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Sagitar

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Sagitar last won the day on June 1

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About Sagitar

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    Dedicated Club Poster

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  • Gender
    Male
  • Location
    Ampthill, Bedfordshire
  • Interests
    Archery and photography

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  • Vehicle
    Mitsubishi Outlander GX4hs
  1. What a lot of rust!
  2. I wonder if Boadicea is driving it?
  3. Sagitar

    Michelin Primacy 4 or Pilot Sport 4

    Absolutely right, but have you looked at the data? There have been various tests that show how little difference it makes. For example "Consumer Reports conducted a study comparing nitrogen versus air loss in tires to determine if this benefit of nitrogen was worth the extra cost. They used 31 pairs of various tire models, filled one tire of each pair to 30 psi with air and the other to the same pressure with nitrogen, then left them outside for a year. At the end of the year, they found that all tires lost pressure. The average pressure loss with air was 3.5 psi; with nitrogen the average loss was 2.2 psi – a difference of 1.3 psi over a year". And of course, if you check your tyre pressures regularly and top up when necessary, there is no difference at all. Lets suppose that you have a TPMS and you decide to top up when the pressure has fallen by 1 psi. Based on the Consumer Reports figures, if you have air in your tyres, you'll need to top up roughly once in four months. With nitrogen the equivalent figure is about once in six months. Of course, this assumes that you don't get a leaky valve, or a puncture, or decide to change your tyre pressures to correct for tyre wear, or change your "cold" pressure to correct for seasonal changes in ambient temperature, or use a tyre rotation routine that involves changing tyre pressures on front and rear tyres. And of course if you are using air, any changes are just a question of sticking on that little inflator that we all carry for emergencies. There are more places offering nitrogen now but it can still be a pain to find one.
  4. Sagitar

    Michelin Primacy 4 or Pilot Sport 4

    F1 and aircraft use nitrogen because it is dry and inert. They both operate at the extremes of performance and this makes even marginal advantage worth while. There is no similar benefit for my daily drive. The only explanation that I have seen for the early wheel changes on the Veyron is that the tyres are glued to the rims and they will not re-glue more than a small number of times. I don't know of any corrosive form on nitrogen. I worked in a hydraulics laboratory for a time where we used bottled nitrogen for every gas inflation task (because it's dry and inert). I never saw it corrode anything.
  5. Sagitar

    Michelin Primacy 4 or Pilot Sport 4

    Nitrogen makes complete sense for F1 cars and aeroplanes, but until I have an F1 car or an aeroplane in my garage, I'll not be bothering with Nitrogen . . . . . :-)
  6. Sagitar

    Michelin Primacy 4 or Pilot Sport 4

    You and I have discussed this before Tony and I can only repeat that the nitrogen issue is a big red herring. Both air and nitrogen are perfect gases and if you substitute one for the other in the gas equations you get exactly the same answer when looking at the relationship of temperature and pressure for gas in a closed vessel. The perceived differences arise because nitrogen is generated and stored in a way that does not allow water to contaminate the gas. Whereas the gas that is used to inflate road car tyres is generally just atmospheric "air" that has been passed through a compressor. The stuff that we breathe is not pure, dry air, but a mixture of air with some small quantities of other gases such as carbon dioxide, but most significantly with a variable quantity of water vapour present. Compressing atmospheric air gets rid of quite a lot of the water (watch the maintenance routine on a compressor and it's not unusual to see several litres of water drained from the receiver) but some of it gets through to our tyres. Water vapour is not a perfect gas and a tyre with a significant amount of water vapour present will give a greater change of pressure for a fixed change of temperature. But, but, but, although the change of pressure for a fixed change of temperature is less in a nitrogen filled tyre, it is not true to say that there is no change of pressure at all. Given how difficult it is to completely fill a tyre with nitrogen and to maintain it in that state, I have grave doubts whether it is worth the hassle for normal road use. I am surprised that the nitrogen red-herring is still swimming. Practical Motoring did an item on it two or three years ago called something like "Should I put nitrogen in my tyres" . Their answer was a pretty resounding "no" and they challenged the other side to answer their arguments. I don't think anyone did.
  7. Sagitar

    Michelin Primacy 4 or Pilot Sport 4

    I'm really struggling with this. I've always thought that setting tyre pressures for varied road use is not an exact science, since the actual pressure achieved while driving is subject to so many environmental variables. I have tyre pressure sensors on my car that output to a dashboard display so that I know what pressure is in each individual tyre while I'm driving. The pressure variation during a journey can be quite large. Yesterday for example when I took the car out of the garage, the tyres that had been on the cool side of the garage were showing 37 psi. The tyres on the other side were showing 38 psi. By the time I had driven a few hundred yards, all the tyres were showing 38 psi. I drove about 6 miles to a public car park and when I stopped, three of my tyres were showing 40 psi while the rear tyre on the shaded side of the car was showing 39 psi. There were similar variations on the way home. I can't say that I noticed any significant difference in the handling of the vehicle but I was driving quite gently on speed restricted rural roads. I do find it quite difficult to see how 1 psi in setting up can make such a difference when the environmental "noise" due to temperature effects can cause pressure changes that are much bigger than 1 psi.
  8. It could be a Bismarck flying fox or one of its close relatives. They are big fruit bats from Australia, New Guinea etc.
  9. It doesn't look as though it will be very good for the long term health of the dog.
  10. Spinning a curved form from a flat sheet. When I worked at A V Roe in the late 1940s we made nose cones for the Anson using this method. We did it by hand, but it's done by CNC now. Google on "spinning metal cones" and you'll find a few videos showing the process.
  11. Sagitar

    Garden Birds

    All the finches seem to like sunflower kernels, but I find that their habits change. It's not long since Goldfinches would eat nothing but nyger, but now they go straight to the sunflower seeds. We get the occasional Sparrow Hawk in the garden, but the smaller birds seem to keep a good lookout for them. The cats are more of a problem for the ground feeding birds. I often find the remains of a Wood Pigeon and I saw a cat take a female Blackbird recently.
  12. Sagitar

    Garden Birds

    We've seen no Greenfinches (or Siskins) in the garden this year, but today a lone one turned up. I managed to get a couple of shots before it looked me straight in the eye and beetled off. I still think they look more yellow than green.
  13. On the other hand, it might just mean that the animals are not visible until you have had a few drinks.
  14. Hah the niceties of English and how they are exploited by the marketeers.
  15. Sagitar

    Garden Birds

    When Blue Tits are born, they have no feathers, so they are flesh coloured. Over the period in which they are fed in the nest they gradually grow feathers which are generally in the same colour pattern as the adult but very dull. At the time they leave the nest some of their "gape" is still showing and the colours are still very dull and sometimes patchy because of the uneven growth of feathers. All of the Blue Tits in your set are well past this stage i.e. there is no sign of any "gape" so even if they are young I would still expect the colours to be close to the adult pattern. When I said some of the colours were off, I was looking at the wide differences in the background colours. Look, for example, at the colours of the bird bath. I would guess that there is more red in the first one than in the second. I can understand that your camera is set to RAW, but the pictures on the website are JPEGS so they must have be processed, either in the camera or via some processing software. Unfortunately, I don't have any pictures of newly fledged Blue Tits, but I'm attaching a picture of a Coal Tit just out of the nest. You can see that he still has much of his gape left but has already achieved most of his adult colouring.
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