Restoration is easy.

[Nick]

That's certainly a deep beam and block, did you manage to obtain a cold break when fitting the beams or was that loss factored in.

I tried to dig out the details but it was seven years ago and all the files are hidden in the loft somewhere.

I did, however, locate some photos - its difficult to accurately measure the slab dimensions now as there has been a lot of level change & concealment - the only place you can gauge the dimensions is at the junction between the old and new parts of the house - I could only find a top view of part of it... (before the old part was completely stripped out).

   

...not very helpful, but I was probably over estimating it - the slab + screed etc is about 2 ft - certainly very effective.

There is a cold break as this part of the house is "new build", but not visible in the photo above.

As we are an "older" property - about 160 years (quite recent for our village) - building standards officers were all over us for the best part of a year so we are completely up to regs as of parts L1 & L2 (2002 & 2005) - the cold break will be in there...

[Retired]

Hi,

Thanks Lawrence. The £320 gas bill I quoted was for the last quarterly bill but even so I'm not complaining because we are comfortable.

After all our roof problems when we first moved in here ending by Bron and I fitting a brand new roof to the main bungalow and over the two roomed extension I want to limit as much as possible anything which penetrates the roof at the moment this is only the chimney.

Our bungalow has 12" loft insulation which is very effective it being just over our heads. Mostly double glazed especially the rooms most used. I don't believe in cavity wall insulation as I've previously mentioned but this is the individuals choice.

The bungalow enjoys full length under floor storage; not high enough to stand in but very useful accessed by a door from the garage which the bungalow sits on; its a steeply sloping site with detached bungalows to our side of the road but upside down houses across the road with bedrooms below.

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

Whilst working at Brook Motors we used to despatch gear units from Hansen Transmission across the road; we would supply the electric motors; Hansen would attach them to their gear boxes then the completed units would be brought over on a daily basis for night loading. A few yeas ago I visited Hansen on the scrounge for a lump of cast iron and whilst on site had a good nosy around. Hansen had started manufacturing huge wind turbines and I believe the largest topped out at something like 23 tons?

Energy conservation? I can't help but wonder just how much energy has been used to manufacture one of these monsters and more to the point how many years would payback be before it even produced a profit. I mentioned to Gary ages ago that as an engineer it seems strange to me to hoist such a heavy turbine so high into the sky when wouldn't it be possible to simply design a huge fan and connect this to a large turbine on the ground via a prop-shaft thereby simplifying installation and making future maintenance much easier?

What does it cost to extract Hydrogen from water?

http://www.intelligent-energy.com/automotive

We get more than enough rainfall here in the valley for raw material; perhaps in years to come we will be installing our own hydrogen converter units; I'm certainly not clued up on these things but if Hydrogen and Oxygen are separated then they could be brought back together again to enable combustion?

I'm just thinking aloud but I get some strange ideas.

Kind regards, Col.

[pwdrive]

Thanks Nick, maybe the beams were bedded on thermalite blocks, I've to build our small extension soon, the concrete floor slab is on insulation with a foam cold break around it's edge where it abuts the foundation walls.

Lawrence.

[pwdrive]

"Energy conservation? I can't help but wonder just how much energy has been used to manufacture one of these monsters and more to the point how many years would payback be before it even produced a profit. I mentioned to Gary ages ago that as an engineer it seems strange to me to hoist such a heavy turbine so high into the sky when wouldn't it be possible to simply design a huge fan and connect this to a large turbine on the ground via a prop-shaft thereby simplifying installation and making future maintenance much easier?"

Hi Col, I guess it's down to the balance point up top (blade weight/generator weight) coupled with minimum mechanical transmission losses. I would have thought that a 200 ft vertical prop shaft would increase maintainance costs and installation costs significantly.
So far as I am aware the the energy used in their manufacture is paid back in months, not years.
As to the economics well that's another argument as so far as I am aware they are partly subsidised but then any new power station would be also either directly or indirectly, one of the first wind farms down here was at Carland Cross, the old turbines are being replaced with some new larger higher capacity ones although less in number.
The main grump down here is that some folks think they are a blot on the landscape but so are roads, cars and transmission masts both communication and electrical, acres of farmland under bright shiny polythene sheeting but we wouldn't want to be without them would we.
Don't forget that a lot of wind turbines don't go through the National grids monitoring network, as a lot are connected directly to the local distribution networks etc.

Lawrence.

[Nick]

Limiting factor on turbines, and why they have to be feathered in strong winds, is that the tips of the blades must not exceed the speed of sound at sea level - if they do, the shock wave created destroys the blade leading to the turbine being unbalanced & failing, potentially catastrophically... (see YouTube videos ad-nauseum where the braking system fails in high winds - quite spectacular!).

Typical modern industrial turbines have 40mtr to 90mtr diameter blades; Speed of sound at sea level is approx 340 mtrs/sec.

A 40mtr blade has a circumference of approx 125 mtrs, so at 163 RPM, the tips of the blades at at the speed of sound.

For a 90 mtrs diameter blade, the circumference is about 280 mtrs, so the max rotational speed is only 73RPM.

If the blades exceed this, the turbine will self destruct. The turbines have electrical and mechanical braking as well at blade pitch and yaw controls - they are complex. The generator itself is at the top to act as a counterbalance and to minimise energy loss between the blades, geartrain, brakes & turbine - the mechanics becomes a single rather than distributed package.

Power is generated using low, rather than high speed, torque so controlling blade speed to optimise torque to hit the generator sweet point is the name of the game.

On a domestic level, unless you are in some isolated croft in the Highlands, turbines make no sense whatsoever. CAT (Centre for Alternative Technology) , who have been advocating alternative energy for many many years, themselves told me that it far more efficient and cost effective to pay a bit more for "green" electricity generated on a commercial scale than to attempt to do it yourself - yes, you lose a bit of that warm & cuddly feeling, but I'd rather get it demonstrably right as opposed to trying to win brownie points at an ill-informed dinner party...

[Retired]

Hi,

Thanks Lawrence. I'm not too concerned about anything being a blot on the landscape because as you say we need lots of these things such as roads and railways. Years ago our neighbours invited us to sign a petition against a mobile phone mast which we politely refused to sign even though only recently have I bought my first mobile phone; at that time all our neighbours had mobile phones so I couldn't understand why they were up in arms; it's always OK for others to have the downside?

I agree Lawrence regarding adding a prop-shaft increasing manufacturing costs and yes such a prop-shaft would need to be long; I wonder how long the prop-shaft is in an ocean going liner such as the Titanic?

There appears to be a lot of talk regarding renewable energy but at the moment is it mostly talk and as usual until the other fuels are depleted it won't be taken seriously. Many companies are attempting to provide alternatives but as this is relatively new things such as cars which are eco-friendly seem very expensive?

Hows your Land Rover now Lawrence; I've lost track of it; did you fit the new carb OK and is it working to your satisfaction?

Kind regards, Col.

[pwdrive]

"Limiting factor on turbines, and why they have to be feathered in strong winds, is that the tips of the blades must not exceed the speed of sound at sea level - if they do, the shock wave created destroys the blade leading to the turbine being unbalanced & failing, potentially catastrophically..."

Hi Nick, I'm not an expert on high velocity mechanics but how do they manage with aircraft props and jet turbine blades?
I agree with what you say regarding very small scale installations, in an urban setting they woud be nothing much more than a gimmick for the average coffee table magazine reader, however if I had the space I would consider a small one for LV lighting/PC and telly maybe as we are more rural than urban. I did consider at one point of putting in a Rutland Windcharger down at the cabin to keep the leisure batteries topped up or even a small solar voltaic, but I don't have the time at the moment.

Col, you must be a mind reader, the Weber carb was fitted a couple of weeks ago and appears to be running ok, I took the Landrover to a garage at 8 this morning to await it's fate, it will need some work doing for sure, I will await a phone call in a day or few, I told them just to go ahead and do whatever is needed to get it through the MOT. Chassis and tanks are good ones, the most expensive part that might possibly be need is a LHD steering box at around £300 quid or so.

Lawrence.

[Nick]

Hi Nick, I'm not an expert on high velocity mechanics but how do they manage with aircraft props and jet turbine blades?

Just spoke to a pilot friend about this and he said its all very complex It seems that the speed of sound is related more to temperature than pressure - The Newton Laplace equation relates the speed of sound to the density of a gas, and the density is proportional to the temperature, so it seems that Mach 1 is proportional to the square root of the absolute temperature. Turbines & compressors run hot, so although the tips of the blades run at faster than Mach 1 if they were at STP, the air is at elevated temperature so not at STP and all is well... engines for supersonic craft go to great lengths to get the air flowing into the compressor sub-sonic before use - Concord was noted for this.

With standard prop-driven aircraft, supersonic tips are regarded as a "bad thing" - the prop makes a LOT of noise, laminar airflow over the blades is disrupted leading to a big loss in efficiency, and the shock wave can damage the blades, so again, lower revs, higher torque, more blades, dynamic pitch adjustment etc. all matter greatly.

There are planes where this can and does happen, but generally such behaviour is outside the SOA for the aircraft...

[pwdrive]

Yes, I vaguely understand, thanks.

Lawrence.

[Retired]

Hi,

Good luck with your Land Rover MOT Lawrence as these can prove very costly. A friend recently ended up paying over £700 to get her quite modern car through the dreaded MOT because of an air bag circuit fault? Bron and I are seriously considering buying a new Fiat Panda 4WD when we change our current Aygo in 18 months time. Given our valley side location and amount of ice each winter I think the time has come to sort the problem out once and for all. At the moment Avon Ice Touring pattern tyres are fitted to the front driving wheels of the Aygo but even these have been sliding around due to the road conditions. We'll test drive a Panda nearer change time.

It's fascinating to learn about wind noise generated by propellers; I knew the props on these wind turbines would produce noise but just how much noise do they produce; there are a few really big ones down the valley so would living near these be a nightmare?

It's time I went into the workshop as I've put the heating on to do something useful; what a dramatic difference to yesterday when we were out in a blizzard; it's a lovely sunny afternoon but cold.

Kind regards, Col.