Expected Mossie performance vs current plane set

[Drakeshoot]

Hi All,

 

I Pre-ordered as a Pavlovian response and am now working out what I’ve gotten myself in for. 
 

I understand (from wiki) the FB.VI we are getting is a post-June 1942 mark. Probably, and this is pure speculation, the rapidly modified version with Merlin 25’s and a top speed of 385mph. 
 

Wiki tells me that in January of 1945 FBVI’s went toe to toe with Fw190’s (no mark given) and killed 5 for 5 losses which is encouraging but hardly a complete AAR. 
 

Would I be right in saying that DCS’ Axis plane set is mostly late war, mid-‘44ish? if so, will the Mossie be viable in it’s FB role and, more importantly, how should it be fought? As an energy fighter, boom & zooming or a turn fighter with those lovely merlins dragging it round the corner, or do we leg-it and come back with a load of mates with sticks? 
 

I’ve read lots about the mossie’s early-war speed, how does that compare to our late-war souped up 190 & 109?

 

I’ve heard an interesting urban myth about the Mossie and would love to hear from people more knowledgeable, that there was a significant gap (20-40kts) between takeoff speed and controllable single engine speed, so that the loss of an engine shortly after rotation would result in the surviving Merlin producing more torque than the controls had authority to counteract resulting in uncontrollable roll, likely inversion and almost certain death. 

 

 

[Krupi]

At risk of bursting your bubble I wouldn't expect to find the Mossie being used as a fighter outside of highly situational occasions... forced to fight back or catching an aircraft unaware on take off etc... The Mossie is more of a fast strike bomber than a fighter.

Edited August 14, 2021 by Krupi
Terrible English, I was apparently half asleep

[Krupi]

3 hours ago, Drakeshoot said:

how should it be fought? As an energy fighter, boom & zooming 

 

Nothing will really suit the Mossie, it probably won't be anywhere close to the manoeuvrability of any of the current aircraft. 

 

In terms of boom and zoom I don't expect it to hold up either, the engine being only single stage means that performance drops off after a certain altitude so you really don't want to be found at altitude. 

Edited August 14, 2021 by Krupi

[Drakeshoot]

Not burst at all, it’s all grist for the mill. Know what it’s best altitude is given the single stage?

 

 

[Bozon]

50 minutes ago, Drakeshoot said:

Not burst at all, it’s all grist for the mill. Know what it’s best altitude is given the single stage?

 

 

Low gear peak speed is at 12-13k altitude, high gear peak is at 23k.

However, you don't want to be above 12k anyway. Merlin 25s are heavily optimized for very low altitude. In relative performance terms, the lower you are, the better you are relative to other fighters, so that 385 mph at 23k is a completely irrelevant number - your playground will be at 5k or less. Deck speed should be slightly above 350 mph on WEP (+18 boost), which was amazing in 1943, but in DCS we will face 1945 Luftwaffe birds - both the 190D9 and 109K are faster at all altitudes, less so on the deck but the gap gets really big if you try to go much above 10k alt. 190A8 is just about as fast as the Mossie on the deck, and both are pretty close at the relevant altitudes.

 

In terms of performance as a fighter, don't expect it to be a Spitfire. On the other hand, everyone expect it to be a dog and they are in for a nasty surprise. An FB.VI without bombs and less internal fuel than what is required to fly from England to Berlin and back, will have a lower wing loading than all the LW birds we have. In terms of power loading it is about equal to the P-47/190A8 depending on fuel loads of course. The stall speed is lower than all 190s and the roll rate at dogfighting speeds, while not stellar is quite adequate. I have only played with FB.VI in one other game/sim that has very good flight modeling and there the FB.VI will eat any 190D9 or 190A8 that will try to turn with it at low altitudes. I made a living there from 190/109/P51s etc that disrespected the Mossie as a fighter and went in for what they perceived as an easy kill. The 190D9 are dangerous if they play it safe and keep to BnZ you from advantage.

 

In a many-on-many dogfight, situational awareness and firepower are the main requirement for success, more than turning or top speed - historically SA was greatly boosted by having a navigator/observer, often not relevant in DCS (unless you plan on multi-crew regularly). Firepower allows you to cash-in on a gun solution and finish the fight with one burst. Not having to follow the opponent in prolonged turns and slowly peck at him to pieces is huge. 4 Hispanos in the nose, plus excellent over-the-nose view (no engine, no prop there) will make even high deflection shots possible and deadly.

Edited August 14, 2021 by Bozon

[DD_Fenrir]

That 5 for 5 engagement being referenced is I suspect from the Banff strike wing, in which case their opponents would have been Fw 190A-8s from JG5.

 

From reports I have read, the Mossie should be just barely even (though not quite) with an Fw 190A-8 a in a traditional turn fight; however, I suspect this is probably in the first half of a 180. The Mossie is heavier and I suspect will bleed speed mightily as the turn prolongs. Acceleration of the Fw is good, though how the Mossie compares...? Power loading is similar and the Mossie nudges ahead on wingloading but induced drag is key in the turn fight, and will remain to be seen.

 

As for K-4s? I suspect they'll have few issues, being able to out turn and out climb the wooden wonder, but the Mossie could still be dangerous if taken for granted. Those 4 x 20mm could punish you severely if you push a bad position or get too low on energy.

 

The D-9s will be half way between - don't turn with it, keep your speed up and BnZ his ass. Standard D-9 M.O.!

 

Summary? Mossie will be required to be respected and may surprise a few erstwhile DCS Jagdwaffe flyers who may be expecting an easy kill.

 

 

Edited August 14, 2021 by DD_Fenrir

[Robi-wan]

7 hours ago, Drakeshoot said:

if so, will the Mossie be viable in it’s FB role and, more importantly, how should it be fought? As an energy fighter, boom & zooming or a turn fighter with those lovely merlins dragging it round the corner, or do we leg-it and come back with a load of mates with sticks? 

 

Bear with me, you might find it useful (or not). If you believe the AFDU evaluation of the FB.VI (and I do) then we'll be flying a +3 g airplane.

 

If you also accept the Pilot Notes, we're saying the airplane has a 1 g stall speed in the clean (gear and flaps up) configuration of ~105 KIAS. The airspeed indicator has a plus or minus 2 to 4 knots error. So it's about 105 KIAS in wings level unaccelerated flight. 

 

It just so happens that at 70 degrees angle of bank (whilst maintaining altitude) you will require ~3 g to hold altitude. Great...so what?

 

Notice our indicated stall speed went from 105 KIAS up to 178 KIAS. Okay fine...so what, you ask.

 

Perhaps you will recall off the top of your cranium that corner velocity is the minimum speed that you can pull maximum g. See where I'm going with this? Corner velocity for the Mosquito should be just a bit faster than 178 KIAS, so let's call it 180 KIAS.

 

At 180 KIAS your 3 g turn radius will be ~1000 feet and the diameter ~2000 feet. You can't fly any slower and pull 3 g because you will stall. What about flying faster?

 

At 260 KIAS you have more than doubled your turn radius and diameter. IRL fighter pilots talk about turn radius (not diameter). 

 

APOLOGIES FOR A BUSY GRAPHIC

 

This chart is taken from Aerodynamics For Naval Aviators (I was an Air Force guy), the yellow lines are at 70 degrees because for the sake of discussion, we agree that the FB.VI is a +3 g airplane. The lime green line is for 180 KTAS (Indicated is close enough True at Sea Level) radius and rate. The blue line is for 260 KTAS radius and rate. Start at the bottom with your airspeed and move up vertically until you intersect the first yellow line, move horizontally to the right to get your turn radius. If you continue vertically to the second yellow line then move horizontally to the right will give your turn rate.

 

The takeaways? Flying at a corner velocity of ~180 KIAS will generate a turn rate of 17 degrees per second. Flying at 260 KIAS will lower the turn rate to 12 degrees per second. 

 

 

And finally this is what AFDU had to say about the FB.VI against Spitfire and Typhoons.

 

[Robi-wan]

8 hours ago, Drakeshoot said:

I’ve heard an interesting urban myth about the Mossie and would love to hear from people more knowledgeable, that there was a significant gap (20-40kts) between takeoff speed and controllable single engine speed, so that the loss of an engine shortly after rotation would result in the surviving Merlin producing more torque than the controls had authority to counteract resulting in uncontrollable roll, likely inversion and almost certain death. 

 

Yes to this.

 

According to David Ogilvy in The De Havilland Mosquito Chapter 5, he describes a normal takeoff as using +9 lb of boost and 3000 RPM (full fine prop pitch) then lifting off at around 100 KIAS then to accelerate close to the ground (in ground effect) as fast as possible to 175 KIAS which he calls "asymmetric safety speed." He says "often it is possible to reduce power to +7 lb and 2650 RPM, in which case it is practicable and safe to start the climb at 155 knots."

 

In modern terms he's describing a very high Vmca (Velocity minimum control air), general aviation twin engine airplane pilots in the USA refer to this as the Blue Line on the airspeed indicator. 

 

Generally speaking, pilots when faced with an engine failure on takeoff would often pull both throttles to Idle and raise the gear to get the airplane stopped safely. The records of squadrons are full of entries noting engine loss of power or failure and raising the gear to stop.

[Ercoupe]

Wow....unflattering, to say the least. If you like to dogfight, this isn't going to be your airplane. But, to be fair, that's not what it was designed to do. 

[Robi-wan]

5 minutes ago, Ercoupe said:

Wow....unflattering, to say the least. If you like to dogfight, this isn't going to be your airplane. But, to be fair, that's not what it was designed to do. 

 

Exactly. If folks are using the IL-2 1946 Mosquito as their exemplar, they will be unhappy. 

[gavagai]

6 hours ago, DD_Fenrir said:

Summary? Mossie will be required to be respected and may surprise a few erstwhile DCS Jagdwaffe flyers who may be expecting an easy kill.

 

Emphasis on "a few."

 

[Drakeshoot]

Superb breakdown Robi-wan, the ADFU evaluation appears to be for the Merlin 23 version though, I wonder if the addition of an extra 220bhp a side will make much of a difference. I also read somewhere that the T&E Mossie was found to be significantly underperforming vs type, though I’m not sure at what stage. 
 

All food for thought, keep it coming. 

[Krupi]

The Merlin 25s slightly improved the max speed however it massively improved the climb performance. See the conclusion in the attached document. 

 

Mosquito-VI-tactical.pdf

[fjacobsen]

I think the Mosquito should be regarded more as a Fighter bomber than a Fighter.

I expect to use it for low level pinpoint bombing missions aka the missions it flew in reallife against Gestapo Headquarters and the like.

It will also be good for interdiction missions.

 

It can also be used for reconnaissance and weather intel, though such missions sounds boring in a combat flight sim enviroment.

 

Fighter vs fighter engagemnts would mostly only occur  as an defensive action when cought be surprice.

[Mogster]

5 hours ago, Robi-wan said:

 

 

Generally speaking, pilots when faced with an engine failure on takeoff would often pull both throttles to Idle and raise the gear to get the airplane stopped safely. The records of squadrons are full of entries noting engine loss of power or failure and raising the gear to stop.

Sounds dicey with a full load of ammo, bombs, RPs.

[Drakeshoot]

Does anyone know if the RPs are the same as carried by the Typhoon? I recall another apocryphal story about a load of Tiffie RPs having the same effect as a 15” naval shell or something?

[Mogster]

8 minutes ago, Drakeshoot said:

Does anyone know if the RPs are the same as carried by the Typhoon? I recall another apocryphal story about a load of Tiffie RPs having the same effect as a 15” naval shell or something?

They are the same RP-3 or 60lbs rockets. There were many different types of warhead though I think.

 

 

 

 

[Robi-wan]

1 hour ago, Drakeshoot said:

I wonder if the addition of an extra 220bhp a side will make much of a difference.

 

 

No it should not, the weight in the elevator is still present thus limiting how many g you can pull; and it's the same wing so same stall airspeed. The Merlin 25s give it a little more power.

 

1 hour ago, Krupi said:

The Merlin 25s slightly improved the max speed however it massively improved the climb performance.

 

 

The conclusion is addressing a climb from naught height to ~2000 feet. Where the Merlin 23s edit Merlin 25s provide something a little better than ~4000 fpm (2000 feet in less than 30 seconds equals > 4000 feet in 60 seconds). I'm not sure I'd conclude that Merlin 25s massively improved climb performance based upon #8 "The good climb at full power allows the Mosquito an excellent chance of reaching cloud cover quickly. I'm just saying without some idea of the time required [edit the single seat test when stripped of 1500 pounds climbed at >3000 fpm], all I'd conclude is that's it's better.

 

You could be right that it's massively better. 

 

Edited August 15, 2021 by Robi-wan

[Bozon]

@Robi-wan, that ADFU initial report used the worst possible FB.VI, with Merlin 23s max +14 boost and I suspect exhaust flame dumpers as well. The fact that it was out-paced by all except Spit-V really makes you wonder.

 

The later trial that @Krupi attached tested a much better Merlin 25 with +18 boost and that one out-paced a Griffon Spit XII which was used to run down 190As that were doing low level attacks on the coast of Britain.

 

ADFU has several reports that make you wonder about their judgment. Their 3G comment is super odd - the plane would not see action if it could only pull 3G coming out of a dive or in a defensive break turn. You should read their report about the P-47 trials. They absolutely hated that plane, and it ended up all right, so did the Mosquito.

[Drakeshoot]

Interesting Bozon, I’ve read a number of books by fighter pilots from WW2 to Sharkey Ward, almost all of whom held the test branch’s conclusions in some degree of distain, if not their courage. Possibly a result of knowledge gained in battle, possibly faith/pride in their steed or most likely a blend of both. 
 

 

 

[Robi-wan]

@Bozonwe both have read the ORBs and books where average line pilots managed to outrun bandits (with the benefit of a timely tally) and reports of similarly skilled pilots getting gunned. SOP for Day Rangers was to have sufficient cloud cover in order to escape into cloud. ORBs frequently report these sorties were abandoned for lack of cloud cover. Likewise Coastal Command SOP was to turn out to sea if a gaggle of SE fighters was spotted in time. The point being, avoiding a maneuvering fight with SE fighters was baked into their tactics regardless of whether their airplanes had Merlin 21s, 23s or 25s. I also recognize that the AFDU was not the Empire Test Pilot School, and planes were flown imprecisely. Their results and recommendations subject to change.

 

We're getting Merlin 25 motors in the sim, I love that. Given that MP servers will more than likely cater to day VFR single engine 1GCCFPs, I suspect that guys and gals in their Mosquito will not be adopting WWII tactics. And getting killed by 109s and 190s will be a common sight.

 

That's just my opinion. 

[Krupi]

@Robi-wan

 

Given that some Axis players still try and turn with a Spitfire even when they know better I think that is a safe assumption, I fully expect to see many a Mosquito FB plummeting from an altitude that they have no logical reason to be at 

 

I also expect to be abused for "Vulching" an enemy airfield... But they are just going to have to get used to it 

[Bozon]

17 minutes ago, Robi-wan said:

@Bozonwe both have read the ORBs and books where average line pilots managed to outrun bandits (with the benefit of a timely tally) and reports of similarly skilled pilots getting gunned. SOP for Day Rangers was to have sufficient cloud cover in order to escape into cloud. ORBs frequently report these sorties were abandoned for lack of cloud cover. Likewise Coastal Command SOP was to turn out to sea if a gaggle of SE fighters was spotted in time. The point being, avoiding a maneuvering fight with SE fighters was baked into their tactics regardless of whether their airplanes had Merlin 21s, 23s or 25s. I also recognize that the AFDU was not the Empire Test Pilot School, and planes were flown imprecisely. Their results and recommendations subject to change.

 

We're getting Merlin 25 motors in the sim, I love that. Given that MP servers will more than likely cater to day VFR single engine 1GCCFPs, I suspect that guys and gals in their Mosquito will not be adopting WWII tactics. And getting killed by 109s and 190s will be a common sight.

 

That's just my opinion. 

Yes of course in MP most of us do not follow historical tactics - often time not even logical tactics… I for one will be throwing it into dogfights, because this is what I do, not because it makes sense. Sure, I’ll die a lot, but if I go down flaming, I want to go down in the most gorgeous plane in history.

 

As for historical tactics and the cloud cover - the fear of day rangers was to be caught in a prolonged dogfight. Even if they win, they still need to be able to fly 400 miles to get home, and you don’t want to do that at full throttle all the way with enemies on your tail, while additional fighters are being vectored in to intercept you.

 

An equal fight with 50% chance of winning (where losing means dying/being captured) is not good enough. This is a huge attrition rate. From interviews with veterans, day rangers were briefed to attack fighters only when they had the advantage, being surprise, numerical, or position, and to disengage the moment the advantage is lost. A low cloud layer offers a quick way out of the fight, and combined with an initial advantage increased the chances of RTB to a point where risking an attack on a fighter was worth it.

[Mr_sukebe]

I really don't see the Mossie FB being able to take on a reasonably well piloted D9 or K4 in a one on one.

Picking off fighters that it can take by surprise, sure.  

 

What I see it being very good at is intercepting and destroying enemy bombers.

[Krupi]

1 hour ago, Mr_sukebe said:

I really don't see the Mossie FB being able to take on a reasonably well piloted D9 or K4 in a one on one.

Picking off fighters that it can take by surprise, sure.  

 

What I see it being very good at is intercepting and destroying enemy bombers.

 

Which is precisely the role in which the Night Fighter version was enrolled.