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dave
Joined: 22 Sep 2006
Posts: 1382
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 Posted: Sat Mar 16, 2013 8:02 am Post subject: Warpdrive ! Scotty! |
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Numbers are not 100 % correct on 2nd
chart
the litre to gal.hour conversion alone does not look correct
Dave
[quote] ---
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7suds(at)Chartermi.net
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| Posted: Sat Mar 16, 2013 8:04 am Post subject: Warpdrive ! Scotty! |
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Sacha,
WOW, that is great information, did not expect all the leg work but I thank you for the research and the post. I am not currently running a MAP gauge but it looks like I will be putting one in. I’ll keep the group posted, currently have the plane down and gutted for annual.
Lloyd C
Fox5 912ul IVO IFA
Northern Mi.
[img]cid:image003.png(at)01CE2236.0F964DD0[/img]
From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Sacha
Sent: Saturday, March 16, 2013 7:41 AM
To: kitfox-list(at)matronics.com
Subject: RE: Warpdrive ! Scotty!
Reposting with pics rather than tables! Sorry about that!
Hi Jim, Lowell, Stan et al,
I’ve been learning a lot in this conversation, thanks for your inputs. Today I woke up early and decided to go and read up the Rotax documentation.... Here is what I found:
<![if !supportLists]>- <![endif]>Rotax service letter SL-912-016 / SL-914-014 (search for the later on ROAN as if you search for the former it does not appear for some reason) is entitled “Essential Information Regarding Engine behavior, Performance and Manifold Pressure Data for Rotax 912 and 914 Series”. Section 3.1.4 specifies that a MAP gauge *must* be fitted when using an in flight adjustable prop. Presumably so that one does not load the engine excessively with RPM too low.
<![if !supportLists]>- <![endif]>The Operators manual (Ed 3, Rev. 0, September 01/2012) has a table on page 5-3 of recommended RPM/MAP settings for the 912 engines with variable pitch propellers which I’ve reproduced here:
[img]cid:image001.png(at)01CE2231.7E28FB80[/img]
* It looks like the MAP of 26.3 for 4300 RPM is wrong in the above table. If I check the graph in Fig. 2 on page 5-2, for 4300 RPM I read off 24.3, so I guess there’s a misprint there. The other numbers look ok and appear to make sense.
<![if !supportLists]>- <![endif]>In my case, I don’t have space for a MAP gauge on my panel, but I already have a Floscan fuel monitor/gauge. I’m wondering if that could be substituted for the MAP gauge? After all, fuel burn tells me how much energy I’m feeding into the engine, so it should be very closely correlated to power developed. And my fuel return line goes back to the gascolator (downstream of the fuel flow sensor), so the fuel slow sensor should be measuring net fuel consumption. I’m just not sure how accurate/responsive it is to changes. Anyway, I’ve used the fuel consumption (Fig 2 on page 5-2) of the Operators manual and derived the following table. Here, I’ve reported the power requirement of the propeller rather than the max engine output, since the former is what is almost perfectly proportional to fuel flow, as can be verified by the fact that the last column (giving fuel consumption in L/h per HP developed) is almost constant. Data is from pages 5-2 & 5-3 of the operator manual (corrected for the misprint I mentioned above)
[img]cid:image002.png(at)01CE2231.7E28FB80[/img]
The fuel consumption numbers appear to make sense and to be similar to what e.g. Stan was reporting.
Sacha
On Mar 16, 2013, at 2:23, James Shumaker <jimshumaker(at)sbcglobal.net (jimshumaker(at)sbcglobal.net)> wrote:
[quote]
It should be no problem to run that way. Rotax reccomends against running the engine at full throttle if less than 5200 rpm can be maintained (as in a climb).
Jim Shumaker
Kitfox III
1100 hours
Rotax 912 ul
Warp drive 3 blade ground adjustable.
From: Lowell Fitt <lcfitt(at)sbcglobal.net (lcfitt(at)sbcglobal.net)>
To: kitfox-list(at)matronics.com (kitfox-list(at)matronics.com)
Sent: Fri, March 15, 2013 9:13:33 AM
Subject: Re: Warpdrive ! Scotty!
I wonder if this would be a good idea without a manifold pressure gauge. It sort of sounds like the no nos about lugging an automobile engine.
Lowell
From: Lloyd & Lorrie Cudnohufsky (7suds(at)Chartermi.net)
Sent: Wednesday, March 13, 2013 6:30 PM
To: kitfox-list(at)matronics.com (kitfox-list(at)matronics.com)
Subject: RE: Warpdrive ! Scotty!
Stan, All,
I either read or heard somewhere that with the IFA prop you can fire wall the engine and trim the prop to 5500 RPM for your max cruise speed, any experience with that theory of operation?
Lloyd
From: owner-kitfox-list-server(at)matronics.com (owner-kitfox-list-server(at)matronics.com) [mailto:owner-kitfox-list-server(at)matronics.com (owner-kitfox-list-server(at)matronics.com)] On Behalf Of Stan Specht
Sent: Monday, March 11, 2013 12:35 AM
To: kitfox-list(at)matronics.com (kitfox-list(at)matronics.com)
Subject: Re: Warpdrive ! Scotty!
LLoyd-
I get about 5400 rpm static run-up with my 70" IVO prop in full take-off/climb pitch. It can easily redline during takeoff, since I do not have any stop washers on the prop. I would not let anyone else fly the aircraft, since it could be easy to over-rev during takeoff. Not sure if I would recommend this situation to anyone else, but I have lots of hours on the a/c and am very used to its abilities. I usually climb out at 60-65 mph ias and 10 deg. flaps with great success. In cruise I set the throttle at about 5500 rpm and bring the rpm to about 5200 rpm with prop pitch. (Anything below about 5200 I begin seeing a slower speed.) I see about 3.7-3.8 gph in this setting for about a true airspeed of 115 mph.( A friend that has flown with me thinks I get closer to 120 mph at this setting.) If I want to burn 4 gph I can get about 120 mph. Not bad on 80 hp.
Stan
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uuccio(at)gmail.com
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| Posted: Sat Mar 16, 2013 8:45 am Post subject: Warpdrive ! Scotty! |
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Dave> Numbers are not 100 % correct on 2nd
Dave> chart
Dave> the litre to gal.hour conversion alone does not look correct
Seems ok to me, am using 3.785 L/US Gal, then having Excel round to the first decimal place. Which number seems wrong?
[quote][b]
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dave
Joined: 22 Sep 2006
Posts: 1382
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| Posted: Sat Mar 16, 2013 10:20 am Post subject: Warpdrive ! Scotty! |
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my mistake --
[quote] ---
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Realtime Kitfox movies to separate the internet chatter from the truth
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