FLIGHT SHOP DESIGN TIPS & TRICKS

by Lars Kornstaedt

[ Back | Main Menu | Logout | Help ]

---

• Here is an advice for all users of FSFS outside the United States. I had this problem and it was solved with the help of Rush Mueller. When I applied textures to my planes they often did not cover all of the part I wanted to paint, got awfully distorted or were multiplied. When I chose 'Art Options' in the 'Parts List', no values or illegal ones were displayed. If you recognize these symptoms, the remedy is simple: just edit the Windows Setup Country Section: The comma is the thousands delimiter, the point the decimal point in the US and FSFS simply won't work correctly unless this is the default you defined. There is a patch that solves this problem for the ATC Workshop in the Forum.

• When texturing planes with FSFS you often loose a lot of time adjusting the exact position of your textures on the plane. It also often happens that they get highly distorted. This is most annoying with inscriptions. To avoid all these problems, just act according to this procedure suggested by Russell 'Rush' Mueller, SysOp of Lib5 of FSForum: In 'Aircraft Factory', go to 'Blueprint', choose the appropriate view angle and magnification and then choose 'Souvenir Shop' from the menu. Open your favourite paint program and paste the clipboard. You have now a picture of your project in the exact proportions of the a/c. All you have to do is to paint the livery on top of this image. It helps to mark the limits of the subsections around the plane before starting this. When you're finished, cut the individual parts from the full a/c picture and paste them into new images that you can then resize to the standard 256x128 format of Flight Shop. Although your texture might look very distorted now, it will fit your subsection perfectly. Copying, mirroring and pasting will finish the texture.

• It's important that the palette used to texture planes is the standard FS5.x palette. To be sure of this, just choose 'Photo Lab' from the 'Production Line' screen, choose 'AF5_STD.PCX' and press 'PAINT' to get to your paint program. Then, before doing anything else, save the palette. You can then load this palette whenever you think you might have changed it.

• Here's a tip from Terry Hill. He wanted the engine parts of his exceptional Lysander to look like shiny metal. It can be achieved by using the 'Gradient Fill Tool' of Corel Photo Paint with carefully selected grays. Don't try to use this on big parts, it will look awful.

FSFS does have a great number of bulkhead types at your disposition, but often these will not do the job. When it comes to building wing roots, wing boxes or complex cross sections like for the F-16, the Beluga or the Guppy, components are the only way to achieve a satisfying results. And they use less parts than similar structures.

When you start using components built from a multitude of handdrawn parts instead of structures, you may get frustrated at first: Parts simply do not appear in the model when you choose 'Smoothing', Components do not get textured.

Here are some basic principles:

• Components are textured *only* if they are smoothed.

• The parts you assemble into components should not have more than four points.

• The adjacent parts should always have common corner coordinates. Disregarding this principle results in joints that appear in the smoothed component or actual disappearance of these parts.

• To be sure that the components fit and the individual panels are perfectly placed, create an additional assembly that contains only the parts you are currently working on. (Suggestion by Mike Hill, Melbourne, Australia)

• Often, the crosssections you want to build are very similar to the bulkheads included in Flight Shop but are slightly modified in a certain area only. I always build a conventional structure first and then start to draw the parts starting from this 'template', changing it where necessary.

• To be sure that the individual panels fit well, I start at one point of the a/c and modify the first part over and over again, always keeping one edge unchanged.

• It is important to keep control over things, so you should always use a systematic numbering of the individual panels. I call my parts B_PNL_56 or suchlike: Body Panel Number 56. Parts are usually numbered starting from the top right of the fuselage and wrapping around the fuselage by the cross section, starting at the rear and going forward.

As I have previously stated in a letter to MICRO SIMULATEUR, flight dynamics definition is a black art and to get any result, it is best to have some tips from people with more experiance. What little I know has been inspired by several people, but without Mike Hill I would probably have given up a long time ago.

Here is my small contribution to your successful flight model definition:

• It is always a good idea to start with the flight model of a plane that is similar to the one you have built. You can get these from several sources, I prefer FSForum.

• To be sure to get a unique result that fits the specific plane you want to render, try to start with the real life values you can get your hands on. These would be the dimensions, weight and stall speeds of the real a/c.

Next, I will state a short definition for each available parameter along with an analysis on it's effect on the flight model.

• Configuration: Wingspan. The wingspan is measured between the wingtips. Increase causes more lift, greater stability and increased drag.

• C: Aspect Ratio. The aspect ratio defines wing efficiency. Increasing this value *decreases* lift and drag.

• C: Wing distance from CofG. This value has a foundamental impact on stability and manouverability. CofG should be in front of the wings lift center or exactly in it for a manouverable aircraft. a backward position destabilizes the plane.

• C: Wing Dihedral. The dihedral is the angle between wing center line and the horizon. A big dihedral causes the plane to automatically roll out of a curve. This tends to be coupled to strange yawing in FS5, so I always try to minimize this value. If there is a stability problem in this regard, it's often better to increase the dihedral scalar.

• C: Horizontal tail distance from CofG, surface area and span. Distance between CofG and center of lift of horizontal stabilizer. The bigger these values, the bigger the pitch stability.

• C: Vertical tail distance from CofG and surface area. Increase in these values increases yaw stability.

• Weight and Balance: Empty Weight and Fuel Tanks: These should be real world values. Specific fuel consumption can be specified in the Engine menu to get the appropriate range.

• W&B: Moments of Inertia. These define the force that opposes itself against any change in aircraft position. They have to be specified around the individual axis. FSFS fixes them using the visual model as a reference in a way that remain cryptic to me. It achieves quite sensible values most of the time. I use these to adjust flight characteristics. The yaw moment is usually too small. FS5 planes tend to slide in curves. Don't be afraid to make drastic changes here. Remember that any change here will be reset when the plane is remanufactured from the FSFS Production menu.

• Engines: number of engines, max power and engine high RPM. These I set acording to the real world plane. Slight adjustments can be made to get specified max speed etc, but it is always preferable to modify aerodynamic values to get the desired results. FS5 prop engines are no Turboprops. All loose too much power at altitude and there is nothing you can do about that...

• E: Prop diameter. Choose the real world value as a reference, but remember that differing prop profiles remain unaccounted for. Corrections are allowed in this department.

• E: Oil temperature & pressure scalar, EGT. Any hint on these is welcome...

• E: Engine position. Try to choose real life values (for recip. planes: prop spinner position). This is not always possible. FSFS does not like rear props (comment from Ed Ziegler). Planes tend to yaw dangerously with excentric engines...

• Aerodynamics: Max Mach. This triggers the 'Overspeed' warning. This is easy to calculate from the max. speed at a certain altitude, typically 6000ft, you will probably find in the data-sheet of the real world a/c. Mach number is a/c speed devided by speed of sound at that altitude. This can be looked up in the standard athmosphere. Speed of sound at 6000ft: approx 332m/s=1089 ft/s.

• A: Zero flaps stall and full flaps stall. These values do not only trigger stall warning. The difference between these values defines the flap efficiency. The bigger the difference, the more lift they cause. I like to keep this difference low (3-8 knots) since you can get strong floating on final and thus yaw on final approach. The effect of the absolute values for these two characteristics escape me.

• A: Induced drag scalar. Drag is calculated from zero lift drag + induced drag scalar multiplied by lift squared. Lift increases with speed and angle of attack. Keep this in mind when you specify this value. It has a great impackt on accelleration and max speed.

• A: Spoiler, Gear and flaps drag scalars. These apply when the appropriate device is extended. Spoiler drag can be used to simulate airliners spoilers (relatively low value), airbrakes on fighters (high value) or arrestor hook on carrier a/c (gigantic value). Flaps should cause some drag but it should not be overdone. Gear drag can be defined quite high if your plane tends to float on final approach. Selecting big values here will make speed bleed of quickly and you might have to add some throttle on final approach, but that's ok.

• A: Flap and gear moment. Usually, extended flaps and gear cause a positive pitch moment. Tuning this too finely is wasted effort.

• A: Scalars. All the following values are used to make a correction in departments that seem to be already defined by the absolute values (eg: wing dihedral by dihedral value in the Configuration menu) but strangely enough, it's not the same to change that dihedral value from 1 to 2 degrees versus changing dihedral scalar to 2. Generally the scalars in this menu allow finer tuning. Changing the absolute values in other menues should be prefered to changing these.

• A: Dihedral scalar. Increases roll and yaw stability. Should not be pushed too far since high values alter curve flying in a negative way (drifting, slow turn rates, starnge yawing).

• A: Elevator, aileron and rudder scalar. These allow to increase the reaction of the a/c to control surface input. Never mind these reaction when tuning the stability of your plane (which you ahould always start with), you can (nearly) always tune manouverability with these scalars.

• A: Pitch, roll and yaw scalars. These adjust stability around the respective axis. Very important for manouverability tuning.

• Gear and Scrape menu. All the values in this department FSFS defines from your visual model data (footprint definition in particular) and no change is typically necessary here. If your plane suffers from taxiing problems or landing roll instability (see below: 'Ringelpietz'), you might want to move the main gear scrape back or increase wheel track. You should always prefer editing the footprint and CofG position (which is most often the real reason for this behaviour) since the values in this section are all reset when the plane is reproduced from the Aircraft Factory according to footprint information.

Next thing to do is have a test flight! The problems you will encounter most often on these are stated below, along with a suggestion for the remedy.

• The a/c crashes on the runway a soon as you choose it from the menu. This is quite bad, but no reason to panic: the inertia moments are too small and the center of gravity at a bad position, typically too far forward. This should happen to 'tail wheel planes' only.

• The a/c reacts much to strongly to control inputs. If this is the case, you will have to increase the value for the inertia around the appropriate axis in the weight and balance menu and/or the stability scalar in the aerodynamics menu. Another possibility is to decrease control surface scalars, but this should only be used for fine tuning.

• The a/c does not fly in a stable way, that means: slightest control inputs cause the plane to stall/ enter a deadly spin... In that case, several things can be done. The values for the dimensions, especially wing and stabilizers, should not be considered sacred. Real world aircraft use a multitude of wing profiles. The properties of these are not considered in any way by FSFS unless you define the way they influence flight dynamics by altering the available values. Deadly spins often can be get rid of by increasing wing span, but remember that wing span increase does also mean more drag and thus slower maximum speeds.

• The a/c is not manouverable enough. Decrease inertia moments, stability scalars, increase control surface scalars around the appropriate axis.

• The a/c stalls much too early, speed bleeds of fast in tight, pulled turn and loops. Decrease pitch inertia.

• Full aileron deflection followed by stick release (quick movement in opposite direction) causes the a/c to enter a roll that can not be recovered. This behaviour is often coupled to counterrotation or roll blocking at sudden full aileron deflection. That's a bad one. No readily available quick solutions for it. You will have to prepare for a long evening and a lot of experimenting. Try increasing both the roll inertia and aileron scalar in proportion. This should conserve roll rate while increasing stability and get rid of the 'deadly roll' problem. Roll scalar should be used for fine tuning.

• The a/c 'floats' on final approach/with full flaps. Decrease difference between full and zero flaps stall, decrease absolute values for these settings. Increase gear drag.

[ Back | Main Menu | Logout | Help ]

---

Thanks to Lars Kornstaedt for permission to use this document. You can visit his personal home page at http://ourworld.compuserve.com/homepages/L_Kornstaedt.