Virtavia A-4 Skyhawk, remains uncontrollable....

Navy Chief

Navy Chief

Senior Member
I know this subject has been brought up before, but I have a question. Cannot the flight model be fixed by anyone besides the developer? It just seems a waste of a beautiful model, not to be able to fly it. I have never been able take off without the aircraft becoming uncontrollable. I was reminded of this model when I saw a Blue Angels paint for it on Flightsim.to this morning. Go NAVAIR! NC
 

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Agreed. Hard to understand what Phil is thinking with this model. Visually, it is very nice, I think.
 
I agree with the both of you. And honestly, Virtavia isn't what Alphasim used to be.

Priller
 
I did a very quick test this morning. I actually avoided crashing, and I "think" with enough practice, I might be able to consistently take off without too much difficulty, but it is definitely a challenge. NC
 
I had posted a comment on the Blue Angel paint on Flightsim.to, and mentioned the difficulties on takeoff. The author of the paint replied back, saying the folliwing:

"I do believe the Virtavia is working on a flight model change to help with takeoff and landing! It may be released soon? In the meantime full stick back on takeoff (with 25% up trim) will keep you from tipping over--as soon as you hit about 85kts, the plane will begin to lift--just control laterally at that time. Landing is another story, I find it a victory if I can keep her on the runway without tipping over--but rarely can keep her on the center line!"
 
Years ago when the FSX version was still new, I felt that the Flight Dynamics File needed a great deal of work. At the time I was assisting John Cagle with the F-14X project in it's early development stages and he was trying to mentor me on Flight Dynamics File development when this very subject came up. I sent the A-4's FDE file to him to have a look at. As I recall, he noted there was a great deal missing or wrong in that FDE but in the end we didn't want to step on any toes updating the FDE and putting it out in public. I ended up doing the quick and dirty modification just for myself via the Flight Tuning section of the config file but it was what I would call considerably less than perfect when I finished it. Unfortunately we never re-visited it later and frankly, I would not know what/how to build a current external FDE. Dino's TA-4J is coming at some point and I'm sure it will be a good one.
 
I actually sent Phil a video of my attempted takeoffs a couple of weeks ago and he mentioned he had a control technique that kept it from jumping all over the runway, but it was evident that that technique wasn't an obvious one his customers were sharing. He theorizes that MSFS isn't properly simulating the delta wing's aerodynamics and the center of lift is moving back too early in the speed range, lifting the tail. He's investigating doing some changes to how the wing geometry is simulated to address this, and said he'll issue an update if he's able to improve it.
 
DennyA said:
I actually sent Phil a video of my attempted takeoffs a couple of weeks ago and he mentioned he had a control technique that kept it from jumping all over the runway, but it was evident that that technique wasn't an obvious one his customers were sharing. He theorizes that MSFS isn't properly simulating the delta wing's aerodynamics and the center of lift is moving back too early in the speed range, lifting the tail. He's investigating doing some changes to how the wing geometry is simulated to address this, and said he'll issue an update if he's able to improve it.
Click to expand...
Many thanks for the update, Denny😊
 
So given Phil's comment about a takeoff technique, I discovered I could take off successfully if I just kept the stick centered horizontally and pulled straight back into the pilot's stomach. Same thing on landing -- keep the stick pulled back until you slow down.

Not realistic, but if you want to actually fly the plane while you wait for an updated flight model, it at least worked for me. There was a little bit of side-to-side wobble as it lifted up, but nothing like the crazy jumping around the runway you get if you wait till you get to V2 to pull back on the stick.
 
Shame to read these comments. The Scooter was my favorite BA performance aircraft and I shall get this, but not until the issues are solved.

Cazzie
 
I did some work on it, awhile ago, but had to stop to work on other things. While being far from finished, the following changes can be made to improve the takeoff situation. Going from top to bottom,

Screenshot (2498).png
In order to closely match the chart,

empty_weight_CG_position = -0.3, 0, 0
CG_forward_limit = 0.16
CG_aft_limit = 0.29
station_load.0 = 200, 11.2, 0, 0.8, Pilot, 1

Change fuel tank positions
Center1 = 6.31,0,0.79,230,0
Center2 = -1.5, 0, -1.3,560,6

Correct Geometry
wing_area = 260
wing_span = 27.5
wing_dihedral = 2.41
wing_virtualdihedral = 0
wing_incidence = 0
oswald_efficiency_factor = 0.85
htail_area = 35.21
htail_incidence = 0
elevator_area = 11.33
rudder_area = 9.21

elevator_up_limit = 25
elevator_down_limit = 15
aileron_up_limit = 20
aileron_down_limit = 20
rudder_limit = 24

Replace the elevator trim limit with the following
;elevator_trim_limit = 20 ; Elevator trim max angle (absolute value) (DEGREES)
elevator_trim_up_limit = 12.25
elevator_trim_down_limit = 1
elevator_trim_neutral = 8


Based on glide performance, the drag coefficient can be determined
Screenshot (2497).png
The best glide for range occurs at Cl = 0.4, with ratio 9.9

In the aerodynamics section,
drag_coef_zero_lift = 0.0202

Set the lift slope for a symmetrical airfoil at 0 incidence, appropriate for the aspect ratio and sweep
lift_coef_aoa_table = -0.39:-0.88, 0.39:0.88

In the flight tuning section,
elevator_trim_effectiveness = 1.3

That's as far as I've gotten. Can't say when I'll be able to finish it, but hopefully soonish...
Testing the Lift/Drag ratio in the sim, it's pretty close at 10.1, vs the calculated 9.9
Screenshot (2513).png

Any performance discrepencies after this are due to engine/thrust and not drag.
 
Good news! There's an update on SimMarket with a number of improvements, including a new takeoff/landing model that makes handling a lot better. You still need to pay attention, especially in a crosswind, but it's worlds better now! I'll actually finally start flying this one.

Microsoft Flight Simulator 9_20_2024 12_30_49 PM_.jpg
 
DennyA said:
Good news! There's an update on SimMarket with a number of improvements, including a new takeoff/landing model that makes handling a lot better. You still need to pay attention, especially in a crosswind, but it's worlds better now! I'll actually finally start flying this one.

View attachment 156177
Click to expand...

Any feedback would be greatly appreciated. I reached out to Phil to assist a while back, as I wanted to see the Skyhawk flying properly in MSFS ( I own it too ) and help Virtavia get going on the Marketplace. They're almost there now. I did not contact any Skyhawk pilots for advice but I did use the actual manuals and interviews with them on You Tube etc to try to pin down the aerodynamics.


I suspect that Phil will continue on with this on his own now, but it's been great to work on the Scooter! :)
 
Well, my first attempt at takeoff was uncontrollable again. I've no doubt I am doing something wrong. Just not sure what. NC
 
DC1973 said:
I suspect that Phil will continue on with this on his own now, but it's been great to work on the Scooter! :)
Click to expand...
No chance for a DCD Scooter then, Dean ?.... ( will Virtavia's A-4 ever going to cut the mustard ???.... )

So what about a F4D Skyray, F3H-2 Demon, F-11 Tiger, F-7U Cutlass or FJ-4 Fury then, Dean ? All sea going you know, ready for some awesome 1950's/1960's MSFS2024 carrier operations ! :cool:

The're all extremely popular around here, mate, don't miss the boat on any of 'em ! :encouragement:
 
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