Fwd: RE: REFLECTOR: Deltahawk engine

[J.P. Brooks]

>To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>From: "J.P. Brooks" <jp211 at comcast.net>
>Subject: RE: REFLECTOR: Deltahawk engine
>
>Al
>
>At 06:56 AM 5/6/2005, you wrote:
>>
>>Does anybody know which of the 160, 180 and 200 models can fly the longest
>>distance on a given amount of fuel, at its normal cruising speed?
>
>All things being equal, aircraft, prop, weight, DA, airframe...etc. then 
>the 160 would get you the farthest since the HP is a matter of fuel pumped 
>in and the amount of air you can force in.
>At 100% hp all the time then the distance would be more signifiacant than 
>max HP for take off then throttle back to cruise.
>If that's the case, i.e., max power for takeoff then back to long range 
>cruise the distance for a given amount of fuel would be somewhat less for 
>the 180 vs. the 160 and the same for the 200 vs. 180.
> From what I've understoond with Doug is that it is a matter of  how much 
> HP do you need.  Your fuel burn for that stated HP will be proportianatly 
> higher for more HP and less for less HP.  I'm sure Carl or Doug will 
> correct me here if my brain hasn't engaged just yet.
>
>>
>>The lowest BSFC should provide the best mpg.  In general, more speed 
>>takes more horsepower takes more fuel; but throttling back the 200hp may 
>>provide better range if it can achieve a better BSFC.  The folks at DH 
>>will have to answer that one.  Lots of factors can affect it.  Are you 
>>going to carry oxygen?  High altitude may be the key.
>
>
>
>>
>>I understand the the only "drawback", if we can call it so, of a 200 model
>>is the intercooler, which may slightly complicate the installation.  Can
>>anybody think of any drawback of the 180 model in contrast to the 160 one?
>>TBO? (let's ignore the price and assume a constant speed propeller)  I'm
>>not decided which of the DH engines to pick, so I'd like to understand all
>>the factors before choosing one.
>>
>>I wouldn't consider an intercooler a complication; but perhaps a 
>>necessity that is part of the turbo charging package.  Yes, it takes up 
>>some space in the cowling, and may get in the way for servicing, but it 
>>provides an important increase in efficiency by cooling the induction 
>>charge (increase density) that has been heated by the turbo/super 
>>charging.  One key requirement is good ducting design for the intercooler 
>>airflow to minimize any additional drag.
>>
>
>...couldn't have said it better.  We've tried many cooling intake 
>designs....   some look really "cool" but had a negative affect of our air 
>flow (shark fins out the side).
>Doug and Dave Driscoll spent many a day working the intake which is very 
>good right now.  The scoop ala P-51 would be very efficent.  Engineering 
>wise the scoop, theoretically could even be a propulsion boost if designed 
>absolutly perfect. (The  P-51 only had a 2% drag coefficient.  Pretty 
>inpressive when you see the size of the mouth on that belly.  It was
>
>>Also, another important issue: insurance!  Everything else being equal, is
>>the insurance for a Velocity with a DH engine any higher than for one with
>>a Lycoming?  Also, it seems that Deltahawk will soon certify their engine.
>>My dumb guess is that they will first certify the 160 model, in which case
>>the insurance of a Velocity with DH160 may be lower ... Any thoughts on
>>that?
>>
>>My guess is that this is not a question that can be answered yet.  My 
>>understanding is it may be more a question of whether you can, or can't, 
>>get hull coverage.  One would certainly expect that full coverage would 
>>be more attainable with a certified engine.
>>
>>My $.02 worth.
>>
>>Al
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