Prop Reverse for pistons

[ptrev]

Has anyone solved reverse for pistons yet? The P2V7 has it but it is not as powerful as I remember in the only landing I had in an RAAF Neptune. The C123 and Albatross really need this feature. I remember a thread on the subject some time ago but nothing eventuated. Maybe one of the really savvy guys know how to do it.

Cheers :kilroy: Philip

[ryanbatc]

I don't understand...

You mean beta range for turboprops?

[Willy]

California Classics has been doing it with their FS9 propliners for a while. If it can be done there, I don't see why not in FSX.

[PRB]

And the Alphasim C-7 Cari-boo has reverse props too.

[Tako_Kichi]

So does the A2A B377.

[ptrev]

Hi Willy, Thanks for the tip. I'll feret around in their models to see how it'd done.(hopefully).

to ryanbatc, Just garden variety reversable props for pistons, usually on big radials. Ideal to save wear and tear on brakes and tyres. Don't think they were ever used like beta with turboprops.

For my one flight in an RAAF P2V7 my takeoff and landing position was strapped facing backwards on the floor at the rear of what I assume was the bomb bay bulkhead wall. Acceleration on takeoff left belt imprints on my body and reverse on landing left my body imprint in the metal behind me. Cool stuff for a young cadet.

cheers mates.

[falcon409]

I may be wrong, but I don't think he's asking if it can be done. . .he wants to know how. Does it take additional lines in the cfg file, does it have to be modeled into the aircraft, how would we know by looking in the cfg if it already has that option, if it has that option how is it initiated on landing. . .etc, etc.

[GypsyBaron]

Looking at three aircraft.cfg files I have for prop planes that
have reverse thrust I copied out the salient lines of the
cfg file Propeller section.

Try inserting/modifying your prop aircraft with the data
items below:



[propeller]
prop_reverse_available=1.000000
minimum_reverse_beta=-14.000000
minimum_on_ground_beta=1.000


Then use the F1 key to get the engines to idle then
use the F2 key ( held down ) to enter reverse pitch.

Use the F3 key to increase the pitch and rpm out of the reverse zone.

I have also seen the "minimum_reverse_beta" as -25 and
the "minimum_on_ground_beta" at 20.

Paul

[falcon409]

Thanks Paul, I'm going to look deeper into the C-123 cfg file now.:salute:

NOTE: the lines are present in the cfg file, just not active (all zeroed out). Gone to run a few tests.

[ptrev]

Falcon 409 is so right.

GypsyBaron, thanks heaps. You have saved me having to use up my own brain cells. I will try those numbers and let you know how I went.

Where would we be without the great folks who hang out at SOH? Now I'm off to drive some round engine a/c backwards. I guess I can substitute the keyboard commands with my throttle and pitch levers on my Saitek yoke as per the P2V7.

Philip:applause:

[falcon409]

Well, in a very short roll and initiate the reverse prop it stops quickly. . .on a full landing with touch down around 80kts, it rolled for about 100yds past the airport, lol. I think more testing is in order, lol.:salute:

[sparks]

Many turboprops have been produced with prop reverse (the default Beech King Air 350 for example), so I assume the question is with respect to prop planes with piston engines.

In FSX the aircraft.cfg parameter 'prop_reverse_available' is a scalar. It can be set to 0, 1, 5, 10 or whatever works best for a particular flight model. The higher the number, the more reverse thrust. Be careful though, too much reverse thrust will set your plane on its tail.

When all else fails, read the SDK:

prop_reverse_available

Specifies the scalar on the calculated propeller reverser effect. A value of 0 will cause no reverse thrust to be available. A value of 1.0 will cause the theoretical normal thrust to be available. Other values will scale the normal calculated value accordingly.

[ptrev]

You did better than me Falcon 409. I get nothing! Same with the Albatross. Gotta be more to it than just the propellor numbers. Anyone got a clue?

[Rich]

This was posted on SOH a couple of years ago and is not being claimed as my work except the key allocations at the bottom

revised inctuctions
--------------------------------------------------------------------------------

Step 1
Find an aircraft that needs reverse pitch props and go to its aircraft.cfg file.
This should work for all constant speed prop aircraft. Go to the prop section and find this:
prop_reverse_available = 1
minimum_on_ground_beta = 1
minimum_reverse_beta = -14
If the section is already like this, leave it, if not change to the above values or add them.
Step 2
Next go to
beta_max =
Now take the value there and subtract 1 and make it a negative # and put it in the
beta_feather =
Area.
(If there is no feather value they will need to be added)
Step 3
You must make sure that the
power_absorbed_cf =
Has a value of 0.1 if not props will go out of control.
Also make sure that the
min_rpm_for_feather =
is 0
Step 4 test!
Use the steps below to test while aircraft is at a standstill. If it moves backwards you did it!
(Note: make aircraft is not overloaded before testing.
Use in the sim
To make the props reverse do these following steps:
1. Once on ground hit Ctrl + F1. (Or move prop pitch lever all the way back
2. Then hold Ctrl + F2
You will see on the rpm gauge that the rpm drops below its usual minimum. As soon as you see that, then advance the throttle.
3. To return props to normal hit Ctrl + F4. (Or move prop pitch lever all the way forward
4. That’s it!

I have changed my key assignments as follows to give single keystrokes
Propeller RPM low changed to 5 was Ctrl + F1
Propeller RPM decrease quickly to 6 was Ctrl + F2
Propeller RPM high to 7 was Ctrl +F4
So on touchdown throttles closed tap 5 closely followed by 6 at the same time opening the throttles, as soon as speed drops low enough close throttles tap 7 and continue to taxi
The 5 6 7 nums are the main keyboard not the nums on the right

Prop section from my Blackburn Beverley which reverses nicely

[propeller]
propeller_type=0
propeller_diameter=16.5
propeller_blades=4
propeller_moi=37.375488
beta_max=65.0
beta_min=25.0
min_gov_rpm=1400.0
prop_tc=0.1
gear_reduction_ratio=2.25
fixed_pitch_beta=20.0
low_speed_theory_limit=80.0
prop_sync_available=0
prop_deice_available=1
prop_feathering_available=1
prop_auto_feathering_available=1
min_rpm_for_feather=20.0
beta_feather=-64.0
power_absorbed_cf=0.1 //9
defeathering_accumulators_available=1
prop_reverse_available=1
minimum_on_ground_beta=1
minimum_reverse_beta= -20 //-14.0

[Lewis-A2A]

The 377 from us is still I believe one of the only aircraft on the market that models it corectly thanks to sim connect etc.

[Bjoern]

California Classics has been doing it with their FS9 propliners for a while. If it can be done there, I don't see why not in FSX.

By the way, their aircraft work beautifully in FSX - including prop reverse.

Installing them however is a slight mess with all kinds of documentation scattered around the folders.

[LonelyplanetXO]

Hi, I dont use FSX but check Tom Clayton's post #15 of this thread...

http://www.sim-outhouse.com/sohforums/showthread.php?t=25655

maybe it works for FSX too...

He does say it's not a default behaviour but perhaps analysis of the Connie's air file might reveal the secret.

LPXO

[falcon409]

Rich,

I went through your step by step instructions for the C-123 cfg file and it made no difference. I have the throttle tab on my Logitech 3D Extreme Joystick set to adjust prop axis/pitch, so I used that along with the adjustments to the cfg but I saw no change.

I'm in and out of the house today running errands, so when I have time to sit down and take a closer look at the numbers I'll see if there's a problem somewhere that I may have missed.