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View Full Version : A20C vs. P38L Late. This cannot be right.



ElAurens
10-05-2007, 10:54 AM
Was doing the tactical thing last night on the WarWings server with my wing man BlitzPig_Frat.

I was astonished at how slow the P38 was down low.

The scenario...

A20C: 50% fuel, 1x1000lb bomb and 4x300lb. bombs, 90% throttle, 100% prop, "radiator" 4.

P38L Late: 50% fuel, 2x1000lb bombs, 10xHVAR, 90% throttle, 100% prop, "radiator" auto.

Altitude flown 1500ft.

Speeds:

A20C: 270mph IAS

P38L Late: 220mph IAS.

http://forums.ubi.com/images/smilies/blink.gif

JG53Frankyboy
10-05-2007, 10:56 AM
well, the A-20 has all these bombs internal....
and in auto, the rad was most propably full open in the P-38

Daiichidoku
10-05-2007, 11:13 AM
the Havoc has only 200 pounds more ordinance, not counting the 38s TEN HVARS

find out how much an HVAR wieghs, then get back to us

bear in mind, the 38 late is what? 17,000-18,000lbs? cant be too far off what a Havoic weighs

Brain32
10-05-2007, 11:22 AM
Originally posted by ElAurens:
Was doing the tactical thing last night on the WarWings server with my wing man BlitzPig_Frat.

I was astonished at how slow the P38 was down low.

The scenario...

A20C: 50% fuel, 1x1000lb bomb and 4x300lb. bombs, 90% throttle, 100% prop, "radiator" 4.

P38L Late: 50% fuel, 2x1000lb bombs, 10xHVAR, 90% throttle, 100% prop, "radiator" auto.

Altitude flown 1500ft.

Speeds:

A20C: 270mph IAS

P38L Late: 220mph IAS.

http://forums.ubi.com/images/smilies/blink.gif

220MPH = 354KMH
Are you sure you had BOTH engines on?

Urufu_Shinjiro
10-05-2007, 11:27 AM
Those rockets and thier mounts cause a LOT of drag on the P-38.

LEBillfish
10-05-2007, 11:30 AM
I'm curious.....Though after one of our previous patches prop pitch was hosed for all planes (meaning you get more speed from higher PP), I still tend to run at around 85% PP, down to 80% for cruise, and 90 for combat power....Partly this allows for lower rpm, hence running cooler...So rads normally at 4-6 dependant on the plane I can fly all day....

So why run at 100%pp where your rads might be full open and very possibly (considering old way it worked and seems to some still)....Loss of speed from a finer pitch screw?

Kurfurst__
10-05-2007, 11:46 AM
Originally posted by JG53Frankyboy:
well, the A-20 has all these bombs internal....
and in auto, the rad was most propably full open in the P-38

Bingo... Now, I can`t tell wheter the drag from external stores is correct or not, but for example on the 109G a single 250 kg bomb plus rack under the fuselage chopped of - 40 km/h... Weight has very little role in here.

I'd not be surprised if those HVAR 'bundles' are causing a massive drag hit..

Korolov1986
10-05-2007, 11:51 AM
HVAR trees on the P-38 are killer. Throw in a couple 1000lb bombs and you have a lot of weight - more than A-20.

Throttle might also be the culprit here, as I've found the P-38's throttle under 100% to be lacking.

Cajun76
10-05-2007, 12:06 PM
Just tried on the Okinawa QMB, the P-38L was doing 270+ @ 90%.

http://img.photobucket.com/albums/v30/Cajun76/grab0000.jpg

I can do better than 220 with combat flaps deployed.

Speed brake? http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Choctaw111
10-05-2007, 01:20 PM
The rockets and bombs on the 38 cause a lot of drag. The A20 was carrying all of those bombs internally. That makes a BIG difference. The A20 is a real speed demon in Il2, especially for what it can carry, it's forward firing guns and it's defensive armament. The A20 is a real winner! http://forums.ubi.com/images/smilies/25.gif

ploughman
10-05-2007, 01:48 PM
Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JG53Frankyboy:
well, the A-20 has all these bombs internal....
and in auto, the rad was most propably full open in the P-38

Bingo... Now, I can`t tell wheter the drag from external stores is correct or not, but for example on the 109G a single 250 kg bomb plus rack under the fuselage chopped of - 40 km/h... Weight has very little role in here.

I'd not be surprised if those HVAR 'bundles' are causing a massive drag hit.. </div></BLOCKQUOTE>

Drag has always seemed to me to be a bit of an Il-2 weakness. Radiators don't cause the drag they should and aircraft deceleration isn't what it should be as a result either, planes coast like they're frictionless and some aircraft, like the A6M, just float around like helium balloons. Those rocket trees should slow it down, and should be causing the hit you say, but something tells me that they're not the culprit in this case.

ElAurens
10-05-2007, 02:44 PM
Interesting.

BTW the speed brake was not deployed, and I was very careful with my elevator trim.

I realize there is a drag hit with the external stores, but honestly someting odd is going on here. We were on the "Northern European" map BTW.

Once bombs and rockets were expended 320mph IAS with the same settings was easily done. It seems odd that a 100mph IAS difference is incured with the external ordinance. Of course 90% may be a vastly different BHP out put on the two aircraft as well. The Wright R2600s on the A20 are of about 1700BHP depending on version. I believe the L Late is around that as well.

More investigations this evening.

Kurfurst__
10-05-2007, 03:09 PM
Originally posted by Ploughman:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JG53Frankyboy:
well, the A-20 has all these bombs internal....
and in auto, the rad was most propably full open in the P-38

Bingo... Now, I can`t tell wheter the drag from external stores is correct or not, but for example on the 109G a single 250 kg bomb plus rack under the fuselage chopped of - 40 km/h... Weight has very little role in here.

I'd not be surprised if those HVAR 'bundles' are causing a massive drag hit.. </div></BLOCKQUOTE>

Drag has always seemed to me to be a bit of an Il-2 weakness. Radiators don't cause the drag they should and aircraft deceleration isn't what it should be as a result either, planes coast like they're frictionless and some aircraft, like the A6M, just float around like helium balloons. Those rocket trees should slow it down, and should be causing the hit you say, but something tells me that they're not the culprit in this case. </div></BLOCKQUOTE>

... Looking at the leaked files of the Il2 engine, I suspect the FM is using some kind of a 'generic' aerodynamical formulae, with some fixed points being given to the program to adjust the whole curve to them. This may be blamed for problems modelling very specific conditions. The most noteworthy to me being the radiator`s drag effect on climb - or rather, the total lack of it..

It would not surprise me if the external stores stuff would be generic, too, or if planes with external stores would be a different FM each to start with..

VW-IceFire
10-05-2007, 03:21 PM
Originally posted by ElAurens:
Interesting.

BTW the speed brake was not deployed, and I was very careful with my elevator trim.

I realize there is a drag hit with the external stores, but honestly someting odd is going on here. We were on the "Northern European" map BTW.

Once bombs and rockets were expended 320mph IAS with the same settings was easily done. It seems odd that a 100mph IAS difference is incured with the external ordinance. Of course 90% may be a vastly different BHP out put on the two aircraft as well. The Wright R2600s on the A20 are of about 1700BHP depending on version. I believe the L Late is around that as well.

More investigations this evening.
The A-20's are fast for being bombers but I think the focus here would be on the P-38 and what you did to it http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

When I do fly the P-38 its usually with external stores of some kind and its normally not that slow. You should be able to out power a A-20.

Grand_Armee
10-05-2007, 03:57 PM
Having not flown a REAL p-38 I can't say what it should be doing. But I've always found it in IL-2 to be slow. I thought it was supposed to be a speed demon. Though I do remember a German ace on a documentary saying it was almost as easy to shoot down as an me-110.

And the A-20...that thing is so good, you wonder why it was ever replaced. But then you remember this is a game. It's still hard to BnZ because it's so fast it gets out from under you and ends up ahead of you with it's gunners putting holes in your precious toy.

I have a threory that anything Russian or lend-leased to Russia gets the Oleg 'bonus'.

DKoor
10-05-2007, 03:58 PM
Crimea, 12 o clock, 100% fuel, alt 10m, l0adout: 10x5in HVARS + 2x1000lb, rad closed.
CEM full, physics full.

P-38L_LATE 535km/h

http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

JG53Frankyboy
10-05-2007, 04:05 PM
just to compare:
Spitfire IXe
in default i can reach about 535km/h TAS at SL (crimea map)

with an empty fuselage bombrack its about 525km/h

with empty fuselage AND wingracks its ~500km/h !!


also using Droptanks in a P-51 is no good idea........ after releasing them you are around 30km/h slower !


the nice thing with the P-38s is, that you are can fly as fast after you released the bombs as you would fly in default http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif
but, never take any rockets, they will slow you down !

DKoor
10-05-2007, 04:15 PM
Same setup, but in this scenario I've fired/released ALL ordnance (HVARS, bombs) then measured the speed.
I've reached 596km/h at sea level with the P-38L_LATE, which makes this fighter mighty powerful speed wise.......it achieved that with tree rackshttp://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

ElAurens
10-05-2007, 04:36 PM
Gents, do remember that my speeds were done at 90% power. We tend to use that as a "combat cruise" setting. I know I could go faster by advancing the throttles, but that is not what I'm getting at.

JG53Frankyboy
10-05-2007, 04:50 PM
Originally posted by ElAurens:
Gents, do remember that my speeds were done at 90% power. We tend to use that as a "combat cruise" setting. I know I could go faster by advancing the throttles, but that is not what I'm getting at.

well, some planes in game have
100% only
others have
100% + W button
others
100 + 110%
others
100 + 110% + W button

some planes do overheat at 100% power + 100% pitch with coolers open.
others dont overheat at 103% + W cooler open.
others dont overheat at 110%poer + 100% pitch cooler open.

the planes are programmed with too different standards to compare with these setting and name them in general "cruising"......... <-my opinion.

msalama
10-05-2007, 04:53 PM
or if planes with external stores would be a different FM each to start with..

Kinda wouldn't make sense from a programming POV. That said the generic drag modelling can still very well be a slap-it-on for every flyable, so...

But then who the hexx said this is a real simulation in the 1st place, eh http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

An interesting discussion this, BTW. S! all.

DKoor
10-05-2007, 05:07 PM
Difference tree rack/without tree rack is 1km/h http://forums.ubi.com/images/smilies/partyhat.gif

Same as P-47.......... difference center rack/wo center rack is exactly 1km/h.

Great drag!

msalama
10-05-2007, 05:11 PM
And you measured this just now?

DKoor
10-05-2007, 05:13 PM
http://forum.1cpublishing.eu/viewtopic.php?t=126

msalama
10-05-2007, 05:20 PM
Cheers Kuna. Great stuff, plus a s**tload of work you've done.

~S~

msalama
10-05-2007, 05:30 PM
So OK, those speeds are on the deck unless otherwise mentioned... how much do they differ from the RL data you've come across, ye bookworms then?

Enquiring minds just asking mind http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

DKoor
10-05-2007, 05:46 PM
Thanks. Personally I don't know how much they differ from rl, but from my limited knowledge about rl speeds, I can tell that more or less all fighters have boosted speeds a bit. Little above their rl values.

ps. I didn't uploaded all tested speeds, there is more.....but when I come back from my trip (two days or so) I'll correct that too http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

mortoma
10-05-2007, 07:23 PM
I fly the P-38J with all that stuff hanging out and I can go much faster than that down low. Something must have been wrong indeed.

mortoma
10-05-2007, 07:34 PM
I just duplicated his scenario in QMB in the Okinawa map and instead of 50% fuel, I had full fuel. At 1500ft. with everything else the same, including stores ( P-38L Late ) I was easily getting 270mph IAS. This translates to 240kts. So something was wrong somewhere. I mean if I got faster than he did with full fuel and not half fuel.

Gibbage1
10-06-2007, 01:09 AM
Try the rockets on the Me-262. It takes about 100MPH off the top speed.

I dont know why, but external loads are crazy draggy in IL2. Im not suprised that a P-38 with the HVAR's and bombs are like that, and I cant say its very wrong. I dont know of any speed testing done with them on.

DKoor
10-06-2007, 01:38 AM
The funny part of it all is, while some racks in fact create noticeable drag, we have other racks which create no drag. That is, if we disregard 1km/h. I plane to test some of those and I'll probably post results soon.
I really did not know that R4Ms create such drag....http://forums.ubi.com/groupee_common/emoticons/icon_confused.gif

ElAurens
10-06-2007, 02:16 AM
I know it will go faster with more power, that is not my point.

My observation was quite simple.

Two of us ran our A20Cs and then P38L Lates exactly as I described in the first post. At identical power settings of 90% throttle, not 100%, not at WEP, the A20C was 50mph IAS faster than the P38L Late on the Northern Europe map. Both of us had the same result. It was online, not in QMB, not on Crimea, and we were not making a max speed test.

Now I don't know about you, but I find it rather odd that the A20 cruises 50mph faster than the P38 L Late at 1500ft. at 90% power.

I'm sure this is not reflective of real life performance.

UBI Zoo indeed.

p1ngu666
10-06-2007, 03:05 AM
did the p38late have the extra performance all crammed into wep?, some planes had that with a really odd powercurve.

a20's where replaced by b25-mossie, b25 can carry slightly more bombs, much more effective defensive armament (espicaly ingame).

mossies just pwned irl

DKoor
10-06-2007, 06:22 AM
Originally posted by ElAurens:
I know it will go faster with more power, that is not my point.

My observation was quite simple.

Two of us ran our A20Cs and then P38L Lates exactly as I described in the first post. At identical power settings of 90% throttle, not 100%, not at WEP, the A20C was 50mph IAS faster than the P38L Late on the Northern Europe map. Both of us had the same result. It was online, not in QMB, not on Crimea, and we were not making a max speed test.

Now I don't know about you, but I find it rather odd that the A20 cruises 50mph faster than the P38 L Late at 1500ft. at 90% power.

I'm sure this is not reflective of real life performance.

UBI Zoo indeed. Great!

P-38L_LATE at your setup from 1st page
472km/h TAS, 280mph IAS

A-20C at your setup from 1st page
463km/h TAS, 270mph IAS

So.
You troll here and then call it UBi zoo when people can't understand wtf are you talking about?
You just set the UBi "zoo" bar higher, man.

ps. In case you weren't trolling, then..... disregard what I wrote above but then you have some very hard work/practice to do with this game.

DKoor
10-06-2007, 06:23 AM
Originally posted by p1ngu666:
did the p38late have the extra performance all crammed into wep?, some planes had that with a really odd powercurve.

a20's where replaced by b25-mossie, b25 can carry slightly more bombs, much more effective defensive armament (espicaly ingame).

mossies just pwned irl Long time no see http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif

mortoma
10-06-2007, 08:57 AM
I find it strange that the author of this thread obtained different results than I achieved under the same circumstances. But I used a full tank of fuel instead of half like he did!! I flew it on the Okinawa map, so it was possibly a different map with different temperature profile. But being a tropical map I should have flown slower than most temperate maps, as the temps are hotter and the speed should be slower. The author stated IAS, not TAS so I just used the speed bar for my speed report.

I maintained 1,500 feet at all times and was able to get 270mph/240knots. I had all the same weapons loaded, 10 HVARS and two 1,000 pound bombs. I also flew at exactly 90% throttle and 100% prop pitch.

ElAurens
10-06-2007, 11:24 AM
Dkoor, I am not trolling thank you.

These are the results that two of us achieved, flying wing on that map.

I am merely looking for an explanation, and so far all I get is the old "learn how to fly n00b" response. Hence the appelation "UBO Zoo".

joeap
10-06-2007, 11:29 AM
I thought you got the explanation ElAurens? Drag ought to explain it...from the ordinance and the auto rads. Anyway others have gotten different results so I don't know what to say. http://forums.ubi.com/images/smilies/35.gif

fordfan25
10-06-2007, 10:11 PM
yea something was way off for you. normaly at those settings ect i can easy maintain 270mph to 290 mph about 320mph full out