Author Topic: New 109's (Read 3042 times)

Crumpp · « **Reply #60 on:** October 13, 2005, 02:12:36 PM »

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TK 589 was 2 mph faster than your beloved 1.98 ata K-4's 'good production' estimated sea level speed of 377 mph.

Does anybody else see the humor in arguing over 2 mph?

Why does every thread in this forum degenerate into "my plane is better than your plane"?

Everyone here does know that manufacturers had tolerances specifications. They would only guaranteed performance within a percentage variation. 1 percent variation was considered good and well within tolerance. 2 mph is barely a 1/2 a percentage point from 377mph. Those tolerances were pretty broad even at 1 percent. The FW190 had a 15kph margin between the best and worst tested data. All was within the 1 % manufacturers guaranteed performance.

Can we get this back on track instead of watching the same old tired players acting on the stage again pushing private agendas?

All the best,

Crumpp

LRRP22 · « **Reply #61 on:** October 13, 2005, 02:35:50 PM »

Oh, so now 8 mph at seal level has become 12 mph, huh?

368 - 8 = 360. That's 4 mph slower than 43-24777's SL speed.

Then again, AHT says the USAAF reached 373 at SL.

373 - 8 = 365. That's 1 mph faster than 43-24777's SL speed with racks.

Despite what you like to claim, NAA and the USAAF rated the P-51D within 1-2 mph of the P-51B-15-NA at all altitudes, i.e. 439 mph vs 437 mph. Of course, NA-46-130 rates the P-51D at 440 mph clean as opposed to the 437 mph usually listed. You left that out, though.

Like I've told you repeatedly, I don't have a problem with TK 589's speeds. Just take them for what they are: speeds attained by a veteran example, not a factory fresh example. Still, even used, TK589 was faster was faster than the 1.98 ata K-4 at sea level on virtually identical power. Not bad for a veteran airframe vs calculated data, huh?

Again, lets see that 109K-4 Test data....

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Originally posted by Kurf�rst
BTW it's interesting to compare the P-51D TK 589 flight data (with wingracks) with the 'official

Let's recall that TK 589 did 354mph at SL at 67", and removing the wing racks would give an extra 12mph :

North American Aviation, Inc.
Inglewood, California
Report No. NA-46-130
2-6-46
Performance Calculations for Model P-51D Airplane
(N.A.A. Model No. NA-122)

These calculations were prepared in connection with a comparison of the P-51D and P-51H airplane. Considerable effort was expended to achieve agreement between flight tests and calculated results, and the data as presented represent good agreement with most of the flight test results.

Calculated Altitude Performance
Fighter condition - No external load
67" HG M.P. - 3000 R.P.M.
9,611 LB
Maximum Speed

Standard Altitude Feet True Airspeed - M.P.H.
Sea Level 368

368 - 12 = 356...

TK 589 did 354mph....

LRRP22 · « **Reply #62 on:** October 13, 2005, 02:38:31 PM »

It's not about 2 mph, Crumpp. It's about Isegrim constantly making spurious comparisons and misrepresentations. I know you've butted heads with him repeatedly over the very same issues...

Quote

Originally posted by Crumpp
Does anybody else see the humor in arguing over 2 mph?

Why does every thread in this forum degenerate into "my plane is better than your plane"?

Everyone here does know that manufacturers had tolerances specifications. They would only guaranteed performance within a percentage variation. 1 percent variation was considered good and well within tolerance. 2 mph is barely a 1/2 a percentage point from 377mph. Those tolerances were pretty broad even at 1 percent. The FW190 had a 15kph margin between the best and worst tested data. All was within the 1 % manufacturers guaranteed performance.

Can we get this back on track instead of watching the same old tired players acting on the stage again pushing private agendas?

All the best,

Crumpp

MiloMorai · « **Reply #63 on:** October 13, 2005, 02:44:42 PM »

See Rule #4

Kurfürst · « **Reply #64 on:** October 13, 2005, 02:44:43 PM »

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Originally posted by Crumpp
Why does every thread in this forum degenerate into "my plane is better than your plane"?

Ask Larpy.

Quote

Everyone here does know that manufacturers had tolerances specifications. They would only guaranteed performance within a percentage variation. 1 percent variation was considered good and well within tolerance. 2 mph is barely a 1/2 a percentage point from 377mph. Those tolerances were pretty broad even at 1 percent. The FW190 had a 15kph margin between the best and worst tested data. All was within the 1 % manufacturers guaranteed performance.[/B]

Indeed. From what I have seen, manufacturers would guarantee a speed performance within 3% of the nominal figures, ie. those planes 3% below official top speed were accepted, too... now if one thinks it over, that mean an 'officially' 400mph plane was accepted even if it could do only 388mph... and if you think it over again, did that 10 mph differece in top level speed reached after 2-3 minutes in straight and level flight made real difference in air combat?

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Can we get this back on track instead of watching the same old tired players acting on the stage again pushing private agendas?[/B]

Just take note that I merely shared my data with others when I posted the speed loss for the 109 gondolas in a 109 thread. I really fail to see what's the problem with that... I really can't understand reactions like that : after seeing some specs for 109 gondolas, to start screaming BUT MY MUSTANGS BOMB RACKS WERE LESS DRAGGY!!!!

So don't count me in your plural, would you?

Kurfürst · « **Reply #65 on:** October 13, 2005, 02:46:34 PM »

See Rule #4

butch2k · « **Reply #66 on:** October 13, 2005, 02:49:30 PM »

According to German doc MG 151 Gondolas increased Cw by 0.001

LRRP22 · « **Reply #67 on:** October 13, 2005, 02:50:10 PM »

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Originally posted by Kurf�rst
BUT MY MUSTANGS BOMB RACKS WERE LESS DRAGGY!!!!

[/B]

They were.

.

MiloMorai · « **Reply #68 on:** October 13, 2005, 02:58:39 PM »

See Rule #4

Debonair · « **Reply #69 on:** October 13, 2005, 03:00:25 PM »

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Originally posted by Charge
Debonair, I would say that the way you described them especially in slow speed their effect is very small if it exists at all.

They do help the contemporary airliners to save fuel at their normal cruising speeds by reducing the wingtip vortices and their effect on drag.

-C+

I was taught that winglets are to reduce induced drag & wingtip vortices which are a phenomenon of low speed flight & worst in the condition of heavy, clean & slow. I've never heard ATC tell anyone in the flight levels "caution wake turbulence", but tower & approach/departure control give this warning regularly. If this is the case, then reduce drag is akin to increased performance, isn't it? Actually maybe not. Modern aerobatic planes dont have winglets. Honestly I dont know, which is why I asked for other's opinions. You gave yours & now I'm arguing with you so I guess I'm kind of a jerk...

Charge · « **Reply #70 on:** October 13, 2005, 06:05:16 PM »

I haven't heard that they work well at slow speed and that surprised me.
It's true that especially near airfields the effect of vortices can be disastrous but I don't know how much the winglets help to that problem other than keeping the descending vortice away from the top of the wing.

It doesn't make anybody a jerk if he's discussing matters in a civil manner.
Good question BTW and I'm afraid I don't know the exact answer but this is how I see it.

-C+

Angus · « **Reply #71 on:** October 13, 2005, 07:21:51 PM »

Oh come on, stop bashing each other with Rule #4 and so on

Anyway, when the discussion goes about 1% differences between PS and HP and 2 mph top speeds, - then IMHO somebody is grabbing a straw,- while at the same time nobody mentions weight difference of what, - 1000 - 2000 lbs maybe (?).
The paint is another issue. AFAIK the Germans were ahead in their finishing, so their paint weight is not a penalty. Crumpp has the numbers I belive, if I remember correctly, a good finish could make some 10 mph.

Crumpp · « **Reply #72 on:** October 13, 2005, 08:19:19 PM »

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Crumpp has the numbers I belive, if I remember correctly, a good finish could make some 10 mph.

That depends on the aircraft Angus.

Some aircraft were greatly affected by finish such as the Bf-109 and the P 51. Others like the FW190 were hardly affected at all. "Filled and Polished" adds 5kph or less on average to the FW190A.

All the best,

Crumpp

Krusty · « **Reply #73 on:** October 13, 2005, 08:25:25 PM »

But on a p51 it means a bit more (which is the example brought up). If they did speed tests on something where the guns were patched over, the camera hole, the shell ejection chutes, and the entire wing from the gear inwards (if I read that properly) was filled and POLISHED, I think that's a skewed non-standard result.

Had they wanted a good result they'd just have cleaned the thing and put it in the air as-is.

LRRP22 · « **Reply #74 on:** October 13, 2005, 08:56:40 PM »

Quote

Originally posted by Krusty
But on a p51 it means a bit more (which is the example brought up). If they did speed tests on something where the guns were patched over, the camera hole, the shell ejection chutes, and the entire wing from the gear inwards (if I read that properly) was filled and POLISHED, I think that's a skewed non-standard result.

Had they wanted a good result they'd just have cleaned the thing and put it in the air as-is.

Krusty,

All Mustangs' wings were primed and filled at the factory. It was in no way skewed. Quite the opposite in fact. I'll post a picture of TK589's starboard wing later- it was anything but 'Polished'. You'll see why I described it as "well used".

LRRP

EDIT: Here you go...

See what I mean by 'well used'?

.