REFLECTOR: engine size & CS prop

Ron Brown romott at roadrunner.com
Mon Feb 4 21:12:39 CST 2008


I have an IO360 200 HP and am using Craig Catto's 3 blade prop.  My first prop was a 66" dia x 72" pitch.  I got about 2250 rpm static and 2550 rpm wide open at 8000' and 172 knots.  Take off and climb was anemic.  Oh and this is on my 173 Elite RG.

I sent Craig my numbers and he repitched the prop to 66" dia and 70" pitch.  Now I get 2450 rpm static and 2700 rpm at almost wide open throttle and 165 or a bit more knots.  I have not run it wide open since it will go over 2750 or more.  I am based on a "short" runway at 3000' and 800 ft elevation - I much prefer the snappy take off (like starting off in 2nd gear versus trying to start off in 3rd gear with the original prop). I cruise at 2650 rpm and 155 knots. If I were always using a long (.4000') runway, the 72 inch pitch would probably be ok.  This pitch would probably also be required for a short wing standard fuselage - but again - on a longer runway. 

I like what I have now considering where I am based.

Ronnie Brown
N713MR for sale - see http://home.mi-connection.com/romott/  

  
  ----- Original Message ----- 
  From: Lou Stedman 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Monday, February 04, 2008 7:25 PM
  Subject: Re: REFLECTOR: engine size & CS prop


  Just out of curiosity, what is the size and pitch you have for the IO-360? Any one who is flying a Catto on a IO-360, I would love to hear what you are using. When I  purchased my Vel, it came with two three blade Cattos. They are both the same, 64-72. My problem is that I am not too happy with the RPM I get on takeoff. The best I see is about 2300. If my engine is rated a 180 HP at 2700 RPM, then I am only getting about 75% power on takeoff. Is that pretty normal? I talked to Craig Catto and he suggested that I send one back to him to take out a little of the pitch but then I would have to run at a higher RPM to get the same cruise. Just wondering what others are using. Thanks for your input.

  Lou Stedman
  Velocity N7044Q
  Olean, NY
    ----- Original Message ----- 
    From: Greg Poole 
    To: 'Velocity Aircraft Owners and Builders list' 
    Sent: Monday, February 04, 2008 5:18 PM
    Subject: Re: REFLECTOR: engine size & CS prop


    Grigore,

     

    What you have just asked about is EXACTLY what I am doing (thought I may have said this in an earlier email on this topic). While there are some very expensive fixed pitched props available, most are 18 to 25% (estimate) of the cost of a constant speed unit such as the MT - depending on whether you select 2 or 3 blade fixed.

     

    I managed to obtain a second hand (never installed) Craig Catto 3 blade with the IO-360 with extension unit that I was able to obtain from a US based builder abandoning his 173 Velocity Elite project and have heard nothing but good reports of the Catto prop in terms of performance and strength. Once flying - dollars permitting, I will be then looking to get one of the "other brands" of CS prop to get the best performance from such an efficient airframe as possessed by our Velocitys.

     

    Greg 

     greg at pooledresources.com.au 

     

     

    From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Grigore Rosu
    Sent: Tuesday, 5 February 2008 09:01
    To: Velocity Aircraft Owners and Builders list
    Subject: Re: REFLECTOR: engine size & CS prop

     

    Greg,

     

    How dificult/expensive would it be to transit from a fixed pitch to a CS propeller?  In other words, suppose that in order to get quickly in the air, one chooses a fixed pitch propeller (assuming they are easier to get, though I'm not sure about that; they are obviously cheper though).  Then in 2-3 years, suppose that one realizes that one would really like to have a CS prop.  Is it difficult/expensive to switch?  My question is probably very silly; I really have never installed a prop.  I'm just looking for options.

     

    Best,

    Grigore

    On Feb 4, 2008 3:28 PM, Greg Poole <greg at pooledresources.com.au> wrote:

    For the same reasons I gave for going with the bigger engine, I would - if the budget allows it - then go with a constant speed prop. I believe it is generally acknowledged that a  correctly set up CS prop will enable you a much wider performance envelope than what is possible going fixed pitch and will consequently get you up to flying speed much faster than most fixed pitches which tend to compromise  one end or the other (usually both!).

     

    While the factory has favoured MT props to date, they are not universally popular amongst Velocity drivers due to high service and purchase cost and very soft blades which have proven easily damaged.as a consequence, many of us await reports on other brands such as Vesta (how's it going Dave Dent?) and the one Milt is promoting.. 

     

    Greg in Sydney

     greg at pooledresources.com.au 

     

     

    From Grigore Rosu

    The recent messages on this list (for which I warmly thank you) made me switch my vague opinion to a Lyc 200HP engine.  Would an MT propeller work fine with it?  I'd like to keep things simple and safe for this airplane, and I saw lots of complaints on propellers on this list.  I wouldn't mind picking a fixed pitch propeller either (to be honest, in our club we only have fixed pitch propellers, so I have close to no experience with variable pitch ones).

     

    Grigore



     

    On Feb 4, 2008 11:33 AM, Lawrence J. Epstein, MD <ljepstein at hotmail.com> wrote:

    It all depends on your time frame. If you are a year out from engine install, then you have more options. 

    Soon after delivery of the 1st production run, DH will have a "Firewall forward (back)" kit available for the Velocity, which according to Doug (who I spent about an Hour on the phone with a few months ago), should be very complete. Therefore, I wouldn't expect it to be a whole lot more "experimental" than the Lycosaurus.  

    The first production run (awaiting delivery) includes many velocity builders (not to mention all the prototype work to date), so there should be good experience by the time your engine would be delivered.

    If you need an engine in the next 12-18 months, then I would go with the Lyco.

     

    Larry Epstein

     

    -----Original Message-----
    From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Grigore Rosu

    Sent: Monday, February 04, 2008 10:59 AM
    To: Velocity Aircraft Owners and Builders list

    Subject: Re: REFLECTOR: tools, tools, and tools again

     

    Dear Larry,

     

    I was and still am a strong supporter of DH engines.  When I ordered my kit, I was 100% sure that I'd install a DH engine in my airplane.  In the meanwhile though, after realizing how much time everything takes, I changed my mind and decided to go for a standard and well-tested configuration.  There are many much more experienced builders than me who would be happy to go for an inovation like that, because they have a much beter big-picture than I do.

    My hidden (from wife) plan is to finish this SEFG and then, while flying it, to start building a new Velocity airplane, "the airplne of my drams", that time as an "experienced" builder.  That will definitely have a diesel engine (also, I intend to eventually move back to Europe, where diesel is a lot cheaper).

     

    Grigore


     

    On Feb 4, 2008 8:16 AM, Lawrence J. Epstein, MD <ljepstein at hotmail.com> wrote:

    Since you the have the luxury of some time before you make an engine choice (I lead a very luxurious life, I started my project 12 ½ years ago), you should at least take a close look at the Deltahawk diesel. With any luck, the production engines will be delivered and flying by the time you are ready. I won't go in to the advantages here (many pages of discussion in the archives as well as their web page), but it has been engineered & tested primarily on a Velocity and as Avgas gets more problematic, a diesel looks more & more advantageous.

     

    Larry Epstein

    173 FGE

     

    -----Original Message-----
    From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Grigore Rosu
    Sent: Monday, February 04, 2008 8:59 AM
    To: Velocity Aircraft Owners and Builders list
    Subject: REFLECTOR: tools, tools, and tools again

     

    Dear Reflectorists,

     

    Thank you everybody for the valuable input on tools and the engine.  Following your advise, I'll most likely go with the Lycoming 200HP, when the time comes.  My original 160HP choice was based exclusively on range, but I see the points you made, so probably in this case less range is OK for the increase in power.  I would still be grateful for an answer on the prop arc diameter ... or is the general advice to use a little cap chain and not worry about positioning?

     

    Regarding tools, I have just made another order with Aircraft Spruce; another $200.  I think I spent close to $2,000 so far on tools; I had almost no tools when I started my project.

     

    For those who are just starting their project, please do not underestimate:

     

    1) the number and cost of tools that you will need for your airplane; better be realistic than  have surprizes.  Of course, if you can borrow tools from a friend or another Velocity builder that is great; but I am totally isolated in a university city (Urbana-Champaign) and my friends only know how to write computer programs and solve mathematical equations; never heard of something called "pipe flaring" :-)

     

    2) the amount of extra-, initially unexpected time you'll need to spend scratching your head or waiting for tools/materials.  Give each subproject a generous estimate, then triple that.  I started fitting the pilot side lower strake on January 18 and I was convinced that I would close the top strake by the end of January if I give it all my time/energy.  There were the "unexpected" fuel senders, which slowed me down a few good days: "unexpected" because they were not even mentioned in the manual, and slowed me down because I had to order and wait for them, then learn how to install, ask, etc.  Well, now is Feb 4 and I still have to wait for the "unexpected" finger strainers, the AN fittings needed for the change in plans, etc.  Assuming I receive these by Thursday and did not forget to order some important little thing which will delay me one more week, then I may have a chance to close the strake by the end of the week, say Feb 10.  Applying the reasoning above, that probably means Feb 18 or so, making it about 1 month of work for one strake only.  There is this Jeffco thing, though, which I have never worked with and which has no proper webpage with detailed explanations on how to use; I can only optimistically hope that there will be no other "unexpected" issues with it ... though there always were ...

     

    Grigore

     


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