openspaceman

Yes, I used to fell and stack cord around March and often sell the oak at stump just prior to extraction, there is often a spot of good weather in May. oak tended to be from clay sites but there would be other work year round on sandier soils. It was explained to me by an old chap that in the south the farm horses would be used for extraction and they were only available between the hay harvest and the corn harvest. It wasn't at all unusual for my forwarding tractor to sit idle in the winter months but anyone buying a £100k plus forwarder needs to keep it working day in day out.

Yes but traditionally we have not grown high quality softwoods, largely because the premium wasn't offered for clean stems, John McHardy at Longleat did instigate high pruning but I don't know whether it is paying back. It's a chicken and egg situation, similar to when corsican pine was introduced. At first sawmills milling pine only wanted scots pine and wouldn't accept the corsican pine as it came on stream from later thinnings. Once the supply of corsican increased as Theford's plantings came of age in the 80s mills converted to it and it became more difficult to find mills taking scots pine. With red band needle blight I wonder what will be done. There's a good reason for that; it often comes from places with harsher climates than ours and the growth rates are lower, as lower branches get shaded out they are snapped off by clumps of snow falling from the crown. I had a boss that liked to do spreadsheets like that, he lost millions on one project despite us telling him his figures were overly optimistic. Just think how the shape of a conifer is as it grows, basically a stem tapering evenly as it rises to the active crown and then tapering faster, like a bullet. You can only prune the steady taper without compromising growth but you want clean timber up to that point, so if you start pruning when the tree is say10cms at 5 metres it will be 15cms at the bottom, hence the clear timber will only be outside that 15cms core. Then you have to repeat the exercise at 10 metres and so the knotty core is never more than 15cms diameter uns so weiter. Given that many mills only take 45cm logs now the clear timber is only the bit from 45 down to 15. In sylviculture the concept of net discounted revenue is important to a grower, especially one that is not likely to be around when the tree is felled, basically it tries to calculate what the money today is worth to the grower compared with what he expects it might be worth at end of rotation if he invests it in the crop now. Most of the time after planting and establishment this means spending money after you have closed the gate on a plantation is resisted. When I realised how badly the sylvicultural needs were being compromised by establishment in Tuley tubes I took to trying to persuade owners to undertake formative pruning and did some on some oak trees I established, my intention was to have a 6metre clear butt but I seldom got up to more than about 4 metres. It was why I invested in a telescopic silky early on.

Well I wasn't going to butt in as I never was much of a climber, always used DDRT, never progressed further than a petzl shunt instead of a prussic knot and have been out of it for 20 years, though I did a bit 8 years ago. However it struck me what the HSE was after was a self tending belay/fall arrest system rather than arsing about with two duplicate climbing ropes. Now over on UKTreecare Bill Anderson, who seems to have a common sense approach to most things, said much the same a week ago, and suggested using a eddy current braking device which is apparently in use for climbing walls. As long as the two anchor points aren't too far apart horizontally the safety line could be redirected to be coincident with the climbing line thereafter. HSE seem concerned about a line being cut, so perhaps the attachment to the chest harness part needs be cut resistant, or perhaps the fall arrest line be a wire. Spring recoil isn't going to work over a 30metre plus range so it will need to be an active system. Some thought will need to be given to mounting and retrieving the belay, same as SRT if it is mounted at the base of the tree it will double the load on the top anchor point. BTW I'm no fan of the AA or any other club that tries to establish restrictive practices to favour members but see no point in attacking them over this sledgehammer attempt to crack a small nut.

Yes I have repaired fuel tanks cost effectively because the machine was valuable, not the same with a combi can.

Sulphuric acid H2SO4 made by dissolving SO3 in water after a complex synthesis of oxidising sulphur dioxide over catalyst (contact process) Sulphurous acid H2SO3 made by burning sulphur compounds to sulphur dioxide and adding to water. but yes it should only be a problem if it condenses as the liquid. I think I have posted pictures here of a stainless (316) flue pipe perforated with a multitude of pin pricks where a condensed weak acid from burning treated wood had run back down the flue.

Was that the dolmar engined one that wound round in a helix with a vertical chainsaw bar and dangled a release string behind? We had one in 1974 at EFG but I never saw it. A similar one came out about 20 years ago that replaced the chainsaw with a router type milling cutter. The problem with them is you need to choose and prune your final crop trees in several lifts so the knotty core is a fairly consistent diameter and clear outside that, you also need to keep 40% in crown (more in larch if there's any left) and no wounds over 25mm. With modern harvester drivers all your pruned trees would come out at the next thinning. I rode past the only remaining B&M poplar plantation that I did the first lift to 8ft on in 1974 last week. All the others were felled many years ago, the stems are clear to 8ft and knotty, useless timber thereafter.

Sulphurous acid, it should only be a problem if the flue temperature falls below the dewpoint

Didn't come through, I think:) I pressed the wrong key, it should be there as an edit now.

I'd be wary about repairing a leaking plastic fuel can. polythene is quite difficult to glue but can be welded with a hot air gun. Hot melt glue sticks are generally ethylene vinyl acetate and will stick polythene

Yes we can fairly easily calculate the amount of propane used for a given power output and thus the amount of latent heat that must be supplied from the surroundings but there will be so many variables that the proof of the pudding...

That's right and there is always a certain amount of each I imagine that is because they are separated out in the fractionating tower at the refinery. Calor blue bottles are more butane I think whilst the red bottles are predominately propane. Autogas at shell stations is near 100% propane in UK, NB Autogas is owned by Calor. The issue about the gas in the bottle staying liquid is a different thing. Plainly in the summer there is not much of a problem but in winter if it remains liquid it cannot come out of the top of the bottle as vapour whereas it will still flow out as a liquid from the bottom. So for instance as long as the coolant that flows through the evaporator in a fork lift gas truck can vaporise the liquid lpg the truck will keep running. As liquids turn to vapour their hidden energy increases, enthalpy, without the temperature going up. Consider vigorously boiling water never exceeds 100C at normal pressures. This energy has to be supplied form somewhere. What happens with a vapour take off is that as the liquid turns to vapour it cools the liquid surface, the faster you draw it off the more it cools. Thus the temperature rapidly falls below ambient if the air outside cannot supply heat through the sides of the cylinder. Hence you see a frost ring develop up to the propane level in the tanks as water vapour is frozen from the surrounding air. It's the same if you have ever tried to refill a cigarette lighter and some of the liquid spills onto your fingers, as it evaporates it makes you cold. Thus in cold weather and a bigger engine, like the 13hp Honda even a 47kg cylinder may struggle to supply vapour as the propane level drops.

A mutifuel morso squirrel on my mate's narrowboat. Mostly it runs on smokeless coal as that will keep in overnight and it gets really damp and cold if it goes out.

That's it they have got them the wrong way around. I was on the RAC site the other day and that says post 97 licences are limited to 3500 GTW instead of 4.25

Some documents include horticulture, I don't know if it has ever been tested in court On a similar subject perhaps one shouldn't believe what a .gov.uk site says Towing: licence and age requirements - GOV.UK WWW.GOV.UK

Depends what you mean by practical, I had a device made out of a 12 X 38 tractor wheel some pipe and a vacuum cleaner that was quite successful at burning stumps out. The main thing to understand is that heat rises, the next that you need to raise the whole mass, including dirt, up to 300C and it is largely self sustaining. It is also not very controllable, or insurable, I am sure I have told the story from around 1976 and the irate householder?

That's my view Also finding a back street garage is becoming difficult as they are driven out of business because manufacturers make it difficult to source information on analysing faults. not to mention how difficult it is to do trivial jobs, like having to lift the body off a Range Rover to change an alternator, or is that an urban myth?

Yes the thing is coal is mostly a solid bit of carbon, it gives off some volatiles (that's how town gas was first made) but then it just sits there glowing and not doing much. If you allow air underneath it (primary air) and a bed of hot coal to build up, the coal at the bottom produces a lot of heat and carbon dioxide, this heats up the coal above which then reduces the carbon dioxide to carbon monoxide. So the carbon is changed from a solid to a gas. The gas then combines with air supplied from over the coals (secondary air) which produces the purple-blue flame we see when the char burns. As wood pyrolyses in the fire it evolves offgas which gives 70% of the heat we feel so only 30% of the heat that comes from burning the char. Thus wood needs little primary air and that which diffuses down from the overfire air is sufficient in a little stove. It is a bit more complicated than that as unlike a petrol engine, which needs almost exactly the right amount of air to fuel, with a wood fire we always supply quite a bit more air than the ideal (stoichiometric) amount and even more as the moisture content of the wood goes up. Keeping this excess air to a minimum increases stove efficiency, hence why dry wood burns better and more efficiently.

Sounds like a project; two wheel motors on the back from a Tesla, small battery pack of about 2kWh usable, swap out the alternator with a 150V 5kW one. 100A buck converter for the 12V system with a small lead acid battery. Raspberry pi controller and then you have a hybrid with 4wd capability for a couple of miles or electric only for town. Hybrid battery charged on the overrun or under braking also gives the extra horsepower for hill climbing. I hadn't realised when I wrote that that the Citroen DS5 diesel hybrid does just this; the 28kW electric motor drives the rear wheels and the diesel motor the front. I was on a path maintenance task today and we were directed to park in a field, those that were 2WD needed a push out, the Dacia, freelander and my vitara were able to get out under their own steam but I was surprised to see the DS5 with a bit of wheelslip on front and back getting out at tickover speeds, apparently applying throttle cuts the electric drive. Apparently the PS2 platform it uses is shared with the Berlingo which is not available as a diesel hybrid.

No, although I was advised the valve seats would wear I think this only happens if you thrash the engine. Mine was a simple conversion of a venturi between each SU and the manifold with jets fed from a demand valve in the vaporiser. The V8 Rover engine was very prone to cam wear at high mileage and I had a spare high compression engine from a later Range Rover which I intended to fit (and lower ratio transfer gears) but the engine never gave any problems to I gave it to a mate when I sold the LR. I didn't tow much and then it was mostly a nifty lift. That makes sense as harder valve seats came in with unleaded petrol. It's called autogas at shell stations here in UK You could fit a tank from a motor home which you can legally and safely fill from the autogas pump. Filling another tank from that needs a bit of thinking about. The vehicle tanks have a float that prevents filling beyond 70% to prevent overpressure if the temperature goes up. If you fill an ordinary bottle it has no such safety and the space is allowed for by knowing the mass of lpg filled. It is easy to overfill and leave no space for expansion. Also forklift trucks use a liquid take off whereas ordinary bottles are vapour take off. You can buy bulk LPG for heating at less than 40p/kg but you cannot own the tank and none of the suppliers I tried would allow a tank with liquid take off, also my garden was too small for the safety margins from other buildings to have a tank at home (and they won't supply bulk LPG to a domestic dwelling that has a mains gas connection). A director of a well known forestry equipment suppliers was a hot air balloon pilot and 30 years ago he told me he refilled his balloon tanks with LPG from a bulk tank with liquid take off but never mentioned how he bought it.

mass for mass propane has a bit more calories than petrol, so buying it by the kg makes little difference. Of course we are forced to buy petrol by volume. Propane and petrol expand quite a bit with temperature so at 0C there are almost exactly 2 litres LPG per kg, at 15C LPG has dropped to 1.875litres/kg. Here's the rub, most petrol storage is underground and about 10C most of the year, LPG autogas tanks tend to be above ground so their liquid volume gets worse as the temperature goes up. I reckoned my LR 110 was good for 19-20mpg on petrol and just under 14mpg on LPG. So just over 70% per litre which is about what theory suggests. As I said earlier to get the best out of LPG you need a higher compression ratio to claw back the lower calorific value per litre, so a spark igniton engine at 12:1 should give a 12% better conversion than the same engine at 8:1 recouping about half the difference. Unless the engine has a knock sensor to retard the ignition when on petrol once converted you can only run LPG. What I was attempting to show is that filling at an autogas pump can be cheaper than buying the bottles. I was told that chicken hatcheries and gamekeepers get the best deal on 47kg bottles as they use large quantities.

They charge 70quid for 47kg near me which works out at £19/day on gas if you currently use 16 litres of petrol. Autogas near me is 60p/litre the equivalent price is £1.2/kg so 47kg of autogas would cost £56.40 even with road duty.

Edge Technology Power Ltd WWW.EDGETECHNOLOGY.CO.UK Edge Technology are a recommended authorised Honda dealership by Honda UK. Suppliers of portable and standby... I think this was the conversion used

My bad I thought you were in the area when the firm diversified into chippers.

My LR cost £1200 but I was asking if you remembered the name of Lucy's chippers

That's not the name of the conversion I remember. A firm called arboreater (I think @Mick Dempsey may remember better) equipped some small chippers about 15 years ago and it seemed such a good idea but never took off. The thing is that a cylinder of propane weighs a lot more than a tank of the same calories of petrol. Also back then the only economic size to buy was 47kg ( or a liquid draw off tank to fuel a hot air balloon, thius being the cheapest propane I'm told). Otherwise you can fill a portable tank at an autogas pump for just under 70p/litre. Thereby lies a problem, a litre of lpg only contains 70% of the calories of petrol whereas a kilo of lpg contains more calories than a kilo of petrol. Once you draw off more than a few kW of power the propane freezes in the tank, this is why propane converted cars have a liquid draw off which is then vapourised by the coolant. So a 13hp air cooled engine may draw a bit much, I wonder if an exhaust heated vaporiser exists. There are advantages in that the oil will stay golden, I ran a V8 LR 110 for nealy two decades on LPG and only changed the oil at 20k mile intervals and it was still gold. A chap on a forum I belonged to sent his oil to be analysed and it was in spec at 25k miles but the detergent level had dropped and it was a bit more acid. The thing I never got round to doing was increasing the compression ratio, thermal conversion efficiency is directly proportional to compression ratio and as lpg has a high octane equivalent it should pay to up the compression ratio. What you are looking at is what I would like to do at home but running on natural gas and a small water cooled Honda 420cc lawnmower engine