Flight model and other early impressions

I thought I'd share this video from AcroGimp as it's really interesting and I didn't see it on the Yak forum. Maybe I just missed it.

Yep, you missed it….https://forums.eagle.ru/showthread.php?t=217781

Indeed! Thanks for linking the correct thread ;)

Spin behavior, use of aileron in the spin and forward stick authority has greatly improved with todays patch :)

E.g. One can enter an inverted spin from inverted level flight now.

Really? What about flap drag? Have they fixed that one?

I don't think so. Still can't get here to accelerate above 160km/h in level flight.

This is not enough to climb with the flaps extended, neither for the German manual go-around (160km/h) and even less so for the go-around procedure in the English manual (170km/h)

edit: ground adjustable trim tabs still don't work.

In-Spin aileron as I recall causes a slight flattening, Out-Spin aileron significantly accelerates the rate of rotation and flattens the spin as well. This is called an Aggravated Spin and I demonstrate one in a video I linked on my Advanced Spins thread.

 

'Gimp

Hey John ... the in-spin aileron IRL seems cause additional 'flicks' during the spin... it's really uncomfortable! It kind of ends up as a hybrid 'flick' and spin, and it's not a constant rotation... sort of jerks you about, surging during the spin. But as with everything except flat-spins, she's a pussycat to deal with! :) I only discovered because I was teaching someone and they had introduced some aileron and I was trying to figure out why the spin didn't feel right!

A.

I just finally got around to booting up my DCS computer and will be giving this module a go... I know Konstantin has been involved and helping out with this and real word data, so I've got high hopes they'll get everything solved and ironed out. He's vastly experienced in yaks!

So... my experience... I have over 1000 hours on the Yak 52 and every flight continue to learn.

Seen a couple of comments about the flaps/drag and speed vs RPM. it is VERY draggy. Generally speaking, you're at 82% when the flaps come down, and only go to 100% on final. Try being at 82%, it still requires a lot of power (remember power is throttle/manifold pressure, not RPM). There is a huge pitch up moment when they come down and the speed washes of REALLY quickly with the drag. It's tough to maintain 170 until you start coming downhill. I will maintain 170 for most of final to give me a little extra energy and bleed that back as you get to the threshold. The 52 glides like a brick, and it gives you an extra couple of seconds to figure things out before speed hits 150 for the glide if the engine stops. (There is nothing wrong with the correct procedure of being at 150, just like the energy, personally). Down hill you should maintain 170 no problem.

On the go-round ... forget it... you MUST retract the flaps early or you aren't going anywhere. Gear can wait till you're positive rate up... remembering that it'll sink a little as you retract the flaps (hence leave gear down!). It'll easily accelerate to 170 then (another good reason to be at 170 already on final... #justsayin).

Will let you know what I find in the module. Excited to play!!! :)

Spin behavior, use of aileron in the spin and forward stick authority has greatly improved with todays patch :)

E.g. One can enter an inverted spin from inverted level flight now.

BTW - if you're looking at a normal (Erect or Inverted) spin in the 52... never use aileron. Rudder and elevator is all that's needed... and actually... with application of rudder and even relaxing the pull (or push) it'll come out of the spin probably before you get to neutral let alone full spin recovery.

Flat spins are different... into spin aileron is used to break the plane of the spin along with full elevator deflection and I was also taught to use full power. The rate of rotation will increase just before it breaks... and you need to centralize very quickly afterwards or it'll quickly flip the other way (inverted or erect) to how it started... nasty! Personally I don't ever practice or teach these cos I'm a wimp and I fix it at the warning signs before it develops, I learned and practiced it before, don't intend to do it again!

I'll leave that to people with bigger balls than me. (At least I'm honest!)... 'Gimp over to you on that! ... incidentally peeps... you should know that 'Gimp deserve mucho respect... he's the only person I know that does the crazy stuff he does with only one leg ... Kudos John ... see you soon.

1. if you're looking at a normal (Erect or Inverted) spin in the 52... never use aileron

 

2. Seen a couple of comments about the flaps/drag and speed vs RPM. it is VERY draggy. Generally speaking, you're at 82% when the flaps come down, and only go to 100% on final. Try being at 82%, it still requires a lot of power (remember power is throttle/manifold pressure, not RPM). There is a huge pitch up moment when they come down and the speed washes of REALLY quickly with the drag. It's tough to maintain 170 until you start coming downhill...

 

3.On the go-round ... forget it... you MUST retract the flaps early or you aren't going anywhere.

As I mentioned a few times before. Ask 2 pilots about a single airplane and you get 3 different answers ;)

1. I only mentioned this because it did look wrong to me that opposite aileron while maintaining full pro spin rudder and full up elevator did cause the Yak-52 to stop spinning.

2. That's pretty close to what we are having now, but quite a bit different what AcroGimp and the manual says.

3. This doesn't match the procedure from the German and the English manual at all.

As I mentioned a few times before. Ask 2 pilots about a single airplane and you get 3 different answers ;)

 

1. I only mentioned this because it did look wrong to me that opposite aileron while maintaining full pro spin rudder and full up elevator did cause the Yak-52 to stop spinning.

 

2. That's pretty close to what we are having now, but quite a bit different what AcroGimp and the manual says.

 

3. This doesn't match the procedure from the German and the English manual at all.

1. Ah - I see the mistake... Don't maintain pro spin rudder - that's not part of the recovery.

a) Traditional FULL Spin Recovery (which works for a 52, but is overkill) is:

Close the Throttle and check height (in case you should just abandon); check needle; apply opposite rudder; move control column centrally forward (or as appropriate).

b) Abbreviated for an aircraft like the 52... cos it generally stops instantly... check needle, opposite rudder, control column centrally forward (or as appropriate). In the 52, a stab on the opposite rudder and bringing the control column to neutral is usually enough however to stop the spin instantly and in the incipient stages just easing the pressure is enough to stop it flicking.

2. I just finally got to play with the module; the aircraft is a little more slippery generally than the real one. The Yak is pretty speed stable but it really doesn't accelerate as well IRL; consequently it maintained 170 downhill a little TOO easily and the flare is a little too abrupt. I'll try and get some video footage next time I fly.

3. I'll look at the manual at some point and see where it differs and get back to you... Sometimes it's about semantics and lessons learned. Pretty much every aircraft though... power & pitch, then flaps quickly, then gear. If you're in a multi-stage flap aircraft (unlike the 52), then you'll get rid of the drag flap stages immediately and leave the lift flap stages, then take the gear on positive climb, then clean up the remaining flap in stages at safe altitudes and speeds. Remember you want to get rid of the biggest drag causing things as quickly as possible while still maintaining a viably flying (and usually climbing) aircraft. As you see downwind... the yak barely wants to fly level with the flaps down and shed loads of power... forget trying to climb!

<Anyone reading: I don't have time to type all the variations and combinations and situations so please don't jump on this explanation with specifics or cos I phrased something poorly... I am aware of them; this is a general rule>

More to come... Feel free to ask any questions/feedback and I'll try and back up answers with explanations and real videos where possible. I'm sure AcroGimp or Konstantin will do the same.

P.S. I'll see if it works in the sim, but generally speaking with the 52 ... any time she's about to bite you (incipient spin, flick, out of energy at any attitude, approach/entry into a flat spin as it starts to go)... just close the throttle and centralize everything. It might take a bit and it might be really uncomfortable waiting, but at worst she'll just flop her nose down and build speed up. Obviously on a flick cos you pulled too hard in a turn, that's a little bit of overkill, but you get the idea. It's the engine torque (often coupled with huge control inputs that makes her bite you!)

Prime time to get into a flat spin, that's not aggressive and will catch you unawares is to be trying to do a really tight pattern in the final turn... you're concentrating on the runway... don't look at your speed, get slow, use a little extra rudder with the higher bank for a tight turn, carrying power cos of the drag... and.... ....

BTW - if you're looking at a normal (Erect or Inverted) spin in the 52... never use aileron. Rudder and elevator is all that's needed... and actually... with application of rudder and even relaxing the pull (or push) it'll come out of the spin probably before you get to neutral let alone full spin recovery.

 

Flat spins are different... into spin aileron is used to break the plane of the spin along with full elevator deflection and I was also taught to use full power. The rate of rotation will increase just before it breaks... and you need to centralize very quickly afterwards or it'll quickly flip the other way (inverted or erect) to how it started... nasty! Personally I don't ever practice or teach these cos I'm a wimp and I fix it at the warning signs before it develops, I learned and practiced it before, don't intend to do it again!

I'll leave that to people with bigger balls than me. (At least I'm honest!)... 'Gimp over to you on that! ... incidentally peeps... you should know that 'Gimp deserve mucho respect... he's the only person I know that does the crazy stuff he does with only one leg ... Kudos John ... see you soon.

Gennady doesn't teach aileron for any spin recovery, DOSAAF focuses on min height loss, I'll try a little in-spin during a flat next time I focus on spins.

We'll have to do some DCS MP form acro when you have time, maybe real world too.

'Gimp

It's absolutely invaluable to have real and even more important, active Yak-52 pilots on this forum!

This amount of experience with Yo-Yos ability should make the DCS Yak-52 easily the most precise simulated airplane ever!

Concerning the GA. The German manual says:

1. level off and increase power, (watch out for the pitch up moment with power increase and the right turning tendency)

2. Increase speed to 160km/h

3. Start climbing

4. Retract the gear

5. between 70-80m retract the flaps

6. continue climbing at 170km/h

edit: the GA procedure in the DCS Yak-52 manual is identical, expect for the first item, the 'level off'.

Reading the English GA part again it says:

1. Set T/O power

2. accelerate to 170km/h

3. retract the gear

4. at a positive ROC, retract the gear.

It nowhere says to increase the speed to 170km/h in level flight ;)

Yeah... that's wrong and bad airmanship in ANY event and most aircraft (incl the 52). Think about the logic .... you are low and slow, you need to get rid of the heavy drag... best to leave the gear until you're headed back up in a stable configuration. NEVER take the gear before flaps in any aircraft unless that aircraft's procedures specifically dictate - because if you sink, better to have the gear down to touch the ground/runway than the belly. As I said in previous post... in most multistage flap aircraft you get rid of the drag portion of flap and leave a little so you have the low speed lift, the aircraft will still sink a bit before it accelerates and becomes stable in the new config... then it'll start up... now you can take the gear... and progressively raise any remaining flap as speed and altitude increase

- and yes... you don't look for 170 in level flight necessarily on a go-round; but you look to climb at 170 so you do need to accelerate (which does mean prob not a full nose up attitude yet, and might by default mean that you are in about level flight so you're at least not descending both descriptions of that are reasonable). If you leave the flaps down, you might JUST about manage to climb, but you're more likely to hit 170 in level flight and not be able to climb at that! ;) ... and... you've just raised the gear in a positive rate... ok... well... now you're about to overspeed the flaps immediately after (as flap limit is 170 and you don't have the gear extra drag) and the Yak may not be in a positive rate of climb anymore (due to the lift from the flaps (albeit small) and the inherent nose down moment on flap retraction). It's hideous practice all around.

Like I say... if you're already at 170 for the approach, this makes the go round really simple, not to mention you have a second or two extra for the "WTF" moment if the engine stops! With all the drag out, fine pitch on the prop and that flat nose ... it slows down REALLY fast when you need to to; you can leave 170 till you're almost there and bleed it back to 150 when you're pretty certain you're going to land. Just like a jet, which is why they did it, it'll accelerate and decelerate on a line, so always point where you want to go and adjust power. Don't fly it like you would a Cessna, treat it like a jet

Something fun from our 2017 season, if you're interested...

Izzat You "Limey?"

If you leave the flaps down, you might JUST about manage to climb, but you're more likely to hit 170 in level flight and not be able to climb at that! ;) ... and... you've just raised the gear in a positive rate... ok... well... now you're about to overspeed the flaps immediately after (as flap limit is 170 and you don't have the gear extra drag)

Gear drag is another questionable item. With gear and flaps down I can barely maintain 165km/h in level flight.

Retracting the gear makes the speed slooowly creep up to 168-169km/h. Not even remotely able to overspeed the flaps.

Izzat You "Limey?"

Affirm ... Jay?!!

Gear drag is another questionable item. With gear and flaps down I can barely maintain 165km/h in level flight.

Retracting the gear makes the speed slooowly creep up to 168-169km/h. Not even remotely able to overspeed the flaps.

I'll try and get some video at power settings and density alts so you (and devs) can see the acceleration/drag/behavior. Obviously every Yak is different and a lot depends on the engine/prop too but at least it'll give a frame of reference.

Right now things I noticed... Roll rate is a bit fast, airframe is a bit slippery, bleed of energy in the vertical/g-loading is too high (and acceleration on the down/level is too fast), flap drag is maybe a little high (but pretty close; suspect they'll need to up the standard airframe drag and decrease the flap drag a bit)

Generally, if it's a normal day (not too high density alt) you're at 82% and full throttle; enter a loop at 300, pull to 4g... you'll come over the top at 150 and reach the bottom exactly as you went in (same alt, same speed).

About the estimation "by eyes" :) , for example, the roll rate

 

https://forums.eagle.ru/showthread.php?t=203148

 

There are a lot of perceptual factors that affects reality/simulator comparison, so...

Agreed... but... it's still a little fast! There is ONE yak I know of that rolls about that speed - and I'm unsure how it manages it! The other 20 or so I've flown def don't! :)

Konstantin is awesome and possibly his yak is one of the lucky ones! Incidentally please note that it rolls at a very different rate between left and right!

Also - please note I'm not complaining ... is an awesome job... just want to help make it perfect! (As I'm also going to do with the early jets... vampire, venom, meteor etc!)

I'll try and get some video at power settings and density alts so you (and devs) can see the acceleration/drag/behavior. Obviously every Yak is different and a lot depends on the engine/prop too but at least it'll give a frame of reference.

 

Right now things I noticed... Roll rate is a bit fast, airframe is a bit slippery, bleed of energy in the vertical/g-loading is too high (and acceleration on the down/level is too fast), flap drag is maybe a little high (but pretty close; suspect they'll need to up the standard airframe drag and decrease the flap drag a bit)

 

Generally, if it's a normal day (not too high density alt) you're at 82% and full throttle; enter a loop at 300, pull to 4g... you'll come over the top at 150 and reach the bottom exactly as you went in (same alt, same speed).

The odd thing is the airplane should not be be BOTH too draggy and too clean, but that is the behavior observed, the model accelerates too fast on the downline and decelerates too fast on the upline. Also agree on roll rate for slow rolls - need to do a few more but I think the snap rolls might be a little slow but the barrel tendency with the nose seems about right.

'Gimp

Affirm ... Jay?!!

Yepper... :thumbup:

That sounds great Yo-Yo ... really ... awesome work, this will be an amazing piece of modelling when you're finished with the refinements - it is well on its way already.