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Throttle and pitch response

Printed From: Just Flight Forum
Category: Just Flight Products
Forum Name: C152
Forum Description: Discussion area for C152
URL: http://forum.justflight.com/forum_posts.asp?TID=32285
Printed Date: 21 Aug 2018 at 11:30am


Topic: Throttle and pitch response
Posted By: m3duzas
Subject: Throttle and pitch response
Date Posted: 24 Apr 2018 at 12:21pm
First of all I installed file *_104 so this is version I'm referring to.

Ok, there are lots of things wrong with flight model of this plane especially flaps work, but can You please do something with pitch response to throttle? This one is killing fun to fly this plane on FSX.

I've flown so far 4 different Cessnas with my PPLA and believe me when You give power, real plane gives response to that.....and response is immediate and strong. Nose is going up or going down, simple. Especially while landing it is crucial. Flaps model to land of this plane is NOT good and if any real world pilot is claiming differently then I don't know what to say. But even though it is wrong it can be at least compensated by throttle work........which now is also wrong.

I beg do something with the response to throttle increment/decrement defectiveness

Thanks



Replies:
Posted By: Delta558
Date Posted: 24 Apr 2018 at 2:06pm
For the most recent release, I worked with multiple C152 pilots including at least one instructor. The flaps were the main area we looked at, they went through multiple revisions before we ended up with the current setting which was agreed on by all as being as close to realistic as we're likely to get (both in terms of pitch reaction and drag). Indeed, the reaction of one was that it perfectly matched the experience he has with his club's 152.

With regard to the throttle response, there is no setting within the fde for pitching motion specifically caused by thrust. We are reliant on the sim to calculate that movement. For the initial release (with the engine correctly situated) it gave a pitch down motion with power added before gradually rising. To mitigate this, I have moved the engine's position to below where it should be by approximately half a foot and this has given a slight nose-up movement with thrust increase. However, if the position is taken further away from its correct location it starts to affect many other areas of the flight model and that is not acceptable.

Interestingly, the TB10 and TB20 have a much better pitching response to throttle with the same basics and the engine in the correct place - I think it is possibly down to how the sim deals with high wing v low wing.

Cheers,
Paul.


Posted By: stephane130281
Date Posted: 27 May 2018 at 7:16pm
Hi Paul,

I can only echo the initial comments.
I ve hundred of hours on C152 and because of center of thrust below CG, adding power strongly affect the pitch of the plane at low speed: It is an immediate pitch up or vertical speed increase.

Thus during landing, the throttle control the vertical speed and the yoke control the speed.
Far away from what we observe in the sim.
I don t know to whom you re refering to but all C152 pilots will tell you that adding flaps has also a strong pitch up moment.
On downwind, I reduce the power down to 1500 RPM to bleed the airspeed when in the white arc I put 10° of flaps resulting in a pitch up moment and one has to really push hard on the yoke to keep it straight then I add power to 2000 RPM to maintain 80 kts.
I ve also posted a long list on this forum.
But I strongly disagree with you saying that the flaps behavior is as it should be.

Above all,don t make me say I don t like it...actually I love it and happy of the purchase . Just few corrections would make it a good sim trainer.

Regards
Stephane


Posted By: Delta558
Date Posted: 27 May 2018 at 8:17pm
Hi Stephane,

I think we're at crossed sims here! From your post in the other thread I believe you're referring to the X-Plane version, my comments are regarding the FSX/P3D version and as I don't have X-Plane I can't compare the two - different teams and I am unsure how the fde work is done for that.

My comments regarding the flaps are based on the latest revision for FSX and P3D, which should give a strong pitching up motion. The 152 pilots I refer to were testing the FSX/P3D version, NOT the X-plane version.

What I do find very interesting is your comment about the CG being above the centre of thrust line - it would explain and may be a way forwards. However, in the FSX/P3D fde that I built, the CG is located exactly on the position shown in the aircraft manual (diagram shown below:)
http://s956.photobucket.com/user/delta558/media/152%20CG.jpg.html" rel="nofollow">

If the diagram / manual is showing the CG incorrectly, it may well explain the reticence for the aircraft to pitch on throttle movement. Unfortunately, I can only go on what I have in front of me in black and white as it is generally classed as solid reference material.

I'm not sure how many of your points in the other thread may apply to both sims or if they are specific to the sim you are using. However, that is really good info (particularly speeds for RPM in specific configs) and is exactly the sort of thing I find useful when fine-tuning a flight model so I will 'borrow' that list at some point soon and run it through my sim fde to check and adjust accordingly.

Thanks for the input, really helpful even though it originated from the 'other' sim,
Paul.


Posted By: stephane130281
Date Posted: 27 May 2018 at 8:40pm
Hi Paul,

Glade that you read my post. Many thanks. My long list has also few stuff that could be solved easily like being able to key bind the fuel shutoff valve and the primer lever. Same for the tips, one should have the possibility to turn it off. That would help.

Regarding the flight dynamic, I was refering to the xplane 11 version, I apologize for jumping in the fsx/p3d topic. But the observations were the same.
I m really surprised hearing that an actual instructor is happy with the flaps behavior.
Regarding the CG depicted on the diagram, I think it is just a fictive position just to illustrate a typical CG position to give an idea. The actual CG might be a bit higher tho.
I ll be happy to help with the flight dynamic. If you need more accurate input or RPM settings based on the flight config just let me know.

Good luck and thanks again for this nice aircraft!

Regards
Stephane



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