I've not tested the Spit 1, but I do have a video of me breaking the wing of a Spit IIa recovering from a 430mph dive (which is as fast as I could get her to dive), with full (/ almost full) elevator and rudder deflection.

Let me know if you'd like me to upload it.

I'll try the Spit 1 soon.

I would say it's quite the opposite. So are the reports of my fellow Squadmates flying 109s exclusively. I'd say it's much less stable now and not as responsive as it used to be. They have definitely tinkered with the imput sensitivity, it took me a while to get used to it, but no, the 109E is not easy to spin.

You can break a wing of a Spitfire doing just what you described.

No, I am afraid they are absolutely not. :(

I lost my starboard wing last night in a steep dive on the ATAG Server, but did not note the airspeed at that moment -- obviously 420 mph IAS or more. But both your observations and Crumpp's point to some further tweaking on that aspect of the Spit's DM.

@Crumpp -- I agree that something serious should have broken (or at least bent) with a hard "assymmetrical" (is that the right term? Dunno!) pullout such as you did. Did you black out during the pullout? My reason for asking is that other threads are noting that full control surface deflection is not being achieved with the Spitfire under random circumstances. That would've resulted in a gentler pullout than you had intended, provided you had enough altitude to recover. But if you did experience blackout in the pullout that would be a fair indicator that the elevator was indeed doing its job as you intended -- and something should've gone crunch IMHO. (I've crunched lotsa virtual Spits and Hurries in Cliffs of Dover LOL).

Quote:
Originally Posted by Crumpp
"I have not examined any of the FM's in any detail since I got the game. I just noted how easy it was to spin the Bf-109E ..."

Robo replied:
"I would say it's quite the opposite. So are the reports of my fellow Squadmates flying 109s exclusively. I'd say it's much less stable now and not as responsive as it used to be. They have definitely tinkered with the imput sensitivity, it took me a while to get used to it, but no, the 109E is not easy to spin. "


Hmmm, I think your observations actually coincide. I believe Crumpp is simply referring to incipient spin occurring upon accelerated stall -- which is apparently happening too easily and viciously (for a 109) since the latest patch. Maybe I'm wrong, but that was my impression. :)

Just now I tested a spit 1, dive at 400mph indicated and I pulled back as hard as possible, with a full rudder. Nothing broke, and my pilot blacked out momentarily. Although at 430mph dive, I broke the spit 2a wing.

It seems to me the limit is between 400 and 430mph (taking both variants to be roughly equivalent.)

I made videos of both. happy to distribute the track file if necessary for proof.

LOL, Not really...that test would be a death sentence in a real aircraft.

It was a simple test. If you are above ~238mph EAS you should be able to break the airframe in a Spitfire Mk I with a single axis load.

By assymetrically loading the airframe, that speed is greatly reduced. The airframe should turn to confetti.

A dive over 300 mph EAS at full control deflection with an assymetrical load is pretty definative and easy to do.

It started too as I reached the top of the apex of the loop. It did not black out though.

Are there V-n diagrams for these aircraft available online anywhere?

That is it.

LE slats are the aerodynamic equivilent of training wheels. Putting them at the wing tips like the Bf-109 does not do much for raising anything more than the section co-efficient of lift but it does keep the ailerons responsive, make for very good stall characteristics, and it is one of the best anti-spin devices a designer can use.

The stall characteristics of the Bf-109 are very gentle, controllable, and offers plenty of warning:

http://kurfurst.org/Tactical_trials/...ls/Morgan.html

Not that I am aware of but you can easily make one.

Yeah, but I'm moving across the country in a week, so I don't really have the time at the moment :cool:

Can anyone else see those brains working from here!! lol

Well if everyone is complaining that all the aircraft are 25-30 mph off in terms of level speed, it is probably the environment.

First of all, it will be the summer of 1940. The density altitude is much greater than a standard day on a warm summer day.

Almost all of the performance data quoted by folks defending their favorite airplane is performance on a standard day.

At a higher density altitude, you will see a reduction in Indicated Airspeeds and climb rates. That is normal atmospheric effects.

It does not mean the game is modeled wrong.

If Maddox games really models things correctly, it will be very funny to listen to people. Players will be screaming when they hit their boost override and increase rpm over maximum continuous or 1.42ata, or whatever high power/high rpm system their game shape has only to watch the airplane slow down on that hot summer day!

:grin:

what are the equivalent EAS numbers for the 109? similar?

Regrettably, that is not the problem at all.

Camber's post earlier in this thread highlights the actual cause for concern by the virtual RAF pilots:
http://forum.1cpublishing.eu/showpos...4&postcount=56

Regarding G modelling and Structural strength etc, I don't believe its modelled in CLOD .... it should be.

Look, I don't want to piss people off or alienate them.

That post does not show an issue at all. He is comparing apples and oranges by using the FTH on a standard day with the performance on a non-standard day.

FTH at 5000 meter is the FTH at pressure altitude or a STANDARD DAY.

What I mean by that is on a 95 F day, at 29.45inHg, and a 67 F dew point spread, when you are at 5000 Meters True altitude the airplane is at 6992 Meters Density altitude.

In otherwords, when you are standing at sea level on that day, it is the exact same as being at almost 1000 meters in the air on a standard day.

Soooooo, why does the 109 E4 match the STANDARD DAY data at 5000 meters, but the Spitfire Ia and IIa are woefully short at 16,500 ft and 13,500 ft respectively?

Under what data are you looking at? What data are you using for these aircraft.

Are you looking at Indicated airspeed, TAS,..????

By my calculations, the Hurricane for example is within 2% of its data for a standard day. Whether that is optimistic or pessimestic depends on the weight of the aircraft in CLoD.

From the link I supplied you, these are actual in-sim trials conducted by Camber first on the 109 E4, then on the Spitfire Mark Ia, then on the Spitfire Mark IIa. I don't know how to make this any clearer to you -- this is a simple copy & paste from that link:

EDIT: It occurred to me that perhaps a clarification is in order here. What you may not have understood is that a number of us, including Camber below, have been checking the actual in-simulation performance of the aircraft in question to the charts posted by 1C. Under the test conditions in the simulation, the 109 E4 closely matched the STANDARD DAY performance charts (as they should), but the actual in-simulation trials of the Spitfire Ia and the Spitfire IIa did not! These two aircraft performed -- in the sim -- well under the mark that Luthier says they should.

Default weights of each aircraft with fuel at 100% were used.

I can speak from personal online experience on the ATAG Server that many of the air combats that take place are close run things. Even a 10 kmh difference in speed between two aircraft in combat can mean the difference between drawing enough lead or not, or holding a climb just long enough to tag the opposing player -- or not. Each player in this sim continually refines their ACM and engine management techniques to eke out just 1 more mph at the crucial moment. Those who have flown with me or against me know of what I speak. So these numbers below -- taken from that link I had provided you earlier, are not just numbers on a graph to us. We look at them as likely meaning the difference between success or failure of our online endeavours. Hence the passion and hence the scrutiny. Many of us on the Red (virtual RAF) side know there is something very, very wrong with what's happening on this sim. The numbers that Camber has posted, which mirror those that others, including myself, have tested bear out our misgivings.

So, hopefully in a new light, I present again Camber's in-simulation findings:

Camber said:

Quote:

I calculate TAS as 2% greater than IAS per 1000ft altitude using this link (http://www.csgnetwork.com/tasinfocalc.html), there may be a more accurate calculation out there.

I just did some altitude speed tests offline (beta patch), they are OK for 109 but a bit horrifying for the RAF as they are below the B6 patch curves. I tested for full Throttle height (above which boost declines at full throttle). My assumption was that top TAS should be around FTH.

109E4 (prop pitch control on)

FTH: 5000m (boost has dropped a bit to 1.32ata, declines rapidly above 5000m)

425kmh IAS@5000m = 569kmh TAS, exactly right for Messerchmitt official average spec.

Spit Ia

FTH = 16500 ft
at 6.25psi, 2750rpm (rad open) engine fails after about 3 minutes. Just enough time to get stable 245mph IAS (with 3000rpm couldn't get this alt without engine death)

245mph IAS@16500ft = 323mph TAS = 520 kmh TAS

Oh dear, this is under even B6 plot speed (560kmh TAS at 16500ft).

Spit IIa

FTH = 13500 ft (?!)
at 6.25psi, 2750rpm (rad open) engine fails after about 3 mins

260mph IAS@13500 = 328mph TAS = 528 kmh TAS

I really hope I making some kind of testing error here. Tried online and got same values. I wouldn't feel confident taking any Spit against 109s at alt with these values.

camber
Last edited by camber; Today at 03:17 AM.

LOL that's why I said in a previous life.

The trouble with testing at this stage of dev is there is little to no difference in performance with hings like fuel loads low/full, radiator open closed. In a dog fight it is for most of us hard to get max performance out of ac due to work load.

I for one (il2-46) when diving into a fight would close radiators for speed but open them if things didn't go to plan after a min or so in fear of cooking the engine from forgetting to check gauge. Prop pitch radiators and war power usage were as important to surviving as maneuvering.

Now prop pitch and throttle gate are the only things to think about. In a fight I tend to feather the throttle a lot and don't often use full throttle for long. When flying the spit I tend to leave the gate in place as the damage to the engine you get with it open is not IMHO worth the small gain. But that's it. It's not that hard any more. So the gap between novice, vet and ace has lessened.

What Snapper says :idea: Don't get me wrong, the game is still fun to fly, but it can not be called realistic or a 'sim' until they fix the performance issues and untile they incorporate things like radiator drag, open canopy drag, sort out the weight issues, high alt flight behaviour etc. The problem is not -25% for every plane, they simply got the FMs wrong. Some more, some less, but we're currently not flying BoB aircraft.

Regarding the Bf 109E stall, I had this problem when I first applied the patch, but then I did the trick described by DavidRed (deleting the confuser.ini file), reseting my controls settings effectively - voila, no violent stalls, still unstable and different rudder response to what it was prior to the alpha patch. I feel it has something to do with the input sensitivity changes (same with Spitfire throttle or all rudder axes). It just took me a while to get used to it. I will fly more in the coming days and I will report back if I am wrong.

I agree... and FM's trustworthiness is really easy to check... Can we talk about DMs?
If the FMs are crap and the overall sim is a mess are we sure that the DMs are correct? Above all then we don't have an SDK to test it with precision.

Really I don't understand how many of you can actually have fun... I have a total of 34 hours on CloD, and most of them are been spent to configure the settings and test the server functions.

That is realistic and one reason why automation was an advantage in WWII aircraft.

+1.

Max TAS for the Spit1a occurs closer to 22000 feet, not 16500.

The Spit 1a is faster than the 109 above ~6000 meters.

Have you actually tested that, Doggles?

Does the sim even work above 6000 meters (19685 feet)?

Yep, some intrepid souls have made it to 27,000 feet, but I never have. Even at 6000 meters I find myself singing this song over and over and over.......

http://www.youtube.com/watch?v=UEaKX...e_gdata_player

Snapper, I thought you'd only starred in the film 'Dogs of Dover'!

How did you land that role? :lol:

I myself had the Spit II up to 28,900ft the other night on ATAG server 1. God I must've been bored.

It just wouldn't go the last 1100ft to 30,000, no matter how hard I tried. It was a nice view though.

Here's a couple of shots. Didn't take one of the view, unfortunately. :(

20/22k is ok, you can go higher to around 24K for sweeps but rarely see anything else at that alt, Wolverine and maybe one or two others. Not much point in going any higher.

But it's so rhoenry way up there....... :(

Yes. Spit 1's climbed up into my E4 seemingly effortlessly at 7000 metres not too long ago.

Well, there's rock solid, indisputable proof beyond all doubt.

:-)

*shrug* If you want to stick your fingers in your ears and go LA LA LA then that's up to you.

I went up to 7k, closed rads most of the way, leveled out, and hit full throttle. Three Spit 1s who were below and far behind me eventually caught up.

I think that's pretty definitive. Incidentally, it agrees with this graph that Banks prepared from the graphs posted by 1C staff:

https://docs.google.com/spreadsheet/...x=40gk54utfx7r

I note with much amusement that Snapper, you posted in this very thread less than 10 posts after this post was made, yet you act like you haven't seen it.

But again, if you want to pretend that the 109 is superior in every aspect to all the RAF fighters then go ahead.

Yes high up it was alright for the RAF pre-patch and I assume it's the same now. I suggest you try flying the RAF for couple of weeks to see what they're trying to tell you.

Hey, you've got no argument from me. Thanks to you, I've seen the light!

http://m.youtube.com/watch?v=hnTmBjk-M0c

Apologies for posting this in the turn rate thread...

That is my original testing data Snapper was quoting. My concern was that Spits don't conform to the B6 stated performance (which is what Banks plotted).

For Spit Ia (offline, 0900 game time) I get:

FTH = 16500 ft
at full throttle, 6.2psi, 2750rpm (rad open) 245 mph IAS
245mph IAS@16500ft = 323mph TAS

At 19500 ft
at full throttle, 4psi, 2750 rpm (rad open), 230mph IAS
230mph IAS@19500ft = 317mph TAS

Max speed drops above sim tested FTH (16500ft) as would be expected. My Spit I is slower at alt than 109s and B6 data. Simple IAS/TAS conversion (2% rule).

rpms>2700 give rapid oil gasket failures during these tests.

camber

make a vid?

Perhaps I will in the future but I'm too busy the next month or so... plus I'm not sure my rig can handle FRAPS and still run the game at playable levels.

Damnit Crumpp said much the same thing :) It's like doing the dishes

I don't think it's impossible that (as you say) that Spits and 109s are speed competitive at high alt. Whose to say that the in-flight gauges are actually giving correct information? We could have a Spit 1a and 109 at 20000ft with gauge data showing the 109 20% faster, but both the aircraft actually doing 100mph TAS (or 500mph TAS!) through the CloD air.

At this point it just gets confusing. For any aircraft, mismatched discussions can occur based on any combination of:

* Performance calculated from gauges
* Developer stated target performance
* Actual relative performance in game
* Wishful thinking relative performance in game (hopefully not too much of this :))
* Optimistic historical performance
* Pessimistic historical performance
* Fantasy historical performance (hopefully not too much of this :))

For me I think it is time to give up for now and just have fun with what it is and whatever it becomes.

camber

Don't worry there will be plenty of that once the Mustang makes an appearance (and to a lesser extent the fw190).

There's really no conclusions to be drawn until we know what the atmospheric conditions are as modelled in the sim, and until they fix the shoddy state of the current flight model.

Once we have that we can run test flights, correct the data to standard conditions, and use that to compare to historical data.

I have had maybe three encounters with lone BFs at 20K+ co alt (with this beta patch) which ended with the BF109 disengaging or not resulting in a clear advantage for either as long as I maintained my alt and not give a guns opportunity during convergence.

Those encounters tended to be less aggressive with more separation, sort of plugging away untill someone makes an error so to speak, and if neither make a mistake the encounter can go on for some considerable time. I have no idea who the players were or their skill level.

A real dogfight. Just think about having a wingman in that moment.

I climbed a Spitfire Mk I. It was difficult to trim the aircraft as the stability was pretty much nuetral on the longitudinal axis.

I felt like the oil temperature was high from the begining. The aircraft started the channel free flight at the limit of 90 degrees. I had to have the radiator open in level flight at 4 1/2lbs @ 2800 rpm. The Operating Notes tell the pilot to close the radiator in level flight and open it on climb only if needed.

The rpm changes were rather dramatic too. A small control input caused large deflections in the rpm making it difficult to smoothly and precisely change.

I did not check FTH or anything, just getting a feel for the aircraft.

I dove to 420IAS and did manage to lose an aileron but still could perform and full deflection assymetrical pullout. The pullout again resulted in a loop with some grayout at the top but no blackout.

and then there is the G.50....trimming it to fly high is a joke.

Down low at full bore you have to close the radiators because it's over cooling

up high though...it's almost overheating

Do you find the climbrate correct?

Yes, with current Fm it is impossible to follow the manual regarding the temperatures. You will find yourself flying with the radiator fully open at most of the times. I will bother you none as the drag is not modelled, but still. You schould be able to climb at manual settings with the radiator 1/2 closed at 160mph IAS, fully opened rad will cause more drag and less climbing speed = more heat. Does not work this way in the sim I am afraid.

Above certain altitude (12-13k pre-patch), the coolant temperature will become the one to watch more. Unfortunately, you will not be able to fly at full power at FTH to compare your speed with the historical test data - as that will overheat and ruin your engine. Mixture does not work properly. And you have got wrong fuel. But othervise, everything is OK.

It was always a bit awkward and sensitive, but you can get used to it after a while and set the RPM quite precisely. What bothers me more post-patch is the throttle axis response. Did you not find it difficult to set the boost? It was alright in the previous patch, I am not sure what have they done to it.

Great stuff, do more testing please and let us know what you think.

Structural damage is not modelled yet for any aircraft. It should be though. All that happens is you will lose parts of your ac that ou will miss later. As for blackout, try to trim tail heavy while pullout. I remember blacking out at few occasions while turning at high speed. I have no experience with diving as it was a bad idea trying to outdive a 109 in this sim. All I remember was to keep my speed within limit when attacking bombers (manoevrablility limit that is, not structural).

this broadly concurs with my experience. I made a 430IAS dive, broke the wingtip on the pull-out and was no longer able to maintain level flight as a result (roll input).

But the aircraft was flyable.

What ??? You can drop flaps on a Spit to improve turn performance ??? Seriously ??? That flap is the least efficient flap in the game, needed more for drag, pitch adjustment and ground effect than lift.

So, yet another example showing that to play the game well one should throw reality out the window and learn the game planes. (fun, tho)

My thoughts and my thoughts alone.

Unfortunately some bad things from IL2.1 were transfered to IL2.2

well it is curious that those flaps on the spit do that. You are right, they are pretty inefficient flaps, non adjustable, and they drop to a super low angle which in reality should cause a heap of drag

So interesting, really like it

The Spit flaps at least optically seem correct. They were only landing flaps and there was no way to put them on an intermediate level (which was wrongly modelled in IL2 1946 ). AFAIK, for the seafires, they placed a sort of stopper to fix the flap temporarly to an intermediate level for take off from carriers. As soon as the flaps were retracted the stoppers fell off and gone the possibility to have the flaps on an intermediate level.

You are right, the issue has been reported already: http://www.il2bugtracker.com/issues/91

Just for the record, the flaps have been sorted in 1946 already in one of the later DT patches.

The spitfires using wooden wedge were normal mk.Vs starting from a carrier. Destination: Malta.

An excerpt from AVIA 6/2422 "Notes on the turning performance of the Spitfire as affected by Altitude and Flaps"

The only comment I would make is that the full doc discusses the fact that only "Flap 85" (Down) is selectable so the intermediate settings and any values discussed are by estimate/calculation. The values in the table are Sustained turn performance ... without Height loss.

http://i40.photobucket.com/albums/e2...urnwitflap.jpg

Excellent! :) Does the report mention the turn time/radii at SL perhaps..?

Unfortunately no its all 12,000ft and up.

Ahw. :/ I wonder if its possible to convert the figures to different altitudes..?

Good stuff IvanK, only thing that confuses me is the 'Merlin XX', i guess that's a typo of some sort, or was that some Mk.III testing?

Good information regarding Spitfire flaps down behaviour at page 11 of this document:

http://ntrs.nasa.gov/archive/nasa/ca...1993092582.pdf

There is a Pencil Note on the first page next to the title "MKIII". This I presume is an annotation to indicate that the document is based on the spitfire MKIII which would also match the XX Merlin. A weird choice of variant to do tests with !

Got the NACA report.

You have the entire report?

I am sure it does not say lower 85 degrees of flap and fly around in small circles.

Yes

It is not hard to do at all. We can use the first entry for flaps up turn performance at 12000 feet.

V = TAS/SMOE = EAS

Standard Means of Evaluation at 12,000 feet = 1.2011

Flaps up TAS at 12,000 feet = 160 mph TAS

160/1.2011 = 133 mph EAS

133 mph EAS * .869 = 115.6 KEAS

Oh check it out....They give you EAS on the report. Gee, wasn't that another 100 page discussion on these forums?

Anyway, once you have EAS you can easily convert the performance to any atmospheric condition you want.

I like working with BGS but the units do not matter. Just don't put the correction factors like "1091" and "11.26" if you are using metric and keep your units straight.

Our formula becomes:

Radius = (VKeas * SMOE)^2 / 11.26tan <theta>

<theta> = angle of bank which is a fixed relationship with load factor irregardless of altitude

If you use the above formula and knots, our radius calculates out to be 693 feet and the RAE measurement is 695 feet. Pretty good agreement.


Radius is not the primary turn characteristic in a fighter. It not so important how small the circle but how fast we can bring the nose around to put guns on target.

So lets check our rate of turn based on the document:

Flaps up = 160 TAS * .869 = 139 KTAS

1091(tan 68 ) / 139 KTAS = 19.42 degrees a second

360/19.42 = 18.56 seconds to complete a 360 degree turn

18.6 and 18.56 are a match....

Now let's see what it does at 20000 feet:

160 TAS at 12000 feet = 133 mph EAS


133 mph EAS * .869 = 115.6 KTAS

SMOE @ 20000 feet from our Standard Atmospheric Data = 1.3700

Radius = (VKeas * SMOE)^2 / 11.26tan <theta>

Radius = {115.6*1.3700}^2 / 11.26tan <68>

= 899.97 or just 900 feet @ 20,000 feet

Rate = 1091(tan 68 ) / (115.6KEAS*1.3700)

= 17.05 degrees a second

= 360/17.05 = 21 seconds to complete a 360 degree turn at 20,000 feet

Here are 3 Relevant Fan plots from the report posted without comment

Clean:
http://i40.photobucket.com/albums/e2...an_cln-sml.jpg

Flap 30
http://i40.photobucket.com/albums/e2..._flp30_sml.jpg

Flap 60 and Full at 85.

http://i40.photobucket.com/albums/e2...p60-85_sml.jpg

Do you have the conclusions stated in the report and the conditions?

It appears the RAE contradicts the NACA's findings on the effect of flaps on turn performance as well as what is taught in modern curriculum's.

I really don't think that is the case and I bet that agreement is in the details of the report you posted.

I understand your reluctance to share those details in this report. I would be happy to provide you the NACA findings on this subject.

As you yourself said there have been many 100 page discussions about your use of EAS to estimate turn performance in the forums you post in and it seems that you still have not mastered the art.;-)

The way you simply use EAS above to derive results for 20,000 ft gives erroneous results that bear no relation to actual performance of the Spitfire at this altitude and a more realistic turn time under these conditions would be about 30 to 31 s.

We are not going to do another 100 pager because you lack formal education in aerodynamics.

EAS is the most common expression for velocity in all aircraft performance calculation. It is the preferred expression because it is so simple to use.

It is too easy to convert to TAS any performance derived with EAS and you don't have worry about density effects in the mechanics of the calculation. Just convert at the end.

It also a great approximation of Indicated Airspeed and very easy to convert to that with a PEC chart and a universal compressibility.

http://img856.imageshack.us/img856/4475/easspeed.jpg


http://www.google.com/url?sa=t&rct=j...o9yenlVuG8g5Zw

http://img826.imageshack.us/img826/1055/easagain.png

http://img526.imageshack.us/img526/5828/easinturn.jpg

http://img854.imageshack.us/img854/6...areduction.jpg

If you are trying to quickly gauge relative performance you don't have to convert back to TAS. The specific numbers for rate and radius will change in proportion to density ratio which is a universal application.

TAS is what is used in the calculation. You don't even recognize it, LOL.

:rolleyes:

the conclusion if you can really call it that is covered in the intro summary and the endpapers:

http://i40.photobucket.com/albums/e2...4/summary1.jpg

http://i40.photobucket.com/albums/e215/zulu64/conc3.jpg

Crumpp I presume you are referring to these NACA documents:

http://i40.photobucket.com/albums/e2...64/nacaflp.jpg

http://i40.photobucket.com/albums/e2...4/Naca2flp.jpg

If so I have them. The RAE report is quoted as a source or reference in these NACA reports. In addition the first one also references the other RAE report "Notes on the dogfight"

All three documents are imo in general agreement. The Devs should study these ! "Combat" flap usage in the classic IL2 imo was totally out of whack with reality ... sadly I am not so sure much has changed in CLOD.

Right, for some reason people tend to think of flaps as a magical aid to turn performance and a crutch for poor ADM.

They are of very limited use in maneuvering to the average pilot.

I think the NACA conclusion in ACR #222 sum it up the best. In general flaps can offer some turn performance improvements beyond the clean configuration stall point but not above it.

In order to realize that improvement, a pilot must be able to precisely deploy the exact amount of flap required at the optimum speed to achieve that benefit.

IIRC, the example they use is 130 mph and 127mph....

That small speed difference with the right amount of flaps realizes a turn performance increase but the same amount of flaps at just 3 mph slower speed results in worse turn performance.

Additionally, that report is "pie in the sky".

The Spitfire had only two flap positions, fully retracted and fully extended.

0 degrees or 85 degrees...the pilot can make his choice!!

:grin:

Ivan, would you be willing to provide a download link to those two reports, or else attach them to a PM?

Pretty please? :grin:

here...

They do mention that specifically in the report.

I presume the reason for the original RAE report was to decide whether manouevring flaps would be useful for existing designs and how they could be used in future. I doubt whether the original Spitfire flaps would have been strong enough to have been used at medium-high speeds, even if they had been adjustable. It is interesting to note that the Spitfire IV (later XII) Griffon engine prototype DP845 (first flight 27 November 1941) originally had reinforced slotted flaps with external guides, so possibly this alternative design was mooted as a result of the tests on the Spitfire III, which was very similar, apart from the engine.

Outstanding. Thanks very much.

LOL, the RAE even have an EAS on scale on their fan plot.

:rolleyes:

Now if only the Spitfire had Fowler flaps .....

The problem is that your turn time of 21 s at 20,000ft is physically impossible. No amount of posturing and posting irrelevant book quotes underlined in red will change that fact:

You have claimed R=900 ft turn radius and turn time T=21 s at 20,000 ft:

Since I'm a metrics guy I will convert R to SI units, i.e. 274.3 m

This gives a turn speed of 82.08 m/s (2*pi*R/T)

So from this we calculate the turn acceleration: a=v**2/R=24.56 m/s**2

So load factor is n= sqrt(a**2+g**2)/g=2.696

Let's calculate the Cl this would require:

n*m*g=0.5*ra*v**2*Cl*S

Spitfire data:

W=6000lb=2724 Kg
S=242 sqft=22.36 m**2
ra=0.65 (Approx at 6.1 Km alt)

Solving for Cl:

CL=(2.696*2724*9.81)/(0.5*0.65*82.08**2*22.36)=1.47

Now NACA claims Clmax for the Spitfire at 1.2 which is a bit low but according to RAE it is 1.36 tops. Your claim leads to a Cl of 1.47 which is clearly unrealistic and like you fails the sanity check.

BTW: I found a RAE report, R&M 2349, Notes on the turning performance of the Spitfire as affected by altitude and flaps.

On page 4 there is a figure 4 which gives the following results for the Spitfire at 20,000 ft: R=1045 ft and T=31.5 s

With my C++ simulations I get R=337 m (1106 ft) and T=31.65 s.

You claim 21 s turn time and 900 ft radius of turn. I get 31.65 s and 1106 ft while Morgan & Morris in R&M get 1045 ft and 31.5 s.

So on the one hand we have C++ simulation data and the data from the RAE report R&M 2349 which seems to tally and on the other hand we have your overbearing attitude and simplistic calculations leading to an off the chart Clmax. What could be the right number I wonder , 21 or 31 s?

Finally, I think the only thing we actually agree on is the other parties lack of formal aerodynamic training. We have been down this road before and as I've told you before I have an Mcs in aeronautical engineering from the Royal Institute of Technology in Stockholm from 1986 and more than 10 years in the business working in the defense industry for Ericsson and SAAB on the Viggen and Gripen fighter systems.

Tell me, What aeronautical companies have you worked with and the Msc in aeronautics from Embry-Riddle you claim to have, which year did you graduate and was that before or after your stint in US Special Forces?;)

Math is good. Me likes math.

:grin:

Me too. In fact, my favourite snakes are adders!

133 mph EAS * .869 = 115.6 KTAS

SMOE @ 20000 feet from our Standard Atmospheric Data = 1.3700

Radius = (VKeas * SMOE)^2 / 11.26tan <theta>

Radius = {115.6*1.3700}^2 / 11.26tan <68>

= 899.97 or just 900 feet @ 20,000 feet

Rate = 1091(tan 68 ) / (115.6KEAS*1.3700)

= 17.05 degrees a second

= 360/17.05 = 21 seconds to complete a 360 degree turn at 20,000 feet


http://img717.imageshack.us/img717/2...erformance.jpg

115.6*1.3700 = 158.4 KTAS

Looks like 21s when we ask the US Navy or use any universal turn performance chart!!

Ha ha ha :eek:

:grin:

The output is only as good as the input...

Yes Holtzauge, I am employed full time in aviation as a pilot.

Yes, I retired from the US Army before I went into aviation as a second career.

How about you? You do C+++++ simulations for a living?

;)

:rolleyes:

http://img819.imageshack.us/img819/4...rnwitflap1.jpg

Anyhow, CL, CD or Cwhatever values mean absolutely NOTHING if reference surface (and reference length for couple of forces) is unknown. Anybody with basic notions in aerodynamics should know this. I can announce CL values of 1700 for a brick if I just select a reference surface small enough if I wish to do so and nobody could claim me wrong.

The CL values in this report are only interesting in relative terms with respect to different flap angles.

Another interesting fact about basic aerodynamics. Coefficient of lift is independent of altitude and corresponds to an specific angle of attack.

In otherwords, the angle of attack for best turn performance will be the same no matter what the altitude.

Amazing that some simple calculations reflect that basic fact. OHH the INSANITY OF IT ALL!!!

All you calculate here is the turn times at constant KEAS and constant g load (2.68 g which corresponds angle of bank 68 deg) at two altitudes, 12k and 20k. Then you claim that an airplane which can do this kind of sustained turn at 12k, can do sustained turn at same g load at 20k at same given KEAS. Note that your calculation does not account the engine power and the power might be different at 12k than at 20k.

Now, think this for a minute instead insult the other members of the board.

Mh. IIRC CL does depend on Mach number even at subsonic speeds and thus indirectly on altitude as for the same IAS the Mach number changes with altitude, the speed of sound being intimately linked to temperature.

It's not fair. I see all of the math but I still can't shoot anybody down =(

I don't like math.

Yes it does but the RAE was using subsonic incompressible flow theory in that report.

In subsonic incompressible theory, Coefficient of Lift is independent of altitude and mach number.

A compressibility correction to velocity is used to account for it.

In the formulation, compressibility is factored in when converting from CAS to EAS.

http://www.thedailyatpl.com/atpl/per/how-does-the-lift-coefficient-for-maximum-range-vary-with-altitude-no-compressibility-effects/

That certainly depends on which merlin and which variant we are discussing. I don't know as only snippets of the report have been posted and would only be guessing.

If you read the thread, the question was how to convert that performance to other altitudes.

The answer to that is to use the EAS scale provided in the RAE chart and convert to what ever density altitude you wish.

On the first page it says 'Merlin II Spitfire'.

So, what's the point of your calculation then? You did not quess any power value but claim a time, 21 sec for 360deg, for sustained turn at 20k which is unrealistic given that power is lower at 20k than at 12k (Merlin II).

The scale does not matter, EAS or TAS, it's just slightly different calculation.

While your work looks ok to me, I think the original question's intent was "can we convert this data to see what the a/c would be capable of at higher altitudes" which is not answered by the math you posted. Rather, we would need to check available power at the relevant altitude.

Is the question asked and I answered.

http://forum.1cpublishing.eu/showpos...&postcount=166

My post was not a treatsie on specific aircraft performance.

It took a few seconds to say, "Yes you can use EAS to convert the performance to any altitude" with any airplane.

And did the correct mathmatical mechanics to show the process to change altitudes given a speed and angle of bank.

As for the other baloney posted, it will always reach CLmax at the lift line irregardless of altitude in the theory the RAE is using.

That should not be a surprise to a MSc Aerospace Engineering.

Any undergraduate who has taken a Basic Aerodynamics course understands that. It is a principle of subsonic incompressible flow theory.

This document was written around the Spitfire MKIII (never went into production only prototype stage) powered by the Merlin XX. All the data tables and graphs refere to merlin XX equipped aircraft.

There is a single Reference to Merlin II spitfire on the first page.

http://img688.imageshack.us/img688/4786/raeeas.jpg

The reason why the RAE provided the EAS scale is to quickly convert to different altitudes and conditions.

Crazy Huh??