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Spit IX - max level speed at sea level?


philstyle
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Anyone know what the expected max level speed at sea level is for the spit IX variant we have in DCS?

 

Assuming, +18lb boost, 3000 RPM. Full tank. With guns and ammo. No bombs. Radiator open (on auto it wil full open anyway).

 

 

External sources indicate anything from 330 mph (Spitfire J.L.165 with Merlin 66 at 18Lbs), 336mph (Spitfire F. Mk. IX BS.543 (Merlin 66)).

And LF Mk.IX MA.648 - 340 mph (this variant had injector installed - although it is confirmed as having ful armament on board)

 

http://www.spitfireperformance.com/spitfire-IX.html - and YES, I know some people don't like this website.....

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Yoyo posted last Year Data's about Top Speed and Climb Rate somewhere deep in the first Spit Discoussion Thread. Can not find it currently, but i Remember the Top Speed was the average Performance of 3 or 4 Spitfire taken in to account.

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Yoyo posted last Year Data's about Top Speed and Climb Rate somewhere deep in the first Spit Discoussion Thread. Can not find it currently, but i Remember the Top Speed was the average Performance of 3 or 4 Spitfire taken in to account.

 

Ahh, grand. I will try to find it.

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Ahh, grand. I will try to find it.

 

Found it :D

 

PS: was on my PC left have no description you have to find yoyo's Post for clarification what the DCS Performance is, but there all close to gather somewhere 335 MPH I guess.


Edited by MAD-MM

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Perfect! thanks.

 

Alhough now I'm stuck wondering why I can only get 315mph max-level-speed at 0ft. . . a full 20 to 25 mph off the pace.


Edited by philstyle

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Perfect! thanks.

 

Alhough now I'm stuck wondering why I can only get 415mph max-level-speed at 0ft. . . a full 20 to 25 mph off the pace.

 

I don't get that bit.

 

Max speed is 407 mph @ 22,000'

..

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Why don't you get it?

 

I was asking about the max level speed at sea-level. What the max level speed at ANY other altitude is irrelevant.

 

The data indicates that at sea level I should be able to obtain 335-340mph. I can only obtain 315mph at that altitude. If this is the case, then, as I see it; either (a) I am flying incorrectly, or (b) I am not setting the insutrments up correctly, or © my the TAS/IAS conversion in the black sea is markedly different from British seas, or (d) the modelling is incorrect.

 

Because Phil you write 415 and not 315 Top Speed, Spit with 415 at sea Level would be headache for every Jet Fighter :D

Edit to late

Once you have tasted Flight, you will forever walk the Earth with your Eyes turned Skyward.

 

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The Spits were tested with the rad flaps closed.

 

Ours are open. This will make a big difference.

 

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Perfect! thanks.

 

Alhough now I'm stuck wondering why I can only get 315mph max-level-speed at 0ft. . . a full 20 to 25 mph off the pace.

 

Phil,

 

I got 535 kph (332 mph) sustainable when the Spit was first released. However, I have not bothered to keep making progress with it as the Spit is so very much slower than every other aircraft that there is simply no advantage in it. Instead I have concentrated on best combat cruise speed, combat settings and all the various economy settings. By the book, at the extreme end, -4lbs boost and 1800 rpm burns 30 gallons per hour and -2 @ 2000 rpm burns 40 gallons per hour. I have found the economy settings more useful than top speed at sea level settings, LOL. However, I must confess that I have not actually tested the book economy settings against the DCS model.

 

Happy landings,

 

56RAF_Talisman

56RAF_Talisman

 

Spitfire! 'That's no aircraft, that's a bleedin' angel'

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The Spits were tested with the rad flaps closed.

Ours are open. This will make a big difference.

..

 

It would be nice if we could close the radiator flaps then wouldn't it....

But not all tests specify that the radiators were closed. Some don't provide any indication of rad setting at all


Edited by philstyle

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would be nice if we could close the radiator flaps then wouldn't it....

 

Phil,

 

I believe the manual says that the Spit rads open at 115 deg +

So I assume that the max level speed is achieve within that temp range.

I certainly manage my max speed at sea level within that temp range and the rads don't open.

 

Under 115 deg, I think the rads are set at min drag position (Meredith effect), but I could be wrong about that.

 

So, I think the rads are never actually closed shut tight, but closed to the minimum drag position.

 

Perhaps a real expert can confirm this.

 

Happy landings,

 

56RAF_Talisman

56RAF_Talisman

 

Spitfire! 'That's no aircraft, that's a bleedin' angel'

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I'm getting 335 mph IAS - 3000 rpm, max engine boost (18 lb?), neutral trim, radiator set to auto, altitude 600 ft, fuel 100%, full ammo load. DCS 1.5.6

 

${1}

 

 

Nice one Snapper, but 600 feet is cheating :P

Get down man!

 

Happy landings,

 

56RAF_Talisman

56RAF_Talisman

 

Spitfire! 'That's no aircraft, that's a bleedin' angel'

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I'm getting 335 mph IAS - 3000 rpm, max engine boost (18 lb?), neutral trim, radiator set to auto, altitude 600 ft, fuel 100%, full ammo load. DCS 1.5.6

 

 

Interesting stuff Snapper!

But it seems to me you were levelling off from a -500ft/min dive, and you paused the screenshot, but left the engine sound running. That's an instantaneous reading, not a constant level speed.

 

Here's my attempts - 3 of them in slightly different configurations.. I can only get 315 indicated constant, with 320 for a few seconds when I go into a slight descent now and then.... am I doing something wrong.. seems to be trimmed and set up correctly.... maybe my weather conditions/ air temp made the difference?

If I had set my altimeter to 0 would the ASI reading have increased??

 

 

${1}

 

 

FYI: a second video indicates that 330 is possible, however lower rpm is needed in order to get past 315 mph, with radiator set to auto.


Edited by philstyle
commenting on further development later on in thread

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I'm rendering the full almost 6 min video and will post it here. I only showed the last 43 seconds and did a screengrab of the airspeed indicator and magnified it for easier verification.

 

Phil, I have no reason to BS. It is what it is.

 

EDIT: Here is the full video from which I took my first video. The first minute or so is level flight at reduced engine settings, then I increase to 3000 rpms/18 lbs boost. I'm aware of the up and down porpoising, but even on the upward stroke the speed does not decrease below 330 mph IAS.

 

 

I did another run just now testing the radiator at auto, then open. Whenever I opened the radiator the speed would slowly drop below 320 mph (and radiator temp rapidly drop), when selecting auto the speed would gradually increase above 330 mph IAS and rad temp would rise to 110 and hold.

 

I tried adjusting elevator trim to 1 degree up per your video, but that made no appreciable difference in IAS that I could detect.

 

 

Interesting stuff Snapper!

But it seems to me you were levelling off from a -500ft/min dive, and you paused the screenshot, but left the engine sound running. That's an instantaneous reading, not a constant level speed.

 

Here's my attempts - 3 of them in slightly different configurations.. I can only get 315 indicated constant, with 320 for a few seconds when I go into a slight descent now and then.... am I doing something wrong.. seems to be trimmed and set up correctly.... maybe my weather conditions/ air temp made the difference?

If I had set my altimeter to 0 would the ASI reading have increased??

 

 


Edited by ATAG_Snapper
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Well, there's the answer it seems. Phil flew with radiators manual - full open, which caused additional drag and 10-15 mph penalty, Snapper and Talisman flew with them on auto (no, at high speeds auto does not equal full open), drag is lower, top speed a bit higher.

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Well, there's the answer it seems. Phil flew with radiators manual - full open, which caused additional drag and 10-15 mph penalty, Snapper and Talisman flew with them on auto (no, at high speeds auto does not equal full open), drag is lower, top speed a bit higher.

 

No. I did three tests. Both settings "open" and "auto" were conducted separately, and are shown in the video, but the speed obtained was the same (315mph), provided 3,000rpm was used.

 

There is a way to get 330mph though. . . I've just worked it out. . . I think...

You have to use auto-rad, AND use less than 3,000rpm at least until your speed is above about 320. With the lower rpm, the engine temp will be lower, thus closing the radiator even further. This will reduce drag and increase airspeed.

 

If you accelerate up to 300 with 3000 rpm in level flight, you can't get past 315, irrespective of radiator setting. Seems that using the the 3000rpm (during acceleration) will result in enough heat to force it open enough to create the necessary drag to keep the speed below 320.

However, if you use lower rpm, you can get past 320 and then on to 330 even. Same goes if you get up to 320 in a dive, then you can hold 330....

 

Next video coming up soon.

 

This seems to demonstrate the above thinking:


Edited by philstyle

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Hey Phil! Glad to see the SoW team in DCS now. Usually these charts are with ram effect taken into consideration. Try diving into it and see what you can actually sustain. Good effort btw!

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No. I did three tests. Both settings "open" and "auto" were conducted separately, and are shown in the video, but the speed obtained was the same (315mph), provided 3,000rpm was used.

 

There is a way to get 330mph though. . . I've just worked it out. . . I think...

You have to use auto-rad, AND use less than 3,000rpm at least until your speed is above about 320. With the lower rpm, the engine temp will be lower, thus closing the radiator even further. This will reduce drag and increase airspeed.

 

If you accelerate up to 300 with 3000 rpm in level flight, you can't get past 315, irrespective of radiator setting. Seems that using the the 3000rpm (during acceleration) will result in enough heat to force it open enough to create the necessary drag to keep the speed below 320.

However, if you use lower rpm, you can get past 320 and then on to 330 even. Same goes if you get up to 320 in a dive, then you can hold 330....

 

Next video coming up soon.

 

This seems to demonstrate the above thinking:

 

Hi Phil,

 

I find that 2750 rpm is always the best setting for this test. My test today with full 18lbs boost and 2750 rpm gives me a sustained (15 mins +) speed of 531 kph (330 mph) at wave tops (prop almost in the water all the way, lol). Carb Air Intake lever fully back, rads auto and trim, trim, trim. Just leave at full boost and 2750 rpm and let the speed build up gives me 531 kph with no bother at all. I use the in-game speed bar for testing as I presume it is more accurate than me reading the cockpit gauge. I find I don't need a power dive to achieve 531 kph. Even using a power dive the speed bleeds off back to 531 kph as the sustainable speed eventually. The speed bar regularly flicks up to 532 kph, but I take 531 kph as my ultimate measure because that is the most sustainable speed I can make without dropping any lower over a long period of time.

 

P.S. I don't use 3000 rpm for this test at all, as it gives a lower speed than 2750 rpm. In combat, I only use 3000 rpm for a very short period of time (seconds) when needed in a climb in a combat situation (tactical egg for example), and lower rpm back down when nose down or level.

 

Happy landings,

 

56RAF_Talisman


Edited by 56RAF_Talisman
spelling

56RAF_Talisman

 

Spitfire! 'That's no aircraft, that's a bleedin' angel'

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Carb Air Intake lever fully back, rads auto and trim, trim, trim

 

 

Interesting that you have the carb intake fully back.

I can get 330 mph with it full forward, do you see an air-speed gain in having it back?

On YouTube: https://www.youtube.com/philstylenz

Storm of War WW2 server website: https://stormofwar.net/

 

 

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Hey Phil! Glad to see the SoW team in DCS now. Usually these charts are with ram effect taken into consideration. Try diving into it and see what you can actually sustain. Good effort btw!

 

Hi mate, yeah SoW is looking very seriously at DCS now... we're all playing DCS regularly and exploring what options there might be for an SoW-style campain/ server.

On YouTube: https://www.youtube.com/philstylenz

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