Jump to content

Archived

This topic is now archived and is closed to further replies.

thepitts

Can you get a plane to spin?

Recommended Posts

What prompted the question was the underwhelmed sensation I personally got from a recent “aerobatic plane” release and a not quite so recent Russian “aerobatic plane” release. Yes both these models are brimming with eye-candy but brimming with flight modelling characteristics I am not so sure. In particular “super critical” behaviour re stalls, wing drops, spins +ve / -ve and flick rolls.Now it may be that it is unrealistic to expect modelling in these areas of flight (and I definatly don’t want the canned FSX versions). I heard (please correct if wrong) that x-plane 9 models up to 24 aoa. I suspect that if correct that a “plugin” to compensate could end up dwarfing the original programme! Does x-plane 10 model spins for instance? Or do you know of any x-plane 9 models that will spin (and hopefully recover) with the subtly of modelling that x-plane can potential give to aircraft in the normal flight envelope range? TIM

Share this post


Link to post
Share on other sites

I don't think that flight models in either sim are good enough for a proper spin. A common uncoordinated stall should spin the plane, but will not.


PPL ASEL

Working on IR

Share this post


Link to post
Share on other sites
Guest bstolle

Not correct. There are quite a few planes in FSX already that do spin correctly. E.g. the Seabee I'm presently working on has the same spin entry and spin behaviour like the real one.FSX is very flexible and you can finetune a lot of details concerning the spin e.g .attitude, rotation rate, entry etc...

Share this post


Link to post
Share on other sites
Not correct. There are quite a few planes in FSX already that do spin correctly. E.g. the Seabee I'm presently working on has the same spin entry and spin behaviour like the real one.FSX is very flexible and you can finetune a lot of details concerning the spin e.g .attitude, rotation rate, entry etc...
Cool bstolle, I havn't flown th Seabee. I'm going off my experience with other add-on planes (Carenado, Flight1, etc...) Thanx

PPL ASEL

Working on IR

Share this post


Link to post
Share on other sites

For fsx, the a2a cub with accusim is noted to be good for spins.


Rob

Sim rig: Intel Core i9 9900K @ 5GHz, Asus ROG Maximus XI Code, MSI 2080 Ti, GSkill DDR4 32 GB, NZXT Kraken. 

Current sims: P3D v5, MSFS, X-plane 11, Aerofly FS2 and DCS. 

 xdQCeNi.jpg   puHyX98.jpg

"There are three simple rules for making a smooth landing. Unfortunately, no one knows what they are."

Share this post


Link to post
Share on other sites

As we all know, the aerodynamics of a spin are pretty complicated from an airflow perspective if not a conceptual perspective. X-Plane doesn't really have the numerical resolution to calculate the forces to induce and maintain a spin on a reasonable level. I say reasonable because I had taken it upon myself a while back to see if I could get plane to model spin behavior and had limited success where I could stall the plane in a nose high attitude, let go of the stick and the plane would enter a spin for about 2-3 revolutions before coming out of it, but doing so required some pretty off the wall tricks that pretty much abandoned accuracy in other flight regimes. Just getting it to spin "hands off" for 2-3 times was a success enough for me to not pursue it any further though as my goal was to mimic the dynamics of a spin numerically, if for only a instant. Just because a plane might "rotate" a few times while pointing down or will "spin" if you hold the joystick over constantly doesn't mean it's spinning. My goal was to get the wings to stall at different rates and actually have differing lift /drag values and let the gyroscopic effect keep it spinning...and analyzing the numbers, I managed to get it to happen but didn't pursue it with any more vigor.It is my guess that x-plane could be made to perform "better" than what you are experiencing with your aerobatic aircraft purchases but I think true simulation of spins is beyond x-plane's ability (or any affordable sim) and getting it to model spins, even approximately, without forsaking other areas of performance is a delicate high wire act that just might not be practical. There is still some room for investigation though by intrepid souls who wish to test the fringes of x-plane's abilities but to be honest, I think individuals with an understanding of not only aerodynamics, but also numerical methods and modeling are not very common in the flight sim market.I think perhaps your description of "super-critical" says it best as there's a darn good reason it's called that.

Share this post


Link to post
Share on other sites

Thanks TKyler I thought as much. No problem what it does model (with the the help of decent developers) is excellent.For the FSX crowd..... if you think that FSX/ FS9 can model spins well......errhh I am very happy for you!

Share this post


Link to post
Share on other sites
Guest bstolle
For the FSX crowd..... if you think that FSX/ FS9 can model spins well......errhh I am very happy for you!
Thank you :(

Share this post


Link to post
Share on other sites
For the FSX crowd..... if you think that FSX/ FS9 can model spins well......errhh I am very happy for you!
For starters, If you've been up spinning the real life Pitts, enough times................then why are you upset if a desktop sim doesn't exactly replicate the particular spin characteristics & proper recovery for the particular plane model? I say plane model...........because as we (who have done spins) know, that there are recovery options that vary....... with different aircraft.As far as I'm concerned, basic spin recovery is worth practicing on a desktop, because it can be memorized. Note: basic recovery can easily be looked up on the net. Slight changes in technique can also be easily looked up on the net.As to the models in FSX, I still very much disagree about the term "canned" that you frequently use. I too, have done many real life spins in a Pitt's, including inverted. And that goes for snap rolls, hammerheads, tailslides, and many other aerobatic manuvers. There are some aircraft for FSX that are capable of replicating the motion of spins, inverted spins, secondary stall/spins, and accelerated stalls. These are far from "canned" since the recovery can be put into effect at any time..........using realistic recovery methods. Of course these simulated spins are not perfect, and I don't expect them to be. Yet the motion, fact that airspeed doesn't increase, and the fact that recovery imputs change the outcome..........in real time, without delay, make these artificial spins more benificial to the sim than not.BTW---- It would be a good idea for an aerobatic X-Plane to spin. Seems like a few X-Planes have been able to spin in version 9. I just don't remember which ones.L.Adamson

Share this post


Link to post
Share on other sites

So much to discuss so little time. Let’s take it one point at a time shall we. (“For starters, If you've been up spinning the real life Pitts, enough times................then why are you upset if a desktop sim doesn't exactly replicate the particular spin characteristics & proper recovery for the particular plane model?”) ----mmhh well not really that upset but thanks for your concern. Practice practice practice. I use simulators part for enjoyment part training. Having a simulator that could give a believable representation of supercritical manoeuvring would further extend the training potential of the software. Hopefully that answers the “Why”. Personally speaking you can never do it enough times and that extends to spinning. (“...........because as we (who have done spins) know”) ---- understood that you are personally experienced in this area. Unfortunately my personal experience in supercritical manoeuvring is limited to C-152, Yak 52, Bulldog, Robin2160i, Slingsby T67, Pitts S1, Pitts S2, (“Note: basic recovery can easily be looked up on the net. Slight changes in technique can also be easily looked up on the net.”) ----Easy to look up yes. Easy to sift the wheat from the chaff definitely not. Dear punters be very very very wary of information on the web. Not that there isn’t some good but there is an awful lot of CR*P. In my opinion your best sources for information on recovery of aerobatic types are the relevant chapters in Alan Cassidy’s aerobatic bible ”Better Aerobatics” ; Eric Muller’s “Fight Unlimited” and John Denker’s “See How it Flies”. (“As to the models in FSX, I still very much disagree about the term "canned" that you frequently use”) ---now we’ve been here before haven’t we (go on you know we have) (“I'll address this topic a bit more.”You don’t need to.I personally have had this particular discussion with you at length in the recent past in which we politely and respectfully disagreed. No problem. Like you I keep an open mind I am not a zealot for any particular sim (and Fly did have its moments not least bringing PMDG into existence)... It’s all an illusion.We are both extremely privileged to have been able to fly these wonderful aeroplanes. Many simmers unfortunately are not and fulfill their dream of flight through computer simulations. When someone quotes their real world experience in part to justify their remarks I always like to step in (much like yourself) if I feel differently; just to give other simmers a broader view.You with your experience feel that MFSF can provide you with an illusion of supercritical manoeuvres.I with my experience...don’t. Simple.It’s all a case of balance”) And that only 17 days ago... time flies when you’re having fun. It’s a pity that x-plane can’t realistically model this but I understand why.If you and Bstolle feel that the look up table approach to this regime gives you a believable experience I am happy for you in your world. In my world they don’t they just feel canned. TIM

Share this post


Link to post
Share on other sites
What prompted the question was the underwhelmed sensation I personally got from a recent “aerobatic plane” release and a not quite so recent Russian “aerobatic plane” release. Yes both these models are brimming with eye-candy but brimming with flight modelling characteristics I am not so sure. In particular “super critical” behaviour re stalls, wing drops, spins +ve / -ve and flick rolls.Now it may be that it is unrealistic to expect modelling in these areas of flight (and I definatly don’t want the canned FSX versions). I heard (please correct if wrong) that x-plane 9 models up to 24 aoa. I suspect that if correct that a “plugin” to compensate could end up dwarfing the original programme! Does x-plane 10 model spins for instance? Or do you know of any x-plane 9 models that will spin (and hopefully recover) with the subtly of modelling that x-plane can potential give to aircraft in the normal flight envelope range?TIM
Hi Tim,actually X-Plane airfoils model lift, drag and moment in the full +/-180 degrees range, not only 24 degrees. With Airfoil-maker you can only modify the first 20/30 degrees or so (don't remember exactly the value), but hand-editing the airfoil file with a simple text editor, you have access to the full 360 degrees. AFAIK, this is rarely done by developers though.Another thing I'd like to add is, X-Plane flight model used to lack a term in the core equations of motions, the so-called "cross-inertia" term, that takes part in the dynamics of spin and high AoA maneuvers. I personally discovered this and reported it to Austin exactly five years ago, now according to Austin it's finally been corrected in X-Plane 10. :)That being said, I don't know if there are currently aircrafts that can realistically model spin in X-Plane 10.

"The problem with quotes on the Internet is that it is hard to verify their authenticity." [Abraham Lincoln]

Share this post


Link to post
Share on other sites
Guest bstolle
Unfortunately my personal experience in supercritical manoeuvring is limited to C-152, Yak 52, Bulldog, Robin2160i, Slingsby T67, Pitts S1, Pitts S2,You with your experience feel that MFSF can provide you with an illusion of supercritical manoeuvres.If you and Bstolle feel that the look up table approach to this regime gives you a believable experience I am happy for you in your world. In my world they don’t they just feel canned.
Never heard or read about 'supercritical maneuvering' in context with slow subsonic airfoils and/or lightweight aerobatic planes.Where does that come from? Neither 'advanced aerobatics' (Szurovy/Goulian) nor 'aerobatics' (Williams) etc.. mention this term.Feeling canned? If a real 152 drops into the same spin with the same entry everytime....isn't that kind of canned as well?

Share this post


Link to post
Share on other sites

Murmur:--- very very interesting. I'd have to say you are losing me rapidly ("cross-inertia" terms within the core equations of motion). I could hazard a guess at what you are talking about but would properly be deluding myself. Anyway really interesting information. So non-canned spins maybe a possibility in the future.bstolle:--- super(above) critical (refering to critical AOA)..... terminology first introduced to me by a Russian DOSAAF instructor working in the UK (an excellent aerobatic pilot and true gentleman.) " Neither 'advanced aerobatics' (Szurovy/Goulian) nor 'aerobatics' (Williams) etc.. mention this term"---good books but now superceded. If your interested would highly recommend.the ones I refered to.TIM

Share this post


Link to post
Share on other sites
----Easy to look up yes. Easy to sift the wheat from the chaff definitely not. Dear punters be very very very wary of information on the web. Not that there isn’t some good but there is an awful lot of CR*P. In my opinion your best sources for information on recovery of aerobatic types are the relevant chapters in Alan Cassidy’s aerobatic bible ”Better Aerobatics” ; Eric Muller’s “Fight Unlimited” and John Denker’s “See How it Flies”.
I'm not going to sit and read through these books for aerobatic "basics". Actually, in the past, I may have read some of them, or portions. I don't remember, and it doesn't matter. Unless these books have references to specific airplanes, regarding stall, spin characteristics, and recovery............................then I'll go for actual test data which is readily available on the internet. I don't need blanket generalizations, when specifics are there for the reading.L.Adamson

Share this post


Link to post
Share on other sites

  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
  • Donation Goals

    AVSIM's 2020 Fundraising Goal

    Donate to our annual general fundraising goal. This donation keeps our doors open and providing you service 24 x 7 x 365. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. We reset this goal every new year for the following year's goal.


    42%
    $10,690.00 of $25,000.00 Donate Now
×
×
  • Create New...