Horton

[ACE-OF-ACES]

Originally Posted by Crumpp

I am confused on just what your opinion is now.

Agreed in that you are all over the place on this topic..

To sum it up

• The outer wings were swept to correct the cg.

• The inner wings were swept to correct the airflow separation.

And note..

Those are NOT my opinions!

I am simply agreeing with the folks at STORMBIRDS and Jenkins who said those two things

Hope that helps!

S!

[Crumpp]

I am simply agreeing with the folks at STORMBIRDS and Jenkins who said those two things

OK....

I guess Stormbirds never picked up a calculator and I am sure you are focusing on minutiae taking Jenkins out of context to fit your agenda.

In otherwords, if someone asked Jenkins if the ME-262 benefited from 18 degrees of sweep angle, he would pick up a calculator and say:

Our critical Mach number is raised by reciprocal of the cosine of the angle of sweep. So for 18 degrees of sweep we see a 1.05146 increase to critical mach.

So mach limit of Mach .8 becomes a new limit of .84.

Now at sea level that is represents a 30mph increase in speed!

Now the drag reduction is proportional to cos^2<angle of sweep>

Or a 9.5% reduction in drag.....

Not a bad call on the part of Mtt to add 18 degrees sweep based off their advanced knowledge of swept wing theory. By keeping the sweep moderate, they certainly avoided all the stability and control issues found with sweep angles and engine nacelles.

What is your opinion based on again?

[bongodriver]

Amateurs...they should have gone for 19 degrees.

[ACE-OF-ACES]

Originally Posted by Crumpp

OK....

I guess Stormbirds never picked up a calculator and I am sure you are focusing on minutiae taking Jenkins out of context to fit your agenda.

In otherwords, if someone asked Jenkins if the ME-262 benefited from 18 degrees of sweep angle, he would pick up a calculator and say:

Our critical Mach number is raised by reciprocal of the cosine of the angle of sweep. So for 18 degrees of sweep we see a 1.05146 increase to critical mach.

So mach limit of Mach .8 becomes a new limit of .84.

Now at sea level that is represents a 30mph increase in speed!

Now the drag reduction is proportional to cos^2<angle of sweep>

Or a 9.5% reduction in drag.....

Not a bad call on the part of Mtt to add 18 degrees sweep based off their advanced knowledge of swept wing theory. By keeping the sweep moderate, they certainly avoided all the stability and control issues found with sweep angles and engine nacelles.

If I didn't know better..

I would get the impression that your claiming to know more about the Me262 development than the folks over at STORMBIRDS and Jenkins..

If so, than that is another thing we will have to agree to disagree on!

S!

[bongodriver]

I would get the impression that your claiming to know more about the Me262 development than the folks over at STORMBIRDS and Jenkins..

Now why would anyone get that impression of him?

[ACE-OF-ACES]

Originally Posted by bongodriver

Now why would anyone get that impression of him?

Well the odd things is that most if not all admit that the 18.5 degree sweep was too slight to achieve any real significant advantage in the mach number..

Even those who don't agree on the reason for the wing sweep admit that..

So he is really in the minority with this line of reasoning..

As for his claim that I am focusing on minutiae an taking Jenkins out of context to fit my agenda

Here is what Jenkins had to say about 18.5 degree sweep angle and associated mach number (in red)

Originally Posted by Jenkins

After the war, "Watson's Whizzers," led by Colonel Harold E. Watson from USAAF Air Technical Intelligence, shipped several intact Me 262s to the United States for further evaluation. The tests, conducted by Albert Boyd (the head of flight test for the USAAF) and a soon-to-be-legendary Chuck Yeager, determined that the performance of the Me 262 was essentially equal to the P-80A. The Me 262 had a slightly higher critical Mach number-0.83 Mach versus the handbook limit of 0.80 Mach for the P-80A--but the difference was of little value in the real world since the Me 262 could only reach that velocity in a dive, whereas the P-80A could do it in level flight. However, despite the fact that the Me 262 was almost 2,000 pounds heavier than the P-80A, the German aircraft accelerated quicker and had approximately the same climb performance. During the tests it was found that the slightly swept wing of the Me 262 provided no useful reduction in drag, mainly because the triangular cross-section of the fuselage created so much base drag that nothing could really help much. The swept wing did not change the critical Mach number by a measurable amount, and certainly did not help performance in the low transonic region where the Me 262 was particularly unstable. The P-80A had much better handling characteristics than the Me 262, largely because it was more refined aerodynamically and had its thrust vector on the centerline of the aircraft instead of at the quarter-span of each wing.

As you can see Jenkin's comment consist of both pros and cons, and his comment wrt mach benefits of the Me262 18.5 degree wing sweep agree with the majority.

So as you can see from Jenkins comments, nothing was taken out of context on my part, no agenda on my part, no opinion on my part

All I am doing is agreeing with Jenkins comments!

[Al Schlageter]

I see this thread is going downhill fast and will soon be locked.

Why is it when a certain person shows up the thread goes downhill and is locked?

[Crumpp]

Jenkins had to say about 18.5 degree sweep angle

No, Jenkins paraphrases the results of flight test results of captured airframes

After the war, "Watson's Whizzers," led by Colonel Harold E. Watson from USAAF Air Technical Intelligence, shipped several intact Me 262s to the United States for further evaluation. The tests, conducted by Albert Boyd (the head of flight test for the USAAF) and a soon-to-be-legendary Chuck Yeager, determined that the performance of the Me 262 was essentially equal to the P-80A. The Me 262 had a slightly higher critical Mach number-0.83 Mach versus the handbook limit of 0.80 Mach for the P-80A--but the difference was of little value in the real world since the Me 262 could only reach that velocity in a dive, whereas the P-80A could do it in level flight. However, despite the fact that the Me 262 was almost 2,000 pounds heavier than the P-80A, the German aircraft accelerated quicker and had approximately the same climb performance. During the tests it was found that the slightly swept wing of the Me 262 provided no useful reduction in drag, mainly because the triangular cross-section of the fuselage created so much base drag that nothing could really help much. The swept wing did not change the critical Mach number by a measurable amount, and certainly did not help performance in the low transonic region where the Me 262 was particularly unstable. The P-80A had much better handling characteristics than the Me 262, largely because it was more refined aerodynamically and had its thrust vector on the centerline of the aircraft instead of at the quarter-span of each wing.

During the tests it was found that the slightly swept wing of the Me 262 provided no useful

<sarcasm on>

Of course this was at the height of allied knowledge and design savvy on swept wing theory.

<sarcasm off>

I wonder what the test teams basis for calculating the gains from the wing sweep where when the formulation for estimating it was not in their possesion??

How could they make any estimation at all of the performance impact of wing sweep???



Oh yeah, the couldn't.......but it was nice to hear their opinion in the report.

[ACE-OF-ACES]

Originally Posted by Crumpp

No, Jenkins paraphrases the results of flight test results of captured airframes

You need to read a little bit further past the part you put in bold to see where hecomments on the benefits of the 18.5 degree wing sweep

Allow me..

During the tests it was found that the slightly swept wing of the Me 262 provided no useful reduction in drag, mainly because the triangular cross-section of the fuselage created so much base drag that nothing could really help much. The swept wing did not change the critical Mach number by a measurable amount, and certainly did not help performance in the low transonic region where the Me 262 was particularly unstable. The P-80A had much better handling characteristics than the Me 262, largely because it was more refined aerodynamically and had its thrust vector on the centerline of the aircraft instead of at the quarter-span of each wing.

And as noted, Jenkins is not the only one to say that..

Most if not all agree the 18.5 was too slight to achieve any real significant advantage in the mach number..

Hope that helps!

S!

[Crumpp]

The Me 262 had a slightly higher critical Mach number-0.83 Mach versus the handbook limit of 0.80