Questions about Aerodynamic Model

[Exorcet]

Something is off and while I am no engineer I just feel its due to not enough energy bleed off with no power.When my engine cuts out I expect the plane to drop like a rock but it instead just floats on and on.This is ok to live with as I try not to bust my engine BUT it in turn is causing my landings to feel off.With power off and landing I seem to float forever over the runway and find I need to pull too much on the stick which is causing three pointer landings.If I want to do a 3 pointer I would like to be able to initiate it but instead I find that I NEED to pull too much elevator to bleed off speed.

These planes have relatively high aspect ratios and straight wings and are light, they're not going to bleed speed at a tremendous rate even with no power. You could get a rough idea of the drag from these airframes with a few wing parameters, total weight, and an estimate of the fuselage wetted area. When you have the force you could apply it to the mass and see what kind of deceleration to expect.

 

To me it sounds like you're just coming in too fast, and maybe not using enough flaps.

[Silver_Dragon]

I think that tell over the absence of prop-wash at low RPM, speed (1000-2000 RPM). On that Su-26 take off video can see how the aircraft make a engine run test and the taildager tyre compression, fuselage and rudder was affect by the engine flow (1:14-1:18).

 

 

That effect don´t see on the P-51D or Fw-190D-9

[IIIJG52_Otto_]

 

PS:

otto, i saw you yesterday on the VA server, so just a side note:

IF you have auto rudder on and 100%, this will NOT work on the server. there you have to do it all manualy atm ;)

 

Your comment offends me, .. I have the SAITEK Pro Flight Rudder Pedals , and i no use that cheat of autorudder that you says., :(

[MACADEMIC]

From my experience, there's no shortage of prop wash in the flight model. Rudder responds immediately to inputs when taking off with full power upon brake release. Mostly a matter of practice to get used to the aircraft.

 

Take Off technique according to the original FW190-D9 pilot's operating handbook:

 

- straighten airplane

- full brakes, stick neutral

- smartly advance power to take off position

- release brakes

- small corrections with rudder to keep straight

- don't push stick forward only lightly feel forces on stick

- leave tail down until plane is ready to fly

 

Videos and track for illustration.

 

[EDIT: 0 wind, 0 trim, no helpers, Sony Dualshock 3 controller]

 

MAC

 

 

Take Off FW190D9.trk

Edited August 22, 2014 by MACADEMIC

[wolfstriked]

What I am finding makes the FM so hard to handle on landings for me is the planes RPM is very unstable when controlled with throttle.Take the P51 where you increase throttle and suddenly RPM spikes up.So when landing and you try to slowly close throttle to flare the RPM's suddenly plunge down and the torque effect causes wing dip and you overcompensate and then your all over the place.Is the real P51's RPM really that hard to manage?

 

 

DISREGARD THIS POST AS I WAS USING THE SMALL THROTTLE ON THE T.16000M.Just now I switched to my X55 throttle and its perfect.Sorry for the confusion.;)

Edited August 22, 2014 by wolfstriked

[wolfstriked]

These planes have relatively high aspect ratios and straight wings and are light, they're not going to bleed speed at a tremendous rate even with no power. You could get a rough idea of the drag from these airframes with a few wing parameters, total weight, and an estimate of the fuselage wetted area. When you have the force you could apply it to the mass and see what kind of deceleration to expect.

 

To me it sounds like you're just coming in too fast, and maybe not using enough flaps.

 

Try final approach in the Dora.I have to do a large slideslip or the plane is stuck at 400kph with no throttle.This is also flying into a crosswind so its not the wind pushing.

[IIIJG52_Otto_]

I think that tell over the absence of prop-wash at low RPM, speed (1000-2000 RPM). On that Su-26 take off video can see how the aircraft make a engine run test and the taildager tyre compression, fuselage and rudder was affect by the engine flow (1:14-1:18).

 

 

That effect don´t see on the P-51D or Fw-190D-9

I´m totally agree with Silver_Dragon, :thumbup:

 

..And in minute 0:10 of that video the Su-26 do changes of direction with the "prop-wash", applying rudder, and a hit of throttle. :thumbup:

[Yo-Yo]

I think that tell over the absence of prop-wash at low RPM, speed (1000-2000 RPM). On that Su-26 take off video can see how the aircraft make a engine run test and the taildager tyre compression, fuselage and rudder was affect by the engine flow (1:14-1:18).

 

 

That effect don´t see on the P-51D or Fw-190D-9

 

Are you kidding? Do you know the weight of this plane, wing and empennage weight/area ratio, engine power?

 

Some time ago I saw an owner of one of these planes complained that his plane was about to be blown away by the propwash of Yak-18T running at rpm 60% . His plane was 25 m behind Yak...

 

 

By the way, why don't you complain that Dora does not climb vertically as Su-26 does?

Edited August 22, 2014 by Yo-Yo

[IIIJG52_Otto_]

From my experience, there's no shortage of prop wash in the flight model. Rudder responds immediately to inputs when taking off with full power upon brake release. Mostly a matter of practice to get used to the aircraft.

...

 

Videos and track for illustration.

 

MAC

 

[YOUTUBE]W9ngPDfZRN8[/YOUTUBE

 

[YOUTUBE]zkz0QOdyXbY[/YOUTUBE

 

Do you have wind on the nose or tail?

* What wind speed do you have in the video?

How do you set the elevator trim? ..nose-up, neutral or nose-down?

 

If you are taking-off with 30 or 40 km/h of nose wind, probably you have rudder control from beginning of the take-off run.

[wolfstriked]

Crosswind 8ms TO and then landed it with some isses.....but I walked away.;)

 

 

And this is just a funny nose down that also looked kinda sweet!

[MACADEMIC]

Do you have wind on the nose or tail?

* What wind speed do you have in the video?

How do you set the elevator trim? ..nose-up, neutral or nose-down?

 

If you are taking-off with 30 or 40 km/h of nose wind, probably you have rudder control from beginning of the take-off run.

 

See Edit remark in my post, 0 wind.

 

MAC

[wolfstriked]

I posted about the throttle and spiking RPM's and then fixed my post as I realized I switched to using the small throw om my t.16000m joystick to test crosswind landings.Now I am back on X55 and the rpm matches my throttle BUT I think that it matches it too well.With the mass of the propeller spinning and you cut the throttle rapidly I feel that the rpm's should not rapidly drop like a direct connection.I think this gives the FM a bit much of a twitchy feel.No flying experience so its just a gut feeling.:pilotfly:

[aaron886]

Are you kidding?

 

Bad comparison, to be sure, but it is interesting to see how little rudder deflection he had on takeoff. (Blast-off? :D)

[wolfstriked]

Last one.;) Its another 8ms crosswind landing that was a bitch to keep on runway due to the plane wanting to severely lift a wing and steer into the wind.Its like my 12th attempt as I had no idea what was happening at first and then I realized I needed aileron.....and then a few more attempts and I realized I also need harsh braking to keep her straight.Tons of opposite aileron and brake pedal and I was wondering if these planes are supposed to land in this type of crosswind.I remember reading that WW2 had tons of airfields being just that,fields to land in so maybe these planes didn't do severe crosswind landings?Also,if anyone knows....would less flaps be advisable in crosswind landings?I think its the reason for the excessive wing raise.Gonna try it out.

Edited August 23, 2014 by wolfstriked

[NineLine]

Bad comparison

 

 

Really bad lol... cant the Su-26 hold itself stopped vertical for some time because of its power to weight ratio?? I think that was an Su26 I saw this year at the air show...

[aaron886]

Really bad lol... cant the Su-26 hold itself stopped vertical for some time because of its power to weight ratio?? I think that was an Su26 I saw this year at the air show...

 

In BC? Maybe. I don't think their power to weight ratio is quite that good, that sounds like one of the newer, lighter "Extra-type" airframes.

 

Last one.;) Its another 8ms crosswind landing that was a bitch to keep on runway due to the plane wanting to severely lift a wing and steer into the wind.

...

Also,if anyone knows....would less flaps be advisable in crosswind landings?I think its the reason for the excessive wing raise.

 

Yes, less than full landing flaps is usually recommended, primarily because you'll tend to settle at a slower airspeed with flaps extended. Try keeping a little more airspeed on that approach, you'll need some time in the flare to straighten the crab angle before touchdown. Your right wing might not have dropped if you still had control/airspeed. Remember that for the first part of the roll-out, all of your control is aerodynamic, and you'll need to keep some air over the control surfaces for that to work! With higher winds, in a tail-dragger you're going to be looking for a "wheel landing" rather than a "three point" touchdown.

Edited August 23, 2014 by aaron886

[Rocky49]

Sith

You are right, it can hang off it's prop. Notice it has a proportionally large rudder and still can't handle the torque.:music_whistling:

Edited August 23, 2014 by Rocky49
Spelling

[NineLine]

Yup, sorry, that was an Su-29 I think...

 

Su-26

 

Crew: 1

Length: 6.83 m (22 ft 5 in)

Wingspan: 7.80 m (25 ft 7 in)

Height: 2.89 m (9 ft 6 in)

Wing area: 11.83 m² (127 ft²)

Empty weight: 736 kg (1,619 lb)

Max. takeoff weight: 1,206 kg (2,653 lb)

Powerplant: 1 × Vedeneyev M-14P radial engine, 270 kW (360 hp)

 

Su-29

 

Crew: 2

Length: 7.32 m (24 ft 0¼ in)

Wingspan: 8.20 m (26 ft 10¾ in)

Height: 2.87 m (9 ft 5 in)

Wing area: 12.24 m² (131.8 sq ft)

Empty weight: 760 kg (1,675 lb)

Max. takeoff weight: 1,100 kg (2,425 lb)

Powerplant: 1 × Vedeneyev M-14P 9-cylinder radial engine, 265 kW (360 hp)

 

So the Su-29 at the Abbotsford airshow is actually heavier... it hung in a vertical stall from engine power for a fair amount of time, cool maneuver... so I imagine the Su-26 could do the same... regardless... hardly comparable to the 190 :)

Edited August 23, 2014 by NineLine

[Anatoli-Kagari9]

Well,

 

Déjà Vue! that's what I have to say about the many comments / complains about the "difficult" handling of the Fw190.

 

This was exactly the same movie when the p51d became available, and indeed the Fw190 is a lot easier to control in ALL phases of flight, from takeoff to landing ( even under strong x-winds (*) ) and in dogfight, provided you adhere to the rules - don't loose energy!!!, keep high and Boom & Zoom!

 

As I have been pointing out, and that certainly made me think for a while and with the help of Yo-Yo understand the level of detail put into the simulation of this Fw190 in DCS, I can only suggest a very simple experiment:

 

- Create a mission or edit one of the default ( I use the default P51d takeoff from Batumi mission, edit it, change the aircraft to the Fw190 D9, and set the wind to my liking... ), and set the wind so that it comes directly from 9 o'clock or 3 o'clock, with a speed no less than 10m/s.

 

Now, aligned with the rw, start your takeoff run and observe.... correct, correct again, try to keep her straight until you're good to go and takeoff.

 

The proof of a very sophisticated model of propwash being present in this sim, and model, and that actually now also affects the p51d, is that your spliraling slipstream gets a huge deflection due to the wind speed. While you're stopped, or just starting your takeoff run, and your rudder authority is weak, the displaced slipstream is deflected downwind, hitting your downwind wing with considerable intensity ( a considerably wide flow moving at around 130 km/h at takeoff RPM! ), as well as your downwind side horizontal stab, vertical stab, and fuselage.

 

As a consequence, and although you will soon start to weathercock, as you gain speed, those first moments after you release brakes and start accelerating are going to present you with a "surprise" for, instead of weathercocking you'll find yourself fighting against the tendency of the aircraft nose to drift downwind, and it downwind wing to raise. You will naturally fight this with rudder into the wind and opposite aileron ( so, trying to get the downwind wing down... ) - Problem is, as soon as this effect of the deflected slipstream fades, you'll be in trouble because you've been doing exactly the opposite of what you were supposed to do - rudder downwind, and aileron into the wind!!!! Prepare to be quick, very quick and precise correcting and getting back to a stabilized takeoff.

 

This is why takeoffs in powerful taildraggers with strong x-winds are prohibitive! This is also why DCS World is such a different light simulation, and one that get's me strongly tied to it!

 

Last but certainly not least, this is why I have Yo-Yo and the ED team in my higher consideration, for risking the implementation of such a sophisticated flight dynamics model, knowing that it may well contribute for the accumulation of negative / uninformed opinions from all of those who haven't yet mastered the techniques, after all the RL techniques, of flying a powerful taildragger in a flight simulator as close to reality as I believe is possible.

Edited August 23, 2014 by jcomm

[sobek]

Bad comparison, to be sure, but it is interesting to see how little rudder deflection he had on takeoff. (Blast-off? :D)

 

Also interesting to see how the rudder is ridiculously large compared to the weight and size of that aircraft, no?

[gavagai]

Kakie vashi dokazatelstva?

 

 

:clap_2:

[Nedum]

I think most of the things you listed there are more likely related to pilot error than anything else ;)

 

AI Pilots... please read again... :thumbup:

[Nedum]

Have you flown anything remotely like a Fw 190D-9 in real life? I have driven a Ford Escape, so I should know how a race care should handle on the track at 200mph ;)

 

Oh com'n... we' ve the P51 to compare.. please read the OP fully! ;)

 

But is that the flight model or is that those crappy plastic controllers we have sitting on our desks, I would imagine this is one of the most delicate moments in a flight... subtle inputs are probably called for, you dont always get those with even the highest quality sticks... especially when we start talking the different in length of our flight sticks compared to the actual ones... remember these sims are done with the real thing in mind... not my stubby X55....

 

Working with the P51.. hmm.. let us think about this...!?

Edited August 23, 2014 by Nedum

[Nedum]

I think this item will be discussed again and again like a tide. The first wave was after P-51 beta had been released, then after its public release... the Dora tester's wave was not too high. Now we have the next wave.

 

So, I have to repeat some statements from this discussion.

 

1. The taildragger IS UNSTABLE as it rolls up to the speed when the stability due to its fin begins to prevail over instability due to its undercarriage.

2. Propwash is nothing for the STABILITY because it is almost fixed to the axis of the plane. It turns with the plane so it can not stabilise yaw movement.

3. Propwash is very powerful for the CONTROLLABILITY. The more power is applied the more agile is the plane reaction (at low rolling speeds).

By the way, one can feel it starting TO run in Dora with unlocked tailwheel at full power - it seems that it goes for the pedals "sitting tight" in the propwash.

 

4. Anyone can turn TO assistance on and start roll fixing rudder to 1/5-1/4 right. Watch the track - and notice that your "instructor" tapped as the real pilot does while your plane goes ideally straight. It even applies right rudder as the nose goes down and then release it even more than before rotating. AS in real life.

5. The last but not the least: the main challenge in the virtual world is to learn how to compensate the lack of acceleration info using only visual perception.

 

sic

 

 

 

Google more themselves for "Ground loop"

 

Ähm.. what you guys think about us?

 

The first Vid shows a pilot mistake and he was on gras and the runaway had a few degrees sideslip.

 

In the second one the tail wheel was clearly "broken" at touch down.

 

So what will you show us?

That clear Pilot mistakes compare to non mistakes of us?

Or that a broken wheel shows the cautious of a full functional rear wheel in DCS?

 

:huh:

[Yo-Yo]

The whole thread is about PILOT'S MISTAKES. As MACADEMIC and dozens of people show - there are no problem to taxy, takeoff and landing Dora. So, the problem is not in the physics... taildraggers have their own physics that can bite you if you make a mistake. That's the point.

Edited August 23, 2014 by Yo-Yo