Horton

[Crumpp]

Milo says:
Only nine days after the specification was issued by the RLM (July 24, 1944), the first Me P.1101 had taken shape on paper.

Don't confuse the date Mtt got the contract from the RLM to start the prototype with the date the design was started.

The concept was completed long before the RLM issued their specification and awarded the money to Mtt to build it.

Dr Voigt tested the patent in a wind tunnel and in July 1942, Voigt and his team started designing such an aircraft,known as Project P 1101, backed by Messerschmitt.

the work on the P 1101 proceeded very slowly, until 1944, when the Oberkommando der Luftwaffe issued a requirement for a single-seat, single engine, turbojet fighter with a higher speed than the Me 262. Messerschmitt entered the P 1101 design and got the contract.

Milo posted:
Me262 pg 66 Smith/Creek

Really?

I would have to see the documents they refer too.

J. Richard Smith is undisputedly one of the world's foremost authorities on the history of the Luftwaffe. His works include the landmark publication Jet Planes of the Third Reich as well as Arado 234 Blitz, Luftwaffe Camouflage & Markings 1935-45, Me262, and numerous other leading aviation titles.

A qualified architect, Eddie J. Creek has for many years worked in partnership with Richard Smith producing a wealth of the most historically accurate line drawings and color artwork so far published on aviation in the Third Reich. As a historian and enthusiast, he has been actively collecting documents and photographs relative to the history of the Luftwaffe for over 30 years.

Niether one are engineers and most of the Luftwaffe was not either. Many times I have come across Luftwaffe documents with an erroneous explaination for engineering decisions.

The use of MW-50 in the BMW801 is filled with this to include memo's being issued to use a system the RLM technical office has to retract and clarify.

The fact remains that Mtt was heavilly involved by July 1942 in swept wing research and had gained experience flying swept wing designs.

It is a fact that in order to increase longitudinal control when mach tuck is encounted, you can move the forward CG to regain control power.

Swept wing research had been going on 8 years in Germany by the time July 1942 rolled around. In 1940, the LFA was sharing their research with industry leaders, including Mtt.

Since 1936 Busemann continued his scientific work at LFA on high speed aerodynamics and gasdynamics, and the beneficial effects of wingsweep on stability and control, and since 1937 he was in close contact about this subject with A. Betz of the AVA in Goettingen yielding a common
patent on the idea of sweepback for reducing drag and improving flight control issues at high subsonic speeds. In 1938 he again advocated the potential of wing sweep in order to maintain at least partially the favorable aerodynamic and flight mechanic properties of wings at lower speeds [16]. Since 1940 Busemann was visited by leading industrial aerodynamicists at LFA who picked up the idea of sweepback and initialized more wind tunnel data
bases at AVA, LFA and DVL.

In fact, Mtt developed the concept, applied for, and recieved the patent for a variable geometry swept wing in 1941.

Lippisch’s conception of both the variable sweep wing (Fig. 13, 14) for which Messerschmitt was granted a (then secret) patent in 1941. This led to the design of the Messerschmitt P.1101

Germans did not fully understand swept wing theory..

Mtt certainly understood the benefits enough during the design testing of the Me-262 to both modify the existing aircraft to add 18 degrees of sweep to increase the transonic flight envelope and to complete redesign the aircraft for later variants by adding 45 degrees of sweep.

Fact is they changed the wing from a straight wing to swept. I suspect they initially kept the center section straight to avoid the stability and control issues of a swept wing with nacelles.

It is simply not factual to argue that Mtt was unaware of the benefits of a swept wing and only "accidentaly" added wing sweep.

[ACE-OF-ACES]

Originally Posted by Crumpp

It is simply not factual to argue that Mtt was unaware of the benefits of a swept wing

Ah I see where you are confused..

As far as I know, nobody in this thread has stated the Germans knew nothing about swept wing theory..

About the only thing that was pointed out on that subject is the Germans did not fully understand swept wing theory..

As you your self admitted when you said

Originally Posted by Crumpp

Nobody fully understood swept wing theory until after the war.

As for the rest...

Originally Posted by Crumpp

and only "accidentaly" added wing sweep.

Ah I see where you are confused..

As far as I know, nobody in this thread is saying the wings were swept by accident..

All I am saying is the 'reason' the inner wing was swept to correct the cg, and 'reason' the outer wing was swept to correct the air separation..

And me saying this is not my opinion, I am simply repeating what the Me262 experts said, i.e.

Originally Posted by STORMBIRDS

it is true (as some writers seem intent on repeating loudly and often) that the Me 262s swept wing design was due to the need to adjust the center of gravity for the aircraft

Originally Posted by Dennis R Jenkins

The third prototype was the first Me 262 to fly on jet power alone, taking off on 18 July 1942 with two pre-production Jumo 004A-0 engines. The 12-minute flight reached an altitude of just over 6,000 feet and a speed of 375 mph. A second flight later the same day lasted 13 minutes and reached 11,000 feet and 450 mph. One problem that was immediately evident was that, in a bank, the airflow broke away early from the wing center section. A small fillet was added between the fuselage and engine nacelle, increasing the root chord and continuing the leading-edge sweep angle of the outer panels across the entire center section. This completed the change necessary to give the appearance of a truly swept wing.

Hope this helps!

S!

[Crumpp]

All I am saying is the 'reason' the inner wing was swept to correct the cg,

No the reason the inner wing was not swept is due to stability and control issues with engine nacelles. Tractor propellers and jet intakes forward of the CG exhibit a destabilizing force at high coefficients of lift. In a turn, the destabilizing force in wing mounted nacelles is not symetrical.

Adding sweep lowers and flattens the CLmax but extends the available angle of attack so that the wing achieves more angle for a lower coefficient. In otherwords, it increases the destabilizing force of the nacelles.

Mtt did not sweep the inner wing to reduce this effect. In the second design, they did not add sweep only because they understood the basic's of swept wing theory. Unlike anybody in the mainstream aircraft designers of United States or Great Britain at the time.

After flight testing though, the original high aspect ratio wing design CG limits were not suitable for the higher mach limits the outboard sweep allowed.

As an aircraft enters transonic flight, the progression of the normal shock moves the AC rearward reducing the elevators effectiveness.
Additionally, the downwash angle behind the wing is decreased due to the seperated flow behind the normal shock. This increases the angle of attack of the horizontal stabilizer which is the main cause of mach tuck.

An airplane originally designed to have a straight wing would need to expand the forward CG limits if you are to increase the elevators effectiveness if you are going to fly in the transonic realm.

and 'reason' the outer wing was swept to correct the air separation..

Well duh....

What do you think raising critical mach number is all about?? That is the whole point of adding sweep!!

Behind the normal shock is seperated flow. If we increase the critical mach, we reduce the amount of seperated flow on the wing.

[ACE-OF-ACES]

Originally Posted by Crumpp

No the reason <snip>

Now don't take this personal!

But I am going to stick with the Me262 experts (Jenkins and STORMBIRDS) on this one..

Who said..

• The 'reason' the outer wings were swept was to correct the cg.

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

It is nothing personal!

It is just when you consider the fact that Dennis Jenkins has written more aviation books than most people have read, and that the folks at STORMBIRDS surly reviewed all the research on the Me262 during the process of building reproductions of the Me262.

It would be silly to pick you over them!

But I still want to thank you for sharing your personal beliefs and opinions!

But to be honest, I really don't care about what you personally belive and your opinions!

All I care about is what can be proven.

I mean if we don't draw the line there was is to stop someone from posting in this thread that they 'belive' and are of the 'opinion' that the Germans were assisted by aliens from outer space?

So with that said I think you can understand why I drawn the line there..

I also want to thank you for information and calculations you provided!

But I am sure the likes of Dennis Jenkins and STORMBIRDS are privy to that same information/calculations and MORE and took it all into account during their research of the Me262 and their ultimate statements on the reason why the wings were swept.

Which begs the question as to why they didn't come to the same conclusions you did?

I suspect they wanted to..

In that the whole history channel 'the Germans were supermen' stuff sells these days..

Especially the folks at STORMBIRDS who are pro German tech biased..

But I suspect the stopped short of making the claims you made because they just could not find any real proof of the connections your claiming are there. That and unlike you they have a reputation to consider! I mean think about it, nothing would hurt their image, and thus sales, more than for them to say something they said was based on proof only to find out later there was no proof!

So with that said..

We will just have to agree to disagree as to the reasons why the wings were swept on the Me262

S!

[Al Schlageter]

Originally Posted by Crumpp

Don't confuse the date Mtt got the contract from the RLM to start the prototype with the date the design was started.

The concept was completed long before the RLM issued their specification and awarded the money to Mtt to build it.

Sure it was,

Design and development

Within nine days of the 15 July 1944 issuance of the design specifications for the Emergency Fighter, the Messerschmitt design bureau under Woldemar Voigt had formed a preliminary paper design for the P.1101. The aircraft which was developed initially had a short and wide fuselage, tricycle landing gear, and mid-mounted wings with an inner sweep of 40 degrees near the fuselage, and a shallower 26 degree angle outboard. The single He S 011 jet engine was to be mounted internally within the fuselage, being aspirated by two rounded intakes located on either side of the cockpit. The tail was of a V configuration, and mounted on a tapered boom which extended over and past the jet exhaust, while the cockpit was forward mounted, with the canopy integrated into the fuselage and forming part of the rounded nose of the aircraft.

By late August 1944, the design still in paper form had evolved into a sleeker incarnation, with the previously stout fuselage lengthened and narrowed with a conical nose section added in front of the cockpit. The double angled wing was also abandoned, with the outer wing of the Me 262 instead being adapted for the design. The design was further developed, and after the wind tunnel testing of a number of wing and fuselage profiles, the design was further modified and finalized, with the decision made to undertake the construction of a full-scale test aircraft. This finalized design and associated test data were submitted to the Construction Bureau on 10 November 1944 and the selection of production materials was begun on 4 December 1944.

On 28 February 1945, the RLM settled on a competing design, the Focke Wulf Ta 183, as the winner of the Emergency Fighter program. This decision was based in part on the considerable design difficulties being encountered by the Messerschmitt P.1101 design team. For example, the cannon installation was proving too crowded, the mainwheel retraction and door mechanisms were too complex, the fuselage needed a great number of “strong points” to deal with loads, and the anticipated performance had fallen below the RLM specifications due to increased weight.

The airframe, considered of no intelligence value after an interview with Voigt revealed its many design flaws, was put on outdoor display and became a favorite prop for GI souvenir photos.

As fro Smith/Creek, despite writing a 900 page tome on the Me262, they just pulled the CG and swept wing out of thin air.

Even as late as July 18 1943, the Me262 V3 didn't have the sweep to the inner leading edge of the wing. The results of the tests in the Gottingen high speed wind tunnel were treated with great caution by the company's project office.

[Crumpp]

you made because they just could not find any real proof of the connections your claiming

Thank you for the laughs!! I guess you don't understand the fact your sources are not wrong at all. They only convey a portion of the story but their facts are correct.


The information I posted comes from:

AIAA is the world’s largest professional society devoted to the progress of engineering and science in aviation, space, and defense.

Today, with more than 35,000 members, AIAA is the world's largest professional society devoted to the progress of engineering and science in aviation, space, and defense. The Institute continues to be the principal voice, information resource, and publisher for aerospace engineers, scientists, managers, policymakers, students, and educators.

You do realize that in the decades since WWII, we in the United States have had time to sort through the data compliled by the Germans. We have a much better understanding of their work and swept wing theory.

That is why those papers were published and presented at conferences for engineers and scientist.

In 1946 when the NACA and USAAF references your "experts" use were written, the United States had little to know understanding of swept wing theory.

Notice the P-80 had straight wings.....


Yes, the outer wings were swept to eliminate flow seperation!!

What do you think raising critical mach number is all about?? That is the whole point of adding sweep!!

Behind the normal shock is seperated flow. If we increase the critical mach, we reduce the amount of seperated flow on the wing.

Yes, the aircraft benefited from just 18 degrees of wing sweep!!!

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.

Yes the center portion was adjusted to expand the forward CG limits!!!

In the transonic region, the formation of shock waves on the wing surface and the resulting separated flow (Figure 7.1) causes movement of the wing aerodynamic center.

The aft shift of the aerodynamic center is analogous to moving the airplane center-of-gravity forward.

http://www.google.com/url?sa=t&rct=j...kmfr_LD2mjThuA

After flight testing though, the original high aspect ratio wing design CG limits were not suitable for the higher mach limits the outboard sweep allowed.

As an aircraft enters transonic flight, the progression of the normal shock moves the AC rearward reducing the elevators effectiveness.
Additionally, the downwash angle behind the wing is decreased due to the seperated flow behind the normal shock. This increases the angle of attack of the horizontal stabilizer which is the main cause of mach tuck.

An airplane originally designed to have a straight wing would need to expand the forward CG limits if you are to increase the elevators effectiveness if you are going to fly in the transonic realm.

The sources you quote are correct and the sources they use were written at a time when you could count on one hand the number of United States Aereonautical Engineers who knew anything at all about swept wing theory.

Who said..

The 'reason' the outer wings were swept was to correct the cg.

yes it was...see above and it fits with swept wing theory.

The 'reason' the inner wings were swept was to correct the airflow separation.

yes it was...see above and it fits with swept wing theory.

[ACE-OF-ACES]

Originally Posted by Crumpp

They only convey a portion of the story

Well that is your opinion and your welcome to it!

But I am going to stick with the Me262 experts (Jenkins and STORMBIRDS) on this one..

Who said..

• The 'reason' the outer wings were swept was to correct the cg.

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

It is nothing personal!

It is just when you consider the fact that Dennis Jenkins has written more aviation books than most people have read, and that the folks at STORMBIRDS surly reviewed all the data on the Me262 during the process of building reproductions of the Me262.

It would be silly to pick you over them!

But I still want to thank you for sharing your personal beliefs and opinions!

But to be honest, I really don't care about what you personally belive and your opinions!

All I care about is what can be proven.

I mean if we don't draw the line there was is to stop someone from posting in this thread that they 'belive' and are of the 'opinion' that the Germans were assisted by aliens from outer space?

So with that said I think you can understand why I drawn the line there..

I also want to thank you for information and calculations you provided!

But I am sure the likes of Dennis Jenkins and STORMBIRDS are privy to that same information/calculations and MORE and took it all into account during their research of the Me262 and their ultimate statements on the reason why the wings were swept.

Which begs the question as to why they didn't come to the same conclusions you did?

I suspect they wanted to..

In that the whole history channel 'the Germans were supermen' stuff sells these days..

Especially the folks at STORMBIRDS who are pro German tech biased..

But I suspect the stopped short of making the claims you made because they just could not find any real proof of the connections your claiming are there.

That and unlike you they have a reputation to consider!

I mean think about it, nothing would hurt their image, and thus sales, more than for them to say something they said was based on proof only to find out later there was no proof!

So with that said..

We will just have to agree to disagree as to the reasons why the wings were swept on the Me262

S!

[Crumpp]

As fro Smith/Creek, despite writing a 900 page tome on the Me262, they just pulled the CG and swept wing out of thin air.

Right!!

Why the heck would anyone think they just did it out of thin air???

Of course they did not, the Germans had 7 years of swept wing theory research and development behind them. Not only that, Mtt was a leader in the German aviation industry with swept wing designs already in flight!!

It is silly to try and make the case they did not know or consider it when they added wing sweep to the Me-262!!

Tagart said..

The 'reason' the outer wings were swept was to correct the cg.

Crumpp says: yes it was...see above and it fits with swept wing theory.

The 'reason' the inner wings were swept was to correct the airflow separation.

Crumpp says: yes it was...see above and it fits with swept wing theory.

[ACE-OF-ACES]

Originally Posted by Al Schlageter

The results of the tests in the Gottingen high speed wind tunnel were treated with great caution by the company's project office.

And rightly so!

Swept wing theory was in it's infancy, and as with any new technology that translates into proceeding with caution.

I mean that is something we all seem to agree one, even Crummp said the following on the topic

Originally Posted by Crumpp

Nobody fully understood swept wing theory until after the war.

So it is clear to everyone that this was new territory that could have gone either way.

[ACE-OF-ACES]

Originally Posted by Crumpp

Fixed that for ya!