And... another flaps topic

[F/JG300_Gruber]

Hey guys,

 

 

Far from the heat of the Fw FM issues and yak magic flaps topics,

 

And just wanted to ask to the community of aerodynamics and physics enthusiasts their opinion about the Ju87 flaps, especially their response in the take off position.

Since I bought this sim, I've always found this harsh change in pitch behaviour quite ankward. Having to push the joystick all the way to prevent gaining altitude for a mere 50km/h excess in speed doesn't feel very realistic. On take off with a heavy load this is even more dangerous and I've seen quite a few pilots hit the trees or stall to death in the process.

 

On the other hand, I've never read anywhere that the Stuka had any vices like this, and that despite being slow and vulnerable, it was a "good hearted plane" easy to fly without bad surprises. Cpt Eric Brown also didn't had any comments on the matter (and he was quite eager to notice the pitch responses to flaps in his testings).

 

I don't have anything to back this up, no charts or anything and I understand that the subject might be complex due to the gull wings and the unusual fixation of the flaps on the plane, but I'm curious about your opinion about this, because to me it feels like something isn't right.  

 

 

As not a lot of people really care about this plane, and this will never be a game changing stuff,  I hope the topic won't degenerate like many others 

 

 

[JG13_opcode]

I would try asking people like Mike Williams or maybe Kurfurst to see if they have any Stuka data.  It's kind of a long shot, but who knows?  Maybe a plot of flap deployment angle vs pitching moment coefficient is kicking around.

Edited July 25, 2016 by 13GIAP_opcode

[216th_Lucas_From_Hell]

Not a solution to your query but maybe a hint, a couple of Developer Diaries ago they displayed a video of a Yak-52 pitching up when flaps are deployed and the stick is left at a neutral position, with the main catch being that in a real aircraft the stick would take a forward position by itself which is hard to replicate in a sim unless the user has a FFB stick.

 

If the Ju-87 follows the same trend, then test pilots would not have noticed such drastic pitch-up behaviour because they had 'FFB'. If the effect of the Ju-87 flaps in the sim is even slightly overdone compared to real life, it will feel way over the top since it's augmented by the lack of a stick which interacts with the aircraft.

[6./ZG26_5tuka]

Would be interesting to hear how FFB stick users percept this behaviour.

 

Edit: From Ju-87 D-5 Kurzbetriebsanleitung (translated version)

 

III. Take-Off
1. Roll stright for a few meters to align tail wheel, then set tail wheel arrestor to 'lock'
2. Check that flaps are in 'Take-Off' position
3. RPM control lever fully forward
4. Smoothly increase throttle until max
5. 1-min-setting: 2600 RPM at 1.40 ata
6. After lifting off immediately pull back throttle and RPM control lever to 30-minute-setting of 1.25 ata at
2400 RPM
7. Do not retract flaps until reaching a certain altitude (ca 200m) and V0 = 180 km/h because the aircraft
will lose altitude when the flaps are being retracted

8. Reduce power setting no later than 30 minutes after Take-Off to maximum continous output (2250
RPM at 1.15 ata)

 

Even the Ju-87 B-1 manual confirms this.

 

Verstellklappen erst in ausreichender Höhe einfahren, da das Flugzeug durch die Lastigkeitsänderung etwas an Höhe verliert.

 

Retract flaps only at sufficient heigh, since the airplane loses some altitude due to load changes.

Edited July 25, 2016 by 6./ZG26_5tuka

[1PL-Husar-1Esk]

I can say that this is not implemented in FF effects yet, but will be - look at DD120. Loosing alt (dip down i say) after take off wirh full flaps when to soon retracted is present, there is no forward pressure/ push on FF stick.

[Holtzauge]

Well IMHO there should be a nose-down moment effect also for non-FF sticks when you drop flaps just as you see for the planes with trim tabs on the elevator because both affect the elevator hinge moment: The effect to the person holding the stick will be the same in both cases irrespective if this was caused by a trim tab deflection or due to a change in the flap angle (which will change the downwash angle on the tail). So if one effect is modeled for a non-FF stick why should it not be modeled for the other?

 

There is actually an interesting discussion here in the DCS forum on the matter and how this could/should be modeled and weather it should be noticeable for non-FF sticks as well. Nice touch BTW that the DCS developer Yo-Yo asks the community what they think.

[Willy__]

The airplane does sink and lose some altitude after you retract flaps. But correct me if I'm wrong, but the OP wants to know about the behavior of the aircraft after you DEPLOY flaps, not after you retract.... Anyways, I own a non-FFB joystick and when I deploy flaps the airplane wants to nose-up in a very angry manner... makes up for some funny landings though...

[F/JG300_Gruber]

The airplane does sink and lose some altitude after you retract flaps. But correct me if I'm wrong, but the OP wants to know about the behavior of the aircraft after you DEPLOY flaps, not after you retract.... Anyways, I own a non-FFB joystick and when I deploy flaps the airplane wants to nose-up in a very angry manner... makes up for some funny landings though...

 

Pretty much it, though when you retract flaps there is also a pretty severe nose down change in pitch.

I understand that the aircraft may loose altitude when you retract the flaps (thanks 5tuka for the manual translation !), but it could also just "sink" without having such a big nose down motion.

 

I mean, take the aircraft in a clean configuration, 100% fuel, trim it for a level flight at 250kph and then deploy take off flaps without any input on the stick. the nose will just skyrocket to a +/- 80° positive attitude and then stall the aircraft. Even at 220/230kph, the aircraft just cannot be trimmed for level flight with TO flaps. And a small change of 10kph in airspeed translates in a large correction on the trim wheel.

 

I know that pitch response with flaps deployment/retractation is perfectly normal (I'm experiencing it in my cessna as well), but with such hard manner, I find it a little strange. 

[6./ZG26_5tuka]

I understand that the aircraft may loose altitude when you retract the flaps (thanks 5tuka for the manual translation !), but it could also just "sink" without having such a big nose down motion.

I very much share your impression and it's one of the things that bugs me most about the 87 FM. It makes it unpleasent to fly at times. The truth probably lies in between the notaion in the manual and what Lucas said about the lack of proper stick force modeling in BoS.

 

Wish I had proper RL expirience to contibute to that.

Edited July 26, 2016 by 6./ZG26_5tuka

[Monostripezebra]

 

 

da das Flugzeug durch die Lastigkeitsänderung etwas an Höhe verliert.

Retract flaps only at sufficient heigh, since the airplane loses some altitude due to load changes.

 

 

  "Lastigkeitsänderung" usually refers to trim change (Schwanzlastig/Schnauzlastig) , not loadchange. Same bit is still in some todays flightmanuals.

[Crump]

  "Lastigkeitsänderung" usually refers to trim change (Schwanzlastig/Schnauzlastig) , not loadchange. Same bit is still in some todays flightmanuals.

 

 

That makes sense.  The Ju-87 is designed to operate at high load conditions as a bomber.  A trim change to the aircraft means a speed change.  The aircraft will rise or fall to meet the new trim speed unless the pilot retrims it.

[YSoMadTovarisch]

[Edited]

Edited August 10, 2016 by Bearcat
Personal

[F/JG300_Gruber]

Really guys, just put crump on your ignore list, the amount of useful info he provides in proportion of the thread derailing and other craps ain't worth it.

 

Please hold yourself on these kind of comments, I would like this topic to stay clean of personal attacks. 

 

 

 

On the topic :

 

Having done a bit of test flying on the 87 recently. For the landing part, I found that a good speed for extending flaps was below 230-220km/h.

There she lifts her nose gently but the speed decays quickly and the plane goes back to a normal attitude quickly. A mild forward input on the stick is enough to control this. I'd say that 220km/h is the sweet spot for flaps.

 

My thought are that the problem may lie in how we tend to fly aircrafts on these sims. With our fighters with low drag characteristics and short landing circuits to save some time for the next mission, we tend (at least I) to use the flaps a bit like airbrakes in downwind leg. Of all the airplanes of the game, the 87 is the one that is the furthest away from a military fighter, and the closest to a civilian light aircraft (except weight ) and so it probably should be flown accordingly in the landing phase by letting the speed decay close to the approach speed before extending flaps. Starting using flaps in the 250-300km/h range like in the 109 or 110 isn't correct for the 87.

 

5tuka, is there any details about recommended flaps extending speed this in the 87 handbook ? 

[6./ZG26_5tuka]

Unfortunately not in detail. For the landing an approach speed of 150-160km/h (depending on weight) and flaps "as nessecary" are required per manual. In the Ju-87 B-1 manual it's also sayed that full flaps significantly steepen the approach angle.

[Dakpilot]

This (translated) article by Petrovic FM engineer, explains some of the reasons for the issues in RoF/BoS of some of the 'anomalies' regarding Joystick and trim

 

http://riseofflight.com/forum/topic/2564-about-wrong-elevator-position-and-pitch-sensitive/?p=22055

 

it is a bit long but worth wading through, it may give some extra insight in why real life and PC sim are hard to reconcile and some of the design choices that  have to be made

 

also do you apply trim at the same time you are deploying flaps, this may help

 

generally a flap setting will have a corresponding power and trim setting, (at a given weight)  in the RL this becomes sort of 'second nature' from experience, book figures and 'seat of the pants' and stick feeling

 

with these missing it becomes sometimes much harder  to 'subconsciously' set trim correctly in all phases of flight on a PC sim than in a real aircraft

 

Cheers Dakpilot

Edited August 2, 2016 by Dakpilot

[II/JG17_HerrMurf]

For me deploying flaps at the appropriate speeds and flying a slightly modified circuit is the ticket. As a Fw guy I cross midfield, low at 500+, check six, chop the throttle and break turn (75-90 degrees with a pitch up) into the downwind while bleeding speed. Turn base about 300 and drop combat flaps. Turn final and drop gear around 275. Last is full flaps around 250-260. Approach is 220, flare around 180-190, hold her off and touch down right at 168 in a three point if all goes well. More than one bounce and I feel shame.

 

You'd obviously have to make some amendments for a Ju87 but this combat circuit might help. The two critical speeds for me are optimum flap and flare speeds. I can fudge everything else and still have a good circuit.

 

Also, don't be afraid to ride the rudder and slip hard to shed speed in a pinch. Everyone b@tches about the Fw but you can almost "autorotate" her from 2500m right down to the threshold in a slip with practice.

[6./ZG26_5tuka]

Sideslip can be usefull but they way it's modeled ingame the effect is lower than what you'd expect. The Ju-87 does slip somewhat okayish but not as nitcely as the E-7 and Bf-110.

 

Fortunately they'll eventually take another look at the older FMs and their yaw induced roll characteristics.

[Crump]

 

Sideslip can be usefull but they way it's modeled ingame the effect is lower than what you'd expect. The Ju-87 does slip somewhat okayish but not as nitcely as the E-7 and Bf-110.   Fortunately they'll eventually take another look at the older FMs and their yaw induced roll characteristics.

 

 

Yaw roll coupling appears to be one of the more difficult things these home computer sims "simulate".  

 

So we are all on the same page about the mechanics of what a rudder is supposed to be able to do in order to be called a rudder!

 

1. Keep the aircraft in coordinated flight.   In a real aircraft it does not take much rudder to keep a bank coordinated.  If the ailerons are correctly balanced then there is very little adverse yaw some some aircraft require more input than others based on the specifics of that design.  The developers might be going for that effect or they might simply have overdone it.

 

Do not look at the ball (inclinometer).

 

 http://www.aircrafts...clinometer.html

 

Look over the nose and add just enough rudder so that the aircraft rotates about the longitudinal (lengthwise) axis just like there was a solid rod extending thru the propeller spinner to the tail.  If the nose yaws off that axis, the roll is uncoordinated.  Uncoordinated rolls can lead to stalls if excessive rudder input is used.  Usually they lead to a reduction in airspeed and a sloppy boat turn entry. 

 

2.  The rudder can always lift the wing at the stall point.  In a tractor propeller aircraft, the thrustline pretty much keeps some degree of effectiveness over the rudder all the way to zero airspeed.  A good pilot can walk the wing down in a level attitude on a high powered piston aircraft with rudder use.  Torque effects are always present but a wing has a tremendous amount of roll wise dampening that effectively covers up the effects.  Once the wing is no longer flying, that torque moment drops the wing until the angular velocity returns the dampening force.  Rudder can counteract this quite effectively and keep the wing level.

If you fly Cliffs of Dover, it has very poor roll-yaw coupling for example.  You cannot keep the wings level at the stall and it becomes this mushy non-airplane acting gameshape.

[YSoMadTovarisch]

[Edited]

Edited August 10, 2016 by Bearcat
Personal

[Crump]

Six days between post's....it will take a whole year to derail it....

[YSoMadTovarisch]

Six days between post's....it will take a whole year to derail it....

[Edited]

Edited August 10, 2016 by Bearcat
Personal

[Crump]

Completely false but keep telling yourself that.  You notice nobody antagonized anyone until you came along.  You contribute nothing to the thread except insults out of the blue.  This is my last post on the subject to you.

[YSoMadTovarisch]

Completely false but keep telling yourself that.  You notice nobody antagonized anyone until you came along.  You contribute nothing to the thread except insults out of the blue.  This is my last post on the subject to you.

 

[Edited]

Edited August 10, 2016 by Bearcat
Personal

[Bearcat]

KNOCK IT OFF.

 

Given that I just saw this.. this is the only warning you will get.