X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail16.syd.optusnet.com.au ([211.29.132.197] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with ESMTPS id 985597 for flyrotary@lancaironline.net; Sun, 05 Jun 2005 18:25:10 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.132.197; envelope-from=lendich@optusnet.com.au Received: from george (d220-236-73-161.dsl.nsw.optusnet.com.au [220.236.73.161]) by mail16.syd.optusnet.com.au (8.12.11/8.12.11) with SMTP id j55MOIqn021648 for ; Mon, 6 Jun 2005 08:24:19 +1000 Message-ID: <004c01c56a1e$0732f3b0$a149ecdc@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: sand casting porosity Date: Mon, 6 Jun 2005 08:29:24 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0049_01C56A71.D86DF260" 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_0049_01C56A71.D86DF260 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Your right Al - defensive isn't the word. These small foundries, = although very good, operate at a very basic level and don't like being = told what to do. I guess I'm lucky as my first job at the age of 14 was = in a foundry - this gives me some leverage. However the information wasn't provided by the foundry but by the = supplier Comalco ( General Manager). Her did say there was more than = hydrogen that caused bubbles, which I must follow-up on. I guess I will have to be an expert on 'Bubbles' now! Anyhow I identified that they were round bubbles not elongated ones - = round bubbles ( it would seem) strongly indicate hydrogen porosity. I understand and appreciate your strategy - it would be difficult to = verify or measure in a small foundry environment. Your strategy to = correctly identify the culprit and then work to eliminate it, is a valid = one. It would appear that porosity is a gremlin that effects may metal = castings, not just aluminium. George ( down under) There is a valuable lesson in problem solving here George. Very = familiar pattern that really does apply to our rotary opportunities. Here's what I suggest. Don't tell your foundry guy you are discussing = this with someone, that will just get him defensive. Instead, ask = him:"How do you know the quantity of hydrogen in the alloy?". He's going = to give you some theoretical based statement. So tell him"Pretend I'm = the hydrogen fairy and the quantity just doubled in that bath, how would = you know it's actually double?" You'll likely find he doesn't really = know. He'll say "We could blah blah", but you ask him how often they = MEASURE it and you'll start to appreciate they have no facts that prove = hydrogen affects their casting process. It's all just theory. All of us tend to make decisions based on theory. An important key to = success in problem solving is to just find a simple way to convert the = theory to facts. This is rarely done. So when someone says:" I think = this will make things better", you need to say :"Lets prove it....let's = do the opposite and see if it gets worse!" So here's the deal, the foundry guy knows that the hydrogen level = increases if you raise the temp of aluminum. That's a theory, it's true. = But it's not significant. It's not the thing that affects the outcome. = Just because something is true does not mean it's significant. You have = to also test the idea for significance.=20 Yes, familiar with nitrogen bubbling.=20 -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 Sun, 5 Jun 2005 16:44:16 +1000 "George Lendich" = writes: 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_0049_01C56A71.D86DF260 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Your right Al - defensive isn't the word. These = small=20 foundries, although very good, operate at a very basic level and don't = like=20 being told what to do. I guess I'm lucky as my first job at the age of = 14 was in=20 a foundry - this gives me some leverage.
 
However the information wasn't provided by the = foundry=20 but by the supplier Comalco ( General Manager). Her did say there was = more than=20 hydrogen that caused bubbles, which I must follow-up = on.
I guess I will have to be an expert on 'Bubbles'=20 now!
 
Anyhow I identified that they were round bubbles not = elongated=20 ones - round bubbles ( it would seem) strongly indicate hydrogen=20 porosity.
 
I understand and appreciate your strategy - it would = be=20 difficult to verify or measure in a small foundry environment. Your = strategy to=20 correctly identify the culprit and then work to eliminate it, is a valid = one.
 
It would appear that porosity is a gremlin that = effects may=20 metal castings, not just aluminium.
George ( down under)
There is a valuable lesson in problem solving here George. Very = familiar=20 pattern that really does apply to our rotary opportunities.
Here's what I suggest. Don't tell your foundry guy you are = discussing=20 this with someone, that will just get him defensive. Instead, ask=20 him:"How do you know the quantity of hydrogen in the = alloy?". He's=20 going to give you some theoretical based statement. So tell = him"Pretend I'm=20 the hydrogen fairy and the quantity just doubled in that bath, how = would you=20 know it's actually double?" You'll likely find he doesn't really know. = He'll=20 say "We could blah blah", but you ask him how often they MEASURE it = and you'll=20 start to appreciate they have no facts that prove hydrogen affects = their=20 casting process. It's all just theory.
 
All of us tend to make decisions based on theory. An important = key to=20 success in problem solving is to just find a simple way to convert the = theory=20 to facts. This is rarely done. So when someone says:" I think this = will make=20 things better", you need to say :"Lets prove it....let's do the = opposite and=20 see if it gets worse!"
 
So here's the deal, the foundry guy knows that the hydrogen level = increases if you raise the temp of aluminum. That's a theory, it's = true. But=20 it's not significant. It's not the thing that affects the outcome. = Just because something is true does not mean it's = significant.=20 You have to also test the idea for significance. =
 
 
 Yes, familiar with nitrogen bubbling.

-al wick
Artificial intelligence in cockpit, Cozy IV = powered by=20 stock Subaru 2.5
N9032U 200+ hours on engine/airframe from = Portland,=20 Oregon
Prop construct, Subaru install, Risk assessment, Glass panel = design=20 = info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
=
 
On Sun, 5 Jun 2005 16:44:16 +1000 "George Lendich" <lendich@optusnet.com.au>=20 writes:
Al,
All good info, it's good to talk to someone in = the know.=20 We have looked into the vent and riser potential and this = has been=20 optimised. Shrinkage defects can be eliminated with the right number = of=20 risers, 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=20 the possibility of hydrogen? 
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=20 want to avoid shrinkage in high stress areas. It's most likely to = develop=20 at inside corners near thick sections of casting. A good foundry = can take=20 action to minimize risk. Depends on details, but they can add = vent, or=20 riser as needed. We also used special sand for optimum qualities. = But it=20 would likely be unnecessary for your application.
I conducted a number of statistically designed experiments to = optimize the process. The goal being to reduce the likelihood of = shrinkage=20 defects. 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.=20 Lot 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=20 castings for Aviation use. My initial challenge was a multi use=20 bellhousing to accommodate Aussie PSRU and that of = Tracy's=20 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=20 injection technology. This is expensive and not cost effective=20 because of the projected low demand, = probably=20 one to 2 hundred (at most), in an initial 2/3 year = period.
I settled on sand cast technology, = but because of=20 the thinness of some of the pattern, the aluminium is heated = beyond it's=20 recommended melting temps, to allow for easier running into = thinner area=20 before the temps are reduced by the sand casting=20 process. 
 
The initial trial did identify obvious = porosity,=20 throughout the pattern although later trials, being carried out = in the=20 USA have yet to identify any significant reduction in the = projected=20 strength 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=20 Element Analysis, was CAD designed, with myself making the = pattern to=20 exacting tolerances, due to design restrictions and as Butch's = exacting=20 demands - 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=20 competent foundry.
 
If I can quote Butch's recent remarks to me = "=20 The Bellhousing arrived safe and sound (Excellent = Packaging)..... Very=20 Robust to say the least, should be able to handle 800hp at = least. It has=20 been Ultrasonically analysed for density and voids, point load = tested=20 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=20 and testing by competent authority!! - even the=20 packaging!
 
To a unenlightened onlooker, on initially = first seeing=20 this bellhousing, their response might be this design might = not=20 meet what we normally accept as a bell-shaped design i.e. form = not=20 meeting design requirements etc. etc.
 
This is the type of development work carried = out by=20 many Experimental designers - but not = necessarily communicated to=20 everyone to this degree. I won't say this is true in all Rotary=20 installations, but I will say there is much in the way of = skilled and=20 talented builders involved in the process of the Rotary=20 development.
 
The point I'm trying to make is, although I = believe=20 your risk analysis is valid, I believe it is only valid when the = information you base your assessment is correct and complete. = Often a=20 valid assessment can be completely turned on it's head when = seemingly=20 correct information is found to be incomplete, therefore making = the=20 initial assessment completely useless. I believe some = assertions, on=20 this discussion group, have pointed 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=20 you know of any I would love to hear about it. One of the = problems=20 on supply to the USA, is the 'Tyranny of Distance'.
George ( down under)
 
 
I only did hydrogen experiments with = permanent=20 mold castings(thick wall parts), so unsure if it applies to = other=20 types. But the experiments were conclusive. Hydrogen was = absolutely=20 trivial. It was shrinkage porosity which dominates the = mechanical=20 properties. Hydrogen porosity develops round = voids, shrinkage=20 voids tear.  
 
I suspect the myth continues regarding hydrogen. I did = those=20 experiments over 10 years ago. It gave us huge advantage over=20 competition. We focused on methods to reduce shrinkage = defects. Ended=20 up out performing our competition. That was a blast. I miss = those=20 challenges.
 

-al wick
Artificial intelligence in cockpit, Cozy = IV=20 powered by stock Subaru 2.5
N9032U 200+ hours on = engine/airframe=20 from Portland, Oregon
Prop construct, Subaru install, Risk=20 assessment, Glass panel 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=20 of course procurement. I had a good deal of experience = within the=20 medical logistics field.
This basic approach gives a basic = guide=20 provided you get your facts straight and work on with the = right=20 information - I can't see this being done with the Rotary. = Perhaps=20 he has done quite well with the Subaru - who would=20 know.
 
Al if your on here would you please = elaborate on=20 the statement on Aluminium - the information to me is that = Hydrogen=20 is 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=20 in the aluminium, the higher the humidity the greater the = chace of=20 Hydrogen 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=20 not following his own process (I think I alluded to this = previously). First, you have to ask, "How many failures = have=20 accurred due to a faulty CAS?"  That's=20 a fair question.  Do you know?  Does = anyone?  If=20 so, Who?  Seems there was a thread around that just = a month=20 or two ago.   Intuitively, I would say that CAS = would be a=20 single point of failure, important enough to be=20 remediated.  The text below is copy and = pasted=20 from  http= ://www.maddyhome.com/canardpages/pages/alwick/risk.html=20 The key phrase is the last sentence.

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

There are only three pieces to = the=20 puzzle.   In the case of = CAS (just=20 my guess)

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

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

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

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