JDK's Infamous Quiz Returns! No.65742 pt.B

JDK · **Posted:** Sat Jan 22, 2011 10:23 pm

This one is tech fact trivia question, and (I hope) may well start a discussion after it's been solved.

The Spitfire, Mustang, and 109E had it, the Hurricane, P-40, and Typhoon didn't.

What is it?

Usual rules: Mike can't play, no ponies but a warm feeling to the winner, points for details, references and digressions, of interest.

Tiger Tim · **Posted:** Sat Jan 22, 2011 10:50 pm

This is just a straight out guess but could the thing in question be a one-piece wing?

-Tim

Edited six seconds later to add, "No, it can't. The 109 for sure had a wing panel bolted on either side of the fuselage. Something to do with ease of manufacture or maintenance or something"

Well, I'm out of ideas.

12XU2A3X3 · **Posted:** Sat Jan 22, 2011 10:57 pm

no self sealing on early models of the second group?

Zachary · **Posted:** Sat Jan 22, 2011 11:27 pm

Two-stage supercharger? :?:

bdk · **Joined:** Sun May 02, 2004 1:16 am **Posts:** 11324

Adjustable radiator inlet?

bdk · **Joined:** Sun May 02, 2004 1:16 am **Posts:** 11324

Retractable tailwheel?

JDK · **Posted:** Sun Jan 23, 2011 12:53 am

No, no, nopedy no...

Also users - CAC CA-15 and Martin Baker MB-5, and [probably - I'm not sure] the Fisher XP-75 Eagle.

Dan K · **Posted:** Sun Jan 23, 2011 1:01 am

Relief tube?

JDK · **Posted:** Sun Jan 23, 2011 1:39 am

Nope!

One poster's touched on an aspect of it, but not really the right level.

I'm looking for a name - and some science.

The 109E's example wasn't particularly evident, nor I suspect as effective as the others. But it did have two, like the later Spitfires (but not the early ones) and all the others only ever had one.

Rick65 · **Posted:** Sun Jan 23, 2011 2:04 am

adjustable radiator outlet (use of Meredith effect?)
Has to be something to do with radiators - the Spit reference is a clue as they had one for the early and two for the twin stage) but I don't know enough about the 109 for the E reference to help.

JDK · **Posted:** Sun Jan 23, 2011 2:10 am

Rick65 wrote:

adjustable radiator outlet (use of Meredith effect?)
Has to be something to do with radiators - the Spit reference is a clue as they had one for the early and two for the twin stage) but I don't know enough about the 109 for the E reference to help.

I'll take it! They all has one (or two) Meredith Effect radiator ducts. The adjustable intake (bdk) or outlets (Rick) improve efficiency and cope with greater / lesser demands but are not in themselves critical to the system, which simply put is sort-of a reverse venturi structure.

I was reminded of it by the discussion of the P-51 prototype accident thread.

http://contrails.free.fr/refroid_meredith_en.php

http://en.wikipedia.org/wiki/Meredith_Effect

Rick65 · **Posted:** Sun Jan 23, 2011 2:28 am

JDK
Thanks for the quiz.
Can you (or others) explain the reference to the 109E - was that the first 109 to use the principle or did all the 109s with wing radiators?
I know some of the the very early 109s had chin radiators.

JDK · **Posted:** Sun Jan 23, 2011 3:02 am

Rick65 wrote:

Can you (or others) explain the reference to the 109E - was that the first 109 to use the principle or did all the 109s with wing radiators?

I'll try, but I'm no expert... The 109E had small wing rads, but while the intake was just the depth of the housing under the wing, the radiator was also the full internal height of the wing as well, and they had an adjustable outlet flap; how much or how efficient it was as Meredith effect, I don't know. The 109G onwards had a larger flatter-looking radiator set up with the aircraft's flaps forming part of the outlet and an adjustable intake lip; again, I presume proper Meredith.

What gets interesting is where you look at the effect in aircraft like the Fw 190D, and other close cowled radials.

As they say, discuss!

Rick65 · **Posted:** Sun Jan 23, 2011 8:29 am

I have read the Meredith effect credited as the reason that the P51 was more aerodynamic than the Spitfire, giving a faster plane and better fuel usage from similar motors. The P51's laminar flow wing is the other obvoius difference but the effectiveness of this in the real world is often debated.
Until this discusion I had thought that the Spitfire gained minimal advantage from the Meredith effect while the P51's radiator setup was far more effective, presumably due to the greater space available and consequent more efficient design.
Can any one comment? (JDK - you did want discussion)

JDK · **Posted:** Tue Jan 25, 2011 7:41 pm

I've just been passed a few thoughts from someone with an aero engineering background, but as they say, no specific data on the cases. Nevertheless it matches the structures I'm familiar with, and I thought it worth sharing:

Quote:

...the Griffon Spits had a positively awful radiator housing design. Although part of the radiators were inside the wing, they stuck out horribly and were not well streamlined. The B and later Mustangs also had a lip on the top of the scoop that stripped away the boundary layer from the bottom of the wing, only allowing clean undisturbed air into the radiator diffuser. It was a brilliant design perfected in the wind tunnel. While the Spitfire design might have overcome some drag by utilizing the Meredith Effect, I doubt it actually created thrust in excess of drag as the Mustang design did.

Sounds reasonable to me - the boundary layer stripping is very obvious and the 'gap' between the inlet and the wing underside was progressively increased in the early Mustangs.

Anyone care to comment? 51Fixer?

Quote:

I have read, again with no citations in front of me, that the Tempest chin radiator was also very well designed.

That'd be interesting; anyone got data?

Regards,

Warbird Information Exchange

JDK's Infamous Quiz Returns! No.65742 pt.B

Who is online