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Sapphire

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Posts posted by Sapphire

  1. A picture is worth a thousand words but here is less than thousand words. In straight and level flight lift is vertically up, weight is vertically down. Drag is opposite to thrust. To maintain straight a level flight at cruise speed you need an engine [thrust] Stop the engine and you have to get thrust from gravity. By pointing the nose down you produce a forward component of lift and your vertical component of lift decreases- hense you decend maintaining cruise speed. Cruise speed is not the speed for minimum sink, so you raise the nose to reduce speed to that which gives you minimum sink or longest time in the air. If you want to glide as far as possible you pick a speed which gives you best lift/drag [not calculating headwind or tail wind] So for longest time in the air or greatest glide distance you will raise the nose from cruise speed.

     

     

  2. The bit about a two stroke running cooler at full throttle than low power is interesting. That at first forced me to do big ciruits with a long power driven final in a low drag Sapphire. Watch the EGT guage when you pull the power way back-it shoots up like a rocket. Then I read some where that the heat energy produced with the power back was not sufficient to damage the engine.[not much fuel/air] So I did more normal circuits allowing the egt to go up. Never had problems in the short term. But then, if you read around enough you can always find something that agrees with what you want to hear. So the big question is how high can the egt go in this engine before it does damage-if it does damage at all.

     

     

  3. If you know your fuel flow then you can work out your endurance[how long you can stay in the air] My last a/c did not have any fuel guage visible to the pilot and that was standard. If it has some place to put fuel and works, then you can go. Exhaust gas temp guage tells you of overheating before any cyl hd temp guage. If you fly without it you can't catch any overheating situation that would cause the engine to fail. Anyways, these small single ignition, no carby heat engines are always flown as if they are about to quit.

     

     

  4. Now don't shoot the postman Maj, but someone's gotta let you know you forgot to fill the container... Our water's still coming out the tap at just on 1kg per litre...[ATTACH=full]20703[/ATTACH]

    Definitely avoid the "heavy water" used in nuclear reactors. Use dehydrated water to save weight.092_idea.gif.47940f0a63d4c3c507771e6510e944e5.gif

     

     

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