Throttle and propeller RPM!

[escaner]

In game a key/button for simulate this "override/stop"?

 

Override/stop OFF: throttle control PP.

 

Override/stop ON: propeller pitch control became effective (by axis, keys, buttons/HAT).

 

From the text in the image you posted, it looks the prop lever still sets rpm (it says it can be used as previously), but the throttle will override it when that setting is too low for the boost. So it is not an ON/OFF, but an axis.

[Krupi]

The only difference between the XIV and previous Marks is the range of throttle movement, it was increased on the XIV to give the pilot more control over the griffon engine.

[Sokol1_br]

Originally Posted by Sokol1_br View Post

In game a key/button for simulate this "override/stop"?

Override/stop OFF: throttle control PP.

Override/stop ON: propeller pitch control became effective (by axis, keys, buttons/HAT).

 

From the text in the image you posted, it looks the prop lever still sets rpm (it says it can be used as previously), but the throttle will override it when that setting is too low for the boost. So it is not an ON/OFF, but an axis.

 

The ON/OFF command I suggest is only a game command (key/button) to simulate that you are moving the lever over the stop on quadrant to override the throttle control over prop pitch, as said in PN, since this is a physical movement that can not replicated with our joysticks - who not even has proper lever for prop pitch control (VKB you are hearing? :) ).

 

For example, Spit Mk.II in CloD has that red lever at end of course who prevent use BOOST, by press a key/button you move the lever and can move the throttle a bit more for engage BOOST, in practice you joystick throttle course is expanded to "110%". The game allow set a position for 100% before the end of joystick throttle course, so one that have a throttle with detent (Cougar/Warthog) can program this "button" in this point of course to move the lever, without need to press a key/button.

 

But the key/button option is necessary for "Casual Joe Pilot" with his "3in1"

joystick and slider for throttle control. :joystick: Edited November 14, 2016 by Sokol1_br

[Cripple]

The only difference between the XIV and previous Marks is the range of throttle movement, it was increased on the XIV to give the pilot more control over the griffon engine.

 

Doesn't the mk XIV have an entirely different style of throttle quadrant? Black, with rails and the different style of knob on the airscrew control - now named "propeller"?

 

Scroll down this link to see the difference between the marks. None of their replicas have the contentious "stop" though! :megalol:

 

http://spitfirespares.co.uk/Pages/controls.html

[Sokol1_br]

Scroll down this link to see the difference between the marks. None of their replicas have the contentious "stop" though!

 

Mk.XIV quadrant replica in Spitfirespares:

 

image uploading site

 

http://spitfirespares.co.uk/Website%20products%20474/Spitfire%20throttle%201%20l;arge.jpg

 

https://www.haraldjoergens.com/panoramas/spitfire-td314/files/

Edited November 15, 2016 by Sokol1_br

[Cripple]

Ha, Ha! :lol: Well spotted!

 

I was looking more at the IX and previous. The mk XIV throttle is for a different engine, and largely irrelevant (as we are in a Mk IX sub-forum). You'll note it is very different to the earlier models though.

 

Here are some of the pics I have of the IX throttle with the later stop...

[Sokol1_br]

Anyone has this drawing in better resolution?

 

Don't know for what "Mk" is, looks like it has the "stop" (red arrows).

 

 

Maybe show the mysterious "interconnection device". :)

Edited November 16, 2016 by Sokol1_br

[Friedrich-4B]

Ha, Ha! :lol: Well spotted!

 

I was looking more at the IX and previous. The mk XIV throttle is for a different engine, and largely irrelevant (as we are in a Mk IX sub-forum). You'll note it is very different to the earlier models though.

 

Here are some of the pics I have of the IX throttle with the later stop...

 

Interesting; the throttle lever seems to have the twist grip that was used to adjust the recticle on a gyroscopic gunsight.

 

From

 

Here are some comments on adjusting the Merlin for long-range cruising.

 

[Cripple]

Anyone has this drawing in better resolution?

 

Don't know for what "Mk" is, looks like it has the "stop" (red arrows).

 

 

Maybe show the mysterious "interconnection device". :)

 

Yup, I do...:) That's an early mk IX throttle quadrant. The metal bit you've highlighted seems to be merely to hold the lever in an aft position - and doesn't seem to penetrate through to the throttle lever itself. It is also replaced by something else (the other style of stop?).

[Alicatt]

Interesting; the throttle lever seems to have the twist grip that was used to adjust the recticle on a gyroscopic gunsight.

 

 

 

Here are some comments on adjusting the Merlin for long-range cruising.

 

In the video that was posted in this thread https://forums.eagle.ru/showthread.php?t=175971 the pilot is talking about taking his PR Spitfire to Berlin and back, ok it had no armament and extra tanks fitted where the guns were but it is still quite an achievement for what was really a point defence interceptor and not a long range escort fighter.

[Sokol1_br]

Yup, I do...:) That's an early mk IX throttle quadrant. The metal bit you've highlighted seems to be merely to hold the lever in an aft position - and doesn't seem to penetrate through to the throttle lever itself. It is also replaced by something else (the other style of stop?).

 

Thanks for post.

 

At least the part # 61 is labeled "airscrew control stop"... :)

 

But that quadrant is subject to several "MOD".

 

Well a "mystery" lost in time. :D

[Sokol1_br]

Mk.IXe (Historic Foundation) - this picture make the piece 32939 in drawing make sense. :)

 

[NeilWillis]

In the video that was posted in this thread https://forums.eagle.ru/showthread.php?t=175971 the pilot is talking about taking his PR Spitfire to Berlin and back, ok it had no armament and extra tanks fitted where the guns were but it is still quite an achievement for what was really a point defence interceptor and not a long range escort fighter.

 

The lack of guns meant they could fit more fuel tanks in the PR version. The video mentioned tanks in the leading edge of the wings I recall.

 

I am sure too that after firing the guns, the interceptor variants would have a reduction in range. Once the canvas patches were shot away, there must have been considerably more parasitic drag.

[Ala13_ManOWar]

I am sure too that after firing the guns, the interceptor variants would have a reduction in range. Once the canvas patches were shot away, there must have been considerably more parasitic drag.

Some lift can be lost after firing since gun holes breaks the leading edge, I guess it should be like ice pellets sticking to your leading edge in freezing conditions, but "considerably" more parasitic drag? I hardly think so, a bit may be.

 

 

S!

[NeilWillis]

It depends on what you interpret "considerably" to mean. Assuming it may just lead to another 2% extra fuel consumption, if you are operating at the edge of the possible range of an aircraft, that 2% could mean the difference between a beer in the mess, or a dip in the English channel.

 

Loss of lift = increased angle of attack = more drag.

 

It was sufficient extra drag to warrant the holes being patched before flight, so I'd naturally assume it was significant, or why else would they patch them in the first place?

[Alicatt]

Some lift can be lost after firing since gun holes breaks the leading edge, I guess it should be like ice pellets sticking to your leading edge in freezing conditions, but "considerably" more parasitic drag? I hardly think so, a bit may be.

 

 

S!

I used to fly a little Cessna 152, it had a bird strike on the port wing about 2/3rds of the way along it on the leading edge, I flew the aircraft like that and you could really feel the difference from before the bird strike.

 

After the wing was repaired you could see a barely perceptible ripple if the light was in the right direction, to run your hand over it you would not feel it. Still, after that the flying characteristics of the aircraft were different than before the bird strike happened, in the stall that wing would drop well before the starboard one and it took full right rudder to keep her level, if not she would snap into a spin.

 

So from an aircraft that is known for it's docile handling acting like that, with a performance machine like a Spitfire I would think it would make a noticeable difference to her flying characteristics in some way.

[Cripple]

.... or why else would they patch them in the first place?

 

I thought it was reduce the problems with guns freezing/jamming.

[Ala13_ManOWar]

I thought it was reduce the problems with guns freezing/jamming.

Yes, there are some different explains on the canvas patches but I also thought it was related to guns freezing.

 

 

I used to fly a little Cessna 152, it had a bird strike on the port wing about 2/3rds of the way along it on the leading edge, I flew the aircraft like that and you could really feel the difference from before the bird strike.

 

After the wing was repaired you could see a barely perceptible ripple if the light was in the right direction, to run your hand over it you would not feel it. Still, after that the flying characteristics of the aircraft were different than before the bird strike happened, in the stall that wing would drop well before the starboard one and it took full right rudder to keep her level, if not she would snap into a spin.

 

So from an aircraft that is known for it's docile handling acting like that, with a performance machine like a Spitfire I would think it would make a noticeable difference to her flying characteristics in some way.

I know what you mean. I got my licence in a C152, she had a twin in the aero club, but the one I flew was always the best one, the one flying really better, and you could easily tell the difference, two aircraft being the very same exact model and in same maintenance conditions (even same paint job). Obviously those differences comes from tiny details we don't even notice, and yes they influence the flight. I'm sure those gun holes in the leading edge has an influence, but they were the same in both wings so whatever it was it affected the same both wings. I don't think it was so dramatic, specially bearing in mind some warbirds today fly without canvas and miraculously nothing happens, not to mention canvas doesn't follow leading edge 100% to match wing profile at all, on the contrary usually canvas is hollowed towards the gun hole and is somewhat flexible. Have those holes some influence in aerodynamics? Sure, even a bird excrement on your leading edge has, but was that influence so dramatic over the flight nor wasn't engineers aware of that when they designed the Spitfire so they could get rid of it provided it was a so great handicap in combat? I don't think so.

 

 

S!

Edited December 7, 2016 by Ala13_ManOWar

[Davee]

It depends on what you interpret "considerably" to mean. Assuming it may just lead to another 2% extra fuel consumption, if you are operating at the edge of the possible range of an aircraft, that 2% could mean the difference between a beer in the mess, or a dip in the English channel.

 

Loss of lift = increased angle of attack = more drag.

 

It was sufficient extra drag to warrant the holes being patched before flight, so I'd naturally assume it was significant, or why else would they patch them in the first place?

 

The patch was primarily to prevent icing up of the muzzle before firing.

[Nerd1000]

The patch was primarily to prevent icing up of the muzzle before firing.

It also kept dirt out of the gun's workings.

[Kurfürst]

It depends on what you interpret "considerably" to mean. Assuming it may just lead to another 2% extra fuel consumption, if you are operating at the edge of the possible range of an aircraft, that 2% could mean the difference between a beer in the mess, or a dip in the English channel.

 

Loss of lift = increased angle of attack = more drag.

 

It was sufficient extra drag to warrant the holes being patched before flight, so I'd naturally assume it was significant, or why else would they patch them in the first place?

 

Indeed. AFAIK gun ports over the wing do decrease Cl under dynamic conditions, so they do effect overall drag, through loss of lift, which is the more pronounced effect.

 

I wonder if this will be modelled in the FM - i.e. CL change before/after the guns are fired...?

 

And those gun ports weren't exactly small either, rifle caliber MGs barrels are fairly thin themselves, but I suppose the designers had to allow for some air to flow through to allow for cooling of barrel and the gun.

 

[bongodriver]

If the gun port is properly designed then the effect is absolutely minimal, open gun ports such as on the spitfire produce less effect than faired types such as the P-51, you probably get more drag and Cl reduction from the cannons on the Spit than from the gun ports.

 

The primary reason for the fabric patches was to prevent the ingress of debris on take off and ice at altitude, once the guns are fired it's not like the patches disappear but rather end up a bit tatty, either way the effect should be unnoticeable from the pilots perspective but maybe as mentioned by someone else you would burn a few cup fulls extra of fuel.

There certainly doesn't seem to be any hard data on the Spitfire gun ports and historically it has never sounded like a problem so we should leave it to the devs and their discretion.

 

Some research on the issue. (for me the .PDF didn't open in browser but was able to download and view)

 

https://ntrs.nasa.gov/search.jsp?R=19930093506

[Kurfürst]

Yes, that's the report I had in mind, thank you for linking it. Notice that the P-51B gun ports are rather close in their design - obviously the primary consideration was maintenance.

 

The outer MGs on the Spitfire were kind of an afterthought, weren't they, after the requirement for +4 additional MGs arose, they had to enlarge the wing to its well known form, and fit those extra MGs in it whereever possible. Hence their seemingly random arrangement.

 

See the attached picture from the report you linked, for the P-51B installation. On page 17 of this report there is a table, noting DeltaCLmax = -0.05 for the "fabric torn" condition (and -0.12 for the completely unsealed gunport).

 

The curve marked with "+" ("tape torn" rather than completely "unsealed") appear to be most relevant for the change in Drag Coefficient and Lift Coefficient.

 

To me it appears that the drag increase is proportional to Angle of Attack change (i.e. both negative and positive Cl change increase drag with the 'torn' and 'unsealed' installations)

 

Analoges for the cannon installation are also available in the report for Drag increase with Cl increase.

 

My question to the developers is the following: is this Cd / Cl effect from the tape being torn on the gun ports is being simulated in DCS - i.e. for the P-51D and upcoming Spitfire IX LF? Does the FM differentiate between sealed and 'fired' gun ports?

Edited December 7, 2016 by Kurfürst

[bongodriver]

open a new thread and ask is the best way forward I guess, this one is beginning to derail.

[Ala13_ManOWar]

As Bongodriver says, it's starting to be too much off topic, but,

 

My question to the developers is the following: is this Cd / Cl effect from the tape being torn on the gun ports is being simulated in DCS - i.e. for the P-51D and upcoming Spitfire IX LF? Does the FM differentiate between sealed and 'fired' gun ports?

Knowing Yo-yo he probably considered everything that deserves to be considered. Anyway, the attention to those small, tiny, minuscule details starts to be ridiculous. It's not like those has no effect on FM, but, even though they are there, will you even be able to notice them? Will them make such a huge difference?

 

 

S!