REFLECTOR:CONFUSION

[reflector@tvbf.org]

One more thing - reliability and maintenance.  There's a Velocity RG with 
an electric MT prop at Compton (I'm sorry, I don't know the name) that gave 
me a long tale of woe about all the things that had gone wrong with it, and 
said that (IIRC) in the 36 months he's owned it, it's been on the airplane 
about 6 months.  Fixed pitch doesn't have those problems.


At 09:44 PM 7/15/03 -0700, you wrote:
>Disclaimer - I'm not a Velocity owner.  I worked with Berkut for 8 years 
>and have one of my own, so my experience is related, but it *is* different.
>
>>I have a 173 Elite RG with an IO-540 engine.  I just spoke to Alan Shaw 
>>and he swears that a constant speed prop is NOT necessary.  He says the 
>>added weight is not worth it and it will actually cut down your cruise 
>>speeds a bit.  He said climb performance wont be a problem with that 
>>engine ... and the Velocity will be better off without the extra weight 
>>back there.
>
>We found the same.  Performance (2 place, slightly lighter, 1100 lbs empty 
>and a slightly less wing area) was terrific with the 360, and 
>mind-numbingly awesome with the 540.  We never used a constant speed prop, 
>for us the decision was 2 blade or 3.
>
>Climb will be better - but how much better do you want?  And it will cost 
>cruise speed, weight aft and cubic yards of money.
>
>>He recommended a three-blade performance prop made by Performance Props 
>>in Arizona.  He said it should be put on a five inch extension and it 
>>will fit perfectly with the cowl he designed.
>
>We had the best results from Catto.
>
>>He said the fixed pitch also helps with cooling because it can get closer 
>>to the big cowl openings on each side of the prop and it will actually 
>>suck outair creating a cooling effect.
>
>True, but only a factor on the ground.  In flight that amount of suck is 
>negligible.
>
>
>>He also said that the exhaust pointing straight out the back through two 
>>ports (bottom left and right) will actually cause a venturi effect inside 
>>the cowl ... which will force cool air to exit around it again aiding in 
>>the cooling of the engine.
>
>It may well be true, if the cowl extends beyond the end of the 
>pipes.  Augmenters that use exhaust velocity to extract cooling air have 
>been around for years, the twin Commander uses them.  But it's something 
>that's easy to get wrong - you may have the pipes sticking out too far, or 
>have the round ports too large or small or short or long and get no 
>augmentation.  Even then, you may have adequate cooling.  Hard to tell 
>without doing a bunch of oil drop trace tests.
>
>>He talked for a long time and sounded completely confident and knowledgeable.
>
>He's been around a long time.  BUT, the Atlantica scares the living 
>daylights out of me and the other people in the industry that know flying 
>wings.
>
>
>>I am getting to a point where I need to make some decisions.  Any 
>>feedback will be appreciated.  The discussions I have seen here are very 
>>intelligent and I want to take advantage of your BRAINS.
>
>As long as you are not one of the living dead and looking for a midnight 
>snack, you are free to use mine.
>_______________________________________________
>To change your email address, visit 
>http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery!  tvbf:jamaicangoose