REFLECTOR: Prop size

Mon Oct 12 06:47:52 CDT 2009

Dennis,

Length shouldn't, isn't, necessarily corelated to speed.  More than a few have reported that after an 'unscheduled' shortening of the prop, they were actually faster afterward.  Long props definitely make more noise, but not always more thrust.  Despite all the study, there is still a certain art (some call it Black Magic) to prop design and mating to a propulsion and airframe system. 

Chuck 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On Behalf Of Dennis Martin
Sent: Sunday, October 11, 2009 7:22 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Prop size

Kurt,

Craig modeled my prop from his experience with other Chevy applications. I still wonder, however, if 68" maximizes my HP. Guess we'll just have to race sometime. There's no question that prop designs are influenced by black magic. So, why can't Craig make my prop longer?

Dennis

On Sun, Oct 11, 2009 at 3:40 PM, < nmflyer1 at aol.com> wrote:

Dennis, 

Well.. Good question, but I'm not the guy to ask. I recall that, when trying to find a good prop for my V, most prop makers didn't have much idea what to do unless they had tried it many times before. 
Mine is an IVO as you know (the CS Magnum version). He was the only one at the time that asked knowledgeable questions, thought about my install, and decided what would be best with what we had to work with. Because of our tremendous V-6 torque due to the redrive, he said that I would need a BIG PROP to use my power efficiently. 

Due to my density altitude and power, I decided to go with the IVO Constant speed. I also can trim the blades if need be without much hassle. Easier to trim than lengthen for sure. 

If he can "re-cut your blades longer",  he's a magician :)
Craig would definitely be the one to ask on width versus length (prop wise at least :) 

If I remember right, I have almost 10" of clearance from the hangar floor to the prop (unloaded). Looks close to me, but apparently it is fine for a Velocity 

Kurt 

-----Original Message-----
From: Dennis Martin < dennis.doc at gmail.com>
To: Velocity Aircraft Owners and Builders list < reflector at tvbf.org>
Sent: Sun, Oct 11, 2009 1:29 pm
Subject: Re: REFLECTOR: Door strut review

A 76" prop? Size matters, eh? Now we all have prop envy. I made a point of telling Craig Catto that I had lots of ground clearance, but I did not dictate the length. I assumed he would take advantage of my extra height, at least the same as yours or more (I've forgotten exact clearance). He went for a wider paddle and kept it at 68". Which is better? I haven't installed it. Should I consider having him re-cut my blades longer? 

All the best,
Dennis

On Fri, Oct 9, 2009 at 10:24 PM, < nmflyer1 at aol.com> wrote:

Al, 

My doors do not go over center to the point where there is a noticeable downward positive force on the doors. You can push them downward and let go.. then they just stop. I think I found the sweet spot for my design, in that you can gently push them upward and they will stay where you put them. 

Honestly, after paint, door panels & upholstery, another few pounds of force could not hurt, but I have not found it necessary. 

I believe my design is aesthetically better than the factory one, but folks over about 5'10" may have to duck a bit. A small price to p ay for such a nice looking aircraft.  

One more thing, I think my Velocity is taller (at the door base) than most. That is to accommodate the 76" 3-blade prop I have to (hopefully) handle my engine install. 

Patiently waiting for a nose gear 

Kurt Winker

-----Original Message-----
From: Al Gietzen < ALVentures at cox.net>
To: 'Velocity Aircraft Owners and Builders list' < reflector at tvbf.org>
Sent: Fri, Oct 9, 2009 11:34 am
Subject: Re: REFLECTOR: Door strut review

Al, 

Well I have both doors off right now, so I'll have to wait a bit to get you a complete picture. here's what I did though:

Kurt;
Thanks – I understand what you did on the reinforcing.  Mounting the strut bracket further down on the door frame gives it better leverage on the door.  Does it go over-center before the door is closed?
Al
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Dennis

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Dennis

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