Properties of Piper Comanche 250?

Post any technical issues here. This forum gets priority from our staff.
new reply
User avatar
Alex56
Airman First Class
Posts: 59
Joined: 23 Jun 2017, 01:54
Location: Ukraine, UKDE
Contact:

Properties of Piper Comanche 250?

Post by Alex56 »

Hello. I have long wanted to ask questions.
Please, first question: I have Prepar3Dv3. I flew on the default Bonanza A36. If I climbed to altitude at 2,700 feet or more without adjusting the mixture, rpm began to decrease. Now I have the A2A Comanche 250. When I go up to 5000-6000 feet, the rpm does not change. What corresponds to reality: the default Bonanza A36 or A2A Comanche 250?
The second question: at 2400 rpm of the engine and a light propeller in a horizontal flight, the speed of the aircraft does not increase more than 120 kt. Is this normal?
The third question: I know, usually when the flaps are released, the nose of the aircraft rises slightly. When flaps are removed, the nose of the aircraft slightly drops. In my A2A Comanche 250 conversely. Is this normal for this type of aircraft?
Thanks. Sincerely, Alexander.

User avatar
Nick - A2A
A2A Captain
Posts: 13728
Joined: 06 Jun 2014, 13:06
Location: UK

Re: Properties of Piper Comanche 250?

Post by Nick - A2A »

Hello Alexander - I'll do my best to give some answers, though there are those with real-world Comanche time who can probably do a better job.
Alex56 wrote:Please, first question: I have Prepar3Dv3. I flew on the default Bonanza A36. If I climbed to altitude at 2,700 feet or more without adjusting the mixture, rpm began to decrease. Now I have the A2A Comanche 250. When I go up to 5000-6000 feet, the rpm does not change. What corresponds to reality: the default Bonanza A36 or A2A Comanche 250?
One fairly well known bug in FSX/P3D is the need to lean the mixture unrealistically early and aggressively to avoid power loss. A2A addressed this behaviour with Accu-Sim and the behaviour that you're seeing in the Comanche is more realistic.
Alex56 wrote:The second question: at 2400 rpm of the engine and a light propeller in a horizontal flight, the speed of the aircraft does not increase more than 120 kt. Is this normal?
No, that definitely isn't normal if you're talking about indicated airspeed (shown in MPH on the ASI) or true airspeed. Are you perhaps looking at groundspeed instead, and flying into a headwind? Also, what sort of altitude are we talking about here?
Alex56 wrote:The third question: I know, usually when the flaps are released, the nose of the aircraft rises slightly. When flaps are removed, the nose of the aircraft slightly drops. In my A2A Comanche 250 conversely. Is this normal for this type of aircraft?
Thanks. Sincerely, Alexander.
Yes, a nose down pitch response is typical for flap extension with low-winged GA aircraft whereas high-winged types such as Cessnas will tend to exhibit a nose-up pitch response to dropping the flaps. (However, there are certainly some exceptions to this.) I'm sure the A2A team modelled the pitch response to flap extension in the correct direction in the A2A Comanche based on Scott's experience in the real aircraft. :wink:

Cheers,
Nick

User avatar
AKar
A2A Master Mechanic
Posts: 5207
Joined: 26 May 2013, 05:03

Re: Properties of Piper Comanche 250?

Post by AKar »

Alex56 wrote:Please, first question: I have Prepar3Dv3. I flew on the default Bonanza A36. If I climbed to altitude at 2,700 feet or more without adjusting the mixture, rpm began to decrease. Now I have the A2A Comanche 250. When I go up to 5000-6000 feet, the rpm does not change. What corresponds to reality: the default Bonanza A36 or A2A Comanche 250?
With constant speed prop, the RPM only drops if you are significantly under-powered. And not always even then: at high-enough airspeed, with your fuel at cut-off, the RPM should remain constant even while your engine is off. The description of A36 is totally off.

-Esa

User avatar
Alex56
Airman First Class
Posts: 59
Joined: 23 Jun 2017, 01:54
Location: Ukraine, UKDE
Contact:

Re: Properties of Piper Comanche 250?

Post by Alex56 »

AKar wrote:
Alex56 wrote:Please, first question: I have Prepar3Dv3. I flew on the default Bonanza A36. If I climbed to altitude at 2,700 feet or more without adjusting the mixture, rpm began to decrease. Now I have the A2A Comanche 250. When I go up to 5000-6000 feet, the rpm does not change. What corresponds to reality: the default Bonanza A36 or A2A Comanche 250?
With constant speed prop, the RPM only drops if you are significantly under-powered. And not always even then: at high-enough airspeed, with your fuel at cut-off, the RPM should remain constant even while your engine is off. The description of A36 is totally off.

-Esa
Thank you.

User avatar
Alex56
Airman First Class
Posts: 59
Joined: 23 Jun 2017, 01:54
Location: Ukraine, UKDE
Contact:

Re: Properties of Piper Comanche 250?

Post by Alex56 »

Alex56 wrote:The second question: at 2400 rpm of the engine and a light propeller in a horizontal flight, the speed of the aircraft does not increase more than 120 kt. Is this normal?
Nick M wrote:No, that definitely isn't normal if you're talking about indicated airspeed (shown in MPH on the ASI) or true airspeed. Are you perhaps looking at groundspeed instead, and flying into a headwind? Also, what sort of altitude are we talking about here?
I talking about indicated airspeed (shown in MPH on the ASI 120 kt ), altitude 3000ft, no wind. The speed becomes faster if I increase the rpm to 2500, but with such rpm it is always forbidden to fly. I never hold a rpm 2500 for a long time.

User avatar
Nick - A2A
A2A Captain
Posts: 13728
Joined: 06 Jun 2014, 13:06
Location: UK

Re: Properties of Piper Comanche 250?

Post by Nick - A2A »

Alex,

Have you checked the state of the engine in the maintenance hangar (shift 7)? It sounds like it's not developing full power for some reason. Presumably the throttle is fully open in the situation you describe but did you happen to note the manifold pressure?

Thanks,
Nick

User avatar
Oracle427
Chief Master Sergeant
Posts: 3916
Joined: 02 Sep 2013, 19:30
Location: 3N6
Contact:

Re: Properties of Piper Comanche 250?

Post by Oracle427 »

Gear up and flaps up?
Flight Simmer since 1983. PP ASEL IR Tailwheel
N28021 1979 Super Viking 17-30A

User avatar
Alex56
Airman First Class
Posts: 59
Joined: 23 Jun 2017, 01:54
Location: Ukraine, UKDE
Contact:

Re: Properties of Piper Comanche 250?

Post by Alex56 »

Oracle427 wrote:Gear up and flaps up?
Yes of course – gear up, flaps up. In the flight, I specifically checked it with an external video camera.

User avatar
Oracle427
Chief Master Sergeant
Posts: 3916
Joined: 02 Sep 2013, 19:30
Location: 3N6
Contact:

Re: Properties of Piper Comanche 250?

Post by Oracle427 »

Do you have a spoiler axis mapped to your controls? This can interfere with proper operation if the spoiler axis is extended at all.

This is a sim bug/feature, that all aircraft get a "apoiler" whether one is modeled or not.
Flight Simmer since 1983. PP ASEL IR Tailwheel
N28021 1979 Super Viking 17-30A

User avatar
Alex56
Airman First Class
Posts: 59
Joined: 23 Jun 2017, 01:54
Location: Ukraine, UKDE
Contact:

Re: Properties of Piper Comanche 250?

Post by Alex56 »

Nick M wrote:Alex,

Have you checked the state of the engine in the maintenance hangar (shift 7)? It sounds like it's not developing full power for some reason. Presumably the throttle is fully open in the situation you describe but did you happen to note the manifold pressure?

Thanks,
Nick
Before each flight I check the status in the hangar (Shift + 7), the resolution is like a new one, the state is beautiful. I check the compression: if the compression is not very good, then repair it. I check around the plane (shift+8). Only after that I leave on the taxiway. Before each take-off I check the state of the magneto (turn it off alternately with rpm 2000: L-both, R-both, and both), braking and smoothly (for 3 seconds) give the full engine power on RWY before take-off - the power is good, all right, rpm max 2500.

I do not understand the MP parameters very well. Now I'm studying what is the MP detail. In flight I wrote down the readings of the MP:
rpm 2400 MP = 16
rpm 2500 MP = 29
On a parking place
rpm 1000 MP = 14
rpm 2000 MP = 20.1
Last edited by Alex56 on 11 Nov 2017, 12:19, edited 1 time in total.

User avatar
Oracle427
Chief Master Sergeant
Posts: 3916
Joined: 02 Sep 2013, 19:30
Location: 3N6
Contact:

Re: Properties of Piper Comanche 250?

Post by Oracle427 »

MAP 16 is very low for cruise. That is a descent power setting. It should be in the low 20's or high teens.

Also, double check that spoiler axis mapping, but if you are cruising at 16 in.hg. MAP, then that explains your slow airspeed.
Flight Simmer since 1983. PP ASEL IR Tailwheel
N28021 1979 Super Viking 17-30A

User avatar
Alex56
Airman First Class
Posts: 59
Joined: 23 Jun 2017, 01:54
Location: Ukraine, UKDE
Contact:

Re: Properties of Piper Comanche 250?

Post by Alex56 »

After your information about the MP, I made a test flight, in which I controlled the pitch of the propeller in another way. As a result, I reached a horizontal speed of 180 knots! with rmp 2400 and MP 27. Now I understand how to control the pitch of the screw. Oh oh! :) Thanks to everyone! Thanks!
P.S. I know what a spoiler is, but I do not know where it is on this plane. Give me a link to read about spoiler, if it's not difficult for you. Thanks.

User avatar
Nick - A2A
A2A Captain
Posts: 13728
Joined: 06 Jun 2014, 13:06
Location: UK

Re: Properties of Piper Comanche 250?

Post by Nick - A2A »

Glad you seem to have solved the low MAP issue Alexander. I'm not clear exactly what the problem was, but it sounds like you've mapped your controls differently. Another thing to consider if you notice an unexplained reduction in MAP in future would be carburettor icing.

As regards the spoiler, Oracle427 was just pointing out that sometimes in FSX/P3D the spoiler axis can still have an aerodynamic effect, even if the aircraft in question isn't actually fitted with spoilers. It's just a quirk of the simulator.

Thanks,
Nick

User avatar
Alex56
Airman First Class
Posts: 59
Joined: 23 Jun 2017, 01:54
Location: Ukraine, UKDE
Contact:

Re: Properties of Piper Comanche 250?

Post by Alex56 »

Many thanks. I did not know how to properly use the propeller pitch. Now I felt it in practice and understood how it works. I know about the carburetor icing and know that this can make the engine work not stable. I flew in cold weather and applied the carburetor heating - the engine worked well. All the best to you, Nick!

new reply

Return to “Piper Comanche 250 Tech Support”

Who is online

Users browsing this forum: No registered users and 7 guests