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912UL max and cruise RPM
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john(at)leptron.com
Guest

Posted: Sun Jul 15, 2007 6:32 pm Post subject: 912UL max and cruise RPM

Giovanni,

I use 5800 for take off, and climb. My cruise is almost always 5300 and

gives me 115-118 mph at medium load. If heavy loaded it will drop to 105-110

true.



Model 4 speedster

912ul

Short wing

NSI cap






On the 4 speedster 912UL  what are most using for max and cruise RPM? What

airspeeds are you getting at those RPM on what prop? Thanks



--------

_______________________________________

Giovanni Day

Model 4 speedster 912

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Mon Jul 16, 2007 12:15 pm Post subject: Re: 912UL max and cruise RPM

According to the Rotax 912UL manual, with a variable pitch propeller, 75% power is achieved at 5000rpm and 27.2 in. HG manifold pressure. I gather that they qualify this with the need for a variable pitch prop because it would be hard to hit those exact numbers otherwise. My electric IVO prop comes in handy here. In practice though, 5000rpm and 26 in. Hg manifold pressure gets me as close to Vne as I care to fly in anything but dead calm air.

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

kitfoxmike

Joined: 05 Dec 2006
Posts: 373

Posted: Mon Jul 16, 2007 1:47 pm Post subject: Re: 912UL max and cruise RPM

I run the prop as flat as it will go on take off, with static at 5400 before takeoff.  As I level off I hit the switch until I get 5400 and leave the throttle all the way in.  I leave it there until I go to land.  My speeds going eastbound to Arlington was 103kts ground speed ( about 120 mph)GPS, took me about an hour to get to wenatchee from spokane. On the return I was up to 120kts ground speed GPS, nice tail wind.  When I landed in cle elum I had a nice head wind and floated onto the runway, way cool, winds were 15+, ellensburg was reporting 15 to 30mph. I have the patriot IVO in flight adjust.

Giovanni Day

Joined: 05 Jul 2007
Posts: 43

Posted: Mon Jul 16, 2007 8:41 pm Post subject: Re: 912UL max and cruise RPM

wingnut,



Wow, I must not have enough pitch or something is bad wrong. 5000 only gets me 90mph IAS and GPS. I do not have wheel pants or lift strut fairing or the radiator speed fairing on yet but I cannot imagine it will make 30MPH, assuming you are calling 120mph VNE. I have a 72in 3 bladed  Warpdrive prop. I need a manifold pressure gauge for sure. Wow.

_________________
_______________________________________
Giovanni Day
Model 4 speedster 912

kitfoxfugit(at)yahoo.com
Guest

Posted: Mon Jul 16, 2007 9:46 pm Post subject: 912UL max and cruise RPM

"Giovanni Day" wrote:

On the 4 speedster 912UL  what are most using for max

and cruise RPM?

 What airspeeds are you getting at those RPM on what

prop?



With the Ivoprop (ultralight), for takeoff, I use the

flatter climb pitch preset in the pattern slowing down

for landing, this gives 5800 for a max performance

takeoff (full throttle).  After gaining sufficient

altitude, I blip the pitch to a steeper cruise, which

brings the RPM down to maybe 5200 or so, then screw

the power (throttle) back to 5000 RPM, with the

throttle back about 1.5" at low altitudes, maybe 1" at

higher altitudes.  This gives about 117 mph at a

little less then 5GPH at lower altitudes at full gross

weight.  It will go a little faster solo.



I should expirement more, but this seems to give the

most efficient balance.  I have no MP guage, but if I

change the prop a little either way after setting the

power, it seems to go slower, ie too much pitch or not

enough.  If the air is rough, I back off the power

some to with the same pitch to maybe 4800 RPM or a

little lower to cruise below manoevering speed.  The

engine runs cooler with the Ivoprop than it did with

the GSC, but I have never tried cruising with full

throttle yet, even at high altitude.



I flight plan for the straight distance between

airports using 100 MPH at 5 GPH for 4 hours max,

normally 3 hours, especially where airports with gas

are scarce.  This gives a margin for climbing,

crosswinds, headwinds, dodging storms, zigzagging

through passes, skirting airspace, finding

communications to close the flight plan, etc., with

more than sufficient fuel reserves.



John Allen

KF IV Speedster, 912UL, Ivoprop

O70 in central CA foothills & Sierras

 

Don't pick lemons.

See all the new 2007 cars at Yahoo! Autos.

http://autos.yahoo.com/new_cars.html

kitfoxmike

Joined: 05 Dec 2006
Posts: 373

Posted: Tue Jul 17, 2007 5:14 am Post subject: Re: 912UL max and cruise RPM

I do the same for flight planning, 5gph, and for the same reasons.

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Tue Jul 17, 2007 5:32 am Post subject: Re: 912UL max and cruise RPM

 	  Quote: 	
		  Wow, I must not have enough pitch or something is bad wrong. 5000 only gets me 90mph IAS and GPS. I do not have wheel pants or lift strut fairing or the radiator speed fairing on yet but I cannot imagine it will make 30MPH, assuming you are calling 120mph VNE 	


VNE on the model IV 1200 is 125. Even in dead calm weather, I'm not comfortable flying any closer than 115. If it's even a little little bumpy, I bring that down to 110. That's usually around 26 in Hg  of manifold pressure for me. As you pointed out, you're probably pitched a little flatter then I am in this configuration. Without being able to adjust your pitch in flight, you have to make compromises between climb and cruise. With an 'in flight' adjustable prop, I can have my cake and eat it too .

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

kitfoxmike

Joined: 05 Dec 2006
Posts: 373

Posted: Tue Jul 17, 2007 9:52 am Post subject: Re: 912UL max and cruise RPM

I was asked over the weekend why my fox goes so fast, my reply was, as I was grabbing the wing struts (plastic) must be because they are not glued, as I twisted them up. I said that when in flight they adjust to the center on their own.

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Tue Jul 17, 2007 10:37 am Post subject: Re: 912UL max and cruise RPM

 	  Quote: 	
		  I was asked over the weekend why my fox goes so fast 	


I imagine that running WOT doesn't hurt too.

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

Giovanni Day

Joined: 05 Jul 2007
Posts: 43

Posted: Tue Jul 17, 2007 11:01 am Post subject: Re: 912UL max and cruise RPM

At what RPM are you guys calling WOT?

_________________
_______________________________________
Giovanni Day
Model 4 speedster 912

wingnut

Joined: 11 Jan 2006
Posts: 356

Posted: Tue Jul 17, 2007 12:08 pm Post subject: Re: 912UL max and cruise RPM

 	  Quote: 	
		  At what RPM are you guys calling WOT? 	


WOT = Wide Open Throttle. Meaning your throttle is pushed all the way in. Actual RPM will depend on air speed, prop pitch, density altitude, etc. Relevant to this discussion is the fact that an in flight adjustable prop lets you control your RPM without changing the throttle.

_________________
Luis Rodriguez
Model IV 1200
Rotax 912UL
Flying Weekly
Laurens, SC (34A)

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Jul 17, 2007 12:35 pm Post subject: 912UL max and cruise RPM

WOT isn't an rpm.  It means the throttle is all the way in and the manifold

pressure is close to 14 in Hg.  Rpm will depend on how much bite you have

your prop set for.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Fox5flyer
Guest

Posted: Tue Jul 17, 2007 12:55 pm Post subject: 912UL max and cruise RPM

Noel, shouldn't that actually be up around 28 or 29 inches MP (depending on

variables) when at full throttle?  Perhaps we're talking about different

measurements?

Deke Morisse

N148DM

S5/Soob/CAP

NE Michigan

"The influence of each human being on others in this life is a kind of

immortality."

-- John Quincy Adams



---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Jul 17, 2007 2:26 pm Post subject: 912UL max and cruise RPM

My bad... Too long out of grade school... its around 29.92 in. Hg. and 14.7

psi..  I looked it up this time:-).  Funny thing is it didn't look right

when I wrote it and I changed it.....Sometimes you shouldn't second guess

yourself.



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Don G

Joined: 10 Jan 2006
Posts: 156
Location: Central Illinois

Posted: Tue Jul 17, 2007 5:50 pm Post subject: Re: 912UL max and cruise RPM

Hmmm...This is an interesting thread of info. I should throw my numbers in...even tho they are not near so interesting.



3 blade taper tip 68"warp on a 692lb empty 912 UL speedster.

with me at 185lbs and half fuel or so....

no strut farings ....yet...wheel pants in the shed cause they get in the way.(and the way I land I am afraid I will knock em off!)



wot and 5700 rpms makes 105 mph..all shes got.

5000 rpms makes 90mph. maybe 95

WOT on takeoff makes about 5300



me and a 145 lb passenger...5000 rpms makes 80 to 85mph



I hope to look over some speedsters at OshKosh and see where mine can be improved.

_________________
Don G.
Central Illinois
Kitfox IV Speedster
Luscombe 8A
RV9A

john(at)leptron.com
Guest

Posted: Tue Jul 17, 2007 7:29 pm Post subject: 912UL max and cruise RPM

Don G.

The strut fairings are the biggest and best mod you can make. I tried 4

different fairings until I found the best. That is the stuff that kitfox now

sales ( I think) from no fairings to the new is about 9 mph. The wood

fairing that was used behind the strut is about 3.5 mph. I was scared the

first time I flew with them, the plane used to hit a wall like yours and it

flew past that and changed her sound, weird, but very cool. You now have to

think about how to slow the thing down. My speedster is 720 lbs. And I

licensed it for 1320.



John Oakley

Hmmm...This is an interesting thread of info. I should throw my numbers

in...even tho they are not near so interesting.



3 blade taper tip 68"warp on a 692lb empty 912 UL speedster.

with me at 185lbs and half fuel or so....

no strut farings ....yet...wheel pants in the shed cause they get in the

way.(and the way I land I am afraid I will knock em off!)



wot and 5700 rpms makes 105 mph..all shes got.

5000 rpms makes 90mph. maybe 95

WOT on takeoff makes about 5300



me and a 145 lb passenger...5000 rpms makes 80 to 85mph



I hope to look over some speedsters at OshKosh and see where mine can be

improved.



--------

Don G.

Central Illinois

Kitfox IV Speedster

Luscombe 8A



http://www.geocities.com/dagger369th/my_firefly.htm





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=124497#124497

Giovanni Day

Joined: 05 Jul 2007
Posts: 43

Posted: Tue Jul 17, 2007 9:31 pm Post subject: Re: 912UL max and cruise RPM

Did a little flying ad testing this afternoon. 5000RPM get me 3.7gph burn and 90mph indicated which is very close to ground speed with 0 wind. I had not tried WOT in straight and level. I am able to over rev the motor. I hit 5800 and about 110 mph. I say about because I had to back off to keep from over revving the engine. I think I need to add at least a degree of pitch. I read somewhere that to prolong the engine life of a 912ul one should not rev higher than 5500 even on climb out. I will add the pitch and see what happens. 



I am looking at a set of the PVC strut fairing now.



Keep the good info coming.



Thanks

_________________
_______________________________________
Giovanni Day
Model 4 speedster 912

kitfoxmike

Joined: 05 Dec 2006
Posts: 373

Posted: Wed Jul 18, 2007 5:20 am Post subject: Re: 912UL max and cruise RPM

Now here is my scoop.  I don't let mine run past 5400 rpm.  On climb out I will let it go to 5800, but just briefly, I will set the rpm with the elevator, not the prop.  I want to get it up there so to speak.  If I don't need the elevation, already at 1000agl, then I'm leveling and I'm setting the prop(you know, inflight adjust).  As I level out the rpm's will increase of course, so I put in a little more adjust on the prop, I keep it at 5400rpm.  I keep the throttle all the way in, call it what you want.  If the rpm doesn't go over 5400 rpm you can run it all day like that.  I've talked to a lot of people about this and they say it's OK, and not other pilots either.  Now with my engine 912ul (80) if you have it set at 5400 rpm or 5000 rpm, the ground speed doesn't change, in fact it might loose a little going to  a lower rpm, but it will run smoother.

av8rps(at)tznet.com
Guest

Posted: Wed Jul 18, 2007 6:04 am Post subject: 912UL max and cruise RPM

Giovanni,



I've found with my Kitfox IV-1200 912ul on amphib floats (with an IVO 

inflight adust prop) that it goes the fastest with the throttle wide open 

and the prop set for a 5400-5500 rpm, which is the max continuous horsepower 

for the 912 (all 79 hp!)



Yes, get some of those fairings on your airplane, as I fly 90 mph+ at 5000 

rpm, and I'm on floats with long wings!



I've attached a panel shot to inspire you.  If my long wing kitfox on floats 

can fly this fast on floats, your speedster should definitely go faster...



And here's a pic of my plane in flight.  It's a neat little Kitfox, but it 

can be cleaned up significantly yet.  I have wing strut and horizontal 

stabilizer strut fairings, but nothing on the jury struts, no gap seals, 

poor fit around vertical fin to stab fairing, and no radiator fairing.  Once 

I do all that I expect I will go faster yet!



Paul Seehafer

Kitfox IV-1200 912ul on Aerocet amphibs



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john(at)leptron.com
Guest

Posted: Wed Jul 18, 2007 7:23 am Post subject: 912UL max and cruise RPM

Paul Seehafer

What a great looking fox, now I want to go and find a new set of floats to

go on mine...



John Oakley

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