are all correct there are some indications the effect is not well calculated by FSX, we are looking into that.

K That diagram helps.

That is good to know indeed!

Interesting. Learn something new everyday.

Thank you for that detailed explanation.

Manny

BTW.. would this happen to an ATR too? Any ATR drivers here?

[Aerosoft Team [Inactive Account] 51558]

Manny

BTW.. would this happen to an ATR too? Any ATR drivers here?

In principle yes, but ATR's are much longer and got a lot more weight far from the CoG so the effect will be a lot less.

[Manny 41]

Thanks Mathijs and Richard .

I am glad I asked. Now, every time I increase the throttle and the nose pitches down, I am a happy camper..knowing I am flying a unique and realistic aircraft instead of thinking it has a bad flight model.

It pays to ask without the fear of exhibiting ignorance!

If I had gone up with an instructor on that aircraft for the first time..My reaction would have been the same. I would have turned around and asked the instructor..what the heck is happening. I am used to flying a Piper Seneca.

Manny

[Jan R. Storelvmo 67]

Thanks Mathijs and Richard .

I am glad I asked. Now, every time I increase the throttle and the nose pitches down, I am a happy camper..knowing I am flying a unique and realistic aircraft instead of thinking it has a bad flight model.

It pays to ask without the fear of exhibiting ignorance!

If I had gone up with an instructor on that aircraft for the first time..My reaction would have been the same. I would have turned around and asked the instructor..what the heck is happening. I am used to flying a Piper Seneca.

Manny

I have noticed a strange trim issue. When I fly in straight and level with the Twin Otter and then pull back on the throttle the nose goes straight in the air. Exactly the opposite of what it's supposed to. The trim also acts strange. Besides this, the twin otter is just the best aircraft around.

[Aerosoft Team [Inactive Account] 51558]

I have noticed a strange trim issue. When I fly in straight and level with the Twin Otter and then pull back on the throttle the nose goes straight in the air. Exactly the opposite of what it's supposed to. The trim also acts strange. Besides this, the twin otter is just the best aircraft around.

No, just read the whole thread and you will understand why removing thrust will cause a pitch up. We are now sure that it is too strong, but it should be there.