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Downunder

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Posts posted by Downunder

    Design and build an 'Ultralight'

    in AUS/NZ General Discussion

    Posted

    I'm a bit late on the scene but for your prop hub, there are combined bearings with both radial and thrust properties built in. See the SKF web site.

     

    SKF Group - Bearings and units Lubrication solutions Mechatronics Seals Services - SKF.com (Rolling Bearings)-Angular contact ball bearings,

     

    Combined needle roller bearings,

     

    Probably need a shoulder on the mounting sleeve (to push against) or a good way of fixing the inner race.

     

    Regards,

     

    R J Mitchell

     

     

    Internet monitoring software

    in AUS/NZ General Discussion

    Posted

    Hello, Is there a program which can monitor my internet connection. I keep having brief pauses(a few seconds) in my connection which sometimes cause a disconnection. My ISP blames my computer. But I'm not so sure.

     

    All programs connected to the internet at the time cannot transmit or receive.

     

    Tried disabling my anti virus but no different. I'm on cable.

     

    Regards,

     

    R J Mitchell

     

     

    The Heat.

    in AUS/NZ General Discussion

    Posted

    Hello,

     

    From my work in the mining industry, I know a bit about dehydration and heat stress.

     

    If the person is incoherant and dizzy, seek medical help immediately.

     

    They may not rehydrate fast enough just drinking and require saline drips.

     

    Heat stroke is Very life threatening.

     

    Check your hydration level by the colour of your urine (yellow is bad)

     

     

    Cold comfort..

    in AUS/NZ General Discussion

    Posted

    Coming home from work (mine site) in a Cessna Conquest, I was a bit blocked up.

     

    Decent was closer to a dive (airspeed knocking on the barbers pole). Well, the pain was unbelievable. Felt like my head was going to explode. I always carry mints or cold lollies now.

     

    I was on a Qantas flight once, and another passenger had blocked ears and was in some pain. The stewardess had some sort of smelling substance that she gave to the passenger which quickly relieved the passenger. Does anyone know what it is?

     

    It looked like a small tear open pouch.

     

     

    Some sad news - prices

    in Other Rec Aircraft

    Posted

    Hello, I'm not really surprised at the cost of the millennium. The exchange rate to any of the European coutries has been terrible for a while. The US is (was?) a far better return for the A$. The problem with the US manufacturers is that they are building/designing to suit the US rules/regs and our less restrictive rules mean that perhaps these aircraft are not developed to their full potential for the Australian market. It would be great if the yanks came out with an "Aussie special" version of their kits.

     

     

    160cc motors

    in Other Rec Aircraft

    Posted

    Hello, I guess what I'm trying to say is that you can get the power without the weight of the victas.

     

    Less weight, lighter airframe.

     

    Not having the weight of outboard engines would give you less stress on the wings wouldn't it?

     

    Can't see free wheeling props adding drag.

     

    I recon you could use 2 engines with more power than the victas and at a lot less than half the weight.

     

    The 3W engines are not cheap but that was just an example of whats around.

     

    Ofcourse if you really want those mower motors to fly then by all means go for it !!!!:big_grin:

     

    Regards,

     

    R J Mitchell

     

     

    160cc motors

    in Other Rec Aircraft

    Posted

    Hello,

     

    Alot of RC aircraft engines run at around 40/1 oil/fuel ratio, so I think 25/1 maybe conservative. They also rev up to 10 000 rpm. I don't have any knowledge of the victa engines however.

     

    4 hp from 160cc looks to be extremely poor. You can buy cheap chinese RC engines for $200 that are 50cc and produce 4hp. weighing 1.5kg. I'm definately not saying you should use these but just showing an example.

     

    A 3W210 (210cc, german made, high quality, twin spark, 4.8kg,31x12 3blade prop) makes 21hp.

     

    Have you thought of having inboard engines only with free wheeling props outboard? What about larger engines inboard and smaller out? You could have the same dia props with different pitch.

     

    Regards,

     

    R J Mitchell

     

     

    calculate the force on a big end Bearing

    in Engines and Props

    Posted

    Here is a con-rod with bronze bearings.

     

    Oil content required is approx 15 to 20%.

     

    Having spent some time looking at advanced plastics, ceramics and alloys, I may be close to trialling a product with better properties than bronze.

     

    This would allow a lower oil content. More power and less pollution.

     

    There are ways to improve crank-pin strength, to compensate reduced diameter.

     

    Heat treatment, material selection, etc

     

    Engine manufacturers produce engines to a budget. There is always room for improvement.

     

    Regards,

     

    R J Mitchell

     

    supg2577.jpg.6f1be80218b48f380dac4fd5dd3c76dc.jpg

     

     

    calculate the force on a big end Bearing

    in Engines and Props

    Posted

    Thanks all for your replies.

     

    It will in fact be for an aviation engine(sort of).

     

    Lowering of the diameter of the crankpin reduces the rotation speed (Meters/Second) on the bearing.(need this for the material I'm looking at). It revs quite fast as a small 2 stroke would.

     

    Normally a needle roller bearing would be used, but the physical size and composition of the conrod becomes an issue.

     

    A sintered bronze bearing may have lubrication and heat issues at the oil mix I want to run. More oil = less power.

     

    There are many modern materials being developed all the time.

     

    If I can find the "force in newtons" that I seek and am able to keep the rotation speed down, then I may be on to something.;)

     

    Thanks again,

     

    R J Mitchell

     

     

    calculate the force on a big end Bearing

    in Engines and Props

    Posted

    As the heading states, I need to calculate the force in newtons of a big end conrod bearing onto the crank pin.

     

    Is there an online calculator, or formula?

     

    Would the same force apply to the piston pin bearing.

     

    Obviously the force of the piston pushes the rod down and then the counterweght brings the piston back up(single cylinder) so there maybe a calculation for average and maximun force?

     

    Probably not as simple as that?

     

    The engine would be two stroke petrol with oil mix.

     

    I should say this is part of an alternative bearing material investigation and will not be used in a man carrying aircraft.

     

    Any help or tips would be appreciated.

     

    Regards,

     

    R J Mitchell

     

     

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