REFLECTOR:CONFUSION

[reflector@tvbf.org]

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.