Author Topic: 109 Flaps (Read 8992 times)

gripen · « **Reply #210 on:** February 05, 2006, 12:08:40 AM »

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Originally posted by niklas
gripen, you named naca reports etc. speaking in favour of the spitfire.
Why don´t you say that ALLl naca report mention a thickness ratio of 30-40% to be favorable for high speed flight?

I have not named here any NACA report (nor RAE report nor what so ever) in favour of the Spitfire. What I say above is that long term and large scale high speed research done by RAE (theoretical and experimental) support relatively low drag rise of the Spitfire at high mach numbers and low Cl values without cherry picking any particular report.

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Originally posted by niklas

The spitfire with 20% chord ratio, steep gradient right away from the edge (don´t forget it´s depth, the win is thicker than that one of a 109!).

It's relative thickness which matters, using same logic the Saab Draken would not have been been supersonic because it has much thicker wing than the Bf 109.

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Originally posted by niklas

Both features, steep gradient in the pressure gaining section and aprupt turn towards decreasing thickness is EXACTLY the opposite of ALL late, post war and current designs who have all a shallow gradient due to 30-40% chord placement, a more symmetric layout on upper and bottom side and especially (and this is first mentioned in german sources during the war) a flat middle seciton on the topside to allow a gentle recover from supersonic airflow.

What is the problem here? I say above that the Spitfire wing was absolutely not good for high mach numbers. But it does not change the fact that at low Cl, it had relatively low drag rise at high mach numbers.

gripen

Knegel · « **Reply #211 on:** February 05, 2006, 03:46:29 AM »

Hi Nashwan,

according to my airspeed calculator 430mph IAS are 602MPH in 20000ft.
The Spitdatas give 430mph IAS up to 25000ft , here my calculator say 645mph, oh thats mach1 in this altitude.

In 20.000ft mach1 already did decrease to only roundabout 1070km/h!!

So even with your IAS calculation, even 590mph would be still mach0,89 in 20000ft and even more fast in 25000ft!!

Still not very credible, eh??

"Where does the 606 mph at 20k figure come from? In the RAE chart I have, maximum speed was 606 mph at 28,820 ft. Speed at 20,000ft was down to 510 TAS, and the pullout was underway."

606mph in 28.000ft?? Thats around mach0.96 in this altitude!!!
Realy, who will believe this(i jknow some do)??
I realy wonder why they made long tests with the rocket powered planes, they should have used a Spitfire in combination with a rocket, they would have reached Mach1 by easy, if it already almost did reach it while a thrustless dive!!

No, thats not credible!

Greetings,

Crumpp · « **Reply #212 on:** February 05, 2006, 05:44:57 AM »

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I have not named here any NACA report (nor RAE report nor what so ever) in favour of the Spitfire. What I say above is that long term and large scale high speed research done by RAE (theoretical and experimental) support relatively low drag rise of the Spitfire at high mach numbers and low Cl values without cherry picking any particular report.

The Spitfire was not a low drag design. Anyone can get a polar and see.

Angus · « **Reply #213 on:** February 05, 2006, 05:51:33 AM »

A Spitty with a rocket, - or basiclly any other prop fighter, - in a dive, - would have hit mach 1 and probably disintegrated.
And of wing thickness: no wings at all are better

There is one thing about those high-speed dives, - the airflow around the control surfaces may have broken mach.....

But anyway, what is being claimed here has a funny angle.
If Mach 0.8 is the wall for the normal ww2 prop fighter, then the lot of them will end up diving at that speed. Not much to choose between. Some of them will compress, others not. So, a good diver is an aircraft that accelerates fast in the initial part.
If this 0.8 figure holds, then also claims of many a pilot as well as the RAE tests have to be wrong. Even some of the manuals have to be wrong.

Crumpp · « **Reply #214 on:** February 05, 2006, 06:01:37 AM »

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If Mach 0.8 is the wall for the normal ww2 prop fighter,

There are pretty much all around Mach ,8 Angus.

gripen · « **Reply #215 on:** February 05, 2006, 06:56:43 AM »

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Originally posted by Crumpp
The Spitfire was not a low drag design. Anyone can get a polar and see.

The question is about relatively low drag rise at high mach numbers and low Cl.

gripen

Angus · « **Reply #216 on:** February 05, 2006, 07:49:49 AM »

The 109 has 900 km/h as a limit, I belive in the manual. How much mach?
Yet there are pilots that claimed to have crossed it.
Yet the were caught with P47's.
Don't see 0.8 as an ultimate, that's all.

Crumpp · « **Reply #217 on:** February 05, 2006, 07:56:45 AM »

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The question is about relatively low drag rise at high mach numbers and low Cl.

No doubt, Gripen and I meant what I said. Examining a drag polar shows nothing remarkable or out of the ordinary in the Spitfire in comparision to other WWII fighters.

It's not hard to calculate either.

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How much mach?

.79 as stated or at least "as measured".

This is a really stupid argument as was posted by Guppy.

The Spitfire in quesiton was not even close to a production fighter and the propeller came off which is the biggest factor lending crediability to the measured speeds!

All the best,

Crumpp

Knegel · « **Reply #218 on:** February 05, 2006, 08:52:54 AM »

Hi,

900km/h TAS in low level are around mach0,73, even in 20000ft this 'only' would be mach0.84, but in this high alt the german planes wasnt allowed to dive that fast!!

But isnt the dive speed limit in the manual related to the speed the gauges show(IAS)?? In this case such values dont say anything regarding the real speed, cause the speed meter´s did vary pretty much.

Angus, you seems to forget that the measured speed with normal measurement systems (common pitot tube) get badly wrong at around mach0,75, even in normal speeds the measurement is pretty wrong with this system.
And for sure no WWII plane would have been able to reach mach1, they simply did miss the needed airfoil and toughness. They would have lost their wings due to shockwaves. As i wrote befor, even the Me163 and Me262 with their arrowed wings and thrust at highspeed wasnt able to reach Mach1. This planes even wasnt able to make a powered dive with more than 25° angle without to get into compressions, resulting in a endless dive. Mach 1 was far away.
The Me163 did reach 1006km/h(Mach0,84) in 3000m alt in level flight. But wasnt realy contollable anymore, it wasnt able to get much faster in a dive, its divelimit was .
Read here about the 163 and its highspeed problems, its critical mach was at "only" mach0,84!
http://mitglied.lycos.de/luftwaffe1/me163/me163_tactical.html

You realy think the Spit had a smaler drag than the Komet, with its smal wings and aspectratio?? The Komet was able to reach its critical mach of 0,84 while climbing, but yes, sure, the spit was able to reach a much faster speed. lol (read in the article about what happen when critical mach got reached)

btw, the aspectratio is a major factor for smal drag while highspeed flights, cause the air can get shifted away in a 2 dimensional way, much more important than the thickness of the wing. The Komet had a wing aspectratio of 4,85, the arrowed wing also got proven as advanced.

Greetings, Knegel

gripen · « **Reply #219 on:** February 05, 2006, 09:32:59 AM »

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Originally posted by Crumpp
No doubt, Gripen and I meant what I said. Examining a drag polar shows nothing remarkable or out of the ordinary in the Spitfire in comparision to other WWII fighters.

Hm... No one has argued otherwise here but regarding we are interested about drag rise on low Cl (dive condition) ie not about the shape of the polar.

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Originally posted by Crumpp

It's not hard to calculate either.

That would be interesting to see given your proven calculation skills so please show us.

gripen

Angus · « **Reply #220 on:** February 05, 2006, 10:41:06 AM »

Eh, Knegel:
"You realy think the Spit had a smaler drag than the Komet, with its smal wings and aspectratio?? "

Nope. Now, dive the Komet on full thrust, it will probably break the sound barrier very quickly and dissolve into a furball?

BTW, I have seen somewhere a text about the 262, where they speak of the control surfaces going supersonic. Well, it's the airflow that is supersonic, the hull isn't.

That Spit, at least dove fast enough to break the prop off. That tells you it's either faulty or reached a higher speed than other prop driven fighters.

BTW, browse up and look at the Hurricane pilot's experience. He goes fast enough to "redesign" the wings with the shockwaves. The shockwaves occur when?

Crumpp · « **Reply #221 on:** February 05, 2006, 11:27:08 AM »

You love to show that Gripen. How completely childish. Big Deal I made an error in calculation. It happens.

However Lets show the another portion of that thread:

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Lets compare the Spitfires with their contemprary FW-190 opponents:

Lets see and compare total drag @ 440fps at the Spitfires FTH altitude with the correct data:

BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps

BS354 - No data listed except the A/C was 7 mph slower w/50 bhp more output than the Merlin 66 @ (+18)

BS543 - 810.863789
FW-190A5 - 705.7484202

BS551 - 758.4823884
FW-190A5 - 704.890256

EN524 with 4 bladed prop - 765.4635575
FW-190A5 - 702.4712376

BS310 with 4-bladed prop - 793.0539968
FW-190A5 - 751.8834689

BS310 with 5 bladed prop - 794.0663191
FW-190A5 - 749.7161496

JL165 - done to death

MA 648 Merlin 66 (+18) SU Pump - 838.0549776
FW-190A5 - 804.8037275

BS310 - 792.6552588 Parasitic drag - 691.672177

FW-190A8 - 794.3964059 Parasitic drag - 606.4158622

At 315mph the total drag situation changes completely in the FW-190A8 favor.

JL165 vs FW-190A8 has been done to death, again in the FW-190A8's favor.

MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:

quote:
--------------------------------------------------------------------------------
External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake.
--------------------------------------------------------------------------------

MA648 - 837.1701001 parasitic drag - 751.6212076
FW-190A8 - 869.2121249 parasitic drag - 709.9624067

The parasitic drag is always in the FW-190's favor but the total drag drops to within a few pounds of each other at 315 Mph but never swings in the FW-190's favor.

So ONE example of the Spitfire Mk IX with an experimental air intake beats the FW-190A8 in total drag. The others are behind their FW-190A contemporary the whole way.

That about covers the Spitfire Mk IX's vs. their contemporary FW-190 adversary.

Crumpp

All the best,

Crumpp

Angus · « **Reply #222 on:** February 05, 2006, 11:31:08 AM »

Not being deep enough in my reading of "The principles of flight" I only remember that close to mach, the rules start bending. Well, maybe tomorrow, I'll, have somthing, that thing is about the size of the phonebook.
Anyway, Crumpp said this
"You love to show that Gripen. How completely childish. Big Deal I made an error in calculation. It happens"

Crumpp, we all make mistakes. This was not your only one, and by god, I am not innocent of them either. But I have never seen anyone so slick in defending his "slip" to the death as you.

Sorry.

Crumpp · « **Reply #223 on:** February 05, 2006, 12:00:37 PM »

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But I have never seen anyone so slick in defending his "slip" to the death as you.

Your opinion presented as fact and not worthy of discussion.

Mach .89 for a production Spitfire is laughable.

To attempt to portray it as the dive limits of the Spitfire is intellectually dishonest to the extreme.

Achieving it on a specially modified PRU version designed for these diving trials and loosing the propeller when those speeds were attained is much more plausible. Especially when instrumentation errors in transonic realm during the 1940's is factored in.

Gripen’s argument of the wing is simply laughable and quite frankly dishonest. "Mr. Aeronautics" certainly knows that the drag polar includes the wing and has seen enough production fighter variants to know he is simply spilling forth garbage to enhance his game shape.

All the best,

Crumpp

gripen · « **Reply #224 on:** February 05, 2006, 01:41:45 PM »

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Originally posted by Crumpp
You love to show that Gripen. How completely childish. Big Deal I made an error in calculation. It happens.

Actually I have not seen you to make any calculation correctly here yet. So why don't you just show how easy it's determine a polar.

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Originally posted by Crumpp

However Lets show the another portion of that thread:

All I see that you use fully calculated Fw data on Fw 190A-5 and A-8 against flight tested data on Spitfires. Using flight tested data gives a quite bit different picture.

Besides, Zigrat's spreadsheet contains errors and large generalizations as noted there.

gripen