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P3D v4 Prop Strike Continuous Problem

lionheart

lionheart

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us-arizona
Hey all,

I seem to have found a problem on my newest bird. I keep getting a prop strike. I land on a grass runway and Bammo... Prop strike, engine stops.

My prop diameter entry isnt huge. Where might one find the culprit that is causing this? How does the sim know where the bottom edge of my propeller is? Could it be based on the engine location?


Bill
LHC
 
Engine location (in the vertical plane) plus prop diameter, I figure.
 
Thats what I thought. Its not working. I'll raise it up 2 feet and see if that fixes it, lol...
 
Is it a tail dragger? If so it can land in a horizontal attitude (and take off) which would put the prop lower than the tail down geometry would suggest.
Roy
 
Thanks Roy. Its a tricycle, but using the FSX Extra 300 template. I raised the prop (engine location) up and that didnt help. Never had this happen before. Very odd.
 
Roy,

What else might cause prop strike? Could it be a contact point? I tried moving the engine location up and that made the plane handle odd.
 
Here are the data sections, first is mine, second is the Extra;

Tango;

[propeller]
thrust_scalar = 0.6 //Propeller thrust scalar
propeller_type= 1 //0=Constant Speed, 1=Fixed Pitch
propeller_diameter= 5.0 //Propeller Diameter, (feet)
propeller_blades= 2 //Number of propeller blades
propeller_moi= 3.78 //Propeller moment of inertia
beta_max= 0 //Maximum blade pitch angle for constant speed prop, (degrees)
beta_min= 0 //Minimum blade pitch angle for constant speed prop, (degrees)
min_gov_rpm= 0 //Miminum governed RPM
prop_tc= 0.1 //Prop time-constant
gear_reduction_ratio= 1.0 //Propeller gear reduction ratio
fixed_pitch_beta= 30.75 //Fixed pitch angle of fixed pitch prop, (degrees)
low_speed_theory_limit= 80 //Speed at which low speed theory becomes blended in (feet/second)
prop_sync_available= 0 //Prop synchronization available? 0=FALSE, 1=TRUE
prop_deice_available= 0 //Prop de-icing available? 0=FALSE, 1=TRUE
prop_feathering_available= 0 //Prop feathering available? 0=FALSE, 1=TRUE
prop_auto_feathering_available= 0 //Prop auto-feathering available? 0=FALSE, 1=TRUE
min_rpm_for_feather= 0 //Minimum RPM for prop feathering
beta_feather= 0 //Feathering pitch angle (degrees)
power_absorbed_cf= 0 //Coefficient of friction for power absorbed by propeller in feather
defeathering_accumulators_available= 0 //Defeathering accumulators available? 0=FALSE, 1=TRUE
prop_reverse_available= 0 //Prop reverse available? 0=FALSE, 1=TRUE
minimum_on_ground_beta= 0 //Miminum pitch angle on ground, (degrees)
minimum_reverse_beta= 0 //Minimum pitch angle in reverse, (degrees)

Extra 300;

[propeller]
thrust_scalar = 1.0 //Propeller thrust scalar
propeller_type= 0 //0=Constant Speed, 1=Fixed Pitch
propeller_diameter= 6.2 //Propeller Diameter, (feet)
propeller_blades= 3 //Number of propeller blades
propeller_moi= 5.9 //Propeller moment of inertia
beta_max= 34 //Maximum blade pitch angle for constant speed prop, (degrees)
beta_min= 17 //Minimum blade pitch angle for constant speed prop, (degrees)
min_gov_rpm= 1400 //Miminum governed RPM
prop_tc= 0.1 //Prop time-constant
gear_reduction_ratio= 1.0 //Propeller gear reduction ratio
fixed_pitch_beta= 0 //Fixed pitch angle of fixed pitch prop, (degrees)
low_speed_theory_limit= 80 //Speed at which low speed theory becomes blended in (feet/second)
prop_sync_available= 0 //Prop synchronization available? 0=FALSE, 1=TRUE
prop_deice_available= 0 //Prop de-icing available? 0=FALSE, 1=TRUE
prop_feathering_available= 0 //Prop feathering available? 0=FALSE, 1=TRUE
prop_auto_feathering_available= 0 //Prop auto-feathering available? 0=FALSE, 1=TRUE
min_rpm_for_feather= 0 //Minimum RPM for prop feathering
beta_feather= 0 //Feathering pitch angle (degrees)
power_absorbed_cf= 0 //Coefficient of friction for power absorbed by propeller
defeathering_accumulators_available= 0 //Defeathering accumulators available? 0=FALSE, 1=TRUE
prop_reverse_available= 0 //Prop reverse available? 0=FALSE, 1=TRUE
minimum_on_ground_beta= 0 //Miminum pitch angle on ground, (degrees)
minimum_reverse_beta= 0 //Minimum pitch angle in reverse, (degrees)

Tango Contact Points;

[contact_points]
static_pitch = 0.0
static_cg_height = 3.8
tailwheel_lock = 0
gear_system_type = 0
max_number_of_points = 9

point.0 = 1, 3.34, 0, -3.78, 2500, 0, 0.45, 36, 0.26, 1.500, 0.500, 0, 0, 0, 0, 0
point.1 = 1, -2.7, -3.27, -3.76, 3500, 1, 0.55, 0, 0.2, 2.5, 1.0, 0, 0, 2, 0, 0
point.2 = 1, -2.7, 3.27, -3.76, 3500, 2, 0.55, 0, 0.2, 2.5, 1.0, 0, 0, 2, 0, 0
point.3 = 2, -1.0461, -12.0937, 1.46, 1574.8, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0
point.4 = 2, -1.0901, 12.0822, 1.4314, 1574.8, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0
point.5 = 2, -15.4812, 0, -0.5438, 1574.8, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0
point.6 = 2, 3.2515, 0, -2.8, 2574.8, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0
point.7 = 2, -14.6123, 0, 2.7439, 1574.8, 0, 0, 0, 0, 0, 0, 0, 0, 7, 0, 0
point.8 = 2, -1.531, 0, -2.1838, 1574.8, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0

Extra Contact Points;
[contact_points]
point.0=1, -16.50, 0.00, -1.5, 1377.95, 0, 0.4100, 180.0, 0.4, 2.5, 0.6, 0.0, 0.0, 0.0, 0.0, 0.0
point.1=1, -0.05, -2.92, -4.4, 1968.50, 1, 1.1660, 0.0, 0.6, 2.5, 0.6, 0.0, 0.0, 2.0, 0.0, 0.0
point.2=1, -0.05, 2.92, -4.4, 1968.50, 2, 1.1660, 0.0, 0.6, 2.5, 0.6, 0.0, 0.0, 3.0, 0.0, 0.0
point.3=2, -1.40, -12.45, 0.0, 787.40, 0, 0.0000, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 5.0, 0.0, 0.0
point.4=2, -1.40, 12.45, 0.0, 787.40, 0, 0.0000, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 6.0, 0.0, 0.0
point.5=2, -16.10, 0.00, 5.2, 787.40, 0, 0.0000, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 9.0, 0.0, 0.0
point.6=2, 4.8, 0.00, 0.6, 787.40, 0, 0.0000, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 4.0, 0.0, 0.0

static_pitch = 10.54
static_cg_height = 3.45

// Note above, the static pitch and cg height are in the 'after' section of the contact points on the Extra, and on the top in the Tango. I wonder if that might be it?

Engine location on the Tango;

[GeneralEngineData]
engine_type = 0 //0=Piston, 1=Jet, 2=None, 3=Helo-Turbine, 4=Rocket, 5=Turboprop
Engine.0 = 3.5, 0.0, 0.5 //(feet) longitudinal, lateral, vertical distance from reference datum
fuel_flow_scalar= 0.29 //Fuel flow scalar
min_throttle_limit = 0.0 //Minimum percent throttle. Generally negative for turbine reverser

Engine location on the Extra 300;

[GeneralEngineData]
engine_type = 0 //0=Piston, 1=Jet, 2=None, 3=Helo-Turbine, 4=Rocket, 5=Turboprop
Engine.0 = 3.5, 0.0, 0.60 //(feet) longitudinal, lateral, vertical distance from reference datum
fuel_flow_scalar= 1.0 //Fuel flow scalar
min_throttle_limit = 0.0 //Minimum percent throttle. Generally negative for turbine reverser
 
I think at one point during my tries at raising up the engine location, I had the Y axis up to 2.0. All that did was get me down the runway with forward pitch, and boom... Prop strike again. I later changed it back to 0.5 on Y axis.

The Extra is a 6 foot diameter prop. I reduced mine to 5 feet. Made no difference. The dimensions are very similar.
 
Just a shot. Should there be a propellor.0 in there somewhere? to offset the prop from the datum?
 
According to the SDK docs static_pitch & static_cg_height are described as follows:

The static pitch of the aircraft when at rest on the ground (degrees). The program uses this value to position the aircraft at startup, in slew, and at any other time when the simulation is not actively running.

The static height of the aircraft when at rest on the ground (feet). The program uses this value to position the aircraft at startup, in slew, and at any other time when the simulation is not actively running.

Also for propeller.0:

This parameter allows for the propeller to be located at the specified offset (longitudinal, lateral and vertical) in feet from the engine that is driving it.

The above could be the problem? as suggested by ronh.
 
Bill, where do you have your reference_datum_position - is it 1.8, 0, 0 as in the Extra? It is the usual long-lat-vert sequence.

NB. Raising the engine two feet would be Engine.0 = 3.5, 0.0, 2.5 //(feet) longitudinal, lateral, vertical distance from reference datum

Seems propeller.0 is a relatively new setting, should work, too...
 
Last edited by a moderator:
As Manfred says. MS had a habit of placing the reference_datum_position at other than the FS center position (on centerline, 25% of MAC)
 
Many thanks guys for the input.

RonH wrote;
Just a shot. Should there be a propellor.0 in there somewhere? to offset the prop from the datum?
Click to expand...

RonH, the Extra didnt have a Propeller.0 coordinate and its rarely used. It was used mainly in the Kittyhawk as the engine was located in one local and two fans in other locals. They (Lockheed) broke this for a while, but brought it back. And it shouldnt be needed. The Extra didnt use it. (Thats my humble thoughts on it. I have very rarely ever seen it used).

mjahn said:
Bill, where do you have your reference_datum_position - is it 1.8, 0, 0 as in the Extra? It is the usual long-lat-vert sequence.

NB. Raising the engine two feet would be Engine.0 = 3.5, 0.0, 2.5 //(feet) longitudinal, lateral, vertical distance from reference datum

Seems propeller.0 is a relatively new setting, should work, too...
Click to expand...

Manfred,
I did raise it up to 2.5 on Y axis. It had a bad reaction and still had prop strike.
Datum;
reference_datum_position = 0, 0, 0 // (feet) distance from FlightSim Reference position: (1/4 chord, centerline, waterline)
empty_weight_CG_position = 0, 0, 0 // (feet) longitudinal, lateral, vertical distance from specified datum

Engine;
Engine.0 = 3.5, 0.0, 0.5 //(feet) longitudinal, lateral, vertical distance from reference datum

So the spinner is out there about 3.5 feet. I am going to bring it in to 2 feet and see what that does. I wonder if its too far forward...

Very very odd... Havent had this kind of thing happen before with a prop.
 
I moved the Prop (engine location) back to 2.0 feet from 3.5 feet out, and bing-baddah-boom! She doesnt hit the prop anymore.

WOOO HOOOOOOOOOO!!!

Just did some rough field touch and goes. No strikes. And this is a rough field. Big Andy; 7wa0 in ORBX, Washington. Roughest, tiniest strip this side of the Mississippi...

A thousand thanks guys. This had me good.
 
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