REFLECTOR: Re: Props

Jim Sower canarder at frontiernet.net
Tue Jun 28 14:58:35 CDT 2005


Chuck,
Chuck Harbert wrote:

> Jim, I've got a similar setup (200 hp IO-360 in Std RG) and I'm also 
> overproped (2200 static), but I'm doing over 180 kts @2700 rpm using a 
> What size? Catto prop.  That's strange.  I get the same static as you, 
> but I only get 2500-2550 cruise.  I'm guessing that the FG, no wheel 
> pants, etc. that slows me down to 145-150 kts cruise is causing some 
> of that.  If I was cruising at 155 kts the rpm would probably increase 
> a little (maybe 50-100?).  I have a turbo system ready to install 
> which will bring up the static to 2,400 rpm and I'm expecting higher 
> speeds at higher altitudes at below normalized MP which is what Catto 
> designed my prop for. My t/o roll is a bit longer, but still less than 
> 2,000'.   My takeoff roll is hideous on account of 450-480 lb front 
> seat load.  Working on that too.  I'm down 40# since the first of the 
> year.
>
> I think the combination of FG (w/o wheel pants) and the 173 wings can 
> significantlty reduce the top speed.  I think so too.  I definitely 
> would not switch to a Mazda rotary (I switched from a rotary) as it 
> will take a long time to install, and will not produce the power, fuel 
> burn, or reliability you're looking for.   I plan on setting the whole 
> thing up on a firewall mockup so as to minimize the installation time 
> and effort.  What'd you do with your rotary? :o)   If you want higher 
> speeds, the only realistic way is to turbocharge and take advantage of 
> the reduced drag (thin air) at higher altitudes.  I plan on using 
> Tracy's RD1C (2.85:1) redrive and running the engine at 7500 rpm.  
> That should buy me around 220 *acutal* hp as opposed to Lyc's 200 
> *marketing* hp. This assumes you've done everything aerodynamically 
> possible.  I still have a lot of aerodynamic fixes to do.  Wheel 
> pants, get rid of oil cooler scoops, etc.  That should buy me another 
> 10 kts at least
>
> If you're only getting 2,550 max rpm, you're losing 20 hp compared to 
> 2,700, and probably 5-7kts. Catto told me he can modify the prop to 
> get higher cruise rpms, plus you'll pick up some static rpm and better 
> t/o performance.   I'm going to have Craig repitch my prop after I do 
> the aerodynamic stuff and have a better idea how much I need.  Might 
> just trim an inch off each tip.  That would make my 66x72 into a 
> 64x72.  That might just get me going well enough to where I can 
> revisit the rotary issue.
>
> Good luck.
>
> Chuck H
>
> --------------------------------------
>
>> Date: Thu, 23 Jun 2005 23:54:26 -0500
>> From: Jim Sower <canarder at frontiernet.net>
>> Subject: Re: REFLECTOR: Props ...
>> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>> Message-ID: <42BB9202.9060403 at frontiernet.net>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Scott,
>> Where'd you get 180 ktas?  You got an RG?  If not, I'm humiliated.  Mine
>> (w/o wheel pants) won't do a yard over 150 kts.  I have to file 145 or
>> 140.  It's embarrassing.  Looks like I might have to bite the bullet and
>> do all that work and install a 220 hp Mazda.
>>
>> Love the engine, hate all that work ... Jim S.
>>
>> Scott Derrick wrote:
>>
>>> Jim,
>>>
>>> "I had" the same engine, rated 200HP.  I was running a Catto, 64x74.
>>> I would get 2350 static, and WOT 8000,  2800 RPM, 180 KTAS. That was
>>> with a LSE ignition which I think added to my performance.
>>>
>>> I never cruised at 2800, I would normally cruise at 2700-2750,  at apx
>>> 175 KTAS, 75 LOP.
>>> You could cut a 1/2 inch at a time, off of it,  and see how it
>>> increases your RPM?  2550 WOT is definitly over propped. You get that
>>> static up to 2350 you'll cut 500+ ft off your take off roll.  Your
>>> cruise speed would be less because of your bigger wing.
>>>
>>> Scott
>>>
>>> BTW, my prop with a Saber 8" extension is for sale $1500 + shipping.
>>> 300 hours. I'll put a new coat of PPG on it before shipping. You pick
>>> the tip color.
>>>
>>> Jim Sower wrote:
>>>
>>>> All,
>>>> I am running an angle valve IO-360 with a Catto 66x72 on my 173-FG.
>>>> I find I'm overpropped about 200 rpm,.  I get 2200 - 2250 static and
>>>> 2500 - 2550 WOT at >8000'.  I think I'd be a lot happier with closer
>>>> to 2400 - 2450 static and 2700 or more at 8000'.
>>>>
>>>> Who's got a similar engine, what kind of prop are you using, what
>>>> static and cruise (>8000' WOT) rpm are you getting?  I think my
>>>> engine's pretty sorry, but I don't have any other data points from
>>>> similar engine prop combinations.
>>>>
>>>> Thanks in advance ... Jim S.
>>>> _______________________________________________ 
>>>
>
>
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