So what have you done to make your game controller act like the real control column?

Well the pilots did note the same issues the NACA recorded.

for example, in the prototype:

From Handling trials of the Spitfire K.5054

Keep in mind, he made absolutely NO MEASUREMENTS but this is all opinion from watching the ratio of blue and green out of the windshield, LOL.

http://www.spitfireperformance.com/k5054.html



http://img705.imageshack.us/img705/4...yexplained.jpg

http://www.spitfireperformance.com/k9787-fuel.html

Oh yes blame engineers for making an aircraft safe, I mean who would want an aircraft to stay in the air I would much rather have it crash into my garden shed :rolleyes:

Were not in a debate over safety here, it's about combat pilots finding a characteristic they enjoyed about an aircraft being neutered because of some officious pen pushing graph monkeys not being satisfied with measured results.

I personally have no gripes with the spanner monkeys and like to keep a good rapport with the engineers in my company, things actually get fixed when you are nice to them.

Given K5054 was the prototype is it not fairly obvious that any reports made during testing were likely acted on? but to suggest it took 3 years to address a stability problem with the production types is really stretching feasability don't you think?

Fixed that for ya

In that based on my 20 some years of being an engineer

I can tell you that 'most' seasoned engineers have a 'if it ain't broke don't fix it' approach..

Typically it is only the young and or student and or academic types of engineers that 'feel the need' to fix things that are not broken! ;)

Not when Operating Notes are full of symptoms of instability, the test pilots continue to report the symptoms of instability, the pilot anecdotes convey the symptoms of instability, and an independent aeronautical research organization confirms the issue.

Oh yeah, the engineering solution to the issue was also enacted AFTER the Battle of Britain:


http://img254.imageshack.us/img254/6...htelevator.jpg

No, I don't think it is stretching feasibility at all.

It is one of the facts that helped Gates to win the adoption of stability and control standards in the UK during the post war period.

The same engineering experience that led to your discovery of the creation of energy in airplane performance a few years ago, Tagert?

Sadly some have an 'if I can't find the fault it ain't broke' attitude too.

It's interesting that all tested aircraft displayed longitudinal dynamic instability. Thought so based on the tests I've seen, but never before heard this summary. Good to know for certain.

OTOH I think it is a pity what has become of this topic in the last 48 hours.

True.. As noted, those working towards a degree (students) love to fix things that aint broke.. Than there are the bored types of engineers who are trying to justify thier existance.. There is no absolute rule in that human nature will win out in most cases.. Sadly as in this case/thread some 'feel the need' to say something needed fixing that the pilots themselfs didn't think needed fixing.. Human nature! ;)

Typical non-technical attitude. Doesn't understand something so he just brushes it off as irrelevant. Real men don't need math, right bongo?

If you don't understand it, then stay out of the discussion.

Operating notes with a 'few' refferences to instability much like many other types of the era you mean.
pilot annecdotes are acceptable now then?....but just not the ones with anything positive to say on the Spit?
and NACA independently tested a MkV which is a totally different aircraft in terms of weight and balance.

Do they give out awards for hypocrisy? you must have a stack of them now.

Where does this come from??

:confused:

It is patently false as a generalization.

While many WWII fighters were unstable in very specific conditions such as in climb power with a specific speed range or landing configuration.... most were stable and met the requirements.

It is was very rare for a design to be unacceptable over the range of the envelope such as the Spitfire.

Read page 18 of the NACA report and note the conclusion of satisfactory for short period oscilations (remember they were the ones that really counted)
and was noted as satisfactory for stick force gradient appart from 'flaps down power on', page 19 is good reading too.
Then try to show your :rolleyes: smug face here again when you realise you have been completely discredited.

http://jsbsim.sourceforge.net/spit_flying.pdf a link to the report

Ah, yes, i remember now. I vote against it, because that issue strongly related to the stick movement, design and forces. You flying in RL, i don't have to say, in RL you have much more feedback from the plane, plus you have 1:1 sized, smooth force feedback stick ;) You feel the plane movement, shaking, the forces on the seat, etc.
I dont think, it would be possible flying with a plane, which requires such a feedbacks, but the user able to fly with a non FF, crappy, 15cm high plastic toy. I mean, we're reach the limits of the PC games with it. No matter, how accurate game you want, it lacks the equipments, G forces, butt-forces :D

So true :(

Which requirements were there for long period dynamic longitudinal stability?

And this is the million dollar question, even Crumpps NACA 'bible' states that long period stability was not looked in to much as it is of no particular consequence....so it seems the much maligned Spitfire failed 'slightly' in a characteristic of little to no significance, in summary it can be asumed they used a basic rule of stability is beter than instability in this regard so they gave the Spit an 'F' and Crumpp something to cling to.

The requirements are set out in NACA Report No.755. By R. R. Gilruth

I posted a link to it a couple of pages back.

EDIT:http://aerade.cranfield.ac.uk/ara/19...report-755.pdf

So, suddenly the Spitfire was unacceptable over the range of the envelope? I take it this includes stalling behaviour:
http://i91.photobucket.com/albums/k3...-page-003a.jpg

http://i91.photobucket.com/albums/k3...-page-004a.jpg

And because the Spitfire was so unacceptable over the range of the envelope NACA, and the engineer who compiled the report, later singled it out as being an example of a badly designed fighter that made all the rest look good:

http://i91.photobucket.com/albums/k3...-page-001a.jpg

http://i91.photobucket.com/albums/k3...-page-001a.jpg

Presumably these bad flight characteristics over the entire envelope meant that the poor sods called pilots hated flying the thing and couldn't wait to get out of the cockpit, shaking and drenched in sweat.

Totally agree.

There's nothing about long period dynamic longitudinal stability in there, hence my question.

:rolleyes:

http://img10.imageshack.us/img10/561...estability.jpg

But once again you have to adress the question. Where does it say it was a danger, a major problem or even a minor problem?

Right, there are not a "big deal" because they can be controlled by the pilot.

Hence the reason why inertial weights are added to increase his feel and ability to control those oscillations.

Right now, in the GAME, there is nothing for a Spitfire Pilot to control. The instability does not exist in the GAME.

http://img705.imageshack.us/img705/4...yexplained.jpg

http://www.spitfireperformance.com/k9787-fuel.html

In the game, they are longitudinally stable both static and dynamic:

http://img692.imageshack.us/img692/4...ctlongstab.jpg


You still trim the plane in the game without all the feedback a real pilot gets and you don't need FF for trim!

:grin:

This has been covered over and over. You know the answer and can read the POH.

Would you mind to continue the stability discussion in this thread:

http://forum.1cpublishing.eu/showthr...=33245&page=94


so we could continue discussing the general performance of the spit in the recent patch that is speed, overheating and climb?

Some people are interested in these issues.

Facepalm!!!!!

Double facepalm!!!! practically the primary function of trim is to aleviate the pilot from holding constant stick force thereby remedying fatigue....how does this not involve feedback?

Basically you right, but I'm sure, you cannot trim the plane as fast and accurate like in RL. When i fly with bombers, it is difficult to set the level flight. I trim the plane, and look whether moving or not. If so, I trim again, and look again, and so on. Disturbing that I don't feel the movement of the plane, or the stick forces.

And the trimm is not required such a precise handing, like the stick when you flying on the edge.

Too true, Crumpp can continue with his Spitfire elevator fetish on his own time - his bug tracker has gotten nowhere and he just wants to re-litigate this non-issue by hijacking this thread.

Has anyone got the engine data in the Spitfire I and Hurricane I Pilot's Notes?

I do know what they say and I do believe the fact that in a high speed stall the aircraft will bang and clatter is a really serious issue.
I mean what else would you expect to happen in a high speed stall? As a CFI you must have done dozens of high speed stalls and I am willing to bet that they clatter and shudder as well.

In a high speed dive it is possible to exceed the G limit, if you pull up too quickly. Well thats new, again as a CFI you must warn your pupils about the dangers of exceeding G limits, well I hope you do.

Great loss of hight when you lose control. Well thats novel. In the UK its normal to teach spins at 12,000 ft because of the danger of loss of height. I assume you do the same in the USA for the same reason. If not what height do you start spin training at?

The need to ensure that you have sufficient speed before recovering drom a dive. Well thats standard training and one that I hope you do as a CFI

Last but not least the fact that if you are so slow off the mark as not to take remedial action should the aircraft flick over, it may result in the aircraft being strained or break it. If you don't take remedial action when entering a high speed roll/spin what do you think will happen?

I think that covers all the points that you raised. Can I ask you to point out which are unique to a Spitfire. I can say that all these points and more are covered in Glider Pilot training in the UK.

Or if they are unique to a Spitfire, can you say which you don't teach in your position as a CFI?

It does seem that British, German and Americans trials and manuals and pilots all highlight a pronounced sensitivity and instability in pitch for the Spitfire, David.

If you hdn't buried his point of view with your wall of text and insulting comments we might hve hd the opportunity to raise some interesting point. Do you know tht or are you tht much overdone?

The requirements for long period oscillation in highly maneuverable aircraft is the slope of the velocity change should not exceed .04 difference.

Do you need me to calculate it or can you compare the slope of a line on your own?

Transport catagory aircraft have a less restrictive stability requirement which require a period of 55 seconds.

You can trim the plane reasonable well in these games. It is not the same as actually triming an aircraft but is a very reasonable facsimile.

I am sure a reasonable facsimile of the Spitfire instability can be implemented allowing the aircraft FM's to have their historical performance numbers while maintaining status as equal dogfighters.

Glider,

Airplanes all have unique flying qualities and the Spitfire is no different.

One of the defining characteristics of the early mark Spitfire is the longitudinal instabilty.

Modeling an aircraft with the speed, climb, and turn performance of a Spitfire and stable would be overmodeled and not historically correct.

[loop]
red pilots complain about bad FMs in british planes

clod devs fix red FM planes

blue pilots complain about uber FMs in british planes

devs downgrade red FM planes

red pilots complain about bad FMs in british planes
[/loop]

:(

Red pilots complain about porked red fm's

Blue pilots just like t argue with red pilots

Devs fix red fm's

Blue pilots complain

Red pilots still complain aboud totally unfixed red fm's

Blue pilots just keep arguing and making up fiction about red fm's

Blue pilots forget that if they want better blue fm's they need to complain to the Devs instead of automatically arguing with reds.

Tomcat's right.

Every time a thread comes up that you guys don't like you just spam it with pages and pages of nonsense and trolling until it gets locked.

For some reason the moderators allow those bully tactics to continue, instead of banning the lot of you. I can't fathom why.

Maybe I wasn't clear enough, I was asking about the requirements that were there at the time.
Can you please name the source of the requirements you quoted?

You omitted:

devs create as near realistic FMs as possible
[exit loop]

Something I do not deny for a moment, and am more than happy to have in the sim.
In an earlier posting I did look at a number of points that had been raised and tried to find areas of agreement so the Developers would have something to work on and improve things while others were shall we say debated.

However the key point is to what degree was it a major problem. Clearly it was in the Mk V and the bob weights were installed. The fact that it was an approved mod to the Mk I in July 1941 after other approved mods including the change of engine to the Merlin 45 and addition of 20mm cannon point (to me anyway) that it became a problem after the additional weight of these and other changes.
The fact that the Spit was in service for approx 3 years before this change idicates that until this additional weight was added it wasn't a problem.

On this I agree. So you agree that the points you highlight are not dangers specific to a SPitfire?

History says otherwise..

And I say again.... if we were released he operating instructions and what has been modeled into these aircraft everyone here might have a valid point to prove, I'm sorry but until we get more of an understanding these posts are futile

Thread successfully hijacked ...

where are moderators?

You are correct, if they want us to take CoD seriously they should tell us what they think they have given us. But if we assume the devs are modelling the Spitfire MkI with normal military loads and CoG and that it is to be operated in accordance with the pilots notes (as far as is reasonable) then it is not performing properly. Neither is the Hurricane under the same terms. And I expect the 109s may not be right either from posts in here.

I don't see where 'History says otherwise' comes into this.

OK back on Pure Topic.

YES to the title and I voted YES. It ruins the game. We're getting sick of waiting. Does that help?

The vote collects the answer to the title. Discussion of why it ruins the game is inevitable.

I wouldnt say that.. I asked for this thread to stop pages ago but since then I have to be honest and read every post here..some good info being put up and a lot of stuff I didnt know much about.

Im still none the wiser as to who is right or wrong here hence why i keep suggesting the read me/opertain instructions from the devs

Im revering to an old abused and tired subject about a FM that was put upon us before...I wont drag it all up here, I was just refering to that, was all

The danger to a spitfire in game should be that if a pilot abuses his controls (elevator) the plane should break up, the same abuse in a 109 shouldn't lead to breaking the plane, as the pilot there isn't able to produce the necessary stick forces.

The 109 pilot needs high speed and trim to break his plane with the elevators.

Just to keep it simple.

But this is nothing special about the Spitfire. Each aircraft has it's structural limits, exceeding these limits damages/destroys the aircraft. As you say the critical situations might be different for each aircraft.
The problem is not the Spitfire, the problem is that structural limits are not simulated.

How many Spitfires actually broke up in flight during the battle of Britain/ Documentary/damming evidence please (considering you want up to 80% of Spitfires to fall apart)?

Just for interest I'm going to post Bf 110 losses due to break up or other, mainly unknown, causes between July and December 1940:

http://i91.photobucket.com/albums/k3...-page-002a.jpg
http://i91.photobucket.com/albums/k3...-page-001a.jpg
http://i91.photobucket.com/albums/k3...-page-001a.jpg
http://i91.photobucket.com/albums/k3...-page-002a.jpg
http://i91.photobucket.com/albums/k3...-page-001a.jpg
http://i91.photobucket.com/albums/k3...-page-002a.jpg
http://i91.photobucket.com/albums/k3...-page-001a.jpg

According to Robtek in gameplay the wings should be theoretically ripped off Spitfires at least 80% of the time, with no empirical evidence that this actually happened in real life http://forum.1cpublishing.eu/showpos...&postcount=609.

So why not extend that type of thinking to other aircraft types, such as the Bf 110? Why not conclude that a large percentage of 110s lost in unknown circumstances were lost because of elevator failure due to mishandling? It could also be asked why did the 110 lose its right wing on the 18th of July? How many Bf 110s lost their wings, but were counted as lost due to unknown causes? Yes, let's make it simple and assume that at least 80% of Spitfires and Bf 110s will break up due to abuse of the elevators.

I don't think there's anything wrong with what robtek stated here, maybe he could have worded it a bit differently, avoiding the word abuse. The Spitfires elevator was sensitive enough to allow the pilot to achieve the stalling angle of attack at any speed, which at high speeds means it is easily possible to overload the airframe. So if folks in game pull back the stick all the way, they should either stall or break a wing. Just like it would have happened in real life. Pilots learned to not do it, hardly a big deal, and players can probably manage the same.

For the 109, this problem did not exist, the elevator was way too heavy at high speeds. There was, however, a different one. In high speed dives, there was a serious tendency for the nose to tuck under as speeds increased, and coupled with the heavy elevator, the pilot would not be able to pull out with the elevator alone. Trim had to be adjusted. This, however, lead to problems in the pullout, as speed decreased again the tuck under tendency disappeared, which meant quickly increasing g-loads up to the point where the airframe would be overloaded, unless the stick was pushed forward hard.

The problem that I have is that they didn't break up, there are hardly any examples of this happening.
I have said a number of times that I would expect to find a small number as their could be a number of reasons why an aircraft was weakened resulting in a break up but so far only one has been presented and so much happened to that aircraft before it broke up it was close to a miracle that it stayed together as long as it did.

Find some examples of it happening and we can debate it but without any them there is no reason to include it in the Sim.

That said I do reconfirm that if a pilot doesn't take remedial action almost immediately entering a high speed spin or roll then there should be a chance of break up. Any aircraft stands a chance of breaking up in those situations.

The poor bugger would probably be trapped by G forces even if the plane did hold together

I should add that the Me110 seems to have a much bigger problem than the Spit

I see we are back to the red vs blue tit for tat that doesnt help anyone. We dont need reliability modeled. When we fly we are almost garenteed 100% of the time to have action. If you see how many flights some aces took and the actual percentile of those that resulted in combat you can see that they flew far more non combat sorties than combat ones. We do need correct handling though.

I think finding the data and hashing it out as a respectable debate until we find a general consensus is the best for all. Lets leave our ego at the door and try to get the right evidence for such things and respect each other without emotion.

Yes we know the red pilots are very frustrated. All the flight models have problems and by and far the reds are most in need of urgent attention. However just arguing because you cant get you point through to somone on the net is not helping.

Thats an interesting doc NZtyphoon. Dont suppose you have one for 5./JG27?

There are plenty of examples.

Honesty, the whining about this issue has become legendary. Why are such a small group of people is such denial about a 60 year old airplane??

:confused:

An inertial elevator was added to the design.

Why would they do that???

The only reason to add such a device....IS TO INCREASE STICK FORCES IN ORDER TO OVER COME LONGITUDINAL INSTABILITY.

There is no other reason for it. Inertial elevator is the fix for only one thing...longitudinal instability.

Did other airplanes recieve inertial elevators? Of course, it was not invented by Supermarine despite the fact many seem to think of them as the wellspring of aviation. Other airplanes have stability and control issues that give them unique personalities.

All the tap-dancing and attempts to underplay that fact the Spitfire was longitudinally unstable in all conditions of flight at normal and aft CG are just not credible in any fashion.

Now the logic seems to be that if other airplanes had issues then the Spitfire get's a pass.

Why does it get a pass? Some people want to have the speed, climb, and turn performance in an overmodeled stable platform.

So what about the temperature issues with the spitfire? It seems that when temperature effects are turned off the spitfire is faster. Is this because when turning the temperature effects off the radiator no longer causes a drag (because it is closed anyway)?

Why does the water and oil not cool down when flying faster (for instance in a dive)?

Does the spit when flown by the books show temperatures and operation times as it should?

How about the speeds and climb that can be achieved?

It should be possible to reduce radiator opening in normal cruise. Is this implemented?

What about the mixture? It seems that when the lever is forward the game takes it as rich mixture.

+1
The Bf 110 data comes from Zerstörer: The Messerschmitt 110 and Its Units in 1940. There is a comprehensive book on JG27 available through Amazon but I'm wondering how it became a book on Sopwith Aircraft 1912-1920.

There are plenty, actually. Undue sensitivity of the controls and ease of overloading the aircraft structure is stressed as a specific problem with Spitfire in the Spitfire Pilot's manual.

Now is "hardly any examples of breakups happening" or "maybe you can a small number of breakups"? You contradicted yourself in the follow up paragraph, congratulations..

Of course there's a reason. I see the Spitfire manual specially noting the risk of breaking up of the airframe a perfect and throughly documented reason as to why include this control characteristic into the sim. Not much a 'debate' is required, its plain there.

I am sure our two import fanatics, Glider and NZTyphoon, neither of whom are actual players or buyers of the sim and are really just here to disagree and continue their old feuds from other boards and would like to bury the whole thing in another wall of nonsense. ;)

Wishful. You always seem have this stance, first denial, when denial no longer works, comes the 'oh maybe I admit I am sure the Germans had it worse'. What's the connection anyway to Jeffyboy's newest smokescreen about 110s...? I can count but one Bf 110 loosing a wing for whatever reason in this list of 6 months of losses. I am sure there were a couple others with similiar fate, but how does that connect the Spitfires?

Let me see if I got your "logic" right: one 110s lost a wing for some reason in July 1940, which is, Glider and Minorlinkstorian argues, a good reason why not to model Spitfire pilots ability to break the aircraft in two just by pulling the stick back too much, due to the well documented extreme sensitivity of the elevator, noted by NACA, RAE, the Air Ministry, and which was specifically noted in Spitfire Pilot's manual specifally notes for the type, and which was the cause of numerous Spitfire breaking up during the war.

Seriously, its way to transparent that its just two guys, arguing that their national idol should be modelled without any flaw in a WW2 flight sim. And I would say it's pretty lame to watch this happen in every thread.

Question.

One aircraft has a stick force gradient of 4 lbs/g, the other has a stick force gradient of 20lbs/g.

Question 1.
In which aircraft is it easier for the pilot to reach the actual break point of ca. 10-12 g?

Question 2.
Is it possible for the aircraft which has a stick force gradient of 4 lbs/g to actually reach that 10-12 g load at which the airframe is likely to break?

Wow,

ONE is due to inflight break up. The rest are due to other causes.

One is an outlier in a statistically insignificant sample, not to mention completely off topic of the British Flight Models.

Hey but emotionally it proves your point right? :rolleyes:

Post the paper's about the NACA's work, I think it time for that one again. It is pretty good at confusing people. You can write what ever you want at the top because folks don't read it and many don't understand what it says.

:rolleyes:

Getting back on topic of the British FM's.

This whole divide of "Red vs Blue" is totally idiotic and does not help the game in any way.

I don't support changing anything that changes the historical fact these aircraft were equal dogfighters. If they were NOT equal dogfighter, then the game should reflect that as well.

I don't want overmodeled ego inflaters for pre-teens pursuing nationalistic fantasy for any side.

I want all the aircraft modeled as accurately as possible. More importantly, I don't care about specific performance. I care about the immersion and thought process of the game.

Do I have to think like a World War II fighter pilot operating a state of the art piston engined fighter of the day?

That is the key parameter to success for the game to most people.

Unfortunately a few fans of specific aircraft ruin things for most by researching details to the point they can no longer see the big picture. Their vision becomes myopic and history is made to conform as a function some airplanes performance. :-)

All fair and good observations imho and should deserve their own bug ticket / thread.

They need to fix that Swift. You should be able to correctly operate the aircraft and produce the same performance.

Let's get some data and see.

I will check it out and post my results.

You can only stuff so much air in the radiator. In fact, most airplanes would get better performance with smaller intakes as they take in more air than they can really use for cooling!

Engine stress can create more heat than the cooling system can remove even at high speeds.

That is why if you descend at cruise power, your CHT's will exhibit very little change.

I have wondered if the Vx and Vy in the game is not off too. It is not hard to ball park the Vx/Vy from sawtooth climbs. I will run some calcs and confirm Vx/Vy.

I just saw Kurfurst post and I agree. Swift if you start a thread on it we will get the data for a bugtracker.

What Robtek says is absolutely correct.

This thread doesnt seem to be getting anywhere, we keep changing direction. We really need several threads - each for its specific problem, polite and respectful discussion and conclusion to present a bug ticket.

Then supply some

Again no one is denying that there was some instability and that from the Mk V onwards it was an issue that had to be resolved and was. I repeat again, that I personally do not have an issue with the instability as far as it exised in the BOB being modelled in the sim.

However, No one, absolutely no one, including you, has produced any evidence that it was a safety issue on the earlier marks during the BOB. No test report, no test pilot comments, no research establishment observations from any nation (including Germany) and the final proof, next to no accidents. Give us more than your theory as to what should happen and we can take it a stage further, but without some evidence all we have is your theory and that isn't close to good enough.

What also concerns me is that I did post a number of areas where I believe that we can agree on and use that to get the developers working on things that would improve the experience.
I strongly suggest that you spend a day looking at those proposals and we can all make some progress.

David, you do have the Spitfire Mark II manual as of summer 1940? What does it say on this topic?

The manual gives some precautionary advice that in no way give any indication the aircraft is dangerously unstable, rather it just reminds you that it can bite if 'mishandled', quite unsurprising for an aircraft of which the defining quality was manouverability.

I agree, but different people have different opinions about whats is 'realistic as possibel', which leads to an endless discussion...

Well, lets worry about that when they get even close.

Yes and there is nothing that seems exceptional.

Crumpp highlighted the parts of a Spitfire manual that caused him some concern and I addressed those individually and am more than willing to do the same for you.

Krump
You have also said that there are a number of cases of the Spitfire breaking up in the air and again I ask you to supply some examples. If we have examples we have smething to base the discussion on without them we don't.

A good place to start is Spitfire IIa on auto pilot posted 2 weeks ago - time= 1:27 and 1:59 show the Spitfire IIa's engine instruments 1:59 RPM = 3,000 Boost = +3 Oil Temp = 90° Coolant = 105°, radiator shutter closed: everything as it should be...

NZtyphoon:

AI uses different Fm and Dm...

Everyone else:

Or not... Im out.

Laughable.

NZtyphoon and his friends feel personally attacked, so they decide to bring out some 110 documents to "fight back" or "show them" or something. :confused::confused::confused::confused:

Talk about emotional investment. It's so blatantly obvious that I really can't help but laugh.

Start a different thread on the 110 if you like. Nobody feels threatened. If the data supports it I will happily lobby 1c for appropriate changes. I suspect that certain people here will continue to lobby for the changes they want (or to prevent the spitfire from being more realistic), regardless of whether or not the data supports them. When they are exposed as having no basis in fact, they will troll, spam and argue until the thread gets locked, just like they did the last time.

It's actually rather sad. This community really is one of the worst communities I've ever had the misfortune of being part of.

This is from Sydney Camm and the Hurricane describing the difference made when the Merlin changed from 100% glycol to 30% Glycol, 70% H20

http://i91.photobucket.com/albums/k3...IIMerlinXX.jpg

the lower operating temperature of the engine on this mix - also used by the Merlin XII - helped TBO and reliability. In theory the CLOD Merlin XII should not be overheating as much as it is right now. I'm not sure about the temperature difference of 70°C as quoted so I'll dig a little more.

Bf109 FM need fixes:

FM issues

Loss of energy/momentum
Bad climb rates
Incorrect top speeds
Incorrect acceleration.
Need faster Flaps moving out and in
Autopitch dont work correct


Bf110 FM need fixes:

FM issues

Engine overheating
Loss of energy/momentum
Bad climb rates
Incorrect top speeds
Incorrect acceleration
DM too weak
need better turn

Ju88 FM need fixes:

Engine overheating
Loss of energy/momentum
Bad climb rates
Incorrect top speeds
Incorrect acceleration
DM too weak
Need better turn


Ju87 need FM fixes:

Engine overheating
Loss of energy/momentum
Bad climb rates
Incorrect top speeds
Incorrect acceleration
DM too weak

Sorry, but without data which values should have to be corrected how and why this is just a whine post.

@Ossi: there is no loss of "energy momentum" in the 109 or 110 that I know about. IMOHO it's even the contrary with a more friendly behavior modeled to get more fun out of it I believe (109).

Your expectations might be too high.

Of course the S*** is another story but as we can only whisper after her in this place I won't even mention it.
:cool:

@Typhoon: Your extract mention the Merlin XX. It's up to you to conclude there is a link with the Merlin XII. Wonder if it is that way that you found evidences of the 100 oct being used. :rolleyes:

Pure Glycol has about twice the boiling point of water but only about half the heat capacity (plus its an anti-freeze). So in effect the coolant (and engine!) temperatures are going to be much higher (since the coolant agent can carry away about half the heat), but I reckon it would boil much later. Hence why it is used in a mix with water. It would also explain why the Hurri I and Spit I overheats so fast.

Engine temperatures are a function of coolant capacity, coolant type, coolant circulation capacity and heat transfer capacity of the radiators. The amount of pressurization the cooling system also raises the boiling point.

What was the coolant capacity of the Spit and Hurri Mark Is, how many gallons/liters? Are there any cooling trials available for these aircraft?

Well the manual highlights that the elevator is so sensitive that the pilot can easily pull enough g-load to exceed the structural limitations and of the aircraft. It isn't so in the sim, no matter how crazy manouveres I tried in the Spit (ie. vertical dives at Vne) I simply couldn't break it.

It's incorrect and the stick/pitch behaviour should be fixed.

Also the aircraft seem to be rolling much faster at high speed than it should - 3 times as fast as I recall.

Personally I think this disharmony between the controls and senstitivity in pitch are one of the most curious ommitments from the Spitfire's FM. Simply to put, it is not flown like a Spitfire, 'with a light fingertip on the elevator and arm wrestling the ailerons' as pilots have put it.

Positive pitch stability for the Spitfire FM in the sim is also confirmed, as opposed to the real life longitudal pitch instability. This is, again, important for the flying experience: the very low stick force per g and slight instability meant that real Spit had to be handled with careful movements on the stick, and with routine aft-and-fore movements on the stick to prevent the aircraft to tighten up itself. I do not think this was particularly dangerous (though the low stick force per g had some safety risks, admitted by the manual), but it was characteristic of the Spitfire's handling.

+1

how should something that was added to increase reliability increase the risk of overheating which would strongly reduce reliability? For me this is contradictory.

You seem to miss a detail - the temperature of the coolant agent is rather irrelevant, it can be of very high temperature, or even near/at/above boiling point as long as the temperature of the engine components are within permissable temperature limits. The two are not mutually exclusive. Yhe coolant may boil pretty quickly, be at very high temperature, what matters is the interaction between the coolant components and the coolant, of which the coolant's temperature is an indirect indication to the pilot about the engine component's temperature.

So say with a pure glycol coolant 140 degrees celsius may indicate that the engine compontents are about (iirc) 400 celsius, while when using pure water 90 degrees may indicate the very same, since water has a much higher heat transfer capacity (its more effective at carrying away heat).

I suppose they changed the coolant agent type to water-glycol mixture on later Merlins because they realised glycol alone simply cannot transfer heat fast enough, and by adding 70% water this increased greatly. This was usually the practice anyway, an 50-50 or 70/30 mix was generally used by everyone. The DB 601A had used 47% water, 50% glycol and 3% mixture of lubrication oil and water (1:2), which may explain why the DB powered planes do not overheat so easily compared the the all-glycol cooled Spitfire Mark I / Hurricane Mark I.

Coolant circulation may be also of important - the DB 601A circulated coolant for example at 65 000 liter / hour rate.

Glycol permitted higher coolant temperatures without the mix boiling away, and was an anti freeze too for higher altitudes (where temperatures can be easily at the -40 degrees celsius range).

Hurricane ~15 gallons, was tested in a climb with 2600rpm/6.25lb boost, result is that in English summer conditions (25°C at sea level) it can do this without overheating (oil & glycol).

I have already said that in a previous posting when I replied to the Crumps pilots notes

In a high speed dive it is possible to exceed the G limit, if you pull up too quickly.

So I don't see what the problem is. The only problem is the emphasis on it is easy. The pilots notes don't say that its easy, that say that it is very easy for the pilot to impose high load factors when looping, pulling out of dives or doing tight turns. Something any pilot of any airforce would agree. It then goes on to say that it is well within the pilots power to exceed 10G. If the Spitfire goes past 10G then you can expect the wings to come off.
I do not have any problem with the SIM breaking the wings off should the Spit exceed 10G

However its the how easy is it.
It depends on the individual but you would expect most pilots to lose consiousness at 7-8G and tunnel vision happens well before then. The Sim should show a tunnel vision effect at around 4G and a loss of consiousness at around say 8G.

All aircraft will have their break point whereas the effect on the pilot of the G forces is a constant and would apply to all.

In the real world it would be a rare pilot who delberately went past the point of consiousness it would have to be a real emergency, last throw of the dice situation. This would explain why it was rare to have an accident of this type.

The only situation I can see this happening is if the pilot yanked hard on the controls adn suddenly went through the passing out limit. Even here they would probably have a chance to ease off the controls as there are four stages, 1) a loss of colour vision, 2) tunnel vision 3) blacking out whilst stayng consious and then 4) passing out.

So to sum up, if the Pilot decides to go into a state of passing out and then the aircraft goes through its limits, you have a chance of things breaking up.

Blacking out takes time, damaging the airframe does not. There's no reasonable way to exceed the airframes limit in a sustained manoeuvre, however, in a sudden pull out, or due to buffeting with elbows not fixated, it may happen.
Put it as you want, personally I'd not agree with "dangerously low" control forces as propagated by some, nor do I agree that it was a none issue. The Spitfire II pilot notes had the paragraphs added in early 1940, after at least two fatal accidents due to wing failure had occurred and several Spitfires went to maintenance with bend wings. It wasn't a that rare thing to happen, but certainly Spitfires weren't falling from the sky as some here seem to believe. An extra warning was deemed necessary, as pilots transferring to Spitfire equipped units simply were not used to a feature like that. WRT elevator forces, I'd say that the Spitfires elevator forces were not sufficiently high to prevent accidents. Hence they were getting some attention.
Once more about longitudinal stability - the about neutral static stability of the Spitfire gave a lot of pitch reaction to little elevator movement. However, as opposed to what some claim here, the airframe would not self destruct given a bit of elevator input, as would be the case in a statically unstable aircraft. It was not necessary to pull back the stick to get a pitch up, and then push the stick forward to maintain controlled flight. A low static stability means that an aircraft needs a lot of time to settle around a new condition. This in turn means, that if you want a strong initial reaction, you'll have to pull back the stick like you would in a more stable aircraft, however, you'd end up at a lot more g. Or, you can pull back more gently and end up at the same g as a more stable aircraft, but you'd have a slower initial reaction. This leads to the pull - push routine an experience pilot would employ while putting the Spitfire through manoeuvres. Large deflection for a quick initial reaction, eased forward for moderate final loads. This is not critical at all, as the stick forces increase as the g load builds up. In a normally loaded Spitfire I, the pilot would still have to exert near 50 lbs of force to damage the airframe.
On to dynamic stability - short period oscillations were sufficiently damped by the Spitfire. Long period oscillations were not. This was however, typical for aircraft of that era, and opposed to what one poster claims, fighter aircraft of that time in general were no hands off aircraft. In fact, the Spitfire stability in long period oscillation is above average from what I've seen, much better than say a Hurricane. One of NACA's chief test engineers states that all fighter aircraft they tested were dynamically unstable in long period oscillations. They do not matter much to the pilot while flying, where they do matter is if the pilot's unconscious, and regains consciousness only to find himself in a steep spiral dive he can't get out of.
I'd recommend that instead of going over the same Spitfire chart time and again, try finding charts for other aircraft. This would certainly help to get the proper perspective, and maybe even an overall more accurate FM for many planes, not just the Spitfire. The focus of some on that plane is worrying.

The biggest problem with using pure ethylene glycol as a coolant is that it is less effective at conducting heat than water so, as it circulates around the engine, it is less effective at keeping engine components cool. While the high strength alloys and other metals developed by the likes of Rolls-Royce for use in aero engines were able to withstand higher temperatures than earlier metals, components such as gaskets and oil seals were more likely to fail - early Merlin engines were renowned for their oil leaks. Head gasket failure in the middle of combat ops is no fun.

A second problem is that in its pure form Ethylene glycol is flammable, thus it was a hazard to use 100% glycol in combat aircraft. The Merlin II and III series had a normal coolant temperature of 90°, and 120°C emergency maximum - close to the flash point of glycol http://www.npi.gov.au/substances/eth...col/index.html Mixing glycol with water increases the flash point while preserving the anti-freeze, anti-corrosive properties of glycol.

Thus the Merlin XII and XX series (30% Glycol, 70% water) were able to run at higher temperatures 105° normal to 125° for climb, 1 hr maximum and 135° +12 lbs boost 5 minutes while the vulnerable gaskets and oil seals were less prone to failure.

I don't know why the British adopted 100% glycol, although I remember reading about it somewhere.

Excellent summary.

And that is the point where you are wrong, according to the NACA - tests!

No, it's exactly what is stated in the NACA report.

JtD
I wouldn't disagree with your summary, nicely put.

What Theory???

What are you talking about????

:confused:

If it is typical then we should have a huge list of designs.

I can't wait see this long list!

I can only think of three designs that suffered from this issue.

Now how many continued on in service with this issue without it being addressed and fixed?

That is a very short list....

NONE

So, to sum up the latest spin on the Spitfire instability....


It was not a big deal, it enhanced the aircraft's combat capability, and those meddling engineers said,

"Hey we can't have the Spitfire be better at everything, let's pork the stability by adding these inertial elevators!!"

:rolleyes:

Please point this out. I smell a misquote or misunderstanding!

Seriously?

We're back to using a MK V test to change the FM for a MK I/II again are we...?

I've been flying red for a few weeks now, the 8 guns are very addictive! :)

http://i51.photobucket.com/albums/f3...l/fuselage.jpg

http://i51.photobucket.com/albums/f3...826_155011.jpg

All the early mark spitfires, until fixed with inertial elevator systems had the instability at aft and normal CG as tested by the RAE.

The NACA gives us the more detailed measurement and insight into specific behaviors. Unfortunately, the RAE did not have the level of sophistication or equipment at the NACA disposal.

All we can prove is that the RAE said the early marks were unstable at aft and normal CG, we have one measurement of stick forces, stability diagrams for long period oscillation.

We can prove that the basic stability characteristics in the game are not representative of the real aircraft.

Technically, you are right though, we don't have the level of detail provided by the NACA reports from the RAE and none of the NACA material is about the early Mark Spitfires.

Maybe your right and we should not model the stalling characteristics of the Mark V either.

Just go with what the Spitfire Mark I and II Operating Notes say about the sudden, violent, stall that results in immediate spin if not corrected.

No, crumpp,

[irony]dont you know that the famous pre stall warning of the Spitfire made it physically impossible for the pilot to enter a high speed stall, let alone the following spin?
There is no way that a pilot could ignore this mighty shudder and move the steering column another quarter inch to get this violent reaction, even with only a few pound pressure needed.
No sane pilot would do this, so it doesn't have to be modeled.[/irony]

Aww, thanks.. x

You see my point though. Save it for if and when we actually get a MkV.

The temperature 'issue' is more interesting atm.

Got any data on that?

Having gone through the Battle of Britain Then and Now Mk V I can say that 33 Hurricanes and Spitfires were lost or damaged through non-combat related engine failure, while 43 Bf 109s were lost or damaged because of non-combat related engine failure between 10 July and October 31. Given the relative strengths of the aircraft types this would be a fairly even attrition rate.