Crumpp

Yes and a very good point. Quite a few World War II designs are neutral power on and stable power off.

Correct but lets make sure we do not misapply it to one aircraft and not the other. On the surface without a Reynolds number conversion for the P-51's NACA 44-100. We can take a small risk that Re number will not change the significance and say: Focke Wulf figure for a CLmax of 1.58 for the airplane gives good agreement with all the 2D data and the fact our full sized airplane will not attain the CLmax of 1.8. The North American CLmax of 1.6 of the NACA 44-100 also gives good agreement with the 1.41 CLmax calculated by the lift formula for the full sized P-51. A CLmax of 1.41 is not a "low CLmax" for a World War II fighter, it is just typical. Interestingly enough, the NACA concludes the change is ~.2 on the CLmax. 1.8-1.58 = .22 change coefficient of lift for the Focke Wulf 1.6-1.41 = .19 change in coefficient of lift for the P-51. That agrees with the NACA results. I agree with you on the laminar flow but that really has no effect on anything important to a DCS player.

And it does cause a pitching down moment in DCS. Problem is wanting the transition to be a pitch down. That is not correct. The change in trim is not the moment about the CG when the flaps are in transition from one position to another. It is after the flaps reach their set position. While the flaps are in transition, the moments created by the change in camber may not even be the dominant force acting on the aircraft. In most conventional tail aircraft, the increasing downwash causes an increase in the tail AoA causing a nose up pitch for a moment while the flaps transition. That is momentary and not something you trim the aircraft, trimming is for steady conditions of flight like maintaining Vref on approach.

Just learn to read it. Landing gear retracted = Drag reduction = Coefficient of lift reduction = Coefficient of moment increase = NOSE PITCHES UP Landing gear extended = Drag increase = Coefficient of lift INCREASE = NOSE PITCHES DOWN Flaps extended = Drag Increase = Coefficient of lift INCREASE = NOSE PITCHES DOWN Flaps retracted = Drag reduction = Coefficient of lift reduction = Coefficient of moment increase = NOSE PITCHES UP

I did not do the Re calculations for a 36 inch chord. I can do it later but I am sure they will be close just as the Lift formula predicts. Wind-Tunnel_Investigation_of_Profile_Drag_and_Lift..._Abbot,_Underwood,_1943.pdf

AI Bombers I would like to see... Allied (1944 line up) B17 B24 B26 Axis (1944 line up) Me410 FW190F8 AR234A

Sure thing. It depends on the conditions, jcomm. Here is the trim curves for the P-51; It requires a lot of nose down trim at high AoA. Yo-Yo definitely knows the specifics....

With flaps lowered, the airplane becomes nose heavy. The stability characteristics during transition from a clean wing to flaps down is going to depend on CG location and Coefficient of Lift. That can change with conditions.

Sounds like it is correct to me.

That is really the economic reality. While I would love a DCS quality T-6 Texan and I would fly it. I would rather see the Dev's put their time into other aircraft, maps and AI bombers over a trainer.

Stability and subsequently the pitching moment is coefficient of lift based. In other words, it will change with speed. What you see at one speed does not mean it will hold true for another. Application of nose up trim is also not designed for the transition period when the flaps are moving to the desired setting. The trim is for a steady approach condition of flight at that flaps setting.

:thumbup:

Very first post I asked: Which specific behaviors did you see that are different in a T-6 Texan? A simple answer would have been sufficient.

Ok, There is absolutely nothing in my post discouraging anyone from learning. In fact, it was meant to be encouraging. Why you have such a bug up your behind about...I don't know. :( I am sorry you got so bent out of shape when I disagreed with you on a very small point but that is your problem not mine. The point being of my posting was if you pay attention to the details the T-6 requires and read that article..... You should not have any problem with any of the DCS World War II aircraft. You have to got to be misreading something or just looking to pick a fight. I am not nor do I care if you cannot see reason. I cannot see a thing in that post that should offend anyone. Last thing that needs to be said. Take your personal issue to PM and quit hijacking the thread. Thank you. :thumbup: :smilewink:

Btw... I have nothing but encouragement for new players so I have no idea what is your basis for that allegation. Please relax and reread my post. Nothing derogatory towards you or anyone else.

I asked for specifics on what you felt was different about the T-6 on the premise I missed something in the artlce. The T-6 would be a fantastic aircraft for DCS, IMHO.

I do not know, maybe... :unsure:

Which specific behaviors did you see that are different in a T-6 Texan? Maybe I missed something! :) Everything I read in that article can be found in Taildragger Tactics and was nothing more than the basics of conventional gear aircraft. Of course, I am just relying what I know from my own experience. I teach it to my students when they want a taildragger endorsement. Having flown a T-6 Texan, I do not remember there being anything new as far as technique. The airplane has its quirks some of which are by design because it is a trainer. It is just somewhat unforgiving of sloppiness or mistakes. It definitely highlights any flaws a pilot might have in application of the basics. That is why it was nicknamed "The Pilot Maker". In fact that is almost verbatim from my introduction to the aircraft, LOL. http://advancedtailwheeltraining.com/tailwheel_basics Good picture of Bob Hoover... http://tailspinstales.blogspot.com/2009/11/taming-taildragger.html What he relates in the article about aileron to maintain position and rudder for direction on landing is what I have done on every landing since I started flying taildraggers. In fact, my taildragger experience has served me very well in professional flying simply because the basics are the basics. Because Tricycle gear aircraft are naturally stable, they will self correct. That does not change the fact the aircraft is still correcting what is really a pilot's mistake in not applying the correct control input. All of that advice he gives out for the T-6 is applicable to any aircraft and is taught as part of Private Pilot's license. It is just not critical in a C-172 so the muscle memory never develops. http://tailspinstales.blogspot.com/2009/11/taming-taildragger.html :P

The Bf-109 did have "excessive" elevator forces given the right conditions. The main condition being the pilot not following the engineers instructions on how it needs to be flown. Generally speaking, I think it was more of problem with the World War II designs going the opposite direction. It was more common for designers to set the forces too light than it was to make them excessive. Some common misconceptions drove that tendency. "Maneuverability is linked to instability" is one of them. Yes, but in terms of piloted aircraft only as far as it can be controlled and maintain his physiological requirements. You have to remember, in the context of the times they were outright horribly unstable aircraft in common use in General Aviation. The speeds were slow enough and weight low enough that control just was not the same issue it is with a 2000hp/10000lbs airplane brushing against the transonic realm of flight. Instability is just instability without control. If it makes the pilot unconscious, damages the airplane, or does not allow the pilot to put the aircraft precisely where he wants it to be... It is just instability. In the absence of modern aircraft control systems the designers options were limited to gearing, rigging, and the control forces. Even then, the effects were not always well understood. We have learned a lot both during and after World War II in terms of aircraft stability and control.

Yep, many World War II designs could reach the transonic realm and experience compressibility. The German's first encountered it in the FW-190 prototype. In dives, one could see visible proof of the Prandtl-Glauert transformation when the pressure gradient across the normal shock forms condensation in humid air. The Focke Wulf test pilot's had never seen such a thing and were shocked when the wings turned white in a dive. The airfoil selection on the Focke Wulf "critical mach" is fairly low. Critical mach is the velocity in which a normal shock will form on the airfoil. Good description of compressibilty and "mach tuck": http://www.wwiiaircraftperformance.org/fw190/fw190-0022-dive.html The transonic realm was such a new frontier that it was not until very late in the war, the mystery of what exactly happened to an aircraft's control surfaces under compressibility was solved by a very brave USAAF pilot for the NACA. Until somebody actually dove into compressibility, recorded the data, and survived it was hotly debated among engineers if the controls surfaces actually moved and several theories existed as the exact mechanism that cause them to be ineffective in compressibility. One my old college textbooks devotes several pages to this investigation. When I get home from work in a few days, I will dig up some good articles on the early foray's into transonic flight if folks are interested I think it is pretty cool.

All of that is just BASIC tail dragger piloting. That is why the T-6 was such a good training aircraft. It refuses to hide your flaws.

It is a great server IronJockel. Thank you guys for putting it up.

My engine locked up, on the same server as Diehard for no apparent reason as well. I was flying a P-51 and it locked up on take off roll. No overheats...just stopped.

IMHO, the P-38 did more to advance the NACA's practical knowledge of compressible aerodynamics than any other design. I hope we get one for DCS!! Development of High Speed flight.pdf

You could use trim to recover from compressibility in the Bf-109 and the FW-190 because of the adjustable stabilizer trim system. Look at gavagai chart for example, even at mach .82 when the elevator is ineffective because of flow seperation behind the normal shock, the portion of the airfoil at and ahead of the normal shock is still effective. In an airplane with an adjustable stabilizer trim system, that control will still work under compressiblity. You are right though, that control surface is very effective and a pilot risks overloading the airframe on recovery if he is not careful in getting out of compressibility. He is already well past Vne so might as well finish his test pilot run and see how it turns out. IIRC, Mtt instructs the pilot NOT to trim for the dive. This way the design stability and control characteristics require a push force in order to maintain the dive speed. If you trim for the dive speed against those instructions then the stick forces will be beyond what the designer intended and will be excessive. Congratulations, you are now a test pilot. Not really nor would it under modern stability and control standards unless of course you do not pay attention to what manufacturers tells you. If you do your own thing, then congratulations and welcome to world of test pilots. Hope you make out alive! :music_whistling: