Ground Idle too fast!

[Duckie]

Flying Tim Piglet Conrad's OV-1s - great model - but the gound idle speed is way too fast. Upon engine start they each go to 100% then return to idle. If the parking brake is not set it will ground loop! The brakes just barely hold it at idle. With brakes off at idle it's up to 60 in no time.

I've checked my throttle calibration and it's OK -- works the way it's supposed to on all other aircraft.

On landing without using reverse props I can get it stopped on a long runway. Unsing reverse pitch slows it down but full brakes are necessary for almost the entire length of a 5K runway, with touch down at about 100.

Is there a config adjustment I can make to correct this? If so can someone tell me what and how to do it?

I actually crewed (TO) the right seat for six years and would love to get it to act like I remember it.

Thanks for any and all help.

Duckie

[Z-claudius24]

Hi,

Aircraft.cfg

Experiments !

You can increase the bold number: (increase the brake effect)


[brakes]
toe_brakes_scale = 0.85
parking_brake = 1

For the idle problem you can decrease the bold number: (reducing the idle prop pitch)

prop_reverse_available = 1
minimum_on_ground_beta = 1

And increase (negative) the bold number (more reverse effect)

minimum_reverse_beta = -14
rotation = 1, 1

[Z-claudius24]

Hi,

My little tweaks on this bird (just installed and tested)

description=U.S. Army battlefield observation and recon aircraft. Also used for electronic warfare and monitoring by altering the sensors and their configuation. Easily recognized by its bug-eyed canopy, triple fin tail, and top mounted engine nacelles, in addition to the low slung SLAR external pod. Early Mohawks saw action in Viet Nam as armed attack planes, being called the JOV-1A.
Also used by Argentina, and formally by Israel, with demo examples briefly flown in West German and French markings. Various civil and non military agencies have also used Mohawks for drug interdiction, survey mapping, and atmospheric studies.
visual_damage=1
prop_anim_ratio = 1.72

Contacts points (so no noze wheel burried in ground when braking !)

[contact_points]
static_pitch = 2.49
static_cg_height = 5.32
max_number_of_points = 7

point.0 = 1, 10.2157, 0, -6, 1574, 0, 0.85, 60, 0.245, 1.5, 0.8, 4.8, 4.8, 0, 184, 184
point.1 = 1, -1.6933, -4.2273, -5.6598, 1574, 1, 1.1, 0, 0.642, 2.5, 0.8152, 4.5, 5.2, 2, 184, 184
point.2 = 1, -1.6698, 4.1482, -5.6598, 1574, 2, 1.1, 0, 0.642, 2.5, 0.8152, 5, 6, 3, 184, 184
point.3 = 2, -0.5038, -24.1473, 2.0418, 787, 0, 0, 0, 0, 0, 0, 0, 0, 5
point.4 = 2, -0.7937, 24.1478, 1.9996, 787, 0, 0, 0, 0, 0, 0, 0, 0, 6
point.5 = 2, -23.5674, 0, 0.5491, 787, 0, 0, 0, 0, 0, 0, 0, 0, 9
point.6 = 2, 5.4886, 0, -2.5587, 787, 0, 0, 0, 0, 0, 0, 0, 0, 4
gear_system_type=1

Propeller

[propeller]
thrust_scalar=1
propeller_type=0
propeller_diameter=10.5
propeller_blades=3
propeller_moi=36.1
beta_max=65
beta_min=15
min_gov_rpm=7500
prop_tc=0.01
gear_reduction_ratio=5.6
fixed_pitch_beta=25
low_speed_theory_limit=80
prop_sync_available=1
prop_deice_available=1
prop_feathering_available=1
prop_auto_feathering_available=1
min_rpm_for_feather=700
beta_feather=88.5
power_absorbed_cf=0.9
defeathering_accumulators_available=0
prop_reverse_available=1
minimum_on_ground_beta=0.5
minimum_reverse_beta=-16
rotation = 1, 1

Brake

[brakes]
toe_brakes_scale =1
parking_brake = 1

Seem's nice for me .....

[Z-claudius24]

Hi,

Tests continued (in flight now)

I changed the smoke effect with the recent released for the Milton Dash 7
Seem's the smoke of those engine exagerated with the original smoke effect.
Never been in this plane so dunno if it's realistic .. but when you drop the landing gear ... the plane drop also (noze go brutally down) .. like a stone (at any speed)
And when you drop the flaps .. it's the contrary effect .. the plane jump ...
So if Duckie can comment on this from the right seat ?

Attachment 2847

It's not so simple like in the book (as always) .. cause the panel provided with the plane is not equiped with a pedestal ...
So it's to use some keyboard commands ? .. good luck
Of course it's always possible to add a pedestal and all to the panel .... or use a other panel !

[TARPSBird]

Duckie, after reading your post I d/l'ed and flew Piglet's OV-1B and OV-1D and I couldn't duplicate the ground idle problem you have. Looks like the .air and .cfg values are the same for both. I didn't even have to use brake on start-up. I landed at about 95-100 KIAS over the numbers at Palwaukee (KPWK) and got both aircraft stopped OK with plenty of runway left.

[Duckie]

Thanks very much claudius24 for the investigation and config settings. I'll have a look at your numbers.

Never been in this plane so dunno if it's realistic .. but when you drop the landing gear ... the plane drop also (noze go brutally down) .. like a stone (at any speed)
And when you drop the flaps .. it's the contrary effect .. the plane jump ...
So if Duckie can comment on this from the right seat ?

The OV-1 had a very high sink rate, especially the "C" with its stubby wings. It "rode" like a high performance car with stiff shocks crossing railroad tracks! You felt everything. Almost every control input translated into a thump in your butt! Night IR missions were the worst (for me) becasue your face stayed glued to he scope and you were constantly "punching and updating" the Doppler coords marking targets. This made for some miserable flying if the air was rough. But it was flying and I would have changed a thing!

TARPSBird
Duckie, after reading your post I d/l'ed and flew Piglet's OV-1B and OV-1D and I couldn't duplicate the ground idle problem you have. Looks like the .air and .cfg values are the same for both. I didn't even have to use brake on start-up. I landed at about 95-100 KIAS over the numbers at Palwaukee (KPWK) and got both aircraft stopped OK with plenty of runway left.

Hey TARPS, thanks for having a look. I just installed them again last week and first chance I had to fly them was yesterday evening. Maybe the insatll was corrupt? I'll try downloading them again and a new install. I don't remember having this problem before.

Anyway, thanks to you both for having a look and replying. I'll let you know what happens from here.

Cheers,
Duckie.

[Tom Clayton]

One thing that has helped me with several t-props is to pull the condition lever back to 50% and the props all the way back to feathered. This prevent's most t-props from trying to move with the brakes released.

[Z-claudius24]

Hi,

One thing that has helped me with several t-props is to pull the condition lever back to 50% and the props all the way back to feathered. This prevent's most t-props from trying to move with the brakes released.

This was my answer to a deleted post of
srgalahad

It's not so simple like in the book (as always) .. cause the panel provided with the plane is not equiped with a pedestal ...
So it's to use some keyboard commands ? .. good luck
Of course it's always possible to add a pedestal and all to the panel .... or use a other panel !

The panel provided with this plane don't contain a 2D pedestal and in the VC pedestal the condition levers are not active !

[Duckie]

Well, it seems the config tweeks didn't help except for the nose gear contact point adjustment.

However, the immediate fix is the prop condition lever adjustment, as you botjh suggested Although there is not a 2D pedistal, the levers in the 3D pit work just fine. I fly from teh 3D pit and the engine start panel is clickable in the 3D pit.

I have mapped lever control to my throttle buttons - one to increase pitch, the other to decrease it. I already had reverse thrust mapped.

I just have to remember to adjust the props BEFORE I start engines! Let's see where's that checklist!

Thanks very much for the suggestions, Tom and Claudius.

Duckie

[Tom Clayton]

If you need a 2D throttle section, just copy the one from the stock King Air.

Additionally, the C208B can be used to scavenge a single t-prop throttle, and both Avsim and Flightsim have "4engtptq.zip", which is a quad mod of the stock King Air set.

[Duckie]

Thanks very much Tom but I rarely use the 2D pit, only when I need something that isn't available in the 3D will I switch over. So, I'm good with the workaround above.

Been flying some this afternoon and it works just fine. The landing is a challenge for tactical approaches because I can't get it slowed down enough. The real one could almost stop on a dime! This one, or at least mine, won't stop in a 40 acre field unless you mak a loooong stateside approach with everything hangin' out for a few miles.

I've had some hard landings in the RW OV-1 due to my left seater being all to eager to go to full reverse...still a few feet off the ground! That'll jar your kidneys. And if the old man happened to see it you might get to set down for a spell and put in charge of the officers' mess! Crew chiefs were not too happy either.

Cheers,
Duckie

[aeromed202]

Is it more aerodynamic drag needed or more braking once on the ground? With someone here who has logged time in the real thing I'd be up for some tinkering to get it right.

[Duckie]

Is it more aerodynamic drag needed or more braking once on the ground? With someone here who has logged time in the real thing I'd be up for some tinkering to get it right.

Hey aeromed, thanks~ It's just too much speed from start to finish. But this may be a problem peculiar to my set up. Tarpsbird (see above post) said his performs like it should. Although the real bird had some STOL charactoristics, the virtual one I have is a dragster!

Upon engine start up the virtual throttle goes to 100% with the hardware throttle pulled back to idle. Starting no.1 without brakes set with all other settings at default she'll ground loop to the right. The virtual throttle after 10 seconds or so returns to it's idle which acording to the RPM tape is about 70%.

I've pretty much taken care of that by going through a mini-check list that sets the props at full reverse and parking brake on before start up.

Once she's off the ground you have to hold her back by keeping the props pulled way back and the throttle at about 40%, if you don't she'll be up over 300 in no time. Tactical approaches, down the approach at cruise (about 210) with a left brake over the numbers throwing everthing out she just barely slows to 120 back over the numbers and that's pretty much where it stays. On touch down I have to add parking brake to get it stopped before she goes off the deep end.

I just want a slower Mohawk!

Any and all help is appreciated.

Duckie

[Z-claudius24]

Hi,

Landing ....

http://www.4shared.com/file/24795057...d2/Mohawk.html

That's not a STOL landing .. but no need of too much runway

[Duckie]

Great landing, claudius!

[srgalahad]

Hey aeromed, thanks~ It's just too much speed from start to finish. But this may be a problem peculiar to my set up. Tarpsbird (see above post) said his performs like it should. Although the real bird had some STOL charactoristics, the virtual one I have is a dragster!

Upon engine start up the virtual throttle goes to 100% with the hardware throttle pulled back to idle. Starting no.1 without brakes set with all other settings at default she'll ground loop to the right. The virtual throttle after 10 seconds or so returns to it's idle which acording to the RPM tape is about 70%.

I've pretty much taken care of that by going through a mini-check list that sets the props at full reverse and parking brake on before start up.

Nope, not just yours Duckie - but it's erratic when I test it (using AFSD to monitor the sim parameters).
I get the acceleration on the ground, but noticed that with my Saitek throttle pulled all the way back it still holds 0.6% throttle - a tap on F1 will drop throttle to 0.0% (so possibly a slightly worn 'pot' in the throttle), Beta (pitch) goes down to 1* and prop rpm to 1200-1250, thrust shows 380 lbs ( that's the residual exhaust thrust) -- and it will sit like a well-mannered child even without park brake on.

Anything that lets the throttle increase past 0.6% (like a gentle nudge) then starts the acceleration process described here:
In flight, the engine operates at a constant speed, which is maintained by the governing section of the propeller. Power changes are made by increasing fuel flow and propeller blade angle rather than engine speed. An increase in fuel flow causes an increase in temperature and a corresponding increase in energy available to the turbine. The turbine absorbs more energy and transmits it to the propeller in the form of torque. The increased torque forces the propeller blade angle to be increased to maintain the constant speed.. Physical pull on throttle + hitting F1 will get it back under control (most of the time unless speed gets too high).
http://www.pilotoutlook.com/airplane..._engines_types
(BTW, the T-53 should not have a separate pitch controller - see the link)

Once she's off the ground you have to hold her back by keeping the props pulled way back and the throttle at about 40%, if you don't she'll be up over 300 in no time. Tactical approaches, down the approach at cruise (about 210) with a left brake over the numbers throwing everthing out she just barely slows to 120 back over the numbers and that's pretty much where it stays. On touch down I have to add parking brake to get it stopped before she goes off the deep end.

Mutiple tests: power reduced, speed reduces normally. Gear at 140 kts, flaps as required... look at AFSD and hmmmmm
airspeed down to 90kts, throttle down to 0.6%, but props will not reduce below 25*, rpm not below 1600 and thrust NOT below 1000# or about 40% so no wonder it won't slow down. Any nose-down allows the plane to increase airspeed (naturally) but since the power stays up too....

Finally got it to lose power... throttle down, hit F1 then one or two taps on F2 (reverse) gets the props to slow, thrust to drop and then F1 again holds the low end of the power range. 0.0% throttle, thrust below 400#, prop rpm below 1300. (but must be repeated if you add power to avoid the trees at the end of the runway)
-- airfile is dated 16/10/2005, .cfg 6/11/05, .mdl 5/11/2005

So, I dunno... almost looks like broken prop governors

Rob

[Z-claudius24]

Hi,

For this landing I used additionally the air brakes but it's make not real differences ....

http://www.4shared.com/file/24803805...2/Mohawk2.html

[Duckie]

I think you agree with my analysis in laymen's terms?

Thank you very much Rob, and for providing some more work around buttons.

I'll give it a try tomorrow. I really do like this plane. Piglet did a great job getting the "look" of it. Now I just have to learn to fly it.

Cheers,
Duckie

[adhockey]

An idea I've kicked around some is a runway with tick-marks and numbers like a yardstick so you can see exactly how short your T/Os and landings are, e.g. zero to 5000 feet in 10 or 25 foot increments.

I know there is a standard length and distance to the painted white lines on RW runways, which could be used, but I just don't trust the sim to be perfect.

There is the other issue of the runway being bidirectional when you build it in afcad.

Just a thought.

[aeromed202]

I've worked on some of these before, there are several. I haven't compared CFGs yet so I don't know if they are interchangable. I picked one I'd done some work on which adds on with the title OV-1D_TNR with the variation name U.S. Army Trainer. I remembered it gave me conniptons. I seemed to bottom out on the adjustments when any further changes caused unacceptable problems in other areas. I haven't the software or know-how to play with models or air files so all I can do is decipher the CFG with whatever limits that puts on what I can do. I use videos whenever I can to help with realism but adhockey is right, I'd like at least one long runway marked to scale.

All that being said I'll put what I did here so you can see if it helps. I've got it to where it won't taxi until you apply power, approach at about 100 dirty with minimal power, and easily brake for a turnoff.

[Duckie]

I've worked on some of these before, there are several. I haven't compared CFGs yet so I don't know if they are interchangable. I picked one I'd done some work on which adds on with the title OV-1D_TNR with the variation name U.S. Army Trainer. I remembered it gave me conniptons. I seemed to bottom out on the adjustments when any further changes caused unacceptable problems in other areas. I haven't the software or know-how to play with models or air files so all I can do is decipher the CFG with whatever limits that puts on what I can do. I use videos whenever I can to help with realism but adhockey is right, I'd like at least one long runway marked to scale.

The D-Trainer is the one I'm working with but a quick scan of all 4 versions of the OV-1 says they're all pertty much alike in the CFG perfromance catagories.

All that being said I'll put what I did here so you can see if it helps. I've got it to where it won't taxi until you apply power, approach at about 100 dirty with minimal power, and easily brake for a turnoff.

THAT IS EXACTLY WHAT I WANT IT TO DO! (as well as fly decently! )

Thanks aeromed, looking forward to a test flight.

I like the measured and marked runway idea too. It would be good to have one such runway marked for L - T/O practices for us to practice getting it right!

Cheers
Duckie

[aeromed202]

Going to take a bit longer. She rolls badly on rudder input so let me get that under control. Should be today though. Have another joe.

[aeromed202]

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Ongoing issues:
*strangely wants to accelerate after landing if you release the brakes until you get down to 20 or below then it starts to behave.
*still nose dives a little when dropping the gear
*persistent roll issue on rudder input-the wrong roll direction but not so severe now

Use the air brakes as needed to get down to about 120 then incremental flaps should apply enough drag to not need them any more. Areas I adjusted are contact points, flight dynamics, brakes, flaps (took 2 sections out too), MOI's, CG, engine thrust/power/location, and airplane geometry.
Ok I can't add the attachment. I'll try a little later.

[Duckie]

=aeromed202; Ok I can't add the attachment. I'll try a little later.

WHEW! I'm glad you clarified that!

Duckie

[srgalahad]

I've worked on some of these before, there are several. I haven't compared CFGs yet so I don't know if they are interchangable. I picked one I'd done some work on which adds on with the title OV-1D_TNR with the variation name U.S. Army Trainer. I remembered it gave me conniptons. I seemed to bottom out on the adjustments when any further changes caused unacceptable problems in other areas. I haven't the software or know-how to play with models or air files so all I can do is decipher the CFG with whatever limits that puts on what I can do. I use videos whenever I can to help with realism but adhockey is right, I'd like at least one long runway marked to scale.

That's exactly why I get concerned about partial fixes and "shadetree" repairs I see all the time. Certainly, sometimes a one-line change can fix a problem, but for others there are so many related components that a small 'fix' upsets another part of the FM.
In addition, thinking that the original modeler spent months making everything work, how extensively do some of these changes get tested through the entire flight regime before they get posted as "This will fix your problem"? and is the change "correct" as opposed to "convenient"...but that's a discussion for another time and place...

All that being said I'll put what I did here so you can see if it helps. I've got it to where it won't taxi until you apply power, approach at about 100 dirty with minimal power, and easily brake for a turnoff.

Even with the quirky throttle responses I posted above, it seems to settle down fine on the ground - on approach the power issues are less pleasant but I too can get it to a 100kt approach (noting the stall speeds are a lot lower than that) , but I have done nothing to the .cfg or airfile... just refining pilot technique. However, it's odd that at least Duckie and I have this problem, but TARPS and John have no issues... which leads me to wonder if it's something in the coding deeper within the model.

Carrying on....

Rob