Conspicuous by Their Absence - Page 35
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Thread: Conspicuous by Their Absence

  1. #851
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    a couple posts to reply to;

    your old man's disease comment made me smile.
    it's too true, and it's not just a guy thing,
    although, it seems our cases are much more acute.
    heck, come to think about it, i've always had it.
    at least, as far back as i can remember.

    about the knife edge maneuver;
    never tried it, but, most likely, will. shortly
    have you tried it in a jet?

    granted, pilot skill is essential, but,
    controller sensitivity (or lack there of) comes to mind.
    for example, go into settings, game controllers... properties.
    does the + in the X Axis/ Y Axis window bounce around a bit?
    how about the rudder Axis? does it bounce?
    and notice that the axis' move when you simply
    put your hand on the controller.

    another control issue i find aggravating;
    is it just me, or does anyone else find
    it difficult to just fly straight and level?
    it doesn't seem to matter what i'm flying,
    although, some aircraft are better than others.
    when i attempt to trim, either left/right or up/down,
    i can never get it just right. or should i say, correct.
    i can get it trimmed close, but,
    it always seems to drift one way or the other
    and one tap of the trim key usually sends it
    in the opposite direction...never centered.

    another interesting little quirk i've noticed is,
    if i get it trimmed close to straight and level,
    sometimes, the trim setting is lost if i maneuver
    using the rudder, elevator or ailerons.
    then, i have to do the trim process again from scratch.

    in the end, the only way i can fly straight
    and level is to turn on the auto pilot
    which doesn't seem very realistic to me.

    dang...there was one more comment i wanted to make,
    but, i forgot what it was.



    THERE IT IS! i remember, now

    i know the excitement of the kill has an effect,
    but, my aircraft seems to move all over the place
    when approaching a potential victim.
    for some reason, i can not keep my aircraft stable for the shot.
    the slightest controller movement seems to over compensate
    and i invariably loose my position on the target.
    and yes, i have tried backing off the controller axis' sensitivities.
    i've even tried using the keyboard
    instead of a controller button to fire the guns.
    that helps a bit, but doesn't solve the problem.

    bottom line, is it an inadequacy of the old sim,
    a controller issue, pilot error, or possibly,
    a combination of all these factors?
    sometimes the magic works.
    sometimes it doesn't.

  2. #852

    Where Do I Start?

    Hi Smilo,

    We're pretty much in agreement regarding the distraction issues. I have had them since I was young also, but have also worked my way around them to get a few things accomplished. With this hobby, I choose NOT to work around them because it is just a hobby and my goal is to explore and learn. If somethinng releasable comes of it, great. If not, oh well....

    Regarding the other subjects, I think you just opened a HUGE can of worms here....

    First of all, Dunno about Jets. I don't think I have but a couple installed.
    I trust none of the flight models except for perhaps the Learjet and I don't think that one will fly a knife edge safely.

    The rest of this is my own opinions but with a little bit of background to back it up:
    First of all, the controller is less important in my opinion.
    It is really nice if it centers nicely and doesn't wobble around without user input, but REAL aircraft control columns don't have spring loaded centering. Centering is aerodynamic and weight balancing for the most part and it isn't all that precise.
    If you are really curious, look for "Stick-Free" and "Stick-Fixed" stability in flight reports. What we have in the sims is only Stick-Fixed. There really isn't any feedback, even on the force-feedback joysticks because the folks coding the forces there generally have no clue what they are really doing.

    Regarding aircraft stability, the best single engine fighters are either neutrally stable or barely stable on each axis.

    An example of longitudinal instability is the Spitfire. In order to cure it, they enlarged the aerodynamic balance after about the Mk.V. It made the elevator much too sensitive but made the aircraft barely stable longitudinally. I have read some of the engineering docs on this subject and don't really understand HOW it worked, but obviously it did.

    The FW 190A pilot report states that the aeroplane had ideal stability for a fighter with neutral lateral stability (and a very high roll rate), low stability longitudinally and good stability directionally.

    The P-51 Bubble Top fighters were barely stable directionally to the point where you could bend the aeroplane if you applied a lot of rudder at high speed. The designers attempted to cure the issue first with a fin fillet on the lateer D and K models and eventually pretty much cured the problem with a taller fin and rudder on the H model.

    If you load an aircraft with the CoG very far aft, longitudinal stability gets to be quite poor.
    (You also get better performance though.)

    Regarding Trim:
    Most CFS aircraft have trim notches that are way too coarse. it allows for greater compensation for damage, but doesn't allow for very precise trim to allow the aeroplane to fly hands-off.
    I generally start (when starting with the stock P-51D) by setting the Longitudinal (elevator) trim to about 0.400 instead of the stock value of 0.500. To be honest, this doesn't make all that much of a difference.
    I then reset the Lateral and Directional trim down to 0.015 or so which is much less than the original.

    Most real aircraft will have pretty large trim changes with changing weight conditions such as burning off fuel or with changing airspeeds. The Me 109E has its fuel tank behind the pilot and trim goes nose down pretty quick as fuel is burned off. The P-40 changed directional trim pretty seriously depending on airspeed. The Hellcat (and most other aircraft) changed longitudinal trim with airspeed.

    With just about all my aircraft projects over the last few years, I test that the aircraft can be trimmed to hold a compass heading at fully (non-WEP) power at fairly low altitude (around 5000 feet) for at least a couple minutes. Longitudinal trim is generally set to be slightly nose up because I found that this changes a bit with altitude. I usually have a test sheet showing the settings I used and in very recent releases have put that information into the aircraft checklist.
    The way I do this is to count trim notches and see what comes closest. If I get an "in-between" value, I adjust the trim notches so that I can hit the proper value.
    This method works reliably but is incredibly tedious to do.
    Often there are multiple combinations of Lateral and Directional trim that will maintain a compass heading.
    It also needs redone if the level speed or weights & balance change.
    I doubt that most developers take the time to check aircraft trim settings which is probably why you may find aircraft that won't trim to fly straight and level.

    I usually set the CoG fairly far aft as mentioned earlier with the center of lift an inch or two ahead of the Center of Gravity. This also has a tendency to make the aircraft harder to trim longitudinally and often leads to a long period oscillation (phugoid). This is one part I am still experimenting with.

    I believe the problem with trimming in the middle of a fight is that your speed and attitude changes are so quick that you never have a chance to let things setting down to see what the actual result was. Also, as stated earlier, trim usually varies with airspeed, so unless you maintain a constant airspeed, you should expect trim changes.

    This is my current view of the world and easily subject to change as I learn more.
    Hope this makes sense.
    - Ivan.

  3. #853

    Ground Adjustable Trim

    Most aircraft that I know of have Longitudinal (Elevator) trim that can be adjusted in flight

    Many aircraft have Directional (Rudder) and Lateral (Aileron) trim that can only be adjusted on the ground.
    Typically this is done by bending a small flexible tab that is attached to the trailing edge of the control surface.
    Normally this would be done as part of production test flying and then adjusted as needed in service.

    On aircraft with only ground adjustable trim, does it make sense to eliminate the trim settings?
    I generally don't do that because I don't know of a way to "preset" trim in the AIR file.
    Longitudinal trim is easy to preset.
    Do any of you know of a way to adjust directional or lateral trim in the AIR file?

    - Ivan.

  4. #854
    Here are a few screenshots from some experimentation with the P-38J by Eric Johnson.
    The original AFX that I have does not have Propellers, Flaps, or a transparent Canopy.
    I added those and a few other features to experiment with the best assembly method for a potential future project.

    Eric Johnson did extremely well with the overall dimensions of his project. So far, I have found only one major dimensional issue and visually the issue is not obvious. The general shape is pretty good considering he was limited to 0.10 foot increments and used 8 sided cross sections.

    - Ivan.
    Attached Thumbnails Attached Thumbnails P38J-EJ0.jpg   P38J-EJ1.jpg   P38J-EJ2.jpg  

  5. #855
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    thanks for your replies on the subject of trim.
    although, i am a "little" confused.
    at least now, i know trimming issues
    are not entirely pilot error.

    in the first post, you talked about how you set up trim
    when starting with a stock p-51 air file.

    then, in the next post, you ask if anyone knows
    how to "adjust directional or lateral trim in the AIR file?"
    sorry, i don't know how to do that sort of thing,
    i leave air files to the experts.

    is it not possible to make an aircraft fly straight,
    or at least straighter?
    i maybe mistaken, probably am, but,
    isn't the directional and lateral, for want of a better word, drifting
    caused, for the most part, by the propeller P factor?
    if so, couldn't one simulate directional ground trimming
    by reducing the P factor in the air file?

    you're right, this is a can o worms

    replying to the p-38 post;

    that's not a bad looking p-38.
    it's amazing how a transparent canopy
    and props improve the visual model.

    to bad the cross sections are only 8 sided.
    12 or, better yet, 16 sides would really smooth the curves.

    as is, it would make a suitable replacement
    for the stock p-38, especially if it's bleed free.
    sometimes the magic works.
    sometimes it doesn't.

  6. #856

    Setting Up Aircraft Trim

    Hi Smilo,

    The first post was about using the P-51D AIR file was just describing how the size of each notch of trim adjustment was way too high to allow precise adjustment of Lateral and Directional Trim. One setting might be putting the aeroplane's left wing down while one notch to the right puts the other wing down. What you need is a half notch of trim or just smaller changes per notch.

    It is sort of like the case a couple decades ago when a fellow decided to bring his Ruger Mini-14 to the 200 yard firing line during High Power (Service Rifle) practice. I was in the group pulling targets at the time. One shot would go left of the bull and the next would go right. I found out later that his sights were only capable of 2 MOA adjustments, so one click would move the aiming point 4 inches. The surprising thing was that he was so consistent with his aiming and even more surprising was that his rifle was so accurate.

    The second post was about setting up default trim. By changing the angle of incidence of the stabiliser and a few other things, I can easily make the aeroplane be tail heavy or nose heavy without any user adjustments. The question is whether or not there is a way to make the aeroplane fly with the right wing down by default without changing other things that should not be changed. Is there a way to make the aeroplane yaw to the right without any user adjustments of trim?
    There is often an aerodynamic twist built into an airframe to adjust for the asymmetrical airflow of the propeller.

    There are a few other factors besides P-factor that cause a drift. P-factor for the most part only affects the aircraft on the ground because the direction of travel is not the same as the propeller axis. In the air there are a bunch of other factors that affect things. I don't know of a nice way of adjusting those factors without causing some other side effects.

    The BV 141 was a pretty good illustration of one method of adjusting for the asymmetrical propeller effects. I am using pretty much the same idea on the flight model for the P-38J at the moment and it DOES work for the most part. Yet there are still some significant side effects.
    With the P-38J, the engine thrust centerlines are about even vertically with the aircraft centerline (by my definition) and are offset 96 inches laterally from the centerline. I found that if I put the Port Engine out to -120 or -121 inches, most of the propeller direction effects are cancelled out pretty well. There is still a slight pull TO THE RIGHT on take-off and a slight drift to the left at high speed cruise, but it isn't hard to manage. I am still wondering if a vertical offset would do anything useful.

    - Ivan.

  7. #857
    Quote Originally Posted by smilo View Post
    replying to the p-38 post;

    that's not a bad looking p-38.
    it's amazing how a transparent canopy
    and props improve the visual model.

    to bad the cross sections are only 8 sided.
    12 or, better yet, 16 sides would really smooth the curves.

    as is, it would make a suitable replacement
    for the stock p-38, especially if it's bleed free.
    Thanks Smilo.

    Actually there are a lot of little changes in shapes that are not apparent from those screenshots. I have taken out a mess of bleeds so far and plan on fixing a bunch more. The things that are still bothering me are the coolant radiators on the booms and, the shape of the rudder, and some bleeds out the front that the wing-fuselage templates don't seem to be fixing.

    I believe Eric Johnson really did very well with just 8 sided cross sections. I normally use 12 sided cross sections and run out of resources with a single engine fighter. I don't believe it is possible using AF99 to build anything signifcant using 16 sided cross sections.

    My plan is actually NOT to release this one at all. I am taking way too many shortcuts that have my shop foreman cursing under his breath. notice the cockpit is still empty? Even my own pilot refuses to be seen flying it! I am messing with it to test assembly sequence and general construction techniques. It is also better than any other P-38 visual model that I have found for testing and building a flight model. (So, the pilot is still doing the test flying, but using his invisible man Halloween costume.)

    I WILL send you a copy to use as a replacement for the stocker though my plans are not for public release.

    Womble55,
    Hopefully you are also following this thread because the screenshots attached are an example of the method I was proposing in an earlier discussion about Fowler Flaps. All of the Flap parts and Flap Well are set in the "Retracted" positiion in AF99. Aircraft Animator finds them and sets the axis of rotation as one might for a simple hinged Flap.
    I then move the axis DOWN and AFT.
    The amount Down sets how far BACK the deployed Flap will be.
    The amount Aft is pretty much how far UP the deployed Flap will be.
    It is interesting to mess with the pieces in Aircraft Animator.
    For some reason Fowler_2 won't upload but you can still get the idea....

    I also had a lot of muttering and cursing when I figured out that the outer Wing section where the outboard Flaps were mounted was actually added to the assembly with "Dihedral" selected. It makes the default Component not useful as a reference to use in building pieces. That is why I have never used it after seeing the result in a Kawanishi N1K2-J Shiden KAI that was my first AF99 attempt.

    - Ivan.
    Attached Thumbnails Attached Thumbnails Fowler_0.jpg   Fowler_1.jpg   Fowler_3.jpg   Fowler_4.jpg  

  8. #858
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    yes, please.
    i would welcome a copy of your upgraded EJ p-38j.
    an upgraded afx would, also, be very cool.

    from your past comments, i am aware of af99 resource limitations.
    (i do remember some things)
    my 12-16 side comment was merely a wish list.
    for one to build with that kind of "accuracy", ad2k is a must.

    i have uploaded the EJ p-38 afx into my ad2k install
    and played with it a little.

    i am tempted to pursue the project,
    but, knowing my MO, i will, for now, refrain.
    i have another long term project,
    that i don't want to interrupt....again.


    quick question, what does MOA mean?
    sometimes the magic works.
    sometimes it doesn't.

  9. #859
    MOA is short for Minute of Angle. 60 Minutes in 1 Degree.
    A Minute of Angle subtends approx 1.04 inches at 100 yards.
    In the field of shooting, it is used as a measurement of accuracy to describe the angular dispersion of shots fired.
    For shooting, 1 MOA is typically assumed to be 1 inch at 100 yards instead of 1.04 inch.

    1 MOA for whatever reason (Probably because it is not that hard to achieve) is often used to describe an "Accurate" rifle.
    The idea is that the two shots are measured (at the center of the bullet hole) and the number is recorded.
    The problem is that there isn't any great standard as to how many shots are fired which makes comparisons quite difficult.
    Often Hunting rifles fire 3 shot groups for record because they tend to have lighter weight barrels which heat up quite fast with firing and the point of impact may move when the barrel is hot.
    Service Rifle (a competition category using US Military rifles) typically describes 10 shot groups.

    I typically shot 5 shot groups and often superimpose the resulting groups to get an impression of what a 10 shot group would have been. In general, this SHOULD give a slightly worse result than a single 10 shot group would have because the conditions may have changed slightly between groups.

    A typical US Military rifle (M1 Garand and later) has adjustments that move the Point of Impact 1 inch per "click". A service rifle with competion sights typically has sights that move the POI 1/2 inch per click. I don't shoot well enough without a telescope to take advantage of that kind of precision.
    That was the surprising part of this story. They fellow with the Mini-14 was holding a group that was about as well as the rifle could achieve in my experience. His sights did not have fine enough adjustments to let him center the group on the target.

    - Ivan.

  10. #860
    That brings back a few memories.
    When I was shooting full bore in the Air Cadets, we used service .303 Lee Enfields and fired a good 100 rounds per rifle in a day.
    They were just as accurate in the afternoon as they were in the morning and our marksmanship was still 2.5 inch at 300 yds, not bad for 14 to 17 year olds.
    All this with a blade and aperture sights.
    We once had a Bren, 30 cadets + 28 rounds apiece and the barrel soon heated up. Solved by unclipping the barrel and dropping it into a bucket of water while the spare barrel was clipped on.
    I tried but could not get on with the 7.62 SLR, it didn't seem to have the build quality that the Lee Enfield had, even though the round it used had a higher muzzle velocity.

  11. #861
    Quote Originally Posted by Ivan View Post
    The idea is that the two shots are measured (at the center of the bullet hole) and the number is recorded.
    Perhaps I should have phrased this differently. I seem to have left out a few words.
    In the group, the two shots FURTHEST APART are measured.....

    Hello Womble55,

    I also have a fair amount of experience with Lee Enfields and have owned a few. I have never gotten sub-MOA accuracy out of any of them though the No.4 Mk.I* and a No.1 Mk.III* have been pretty respectable with 1.25 inch groups for 5 shots at 100 yards. The FAL was pretty comparable with good ammunition though there were hints it might do better but the scope mount and front sling swivel didn't look conducive to accuracy.

    If your guys were hitting well under 1 MOA at 300 yards with iron sights, you should have come over to this side of the pond and shot at the National Matches at Camp Perry. Consistent groups of that kind are enough to shoot clean scores and win the matches with a pretty high X count as well.
    My own scores are not nearly so good. At Prone and Sitting, I was getting scores in the Mid 90s and for Offhand, I was typically getting scores only in the 70s. I wasn't anywhere near steady at standing.

    - Ivan.

  12. #862
    We only ever shot prone and the grouping was after many attempts at the RAF marksman badge, shamefully I only ever did it the once as that was enough to get the badge and requalification wasn't required.
    I loved the Lee Enfield, it looked right, felt right and because of the years of care smelt right.
    We only ever used standard military issue rounds, no special preparation or anything like that. We were typically given two five round clips, loaded the magazine and shot.
    If we were trying for our marksmanship badges we would have a spotter and advice from a senior NCO or Officer during the day and could fire up to fifty rounds a day.
    I believe my hearing problems nowadays is because of the number of rounds fired without ear protection....Happy Days EH?
    Lets get back to the subject in hand and what we would like to see in CFS1

  13. #863

    Lee Enfield

    I kinda like Lee Enfields. They were my first "High Power" (in American, this means centerfire) rifles.
    Decades ago, they were inexpensive and plentiful. .303 British isn't the easiest cartridge to reload though.

    Now on to the CFS Part:
    I can't seem to pin down why the last P-38 Flight Model I did back around 2000 or 2001 has a pretty consistent engine failure.
    So, instead of tuning the old version, I thought it would be a good idea to build a new one. Perhaps I will do a comparison later.

    So far, the results are that HP is about right for Sea Level and Critical Altitude.
    Between that, the numbers are pretty far off.

    Performance is:
    1415 HP @ 500 ft for 340 mph.
    1477 HP @ 25,000 ft for 422 mph.
    Maximum speed is actually 428 mph @ 22,500 ft.
    Service Ceiling with 1/2 fuel is pretty near 41,000 ft.

    There is plenty more to tune after that.

    - Ivan.

  14. #864
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    Re: Lee-Enfield

    George MacDonald Fraser (of "Flashman" fame) penned a wonderful segment in his WWII memoir, "Quartered Safe Out Here". He served with the Border Regiment in Burma in 1945 and carried a Mk III 'til he made Lance-Corporal and had to carry a Thompson. It's an excellent read loaded with his trademark snarky humor.

    Steve
    AAF Lament:

    "Glory! No more regulations!
    Rip them down at every station!
    Ground the guy that tries to make one!
    And LET US FLY LIKE HELL!"

    From "There I Was...Flat On My Back" by Bob Stevens

    Tune: Battle Hymn of the Republic

  15. #865

    Long Live the Short, Magazine, Lee-Enfield!

    Hello Wayland,

    The SMLE or No.1 Mk.III is one I know pretty well.
    I just came across a box of spare parts for the No.1 Mk.III* last week.
    I had bought three brand new bolt bodies made for the Australian guns, several bolt heads and other assorted parts in attempt to fit a new barrel.
    The pieces came from all over but I did find a combination that fit together with perfect headspace which nearly impossible to find in a service Lee Enfield.
    I also had two unused brand new bolt bodies, firing pins, extra bolt heads and some other left over pieces which I just put in a box and left on a shelf afterwards.

    - Ivan.

  16. #866

    Conspicuous by Their Absence

    Some Aircraft seem to be much easier to fly than others when doing low level high speed passes. One of the nice things about opposite rotation of the engines is that there is no noticeable lateral or directional trim changes. There is also quite a lot more acceleration.

    Did lots more tuning on the P-38J. Some of these edits were quite radical and I am still not all that close to final yet.

    One of the funniest things I encountered was braking too hard and flipping (!) the aeroplane.
    That wasn't hard to fix, but it was an interesting surprise to flip an aeroplane with a nose wheel.

    The Flight model I was working on had three fuel tanks per side:
    A 90 Gallon Main Tank behind the main spar of the wing.
    A 60 Gallon Reserve Tank ahead of the main spar.
    A 55 Gallon Tank in the leading edge of each wing outboard of the engines.

    I came across an earlier version of the AIR file (from about 2000 or so) and noted that the model I was trying to build was a P-38J-10.

    The early models of the P-38, without the chin scoops, had their intercoolers built into the outboard leading edge of each wing.
    This was quite an inefficient setup with the supercharger in the middle of each boom piping charge air out to the wing tips before it went into the engine.
    The leading edge intercoolers were efficient for streamlining, but also didn't cool the air that well before it went into the engine. This was the main limitation to running the engines at higher power settings before detonation would start.
    With the J model, the intercoolers were moved under the engines next to the oil coolers. That greatly increased the maximum speed because although the airframe drag was higher, the engine power was much higher.

    At some point, fuel tanks were installed where the intercoolers were, but those fuel tanks were not present in the J-10 model.

    Another feature that was not present in the early J models was the dive brake under each wing to aid recovery in a high speed dive. In trying to add in some compressibility effects, I tried quite a few high speed dives starting from around 35000 feet altitude. Many of them ended up as crashes because elevator effectiveness at very high speeds is greatly reduced and the P-38 gains speed in a dive VERY quickly and ghe maximum diving speed is very low. In fact the limit (460 mph IAS at low altitude) is about the same as for a late model Japanese Zero but for very different reasons. (At high altitude it is only 420 mph IAS.)

    This is one of the parts I really like about flight sims: Reading about compressibility effects and dive limitations is interesting, but actually "experiencing" and being able to experiment with the effects gives a much better appreciation of how things worked.
    Perhaps this is a bit circular because we try to program in the documented behaviour and then test for the same behaviour.

    Current Performance:
    1417 HP @ 500 ft for 344 mph
    1477 HP @ 25,000 ft for 421 mph
    Actual Maximum speed is 427 mph @ 22,500 ft
    Service Ceiling was not tested but should be considerably higher with a bit more engine power and less fuel.

    Lots more left to tune. Hopefully I can figure some of it out.

    - Ivan.
    Attached Thumbnails Attached Thumbnails P-38EJ_LowPass1.jpg  

  17. #867

    Braking Factor

    Sometimes something sits right before your eyes and has hints that it might not be what people tell you it is....
    (Advance Warning: I am gonna get VERY long-winded here.)

    The Background:
    A few days ago, I was very surprised when I came in for a rather hot landing in the P-38J.
    I had lined it up after wobbling all over the place and finally had it centered on the runway.
    When I applied brakes, the aeroplane flipped. Imagine my surprise at having a nosewheel aeroplane flip!

    That is not sposta happen, but the P-38 is an interesting combination:
    It has a fair amount of weight on the nosewheel unlike most aeroplanes with a tricycle gear.
    It also has a CoG that is fairly high: Almost even with the Engine Thrust Line which is where I set it for thie visual model and AIR File.

    Fixing it was pretty easy.
    The Braking Factor is a 16 bit Integer as described in both AirEd and FDE config files.
    Maximum value is 32,767 and Minimum value would be -32768.

    I have entries in my notebook from testing many years ago that Positive values seem to prevent the aeroplane from planting its nose into the runway when braking too harshly.

    I had therefore made it a habit to use negative values so that if the pilot goofed, it aeroplane would oblige by sitting on its propeller. I also had noted that there didn't seem to be much variation when using negative values, but that very low negative values had too harsh braking and would flip too easily.

    I reset the P-38J's brakes to a reasonable positive number that reduced speed pretty well but didn't cause the aeroplane to "hop" much when slowing down.

    This Evening's Events:
    Since I am working on a P-38J AIR File and do testing and archiving on several different machines, I can seriously alter the AIR file on my test machine without regard for accidentally damaging my working copy of any particular AIR File.
    The P-38J was the perfect subject for testing because it does not pull to either side on the take-off run.
    It will track straight under full power acceleration unlike any other CFS aircraft I have encountered.

    I was not satisfield with what I had in my notes from earlier testing of negative values; They seemed way too similar.
    I needed to be able to test full braking to quantify it but without being able to flip the aeroplane.
    First corruption of the AIR file was to move the nosewheel contact point from 100 inches ahead of the CoG to 200 inches ahead.
    The aeroplane pitched a bit on the take-off run but was controllable otherwise. It also no longer flipped.

    First test was to see what effect the positive values actually had and do it in such a way that I could quantify it in my notebook.
    It could be seen fairly quickly that low values had nearly no effect and high values braked faster but cause the aeroplane to hop.
    From 0 - 32,767, I had already chosen to use 22.000 for fairly good braking but with very little hopping.
    Results were as expected and very predictable though I won't claim that the effect is linear. There is a much greater observable difference between 500 and 10,000 than between 22,000 and 32,767.

    Second test was for negative values. The extremes at -1 and -32,768 all seemed too harsh with the wheels hopping but neither value would flip the aeroplane thanks to my extended nose wheel.
    -1 seemed to brake quicker but I could not tell by how much.

    Next step was to remove as much subjectivity as possible from the testing.
    This was made much easier by an aeroplane that had no tendency to crab or pull to either side on take-off.
    The test protocol was the following:
    1. Load Aeroplane into simulator.
    2. Start Engines and go to Chase view.
    3. Set the Speed Display at the top of the screen.

    4. Use Full Engine Power for acceleration until Aeroplane reaches 95 knots.
    5. Bring Engines to Idle.
    6. Apply Full Brakes when Speed drops to 90 knots while starting Timer.
    7. Stop Timer when Speed drops to Zero.

    Here is where things get interesting:
    Braking Factor of -32768 went from 90 to 0 in 11.31 Seconds
    Braking Factor of -1 went from 90 to 0 in 6.56 Seconds

    OK, So far, so good, but I was a bit disappointed that the Negative values that allowed a flip didn't allow as much control as the Positive values.
    I figured that as long as I had a working protocol, I should also see how the Positive values compared.
    There was no point in testing the value for Braking Factor Zero since it was pretty much no Brakes at all.

    Ready for this?

    Braking Factor of +32767 went from 90 to 0 in.... 11.31 Seconds

    Hey! Wait a minute!

    If the greatest Positive Braking Factor is only equal to the weakest Negative Braking Factor is there something here we are not seeing? This is where I started seeing a lot of Neon signs lighting up.

    Here is a little explanation on the most common way that computers represent SIGNED Integers in Binary:
    (Skip if you already know this.)

    Zero is simple in a 16 bit number (Extra Spaces added for Clarity.) (I am representing this as a Big Endian)
    0 000 0000 0000 0000

    One is (Just add 1 to Zero)
    0 000 0000 0000 0001

    Negative One is (Just Subtract 1 from Zero) (Note that the first bit here is the sign bit: 0 for Positive, 1 for Negative.)
    1 111 1111 1111 1111

    The Largest Integer 32767 is
    0 111 1111 1111 1111

    The Lowest Negative Integer -32768 is
    1 000 0000 0000 0000

    Now if we still have a 16 big number but treat it as an UNSIGNED Integer, we can only represent numbers from Zero to 65535.
    If we use the same bit patterns we had earlier:
    What we thought was Zero remains Zero.
    What we thought was 32767 remains 32767.
    What we thought was Negative 32768 now becomes Positive 32768 which is pretty close to 32767.
    What we thought was Negative 1 now becomes Positive 65535.

    What this leads me to believe is that the value we thought was a 16 bit SIGNED Integer with range -32768 to 32767 is really an UNSIGNED Integer with range 0 to 65535.

    The testing thus far has pretty much convinced me, but I still need to do a few more experiments.

    Good Night.
    - Ivan.

  18. #868

    A Design Study

    Here are some screenshots from a design study that seems to be the natural follow on to the P-38 EJ Lightning. There is nothing shared between the two projects other than the subject matter.

    The problem here as usual is that my build method tends to be very expensive in polygon count.
    he EJ Lightning finished at 762 polygons. Just what you see here is already at 168 poluggons and with a pilot and some interior equipment will probably be close to 300 polygons.

    Dunno if this will ever end up as a full aeroplane. The budget will be pretty close.
    The shapes are still kinda cool though.

    - Ivan.
    Attached Thumbnails Attached Thumbnails Lightning_Nacelle3.jpg   Lightning_Nacelle2.jpg   Lightning_Nacelle1.jpg  

  19. #869

    pollugon?

    dear Ivan...
    what is a poluggon?
    papingo
    Last edited by papingo; November 24th, 2014 at 06:18. Reason: as usual spelin misteaks

  20. #870
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    it's smilo, not Ivan,
    my guess would be,
    a poluggon and a polygon are one and the same.
    except, they are spelled differently.
    which was, most likely, caused by fast typing
    and limited proof reading before submitting the post.
    that, or it was a test to see if anyone was paying attention.
    sometimes the magic works.
    sometimes it doesn't.

  21. #871

    As good explanation as any

    Sorry Papingo,

    I ran the word together a bit.

    It should be Pol-Ug-Gon: A really Ugly Polygon.

    Actually the count is now up to 172 poluggons now. I did a LOT of editing on the back side of the canopy to make it a bit more tapered and have the lines match up a bit better.

    I figured the P-38 might run for a while, so I started another thread.

    Hi Smilo,

    I was actually fairly certain there wasn't anyone actually paying attention here any more.

    - Ivan.

  22. #872
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    yeah, i know what you mean.
    don't get discouraged...
    easier said than done, right?

    remember, there are still a few interested in cfs1.
    they just don't say much. it is what it is.
    for example, if you look at your p-38 design study thread,
    the view count is already over 80 views.
    it's not earth shaking, but, it's not bad at all.
    sometimes the magic works.
    sometimes it doesn't.

  23. #873
    I fully concur, just because we are quiet doesn't mean we are not here. I was always told (many many times) to be silent when the teacher is speaking.
    Some stuff we already know but an awful lot is new ground for us and undoubtably fires our enthusiasm for CFS1 and AF99. The annoying thing is though the incredible abilty you have to point out the blatently obvious that the majority of us hasn't seen.
    please please please keep the reports coming

  24. #874

    CFS Audience

    Thanks Womble55.

    If your "blatently obvious" comment was about the Braking Factor post, I think now that it SHOULD have been blatently obvious. It makes so much sense now, but a week or two ago, I never would have thought about it.
    Incidentally, there are a couple typos in that post as well, but I don't have the ability to go back and correct things. I believe the meaning is pretty clear in any case regardless of typos.


    Hi Smilo,

    Working on stuff for CFS1 does get pretty discouraging at times. The tools are still pretty lousy even though I believe that Hubbabubba and I have come up with a bunch of tools and work-arounds.

    I don't really think the audience is all that big though:

    Look at the download count for the Richard Osborne Me 109E. I believe it is still in single digits which makes me wonder if the time spent on it was worthwhile. The only thing I can say is that I learned quite a lot about an aeroplane I wasn't very interested in.

    Regarding the P-38 Design Study, there may be 80 views, but I believe it is around 20 people who have each visited it 4 times. I know at least 3 of the views are mine from when I visit the thread to post something new.


    Hello Papingo,

    I am glad that someone is actually calling me on mistakes I made. I still can't figure out how I managed to corrupt the word "polygon" so badly. I don't suppose my 30 second excuse of an explanation about "Ugly Polygons" convinced anyone, but it sounded good at the time and we all KNOW that I don't make mistakes, right?

    ;-) to a most gracious audience.
    - Ivan.

  25. #875
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    just to let you know,
    as moderator, i have the capability to edit posts.
    for example, check the first post in this thread.
    i just did a little experiment.
    notice the color of the hyphen in front of Ivan.

    i don't believe it is my place to correct grammar or spelling.
    certainly, not from Mr D in High School English Class.
    that said, if there is something you would like edited,
    please, let me know and i will fix it for you.

    some comments about the me109e;
    first, i, personally, like this model...a lot.
    i intent on replacing the stock 109e with yours.
    one of these days, i'll work on european theater textures.
    but hopefully, a better artist will do it first.

    second, i notice that it has only been uploaded here.
    true, the download count is very low.
    consider that the 109e project had no specific thread
    and there was no download link provided when completed.
    (other than the link i just provided above)
    keep in mind that the 109e is now being buried in this thread.

    at the risk of getting my butt in a sling,
    i have to say that i believe the download library is....cumbersome.
    i have no doubt that for those that use it often, it's great.
    for me, there's just to much navigating...okay, i'm lazy. so?

    i prefer the free flight site for downloads and, for that matter, uploading.
    simply put, it's easy to use. the left panel menus are a breeze.
    for example, in the past year, hubba's w7 joystick patch
    has had 49 downloads here and 418 to date at his free flight site page.
    (not to mention, over 5,100 hits since july at the aac forum)
    and then, the ar196 just broke 500 at the free flight site.
    what this tells me is that there is still a cfs1 community.
    people are interested, just not as many as before and not so "vocal"
    might i suggest sending a copy of the 109e to Dave.
    i'm sure he would be happy to add it to your page there.
    sometimes the magic works.
    sometimes it doesn't.

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