Windmills and microwave towers?

[Derek Geldard]

Meanwhile on a new school roof in Cleckheaton (All right, all right. get it over with, it's not *that* funny) is adorned with the things like candles on a birthday cake. they look to be about 3 metres in diameter and about 5 metres high off the roof. (see website below).

The small matter of the boundary layer concerns me. No doubt when they are finished and turn out not to generate anything like the power they have been "designed" to do it will be portrayed as a failure of British Engineering.

A similar project here ...

Derek

[Dave]

I presume you are talking about Tornado here. They *can* fly damn low. I know, I spent 20 odd years on their development. Rolls Royce (Turbo Union) spent a lot of time developing the turbine blades so that the sand didn't melt and clog up the tiny cooling holes in them.

Son was a member of the crew of HMS Invincible a few years ago and they held a families day aboard it. We took a sail around the Isle of Whight and back to Portsmouth. One thing I enjoyed was the fly past by the Hawk trainer aircraft. The first time I have ever seen them from above. After that, I sat on the stern of the ship, feet dangling over the edge and looking down at the wake. There is a net all around the deck so that you would have to be very determined to jump and drown. Must be about 6 foot in width.

The aircraft's Harriers later left for servicing, but I stayed round the back of the command tower, as I had seen plenty of those take off in my job. Landing, they are good to see, if they perform.

Dave

[Andy Dingley]

The rebuilt primary school behind our house has planning permission for a small low-mounted vertical axis machine - small, but a quite reasonable installation that should work well enough (within its size limitations) on that site.

However the usual cost-cutting half-way through the project has switched this for a cheaper horizontal axis machine. Which is more sensitive to disturbed airflow, and so will be a waste of time and effort.

[Jules]

Urgh - I got that far and was impressed...

... then I continued reading :(

How come vertical axis is more expensive? Purely because horizontal is more common? The blade weight seems roughly comparable - bearing load is different, but I'm surprised it adds that much more to the cost...

[Andy Dingley]

Partly, although that's changing.

AIUI, there are two sorts of vertical axis machine: those that put one hell of an oscillating load on their (thus expensive) supports as they rotate, and those with complicated twisted blade designs that are easier to support, but need more costly ways to make the blades.

Mind you, if you want to see the horribly inflated cost of machining anything these days if the volume's small, take a look at the GWR Railmotor reconstruction period and the prices their connecting and motion rods were costing.

[Dave Liquorice]

Yep, "The Crater Makers" ... Which is why we lost so many aircraft out there.

[Andy Dingley]

9 lost Tornados: 3 (ZD718, ZA392, ZA467) by reasonable possibility of controlled flight into ground. Of the others, 3 were SAMs, 3 were various technical problems.

[js.b1]

Indeed; defined safe box & safe altitude against friendly; extreme low height to avoid radar particularly SAM. Saudi, Iraq etc are hugely hard on sand filters used to protect turbines - the maintenance is pretty severe. Helo lift off is get going horizontally as fast as possible and worry about altitude once you get airspeed up, so sand gets everywhere.

The obsession with low flying in the UK is a necessity I'm afraid, pay the penalty in noise now or lives later in exercises or combat (plus those on the ground from failed sortie to provide air cover).

The small vertical axis wind turbines can operate at high speed & produce a very loud whirring noise. They are not pleasant at close quarters, both visually & acoustically.

[Eeyore]

Any aircraft flying that low, if not intending to land would be in breach of the Air Navigation Order even in VMC.

PLANNING THE ROUTE e)........Do not plan to fly below

1500 ft AGL; it hides features, you may meet high speed military aircraft (see Safety Sense Leaflet No. 18 ?Military Low Flying?), and it reduces options in the event of engine failure.

Graham

[Dave Liquorice]

Which implies that fast jets are below 1500'. IIRC they are allowed down to 500' more or less anywhere over the country and 250' is some areas. Helicopters can go lower, 50'?

The 2MW turbines that initial work was done on planting near here would have had a blade tip height of 350'. The jets come over well below that, we can see them well enough to wave at the pilots. The Blue Meanies don't wave back though. B-)

[The Natural Philosopher]

Oh the private boys are fine. Even the microlights tend to be about

1000ft plus. The military do not though. 4-600 feet and the helicopters...yeah well.

Exactly. the military owns sub 1500, and thats where the mills will go.

[Dave Liquorice]

Round here they have a problem that the land rises rather faster than they can without putting one rather more power than they want to. I guess being a white building on a promontory that forms a bend in the valley also makes us a bit of way marker. Leave Warcop, up Teesdale (ish), over the watershed between the Tees and South Tyne, drop down into the South Tyne Valley and aim for the white blob on the hill 3 miles away as you'll be there in 20s, then exit enroute for Spadeadam. B-)

The time I complained by phone I was pleased by the response both on the phone and by letter a while later. Nothing really happened that I was aware of course. I complained that there had been a fast jet going one way over the town and then a matter of a few seconds later one went in the opposite direction at the same level. They do occasionally dog fight over us but they normally do that at >1000' and it is impressive to watch 4 fast jets trying to out maneuver each other.

[Andy Champ]

Did you hear that story about the farmer who painted "F**** OFF BIGGLES" on his barn roof? Apparently every fast jet in the country went to look...

Andy

[Dave Liquorice]

I'm tempted to put a big upward pointing arrow head with the words "PULL UP" on the gable end that faces up the valley. I don't want it visible to ordinary people though just the Blue Meanies so something to alter the infrared signature of parts of the stone wall. Any ideas?

[dennis]

Stick some "window" to the wall to interfere with the terrain following radar.

[Ian White]

Whole-wall IR LED display, programmable with your MOTD.

[Dave Liquorice]

That appeals but not to the wallet. B-)

Don't really need to emit IR(*) though just alter the heat signature of parts of the wall. Would black paint under the white do that?

(*) I don't want to dazzle the night vision camera as they fly up the valley towards us at 500mph...

[Lyn]

A very interesting question, hope someone can reply! Lyndsay

[Lyn]

paint stops some interference lyn