Today's Message Index:
----------------------
1. 01:35 AM - Re: Re: Problem solved. Rough running cured with carb heater (joeing701@simnet.is)
2. 01:49 AM - Re: Losing rpm on takeoff (dave)
3. 02:33 AM - Re: Losing rpm on takeoff (Dave G)
4. 02:44 AM - Re: Losing rpm on takeoff (David Joyce)
5. 04:22 AM - Re: Re: Problem solved. Rough running cured with carb heater (Gordon)
6. 05:00 AM - Re: Losing rpm on takeoff (lucien)
7. 05:14 AM - Re: Losing rpm on takeoff (lucien)
8. 05:34 AM - Re: Losing rpm on takeoff (Catz631@aol.com)
9. 06:20 AM - Re: Losing rpm on takeoff (Thom Riddle)
10. 06:26 AM - Re: Losing rpm on takeoff (lucien)
11. 06:57 AM - Re: Problem solved. Rough running cured with carb heater (Roger Lee)
12. 08:20 AM - Re: Problem solved. Rough running cured with carb heater (dashwood)
13. 08:24 AM - Re: Losing rpm on takeoff (Guy Buchanan)
14. 08:39 AM - Re: Re: Losing rpm on takeoff (Richard Girard)
15. 08:55 AM - Re: Losing rpm on takeoff (Thom Riddle)
16. 09:25 AM - Re: Re: Problem solved. Rough running cured with carb heater (=?ISO-8859-1?Q?J=F3hann_J=F3hannsson?=)
17. 10:06 AM - Re: Re: Losing rpm on takeoff (FLYaDIVE)
18. 10:21 AM - Hard Starting tips (Roger Lee)
19. 10:36 AM - Re: Hard Starting tips (Roger Lee)
20. 10:39 AM - Re: Hard Starting tips (Roger Lee)
21. 10:58 AM - Re: Hard Starting tips (Roger Lee)
22. 11:01 AM - Re: Hard Starting tips (Roger Lee)
23. 01:56 PM - Re: Hard Starting tips (Dave Austin)
24. 04:35 PM - Re: Re: Losing rpm on takeoff (GRAHAM SINGLETON)
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| Subject: | Re: Problem solved. Rough running cured with carb |
heater
Hello Roger.
What my friend did was to drill out the needle jet to richen the mixture in the
mid range.
That tells us that the jet was wrong, i.e. did not work on his engine because of
the colder air entering the carbs. Is this not the correct assumtion? Is there
another solution to the lean condition? As I mentioned in my last post, my
engine in the Zenith 701, does not have this problem because the air entering
my carbs is hotter, no airbox. Is this correct? I know you are the expert, and
would like to hear your thoughts about this problem. If you tell us that this
is not the correct way to solve the rough running at the mid range, what other
method can we use?
With thanks,
Johann G.
----- Upprunalegt skeyti -----
Fr: "Roger Lee" <ssadiver1@yahoo.com>
Til: rotaxengines-list@matronics.com
Sent: Mivikudagur, 1. desember, 2010 00:09:43 GMT +00:00 Monrovia
Efni: RotaxEngines-List: Re: Problem solved. Rough running cured with carb heater
Hi Johann,
Something is wrong some where. I have seen the Rotax 912 run in -20F weather and
never miss a beat. It seems like it has to be the wrong needle, wrong jets,
wrong needle clip position, some thing else in the carbs? You may have put a band-aide
on the problem, but might have not fully solved it?
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321856#321856
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| Subject: | Re: Losing rpm on takeoff |
> I am asking if anyone can help me to understand why a moving aircraft might experience
a lower RPM than one tied to a big heavy thing on the ground as this
strikes me as contrary to my previous understanding. This is the only question
I wish to address at this point. I did not know that propellers slow down when
they are tilted up, I expect this is not what you meant.
Dave - if your tach is too high then you could be falling off the power curve and
to do that you would be doing that around 4800 to 5200 rpm .
eg if tach is reading static 6200 rpm then it actually might be only 5000 -5500?
How was take off performance ? You Iv should be off the ground in under 200 feet
with no wind.
--------
Rotax Dealer, Ontario Canada
http://www.cfisher.com/
http://www.kitfoxflyer.com/
http://rotaxaircraft.com/forum/
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/user/kitfoxflyer
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321893#321893
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| Subject: | Re: Losing rpm on takeoff |
We simply haven't got to the point of beginning any testing regimen, we
are attempting to get past this single issue. A lot of information on
other things is just noise at this point.
The tach will be checked of course, it was accurate on my old engine.
----- Original Message -----
From: Noel Loveys
To: rotaxengines-list@matronics.com
Sent: Tuesday, November 30, 2010 11:12 PM
Subject: RE: RotaxEngines-List: Losing rpm on takeoff
Dave:
Barry is probably right in his description of the testing regimen but
I agree with you about getting back to basics. For me Getting back to
basics means making sure your tach is accurate. I'm willing to bet
dollars to doughnuts that your tachometer is reading way too high. If
it is, thinning the pitch will allow your engine to develop more
torque.... hence more power for takeoff.
No doubt you will be actively working on this so keep us informed.
Noel
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| Subject: | Re: Losing rpm on takeoff |
I have come across the phenomenon of the prop being stalled at low forward
speed but unstalling as the plane gathers speed, with the unstalled prop
offering more resistance and therefore slowing rpm. For some props it is
said to be potentially damaging to run them at full power in a stalled
state.
Regards, David Joyce
----- Original Message -----
From: "Dave G" <occom@ns.sympatico.ca>
Sent: Wednesday, December 01, 2010 10:26 AM
Subject: Re: RotaxEngines-List: Losing rpm on takeoff
We simply haven't got to the point of beginning any testing regimen, we are
attempting to get past this single issue. A lot of information on other
things is just noise at this point.
The tach will be checked of course, it was accurate on my old engine.
----- Original Message -----
From: Noel Loveys
To: rotaxengines-list@matronics.com
Sent: Tuesday, November 30, 2010 11:12 PM
Subject: RE: RotaxEngines-List: Losing rpm on takeoff
Dave:
Barry is probably right in his description of the testing regimen but I
agree with you about getting back to basics. For me Getting back to basics
means making sure your tach is accurate. I'm willing to bet dollars to
doughnuts that your tachometer is reading way too high. If it is, thinning
the pitch will allow your engine to develop more torque.... hence more power
for takeoff.
No doubt you will be actively working on this so keep us informed.
Noel
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| Subject: | Re: Problem solved. Rough running cured with carb |
heater
I tend to agree with Roger. My 701 with a 921uls and airbox runs perfectly
in the summer with temps in the 90s F as well as winter flying (on skis)
here in Vermont where it's often well below 0 F.
Gordon
----- Original Message -----
From: <joeing701@simnet.is>
Sent: Wednesday, December 01, 2010 4:27 AM
Subject: Re: RotaxEngines-List: Re: Problem solved. Rough running cured with
carb heater
> <joeing701@simnet.is>
>
> Hello Roger.
>
> What my friend did was to drill out the needle jet to richen the mixture
> in the mid range.
> That tells us that the jet was wrong, i.e. did not work on his engine
> because of the colder air entering the carbs. Is this not the correct
> assumtion? Is there another solution to the lean condition? As I mentioned
> in my last post, my engine in the Zenith 701, does not have this problem
> because the air entering my carbs is hotter, no airbox. Is this correct? I
> know you are the expert, and would like to hear your thoughts about this
> problem. If you tell us that this is not the correct way to solve the
> rough running at the mid range, what other method can we use?
>
> With thanks,
> Johann G.
>
>
> ----- Upprunalegt skeyti -----
> Fr: "Roger Lee" <ssadiver1@yahoo.com>
> Til: rotaxengines-list@matronics.com
> Sent: Mivikudagur, 1. desember, 2010 00:09:43 GMT +00:00 Monrovia
> Efni: RotaxEngines-List: Re: Problem solved. Rough running cured with carb
> heater
>
>
> Hi Johann,
>
> Something is wrong some where. I have seen the Rotax 912 run in -20F
> weather and never miss a beat. It seems like it has to be the wrong
> needle, wrong jets, wrong needle clip position, some thing else in the
> carbs? You may have put a band-aide on the problem, but might have not
> fully solved it?
>
> --------
> Roger Lee
> Tucson, Az.
> Light Sport Repairman - Maintenance Rated
> Rotax Repair Center
> Home 520-574-1080 TRY HOME FIRST
> Cell 520-349-7056
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=321856#321856
>
>
>
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| Subject: | Re: Losing rpm on takeoff |
Float Flyr wrote:
>
> I am asking if anyone can help me to understand why a moving aircraft might experience
a lower RPM than one tied to a big heavy thing on the ground as this
strikes me as contrary to my previous understanding. This is the only question
I wish to address at this point. I did not know that propellers slow down when
they are tilted up, I expect this is not what you meant.
>
> ---
Like I said, this is a difference in design of the taper tip WD over a conventional
prop, so you can't really use the same methods to set the initial pitch.
No, you're not imagining anything, the taper tip will spin up faster with the plane
tied to a stick than when accelerating down the runway where it'll actually
load up and slow down. The static load is unreliable because the tips are stalled,
so it' s almost useless to try to set a particular static RPM.
What I did on mine to set the intial pitch was to pitch for the right rpm's on
takeoff/climb. This required a few high speed taxis to confirm the engine was
turning the right rpm (about 5300 to start with) once I got to takeoff speed.
Then, once I got it to where I wasn't dangerously overloaded or underloaded to
actually fly the plane, I went up and verified rpms in flight. On mine (68" 3
blade on a 912ULS, titan tornado) I settled on around 5400 rpm at Vy (about 65mph).
The interesting thing was the rpm would hardly vary from 5400 rpm all the
way up to about 80mph! That's the constant speed -ish action of the taper tip
- it doesn't "unwind" as much as a conventional prop.
Unfortunately I had to go to a different prop because of an incurable harmonic
vibration problem with my particular plane, but while I did have the WD on it
the performance was absolutely spectacular, especially at higher speeds.
So that'd be my suggestion as to how to proceed at this point - get a good rpm
at takeoff speeds so you can actually go fly the plane around. Then fine-adjust
the pitch from there.
LS
--------
LS
Titan II SS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321901#321901
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| Subject: | Re: Losing rpm on takeoff |
occom wrote:
> Thanks Lucien, this sounds quite close to what I am experiencing. It is
> indeed a taper tip, my previous was a GSC which behaved much differently.
>
>
> ---
Right, the GSC is a more conventional prop, with a more constant blade AOA as you
go out to the ends. So most if not all of the blade stalls at the same AOA.
The powerfin I had to replace my WD with is a conventional design too so the static
RPM tends to be a reliable measure. It also spins up and unloads in the expected
way as the airflow through the prop disk increases.
Nothing can outclimb my powerfin but the WD taper tip has by far the best performance
over the widest speed range I've ever seen on a prop. So if yours is a
faster plane, you won't ever want to fly anything else once you get the pitch
set right.
It's particularly good for a 2-stroke on a faster plane since it provides more
of a constant load on the engine which is what you need for a steady EGT....
LS
--------
LS
Titan II SS
Read this topic online here:
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| Subject: | Re: Losing rpm on takeoff |
>> This will for sure be the case if it's a taper tip prop (dont know
about the square
tip). The way it works is the tips are essentially stalled at static
airflows,
but then they unstall as the airflow picks up through the prop disk.
This happens for quite a range of airspeeds, which is how the prop manages
to work
almost like a constant-speed and gives a very consistent load over a wide
range of speeds.
So the static rpm almost doesn't tell you anything. The first time I ran a
taper
tip on my 912 I didn't understand how it worked. I added pitch until I got
about
5200 static, but when I went out to do a taxi test, the rpm dropped and
dropped
and dropped as I picked up speed just like the other poster said. By the
time I was at rotate speed (about 60mph or so) I was down to about 4700 rpm!
So basically you have to pitch for correct rpms when moving (i.e. just
bumping
up against redline at max level speed and wide open, or for desired rpm at
your
desired airspeed, i.e. 6300 or so for the 582).
The taper tip has a really wide speed range so you can get it just about
spot on
by pitching for redline at max. level and you're pretty much done at that
point.
LS <<
Interesting LS ,my Warp taper tip has never done that in the 2 years it has
been on my aircraft. I get 5200 WOT on take off roll and on climbout it
accelerates to about 5400 rpm on my 80 hp 912.
I am now using a Kiev and it too never drops. It,however stays at 5200 rpm
thru take off and climb. I have been watching these numbers very closely
comparing the two propellers.I am staying with the Kiev as it is lighter and
much,much smoother.
Dick Maddux
912 UL
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| Subject: | Re: Losing rpm on takeoff |
Recently, when I was doing a pre-purchase inspection on a Sonex with Jabiru 2200
engine, the static rpm at WOT on the ground was 3250, just 50 rpm short of redline
and max continuous rpm limit of 3300. During take-off the rpm drops to
3,000 rpm at full throttle climb at Vy. This is with a Sensenich wood prop (fixed
pitch). That is 250 rpm drop on a 3300 max rpm engine and this is perfectly
normal. Within a few rpm, that is the same thing I get on my Kolb Slingshot
with almost identical engine, but with a Tennessee wood prop.
On a 6300 rpm engine, a 500 rpm drop sounds about right.
Perhaps your test pilot does not have a complete grasp of what normal fixed pitch
prop/rpm behavior is during various flight regimes.
--------
Thom Riddle
Buffalo, NY (9G0)
Kolb Slingshot SS-021
Jabiru 2200A #1574
Tennessee Prop 64x32
Everyone is entitled to his own opinion, but not his own facts.
Daniel Patrick Moynihan
Read this topic online here:
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| Subject: | Re: Losing rpm on takeoff |
Dick Maddux wrote:
>
> Interesting LS ,my Warp taper tip has never done that in the 2 years it has
been on my aircraft. I get 5200 WOT on take off roll and on climbout it accelerates
to about 5400 rpm on my 80 hp 912.
> I am now using a Kiev and it too never drops. It,however stays at 5200 rpm
thru take off and climb. I have been watching these numbers very closely comparing
the two propellers.I am staying with the Kiev as it islighter and much,much
smoother.
>
No idea.... On my tornado, tho, it was very noticeable especially at the beginning
when I had it overpropped.
Once I got it dialed in, tho, it was a lot more steady. When I put the coals to
it it'd go up to about 5300 and stay there until I was off the ground and climbing
at Vy. It would creep up about 50 to maybe 100rpm if I sped up to about
80mph. It went up to about 5550 or thereabouts at WOT, straight and level (about
110mph!).
My powerfin, OTOH, really lugs the motor when starting my TO roll (I can barely
get 4800 rpm) but unloads a bunch as I approach TO speed. At 65mph at its current
setting I get about 5180, if I speed up to 80 I bump up to about 5400 rpm.
It'll exceed redline in level flight the way I have it set right now (estimated,
of course, never actually tested that ;)). I live at 7000' MSL so I need
all the climb I can get.
Interestingly, looking at the logbooks, the actual pitch I've settled on with the
powerfin is virtually identical to the pitch I used with the WD (about 14 degrees
at the tips). Yet, the WD had zounds more speed range and a much more constant-speed
prop behavior. The PF is much narrower, tho it generates more thrust
than the WD.
So dunno.....
LS
--------
LS
Titan II SS
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| Subject: | Re: Problem solved. Rough running cured with carb heater |
Hi Johann,
My question would be, Unless someone has overhauled those carbs at one time and
put the wrong kit in or moved the clip on the needle you should not have had
any issues from the Rotax stock carb setup with in the OAT you posted at 40F?
If you are having a problem and those carbs have never been touched then I would
have pulled those carbs and done a fuel system flow check, a fuel pressure
check and dis-assembled the carbs for a good cleaning. Even the the smallest piece
of dirt in a carb can cause the issue you describe. I would like to know
if the clip on the needle was in the third slot from the top? If it was strictly
a mid range problem you could have moved the clip down to the forth slot, but
this should not have been necessary. You still have the same problem with what
you did, but are masking or bypassing it by allowing more fuel in by drilling
the jet. You should also buy the proper jets and not drill them.
I would quit considering the air temp of 40F a major factor and start looking for
a fuel flow issue.
My slant on this is you still have the original problem, just covered up now. It
could show up later and not in a way you want it to.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321914#321914
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| Subject: | Re: Problem solved. Rough running cured with carb heater |
my 2 cents. i run a 912 with 450 hr on it. the operational range is 40deg C to
-20C . the starting procedures change and the oil grade, preheat.changes but
nothing else is done to the carbs. in below 0C the oil rad is taped off and the
water had has a 60 % blocking out plate. the carbs were disassembled by a rotax
tec at 400hr and no wear or problems found.i do not have carb heat. with
2 cone K&N filters. i believe the airflow inside the cowl is in along the bottom
through the oil and water rads. then back and up and down past the muffler.
some warmed air is going up to the carbs just above muffler then forward along
the top of engine and out the hole around prop . i believe there is a low pressure
area just aft of the spinner and hub. I had a bad oil leak at the rad
connection and this is the oil trail pattern that manifested.
point is when set properly this engine runs great in many varied conditions.
--------
Ross Aalexander: CH701 driver 912ul 450tt
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| Subject: | Re: Losing rpm on takeoff |
On 11/30/2010 4:13 PM, FLYaDIVE wrote:
> Your data does not make sense. If you were over pitch and started to
> roll you would be unloading your prop and the RPM would Go UP.
> ANYTIME you start your take off roll the RPM goes UP. If not....
> Then something else is wrong.
> Even if you were under pitched there would be a increase in RPM ...
> Not as much as if you had the correct pitch or over pitched... But it
> would still go UP.
Barry,
I never found an analytical solution, but if the prop's stalled at
static run-up due to too high angle of attack it will then "slip",
unloaded, until the angle attack reduces enough for it to un-stall.
Increasing airspeed reduces the angle of attack on the prop, hence my
deduction that my prop un-stalled, loaded up, and pulled the RPM's down
on the 582. Yes it's all theoretical, but I wasn't able to come up with
a better excuse, particularly after reducing the pitch solved the
problem entirely.
Guy Buchanan
Kitfox IV-1200 / 582-C / Warp 3cs / 500 hrs.
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| Subject: | Re: Losing rpm on takeoff |
Thom, I'm aware of prop stalling, you could actually hear the engine slow
down on my friend's IO-360 powered LongEZ, but as I recall he was running a
Catto prop with 93" of pitch and blades wide enough to provide shade to
several children and small adults. Standing still it truly looked like an
"airscrew".:-}
I do not get the effect everyone is referring to with my 582 and 3 blade,
square tip, straight blade Warp Drive prop at all. By the numbers Dave
supplied for static RPM I should since I set my prop for 5900 RPM static an
d
it kisses 6000 once I'm rolling. Climbing at 50 mph, it stays on 6000 until
I change to my cruise climb setting of 5600. I have to reduce throttle to
maintain that cruise RPM once I level off so I don't see where the prop is
suddenly getting more "bite".
The hard part, with a Kolb Mk IIIC and its crappy aerodynamics is knowing
what part all that blockage from the fuselage, wing, bad gap seals, and
engine standing tall and proud have to do with it. Since my engine is set a
s
low as I can get it with a prop tip / boom clearance of only about an inch,
there's also the phenomenon of how much efficiency I gain or loose by havin
g
the wing direct air into the prop from its underside versus what is lost or
gained by the turbulent air coming over the top. I do know that if I get to
o
aggressive when climbing out that I can hear when the prop begins to
cavitate.
I did go out last night and check the prop pitch to send to Dave for
comparison with his. 14 degrees 20 minutes according to the WD protractor
(20d30m down side, 8d10m up) which translates to just a smidge more than 50
"
pitch.
Rick Girard
On Wed, Dec 1, 2010 at 8:18 AM, Thom Riddle <riddletr@gmail.com> wrote:
m
> >
>
> Recently, when I was doing a pre-purchase inspection on a Sonex with Jabi
ru
> 2200 engine, the static rpm at WOT on the ground was 3250, just 50 rpm sh
ort
> of redline and max continuous rpm limit of 3300. During take-off the rpm
> drops to 3,000 rpm at full throttle climb at Vy. This is with a Sensenich
> wood prop (fixed pitch). That is 250 rpm drop on a 3300 max rpm engine an
d
> this is perfectly normal. Within a few rpm, that is the same thing I get
on
> my Kolb Slingshot with almost identical engine, but with a Tennessee wood
> prop.
>
> On a 6300 rpm engine, a 500 rpm drop sounds about right.
>
> Perhaps your test pilot does not have a complete grasp of what normal fix
ed
> pitch prop/rpm behavior is during various flight regimes.
>
> --------
> Thom Riddle
> Buffalo, NY (9G0)
> Kolb Slingshot SS-021
> Jabiru 2200A #1574
> Tennessee Prop 64x32
>
>
> =93Everyone is entitled to his own opinion, but not his own facts.=94
> Daniel Patrick Moynihan
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=321912#321912
>
>
===========
===========
===========
===========
>
>
--
Zulu Delta
Kolb Mk IIIC
582 Gray head
4.00 C gearbox
3 blade WD
Thanks, Homer GBYM
It is not bigotry to be certain we are right; but it is bigotry to be unabl
e
to imagine how we might possibly have gone wrong.
- G.K. Chesterton
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| Subject: | Re: Losing rpm on takeoff |
Rick,
What you describe seems to be common with the Warp Drive props based on what I've
heard from others with a WD prop. I've never owned one so don't have personal
experience with them. On all the airplanes I've owned with fixed pitch props,
what I described is the norm. No idea why the the WD behaves differently but
it sounds like a very good thing... almost like the performance advantage of
a constant speed prop allowing full power RPM during takeoff and climb without
limiting cruise speed. For climb performance limited aircraft in high density
altitudes, that could be a real advantage compared to other props.
--------
Thom Riddle
Buffalo, NY (9G0)
Kolb Slingshot SS-021
Jabiru 2200A #1574
Tennessee Prop 64x32
Everyone is entitled to his own opinion, but not his own facts.
Daniel Patrick Moynihan
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321931#321931
Message 16
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| Subject: | Re: Problem solved. Rough running cured with carb |
heater
Thank you Roger for the input.
The carbs have the stock setup jets, all according to Rotax. They have
been cleaned many times, and the needle clip is in the bottom slot for
richest mixture. Everything is new in the carbs. Fuel system has been
cleaned from the tanks to the carbs. New fuel filter. Air cleaner has
been cleaned with K&N cleaning kit according to the manual. The air
temps have gone down to 20F up to 40F during the test. The enricher
does not seem to fix the problem, but just the carb heat. My friend
has ordered new carbs and will try those in a few days. I will keep
you posted.
Thanks again,
Johann G.
On 1.12.2010, at 14:54, Roger Lee wrote:
> >
>
> Hi Johann,
>
> My question would be, Unless someone has overhauled those carbs at
> one time and put the wrong kit in or moved the clip on the needle
> you should not have had any issues from the Rotax stock carb setup
> with in the OAT you posted at 40F? If you are having a problem and
> those carbs have never been touched then I would have pulled those
> carbs and done a fuel system flow check, a fuel pressure check and
> dis-assembled the carbs for a good cleaning. Even the the smallest
> piece of dirt in a carb can cause the issue you describe. I would
> like to know if the clip on the needle was in the third slot from
> the top? If it was strictly a mid range problem you could have moved
> the clip down to the forth slot, but this should not have been
> necessary. You still have the same problem with what you did, but
> are masking or bypassing it by allowing more fuel in by drilling the
> jet. You should also buy the proper jets and not drill them.
> I would quit considering the air temp of 40F a major factor and
> start looking for a fuel flow issue.
>
> My slant on this is you still have the original problem, just
> covered up now. It could show up later and not in a way you want it
> to.
>
> --------
> Roger Lee
> Tucson, Az.
> Light Sport Repairman - Maintenance Rated
> Rotax Repair Center
> Home 520-574-1080 TRY HOME FIRST
> Cell 520-349-7056
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=321914#321914
>
>
Message 17
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| Subject: | Re: Losing rpm on takeoff |
Thom, Rick & Gaggle:
Many years ago, back around 1975 I worked on a prop for the Gossamer and
Gossamer Albatross. Remember those planes? It was the first man powered
plane to fly a closed figure eight course. The prop was made from FOAM wit
h
a very thin fiberglass (3/4 oz cloth) coating. It also had a 25 degree
washout. We did not talk inches of pitch back then. At high speed the
pitch would flatten and after the plane gained altitude
and stabilized flight the prop would un-load, prop slowed down which let th
e
pitch increase. From this information I would guess-ta-mate that the same
is happening to the Warp Drive Prop. There is a small flexing in the twist
that changes with RPM.
Barry
On Wed, Dec 1, 2010 at 11:53 AM, Thom Riddle <riddletr@gmail.com> wrote:
m
> >
>
> Rick,
>
> What you describe seems to be common with the Warp Drive props based on
> what I've heard from others with a WD prop. I've never owned one so don't
> have personal experience with them. On all the airplanes I've owned with
> fixed pitch props, what I described is the norm. No idea why the the WD
> behaves differently but it sounds like a very good thing... almost like t
he
> performance advantage of a constant speed prop allowing full power RPM
> during takeoff and climb without limiting cruise speed. For climb
> performance limited aircraft in high density altitudes, that could be a r
eal
> advantage compared to other props.
>
> --------
> Thom Riddle
> Buffalo, NY (9G0)
> Kolb Slingshot SS-021
> Jabiru 2200A #1574
> Tennessee Prop 64x32
>
>
> =93Everyone is entitled to his own opinion, but not his own facts.=94
> Daniel Patrick Moynihan
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=321931#321931
>
>
===========
===========
===========
===========
>
>
Message 18
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| Subject: | Hard Starting tips |
FYI
My 912S does not start, whats going on?
All of the Rotax 9 series engines are known to start quickly and readily. (Many
people report their engines start within 1 revolution of the crank).
The 912S/ULS is a high compression engine and that can cause the engine to move
(shake) in the engine mounts if the engine mount is not strong enough. Many 912S
installations are designed for the lower compression 912UL engine and are
not beefed up when the 912S is installed. This is the root cause of many 912S
starting/operating issues and must be cured before proceeding with any other actions.
Here are the factors related to hard starting:
Engine shaking during the start cycle. This causes the fuel in the carbs to froth
and spill into the venture and/or the vent lines. With the fuel system disrupted
the engine cannot start.
Carb shaking; even with a proper engine mount you can still have carb shaking
problems. The best solution is installing the Rotax 912S airbox as it rigidly
fixes the carbs, preventing most shaking. A side benefit is that SB-912-030 (inspection
of the carb flanges) is not applicable with the airbox installed.
Loose gearbox; If the gearbox is allowed to lose its spring pressure (see Gearbox
related FACs) the engine will not want to start as the prop will be fighting
the compression strokes. Basically the engine gets into a cycle of kicking
back and forth between the compression/ignition pulses and the prop forces hitting
the dogs in the gearbox. Remove and send your gearbox for re-shimming of
the springs.
Tips for hard starting in cold weather:
Increase starting jet size to allow more fuel. (SI-03-98) It may be necessary
to switch back to small jets in warmer weather.
Modify choke rotary disc (SI-03-98)
Reduce spark plug gap to minimum.
Make sure you have a good battery. Does jump starting help? If it does you may
want to change batteries.
Battery wire size, connections and grounds. Check for voltage drop between battery
and starter.
Preheat is always a good idea. Avoid rapid methods that can damage your aircraft.
Check to see if the choke is full on and both are equal. Proper set up of the
cables is critical.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321939#321939
Message 19
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| Subject: | Re: Hard Starting tips |
FYI
Coolant flow route
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321941#321941
Attachments:
http://forums.matronics.com//files/coolant_flow_route_116.pdf
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| Subject: | Re: Hard Starting tips |
FYI
Oil Flow Route
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321942#321942
Attachments:
http://forums.matronics.com//files/oil_flow_route_672.pdf
Message 21
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| Subject: | Re: Hard Starting tips |
FYI
Here is something to help you maintain your high tech engine and keep your re-sale
value in check.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321946#321946
Attachments:
http://forums.matronics.com//files/maintenance_schedules_177.pdf
Message 22
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| Subject: | Re: Hard Starting tips |
Here is the Rotax Maint. 912 inspection check list. Use it, it will keep you safe
and keep your re-sale value up.
--------
Roger Lee
Tucson, Az.
Light Sport Repairman - Maintenance Rated
Rotax Repair Center
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=321947#321947
Attachments:
http://forums.matronics.com//files/inspection_check_list_210.pdf
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| Subject: | Re: Hard Starting tips |
I'll add on item to Roger's list. Make absolutely sure that the throttles are
fully closed.
Dave Austin
Message 24
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| Subject: | Re: Losing rpm on takeoff |
Barry=0AGossamer Condor and Albatross were fantastic but I don't think the
Warp drive =0Ahas any flex, it's far too stiff. I think it's the stall char
acteristics of the =0Asection which was an odl RAF section I think. That sh
arp leading edge has =0Asomething to do with it I suspect. btw Paul McCread
y was a genius!=0AGraham=0A=0A=0A=0A=0A________________________________=0AF
rom: FLYaDIVE <flyadive@gmail.com>=0ATo: rotaxengines-list@matronics.com=0A
Sent: Wednesday, 1 December, 2010 18:03:49=0ASubject: Re: RotaxEngines-List
: Re: Losing rpm on takeoff=0A=0AThom, Rick & Gaggle:=0A=0AMany years ago,
back around 1975 I worked on a prop for the Gossamer and =0AGossamer Albatr
oss. Remember those planes? It was the first man powered plane =0Ato fly
a closed figure eight course. The prop was made from FOAM with a very =0At
hin fiberglass (3/4 oz cloth) coating. It also had a 25 degree washout. W
e =0Adid not talk inches of pitch back then. At high speed the pitch would
flatten =0Aand after the plane gained altitude and stabilized flight the p
rop would =0Aun-load, prop slowed down which let the pitch increase. From
this information I =0Awould guess-ta-mate that the same is happening to the
Warp Drive Prop. There is =0Aa small flexing in the twist that changes wi
th RPM.=0A=0ABarry=0A=0A=0A=0A=0AOn Wed, Dec 1, 2010 at 11:53 AM, Thom Ridd
le <riddletr@gmail.com> wrote:=0A=0A--> RotaxEngines-List message posted by
: "Thom Riddle" <riddletr@gmail.com>=0A>=0A>Rick,=0A>=0A>What you describe
seems to be common with the Warp Drive props based on what =0A>I've heard f
rom others with a WD prop. I've never owned one so don't have =0A>personal
experience with them. On all the airplanes I've owned with fixed pitch =0A>
props, what I described is the norm. No idea why the the WD behaves differe
ntly =0A>but it sounds like a very good thing... almost like the performanc
e advantage of =0A>a constant speed prop allowing full power RPM during tak
eoff and climb without =0A>limiting cruise speed. For climb performance lim
ited aircraft in high density =0A>altitudes, that could be a real advantage
compared to other props.=0A>=0A>=0A>--------=0A>Thom Riddle=0A>Buffalo, NY
(9G0)=0A>Kolb Slingshot SS-021=0A>Jabiru 2200A #1574=0A>Tennessee Prop 64x
32=0A>=0A>=0A>=9CEveryone is entitled to his own opinion, but not his
own facts.=9D=0A>Daniel Patrick Moynihan=0A>=0A>=0A>=0A>=0A>Read thi
s topic online here:=0A>=0A>http://forums.matronics.com/viewtopic.php?p=3
21931#321931=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=0A>=========
===0A>="_blank">www.aeroelectric.com=0A>ooks.com" target="_blank">w
ww.buildersbooks.com=0A>et="_blank">www.homebuilthelp.com=0A>="_blank">
http://www.matronics.com/contribution=0A>le, List Admin.=0A>=====
=======0A>-List" target="_blank">http://www.matronics.com/Nav
igator?RotaxEngines-List=0A>============0A>http://for
ums.matronics.com=0A>============0A>=0A>=0A>=0A>=0A
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