Bf-109K

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yikes. LoL. After reading posts like this along with others, it didn't suprise me that gentlemen like the one who authored the post i was using as an example chooses to hang out on a gaming website vs. a dedicated aviation forum on which to "educate" us with the facts

Unfortunately, I must include myself in the "aviation for dummies" catagory at least when it comes to breaking down the science of flight itself. Can you walk me through the above a little more in terms of definition of terms/abreviations and how the formulas are used?



How would you factor in roll rate at x altitude and y speed and rate of turn?


SWAG?
 
How would you factor in roll rate at x altitude and y speed and rate of turn?

What is the importance of roll rate or how do I calculate it?

Calculating it is far beyond the scope of this thread. I can give you some very rough ballpark techniques is all.

t factor, p, and several other characteristics are generally derived from test data.

Lateral dynamics are extremely complicated.

Roll rate represents a designs agility or ability to change the orientation of the vector of lift.

SWAG - Scientific Wild Azz Guess

All the best,

Crumpp
 
Can you walk me through the above a little more in terms of definition of terms/abreviations and how the formulas are used?

SMOE - Standard means of evaluation - Term used to descibe 1/SQRT sigma. Sigma is the density ratio which equals pressure/pressure at sea level on a standard day. Pressure units are in slugs/ft^3

To convert velocity in EAS to TAS we have to account for density effects of the atmosphere.

Here is a primer on airspeed:

Airspeed - Wikipedia, the free encyclopedia

All the best,

Crumpp
 


I'm not sure that this is fair to say with that info that 109 is faster, because in the above calculations P-47 is 6500ft (2km) higher, so when it would be lower on the same alt as 109 it of course would have smaller max TAS but that still could be more than 440mph for example 441mph. I'm not saying that P-47 is faster, I just think it's not enough info to say that 109 is faster.
 
Marshall,

Equivilent Airspeed removes the effects of altitude you understand that right? That is why engineer's use EAS to compare performance and not TAS.

so when it would be lower on the same alt as 109

Altitude effects are removed so the aircraft ARE essentially at the same altitude or at least in a comparible condition of flight.

Understand?

All the best,

Crumpp
 
Range at most economical cruise. Not a good idea in a airspace dominated by the USAAF if one wants to live to old age.

P-47D-25-RE: range ~1500 miles. Range with maximum external fuel was 1800 miles

I am confused as to the point you where trying to make. Is Kurfurst somehow being deceitful for listing the range of the aircraft or are you simply pointing out that the range occurred at L/Dmax like every other airplane?

Was the P47 somehow more advantaged when flying at Best Range cruise velocity?

All the best,

Crumpp
 


Yes now I understand, my bad but from where do you take the numbers that you divied TAS with them?
 

No claims are made as to the validity of the data. I was just pointing out that unless you know what your doing, these comparison threads are really silly.

When you do know what you're doing, they become even sillier. All aircraft performance is a percentage range over a mean average. The performance any aircraft exhibits as "normal" can have a very wide swath.

IMHO, the middle of the envelope is the most interesting. The Prmin point, L/Dmax, and Cl^3/2/Cd are where we really find some unique differences in some of our WWII designs. That and the stability and control issues as it was a very new science at the time.

All the best,

Crumpp
 
I am confused as to the point you where trying to make. Is Kurfurst somehow being deceitful for listing the range of the aircraft or are you simply pointing out that the range occurred at L/Dmax like every other airplane?
I don't think it is that hard to understand what was said.

A 1000 miles might be good for a delivery flight to the EF where there was no chance of being bounced but once there the typical combat radius was ~140 miles.

I wouldn't say he was being deceitful but more like being dishonest as he failed to say if the range was clean, with drop tank, or with drop tanks.
 
A 1000 miles might be good for a delivery flight to the EF where there was no chance of being bounced

You understand that the same goes for the P47 or any other aircraft right?

The difference between Min Specific fuel consumption and Take Off power being 60 gallons per hour and 275 gallons per hour respectively for the P47.

All aircraft had to watch their fuel. The USAAF more so than the Luftwaffe when over Germany.

So these cruising Bf-109's are going be bounced by cruising P47's.

All the best,

Crumpp
 
IMHO P-47 versions that were used same time in Europe than 109K were late Ds and Ms. The latter was used by the last remaining 8th AF P-47 group, 56FG in 1945.
Performance of the P-47M-1-RE included a maximum speed of 400 mph at 10,000 feet, 453 mph at at 25,000 feet, and 470 mph at 30,000 feet. Initial climb rate was 3500 feet per minute at 5000 feet and 2650 feet per minute at 20,000 feet.
In fact it seems that actual test gave the rate of climb for P-47M as at S/L 3960 ft/min, 3740 ft/min at 10000ft and 3300 ft/min at 20000ft.

Juha
 
Performance of the P-47M-1-RE included

AFAIK the first P-47M's arrived in Europe on 04 Mar 1945 but were grounded due to engine difficulties digesting their special fuel until April 1945, just days before the war ended.

You could say the P-47M is a contemprary of the Ta-152H series and FW-190D13 series more so than the Bf-109K series. IIRC, the Bf-109K4 was operational much earlier in the war than the P47M.

All the best,

Crumpp
 
Where did you get that mis information?

The first P-47M was delivered from the factory in December 1944 with the 56FG getting their first on Jan 3 1945.. On Jan 14 1945 Paul Gonger made a claim of a 109.

There was problems with the high tension leads cracking (P-47Cs had a similar problem). There was some other problems like defective carb diaphrams, cylinder corrosion and over cooling but fuel was certainly not one of the problems.

On Feb 3 1945 a mission was flown to Berlin.

Yes they were grounded but all the FSs of the 56FG were flying P-47Ms by mid March 1945.
 
Where did you get that mis information?


No misinformation is posted. As I understand the documentation, they arrived at the group for operational testing then but were not posted to operational status until 04 Mar 45. Only half the squadron aborted with mechanical difficulties on their first mission in January. The other half flew the mission for the operational trials. Assesments were still needed of types usefulness in combat.

If you want to say that the type was operational from Jan 45 you are free to do so. IMHO, it would be like claiming the FW-190D9 was operational in October 1944. That would not be true however as the type was undergoing operational trials, the last phase of the testing regime to asses its worth as a combat aircraft before acceptance by the gaining service.

The type maintained this dismal relability rate throughout the trials until Pratt and Whitney got involved. Unfortunately Pratt and Whitney's solution turn out not to be the answer and it appears the type was prematurely posted to operational status.

The 50% abort rate the operational trials averaged was never fixed so that when on the very first mission in operational status, it led to the type being grounded until April 1945 so that relability could be increased to an acceptable level for a USAAF Operational Squadron.

Once again, the P47M was not a contemporary of the Bf-109K but belongs alongside the Ta-152H series, FW-190D13 series, and other late war aircraft that were not developed designs by wars end.

That is my opinion. You are entitled to paint the aircraft as fully developed and a viable operational aircraft if you like.

All the best,

Crumpp
 
Hello Crumpp
based on secondary sources only I tended to side Al here. It seems that 47M was grounded twice, a couple days in late Feb and from 16th to 24th March 45. Time to 31th March was troublesome but by leafing through McLaren's Beware the Thunderbolt! abort rate wasn't anywhere near 50% during first half of March. And 56th flew ops almost daily. Usually understreght, maybe 50% included also those not even booked for mission?

Juha
 
 

Well, for what it's worth, this website author would appear to agree with Crump's assertation regarding the hotrod versions of the P-47


The Republic P-47 Thunderbolt

If the above has a fair degree of accuracy, I'd say it's probably more fair to rate the worked up P-47M/N series against the TA-152H which was Germany's next generation answer to the high alt fighter. The 109K varient I still consider somewhat of an interim fix using an aging airframe passing into obsolecense. They did a decent job considering but ultimately it was falling behind the curve of the newer airframes like the 47.
 
What is the importance of roll rate or how do I calculate it?

Actually I was referring to the straight up comparisons that usually occur in these "comparison type" threads. In this case (P-47 vs Me-109) at high altitude it was asserted that the Thunderbolt could "outroll" and "out-turn" the Me-109.

As mentioned, I've read that the Thunderbolt was suprisingly agile and nimble for such a huge fighter in the thin air @ 30+K. But i'm wonder how much more agile it really is. I understand you to say that two planes turning in the same way are identical. The assertation is that one plane can turn/roll more sharply than the other at x speed.


SWAG - Scientific Wild Azz Guess

All the best,

Crumpp

LoL. Thought that was what you meant.
 

Wow....my head is spinning. How did you get the numbers?



Thx for the link. Started looking at it, but admitedly all the math is confusing the hell out of me. I'm still not sure I understand why EAS is more accurate than TAS unless its because the TAS indicator is misleading the pilot because thats what his instrument states but his actual airspeed is calculated via the EAS formula.......

Almost makes me long for the days of Zero vs Wildcat. aieee.
 
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