Hi Wayne,
I take on board and accept what you are saying and it certainly makes alot
more sense to try and play with what I got before spending any monies only to
find little or no improvement.
Am I right in thinking that if I pitch the prop to achieve the 2800rpm then
it is going to be quite fine (it is 11.5 now, measured 4" in from the tip and
achieves the 2100(ish) static rpm. I accept that I will climb out like a
scaled cat but when I throttle back in the cruise, say 2300rpm, then I am
still going to be turing a very finely pitched prop (save for the twisting
effect) is this going to have a significant negative effect on performance.
I understand the analogy given earlier about the bike and the different
gears. I think I will be pedalling a mile a minute in the cruise but gettig
nowhere. Just a thought.
I will definately play around with the pitch etc before doing anything, sound
advice.
A further thought, my understanding is that the L2C is rated for
105/112/115/118 hp at 2400/2600/2700/2800 rpm. The hp is governed by the
prop specified for the aircraft presumably to prevent exceeding design
limitations. Now this is all given that they have standard 8.5:1 pistons
(this maybe where I start to go wrong) so in this case you could wind up the
engine to 2800rpm and produce 118hp but then throttle back and accept less
hp. Now remove the std pistons and install the 108hp pistons and the whole
ball game changes. Even by winding up the engine to 2800rpm you will not get
the 118hp output. You will be reving it away but no extra thrust being
developed.
I will check my flap settings again because I am certain mine go down to a
barn door 30degrees. I will certainly try the 18degree inital setting to get
airborne then lose a notch.
Thanks,
Bob
On 5/1/2003 11:33 PM,
OIFA@IRISHFIELD.ON.CA wrote to MURPHY-REBEL:
-> From <
oifa@irishfield.on.ca> Thu, 01 May 2003 13:26:39 -0800 remote from
dcsol.com
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murphy-rebel@dcsol.com; Thu, 01 May 2003 17:26:43 -0400
-> Message-ID: <002101c31027$b68ae230$e401910a@celeron266a>
-> From: "Wayne G. O'Shea" <
oifa@irishfield.on.ca>
-> To: <
murphy-rebel@dcsol.com>
-> References: <
E19BG3C-0002E3-00@app5.nasc.inter.net>
-> Subject: Re: lycoming 0-235
-> Date: Thu, 1 May 2003 17:22:02 -0400
-> Organization: O'Shea's Irish Field Aviation
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->
-> Bob, I echo Bob Patterson there! Take some pitch out of that WD and run the
-> shit out of it!! I am speaking from experience here as I told you before I
-> had the O-235-C model on my Rebel originally and it was only 100HP@2600RPM.
-> When I changed from my wood prop to the WD (3BLADE x 70") I was already on
-> skis and tried setting the prop pitch to give a similar 2250 RPM "static
-> tied to a tree" that you would with a metal propellor. The airplane at full
-> power would just barely move in the snow and I thought I had wasted a big
-> chunk of change buying the WDrive. I then repitched to get 2450 to 2475
-> static. At that pitch it jumped out of the snow and climbed at approx
-> 1400FPM (flight weight about 1400lbs). Even with this high of a static RPM
I
-> could not readline past the 2600RPM unless I stuck it in a dive! The WD
-> seems to twist while in flight and gets a little coarser once you start
-> bitting air, sorta like a constant speed prop.
->
-> Knock on wood, my 70" WD is still crack free after 6 years. 2 1/2 of them
on
-> the O-235 and 3 1/2 using the same propellor on my O-320-C2A x 150HP.
->
-> Try playing with the prop before you spend any money on the engine. If it
-> was originally a 118HP engine then it has no internal reason why you can't
-> use 2800RPM for take off (5 minutes) and 2700 continuous.
->
-> As for the flaps, if the stick is centered they indeed only go down 18*
-> (well you can sneak it to 23* actually). When you move the stick left/right
-> they indeed go further down so the sucker will turn, but you should have
-> about three notches set at 6*/12*/18* or at the most 7*/15*/23*. I always
-> use full flaps when on skis to help lift me up out of the snow. Same thing
-> applies in heavy grass etc or a short field to get her off the ground, then
-> dump a notch for climb out.
->
-> Cheers,
-> Wayne
->
-> ----- Original Message -----
-> From: "Bob Patterson" <
apat@istar.ca>
-> To: <
murphy-rebel@dcsol.com>
-> Sent: Thursday, May 01, 2003 11:32 AM
-> Subject: Re: lycoming 0-235
->
->
-> >
-> > Hi Bob !
-> >
-> > Adjusting your W-D to give you about 2,500 (+ ?) static will
-> > at least tell you if you're going the right way ....
-> >
-> > If that does improve your takeoff, then you could feel better
-> > about going to the Sensenich. It's probably a good decision.
-> >
-> > The flapperons on the Rebel produce more lift than drag,
-> > especially at low speeds. I always take off (and land) with full flap,
-> > as this reduces the ground roll, and the speed. You can drop to
-> > 2 notches for climb, once out of ground effect - some playing around
-> > will find the best climb setting... it might even be one notch,
-> > with the O-235...
-> >
-> > .....bobp
-> >
-> > -----------------------------------orig.-----------------------------
-> > At 11:34 PM 4/30/03 -0800, you wrote:
-> > >Hi Bobp,
-> > >
-> > >Thanks for the reply,
-> > >
-> > >Sounds like the wd probably is on the short side, WD themselves said
-> 'about'
-> > >68 or 70, I was working on the premise that 72" on a 2 blade may be
-> similar
-> > >to a the thrust available from a 68" 3 blade, but truth is I do not
know!
-> I
-> > >suppose what is important is the area that the thrust is actually out
and
-> > >beyond the cowling, and the farther out the faster the tip must be
going.
-> > >The blades on the wd are not very deep across so this prob has an
adverse
-> > >effect as well.
-> > >
-> > >On takeoff I have never tried full flap but, have limited it 10 degrees,
-> I
-> > >would have thought full flap would also increased the drag considerably
-> and
-> > >defeat the object????
-> > >
-> > >Thanks for you input, I will keep you posted
-> > >
-> > >Bob
-> > >
-> > >
-> > >
-> > >On 4/30/2003 11:26 PM,
APAT@ISTAR.CA wrote to MURPHY-REBEL:
-> > >
-> > >-> From <
apat@istar.ca> Wed, 30 Apr 2003 17:59:02 -0800 remote from
-> dcsol.com
-> > >-> Received: by dcsol.com (Wildcat! SMTP Router v5.6.450.61)
-> > >-> for
murphy-rebel@dcsol.com; Wed, 30 Apr 2003 17:59:02 -0800
-> > >-> Received: from nasc-out-1.nasc.inter.net ([203.176.60.253])
-> > >EHLO=app6.nasc.inter.net
-> > >-> by dcsol.com (Wildcat! SMTP v5.6.450.61) with SMTP
-> > >-> id 114281171; Wed, 30 Apr 2003 17:59:00 -0800
-> > >-> Received: from 2cust75.tnt23.toronto.on.da.uu.net ([64.10.100.75])
-> > >-> by app6.nasc.inter.net with smtp (Exim 3.34 #1)
-> > >-> id 19B3Ln-0006ew-00
-> > >-> for
murphy-rebel@dcsol.com; Wed, 30 Apr 2003 21:59:07 -0400
-> > >-> X-Sender:
crs1188@pop.ca.inter.net
-> > >-> X-Mailer: Windows Eudora Light Version 1.5.2
-> > >-> X-Orig-Mime-Version: 1.0
-> > >-> X-Orig-Content-Type: text/plain; charset="us-ascii"
-> > >-> To: <
murphy-rebel@dcsol.com>
-> > >-> From: Bob Patterson <
apat@istar.ca>
-> > >-> Subject: Re: lycoming 0-235
-> > >-> Message-Id: <
E19B3Ln-0006ew-00@app6.nasc.inter.net>
-> > >-> Date: Wed, 30 Apr 2003 21:59:07 -0400
-> > >->
-> > >->
-> > >-> You might be right about your prop - most folks here have
-> > >-> used 70" or 72" diameter Warp Drives. The Rebel is pretty 'fat',
-> > >-> and that short prop might not be moving much air past it !
-> > >->
-> > >-> The original O-235 was 100/108 hp. - the 100 was max. cont.,
-> > >-> and the 108 was for 5 min. at takeoff. I believe that was with
-> > >-> 6.5 to 1 pistons - about what you have. The HP rating was at
-> > >-> 2,600 rpm, as I recall - so it sounds like your W-D was also
-> > >-> pitched a bit too coarse ...
-> > >->
-> > >-> I do remember that the O-235 liked to be cruised fast,
-> > >-> and was happiest cruising all day at 2,450 rpm...... certainly
-> > >-> no danger of harm, as long as your temps are ok.
-> > >->
-> > >-> As for getting the Rebel off the ground, I assume you
-> > >-> are using full flap for takeoff ??? That's what the flap is
-> > >-> there for !!! You can back off to 2 notches after you are out
-> > >-> of ground effect - but using all of it should definitely get
-> > >-> you up faster.
-> > >->
-> > >-> If you still have the W-D, I would just tweak it finer
-> > >-> to give you at least 2,500 static rpm, and see if that helps...
-> > >-> If it does, then going to the Sensenich will likely be a
-> > >-> "Good Thing"(tm). ;-) :-)
-> > >->
-> > >-> Keep us posted ! Good luck !
-> > >->
-> > >-> ....bobp
-> > >->
-> >
-> >-> ---------------------------------orig.---------------------------------
-
-> --
-> > >-> At 12:02 AM 4/30/03 -0800, you wrote:
-> > >-> >Hi Bob,
-> > >-> >
-> > >-> >Thanks for the reply, as with Drew I did reply earlier but seems it
-> did
-> > >not
-> > >-> >get posted either.
-> > >-> >
-> > >-> >The reason for the change of prop was two fold, it was felt that the
-> lack
-> > >of
-> > >-> >performance may be due in part to the prop not being too efficient
-> for
-> > >the
-> > >-> >job given the assumed marginal power available. The second reason
-> had to
-> > >do
-> > >-> >with alterations required to fit to my new cowling, but this may
have
-> > >been
-> > >-> >overcome now.
-> > >-> >
-> > >-> >It really comes down to the expensive of changing the pistons for
the
-> > >higher
-> > >-> >hp. Reading your account of flying the 118hp makes me want to do it
-> even
-> > >-> >more! I do like the idea of having a bit in reserve for when
needed.
-> > >-> >
-> > >-> >What I did not want to do was to buy a new sensenich prop at 48
pitch
-> > >only to
-> > >-> >find that I created problems elsewhere and should have done
something
-> > >-> >differently at this stage.
-> > >-> >
-> > >-> >Regards,
-> > >-> >
-> > >-> >Bob
-> > >-> >
-> > >-> >On 4/29/2003 11:54 PM,
APAT@ISTAR.CA wrote to MURPHY-REBEL:
-> > >-> >
-> > >-> >-> From <
apat@istar.ca> Sun, 27 Apr 2003 19:02:45 -0800 remote from
-> > >dcsol.com
-> > >-> >-> Received: by dcsol.com (Wildcat! SMTP Router v5.6.450.61)
-> > >-> >-> for
murphy-rebel@dcsol.com; Sun, 27 Apr 2003
-> 19:02:45 -0800
-> > >-> >-> Received: from nasc-out-1.nasc.inter.net ([203.176.60.253])
-> > >-> >EHLO=app6.nasc.inter.net
-> > >-> >-> by dcsol.com (Wildcat! SMTP v5.6.450.61) with SMTP
-> > >-> >-> id 164454453; Sun, 27 Apr 2003 19:02:44 -0800
-> > >-> >-> Received: from 2cust32.tnt23.toronto.on.da.uu.net
([64.10.100.32])
-> > >-> >-> by app6.nasc.inter.net with smtp (Exim 3.34 #1)
-> > >-> >-> id 199yup-0001IN-00
-> > >-> >-> for
murphy-rebel@dcsol.com; Sun, 27 Apr 2003 23:02:52 -0400
-> > >-> >-> X-Sender:
crs1188@pop.ca.inter.net
-> > >-> >-> X-Mailer: Windows Eudora Light Version 1.5.2
-> > >-> >-> X-Orig-Mime-Version: 1.0
-> > >-> >-> X-Orig-Content-Type: text/plain; charset="us-ascii"
-> > >-> >-> To: <
murphy-rebel@dcsol.com>
-> > >-> >-> From: Bob Patterson <
apat@istar.ca>
-> > >-> >-> Subject: Re: lycoming 0-235
-> > >-> >-> Message-Id: <
E199yup-0001IN-00@app6.nasc.inter.net>
-> > >-> >-> Date: Sun, 27 Apr 2003 23:02:52 -0400
-> > >-> >->
-> > >-> >->
-> > >-> >-> Hi Bob ! (good name !!! ;-) )
-> > >-> >->
-> > >-> >-> I assume you're dumping the Warp Drive because of the
-> > >-> >-> blade cracking problems .... Going to high-compression pistons
-> > >-> >-> will really aggravate this problem, so the W-D is out !!
-> > >-> >->
-> > >-> >-> 72 x 48 doesn't sound tooooo fine - you should still get
-> > >-> >-> about 90 - 95 mph. I never saw more than 95 cruise with my
-> O-235-C2C
-> > >-> >-> (100 hp - on a GOOD day !), and it dragged a pair of 1500 Amphibs
-> > >-> >-> right across the country ! You shouldn't have any problem
-> getting
-> > >-> >-> a Rebel out of 1,100 feet of grass, with clear approaches,
-> > >-> >-> as long as you're not heavily loaded. The fat DICO or Carlyle
-> 800-6
-> > >-> >-> tires from Murphy really help on soft ground ...
-> > >-> >->
-> > >-> >-> I suggest just trying the prop - it can always be
-> re-pitched
-> > >-> >-> if needed. If the engine's running good, and you like to run
-> > >-> >-> mogas, by all means, don't change it..... save the money for
-> > >-> >-> FLYING !!!! ;-) :-)
-> > >-> >->
-> > >-> >-> I have flown a Rebel with the 118 Hp Lycoming O-235-L2C,
-> > >-> >-> metal prop, and it was great - solid 110 mph cruise, and good
-> climb.
-> > >-> >-> MUCH better than my old C2C, rated at 108 hp.....
-> > >-> >->
-> > >-> >-> I second Ralph's opinion - the Elite nosewheel would
-> > >-> >-> not be good on rough or soft fields. (Curious why you ask ???)
-> > >-> >->
-> > >-> >-> .....bobp
-> > >-> >->
-> > >->
-> >-> -------------------------------------orig.-----------------------------
-> > >-> >-> At 11:17 AM 4/27/03 -0800, you wrote:
-> > >-> >-> >I have a lyc 0-235 derated to 105hp turning a 68" 3 bladed warp
-> > >drive. I
-> > >-> >am
-> > >-> >-> >looking at changing to a sensenich 72-ck-0-48 (as discussed with
-> > >-> >sensenich.
-> > >-> >-> >My problem is that although this prop may get me out of the
small
-> > >field
-> > >-> >-> >(390yds) it wont give me much cruise speed. Being rated for
105hp
-> at
-> > >-> >2400rpm
-> > >-> >-> >does not leave much room. I am comtemplating having the engine
-> re-
-> > >rated
-> > >-> >back
-> > >-> >-> >to 118hp but am getting confused as to the benefits of doing
this
-> or
-> > >-> >changing
-> > >-> >-> >the prop??? Any advice welcomed. The engine only has 200hrs
-> smoh so
-> > >I
-> > >-> >am
-> > >-> >-> >somewhat reluctant to change it.
-> > >-> >-> >
-> > >-> >-> >
-> > >-> >-> >Regards,
-> > >-> >-> >
-> > >-> >-> >Bob
-> > >-> >-> >
-> > >-> >-> >
-> > >-> >->
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