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Max rpm or?

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I pretty much already know what to expect at various rpm settings given certain conditions in terms of fuel burn. just wanted to know what sort of speed numbers are you getting at various rpm  settings at a given altitude etc .I am trying to optimize my Sting for cruise performance ( it already climbs like crazy ) so I am just curious if it can keep up with ctws which are known to be fast LSAs.

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1 hour ago, WmInce said:

Be advised folks, Andy's CT is a miniture rocket ship. He gets spectacular cruise performance out of it. He leaves me in the dust.

YMMV.

Good luck with the surgery, Andy!

 

It could be that his analog tach is off, and he is turning his engine at a RPM faster that he thinks. There was someone over on SPT that mentioned they had an errant tach.

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59 minutes ago, Tom Baker said:

It could be that his analog tach is off, and he is turning his engine at a RPM faster that he thinks. There was someone over on SPT that mentioned they had an errant tach.

Good point. That may be worth checking.

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I will scare up an optical tach and check it, but I have no reason to doubt it and I suspect it's as correct as any other analog tach.  I get 5050-5100rpm on a WOT takeoff roll, which is right where it should be.  I can hear/feel the chatter in the gearbox start exactly where the yellow arc starts on the tach.

 

Oh, and I did hear "can you slow up a little" from Bill on the way to Page quite a few times, even when my tach was showing 5000-5100rpm...  ;)

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Andy,  I also use 5300 for cruise and it's interesting because this is just where I like to  cruise and isn't arrived at by looking at fuel burn etc.  As you indicate, 5300 just seems to be a sweet spot for my Rotax and gets me to where I'm going at what I feel is a reasonable speed.

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2 hours ago, Runtoeat said:

Andy,  I also use 5300 for cruise and it's interesting because this is just where I like to  cruise and isn't arrived at by looking at fuel burn etc.  As you indicate, 5300 just seems to be a sweet spot for my Rotax and gets me to where I'm going at what I feel is a reasonable speed.

Same here.

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Okay, I checked my tach against an optical prop tach, and it's not reading wrong.  Once the 2.43 gearbox multiplier was applied, here are my numbers:

TACH RPM                     ACTUAL RPM

2000                                2065

3000                                3037

4000                                3994

4500                                4468

5000                                4981

Keep in mind this is an analog tach, so I could not put the RPM exactly on the rpm I wanted; I had to make my best guess for where any rpm number is "exactly".  I could not get significantly higher than 5000rpm in a static runup, so that is where I stopped.  I guess I could check it in flight at higher rpm...

I flew home last evening in dead calm air at 2000ft, at 5200rpm showing 116kt KIAS, 122KTAS, and 119kt GPS ground speed.

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CTLS/CTSW are, I think, the only popular LSAs, equipped with 912 ULS, that can actually approach the advertised 115 Kt KIAS cruise speed in average flying conditions.

In my experience flying Remos, Evektor, Sling and ( the plane I have most experience with ) Sting  - none of these can get much above 105 Kt - I have seen once 112 in  the middle of Winter in my Sting but that's about it.

Yesterday , while flying at 4500 in 95 degree weather , my Sting was struggling to keep 100 kts KIAS at 5300 rpm - that's with a prop pitched for 5650 WOT etc ... 

 

BTW... Andy, I know you are using Garmin Pilot logbook  ... if you go to their Logbook page , in the reports tab at the bottom , what do you see for your average ground speed ? I know GS is highly variable but over 100 hours or so of flying it should reflect your average traveling speed pretty well.

On my Sting I got ( over last 120 hours of flying) :

Average Speed : 111 mph

Average Speed ( Cross Country): 118 mph

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1 hour ago, Warmi said:

BTW... Andy, I know you are using Garmin Pilot logbook  ... if you go to their Logbook page , in the reports tab at the bottom , what do you see for your average ground speed ? I know GS is highly variable but over 100 hours or so of flying it should reflect your average traveling speed pretty well.

On my Sting I got (over last 120 hours of flying) :

Average Speed : 111 mph

Average Speed ( Cross Country): 118 mph

It would be interesting to see those results, for "Andy's little rocket ship." That thing is really slippery . . . to say the least.

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I will report back on that, but it's probably not going to be that high.  At least half my time is meandering around the patch with Cubs and other slow airplanes, at 80-85kt.  But I will look at the report and post the number.

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