Things you always wanted to know the answer to [Vol. 3]

[Dr Jekyll]

AstonZagato said:

Didn't some of the late WWII fighters approach Mach 1 (but not exceed it) in dives?

Depends what you mean by approach. Most experts reckon they couldn't reach it, aerodynamically impossible. It's thought that their instrumentation behaved a bit oddly at very high airspeeds which could explain the reports, but of course it could have been the approach to Mach 1 that caused the dials to over read.

[gazzarose]

Dr Jekyll said:

Depends what you mean by approach. Most experts reckon they couldn't reach it, aerodynamically impossible. It's thought that their instrumentation behaved a bit oddly at very high airspeeds which could explain the reports, but of course it could have been the approach to Mach 1 that caused the dials to over read.

Wasn't there something to do with a few Spitfires or similar crashing due to loss of control from the ailerons. Something to do with the shock wave completely enveloping the horizontal stabiliser and aileron, which led to (apparently British) boffins discovering that for super sonic aircraft a movable horizontal stabiliser is needed rather than traditional ailerons.

[dci]

Why two spark plugs per cylinder? Alfa twinspark, Mercedes 55 engine and probably many more.

Is there an advantage to multiple plugs per cylinder? Has there ever been an engine with more than two per cylinder?

[MartG]

gazzarose said:

Dr Jekyll said:

Depends what you mean by approach. Most experts reckon they couldn't reach it, aerodynamically impossible. It's thought that their instrumentation behaved a bit oddly at very high airspeeds which could explain the reports, but of course it could have been the approach to Mach 1 that caused the dials to over read.

Wasn't there something to do with a few Spitfires or similar crashing due to loss of control from the ailerons. Something to do with the shock wave completely enveloping the horizontal stabiliser and aileron, which led to (apparently British) boffins discovering that for super sonic aircraft a movable horizontal stabiliser is needed rather than traditional ailerons.

There was also a tendency for their propellers to fall off as they approached Mach 1



Squadron Leader Anthony F Martindale's Mark XI after a high speed dive to Mach 0.92

[Vipers]

dci said:

Why two spark plugs per cylinder? Alfa twinspark, Mercedes 55 engine and probably many more.

Is there an advantage to multiple plugs per cylinder? Has there ever been an engine with more than two per cylinder?

Some Mercs have two plugs per cylinder. My pal bought a used V8, bought 8 plugs thought he would change them out, only to find he wanted 8 more.

http://www.boldmethod.com/learn-to-fly/aircraft-sy...

Edited by Vipers on Monday 23 October 22:14

Edited by Vipers on Monday 23 October 22:16

[Ginetta G15 Girl]

gazzarose said:

Wasn't there something to do with a few Spitfires or similar crashing due to loss of control from the ailerons. Something to do with the shock wave completely enveloping the horizontal stabiliser and aileron, which led to (apparently British) boffins discovering that for super sonic aircraft a movable horizontal stabiliser is needed rather than traditional ailerons.

You are confusing ailerons which are on the wings (and which promote roll) with the tailplanes (the horizontal stabilisers) and the elevators (which promote pitch).

Early Spitfires had fabric covered ailerons which would distort at higher airspeeds and cause a loss of lateral control. These were changed to metal skins sometime during the production of the Mk1a which cured the problem.

[MartG]

Vipers said:

dci said:

Why two spark plugs per cylinder? Alfa twinspark, Mercedes 55 engine and probably many more.

Is there an advantage to multiple plugs per cylinder? Has there ever been an engine with more than two per cylinder?

Some Mercs have two plugs per cylinder. My pal bought a used V8, bought 8 plugs thought he would change them out, only to find he wanted 8 more.

http://www.boldmethod.com/learn-to-fly/aircraft-sy...

Edited by Vipers on Monday 23 October 22:14

Edited by Vipers on Monday 23 October 22:16

Mainly, like it says in the link, power and reliability. Used to be quite common in competition engines...

[Dr Jekyll]

dci said:

Why two spark plugs per cylinder? Alfa twinspark, Mercedes 55 engine and probably many more.

Is there an advantage to multiple plugs per cylinder? Has there ever been an engine with more than two per cylinder?

Honda 650 as used in the Deauville has two plugs in each cylinder apparently because the valve arrangement makes it impossible to put a single plug in the optimum position.

[227bhp]

mickk said:

227bhp said:

Can the house spiders I throw out at this time of the year survive outside?

I have lots of spider questions....

Don't they just come straight back in?

Never answer a question with a question so I was told.
They don't get back in because I shut the door!

[Speed 3]

RammyMP said:

Since Monarch went bust, what's happened to their planes? I thought they were all leased, have the owners leased them out again or are they parked up somewhere? If they are parked, where do they leave them?

Cheers!

Yes all leased. They went off to low-cost parking airports with maintenance/repaint capability until re-leased to another operator. Several in Shannon and Ostrava. Same story with any repo's usually. Some may already have new customers due their leases due to expire anyway or lessors knowing they were at risk. More likely to be outside of Europe tho', most operators here prefer taking additional aircraft in spring rather than start of winter.

[TheLordJohn]

227bhp said:

mickk said:

227bhp said:

Can the house spiders I throw out at this time of the year survive outside?

I have lots of spider questions....

Don't they just come straight back in?

Never answer a question with a question so I was told.
They don't get back in because I shut the door!

I read the vast majority of spiders you find in your house have never actually lived outside.

Caveat - could be complete tripe...!

[SpeckledJim]

MartG said:

There was also a tendency for their propellers to fall off as they approached Mach 1



Squadron Leader Anthony F Martindale's Mark XI after a high speed dive to Mach 0.92

Is that a big dent in the leading edge of the wing?

Caused by a propellor blade? Falling off? Whilst screaming towards the ground? At Mach 0.92!?

Crikey.

[Halmyre]

SpeckledJim said:

MartG said:

There was also a tendency for their propellers to fall off as they approached Mach 1



Squadron Leader Anthony F Martindale's Mark XI after a high speed dive to Mach 0.92

Is that a big dent in the leading edge of the wing?

Caused by a propellor blade? Falling off? Whilst screaming towards the ground? At Mach 0.92!?

Crikey.

Don't know about a dent but apparently it was the only swept-wing Spitfire in existence by the time it landed.

[The Don of Croy]

Vipers said:

dci said:

Why two spark plugs per cylinder? Alfa twinspark, Mercedes 55 engine and probably many more.

Is there an advantage to multiple plugs per cylinder? Has there ever been an engine with more than two per cylinder?

Some Mercs have two plugs per cylinder. My pal bought a used V8, bought 8 plugs thought he would change them out, only to find he wanted 8 more.

http://www.boldmethod.com/learn-to-fly/aircraft-sy...

Edited by Vipers on Monday 23 October 22:14

Edited by Vipers on Monday 23 October 22:16

Interesting answer. Our trusty Honda Jazz 1.3 had 8 plugs, whereas the later 1.4 went back to 4, but also increased power output and improved economy. Witchcraft, probably..

[anonymous-user]

Willy Nilly said:

That stroppy bird will be along in a minute to shout at you all.

Uncanny foresight

[MartG]

Is it the s or the c that's silent in scent?

[glenrobbo]

MartG said:

Is it the s or the c that's silent in scent?

Yes.

[Einion Yrth]

glenrobbo said:

MartG said:

Is it the s or the c that's silent in scent?

Yes.

Well played that man.

[Shakermaker]

Has any stolen car been recovered following a thread being put on PH and a post or two on Facebook?

We get regular threads and I see people share such stories on Facebook, but rarely do I ever see the resolution of these being thanks to the efforts of everyone as part of the community spotting it and actively recalling it is the same as a stolen one

[glenrobbo]

Einion Yrth said:

glenrobbo said:

MartG said:

Is it the s or the c that's silent in scent?

Yes.

Well played that man.