X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail23.syd.optusnet.com.au ([211.29.133.164] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with ESMTPS id 985058 for flyrotary@lancaironline.net; Sun, 05 Jun 2005 02:40:03 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.133.164; envelope-from=lendich@optusnet.com.au Received: from george (d220-236-73-161.dsl.nsw.optusnet.com.au [220.236.73.161]) by mail23.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j556dBn8010227 for ; Sun, 5 Jun 2005 16:39:12 +1000 Message-ID: <011001c56999$fe687ae0$a149ecdc@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] sand casting porosity Date: Sun, 5 Jun 2005 16:44:16 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_010D_01C569ED.CF9289A0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_010D_01C569ED.CF9289A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Al, All good info, it's good to talk to someone in the know. We have looked = into the vent and riser potential and this has been optimised. Shrinkage = defects can be eliminated with the right number of risers, in the right = places especially in (as you say) thicker areas of thin castings. There is a strategy for eliminating Hydrogen from molten aluminium and = that is to purge with Nitrogen ( Nitrogen bonds to hydrogen molecules - = so I'm led to believe) through a ceramic wand ( immersed in the = aluminium) for approx 20/30 minutes. Have you tried this method to = eliminate the possibility of hydrogen?=20 George ( down under) Oh, why didn't you say it was sand cast? 90% probability your porosity = was shrinkage porosity, nothing to do with hydrogen. You sure want to = avoid shrinkage in high stress areas. It's most likely to develop at = inside corners near thick sections of casting. A good foundry can take = action to minimize risk. Depends on details, but they can add vent, or = riser as needed. We also used special sand for optimum qualities. But it = would likely be unnecessary for your application.=20 I conducted a number of statistically designed experiments to optimize = the process. The goal being to reduce the likelihood of shrinkage = defects. Total blast doing that kind of stuff.=20 The nature of shrinkage porosity is that it comes and goes. So most = foundries have hard time identifying contributing causes and optimizing. = Lot of statistical noise.=20 Good luck in your endeavor! -al wick On Sun, 5 Jun 2005 13:18:44 +1000 "George Lendich" = writes: Al, There's reasons for my enquiry, which involves castings for Aviation = use. My initial challenge was a multi use bellhousing to accommodate = Aussie PSRU and that of Tracy's unit. It doubles as a engine mount and accommodates 5 ( maybe more) = starter types and has to be light and strong. This requires strong thin = wall castings. Usually thin walled castings require pressure injection technology. = This is expensive and not cost effective because of the projected low = demand, probably one to 2 hundred (at most), in an initial 2/3 year = period. I settled on sand cast technology, but because of the thinness of = some of the pattern, the aluminium is heated beyond it's recommended = melting temps, to allow for easier running into thinner area before the = temps are reduced by the sand casting process.=20 The initial trial did identify obvious porosity, throughout the = pattern although later trials, being carried out in the USA have yet to = identify any significant reduction in the projected strength = requirements. My development partner in the States, Butch as he is affectionally = know throughout the Industry - is an Aviation Engineer. This design has been thoroughly tested on Finite Element Analysis, = was CAD designed, with myself making the pattern to exacting tolerances, = due to design restrictions and as Butch's exacting demands - he's a hard = man to please! Although this took some considerable time ( approx 12 months) the = pattern was completed and the prototypes done, by a very competent = foundry. If I can quote Butch's recent remarks to me " The Bellhousing = arrived safe and sound (Excellent Packaging)..... Very Robust to say the = least, should be able to handle 800hp at least. It has been = Ultrasonically analysed for density and voids, point load tested and = torque twisting along both the horizontal and vertical axis. Needless to say it passed with "Flying Colours!!=20 Do you see a pattern developing here? Research design and testing by = competent authority!! - even the packaging! To a unenlightened onlooker, on initially first seeing this = bellhousing, their response might be this design might not meet what we = normally accept as a bell-shaped design i.e. form not meeting design = requirements etc. etc. This is the type of development work carried out by many = Experimental designers - but not necessarily communicated to everyone to = this degree. I won't say this is true in all Rotary installations, but I = will say there is much in the way of skilled and talented builders = involved in the process of the Rotary development. The point I'm trying to make is, although I believe your risk = analysis is valid, I believe it is only valid when the information you = base your assessment is correct and complete. Often a valid assessment = can be completely turned on it's head when seemingly correct information = is found to be incomplete, therefore making the initial assessment = completely useless. I believe some assertions, on this discussion group, = have pointed to this possibility. BTW I'm on the look out for any good foundries around the East = Coast Nth of Washington, who could carry out this Bellhousing work ' = Cost Effectively', for the US market, if you know of any I would love = to hear about it. One of the problems on supply to the USA, is the = 'Tyranny of Distance'. George ( down under) I only did hydrogen experiments with permanent mold castings(thick = wall parts), so unsure if it applies to other types. But the experiments = were conclusive. Hydrogen was absolutely trivial. It was shrinkage = porosity which dominates the mechanical properties. Hydrogen porosity = develops round voids, shrinkage voids tear. =20 I suspect the myth continues regarding hydrogen. I did those = experiments over 10 years ago. It gave us huge advantage over = competition. We focused on methods to reduce shrinkage defects. Ended up = out performing our competition. That was a blast. I miss those = challenges. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock = Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel = design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html On Sat, 4 Jun 2005 08:32:19 +1000 "George Lendich" = writes: I've had a look at Al Wicks approach and for me it leaves a lot = of unanswered questions. I have the benefit of being a ( now retired) = Government Logistics manager, trained in Quality Assurance, = Occupational Health and Safety, Risk management and of course = procurement. I had a good deal of experience within the medical = logistics field. This basic approach gives a basic guide provided you get your = facts straight and work on with the right information - I can't see this = being done with the Rotary. Perhaps he has done quite well with the = Subaru - who would know. Al if your on here would you please elaborate on the statement = on Aluminium - the information to me is that Hydrogen is indeed the = major problem with non- injection cast aluminium. Especially if it = involves elevated thin pour castings - the elevated temperature draws = hydrogen from the air and releases it as bubbles in the aluminium, the = higher the humidity the greater the chace of Hydrogen porosity. As we all know porosity is the primary cause of strength = reduction in a cast aluminium piece. I understand there are other causes = of porosity, but am unsure of what they all are. George ( down under) Ernest Christley wrote: Jim, Al is not following his own process (I think I alluded = to this previously). First, you have to ask, "How many failures have = accurred due to a faulty CAS?" That's a fair question. Do you know? = Does anyone? If so, Who? Seems there was a thread around that just a = month or two ago. Intuitively, I would say that CAS would be a single = point of failure, important enough to be remediated. The text below is = copy and pasted from = http://www.maddyhome.com/canardpages/pages/alwick/risk.html The key = phrase is the last sentence.=20 We are going to do an FMEA. What is the goal we are trying = to achieve with this process? It's to make sure we place our efforts on = the facets which need it. Put another way, it's making sure we don't = waste time and effort on insignificant items, while ignoring the truly = important items.=20 There are only three pieces to the puzzle. In the case of = CAS (just my guess) 1) If the component failed, how serious would that effect = the airplane? catastrophic 2) What is the probability of the component failing? = Undetermined. Start with doing some research at NAPA et al and repair = shops around how many they sell. 3) What is the likelihood that you would notice the problem = before failure? I'd guess very VERY remote. You may have heard statements like "You have to replace = component x on your engine before installing into an airplane because it = represents a single point failure". Meaning that if x fails, there is no = backup component. That statement is not meaningful until you assess all = three questions above.=20 Exactly. Al's question is "... to what extent are "we" = using his methodology. My own guess would be "not much ...". Single = point(s) of failure in Tracy's ignition (and fuel control) systems - if = there are any - would be a case in point. As would redundant fuel pumps = powered by a single source, and charging systems that are not = sufficiently redundant and with appropriate indicators. If one DOES = have a single point of failure (and there are inevitably many) we must = be sure that that component is sufficiently robust to give us all = confidence that it will NOT fail. >> Homepage: http://www.flyrotary.com/ >> Archive: http://lancaironline.net/lists/flyrotary/List.html -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru = 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design = info: http://www.maddyhome.com/canardpages/pages/alwick/index.html ------=_NextPart_000_010D_01C569ED.CF9289A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Al,
All good info, it's good to talk to someone in the = know. We=20 have looked into the vent and riser potential and this has = been=20 optimised. Shrinkage defects can be eliminated with the right number of = risers,=20 in the right places especially in (as you say) thicker areas of thin=20 castings.
There is a strategy for eliminating Hydrogen from = molten=20 aluminium and that is to purge with Nitrogen ( Nitrogen bonds to = hydrogen=20 molecules - so I'm led to believe) through a ceramic wand ( immersed in = the=20 aluminium) for approx 20/30 minutes. Have you tried this method to = eliminate the=20 possibility of hydrogen? 
George ( down under)
Oh, why didn't you say it was sand cast? 90% probability your = porosity=20 was shrinkage porosity, nothing to do with hydrogen. You sure want to = avoid=20 shrinkage in high stress areas. It's most likely to develop at inside = corners=20 near thick sections of casting. A good foundry can take action to = minimize=20 risk. Depends on details, but they can add vent, or riser as needed. = We also=20 used special sand for optimum qualities. But it would likely be = unnecessary=20 for your application.
I conducted a number of statistically designed experiments to = optimize=20 the process. The goal being to reduce the likelihood of shrinkage = defects.=20 Total blast doing that kind of stuff.
The nature of shrinkage porosity is that it comes and goes. So = most=20 foundries have hard time identifying contributing causes and = optimizing. Lot=20 of statistical noise.
 
Good luck in your endeavor!
 
-al wick
 
 
On Sun, 5 Jun 2005 13:18:44 +1000 "George Lendich" <lendich@optusnet.com.au>=20 writes:
Al,
There's reasons for my enquiry, which involves = castings=20 for Aviation use. My initial challenge was a multi use bellhousing = to=20 accommodate Aussie PSRU and that of Tracy's = unit.
It doubles as a engine mount = and accommodates 5 (=20 maybe more) starter types and has to be light and strong. This = requires=20 strong thin wall castings.
Usually thin walled castings require pressure = injection=20 technology. This is expensive and not cost effective=20 because of the projected low demand, = probably one=20 to 2 hundred (at most), in an initial 2/3 year period.
I settled on sand cast technology, = but because of the=20 thinness of some of the pattern, the aluminium is heated beyond it's = recommended melting temps, to allow for easier running into thinner = area=20 before the temps are reduced by the sand casting = process. 
 
The initial trial did identify obvious porosity, = throughout the pattern although later trials, being carried out in = the USA=20 have yet to identify any significant reduction in the projected = strength=20 requirements.
 
My development partner in the States, Butch as = he is=20 affectionally know throughout the Industry - is an Aviation=20 Engineer.
This design has been thoroughly tested on Finite = Element=20 Analysis, was CAD designed, with myself making the pattern to = exacting=20 tolerances, due to design restrictions and as Butch's exacting = demands -=20 he's a hard man to please!
 
Although this took some considerable time ( = approx 12=20 months) the pattern was completed and the prototypes done, by a very = competent foundry.
 
If I can quote Butch's recent remarks to me = " The=20 Bellhousing arrived safe and sound (Excellent Packaging)..... Very = Robust to=20 say the least, should be able to handle 800hp at least. It has been=20 Ultrasonically analysed for density and voids, point load tested and = torque twisting along both the horizontal and vertical=20 axis.
Needless to say it passed with "Flying=20 Colours!! 
 
Do you see a pattern developing here? Research = design and=20 testing by competent authority!! - even the = packaging!
 
To a unenlightened onlooker, on initially first = seeing=20 this bellhousing, their response might be this design might not = meet=20 what we normally accept as a bell-shaped design i.e. form not = meeting design=20 requirements etc. etc.
 
This is the type of development work carried out = by many=20 Experimental designers - but not necessarily communicated to = everyone=20 to this degree. I won't say this is true in all Rotary = installations, but I=20 will say there is much in the way of skilled and talented builders = involved=20 in the process of the Rotary development.
 
The point I'm trying to make is, although I = believe your=20 risk analysis is valid, I believe it is only valid when the = information you=20 base your assessment is correct and complete. Often a valid = assessment can=20 be completely turned on it's head when seemingly correct information = is=20 found to be incomplete, therefore making the initial assessment = completely=20 useless. I believe some assertions, on this discussion group, have = pointed=20 to this possibility.
 
BTW I'm on the look out for any good = foundries=20 around  the East Coast Nth of Washington, who could carry out = this=20 Bellhousing work ' Cost Effectively',  for the US market, = if you=20 know of any I would love to hear about it. One of the problems = on=20 supply to the USA, is the 'Tyranny of Distance'.
George ( down under)
 
 
I only did hydrogen experiments with = permanent mold=20 castings(thick wall parts), so unsure if it applies to other = types. But=20 the experiments were conclusive. Hydrogen was absolutely trivial. = It was=20 shrinkage porosity which dominates the mechanical properties. = Hydrogen=20 porosity develops round voids, shrinkage voids tear. =  
 
I suspect the myth continues regarding hydrogen. I did those=20 experiments over 10 years ago. It gave us huge advantage over = competition.=20 We focused on methods to reduce shrinkage defects. Ended up out = performing=20 our competition. That was a blast. I miss those challenges.
 

-al wick
Artificial intelligence in cockpit, Cozy IV = powered=20 by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from = Portland,=20 Oregon
Prop construct, Subaru install, Risk assessment, Glass = panel=20 design=20 = info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
=
 
 
On Sat, 4 Jun 2005 08:32:19 +1000 "George Lendich" <lendich@optusnet.com.au>=20 writes:
I've had a look at Al Wicks approach and for = me it=20 leaves a lot of unanswered questions. I have the benefit of = being a (=20 now retired) Government Logistics manager, trained = in Quality=20 Assurance,  Occupational Health and Safety, Risk management = and of=20 course procurement. I had a good deal of experience within the = medical=20 logistics field.
This basic approach gives a basic guide = provided=20 you get your facts straight and work on with the right = information - I=20 can't see this being done with the Rotary. Perhaps he has done = quite=20 well with the Subaru - who would know.
 
Al if your on here would you please = elaborate on the=20 statement on Aluminium - the information to me is that Hydrogen = is=20 indeed the major problem with non- injection cast = aluminium.=20 Especially if it involves elevated thin pour castings - the = elevated=20 temperature draws hydrogen from the air and releases it as = bubbles in=20 the aluminium, the higher the humidity the greater the chace of = Hydrogen=20 porosity.
As we all know porosity is the primary cause = of=20 strength reduction in a cast aluminium piece. I understand there = are=20 other causes of porosity, but am unsure of what they all=20 are.
 
George ( down under)
Ernest=20 Christley wrote:
Jim, = Al is not=20 following his own process (I think I alluded to this = previously).=20 First, you have to ask, "How many failures have accurred due = to a=20 faulty CAS?"  That's a fair = question. =20 Do you know?  Does anyone?  If so, Who?  = Seems there=20 was a thread around that just a month or two ago.  =20 Intuitively, I would say that CAS would be a single point of = failure, important enough to be remediated.  The = text=20 below is copy and pasted from  http= ://www.maddyhome.com/canardpages/pages/alwick/risk.html=20 The key phrase is the last sentence.

We are going to = do an=20 FMEA. What is the goal we are trying to achieve with this = process?=20 It=92s to make sure we place our efforts on the facets which = need it.=20 Put another way, it=92s making sure we don=92t waste time = and effort on=20 insignificant items, while ignoring the truly important = items.=20

There are only three pieces to the = puzzle.   In the case of CAS (just my = guess)

1) If=20 the component failed, how serious would that effect the=20 airplane?  catastrophic

2)=20 What is the probability of the component failing? Undetermined.  Start with doing some = research at=20 NAPA et al and repair shops around how many they=20 sell.

3) What is the likelihood that you would = notice=20 the problem before failure?  I'd = guess very=20 VERY remote.

You may have heard statements = like =93You=20 have to replace component x on your engine before installing = into an=20 airplane because it represents a single point failure=94. = Meaning that=20 if x fails, there is no backup component. That statement is = not=20 meaningful until you assess all three questions above. =
Exactly.  Al's question is "... to what = extent=20 are "we" using his methodology.  My own guess would be = "not=20 much ...".  Single point(s) of failure in Tracy's = ignition (and=20 fuel control) systems - if there are any - would be a case = in=20 point.  As would redundant fuel pumps powered by a = single=20 source, and charging systems that are not sufficiently = redundant and=20 with appropriate indicators.  If one DOES have a single = point=20 of failure (and there are inevitably many) we must be sure = that that=20 component is sufficiently robust to give us all confidence = that it=20 will NOT fail.

>>  Homepage:  http://www.flyrotary.com/

>>  Archive:   =
http://lancaironline.net/lists/flyrotary/List.html
 
 

-al wick
Artificial = intelligence in=20 cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on=20 engine/airframe from Portland, Oregon
Prop construct, Subaru = install, Risk=20 assessment, Glass panel design=20 = info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
= ------=_NextPart_000_010D_01C569ED.CF9289A0--