Shock Cooling - Myth Busted!!
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Trent,
How ya doing
When I was patiently awaiting my clearance to drop.....me that is not meat bombs, I had no idea I would collect the data and start this thread, so I must admit, it was not planned, initially I reset the Assigned Altitude, changed frequency, pushed the nose over and had some cheeky banter with BNE APP, and wait till I see him next
So I did not pay much attention to the exact throttle position, and as altiude varies so does the available MP, and as RPM changes so does MP, so you can see variations all the way down. At some point I did start making a really concerted effort to get down and join the circuit at 1000', which on the day meant a join closer to me than the other side of the field. So between that and watching TAS, and then as that became less an issue watching yellow arc over the hills, the actual MP was not a concern.
I did not consider it at all until in the circuit area. I was packed up and home before I contemplated the data and its interest to others, so I downloaded the data a week later.
It is what it is, but even if I look back at other data files where I have done descents rapidly, it just proves that the Delta T is never remarkable no matter what.
It was an awesome view of Brisbane that I have never had before though!
Night all!
How ya doing
When I was patiently awaiting my clearance to drop.....me that is not meat bombs, I had no idea I would collect the data and start this thread, so I must admit, it was not planned, initially I reset the Assigned Altitude, changed frequency, pushed the nose over and had some cheeky banter with BNE APP, and wait till I see him next
So I did not pay much attention to the exact throttle position, and as altiude varies so does the available MP, and as RPM changes so does MP, so you can see variations all the way down. At some point I did start making a really concerted effort to get down and join the circuit at 1000', which on the day meant a join closer to me than the other side of the field. So between that and watching TAS, and then as that became less an issue watching yellow arc over the hills, the actual MP was not a concern.
I did not consider it at all until in the circuit area. I was packed up and home before I contemplated the data and its interest to others, so I downloaded the data a week later.
It is what it is, but even if I look back at other data files where I have done descents rapidly, it just proves that the Delta T is never remarkable no matter what.
It was an awesome view of Brisbane that I have never had before though!
Night all!
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Fathom, ask away!
I do have a path that is at times difficult with crossing traffic, especially at night or in IMC and can't descend visual. So I find the ATC guys appreciate or at least make noises such that I can give them a TOD that I would like well in advance, and also be flexible to go over or under the others.
I have had this discussion with said ATC at various school rugby games and so on, and on this occasion when the busy traffic level was apparent, I was prepared to go with the flow. But then it dawned on me who might be on BNE APP. He got me
It was all sport, and I could have reminded them, but I figured there was a game on, so I played the hand that was dealt.
Forkie will tell you similar things in TL.
There was no real problem and it was a good exercise in meeting a target from a great distance without the aid of an FMC, just my mental maths.
I was prepared for a clearance overhead the field, but that too cuts across the MLY-BN track and they want you out of the way of morno and tkfs coming through there at a great rate of knots!
cheers,
Jaba
I do have a path that is at times difficult with crossing traffic, especially at night or in IMC and can't descend visual. So I find the ATC guys appreciate or at least make noises such that I can give them a TOD that I would like well in advance, and also be flexible to go over or under the others.
I have had this discussion with said ATC at various school rugby games and so on, and on this occasion when the busy traffic level was apparent, I was prepared to go with the flow. But then it dawned on me who might be on BNE APP. He got me
It was all sport, and I could have reminded them, but I figured there was a game on, so I played the hand that was dealt.
Forkie will tell you similar things in TL.
There was no real problem and it was a good exercise in meeting a target from a great distance without the aid of an FMC, just my mental maths.
I was prepared for a clearance overhead the field, but that too cuts across the MLY-BN track and they want you out of the way of morno and tkfs coming through there at a great rate of knots!
cheers,
Jaba
Grandpa Aerotart
Prospector et al 'shock cooling' IS a myth.
What damaged those hard worked Flitcher engines was the heat put into them on climb NOT the rate of cooling on the descent.
This graph shows residual tensile strength vs heat in PW radial engines - identical metal/combustion etc to a modern flat engine. You will notice the tensile strength of aluminium is approximately half at the temperature that was/is considered 'redline' on our engines - 460F. The most likely cause of the damage you recall was repeatedly heating the cylinders up around 450F - which over time weakens the metal - and then you get a blown jug/cracks because that weakened metal can no longer withstand the internal pressures of the normal combustion event.
What damaged those hard worked Flitcher engines was the heat put into them on climb NOT the rate of cooling on the descent.
This graph shows residual tensile strength vs heat in PW radial engines - identical metal/combustion etc to a modern flat engine. You will notice the tensile strength of aluminium is approximately half at the temperature that was/is considered 'redline' on our engines - 460F. The most likely cause of the damage you recall was repeatedly heating the cylinders up around 450F - which over time weakens the metal - and then you get a blown jug/cracks because that weakened metal can no longer withstand the internal pressures of the normal combustion event.
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We never had a John Deakin, or an internet to get this information from. One cylinder head gauge, no way of knowing EGT, working engines a lot harder than they were ever designed for. Only time mixture was ever used was to shut down engine. Not suprising that not all engines made it to the official TBO. perhaps using cylinders till they eventually died, on second third or even fourth life explains why some appeared to have more trouble than others with cylinders cracking.
It was called Shock Cooling by our engineers, wrongly it would appear, but in the advice to young pilots it certainly made you more aware of engine handling procedures. ie, dont pull power from full throttle to nothing as you stuff the nose down in a race back to the strip.
What is suprising looking back is that the engines survived so many hours of such extremes of temperature changes for up to 1,200 hours. and sometimes more between overhauls.
On a good day 120 or more take offs could be carried out, with no way of knowing what was happening to Temps apart from the one cylinder head gauge, that may not have been on the hottest cylinder.
It was called Shock Cooling by our engineers, wrongly it would appear, but in the advice to young pilots it certainly made you more aware of engine handling procedures. ie, dont pull power from full throttle to nothing as you stuff the nose down in a race back to the strip.
What is suprising looking back is that the engines survived so many hours of such extremes of temperature changes for up to 1,200 hours. and sometimes more between overhauls.
On a good day 120 or more take offs could be carried out, with no way of knowing what was happening to Temps apart from the one cylinder head gauge, that may not have been on the hottest cylinder.
Last edited by prospector; 27th Aug 2012 at 23:12.
Jaba, I remember reading the Deakin articles when they were first written, and one of the things which sticks in my memory is the difficulty (impossibility?) of operating Lean Of Peak with the standard engines of the day as the mixtures were so unmatched in each cylinder. Deakin "fixed" this by using tuned Gami injectors to tweak the fuel flow to each cylinder, using his individual CHT information from his JPI engine gage.
So - question - do you run a standard original engine (ie. are engines that much better today?), or do you use after-market matched injectors?
edit: second question - you were at FL140? Were you on Oxygen or in a pressurised aircraft? If you were on O2, I'm sure you've also read Deakin's articles on using welder's oxygen and nasal cannulas with pulse oxymeters - is this what you were doing at FL140?
So - question - do you run a standard original engine (ie. are engines that much better today?), or do you use after-market matched injectors?
edit: second question - you were at FL140? Were you on Oxygen or in a pressurised aircraft? If you were on O2, I'm sure you've also read Deakin's articles on using welder's oxygen and nasal cannulas with pulse oxymeters - is this what you were doing at FL140?
Last edited by Checkboard; 28th Aug 2012 at 11:02.
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Gooday Checkers,
Regards to Reddo
Many years ago, say mid 90's and beyond nobody really bothered, until GAMI who with George Braly and Tim Roehl decided enough was enough.
John Deakin bought and I mean paid for set No1, Walter Atkinson paid for set No3. and George (&Tim) paid a heap for set No. 2, Mind you they own the business.
Prior to that engines had run LOP for 50 + years, Lindburgh and the Doolittle raiders would not be household names without it. FACT
Problem was TCM had poor induction and fuel delivery ratios, but they were at least uniform and consistent. Lycoming on the other hand had worse inductions, and worse still were not consistent or repeatable.
So GAMI solved this and they did it very cleverly by not just getting the fuel PPH (pounds per hour) correct to match the airflow, but they improved the back pressure at the injector tip and also the shape and a few other things of the nozzle to get a better spray. This is most important as you slow the flow rate down.
I think JD had more than a single point CHT, the eary JPI's had multi EGT and CHT. But thats a minor point.
My Lycoming, out of the box was to be honest a pig, a basket case. I have flown other identical genuine factory engines, straight out of the box that fly LOP even better than mine does today. Such is Lycomings ability to variation.
So with our engine I had to do a rough tune, just to get the thing to peak.....t would not even run smooth approaching peak as the spreads were so bad one stopped long before the others got close.
With much patience of my good friend Andrew Denyer at Riverina Airmotive we sent injectors back and forth and eventually got it about right. Even today I have what I consider just good enough. Too lazy to tweak one.....but I might if JD or others want some data logged that might need me more on spec.
So to answer your question I have tunned them however Andrew did the tiny reaming of the restrictors. For anyone thinking of doing this somehow themselves....DON'T BE STUPID......this is not a DIY job.
So in my case it has tuned injectors, yet some engines out of the box are fine. TCM(CMI) or Lycoming. Even George and Tim will not sell you GAMI's unless you need them.
As for FL's.....Trent is far more astute.....
FL130 my friend and I do use a Mountain High O2 setup, 4 place Oxymisers and it is awesome. Above 5000 at night(every time due LSALT) and when at or above 8K for longer than 2.5 hours, or always above 10K It is a major safety benefit! Glider guys swear by it and I can see why. I monitor with a pulse oximeter regularly both me and passengers.
So back to George.....I have the privilege of calling these guys my friends these days and I must say if I ever know as much as George Braly has forgotten, I will be the smartest bloke in GA in Australia. I kid you not, behind the scenes what this guy has done and is doing even today is mind blowing. Not all of it I can share here. But I can tell you that I have smelled tasted and seen all the data and test reports, even know what is the chemical makeup of the likely only replacement for leaded AVGAS. Only a month or two now from FAA certification, and it is going to make anyone with big radials like on conies, T28's or other big HP things who wish they had 100/145 but less the lead and the down sides, VERRRRY HAPPPPY indeed.
G100UL, is something that will be the biggest boost to GA in Australia. Period!. And USA and Europe. He should be knighted for his work. Some of you will scoff, but watch this space. george is a modest quiet man, and if you think the GAMI's were a big deal, TAT TN systems are good, or the Beech T34 wing box mod was something special, well hang on to your hats.
So this is major thread drift, but I feel it is important enough that in the next year or so it is likely all refineries in Australia will be able to produce G100UL, using existing gear, without special tank and transport, and there being no reason for a price rise, maybe even less. Heck I can brew my own! And be in spec. The good news is that G100UL, no matter how much 100LL is mixed with it, is still within spec. So changeover is a non issue. Cirrus have already written the approval for the Sr range and the POH amendments. That is confidence with a Capital G
So a lot has come from the humble tuned injector............more than most appreciate, especially T34 owners!
Want to know more come see Andrew Denyer or myself at Ausfly.
Clinton will be lurking here, what you say? Agreed?
Sorry Checkers for the thread drift......I got carried away.
Regards to Reddo
Many years ago, say mid 90's and beyond nobody really bothered, until GAMI who with George Braly and Tim Roehl decided enough was enough.
John Deakin bought and I mean paid for set No1, Walter Atkinson paid for set No3. and George (&Tim) paid a heap for set No. 2, Mind you they own the business.
Prior to that engines had run LOP for 50 + years, Lindburgh and the Doolittle raiders would not be household names without it. FACT
Problem was TCM had poor induction and fuel delivery ratios, but they were at least uniform and consistent. Lycoming on the other hand had worse inductions, and worse still were not consistent or repeatable.
So GAMI solved this and they did it very cleverly by not just getting the fuel PPH (pounds per hour) correct to match the airflow, but they improved the back pressure at the injector tip and also the shape and a few other things of the nozzle to get a better spray. This is most important as you slow the flow rate down.
I think JD had more than a single point CHT, the eary JPI's had multi EGT and CHT. But thats a minor point.
My Lycoming, out of the box was to be honest a pig, a basket case. I have flown other identical genuine factory engines, straight out of the box that fly LOP even better than mine does today. Such is Lycomings ability to variation.
So with our engine I had to do a rough tune, just to get the thing to peak.....t would not even run smooth approaching peak as the spreads were so bad one stopped long before the others got close.
With much patience of my good friend Andrew Denyer at Riverina Airmotive we sent injectors back and forth and eventually got it about right. Even today I have what I consider just good enough. Too lazy to tweak one.....but I might if JD or others want some data logged that might need me more on spec.
So to answer your question I have tunned them however Andrew did the tiny reaming of the restrictors. For anyone thinking of doing this somehow themselves....DON'T BE STUPID......this is not a DIY job.
So in my case it has tuned injectors, yet some engines out of the box are fine. TCM(CMI) or Lycoming. Even George and Tim will not sell you GAMI's unless you need them.
As for FL's.....Trent is far more astute.....
FL130 my friend and I do use a Mountain High O2 setup, 4 place Oxymisers and it is awesome. Above 5000 at night(every time due LSALT) and when at or above 8K for longer than 2.5 hours, or always above 10K It is a major safety benefit! Glider guys swear by it and I can see why. I monitor with a pulse oximeter regularly both me and passengers.So back to George.....I have the privilege of calling these guys my friends these days and I must say if I ever know as much as George Braly has forgotten, I will be the smartest bloke in GA in Australia. I kid you not, behind the scenes what this guy has done and is doing even today is mind blowing. Not all of it I can share here. But I can tell you that I have smelled tasted and seen all the data and test reports, even know what is the chemical makeup of the likely only replacement for leaded AVGAS. Only a month or two now from FAA certification, and it is going to make anyone with big radials like on conies, T28's or other big HP things who wish they had 100/145 but less the lead and the down sides, VERRRRY HAPPPPY indeed.
G100UL, is something that will be the biggest boost to GA in Australia. Period!. And USA and Europe. He should be knighted for his work. Some of you will scoff, but watch this space. george is a modest quiet man, and if you think the GAMI's were a big deal, TAT TN systems are good, or the Beech T34 wing box mod was something special, well hang on to your hats.
So this is major thread drift, but I feel it is important enough that in the next year or so it is likely all refineries in Australia will be able to produce G100UL, using existing gear, without special tank and transport, and there being no reason for a price rise, maybe even less. Heck I can brew my own! And be in spec. The good news is that G100UL, no matter how much 100LL is mixed with it, is still within spec. So changeover is a non issue. Cirrus have already written the approval for the Sr range and the POH amendments. That is confidence with a Capital G
So a lot has come from the humble tuned injector............more than most appreciate, especially T34 owners!
Want to know more come see Andrew Denyer or myself at Ausfly.
Clinton will be lurking here, what you say? Agreed?
Sorry Checkers for the thread drift......I got carried away.
Last edited by Jabawocky; 28th Aug 2012 at 11:43.
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SIT, Ubu SIT........Good dog!
While being carried away (quite rightly) by excitement (or maybe too much O2), Jaba may not have quite got across the key points that Checky was chasing. (or maybe he did & I just wanna wax lyrical)
If you want to go LoP, you first install a multipoint engine monitor which these days are pretty cheap (mine cost $14K fitted in 2002).
Then you get onto GAMI and they will email you a Lean Test protocol. This involves taking off and climbing to a nominal altitude (IIRC it was 7000'), whereupon you set up the power as per the instructions then incrementally decrease the mixture over a period of several minutes, recording the resulting data as you go (pushing the EVENT button works fine).
Once you have got to the point where the engine is no longer producing power, you quit the test, go home, download the data and send it to GAMI. They make up a set of GAMIJECTORS each individually tailored for each cylinder for your engine and send them to you (after you pay of course). You bung them in and do the lean test again. Same deal, download the data and send it to GAMI, they send you any revised injectors you need, you do the test again and all should be good, but they will continue to fine tune your injectors as required until the optimum result for your engine is achieved. Alternatively you can have a local guru like AD sort it, but GAMI worked fine for me.
Contis do respond a bit better than Lycos in general terms, but I was very happy with my IO540 results. They ran cool, clean and happy LoP with no CHT ever above 400.
And two years of JPI data downloads, taken every 20 seconds for some 600 hours of ops, across all EGTs, CHTs, FF, yada yada, demonstrated conclusively that shock cooling is bollocks. Shock heating, on the other hand (ie overtemping through mismanagement or other issues like preignition ) is a sure engine killer.
So Jaba me old, when you coming here for a play? We can talk SERIOUS descent profiles
While being carried away (quite rightly) by excitement (or maybe too much O2), Jaba may not have quite got across the key points that Checky was chasing. (or maybe he did & I just wanna wax lyrical)
If you want to go LoP, you first install a multipoint engine monitor which these days are pretty cheap (mine cost $14K fitted in 2002).
Then you get onto GAMI and they will email you a Lean Test protocol. This involves taking off and climbing to a nominal altitude (IIRC it was 7000'), whereupon you set up the power as per the instructions then incrementally decrease the mixture over a period of several minutes, recording the resulting data as you go (pushing the EVENT button works fine).
Once you have got to the point where the engine is no longer producing power, you quit the test, go home, download the data and send it to GAMI. They make up a set of GAMIJECTORS each individually tailored for each cylinder for your engine and send them to you (after you pay of course). You bung them in and do the lean test again. Same deal, download the data and send it to GAMI, they send you any revised injectors you need, you do the test again and all should be good, but they will continue to fine tune your injectors as required until the optimum result for your engine is achieved. Alternatively you can have a local guru like AD sort it, but GAMI worked fine for me.
Contis do respond a bit better than Lycos in general terms, but I was very happy with my IO540 results. They ran cool, clean and happy LoP with no CHT ever above 400.
And two years of JPI data downloads, taken every 20 seconds for some 600 hours of ops, across all EGTs, CHTs, FF, yada yada, demonstrated conclusively that shock cooling is bollocks. Shock heating, on the other hand (ie overtemping through mismanagement or other issues like preignition ) is a sure engine killer.
So Jaba me old, when you coming here for a play?
We can talk SERIOUS descent profiles
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Jamair.......... I need the world I spin around on to slow down a few radians per second...........you know, the pace you are used to
I really do need to get up there, a mate of mine, one has a really nice RV7A that he purchased recently, IFR, GNS 530, lits of round dials and a D10A, tip tanks with more than 6.5 hours in the FL's 130-150, and TAS155 or a bit faster lower and a bit more fuel, and he does YBAF-YBMA and other ports up there quite a bit for business.
VH-ORF if you see it on the ramp. Go say gooday!
Will need to work out how to get the GSX1250FA into the plane.....so we can do some road rides. How about we get the bike in one of yours....
Your profiles would shock cool me
Speaking of DATA, DATA is the real deal. But this is quite clever and funny!
I really do need to get up there, a mate of mine, one has a really nice RV7A that he purchased recently, IFR, GNS 530, lits of round dials and a D10A, tip tanks with more than 6.5 hours in the FL's 130-150, and TAS155 or a bit faster lower and a bit more fuel, and he does YBAF-YBMA and other ports up there quite a bit for business.
VH-ORF if you see it on the ramp. Go say gooday!
Will need to work out how to get the GSX1250FA into the plane.....so we can do some road rides. How about we get the bike in one of yours....
Your profiles would shock cool me
Speaking of DATA, DATA is the real deal. But this is quite clever and funny!
Last edited by Jabawocky; 28th Aug 2012 at 12:58.
TCM don't seem to be aware of it either.
Crap baffle seals is possibly the biggest cause of bad cooling.
The other one to avoid is increasing the mixture to rich rapidly when in the circuit.
Crap baffle seals is possibly the biggest cause of bad cooling.
The other one to avoid is increasing the mixture to rich rapidly when in the circuit.
Last edited by RVDT; 28th Aug 2012 at 18:03.
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Jamair........ you know you deserve it
VK2....damned that is one thing I can measure. The system logs everything, and I mean everything. It doesn't (coz i have no sensors) measure aileron, elevator and rudder position, but it could. there are spare inputs. no I will not be bothering either. Then you could really see how sloppy I am. But flap and trim it does as it displays these on the EMS, so a flap over speed is detectable
RVDT, Baffles and their seals is a biggie indeed. More than most realise
As for mixture, you are spot on again, in the circuit or at TOD
. Why would you jam the mixture in on descent. The fuel will not shock cool either (popular myth) but it is very wasteful and harmful to the engine. All those nice clean plugs and cylinders from good ground leaning, in flight operation, all messed up coming down. That would be stupid.
A point to note here for those folk who do not fully understand their fuel systems. TCM and Lycoming use different suppliers for fuel delivery (IO) and the Lycoming, which has the Precission or Bendix system looks after the F/A mix as you get into denser air on the way down. Any slight errors, usually gum/dye buildup makes it less accurate so you just tweek the mixture a bee's ...err whisker if it gets a bit rumbly on the way down.
On a TCM (CMI) you have a fuel pump that is coupled to the engine (as is the lyc) but the fuel delivery is proportional to RPM. So you lean against the flow by RPM, so as you descend into denser air, the mass airflow is not affecting the fuel flow, so it needs slightly more tweaking. on the other hand, the TCM with better airflow in the engine will run generally speaking much further LOP on descent anyway, so the problem is off set a little.
Lastly, Carby engines behave like the Bendix / Precission intake, metering against mass airflow, so only tweeks required if necessary.
VK2....damned that is one thing I can measure. The system logs everything, and I mean everything. It doesn't (coz i have no sensors) measure aileron, elevator and rudder position, but it could. there are spare inputs. no I will not be bothering either. Then you could really see how sloppy I am. But flap and trim it does as it displays these on the EMS, so a flap over speed is detectable
RVDT, Baffles and their seals is a biggie indeed. More than most realise
As for mixture, you are spot on again, in the circuit or at TOD
. Why would you jam the mixture in on descent. The fuel will not shock cool either (popular myth) but it is very wasteful and harmful to the engine. All those nice clean plugs and cylinders from good ground leaning, in flight operation, all messed up coming down. That would be stupid.A point to note here for those folk who do not fully understand their fuel systems. TCM and Lycoming use different suppliers for fuel delivery (IO) and the Lycoming, which has the Precission or Bendix system looks after the F/A mix as you get into denser air on the way down. Any slight errors, usually gum/dye buildup makes it less accurate so you just tweek the mixture a bee's ...err whisker if it gets a bit rumbly on the way down.
On a TCM (CMI) you have a fuel pump that is coupled to the engine (as is the lyc) but the fuel delivery is proportional to RPM. So you lean against the flow by RPM, so as you descend into denser air, the mass airflow is not affecting the fuel flow, so it needs slightly more tweaking. on the other hand, the TCM with better airflow in the engine will run generally speaking much further LOP on descent anyway, so the problem is off set a little.
Lastly, Carby engines behave like the Bendix / Precission intake, metering against mass airflow, so only tweeks required if necessary.
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So that explains why the Retard Vehicle was farting like a trooper in the circuit when we last went for a jolly.......it was you playing with your red knob.
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I would be much obliged if someone would post their engine performance graphs for
1/ a max continuous power climb at best angle to say 8000, followed by
2/ cutting the power to idle, followed by
3/ a descent at vne to landing
any takers?
1/ a max continuous power climb at best angle to say 8000, followed by
2/ cutting the power to idle, followed by
3/ a descent at vne to landing
any takers?
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Clinton said
Looking at Jaba's data, that is not the case at all.
The greatest rate of cooling shown is Jaba's idle descent from 6,400ft to circuit height at about 17deg/min (as the oat increased by 19 deg).
What I also found very interesting was the 45 deg CHT decrease at TOC as the RPM was reduced from 2630rpm to 2450rpm with no other changes. Significantly greater rates of cooling (x3) than after shutdown.
It's all in that amazing data presentation.
ps Jaba, is the donk meant to put out 2700rpm at take-off. It looks like you're 40rpm short of perfection if so.
The data show that the highest rate of cooling, and (therefore presumably) the greatest risk of ‘shock cooling’, occurs at shut down. If anyone’s got data to show a greater rate of cooling at any other phase of any other kind of flight, post it please.
The greatest rate of cooling shown is Jaba's idle descent from 6,400ft to circuit height at about 17deg/min (as the oat increased by 19 deg).
What I also found very interesting was the 45 deg CHT decrease at TOC as the RPM was reduced from 2630rpm to 2450rpm with no other changes. Significantly greater rates of cooling (x3) than after shutdown.
It's all in that amazing data presentation.
ps Jaba, is the donk meant to put out 2700rpm at take-off. It looks like you're 40rpm short of perfection if so.
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Give me a break, you mean best rate at least, after all that is what a tug/grass dart plane is asked to do. But if I get a chance one day I will do a best rate and see what I get. The issue is really all about Delta T/min. So if my CHT is 475 not 375 which is normal, well it wont matter what I do at 8000' will it. Besides the ICP's are so low pulling the power, half the problem has gone away!
The point is a conforming engine, with conforming baffles etc, should not be seeing 475-500F anyway. As GB would say, it is hard to shock cool an engine that is already cool.
I did a series of climb tests to gather data for a bunch of interested fellows yesterday none of which were like the ones you mentioned, but using a steady IAS and comparing WOT/MAX RPM/Target EGT Vs doing a WOT/MAX/Full Rich and a 25/25/FR climb like the old wives tails suggest.
Each descent was power pulled and back to 700AGL for a go around and do the next run. CHT's never went below 235-250 on the way down.
Best bit was the climb performance, time to climb and temps, which is what the logging was about. All favoured which method do you think? (Hint: Braly who wanted the data will not be changing his course material)
The point is a conforming engine, with conforming baffles etc, should not be seeing 475-500F anyway. As GB would say, it is hard to shock cool an engine that is already cool.
I did a series of climb tests to gather data for a bunch of interested fellows yesterday none of which were like the ones you mentioned, but using a steady IAS and comparing WOT/MAX RPM/Target EGT Vs doing a WOT/MAX/Full Rich and a 25/25/FR climb like the old wives tails suggest.
Each descent was power pulled and back to 700AGL for a go around and do the next run. CHT's never went below 235-250 on the way down.
Best bit was the climb performance, time to climb and temps, which is what the logging was about. All favoured which method do you think? (Hint: Braly who wanted the data will not be changing his course material
)
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Join Date: Jul 2007
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Trent, I think if I pulled out all the stops and tweaked the little screw, it would but that is hard work, involves lock wire and such.
I like your eye for detail!
I like your eye for detail!