Self-lighting oven

[Ric]

But have you ever tried sharpening a pencil in zero gravity?

[Christian McArdle]

I presumed that self propelling types were specified, but maybe I'm wrong.

Christian.

[Mungo "two sheds" Toadfoot]

Thanks Ed, I think it's this. If I give it a gentle (heh) bash when it's not working, it does.

Si

[Pete C]

Urban legend, though in weightless conditions bits of pencil lead won't be any good to your electronics.

cheers, Pete.

[Ian Stirling]

Coloured pencils are free of even this small hazard.

[Ric]

What about crayons?

[raden]

Now that's where you're wrong. The cooker ignition circuit was developed (along with PTFE) by NASA scientists for lighting Saturn 5 rockets from a distance after they had several failures with the "light blue touch paper and retire to a safe distance"

Tiles, of course, were invented for making Space Shuttles look cool and sparkle on re-entry, although the use of "No More Nails" to stick them on with might not have been the best idea

[raden]

In message , Ric writes

That's what the monkeys gave the cosmonauts to use

[raden]

Yes, I've seen them used in Australia

[IMM]

A flame can support an electrical current. When there is a flame between the contacts no spark, when not it jumps the gap. A flame also acts as a diode, called flame rectification, which is also used for proving. I first came across it in the mid 1970s.

I have a Thorn Moffat hob which has this ignition method, the best. If the flame blows out it sparks until it relights. The hob is 24 years old and still looks like new. It beat my new Neff by a mile, which consider naf and its ignition system is a switch the know hits as it is turned on. If you turn too fast it misses. Way behind the Thorn. German engineering?

[SteveS]

"raden" wrote >>

It's untrue, BTW, that Teflon came out of the Apollo program. PTFE was actually discovered accidentally by Roy Plunkett at DuPont in 1938. It was first used for making gaskets and seals resistant to uranium hexafluoride during the Manhattan Project. It might not rocket science, but nuclear physics, perhaps.

Steve S

[Andrew Gabriel]

However, it took years to work out how to make it stick to the bottom of a saucepan, and those who remember the first teflon pans will doubtless recall that it didn't stick for long ;-)

[raden]

In message , SteveS writes

Is that where they first learned to extract urea

[SteveS]

Just pointing out a popular misconception. No need to get sarcy.

[raden]

In message , SteveS writes

I've never been driven by necessity

You could also have pointed out that they didn't light the blue touch paper to start Saturn 5's, IIRC it was usually orange

[IMM]

After a while you will get to know that Maxie has problems. You have to treat him nicely.

[raden]

In message , Owain writes

Didn't another thread degenerate into exactly the same discussion last week ?

[raden]

In message , "Mungo \"two sheds\" Toadfoot" writes

Mirrors and magic Si

As they say, keep up at t'back

Just the same as ignition circuits in central heating boilers (which must get discussed at least once a month), a flame acts like a resistive diode, which is what the flame sense circuit senses

Electrode not properly in the flame, intermittent contact on the HT lead, bad earthing, gremlins just out to get you.

[Owain]

"raden" wrote | In message , Owain writes | >Presumably there must be a similar mechanism on rockets to ignite | >them? I can't see NASA sending out for some two-furra-pound gas | >lighters every time they want to do a launch. | Didn't another thread degenerate into exactly the same discussion | last week ?

I posted that last week (Wed 22/9/04). Perhaps the Internet magic string is soggy in places.

Owain

[Mungo "two sheds" Toadfoot]

Shaddup :)

It's all clever stuff, innit? It's stopped working completely now, btw. It

*is* gremlins!

Si