109 E4 max level speed on the deck

[philstyle]

I've never been able to find max level speeds for the 109s in the TF WIKI, despite them being provided for the RAF fighters.

Can someone tell me what the max level speed for the E4 is on the deck?

I'm finding that the sustained level speed I can attain after a dive is greater than the level speed I can get to after accelerating, even with exactly the same engine settings.. This seems odd...

[Gromit]

same map and direction Phil?

Wondering if wind is playing a part?

[philstyle]

same map and direction Phil?
Wondering if wind is playing a part?

Blank map (ie just the standard summer channel map). Self hosted (but online)
Zero wind. Midday. Zero clouds.
Heading north and south, same result.
5 miles off french coast.

[hnbdgr]

I think it was 485km/h on the E4 without WEP.

I'll do some test tonight to confirm. There's 4 different possible speed results for the 109

E1 - 601A (old supercharger)
E3/E4 - 601A (new supercharger)
E3b/E4b - 601Aa
E4/N - 601A/N

I will test this tonight again

[ATAG_((dB))]

same map and direction Phil?

Wondering if wind is playing a part?

Technically it doesn't matter since your only source of airspeed will be your indicated airspeed. Wind will only change your ground speed and we have no way to measure that in CloD.

[philstyle]

I can get 483 sustained without a dive beforehand.
After coming out of a dive, I can get 488, so long as I don't let it slow down below that (bad trim or by climbing again). Once I slow down below about 485 I am unable to get it back above 485 again....

All my testing so far is without any WEP.

I don't understand why I cannot sustain the same speed without a dive beforehand as I can with a dive before hand. Although it is only 5kph... (1%)...

[ATAG_((dB))]

Not sure if it's been modeled but in a sort answer I will say momentum.

[philstyle]

Not sure if it's been modeled but in a sort answer I will say momentum.

I thought that at first too.. but if "momentum" is the reason... it defies physics I think.... I can understand that more momentum means it just takes longer for it to slow down to max level speed... but for it to perpetuate is not possible.
Also, wouldn't it apply to the other aircraft too...? I can't get this effect from other types.

It must be something to do with my handling.. I will keep trying.

[ATAG_((dB))]

Yes t should apply to others too. There is so much involve to squeeze the last once of E, ie the trim, the mass, then entry speed, the level off, the technique employed. I will take the wiki data lightly since it was done at the beginning of aviation testing and that they didn't have the standard set's as we have today, test result could differed from pilots to pilots . In today's test flight it's done with computer calculation and confirm by averaging flight test result done by skill test pilot that follow the same procedure over and over again.

[RAF74_Buzzsaw]

There is a RAM air effect modeled in the game.

Basically that means when an aircraft is travelling at a higher speed, it is having air forced into its supercharger inlet system at a higher pressure than when it is travelling at lower speeds.

That means there is a minor gain in hp... so if the aircraft is in a dive at 600 kmh it is generating more hp than if it is in level flight at 400 kmh.

This explains why you can sustain more speed when you start off in a dive, ie. at a higher speed ie. generating more hp through the RAM effect... the gain is limited so the speed advantage is only a few kmh.

I am not going to comment on level speeds or how we arrived at them.

[SoW Reddog]

There is a RAM air effect modeled in the game.

Basically that means when an aircraft is travelling at a higher speed, it is having air forced into its supercharger inlet system at a higher pressure than when it is travelling at lower speeds.

That means there is a minor gain in hp... so if the aircraft is in a dive at 600 kmh it is generating more hp than if it is in level flight at 400 kmh.

This explains why you can sustain more speed when you start off in a dive, ie. at a higher speed ie. generating more hp through the RAM effect... the gain is limited so the speed advantage is only a few kmh.

I am not going to comment on level speeds or how we arrived at them.

How long does the effect last?

[ATAG_Dave]

How long does the effect last?

logically indefinite i think..... (having dived) u have the extra speed, so u have the extra hp so u maintain the extra speed (relative to the situation where u are having to accelerate to vmax where u dont have the extra speed in the first place to gain you the extra hp).....

[hnbdgr]

I just measured the top speed on an E-4 with 100% fuel in the "free flight - channel" mission. I flew + measured in 3 different directions with and without wep.

Top speed without WEP - 486-487 km/h
Top speed with WEP touches 499-500 seconds before WEP clock resets.

This was without a dive, starting at about 430kmh as close to the water as possible. (20 feet, +- 5)

EDIT: Tested on AX dogfight server, same results. got 487/500

Water Rad: Closed for 1+1/4 revolutions
Oil Rad: 32%
RPM management: automatic

Speed and height readouts were from TF devicelink interface.

[SoW Reddog]

logically indefinite i think..... (having dived) u have the extra speed, so u have the extra hp so u maintain the extra speed (relative to the situation where u are having to accelerate to vmax where u dont have the extra speed in the first place to gain you the extra hp).....

But Buzzsaw's example has the higher speed required to get the effect at 600 kmh, not the "few kmh" the gain equals. Surely it is logical therefore to expect that there is a drop off.

[philstyle]

But Buzzsaw's example has the higher speed required to get the effect at 600 kmh, not the "few kmh" the gain equals. Surely it is logical therefore to expect that there is a drop off.

Agreed. If it is indefinite, it is "something for nothing". Perpetual motion machine anyone?
One would also then expect it to be effective for all types (all types with rearward emitting exhaust)....

[RAF74_Buzzsaw]

Agreed. If it is indefinite, it is "something for nothing". Perpetual motion machine anyone?
One would also then expect it to be effective for all types (all types with rearward emitting exhaust)....

Wrong. No perpetual motion machine... because drag increases exponentially whereas hp increase due to the RAM effect does not.

And I am not talking about the effect of "rearward emitting exhaust" thrust... which is does generate thrust, (that's another factor) but in this case I am talking about the pressure generated by forced induction of air into the supercharger inlet... due to speed at which the aircraft is travelling. In effect the increased air pressure in the inlet at higher speeds increases the efficiency of the supercharger and allows it to force a larger quantity of air/fuel into the combustion chamber... hence more hp.

But we are talking very small increases.

If you look at the engine power charts for the various national types, German and British most noticeably, you will see that often the charts include a theoretical RAM effect line at a given speed. This is also why the FULL THROTTLE HEIGHT, ie. the height at which maximum horsepower is able to be generated is different when an aircraft is in a low speed climb as compared to when it is in level high speed flight.

End of my comments re. this thread.

[philstyle]

Wrong. No perpetual motion machine... because drag increases exponentially whereas hp increase due to the RAM effect does not.

So, at, say 600kph the engine gets some extra HP due to this ram air pressure.
Then, when you slow down to ~500 kph the engine still has some more HP (even though the ram air pressure is now reduced). . . and it keeps this HP indefinitely, allowing you to maintain raised airspeed thus giving you more ram-air and thus more HP, which allows you to go faster, thus producing more ram-air and HP... ad.infinitum?

The question here is not the effect of Ram air on HP (no-one needs this explained as far as I know), but the duration of the effect.
This is the qeustion Reddog also asked. For how long does the HP gained last, does the loss of airspeed result in a reinforcing-cycle (resulting in subsequent ram-air loss and airspeed loss) which will inevitably terminate at the aircraft's normal best level speed, or will this ram-effect somehow perpatuate in a positive-reinforcing cycle, resulting in a never-ceasing raised HP and airspeed.

[philstyle]

Just saw Buzzsaws last line.
thanks for the explanations. Salute.

[ATAG_Dave]

The question here is not the effect of Ram air on HP (no-one needs this explained as far as I know), but the duration of the effect.
This is the qeustion Reddog also asked. For how long does the HP gained last, does the loss of airspeed result in a reinforcing-cycle (resulting in subsequent ram-air loss and airspeed loss) which will inevitably terminate at the aircraft's normal best level speed, or will this ram-effect somehow perpatuate in a positive-reinforcing cycle, resulting in a never-ceasing raised HP and airspeed.

Simplified example using made up numbers assuming all other factors (wind, altitude and so on) being equal:
1. A plane accelerating to vmax at 100ft of (say) 500kph. At that vmax he has (say) 1000hp

2. Same plane dives to 100ft from 5000ft and reaches 600kph gradually slowing to (say) 505kph in level flight. At 505kph he has (say) 1050hp (extra 50 due to RAM effect).

As all other factors are equal (drag, wind, altitude etc) plane 2 simply has more hp, so it can achieve and maintain a higher vmax than plane 1.

IN this example plane 1 & 2 have the same drag, but plane 2 has more power and so can pull itself through the air faster than plane 1. As it continues to pull itself through the air faster than plane 1 it continues to have more power and so....(rinse and repeat)

So RAM effect is not 'free' - you buy it by gaining then losing altitude but once you have it you continue to have it and so you will always have more power (& hence a higher vmax) than a plane who never had it....

[SoW Reddog]

Dave. If the required speed increase to generate the extra HP requires a dive, the HP could not remain permanently afterwards in level flight. There might be a prolonged period of residual speed but at some point all things being equal the aircraft must slow down. All I want to know is how long that period is.

[philstyle]

If the required speed increase to generate the extra HP requires a dive, the HP could not remain permanently afterwards in level flight.

I can't quite get my head around this.. but Dave might be right.
If the additional thrust generated from the additional airspeed is enough to overcome (or at least equal) the additional drag caused by that extra airspeed then I suppose it could go on in steady level flight at the higher speed. But, as soon as the extra thrust produced is less than the aircraft's drag at that airspeed, the aicraft will decelerate to the normal Vmax as the engine returns to its normal thrust generation.

This starts getting pretty damned complex. The greater airspeed from the additional thrust means more lift (more air passing over the lift-generating surfaces). So the faster machine has more lift, and needs to have some of that lift removed by pionting the nose down a little, otherwise it will climb. Doing this will change the angle of the air relative to the radiator. Will that reduce the ram-air pressure thus reducing the HP availabe? Possibly...

I still can't work out if we end up in some kind of reinforcing loop here, or if everything euqalises out back at the normal Vmax!

[ATAG_Dave]

Dave. If the required speed increase to generate the extra HP requires a dive, the HP could not remain permanently afterwards in level flight. There might be a prolonged period of residual speed but at some point all things being equal the aircraft must slow down. All I want to know is how long that period is.

The dive provides an initial air speed greater than normal vmax. In subsequent level flight this speed will then drop of course as gravity is no longer assisting. But because you have a residual speed greater than 'normal' vmax you have more RAM effect than at normal vmax so you have more power than can be achieved by accelerating to 'normal' vmax so you can maintain a (slightly) higher than 'normal' vmax. All other things being equal you will always maintain a slightly higer vmax than if you accelerated to it 'normally' - the fact you have more speed means you have more power...

I agree it all sounds unlikely but thats how it works (bikes, cars, planes - its all essentially the same, tho the former would require a hill rather than a dive of course).

[philstyle]

All other things being equal you will always maintain a slightly higer vmax than if you accelerated to it 'normally' - the fact you have more speed means you have more power...

If so, is this the same for all aircraft in CloD?
The spitfire seems happy to drop back to normal Vmax after about 1 minute..... is that because a supercharger necessary for this ram effect?

[ATAG_Dave]

If so, is this the same for all aircraft in CloD?
The spitfire seems happy to drop back to normal Vmax after about 1 minute..... is that because a supercharger necessary for this ram effect?

Absolutely no idea . I was just trying to explain how the (very counter-intuitive) RAM air theory works - I have no idea how all this plays out in clod

[philstyle]

Absolutely no idea . I was just trying to explain how the (very counter-intuitive) RAM air theory works - I have no idea how all this plays out in clod

Very interesting discussion nonetheless. I've ended up spending half the day reading up on piston-engine mechanics as a result!

[philstyle]

To summarize where I think I have got to.

I same that the air coming into the engine at the higher speed is of denser volume (partially compressed) and therfore more air squeezes into the cylinder during the period that the inlet valve is open.
Because there is more O2 in the chamber, the spark will generate more explosive power, that is when the engine gets more air, it is more powerful.
Now, the only way to get this extra air is to go faster. So the going faster has to occur BEFORE the combustion. The only way to get this extra HP, is therefore to make the aircraft go faster. And the only way to do this (if you are already at Vmax) is to dive.
So, the Ram-air thing makes sense, and why you need to dive and exceed Vmax to get the extra power also makes sense. Because it is the extra O2 that gives you the better combustion (and power).

However, my next issue is:
How does that power get converted to thrust?
If we are excluing the rear-ward exhaust thrust... the only way to generate more thurst from a prop engine is to either spin the prop faster OR to coarsen the prop pitch (an maintain RPM).

If the above is true (which I think it is!) then there should either be:
1. An increase in RPM , OR
2. A change in prop pitch.

But I don't recall seeing any of these things happening. The prop-pitch control and meter does not move. Also, the RPM doesn't change as far as I recall. Must remember to look at this tonight.
If the prop pitch or RPM change at all in the process of dropping from 500 (steady) down to normal Vmax, then that would be grand.
So how is the extra engine power being converted to thrust?
I also still aren't sure what effect the necessary angle-of-attack adjustemtn would make to the ram-air effect. Obviuosly in a car it does not matter. Cars do not need to maintain level flight, they just go faster. But an aircraft wil climb if thurst increases, thus requiring a change in AoA whihc would then alter the angle of air comgin into the intake and possibly reduce the O2 available in the chamber...

[Vlerkies]

Phil, The concept of greater sustained HP seems to have settled, pressure and density (SC related). Its the 'bleed to normal flight' point that seems to be the issue,is that correct?

You are really questioning the duration of said speed (+5kph)?

[JG27-Gaidin]

Salute All,

I think I get what they are saying, let's see.

Once you initiate a dive, your forcing air into the intake to produce the "Ram Effect". As you level out and your speed drops you will still maintain a level of forced air into the system. There is just enough air forced into it to maintain the extra horsepower until you drop your speed below the point of the "Ram Effect". I would assume any change in flight, other than level flight, would change the amount of air being introduced into the system. Different AOA would lower the airspeed and change the amount of air being forced into the system lowering the horsepower gained by the "Ram Effect".

How'd I do?

Gaidin

[philstyle]

You are really questioning the duration of said speed (+5kph)?

Yes of course I am questioning it. Why not, are you not interested? Don't you ask questions about things you are interested in?
Questions are good things. Ask them.

I'm not promoting any changes be made... I'm just interested to know how detailed this sim is. I would be mighty surprised if any flight models go near this level of detailing - perhaps with the exception of DCS, but even then that was built for Jets, so I don't know how their piston-engine modelling works.

[Vlerkies]

Yes of course I am questioning it. Why not, are you not interested? Don't you ask questions about things you are interested in?
Questions are good things. Ask them.

Strewth a simple confirmation would have sufficed.
I was just asking to make sure I understood what you were asking, that's all, bloody hell.
After post #26 I wasn't quite sure.

Anyway, I can see where this is heading, count me well out.