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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