P-51D Stall Speed

[Ramstein]

P-51D Stall Speed?

http://en.wikipedia.org/wiki/P-51_Mustang

 

When I fly, it feels like the stall speed is higher than what the documents say.. I don't have charts and stuff from my own experience, but it sure starts to be unstable long before the speed drops to near 100 mph..

 

Is there already talk about this?

I did a search and stall speed comes up in different contexts.. for differing reasons..

 

:joystick:

[Kaiza]

Stall speed is affected by many things such as altitude, weight, apparently weight (or G force), flap configuration and how much power you have on.

 

G force will have a very large affect on the stall speed which may be what you are seeing. The G force will increase the apparent weight of the aircraft by a factor of the G pulled. So a P-51D pulling 2 G will have stall a speed equivalent to what it would have at twice its level weight.

 

The 100mph quoted in wiki will probably be a rough speed at standard weights at sea level. To get an accurate stall speed you really need a P-51D stall speed chart.

Edited June 13, 2012 by Kaiza

[WildBillKelsoe]

Stall speed is affected by many things such as altitude, weight, apparently weight (or G force), flap configuration and how much power you have on.

 

G force will have a very large affect on the stall speed which may be what you are seeing. The G force will increase the apparent weight of the aircraft by a factor of the G pulled. So a P-51D pulling 2 G will have stall a speed equivalent to what it would have at twice its level weight.

 

The 100mph quoted in wiki will probably be a rough speed at standard weights at sea level. To get an accurate stall speed you really need a P-51D stall speed chart.

 

Define standard weight please? Is that 9000 lbs? And if so, the Gmax chart P.102 DCS Manual, would it define the stall speed for that matter?

 

EDIT:

 

The manual has the stall speeds chart for different rack/load configurations P. 112, but I guess, unless the sim progresses any further, we'll have to keep it tight.

 

Any update on the P-51D at this point is immensely appreciated.

Edited June 13, 2012 by WildBillKelsoe

[JimMack]

P-51D Stall Speed?

http://en.wikipedia.org/wiki/P-51_Mustang

 

When I fly, it feels like the stall speed is higher than what the documents say.. I don't have charts and stuff from my own experience, but it sure starts to be unstable long before the speed drops to near 100 mph..

 

Is there already talk about this?

I did a search and stall speed comes up in different contexts.. for differing reasons..

 

:joystick:

 

Please read the flight manual in the DOC folder.

Here you will find a stall speed graph for different speeds and G forces. Also the formula to re-calculate for different gross weights.

There is also a lot more interesting information in the flight manual.

[WildBillKelsoe]

Please read the flight manual in the DOC folder.

Here you will find a stall speed graph for different speeds and G forces. Also the formula to re-calculate for different gross weights.

There is also a lot more interesting information in the flight manual.

 

Any updates on the pony?

[Ramstein]

I looked (and read) the graphs, and looked up several websites about speeds, ias, etc...

 

is there a way in the P-51D to set a gauge to have a hashmark, a setting, that will show when you reach a presetting for say landings, take-offs, etc...

A needle mark (red?), an alarm? etc..

 

example: in the Ka-50 I like to set a hover height, that if I hit that setting an alarm goes off.. telling me I have reached my pre-set altitude alarm setting...

 

Or is it back to guestimating,,, I doubt if I will be taking out my scientific calculator anytime soon everytime I fly my combat sims..

:doh:

[cichlidfan]

No way to set anything like that. Much older avionics.;)

[Gaanalma]

Here will be some test for P51-D Mustang....will be some charts speed!

 

http://www.wwiiaircraftperformance.org/mustang/mustangtest.html

[peter]

The only thing that affects stall speed is angle of attack. You can stall the P-51 at 60mph or 250mph. It just depends on how hard you pull. A wing stalls because the air going over the top of the wing becomes disrupted, this can happen at any SPEED and is called an accelerated stall. Regardless of how fast you are going a wing will stall at the same angle of attack (AOA) for any given weight.

[ShuRugal]

well, unless the plane has an AoA meter, the pilot has to use things like IAS and known aircraft weight to judge when airflow separation will occur.

 

since the P-51 lacks an AoA gauge...

[BSS_Vidar]

Peter is correct. To be more precise, that term is "Critical Angle of Attack".

[effte]

In the industry, if you talk about 'stall speed' without further qualification it is implicitly understood that it's the 1G stall speed.

 

If we are to erase all simplifications and cover all the details, a single constant critical angle of attack is also a simplification. :)

[leafer]

This is new to me because I did not know there is more than one stall speed for any given aircraft. I always read manufacturer spec where they list one stall speed.

[sobek]

This is new to me because I did not know there is more than one stall speed for any given aircraft.

 

There's an infinite number of stall speeds for every aircraft. :)

[leafer]

I promise to glean the fine print before I buy more aircraft. So what causes that snap and left roll when I pull hard on the stick even though I have plenty of speed?

[sobek]

I promise to glean the fine print before I buy more aircraft. So what causes that snap and left roll when I pull hard on the stick even though I have plenty of speed?

 

Stall. :)

 

Think about it. A stall is when the angle, at which the airfoil travels through the air, becomes so great that the air will not flow "evenly" over the top of the wing but instead will create a lot of vortices and turbulent flow behind the wing edge (well there usually is no one angle at which this suddenly happens, what is usually the case is that AFAIK this zone tends to move further towards the front of the wing, starting out at the back, and the less area of the wing that has laminar flow, the less lift it will generate). Usually when you sit in an actual airplane and pull g's, you will (depending on how rapidly this sets on in the particular type of AC) at a certain point notice that if you pull any harder on the stick, g force will get less.

 

And that is the point. Stall is caused by angle of attack. What influences angle of attack? Speed and gs you pull (also, plane weight, but that is secondary in out little thought experiment). The more gs you want to pull, the more speed you need so you don't enter a stall first. The slower you go, the less gs you can pull until eventually, you "run out of gs" that is, your airplane can't even sustain 1 g without a stall. That is why there is an infinite number of stall speeds, depending on the load you pull.

Edited June 15, 2012 by sobek

[Bucic]

The best way is to check the graph included in the manual provided by ED. Then the second best thing you can do is to develop your own ability to evaluate stall conditions for any given moment. You can do it similarly to this:

As Bob said it's clear you're new not only to the 25 but also to flying. While the stall speed http://www.faa.gov/library/manuals/aviation/pilot_handbook/ may be ~270 for a lightly loaded A/C (aircraft) it can be over 300 for maximum takeoff weight and much higher than that for m.t.w. at even higher altitude.

 

Now, while key number values must be remembered you have to learn to instinctively, continuously and correctly adjust your airspeed to current conditions (weight and altitude). Here's how you develop this skill quickly. All you need is an ability to set up simple flights in the mission editor.

 

Level 1 - static, low altitude

a) minimum weight, 350 km/h close above flat terrain

Maintain level flight (vertical velocity indicator is the critical instrument here - not "artificial horizon" let alone the altimeter!). Retard the throttle to begin slowing down. Make the slowing down slow. The closer you get to 300, the slower. Compensate for the descend by pulling back on the stick. Continue until you stall, pulling back on the stick till the moment you crash.

 

a2) same as above but...

Try not to stall completely – don't slow down further when you feel you can't stop the A/C descending. Note down the weight, minimum airspeed and altitude. Now accelerate by ~50 km/h and decelerate back to minimum speed. All still flying close to the ground. Repeat few times.

 

a3)

Fly ~20 km/h above stall speed, ascending and descending by ~20 meters. Do a sort of flat sine in the air. Smoothly.

 

a4)

a1) through a3) above – all the same except you set up the flight with maximum takeoff weight.

 

 

Level 2 - static, high altitude

Level 1 steps a1) through a4) – all the same except you set up a flight at high altitude, behind a big A/C like A-50.

 

 

Level 3 - dynamic, low altitude

Level 1 steps a1) through a4) – but don't make it smooth. Make gradually rougher moves on the stick. Even try to make a sort of “Pugachev's cobra”.

 

 

Level 4 - dynamic, high altitude

As level 3 - all the same except you set up a flight at high altitude, behind a big A/C like A-50.

Of course the values are for Su-25 and e.g. 350 km/h means 50-100 km/h above stall speed etc.

[skouras]

the corner velocity of the mustang is 250 miles

below that if you try to pull hard you will see stall charasteristics

Edited June 15, 2012 by skouras

[peter]

ShuRugal-"well, unless the plane has an AoA meter, the pilot has to use things like IAS and known aircraft weight to judge when airflow separation will occur.

 

since the P-51 lacks an AoA gauge..."

 

No, all you have to do is watch for signs of an impending stall, this technique works at any speed or aircraft weight, when you see/feel the buffet ease up on the stick. :)

[leafer]

Good info, people. Man, I feel like someone should fire me for not knowing this. :D

[effte]

the corner velocity of the mustang is 250 miles

above that if you try to pull hard you will see stall charasteristics

 

Corner speed, for max instantaneous turn rate, is usually at manoeuvring speed, Va. Below that, you will see the stall before exceeding the design loads of the aircraft. Above that, you may bend metal or pop rivets before stalling the wing.

[OldCrow47]

My 2 cents

 

Now isn't the P-51 laminar flow wing design even more sensitive to AoA and accelerated stall? I have read where it will stall and roll over with next to no warning. If true then a RW pilot just has to know and feel the airplane. Waiting for an instrument to tell him he is stalling would be useless. Since we sim pilots sit in a RW chair we are at a big disadvantage in that we can't feel the aircraft (enter FF). So, no substitute for experience and stick time. Just like TO and landing...practice and more practice.

 

So many combat sims had aircraft you could yank the stick around like crazy and fly like something out of an old arcade game. NOT any more, we have to fly much more intelligently and let go of the yank and bank mentality. It really is a challenge to fly the Mustang, isn't it?

 

Jim

[sobek]

Now isn't the P-51 laminar flow wing design even more sensitive to AoA and accelerated stall?

 

There is supposedly a very slight buffet and there might be some other cues like wind noise in the pit of the real thing. But you are right, the Mustang was notorious for having very little buffet prior to stall. I guess that the forced stall behaviour is one of the reasons why snap rolls are so strongly discouraged in the Mustang.

[Ramstein]

maybe pilots who fly tail draggers or if we are really fortunate, a real P-51 pilots will chime in on stall speeds for landing, and takeoffs...

 

I know of several real pilots, who have flown wwii planes, during Korea...

unfortunately neither has the P-51 currently, so they can't comment. I am not sure if they plan on buying P-51D, as they currently fly IL-2 series, but are slwoing down with flying a smuch as they used to...

 

One of them loves to do the engineering aspects, mathematics, and explain stuff from both engineering and real life experience, from Props and Jets in their careers... he also flew planes in the navy off carriers, and knows a lot about stall speeds in wwii and Korea error aircraft.. but, for now, I have to rely on the forums, and from everyone's experience that posts here..

 

I have flown in real life, but didn't take off and land, and all the other aircraft I was a passenger while in the USAF.

 

I really don't want to bring my calculator out to take off and land... if the manual says 120 mph (IAS ?) and flair, and cut power to 90 mph,, fine, I will work on that.. It is just that I had questions about the stall speeds... and dropping wings at stall speeds, etc...

 

I understand it is Beta, and things can change... I appreciate all the info from all points of view.. While flying witha joystick, on a desk, in 2d looking at a computer monitor, with no feedback fromt he stick, and a very shaky hand makes it hard to get the best take-offs and landings... The DCS series has the best modelled flight sims every made, at least for the end user entusiast.... I was really wondering if in real life, in the P-51D, is with 30% fuel, no weapons, no wind, actaully performs a good landing without dropping a wing at 100 mph (IAS ?). ? Or does the wing drop at 120 mph? or 90 mph? I know in the sim, my P-51D Beta seems to be on the knife's edge of dropping a wing at slightly above those speeds... it's very hard to tell, because my eyes are so damned busy trying to keep the plane from dropping a wing, I can't watch the gauges when I am almost ready to touch down, I am watching too many things to concentrate on a couple of gauges..

 

And if I feel that I am going to be a bolter, then I have to make sure I can do that successfully and come back around.. which means I have to anticipate having ot gather engine power and keep the plane leve as I powe rit back up just at tha tpoint where I have commited to land..

 

So, That is why I was asking about stall speeds.. charts are great sources of information... but most of th e hcarts have to deal with actual in flight higher altitude and higher speeds. I think more about take-offs and landings.

I can feel the stall speeds, with a joystick and a monitor while I fly, drop weapons,a nd dogfights,,, but I find it much harder to take off and land. Actually, landings are my weakest part of flying... The stall speed when landing is hard for me. Shaky hands makes it very hard. Yes, I knwo there are easy settings... but if everyone on the server want's the most realistic settings I can appreciate that.. and expect that.

 

So, that is what I am looking for when people post about stall speeds.

 

Thanx for all the info you guys have.. Hopefully a real P-51 Pilot can chime in with landing info.. That should be very interesting..

 

IMHO

:joystick:

Edited June 15, 2012 by Ramstein

[effte]

The airplane has a comparatively mild stall. The airplane doesn't whip at the stall, but rolls rather slowly and has very little tendency to drop into a spin. When you release the stick and rudder, the nose drops sharply and the airplane recovers from the stall almost instantly. When a complete stall is reached, a wing drops. If you keep pulling back on the stick when the wing drops, the airplane falls into a steep spiral. In a straight power-off stall, some warning is given about 3 to 4 mph above the stall by a slight elevator buffet. A high-speed stall is preced by a sharp buffeting at the elevators and wing root, but recovery is almost immediate when pressure on the stick is released.

 

Rather benign, if you ask me. I've flown worse.

 

There's a stall speed table as well. Flaps down, gear down, light (8000 lbm) stall speed is stated at 87 mph. Add a thousand lbm for 94 mph. Sim stall speeds seem plausible to me, without double checking for exact weights.

 

Nothing about snap rolls per se, but they very specifically warn about the characteristics in a power-on spin, which probably is good to take to heart before attempting snap rolls. After all, a snap roll is effectively a spin entry.

 

Ooooh, this is a good one as well, while we're at it:

Rudder control

Because of the reverse-boost rudder tab and dorsal fin, the airplane has very good directional stability, with a directional change requiring definite pressure on the rudder pedal in proportion to the amount of yaw desired.

 

Sound anything like the squirrely beast of present? Didn't think so. But, it's beta and the control surface hinge moments are right in there in the list of WIP. :)