Received-SPF: pass
 receiver=logan.com; client-ip=66.133.182.164; envelope-from=canarder@frontiernet.net
Message-ID: <4214F2E9.2000504@frontiernet.net>
Date: Thu, 17 Feb 2005 13:39:21 -0600
From: Jim Sower <canarder@frontiernet.net>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7) Gecko/20040514
MIME-Version: 1.0
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: I found the power
References: <list-742668@logan.com>
In-Reply-To: <list-742668@logan.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Paul,
I'm inquiring into the adequacy of the NACA duct(s) you want to use to 
feed your throttle body.  If I wasn't really confident that they would 
perform as advertised (it's hard to make them work really well in the 
low pressure areas of the fuselage) I'd be inclined to use a P-51 type 
external scoop like you see under right wing of Velocitys or something 
like that.

As to the prop, I would not use a prop designed for a 120 HP engine to 
make power estimates on a rotary.  I would not fly the airplane until I 
was getting at least 5000 rpm on a prop comparable to the one ED used 
when he was running his 2.17 PSRU.  Someone with a Lyc O-360 should be 
able to lend you a prop to test with for a while if your prop is a 
little radical.

5200 rpm on a 62 x 66 prop is not useful for power determination.  If 
you look at prop rpm (2390) it tells you that you have about the same 
power as an O-235 - about 110 - 115 hp.  Somehow you've got to extract a 
lot more power out of that machine.  Maybe check out your fuel flow on 
your high power turn ups and ponder that for a while.

I would not fly that airplane until I was getting good rpm with a REAL 
prop ... Jim S.

Paul wrote:

> Hi, Jim....I still had the smaller 62 x 66 prop on at the time. 
> Regarding the size of the NACA duct, are you referring to the large 
> one on the bottom of the fuselage, or the proposed two smaller ones 
> for bringing in air to my throttlebody?  Take care.  Paul Conner
>
> ----- Original Message ----- From: "Jim Sower" <canarder@frontiernet.net>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Wednesday, February 16, 2005 11:30 PM
> Subject: [FlyRotary] Re: I found the power
>
>
>> Paul,
>> What size prop is this that gives you 5600 rpm now?  Is it still the 
>> one off of the O-235 or have you gone back to your original?  What's 
>> the total area of the NACA duct (like top view)?
>> Just wonderin' ... Jim S.
>>
>> Paul wrote:
>>
>>> Today I finished installing the firesleeve on the remaing fuel 
>>> lines, made some stand-offs so that the fuel lines would not be 
>>> right up against the engine, and finished hooking up and securing a 
>>> few other items. With the top cowling off,  I ran the pumps for a 
>>> minute, then checked for leaks...none found.  Then I started the 
>>> engine and ran it for 20 or so seconds and shut it down and 
>>> reinspected for fuel leaks. None found.  I restarted and taxiied 
>>> away from the hangar a bit so as to not be as loud for others in and 
>>> near the hangar and did a full power runup.  I hit 5600 static 
>>> rpm's. In the past, the best I could hope for was 5200, most of the 
>>> time settling for 5100 rpm's.  I taxiied back in and installed the 
>>> top cowling....max rpm's 5100.  Took the top cowling back off....max 
>>> rpm's 5600.  One more try....5100 with the cowling back on.  It is 
>>> beginning to become more clear to me, that one of two things are 
>>> affecting rpm's.  Option one is that with the top cowling on the 
>>> engine is ingesting heated air and just cannot develop the same 
>>> power as when it ingests outside unheated air.  Option two is the 
>>> muffler bearing may be worn.  I'm kinda leaning toward option one.
>>>      I was thinking of installing two small NACA ducts on the bottom 
>>> of my cowling with two hoses coming up to feed air to my TWM 
>>> throttlebody. The NACA ducts I purchased from Van's RV (made for 
>>> cowling ventilation) already have a male outlet already molded in 
>>> the assembly, so you just slide a hose over it and secure with a 
>>> clamp. Very simple installation.(Works well for my cabin 
>>> ventillation) If I recall correctly, they are about the same size as 
>>> my throttle body bore. I wonder if I will loose much efficiency as 
>>> the air goes through the corregated hose, and if the Van's RV 
>>> ventillation NACA ducts will provide a sufficient volume of air. Of 
>>> course while flying, I would have the advantage of a little bit of 
>>> ram effect as well as the ability to suck in fresh outside air that 
>>> has not been heated inside the cowling during taxi/takeoff run.  Any 
>>> opinions/suggestions would of course be much appreciated.  I will 
>>> discuss the vapor lock issue in the next post, so as to not 
>>> complicate responses, etc.  Thanks to all who reply.  Paul Conner
>>>
>>> ------------------------------------------------------------------------ 
>>>
>>>
>>> No virus found in this outgoing message.
>>> Checked by AVG Anti-Virus.
>>> Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005
>>>
>>> ------------------------------------------------------------------------ 
>>>
>>>
>>>
>>>>> Homepage:  http://www.flyrotary.com/
>>>>> Archive:   http://lancaironline.net/lists/flyrotary/List.html
>>>>>
>>
>>>>  Homepage:  http://www.flyrotary.com/
>>>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>>>
>>
>>
>> -- 
>> No virus found in this incoming message.
>> Checked by AVG Anti-Virus.
>> Version: 7.0.300 / Virus Database: 265.8.8 - Release Date: 2/14/2005
>>
>>
>
>
>
>