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What did you do with your europa this week - 22/12/22
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Area-51

Joined: 03 May 2021
Posts: 376

Posted: Thu Dec 22, 2022 12:50 am Post subject: What did you do with your europa this week - 22/12/22

Flew it again!!!



Check flight for the new AV-30... Love it, it's an awesome bit of kit... Hate the connector on the back, but the gauge itself is awesome... very satisfied with its full sunlight screen brightness.



Today elected for left side mic on the headset, and 1500fpm departure off 23.



Ready to fly it again!!!

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Area-51

Joined: 03 May 2021
Posts: 376

Posted: Sun Dec 25, 2022 5:53 am Post subject: Re: What did you do with your europa this week - 22/12/22

Home alone... 6.00am daily inspection for a 7.00am ramp; no clouds, no wind, no aircraft, no parachutes, no people...  lazy departure off 23 with an early low level turn to the left toward the eastern most point... trundled around the bubble at 75kt for an hour; best 6 litres of hydrocarbon burnt all week!

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peterz(at)zutrasoft.com
Guest

Posted: Sun Dec 25, 2022 3:16 pm Post subject: What did you do with your europa this week - 22/12/22

Careful not to wear and pocket the gearbox dogs with such a lightly loaded prop and low rpm.



Cheers PeteZ

C-GNPZ



 	  Quote: 	
		   On Dec 25, 2022, at 5:30 PM, Area-51 <goldsteinindustrial(at)gmail.com> wrote:

 

 ï»¿

 

 Neither Vy or Vx...

 

 75kt is my loiter speed in calm air; flaps and undercarriage retracted.. setting the rpm at 3900 the aircraft will tootle along happily once trimmed; at 3800rpm it will tootle along at 70kt and is just starting to feel a little bit mushy but still quite stable.

 

 80kt on climb out at 5000rpm returns 1600fpm at 500' AMSL and seems to be the Vy so far... 

 

 Still need to do some upper air work to see what Vx actually is; power on stall is 53kt.

 

 The flaps are about 1deg extended when retracted, and the ailerons are about 1/2deg positive at neutral; so this would affecting the flight characteristics of the wing at various velocities. Not sure if John had intentionally set things up like that; he had a valid reason for all his mods when building.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=509785#509785

Area-51

Joined: 03 May 2021
Posts: 376

Posted: Sun Dec 25, 2022 5:02 pm Post subject: Re: What did you do with your europa this week - 22/12/22

Thanks and noted Peter...



After spending an entire lifetime pulling stuff apart and analysing cause and effect of mechanical component failure i'm totally unconvinced on this argument often presented, simply because the propeller is operating within a state of constant load resistance leaving both the drive and driven gears no opportunity for backlash while in this state; if there was backlash occurring that would be a serious design concern and source of vibration; at my level of experience my ears and bum would let me know as soon as this occurs, and neither have yet told me otherwise (not in this individual aircraft; can't say the same for some other 912 units flown in)... the output shaft is also operating in a state of harmonic balance thanks to the fitted Balance Master... the carburettor mixtures and carburettors are in perfect balance... the engine is a low compression setup... there is no aspect about the power-plant's current operational spectrum that gives any credibility to the debate... If the engine is not singing then its out of tune, set at the wrong rpm frequency, or both... under constant load there are a limited number of factors that can cause gear failure - insufficient fit-for-purpose material specification, sustained overheating beyond safe operating temperature range and allowable time of said material, sustained mechanical vibration at specific alternate frequencies, excessive mechanical impact of sliding contact surfaces due to backlash (there will always be an element of backlash required for component heat expansion), ingress of foreign matter such as swarf other particles dust sand etc.



The 912 power-plant is a great unit. Personally I would of done things a bit differently and produced a lighter unit with less moving pieces but i doubt anyone at rotax would be interested or want to pay me to produce a better more robust unit for them; they are a big company and the wheel just works fine the way it is.



Wear upon the gearbox drive dog and spur gears is a result of startup and shutdown mechanical impacting, and idling the motor while in an out of tune state... and that is all...



It is not expected many people in any mechanical field will share my experience; i'm truly grateful for the many excellent teachers i have had along the way. And am still often left amazed but accepting at what level of damage the majority of  human beings can achieve... could fill a text book with field stories, but thats about all I have to say on the matter today.

peterz(at)zutrasoft.com
Guest

Posted: Sun Dec 25, 2022 6:01 pm Post subject: What did you do with your europa this week - 22/12/22

Not to argue, i will just leave this link to explain my concerns. 4cyl 4strokes are murder on gearboxes driving under damped (lightly loaded) air propellers with their reverse torque pulses. The site has other pages discussing as well fwiw.

http://www.epi-eng.com/piston_engine_technology/torsional_excitation_from_piston_engines.htm

Cheers,

PeteZ 



 	  Quote: 	
		  On Dec 25, 2022, at 8:09 PM, Area-51 <goldsteinindustrial(at)gmail.com> wrote:



ï»¿--> Europa-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com>



Thanks and noted Peter...



After spending an entire lifetime pulling stuff apart and analysing cause and effect of mechanical component failure i'm totally unconvinced on this argument often presented, simply because the propeller is operating within a state of constant load resistance leaving both the drive and driven gears no opportunity for backlash while in this state; if there was backlash occurring that would be a serious design concern and source of vibration; at my level of experience my ears and bum would let me know as soon as this occurs, and neither have yet told me otherwise (not in this individual aircraft; can't say the same for some other 912 units flown in)... the output shaft is also operating in a state of harmonic balance thanks to the fitted Balance Master... the carburettor mixtures and carburettors are in perfect balance... the engine is a low compression setup... there is no aspect about the power-plant's current operational spectrum that gives any credibility to the debate... !

 If the engine is not singing then its out of tune, set at the wrong rpm frequency, or both... under constant load there are a limited number of factors that can cause gear failure - insufficient fit-for-purpose material specification, sustained overheating beyond safe operating temperature range and allowable time of said material, sustained mechanical vibration at specific alternate frequencies, excessive mechanical impact of sliding contact surfaces due to backlash (there will always be an element of backlash required for component heat expansion), ingress of foreign matter such as swarf other particles dust sand etc.



It is not expected many people in any mechanical field will share my experience, and am still often left amazed but accepting at what level of damage the majority of  human beings can achieve... could fill a text book with field stories, but thats about all I have to say on the matter today.





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=509788#509788

Area-51

Joined: 03 May 2021
Posts: 376

Posted: Sun Dec 25, 2022 8:06 pm Post subject: Re: What did you do with your europa this week - 22/12/22

Totally agree with the article... give me 12 or 36 cylinders any day of the week... and this article is exactly why engine rpm frequency is mentioned in my above commentary. 



In simple terms the enlightened engine operator is looking for the rpm load setting factor that offsets these cylinder firing pulses against the combined resistance load (torque requested) and centrifugal momentum inertia of all internal moving components whether 1 or 36 cylinder format... there may generally be three or even four rpm points where this will occur for each individual engine and these points are fugitive based upon the changeable factors of fuel, air, temperature, and mechanical clearances between moving components. This why the enlightened engine operator is able to quickly discern an out-of-tune state on a perfectly turned and balanced engine.



Experience and understanding, extended running of 181's engine at 4800rpm, 3800rpm, 1600rpm, 800rpm is not any concern for me. These are the harmonic frequencies of this individual engine for its set tuned state and minimal stressed points. If the engine is not singing the above factors are not synchronised; things will simply wear out sooner...



I am at a total loss as to why rotax have employed a slip dog coupling in the 912 gearbox without torque pulse damper springs...



If i want to set the above engine for 5200rpm then it will need further bench work on the breathing because at 5200rpm it aint singing at all.



A good place to start for anybody wanting to understand the totality of internal combustion engines is "Tuning For Speed" - Phil Irving, anybody that says they know stuff doesnt really know stuff unless they know this book cover to cover. Its one of my loaded questions when sourcing a suitable engine builder that i have no prior experience dealing with.



Over the years i have found that if you just shutup and listen most people excel at digging a hole for themselves by talking a lot of babble and waffle... thats the walk-away-factor... sometimes i learn something i never knew... works great!!

rparigoris

Joined: 24 Nov 2009
Posts: 780

Posted: Mon Dec 26, 2022 1:26 pm Post subject: Re: What did you do with your europa this week - 22/12/22

Hi Area 51

2 Questions below:

 I'm having a bit of a hard time following your thinking?:

"I am at a total loss as to why rotax have employed a slip dog coupling in the 912 gearbox without torque pulse damper springs"

I'm not too familiar to the set up without slipper clutch, but with the slipper clutch you in fact have a torque pulse damper spring in the form of Belville washers. When cylinder fires, it "winds up the spring" In reality it is not winding up, it is flattening the Belville washer that is in fact a spring which absorbs some power. Then when no cylinder is not firing, the spring unwinds and puts some power back to the prop shaft.



1) Please explain how you would better make a torque pulse damper? I'm pretty certain if all that would be needed is a compression spring plate as is often seen in an automotive clutch that Rotax would have used that instead of a high parts count dog solution. A propeller spinning is a pretty darn good gyroscope, it  really doesn't want to accelerate or deaccelerate.

As far as operating at 3,800RPM, I have been interested in the loitering power setting. I have asked several folks in the know and all thought it is not an issue for the gearbox. That said it is an issue if you are running on 100LL as even with TCP or Alcor, you are not making enough power to get rid of as much lead as compared to pushing more BTUs through the engine. On Mogas or no lead think things will be fine.



2) Rotax want's oil temperature to get to boiling during flight. I think at sender 190F will give hot oil 212F. I'm pretty sure loitering flight will not allow oil temp to get to 212. My question is why do you need to get to 212F during flight? The real reason I ask is on most of my cars rarely do I see 212F and haven't ever seen anything happen because of it.

Thx.

Ron P.

Area-51

Joined: 03 May 2021
Posts: 376

Posted: Mon Dec 26, 2022 1:49 pm Post subject: Re: What did you do with your europa this week - 22/12/22

The washers are there to preload the slipper clutch.



Go read the book...

rparigoris

Joined: 24 Nov 2009
Posts: 780

Posted: Mon Dec 26, 2022 2:09 pm Post subject: Re: What did you do with your europa this week - 22/12/22

Hi Area 51

I just had a look at the 912 with out slipper clutch and it too has Belville washers.

Yes it's true that you preload the Belville washers with slipper clutch, but I think you are missing the fact that they are also the torque pulse damper springs. The reason you need to preload the Belville washers with the slipper clutch is they are also used to keep the slipper clutch from slipping.

Have a look at the parts manual and look at the non slipper clutch gearbox and low and behold they have a set of Belville washers. 

Ron P.

peterz(at)zutrasoft.com
Guest

Posted: Mon Dec 26, 2022 2:39 pm Post subject: What did you do with your europa this week - 22/12/22

Uh, actually, no.  The slipper clutch is set by screwing the clutch assembly tight, and is much higher breakaway torque than the dogs.



The main Bellevilleâ€™s set the friction in the dog, as set by the shims and measured using the crank lock and 20ft-lb minimum prop rotation friction test (on the flatâ€™s).



As for the low rpm running,  the dogs get pocketed and worn when the underloaded prop mass resonates with the engineâ€™s reverse torque pulses.  Once in resonance the positive feedback drives the system (like aero flutter of control surfaces).



Best way to avoid any resonance and messing up the dogs is to avoid the resonant frequencies (dependent upon prop rotating inertia), and loading up the prop with power.



Fwiw,

Cheers,

PeteZ



 	  Quote: 	
		   On Dec 26, 2022, at 4:55 PM, Area-51 <goldsteinindustrial(at)gmail.com> wrote:

 

 ï»¿

 

 The washers are there to preload the slipper clutch.

 

 Go read the book...

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=509799#509799

peterz(at)zutrasoft.com
Guest

Posted: Mon Dec 26, 2022 2:42 pm Post subject: What did you do with your europa this week - 22/12/22

Fwiw, I was told by the rotax folks that the slipper clutch was added to avoid spline damage during start-up/shut-down with heavy (high rotational mass) propellors.  

(Not prop strikes as commonly thought)



Cheers,

PeteZ



 	  Quote: 	
		   On Dec 26, 2022, at 4:33 PM, rparigoris <rparigor(at)hotmail.com> wrote:

 

 ï»¿

 

 Hi Area 51

 2 Questions below:

 I'm having a bit of a hard time following your thinking?:

 "I am at a total loss as to why rotax have employed a slip dog coupling in the 912 gearbox without torque pulse damper springs"

 I'm not too familiar to the set up without slipper clutch, but with the slipper clutch you in fact have a torque pulse damper spring in the form of Belville washers. When cylinder fires, it "winds up the spring" In reality it is not winding up, it is flattening the Belville washer that is in fact a spring which absorbs some power. Then when no cylinder is not firing, the spring unwinds and puts some power back to the prop shaft.

 

 1) Please explain how you would better make a torque pulse damper? I'm pretty certain if all that would be needed is a compression spring plate as is often seen in an automotive clutch that Rotax would have used that instead of a high parts count dog solution. A propeller spinning is a pretty darn good gyroscope, it  really doesn't want to accelerate or deaccelerate.

 

 

 As far as operating at 3,800RPM, I have been interested in the loitering power setting. I have asked several folks in the know and all thought it is not an issue for the gearbox. That said it is an issue if you are running on 100LL as even with TCP or Alcor, you are not making enough power to get rid of the as much lead as compared to pushing more BTUs through the engine. On Mogas or no lead think things will be fine.

 

 2) Rotax want's oil temperature to get to boiling during flight. I thyink at sender 190F will give hot oil 212F. I'm pretty sure loitering flight will not allow oil temp to get to 212. My question is why do you need to get to 212F during flight? The real reason I ask is on most of my cars rarely do I see 212F and haven't ever seen anything happen because of it.

 Thx.

 Ron P.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=509798#509798

Area-51

Joined: 03 May 2021
Posts: 376

Posted: Mon Dec 26, 2022 3:41 pm Post subject: Re: What did you do with your europa this week - 22/12/22

Which preload spring set are we talking about here? set 3 or 4? image attached...



To be honest this is a subject matter that appears to have been hotly debated for ever; its just not worth waisting any more valuable time upon.



"parts require periodic replacement when beyond manufacturer specified serviceable limits, period"... 



Just replace the part and enjoy flying the aircraft... cheaper to replace dog or slipper clutch than an entire engine... couldn't care less if and when it requires replacement.



Would rather use my time to grow a fresh pumpkin than redesign a perfectly functioning wheel...

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peterz(at)zutrasoft.com
Guest

Posted: Mon Dec 26, 2022 4:02 pm Post subject: What did you do with your europa this week - 22/12/22

Set 3 is for the dogs to set the (resonance damping) friction and to define the ramp torque and is in-play in flight. Set 4 is for the overload clutch to set its breakaway torque and never comes into play in flight, but rather only when the dogs have hit their compression stops to save the splines from deformation (which can occur with heavy props at start and stop or kickback).



Cheers,

PeteZ



 	  Quote: 	
		   On Dec 26, 2022, at 6:47 PM, Area-51 <goldsteinindustrial(at)gmail.com> wrote:

 

 ï»¿

 

 Which spring set are we talking about here? set 3 or 4? image attached...

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=509803#509803

 

 

 

 

 Attachments: 

 

 http://forums.matronics.com//files/c657a9f9_fcec_472e_af43_bcddb3aedfb4_150.jpeg

Area-51

Joined: 03 May 2021
Posts: 376

Posted: Mon Dec 26, 2022 4:48 pm Post subject: Re: What did you do with your europa this week - 22/12/22

Yes that makes sense of the madness employed... And yes the dogs will wear out at some stage one way or the other; or cone spring will crack and fail just like in a mercedes transmission... ðŸ‘ ðŸ¤©

peterz(at)zutrasoft.com
Guest

Posted: Mon Dec 26, 2022 5:06 pm Post subject: What did you do with your europa this week - 22/12/22

Always trying to tame the 4bangars resonance issues, rotax have changed to a torsion bar concept in the new 915.



Cheers,

PeteZ



 	  Quote: 	
		   On Dec 26, 2022, at 7:55 PM, Area-51 <goldsteinindustrial(at)gmail.com> wrote:

 

 ï»¿

 

 Yes that makes sense of the madness employed... And yes the dogs will wear out at some stage one way or the other; or cone spring will crack and fail just like in a mercedes transmission... ðŸ‘ ðŸ¤©

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=509805#509805

peterz(at)zutrasoft.com
Guest

Posted: Mon Dec 26, 2022 5:19 pm Post subject: What did you do with your europa this week - 22/12/22

The new 915 box uses two clutch packs and the the torsion shaft instead of the expensive (2200USD) dog gear assembly. Thanks to certification sadly weâ€™ll never see this new solution applied to the 912S.

https://www.rotax-owner.com/manuals/MMH_915i_A_Series_ED0_R0.pdf



 	  Quote: 	
		  On Dec 26, 2022, at 8:06 PM, Pete <peterz(at)zutrasoft.com> wrote:



ï»¿Always trying to tame the 4bangars resonance issues, rotax have changed to a torsion bar concept in the new 915.



Cheers,

PeteZ



 	  Quote: 	
		  On Dec 26, 2022, at 7:55 PM, Area-51 <goldsteinindustrial(at)gmail.com> wrote:



ï»¿--> Europa-List message posted by: "Area-51" <goldsteinindustrial(at)gmail.com>



Yes that makes sense of the madness employed... And yes the dogs will wear out at some stage one way or the other; or cone spring will crack and fail just like in a mercedes transmission... ðŸ‘ ðŸ¤©





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=509805#509805

	


	


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Area-51

Joined: 03 May 2021
Posts: 376

Posted: Mon Dec 26, 2022 5:43 pm Post subject: Re: What did you do with your europa this week - 22/12/22

So does a $35 donut...ðŸ¤·ðŸ¼â€â™‚ï¸



I like donuts ðŸ¤©ðŸ©



I like donuts a lot... just not when the word Joe precedes Donuts in the same sentence... ðŸ™†â€â™‚ï¸ðŸ¤¦ðŸ»â€â™‚ï¸



Other people have also successfully liked donuts a lot for decades!!! ðŸ˜Š



Clearly the 912/914 solution "must" be flawed then ðŸ¤”ðŸ¤”ðŸ¤”ðŸ¤”ðŸ¤·ðŸ¼â€â™‚ï¸ðŸ¤·ðŸ¼â€â™‚ï¸



Solution might = keep enjoying more donuts!! ðŸ˜‚ðŸ˜‚ðŸ˜‚ðŸ¤·ðŸ¼â€â™‚ï¸ðŸ¤·ðŸ¼â€â™‚ï¸



I will fill my gearbox with donuts ðŸ¤”ðŸ¤”ðŸ¤”ðŸ¤”ðŸ¤ªðŸ¤ªðŸ¤ªðŸ¤ª

JohnFrance

Joined: 17 Sep 2014
Posts: 77
Location: Grenoble France

Posted: Tue Dec 27, 2022 5:19 am Post subject: Re: What did you do with your europa this week - 22/12/22

I agree about the donuts, my triumph GT6 Mk2 had them on the drive shafts. 

I also know someone who used them on his ultralight which used a car diesel engine. When it failed he lost drive to the prop and the forced landing totalled the aircraft. That may be why Rotax didnâ€™t use them in the gearbox.

A very interesting thread this one all the same.

_________________
Europa mono Nr 192

peterz(at)zutrasoft.com
Guest

Posted: Tue Dec 27, 2022 6:54 am Post subject: What did you do with your europa this week - 22/12/22

Indeed, once resonance does take hold, the energy which must be dissipated quickly destroys rubber donuts. This is the reason that rotax only got away with them on two strokes which have trivial reverse torque pulses. Automotive applications are a different paradigm altogether as the ground presents an infinite damping load reducing the frequencies involved vs a free air propellor although the analogue does still exist: the situation when a student manual transmission driver pops the clutch at idle and the car lurches back and forth with increasing amplitude until it either stalls (a good thing) or something breaks.



In aircraft applications, the lightly loaded and under damped (in air) propellor mass can quickly increase the positive feedback resonance amplitude and thus power in the system until things break or the mechanical wear (dogs for example) becomes destructive (creating exasperating dog-pockets for example). All at low power input settings by definition. Give full power and the air provides sufficient damping load to avoid positive feedback resonance - and why this phenomenon is not seen in marine drives (water is a terrific damping medium). The very efficient slippery europa design feeds into this problem vs those draggy bush plane applications.



Auto conversions with simplistic rubber dampers (read: viking) are inadequate imhoâ€¦and time will tell as fleet time builds. The sprague solution in the yamaha/teal world are already seeing excessive low time field failures - as predicted by that website i had quoted.



 Fwiw,

Cheers,

PeteZ



 	  Quote: 	
		   On Dec 27, 2022, at 8:27 AM, JohnFrance <77alembert(at)gmail.com> wrote:

 

 ï»¿

 

 I agree about the donuts, my triumph GT6 Mk2 had them on the drive shafts. 

 I also know someone who used them on his ultralight which used a car diesel engine. When it failed he lost drive to the prop and the forced landing totalled the aircraft. That may be why Rotax didnâ€™t use them in the gearbox.

 A very interesting thread this one all the same.

 

 --------

 Europa mono Nr 192

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=509810#509810

Area-51

Joined: 03 May 2021
Posts: 376

Posted: Tue Dec 27, 2022 11:56 am Post subject: Re: What did you do with your europa this week - 22/12/22

Thanks Peter great explanation there; and yes donuts are great but when they break and when they do everything shakes to pieces real fast. So in an aircraft not a great idea for prop drive; it would require some variant which i will try out when a dead gearbox gets donated.



The ultimate solution to this rotax component wear issue is not fly ðŸ˜Š

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