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1. 03:14 PM - Re: Rocket-List Digest: 5 Msgs - 06/08/08 (Rob Ray)
2. 03:26 PM - Re: CHT's and Fuel Flows (Rob Ray)
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| Subject: | Re: Rocket-List Digest: 5 Msgs - 06/08/08 |
Lee,
I don't know the (Harmon)Rocket cowl numbers but I will find out and get back
with you. I have found that both my RV4 and Rocket have had about a 1.5 to 1
exit to inlet...
Yep, talked to Festus and he informed me of the Piet project...cool! BTW, I run
one mag and one Rose EI, makes a big difference...
RR
--- On Mon, 6/9/08, Rocket-List Digest Server <rocket-list@matronics.com> wrote:
> From: Rocket-List Digest Server <rocket-list@matronics.com>
> Subject: Rocket-List Digest: 5 Msgs - 06/08/08
> To: "Rocket-List Digest List" <rocket-list-digest@matronics.com>
> Date: Monday, June 9, 2008, 1:57 AM
> *
>
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> Rocket-List Digest Archive
> ---
> Total Messages Posted Sun 06/08/08: 5
>
> ----------------------------------------------------------
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>
> Today's Message Index:
> ----------------------
>
> 1. 03:59 AM - Re: CHT's and Fuel Flows (Rob Ray)
> 2. 06:28 AM - Re: CHT's and Fuel Flows (Lee
> Logan)
> 3. 08:36 AM - Re: CHT's and Fuel Flows
> (CalBru@aol.com)
> 4. 11:33 AM - Re: CHT's and Fuel Flows (Tom
> Martin)
> 5. 04:22 PM - Re: CHT's and Fuel Flows (Lee
> Logan)
>
>
>
> ________________________________ Message 1
> _____________________________________
>
>
> Time: 03:59:42 AM PST US
> From: Rob Ray <smokyray@yahoo.com>
> Subject: Re: Rocket-List: CHT's and Fuel Flows
>
>
> I have a 13 year old HR2 with the stock Harmon cowling and
> a LyCon flowed 10.4:1
> comp engine. Summer temps reached 400 CHT in extended
> climbs with oilreaching
> 245.Cruise was 350-380 and 210 oil. I have read thatcowling
> outlet area should
> slightly exceed inlet area by 10%. I measured my HR2's
> cowling and trimmed
> 6 inches off the bottom lip of the cowl.Now my CHT's at
> altitude running at peak
> range between310 and 348 with 180-190 oil temp. I have
> experimented with LOP
> and see 288-315 with oil at 170. During extended climbs in
> 90+ degree FL weather
> I never exceed 380 CHT (oil has reached 230 butquickly
> cools to below 190
> when level).
> Lycon frowns on LOP operations for the 10.4:1 comp engines,
> but it cools all temps
> another 20 degrees with a 5% FF reduction.
>
> I have found even with my RV4 and 2 other Rockets I have
> helped with that cowling
> exit area needs to be opened up. My Dos Centavos...
>
> Rob Ray
>
> --- On Sat, 6/7/08, psiegel@fuse.net
> <psiegel@fuse.net> wrote:
>
> From: psiegel@fuse.net <psiegel@fuse.net>
> Subject: Rocket-List: CHT's and Fuel Flows
>
>
> On one of my early cross country flights, I had to pull
> back the rpm's a
> bit when I noticed one of the CHT's was getting close
> to my personal upper
> limit of 400'.
>
> Back home after pulling the cowl and plenum, I noticed that
> some of the paint
> on the cylinder heads had flaked partially blocking air
> flow, particularly on
> the hot cylinder head.
>
> I took great care to completely clean out all the cooling
> fins of any paint
> flakes or casting flash and I was amazed to see a dramatic
> drop in the formerly
> hot CHT!
>
>
> I am also amazed at how operating lean of peak in economy
> cruise ( I NEVER run
> LOP at high power settings) drops CHT's! Bart did a
> nice job right from
> his shop on my fuel flows to each cylinder...I sent my data
> to GAMI and they
> responded that my numbers were so close with the stock
> injectors that there was
> nothing they could do for me!
>
>
> A good rule of thumb with the IO-540's is at full
> power, take your fuel
> flow in gph and multiply by 10 (add a zero at the end of
> the fuel flow) and
> that will give you a pretty good idea of the horsepower you
> are getting. So
> depending on compression ratio, it is normal to see takeoff
> fuel flows at sea
> level in the 26 to 29 gph range.
>
> Paul Siegel Evo N4XU
>
>
>
>
>
> ________________________________ Message 2
> _____________________________________
>
>
> Time: 06:28:38 AM PST US
> From: "Lee Logan" <leeloganster@gmail.com>
> Subject: Re: Rocket-List: CHT's and Fuel Flows
>
> Rob: Do you know what the "official"
> measurements are with a Rocket cowl?
> What is the inlet area and standard outlet area with the
> lower cowl trimmed
> to the "factory" trim line? Did you end up with
> something like a 1 to 1.1
> ratio with your inlet/outlet?
>
> P.S. Don't know if you know it or not, but Festus is
> building both an RV-8
> and a Pietenpohl!!
>
> Thanks,
>
> Lee...
>
> On Sun, Jun 8, 2008 at 6:54 AM, Rob Ray
> <smokyray@yahoo.com> wrote:
>
> >
> > I have a 13 year old HR2 with the stock Harmon cowling
> and a LyCon flowed
> > 10.4:1 comp engine. Summer temps reached 400 CHT in
> extended climbs with
> > oil reaching 245. Cruise was 350-380 and 210 oil. I
> have read that cowling
> > outlet area should slightly exceed inlet area by 10%.
> I measured my HR2's
> > cowling and trimmed 6 inches off the bottom lip of
> the cowl. Now my CHT's
> > at altitude running at peak range between 310 and 348
> with 180-190 oil temp.
> > I have experimented with LOP and see 288-315 with oil
> at 170. During
> > extended climbs in 90+ degree FL weather I never
> exceed 380 CHT (oil has
> > reached 230 but quickly cools to below 190 when
> level).
> > Lycon frowns on LOP operations for the 10.4:1 comp
> engines, but it cools
> > all temps another 20 degrees with a 5% FF reduction.
> >
> > I have found even with my RV4 and 2 other Rockets I
> have helped with
> > that cowling exit area needs to be opened up. My Dos
> Centavos...
> >
> > Rob Ray
> >
> >
>
> ________________________________ Message 3
> _____________________________________
>
>
> Time: 08:36:02 AM PST US
> From: CalBru@aol.com
> Subject: Re: Rocket-List: CHT's and Fuel Flows
>
> Does the theory of a 10% larger exit area vs. cowl inlet
> hold true for ships
> with pressure plenums?
>
> Thanks, Cal
> F1
>
>
> **************Get trade secrets for amazing burgers. Watch
> "Cooking with
> Tyler Florence" on AOL Food.
> (http://food.aol.com/tyler-florence?video=4?&NCID=aolfod00030000000002)
>
> ________________________________ Message 4
> _____________________________________
>
>
> Time: 11:33:57 AM PST US
> From: Tom Martin <fairlea@amtelecom.net>
> Subject: RE: Rocket-List: CHT's and Fuel Flows
>
>
>
> Opening up the trailing edge of the cowling, or adding
> louvers will lower
> engine temperatures. I have confirmed this on a
> observations that I have
> made on my rockets. This allows more air to go through the
> system. In my
> experience this increased airflow is directly related to a
> decrease in
> airspeed. A three to four knot decrease in speed is what I
> have found when
> trimming back the lower cowling.
> I was not satisfied with reduced airspeed and an article
> in the
> august 2003 sport aviation helped me to gain back the lost
> speed and improve
> cooling. The key to the system is in the inlets. Not so
> much the actual
> size but the internal shape. The inlets need a straight or
> gradually
> increasing diffusion zone and then a smooth transition to
> the plenum. The
> seals between the inlets and the plenum need to be as tight
> as possible.
> Although I have no personal experience with the round
> cooling air inlets
> they have two main advantages. Number one is that they are
> usually located
> further forward and this allows a longer smoother
> transition zone. Secondly
> it is quite a bit easier to seal the round inlets than it
> is the rectangular
> style. By improve my inlets I noticed an immediate
> improvement in cooling.
> The decrease in cylinder temperatures was to a degree that
> I was able to not
> only return the aft cowl opening to the original size but I
> was able to
> extend the aft ramp and close the opening from stock. The
> lost speed has
> been gained back, plus a little (maybe) but the engine now
> runs where I want
> it;330 to 380CHT depending on OAT and power settings. Oil
> temps are in the
> 190 range.
> The conclusion that I have come to with my experiments is
> that there
> is not much in the way of speed gains to be made with the
> stock cowlings but
> significant improvements in cooling are attainable. I
> believe the stock
> rocket cowlings are quite efficient. Some day I will try
> some round inlets
> just to see if there are any improvements to be had there.
> I suspect that
> if you have a good stock system then there probably is not
> much to be
> gained, but I would like to confirm that suspicion.
> Currently my combined
> inlet size is 37" and my outlet area is 48". I
> do have a cowl flap but have
> found that it is really only useful in the cold winter
> months in keeping the
> engine warm during descents. This is the second plane that
> I have installed
> a cowl flap on and both instances I could find no speed
> benefits. (It looks
> kinda cool, and that must be worth something!)
>
> Tom Martin
> C-GEVO The EVO 1, 230 hours
>
>
> Checked by AVG.
> AM
>
>
> ________________________________ Message 5
> _____________________________________
>
>
> Time: 04:22:17 PM PST US
> From: "Lee Logan" <leeloganster@gmail.com>
> Subject: Re: Rocket-List: CHT's and Fuel Flows
>
> Great info (as usual), Tom. Thanks for taking the time to
> type that all
> out!
>
>
> Lee...
>
>
>
>
Message 2
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| Subject: | Re: CHT's and Fuel Flows |
Probably less Cal. I can ask Sam James, a plenum semi-expert. In my humble opinion
I would use 1% increments until I achieved Nirvana!
See ya!
Smokey
--- On Sun, 6/8/08, CalBru@aol.com <CalBru@aol.com> wrote:
> From: CalBru@aol.com <CalBru@aol.com>
> Subject: Re: Rocket-List: CHT's and Fuel Flows
> To: rocket-list@matronics.com
> Date: Sunday, June 8, 2008, 10:33 AM
> Does the theory of a 10% larger exit area vs. cowl inlet
> hold true for ships
> with pressure plenums?
>
> Thanks, Cal
> F1
>
>
>
> **************Get trade secrets for amazing burgers. Watch
> "Cooking with
> Tyler Florence" on AOL Food.
> (http://food.aol.com/tyler-florence?video=4?&NCID=aolfod00030000000002)
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