Talk:Cessna 172P

I am enjoying flightgear. Thank you.

A note of a bug from programmer to programmer:

 The torque pulls the 172p to the right on the first
 take-off rather than to the left as it does in reality.
 When rudder is applied to compensate the plane goes a
 bit wacky as the wheels leave the ground.  The plane turns
 into a left bank.

 This problem does not appear in cruise where the rudder
 seems to work fine.

 It may be my imagination, but I'm pretty sure that the
 second take-off in a session does not have the problem.

 Could be a variable improperly initialized.

Joystick CH 568 Combatstick USB Rudders CH Pro Pedals USB

Dave Inman Comm+Inst Pilot 25 yrs software development

Can't stall

I tried doing a power-off stall, like students do when first learning to fly. Specifically, imitating the procedure that was used at my flight school:

• 65KIAS
• Flaps down
• 1500 rpm

Then:

• Engine idle
• Rotate into stall attitude
• Let airspeed drop below 40KIAS, using backpressure and trim to maintain the attitude

What happens? The real airplane will jerk its nose down soon after reaching 40kts, and can descend sharply if corrective action is not taken.

In the model, you can hold the nose up indefinitely, and the airplane will gently descend at about 1000 fps, with the stall horn blaring.

Aren't there any better Cessna 172 models than this out there? Un 00:40, 28 June 2010 (UTC)

---

Hi, The wiki is the place for collecting informations for users- but not for bug reports! Please use the developers-mailinglist, the official flightgear bugtracker at google or the forum.

The c172p is approved in many things by some other reallife pilots, but still there are issues left due to fdm-limits. Some can may be fixed now -so please contact as written above!

HHS 18:43, 28 June 2010 (GMT+1)

Unrealistic flight performance issue, previously listed under Development status/Issues/Todo

The following, questioning the flight performance, was previously listed under Development status; I've moved it here, since it's really a user objection rather than a confirmed development issue.

General:

• It is routine to observe 135 Kias at 2850 RPM in level flight at 1000 MSL, using only 13 gph. This is not the sort of performance seen in real-life Skyhawks.
  • What is the expected performance according to your estimation?

This comment was posted four years ago, with the summary "wildly unrealistic performance", but the user never answered the response.

I've just done a test myself on the latest Flightgear 2.4.0, using the C172P loaded to about 1900 lb gross weight, and I got 140 KIAS at 2860 RPM in level flight at 1000 ft MSL, using 13.85 gph. Throttle was at 93%, mixture full rich.

It's possible this does show deficiencies in the model, but I'm not sure how reasonable this test is. The resulting power (2*pi * 2860 RPM * torque of 281.7 lb-ft) is 153.3 hp, which is nearly full engine power (listed as 160 hp at 2700 RPM). But 2700 RPM is the engine's redline, so here the engine is being run beyond the redline. No real Skyhawk would be operated that way, so this isn't a test that can be verified with a real airplane. The user also wasn't specific on their objections: is the speed too high? Or perhaps a real Skyhawk could be flown at this speed, but at a lower engine RPM, perhaps with greater fuel consumption?

In any case, I think a more useful test would be to reproduce conditions listed in the Cessna 172P flight manual, such as cruise performance, and compare the performance achieved in the simulator.

--Colin Douglas Howell 16:06, 22 August 2011 (EDT)