CAS plane and grassports (and some other stuff)

[RushHour 11]

Has anyone managed to take off from the grassport up in the northen region? (north west)

I also noticed that the most extreme flap setting do not produce more lift then the first flap setting which is strange. Seems to me flap settings does nothing other then create drag. I can´t feel any difference in lift.

Seems like the only thing that will be able to take off on those grassports are STOL cargo planes like A400M and C-17.

Another odd bit is that it´s possible to land the aircraft at the airport even though you are coming in at much higher speeds then you would if you were to take off.

[chortles 263]

Are you talking about Stratis or Altis? Because I was able to take off just fine from Stratis Air Base's runway, south-to-north.

[RushHour 11]

Altis,

By grassport i mean airport on grass. Not a real properly built airport.

Tried the one to the south east as well, flaps makes no difference at all, and it´s incredibly bumpy, a bit too bumpy for an airport, even one that just got some cones and lines.

Are the BI team aware of the Coanda-effect?

http://i.imgur.com/FYG5ajN.jpg (161 kB)

With the flap angle the air flowing over the wing will actually follow the shape of it, meaning it will bend and go down = generating lift.

Some aircraft even puts their engines on top of the wing to not only have the air produce the coanda effect but also the engine exhausts.

Edit: here´s an updated image of the airflow and how it is being affected by the flap angle, roughly speaking.

Edited September 6, 2013 by RushHour

[da12thMonkey 1943]

Fully extended flaps are only really used in landing to reduce the stall speed and allow the plane to make a slower approach. During take-off they create too much drag and result in a poor climb rate (as in real life where flaps are usually never extended more than about 10-20 degrees during take-off).

Rather than doing the whole take off run with flaps down, try picking up some speed by doing some of the take off run without flaps, before deploying them at the first setting in order increase lift before you reach the end of the runway - It might help, depending on how well the aircraft accelerates on that rough field. However, I wouldn't be surprised if that airfield was too short and too rough for the Buzzard to take off from

[RushHour 11]

Correct,

I did some testing on the main airport, just to see if it takes of by itself.

Without any input only the middle flap setting will lift the plane up by itself, most extreme setting will hit a wall at just under 200 and no flap setting won´t create any lift (on the length of the runway at least)

Actually while i´m doing this, i might as well do it properly, test everything and write it down so we get a full overview of what speeds does what, what flap angles does what, how long of a distance it needs to land/take off etc.

Just going to watch Formula 1 then i´ll start.

[five_seven5-7 56]

more things that are also inaccurate: a jet fighter that can´t achieve a good service ceiling, a supersonic speed (sonic boom sound / Prandtl–Glauert singularity happening), poor thrust and so on

[Redphoenix 1540]

If you take the momentum when taxiing +half-flaps, you should get of the grass airports with ease.

Cheers

[mrflay 4]

Has anyone managed to take off from the grassport up in the northen region? (north west)

The L-159 Alca has a take off distance of about 440 meters. Which is also what the A-143 Buzzard has in game. The northern airstrip is about 330 meters, so in my opinion it should not be able to take off from there.

Although, the L-159 has a 750 meter landing distance, while the A-143 can land "safely" in about 50 meters. :)

[doln 10]

more things that are also inaccurate: a jet fighter that can´t achieve a good service ceiling, a supersonic speed (sonic boom sound / Prandtl–Glauert singularity happening), poor thrust and so on

The ALCA is not supersonic

[RushHour 11]

If you take the momentum when taxiing +half-flaps, you should get of the grass airports with ease.

Cheers

Not sure i fully understand what you mean, could you explain with some different words?

---------- Post added at 13:11 ---------- Previous post was at 12:55 ----------

Hmm this is a bit weird, now the plane will take off by itself with maximum flap angle and it will exceed well over 200 quite easily. correction, well over 500km/h..

And with no flaps it won´t take off. And with medium setting it now won´t take off from the ground...

How can this be? It seems the game generates random physics every time you start up the game, and once you are in, those are the physics you will have until you exit.

Lowest Flap Setting - 193-197km/h before crashing. No lift.

Medium Flap Setting - 203km/h before crashing. No lift.

Highest Flap Setting - hits´s over 200 long before the other flap settings, and takes off with no problems.

Here´s a video showcasing the different flap settings. BI it would be very helpful if you could explain what is going on, i know it´s a DEV build but this honestly does not make any sense.

http://www.youtube.com/watch?v=3sf1fLg_pK0&feature=youtu.be

---------- Post added at 14:36 ---------- Previous post was at 13:11 ----------

Ok made a ticket now, hopefully they take a look at the flap angle physics.

http://feedback.arma3.com/view.php?id=14085

Edited September 6, 2013 by RushHour

[RushHour 11]

I don´t want to spam my post but i would greatly appreciate if every flight fan of Arma would vote on the ticket, we just have one plane now so it would probably be fixed before others arrive.

Edit: it´s been reviewed, woho :)

Edited September 6, 2013 by RushHour

[thx1137 10]

The L-159 Alca has a take off distance of about 440 meters. Which is also what the A-143 Buzzard has in game. The northern airstrip is about 330 meters, so in my opinion it should not be able to take off from there.

Although, the L-159 has a 750 meter landing distance, while the A-143 can land "safely" in about 50 meters. :)

I haven't been able to though ProGamer says he can so I closed my ticket about making it possible. I assume it must be because if one guy can do it we can all do it though buggered if I can. Even with a run-up.

---------- Post added at 06:44 ---------- Previous post was at 06:19 ----------

I also noticed that the most extreme flap setting do not produce more lift then the first flap setting which is strange. Seems to me flap settings does nothing other then create drag. I can´t feel any difference in lift.

I don't fly jets (just two seaters) but full flaps is not for takeoffs in any plane I know. As you say, way too much drag. I use full-flap on standard landings so I land at a lower airspeed and good airfield visibility but note that at full flaps I need a fair bit of engine power to the overcome the induced drag.

It had occurred to me that the ground friction might be a bit high due to the short stopping distance. If it is high it would impede takeoff acceleration too. I thought it might be because of ARMAs funny throttle handling giving us something like reverse thrust.

All that said. I do like it. I just really want to be able to use that strip with it due to a mission I wanted to create.

Try just accelerating down the runway and note speed at end of runway.

Flaps Speed Behaviour

----- ------ ----------

Zero 190 kmh On the ground still.

One 207 kmh Feeling a little light but still on the ground

Two 235 kmh Flying.

That actually looks ok to me.

With zero flaps it should stay on the ground due to the symmetric airfoil

With one flap it it light due to a mslla amount of lift. Being in ground effect and the wheels not dragging as much we could expect a bit more airspeed.

With two flaps. Assuming the jet has the thrust to counter the heavy induced drag it would take off.

I can't say I see any effect on stall speed in flight though.

Edited September 7, 2013 by thx1137
Added my findings on flaps on takeoff

[HorbeySpector 164]

I think the grassport is still WIP. I landed there yesterday without a problem, but when I tried to park the plane in the hangar, it got stuck because the wheels didnt go over the 'entrance' of the hangar.

[mrflay 4]

I haven't been able to though ProGamer says he can so I closed my ticket about making it possible. I assume it must be because if one guy can do it we can all do it though buggered if I can. Even with a run-up.

These takeoffs all work for me (full or half-flaps):

http://cloud-2.steampowered.com/ugc/600391697217528584/2245248027A83C9D0C4799F5F695E4D28F283402/

But still, the airfield obviously is not designed for jets.

Edit:

Edited September 7, 2013 by mrflay

[thx1137 10]

Thanks mrflay. Appreciated. I'll have to give it a try based on that image. I had thought about using a road but I do like to follow standard procedures though (I think they would be pretty pissed off at my airfield if I used anywhere else IRL!) and in my mission the area was hot so I didn't want any mucking around.

[RushHour 11]

Barely got out of that one, we should thank the bushes for not being physical.

But it´s great to so see someone doing it, seems like you need to get some momentum there in the beginning which is the key to just barely having enough speed to produce lift.

Try just accelerating down the runway and note speed at end of runway.

I have, this is what my video is showing, it´s only X all the way down.

Flaps Speed Behaviour

----- ------ ----------

Zero 190 kmh On the ground still.

One 207 kmh Feeling a little light but still on the ground

Two 235 kmh Flying.

That actually looks ok to me.

With zero flaps it should stay on the ground due to the symmetric airfoil

With one flap it it light due to a mslla amount of lift. Being in ground effect and the wheels not dragging as much we could expect a bit more airspeed.

With two flaps. Assuming the jet has the thrust to counter the heavy induced drag it would take off.

I can't say I see any effect on stall speed in flight though.

But the drag/accelleration/speed is wrong though. Most drag equals slowest acceleration and top speed.

Do you get the same numbers if you start up the game again?

Edited September 7, 2013 by RushHour

[progamer 14]

I haven't been able to though ProGamer says he can so I closed my ticket about making it possible. I assume it must be because if one guy can do it we can all do it though buggered if I can. Even with a run-up.

Message me about your ticket, but I assumed it was about you couldn't take off at the really small airport but then that was proven wrong. Rush's ticket about flaps has been reviewed though. That runway also looks like it isn't made for jets to land there in the first place though I landed there first try from sides and took off second try when the jets first came out.

The issue I find with aircraft right now is that wheels are static. It appears like you just slide across the ground. Aircraft wheels should be like ground vehicle wheels that can be destroyed and can actually spin and move.

Edited September 7, 2013 by ProGamer

[RushHour 11]

A couple of more meters would be nice actually, as proven it is possible to take off but it´s just barely possible, and with some semi-unrealistic momentum carrying out on the runway.

Or cut down some trees :) Or why not an airbrake or something, i´m sure planes have this right? Build up the power then let go of the brake and get a nice acceleration.

[progamer 14]

Barely got out of that one, we should thank the bushes for not being physical.

But it´s great to so see someone doing it, seems like you need to get some momentum there in the beginning which is the key to just barely having enough speed to produce lift.

I have, this is what my video is showing, it´s only X all the way down.

But the drag/accelleration/speed is wrong though. Most drag equals slowest acceleration and top speed.

Do you get the same numbers if you start up the game again?

A couple of more meters would be nice actually, as proven it is possible to take off but it´s just barely possible, and with some semi-unrealistic momentum carrying out on the runway.

Or cut down some trees :) Or why not an airbrake or something, i´m sure planes have this right? Build up the power then let go of the brake and get a nice acceleration.

I like the challenge of the runway. I did see something about the first runway on Altis was for an RC club though.

[Sarlac 1]

I have managed to take off from that north western airfield. It was tricky but it worked. It requires using every inch of the runway and rotating at the last second before crossing the road at the end. Only a very slight nose up attitude will work. You will just barely clear the trees and the farm house but it can be done.

[RushHour 11]

Yea i think that if we get sort of a brake on the jet we could take of more easily. Basically build up the power then release it and get a better boost down the runway.

That way you don´t have to come with momentum and barely miss trees etc.

I´m very excited to see how an STOL transport plane would take of and land there. Probably feel like it defies physics a bit i think :)

[zedderzulu 7]

Yea i think that if we get sort of a brake on the jet we could take of more easily. Basically build up the power then release it and get a better boost down the runway.

Agreed! In theory it shouldn't be too much of an ask to add the parking brake feature from the road vehicles to the aircraft. Building up engine power before releasing the brake is a fairly standard way of any aircraft taking off IIRC.

Also perhaps slightly hijacking the thread but I've noticed that the AI makes no attempts to take off or land at the grassport in the hills or down in the south-east. That strikes me as a bug rather than the AI thinking things through realistically because a) it's fairly easy to take off and land from the south-east strip and b) in previous titles I've had much fun watching AI futilely try and take off from strips that are too short.

Also, though it's likely far too late to mention it now, but I wish they could come up with a slightly more complex/versatile taxing system for AI. At the main base they just land and taxi down the second runway - as it were - and just stop at the end. Getting light aircraft to park themselves in hangars with big aircraft parking outside the terminal might just be a bit of a stretch, but the decade-old system they use can be used creatively. I remember back with Tonal the BAS guys had a wonderful system when aircraft would actually turn into the pavement outside the terminal and park facing back out towards the runway. I experimented with it myself when I did some wrp tinkering for my own use. Can be done, but probably not a high priority concern for the devs...

Though getting the AI to use at least the southeastern airstrip would be welcome. Lots of potential for a mission featuring a high-profile target from Pyrgos or whatever-the-capital's-name-is using the airport for a quick insertion or extraction. :)

So we just need the AI to be able to use it... oh and some transport aircraft too...