Now witness the firepower of this fully armed and operational battle station

[Lusche]

The DB603As make roughly half as much power at 30 kft.  I'm not sure if I have info to make a powerloading comparison with other planes in AH at 30 kft. The overall numbers aren't flattering, but you've basically got powerloading halved (very roughly) from sea level power, and only ~10% penalty from a standard cfg (the basic 2x12.7mm + 2x20mm) to heaviest (BK5), and 5% penalty from 6x20mm or 2x103 to a BK5 loadout.  So really not much difference across the board.

I'm thinking 410 because the expense in setting up a few passes seems possibly worth the benefit of the 410's extra firepower. As long as the B-29 is no faster than the interceptors considered, I think it's doable.  I expect (been out of the game forever, so don't recall exact numbers, only overall trends) a 410 doing a few dozen MPH more than a B-29 is still manageable.  It's only with really slow interceptors (e.g. B25H) that you really don't get more than a few passes and then get helplessly get left behind.

What the overall picture looks like is a lot like the standard Luftwaffe MO - only as much effectiveness from the plane as the pilot provides in discipline.

A few dozen mph speed advantage at an altitude like that makes catching and setting up an attack on a B-29 very, very difficult. If the bomber pilot is on guard, he can quite easily make it even more miserable for the fighter pilot with a few evasive moves.  Even a B-17 at 30k can already do that with many fighters in game. Also, an (optimistically) assumed 40 mph speed advantage means the attacker needs almost a sector to close in from 6k to firing distance in a tailchase for example.

IMHO the fighters really suited to be used against very high 29's are: P-47M&N, Spit 14, 109K-4, Ta 152, F4U-4, and to some extend the 262 (which is already struggling at 30k)

[Lusche]

A very quick and dirty chart, showing max speed & climbrate @30k of a few fighters. These values had been taken from the AH web plane comparison page.





I have set the Y axis to meet the X axis at 348 mph (expected top speed of the B-29 according to the posted performance charts). It's important to note that particularly the mil climb rate can be much lower due to fuel state - for example when first time reaching 30k during climb, the Me 262's actual climb rate is less than 600, significantly lower than given on the table.


Of course there is more to fighter performance as a high alt B-29 buster... firepower, ruggedness, energy retention at high altitude and so on. But it can give a first impression

[Wmaker]

I found data for the 410A-1/U2 doing 390mph@ ~22,000ft and only 375 mph at 25,800ft. So I'd guess it will be significant slower than that at 30k, and that's without  a heavy Mk 103. According to the chart AKAK posted some time ago, the B-29 had a top speed around 348mph at that altitude.

And that actually seems to be knots instead of miles...  

http://bbs.hitechcreations.com/smf/index.php/topic,299570.0.html

...at least it mentions "kn" as the unit.

That's 400mph right there...

It's true that the "common" figure I've always attached with the B-29 is 357mph@25000ft. At 5000ft higher the air resistance is obviously less and I've read that the turbos were able to maintain sea level hp up to 33000ft (I have to say I found that quite surprising. ).

[Lusche]

And that actually seems to be knots instead of miles...  

ooops 

[Plawranc]

I believe this is in order 

[moot]

Lusche-

Well MIL is probably negligible for the purpose of this comparison.

I've vectored B17s with a 25H almost successfully (killed 2 planes of 1 formation).  There's basically no margin for error - you get two passes and you're done*.  Obviously it's not feasible to consider chase interception where you're counting on catching up.  But the 25H comparison is important because it shows even with that substantial handicap, you still get 2 passes.  It takes practice, but then so does proper bomber interception, so that's nothing new.

*You get some tail shot time with the 75mm which is probably comparable to what you'd get with a 410-mounted BK5, but that's a separate thing.

So vectoring is feasible, in principle.  I'm not arguing chase interception, but as said above: that the trade-off between extra firepower and less speed should make it worthwhile if vectoring happens to be an option (e.g. country chat gives you bomber info to vector with).
There's two pieces to the trade off: speed and firepower.  I don't have the speeds myself (could retrieve from AH plane comparison charts) nor the powerloading numbers (need engine power vs altitude curves), but I can quantify the firepower factor... Once I find some docs I remember working on a while back...

Another reason I consider this worthwhile is that with (admittedly the worst example, but illustrating the point that much more) a fast but under-armed interceptor, you're betting on multiple passes of relatively low damage, instead of a few passes of relatively high damage.  The implicit difference is that you're potentially taking that much more damage with each pass, which in the case of the B-29 isn't negligible.  Especially not if you're flying something like a Spitfire or radiator-happy 190D9 and 152.  The Zerstörer vector scenario, although unforgiving speed-wise, is a better bet in this respect.

edit- 400mph @ 30k or so.. Yikes.

[Colt44]

Can I keep it....I promise to feed it every day...       

[moot]

Alright, so on a 0.75 second firepower basis, just a pair of MK-103 beats every gun package in the game except the heavy 110G and A8 packages.  Using Tony Williams' power formula, fired for 3/4 of a second, you get:

Package	Power
110G	1483
410: 2x151+2x103	1260
A-8: 2x30	1213
410: just 103's	990
410: 6x151	810
Ta 152	741
Mossie	700
190A-8	612
109K-4	543
410: just the BK5	453
Spit XIV	410
190D-9	342
P-38	295
P47-M	240
P-51D	180

And that's assuming everything hits.  If you consider the ballistics involved, the 50 cal packages are more flexible, but then so are the MK 103 packages which have basically the same ballistics (except for lower ROF: bigger hit% penalty); while the 110G (4x20+2x30) is no more effective than the 410's 6x20 package due to the 108s being way too limp ballistically.  Same deal with the A8's 30mm package (and Me410's 151+103 package to a lesser extent, cf "just 103's" instead) - it requires you fly that 190A8 that much further and longer into the B-29's defensive bullet stream instead of staying as far as .50cal or hispano or MK 103s allow. 

The BK5 is all or nothing: roughly half of the best damage dealt realistically by any other package, in a single shot from at least as far as any other package could manage.

Overall, I think the 410 as B-29 interceptor is very arguable anytime vectoring is an option.  I don't think Spitfires, 190D/152 are going to be too attractive due to how easily damaged they are.  The 152 is kind of an option if you put its extra high-altitude agility to use... But again I don't think that's enough to make a difference unless we've got multiple 152s attacking one B-29 formation; then it's probably much less arguable that the 152's clearly the best.  Only the 47M looks comparable, and I have no idea what its agility is like to compare it with the 152's agility/firepower.

F4U4, 262, 109K, all of them look about the same as the 152 - a mix of good and bad qualities.  F4U lacks firepower to go with its durability; everything else is average. The 47M looks like basically a better F4U4.  262 has everything except speed/agility, and big engine vulnerability. 109K has too little firepower.

What else is there?  The Yak 9T IIRC has pretty bad high altitude performance.  Tempest/Tiffie?  I don't recall what they're like.  Don't recall N1K either.

..
If you reduce firing time, the 103 gets even better. A single shot from a pair of 103s gives 200 points damage, compared to half that for a tap of the trigger in the Mossie or 152.

[BillyD]

Tony Williams' power formula

wasnt that a jazz fusion project in the 70s?

tony williams ftw   

[moot]

Before my time..   I'll have to look it up.

[Lusche]

<snip>

I'm aware of the advantages of heavy firepower and the pro's and cons of the different weapon packages. And of course a minimum firepower is necessary against such a target, and the more you can bring along, the better.
But the main problem is indeed getting that firepower to the target, and there is a point when the efficiency of the guns is more than offset by the deficiencies of the weapon's platform performance.

And here the 410, as well as some other heavy armed fighters like the 190A-8 run into trouble if the B-29 runs at full power at 30k. Distances and reaction times are relatively short in the MA. Getting dependable vectoring is often a matter of pure luck. And if you are lucky and get visual contact, you have to get into a favorable attack position. An assumed speed overhead of 30-40 mph (if at all) is in my experience (and I dare to say I have quite a lot both in bombers as well as fighters at such altitudes) very, very little. It will take a long time to get into position and as a bomber pilot it is easy for me to do a few counter maneuvers. The meager climb rate / acceleration of the 410 means that it will have even more trouble to set up another attack run.  
The firepower is tremendous, but so are the problems getting it to bear (and I didn't even mention possible escort fighters
Against medium to high B-17 raids, the 410 would probably do fine. Against a 30k B-29 blazing along at full power, it will, for all practical purposes, suck. Yes, you can get kills, but there are other fighters that can fill that role more efficiently giving the realities of the MA combat environment.

There's a reason why you do not see B-25's, and only very very few 110's and Mossies attacking the big Titanic Tuesday bombing missions, even though there is much more warning time and much better vectoring information available than usual.

.  Only the 47M looks comparable, and I have no idea what its agility is like to compare it with the 152's agility/firepower.

The 47M is a great plane at altitude. It really shines up there. I only do not fly it as much because I prefer a german cannon package which is better suited for my tactics.

[RTHolmes]

the meteor would be perfect for B29 intercepts

 

[sunfan1121]

Remember Lusche, this is moot were talking about. If he wanted to kill B29's with a c202 he would find a way.

[Lusche]

Remember Lusche, this is moot were talking about. If he wanted to kill B29's with a c202 he would find a way.

Which still wouldn't make the C202 a viable interceptor choice in general 

[moot]

Lusche that's not how I remember it.

Can the other lighter fighters better stay in touch with fast bombers?  Yes.  But for correspondingly less damage dealt to those bombers, and more damage taken to boot.

I also don't think I agree with how useless/uneffective you're characterizing vector (as opposed to chase) intercept.  I don't remember having any trouble at all getting at least a few passes on formations with slower planes like the 110 or Mossie.

I'm not arguing that the 410 is the best.  I expect the 152 and 47M will be the top choices for a high alt B-29 intercept.  But if you can manage something like 4-5 interceptors, and there's only a few B-29s to hunt, I think something like a 410 is comparable to 4-5 152s or 47Ms due to how much more powerful it is.
I don't think this firepower advantage would hold in a swarm scenario like TT bombing missions.. But then again if you've got the benefit of an attacking swarm, you can probably get a few kills before being outrun.

And again, if you're either outrun or full of holes after a few passes then you might as well pick something that'll give you a max of kills in that short interval.  Because I don't think something that has both more speed and more firepower than a B-17 is going to make it any easier for the 152 whose radiator dies so easily, and the 47 which has to stay locked on solution so much longer for its 50cals to really work.

Escort fighters - No argument, I think that'd be bad news for those zerstörer types.  But again what do you get with 152s or 47Ms when the criteria is B-29 kills?  I already hated B-17s' defensive guns, I can't imagine that it's going to be much fun with a faster, stronger, and better defended target.

Provided the performance numbers I have are correct, I'm still putting my money on a heavy 410 using historical few-passes max-damage tactics. 

Remember Lusche, this is moot were talking about. If he wanted to kill B29's with a c202 he would find a way.

  Right. 
I'd definitely take a 25H to fly HO thru a bomber mission, given enough time to set up for it.  No doubt about it.