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Originally Posted by Australopithecus
(Post 10599494)
The gear is electrically operated on the B-17, and quite slow compared to hydraulic gear on more modern types. I don’t believe that the aircraft could climb much on two engines regardless of the gear position, |
That is why I stated my comment at at the end but thanks for your post b1. Will add something here...
In general I just can´t imagine any flight crew leaving the gear down - on purpose - with an Eng failure during T/O. One wants to climb and also prepare for the unexpected. It is also a requirement for the second segment climb. (Do not know if that applies to the B-17) No, I frankly do not think they lost number 3 engine (if they did) because of leaving it with high power. Engine was new and the data shows a descend what, 3 min after T/O at the most ?? |
Originally Posted by WING7
(Post 10599815)
That is why I stated my comment at at the end but thanks for your post b1. Will add something here...
In general I just can´t imagine any flight crew leaving the gear down - on purpose - with an Eng failure during T/O. One wants to climb and also prepare for the unexpected. It is also a requirement for the second segment climb. (Do not know if that applies to the B-17) No, I frankly do not think they lost number 3 engine (if they did) because of leaving it with high power. Engine was new and the data shows a descend what, 3 min after T/O at the most ?? You really do have to appreciate how slowly the gear retracts,( one wheel at a time due to electrical load). It may be that the crew were initially planning a different course of action. I do know that when flying these national treasures you are doing everything that you can to not damage them. A belly landing wouldn’t feel like a good outcome, so perhaps trying for a perfect result might have been a factor. |
Rightly so Austral, unfortunately it may have been a factor.
The maintenance aspect before the flight and then having problems in flight could also have added pressure. Who knows. |
Quote: “How slowly the gear retracts” It did so on the WW2 era aircraft I first got my left seat as airline pilot. Here is a link for the flight manual of the EAA B-17 if anyobody is interested. https://www.eaa.org/~/media/files/eaa/flight%20experiences/safety/b-17-flight-training-manual.pdf It’s good to have more engines but for the new aviators here, the more you have of course the more chances of loosing one and sure it happens so!! |
Later WWII recips required high octanes that are no longer available (unless you special order a refinery batch).
With lower octanes you have to reduce manifold pressures to prevent detonation and consequently get less performance. That said, I don't know the octane requirements for the engines on the B-17. |
Originally Posted by RatherBeFlying
(Post 10601648)
That said, I don't know the octane requirements for the engines on the B-17.
https://cimg5.ibsrv.net/gimg/pprune....0b365505af.jpg |
Originally Posted by RatherBeFlying
(Post 10601648)
Later WWII recips required high octanes that are no longer available (unless you special order a refinery batch).
With lower octanes you have to reduce manifold pressures to prevent detonation and consequently get less performance. That said, I don't know the octane requirements for the engines on the B-17. |
I've worked on the DC3, DC6 and An2 (Asz621R engine copy of the Curtiss Wright R1820 Cyclone fitted to the B17) and they've all operated on 100LL Avgas. I can't remember the max manifold pressure of these except for the DC3's R1830, which was 48").
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Are octane ratings from the 1940s directly comparable to modern ones? The octane rating depends on the test used (e.g. the numbers are different for the same mogas in the U.S. and Europe), so the scale might have changed at some point after the war. Or it might not have.
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Originally Posted by Chu Chu
(Post 10601951)
The octane rating depends on the test used (e.g. the numbers are different for the same mogas in the U.S. and Europe)
There are 2 tests and thus 2 number Resesrch and Motor Octane Number (RON and MON) UDA used the average of the two. That's why the sticker in the pump says (R+M)/2. Also call AKI, anto-knock index Europe uses just one, RON. 93 AKI (UD) ~ 98 RON (most of the world) |
Originally Posted by Chu Chu
(Post 10601951)
Are octane ratings from the 1940s directly comparable to modern ones? The octane rating depends on the test used (e.g. the numbers are different for the same mogas in the U.S. and Europe), so the scale might have changed at some point after the war. Or it might not have.
https://generalaviationnews.com/2007...130-and-100ll/ |
Have the NTSB confirmed anything about the aircraft configuration--engines operating, gear, flaps during the entire traffic pattern? I've wondered how often the pilots of old warbirds do any simulated engine failure training, which (most of us know) would need to be done Far above traffic pattern/circuit altitude.
They will probably take months before saying anything, waiting for the full investigation's results. It's so nice to be retired from the career! I only miss the hand-flying up to FL 200 or the many hand-flown approaches and landings. Retired on the B-717 (MD--). |
Originally Posted by Ignition Override
(Post 10602021)
It's so nice to be retired from the career! I only miss the hand-flying up to FL 200 or the many hand-flown approaches and landings. Retired on the B-717 (MD--).
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My airline chapter lasted 43 years. Loved it but its so nice to sleep at night and fly during civilized hours. |
Mogas and Avgas "Octane" numbers do not equate exactly, the test methods are different. However, this is moot, the B-17 was not and should not run Mogas. 100LL (blue) and 100/130 (green) are both 100 octane where it matters. 155/145 (purple) is long ago not available. If there were a concern about inadequate octane rating of the Avgas for an engine which was built to use 115/145, reducing a combination of power, duration at power, and temperatures could restore detonation margin. If in doubt, run the engine at a faster RPM, and lower MP, rather than the other way around (don't lug the engine) and it can tolerate lower octane, particularly for a brief time. Certainly, if I were flying a MP limited engine(s) and needed the power to prevent crashing, I'd push the throttles further forward. It might detonate, it might not - to save the plane, it's worth the risk, though you might be replacing some pistons afterward.
100LL Avgas should be the same worldwide. Mogas not so, different by different national standards, and often has stuff other than "gasoline" blended in. I have conducted detonation testing on a Continental 470, 520, and Pezetel engine, and succeeded in making the engines detonate, and measuring the event. I did it without damaging any engine doing the testing. That said, I only detected the detonation by my measurements, and watching engine temps very closely, I could not tell that detonation had begun by "feel" or engine noise, nor smoothness/performance. Once I had detonation, I immediately reduced power to stop the detonation. Interestingly, the detonation continued for seconds after the power was greatly reduced. I would never fuss the maximums and risk detonation in service, other than to prevent an immanent crash. From this testing, I found the manufacturer's maximum operating limitations to provide conservative detonation margins. Cesar Gonzales, who did a lot of detonation testing for Cessna told me that Cessna melted pistons and trashed engines occasionally during their testing. |
We did not need the simulated Eng. failure practice on the old aircrafts because of having so many for real. ;)) |
Technically you can't have an Octane rating above 100, anything beyond 100 is called a "Performance Number", though Octane has been adopted by the community for anything beyond 100 by way of convenience. You can see that in the attached chart, the lean rating is given as Octane and the Rich rating as Performance Number.
https://www.exxonmobil.com/english-U...XXAvgas-Series |
"Are octane ratings from the 1940s directly comparable to modern ones?"
Yes. The equipment used to determine the ratings was designed in the '30s and '40s. The same basic designs are used worldwide today. Only one manufacturer is authorised, Waukesha. There are Russian copies I believe but I've never seen one. 100LL and 100/130 is essentially the same spec and can be interchanged. The only difference is 100LL has Low Lead, ie. less TEL added made possible by using higher octane blendstock to achieve the same octane performance i.e. 100/130. The 100 bit refers to minimum 100 MON (usually around 103-104 MON on the stuff I tested) while the 130 refers to minimum Performance Number of the fuel tested on a supercharged version of the MON engine (usually around 132-132 P.N.) |
Originally Posted by megan
(Post 10602066)
Technically you can't have an Octane rating above 100, anything beyond 100 is called a "Performance Number",
For the motor octane number when you reach 100% isooctane you cant of course mix more isooctane. I’ve heard the ”Performance number” before but as often Ive also heard octane numbers above 100. |
Another factor to consider is that Mogas vaporises much more readily than Avgas, as used to be demonstrated by pouring a thimbleful of each on a concrete floor. An even better demonstration is to prove how easily it vaporises in an ultralight fuel pump during a long climb with no electric pump backup. I still have the scars from the ensuing forced landing :ouch:
Always sad to hear of any accident particularly when this should have been a joyous and much anticipated aviation occasion. My sympathies to the families of those who lost their lives. |
"For the motor octane number when you reach 100% isooctane you cant of course mix more isooctane"
By definition the octane rating of isooctane is 100. Both 100 RON and 100 MON, with RON meaning Research Octane Number and MON - Motor Octane Number. These tests are done on 2 different types of Octane engine. The MON rating of a particular fuel is always lower than the RON rating of the same fuel. This is because the MON method is a harsher test on the fuel than the RON method. There are plenty of fuels that have an octane number greater than 100, both MON and RON. By "fuel" I'm not meaning necessarily commercially available fuels but any hydrocarbon that can be successfully run on the laboratory internal combustion engines. "I’ve heard the ”Performance number” before but as often Ive also heard octane numbers above 100." Octane numbers refer to fuels tested on normally aspirated laboratory engines (F1 or F2) while Performance Numbers refer to tests performed on a supercharged laboratory engine (F4 engine). So 3 different types of tests, 2 types of Octane number, 1 Performance Number. All 3 can be greater than 100. Performance Number - always, MON - always for Avgas, not for motor gasolines, RON - never for regular commercial fuels (Avgas is not tested on the RON engine but it would be higher than 100) but Toluene for example is over 120 if my memory is correct.. |
I’ve heard the ”Performance number” before but as often Ive also heard octane numbers above 100 https://cimg9.ibsrv.net/gimg/pprune....52c12e2ec5.jpg |
Originally Posted by megan
(Post 10602773)
As I said, for ratings above 100 the community has adopted the word "Octane", but technically it's not correct. Octane rating of a fuel is one that has the same knock characteristics of a particular mixture of iso-octane and heptane. 90% iso-octane and 10% heptane has an octane rating of 90. Pure iso-octane ie 100%, has a rating of 100 octane. With a fuel that has better knock characteristics than 100% iso-octane they obviously had to come up with a means of quantifying the knock rating, hence the "Performance Number". As you can see from the chart both lean and rich ratings are given as PN ("Performance Number") because both are above 100, though they seem to have transposed the rich and lean numbers. Once again, technically 100 is as high as an octane rating can go. I must emphasise the word technically ie the petroleum industry, not community common usage.
https://cimg9.ibsrv.net/gimg/pprune....52c12e2ec5.jpg Perhaps I wasn't clear enough in my previous post. The 100/ 130 bit in Avgas 100/ 130 for example refers to 2 different test results using 2 different engine types. The 100 number is an Octane number in this case a MON (Motor Octane Number) obtained by testing the fuel on a MON engine, method ASTM D 2700. The 130 number is a PN (Performance Number) determined on a F4 Supercharged engine, method ASTM D 909. The 2 engines are quite different, the methods are very different as are the results. One is an Octane number, one is a Performance Number. When running a MON test on an Avgas sample the result is always over 100 because the 100/130 bit refers to a minimum spec of 100. The reference fuels over 100 required for the test are prepared by adding TEL (tetra ethyl lead) to isooctane. There is an error in that Shell info sheet. The method is ASTM D 909, not 910.. |
Hey posters, are we good with the discussion about octane rating on this thread now? Good discussion, though a little off topic here. We can do a separate gasoline thread if you like, good info, but probably not really relevant to this accident...
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An interesting Liberty Belle cockpit overview by one of the B-17 pilots - dated 2011 but a couple of interesting points
1) Landing gear 45-50 seconds to fully retract or extend 2) Significant drag from cowl flaps - sometimes used to assist in trimming/turning the aircraft as in high crosswind. 3) Lands fine with flaps retracted 4) Good discussion on the prop feathering buttons and relationship to pitch control - interestingly mentions that in the event the prop feathering system failure for an engine out, pitch control was the only option to turn the blades at least partially. Curious that he would mention prop feathering failiure in discussion of pitch levers. Several posts on other sites indicate feathering problems or inability to feather engines on the early G models due to the removal of the oil tank standpipe as part of weight saving measures. I have not been able to confirm and no source given. Anyone? |
Originally Posted by Pilot DAR
(Post 10603506)
Hey posters, are we good with the discussion about octane rating on this thread now? Good discussion, though a little off topic here. We can do a separate gasoline thread if you like, good info, but probably not really relevant to this accident...
Cheers, Grog |
I posted a B-17 training film from the 40’s. Im pretty sure the instructor tells the trainee to limit manifold pressure as they’ve “got 92 today”. |
In one of the videos the pilot mentions that the guy who put the throttle levers the way the are on the B-17 should be hung up and I agree. Wonder if it was the same guy who put the mixture levers with rich in the aft position. Hope they pull the cord 1mm/day once its tense.
LG switch, geeee. Putting all 4 feathering buttons together. Better separate left from right wing ones like on the DC-6 and others I feel. Must have been a very good aircraft to do its job but the cockpit controls deserved a better design/set up. |
I suspect an overwhelming majority of the 400 hour pilots that flew the B-17 in combat didn't have an issue with the cockpit layout, considering it was the only four engine aircraft they had ever flown.
The throttles were designed that way to provide simultaneous control of one side or of all four engines in one movement. Adjustments had to be made often to keep the aircraft in the tight combat box formation. |
Originally Posted by ThreeThreeMike
(Post 10604307)
I suspect an overwhelming majority of the 400 hour pilots that flew the B-17 in combat didn't have an issue with the cockpit layout, considering it was the only four engine aircraft they had ever flown.
The throttles were designed that way to provide simultaneous control of one side or of all four engines in one movement. Adjustments had to be made often to keep the aircraft in the tight combat box formation. The good thing is that it raised investigation and evolution. -- QUOTE control of one side Guess you meant outbord or inboards. Don´t recall having any problem flying formation with the DC-6 using its ergonomic throttle levers setup |
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No a nice reading ..
My sincere sympathy to the families of the B17 crew of that flight when they will be reading this PS : .I am not forgetting the families of the pax that died in that accident , but the difference is they they wanted and expecting a special experience when boarding that flight because it was out of the ordinary and flown by enthusiasts and volunteers. Sometimes **** happens in those conditions , No-risks heritage flying does not exists. . |
I wonder what the maintenance discrepancies were. That could be a big issue if they were significant and especially if they led to the accident.
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Originally Posted by tcasblue
(Post 10728912)
I wonder what the maintenance discrepancies were. That could be a big issue if they were significant and especially if they led to the accident.
As someone that has flown with Collings on 2 occasions some 10+ years ago, the report details makes sad reading. |
Originally Posted by tcasblue
(Post 10728912)
I wonder what the maintenance discrepancies were. That could be a big issue if they were significant and especially if they led to the accident.
Condition and Limitation No. 6 states as follows: Collings must maintain all aircraft subject to this exemption in accordance with the— a. Collings General Maintenance Manual; b. Maintenance requirements as specified in the appropriate type specification sheet, as amended; c. FAA-approved maintenance inspection program that meets the requirements of § 91.409(e), (f)(4), and (g); and d. Appropriate military technical manuals. Inspection of the engines on the B-17G N93012 established magneto and ignition failures existed. Regarding engine 4, to prevent the magneto “P” leads from separating from the magnetos, someone had attempted to rig the magneto leads in place with safety wire. Inspection and testing of engine 4 left magneto revealed the movement of the safety-wired lead caused grounding to the case, which rendered the magneto lead inoperative. In addition, the right magneto of engine 4 was found unserviceable. The cam follower was worn beyond limits and the point gap was less than half the measurement required by service documents. When tested, the magneto produced weak or no spark to four of the nine cylinders. All spark plugs were inspected and required cleaning and all electrode gaps were out of tolerance; therefore, further engine inspection indicated signs of detonation and associated damage. An inspection of engine 3 showed all spark plugs electrode gaps were out of tolerance, fouled, and revealed various signs of detonation. Further inspection of this engine revealed problems with the cylinders. As a result of these findings and other information, the FAA questions whether the engines were inspected adequately and in accordance with the applicable maintenance requirements. The discrepancies noted above indicate maintenance, or lack thereof, occurred in a manner contrary to maintaining aircraft in accordance with the General Maintenance Manual (GMM). The GMM incorporates by reference inspection procedures for individual aircraft, as described the Aircraft Maintenance Manuals. See General Maintenance Manual Rev. 1.1 at 19 (Sept. 10, 2017). Moreover, the records memorializing the inspections and maintenance performed on the B-17G lack key information and, in some cases, indicate maintenance was either not performed at all or was performed in a manner contrary to the applicable requirements. See Ground Check Inspection Form #15: Accessory Inspection, Engine Number Four Fourth (25 Hour) (Sept. 23, 2019); Ground Check Inspection Form #17: Ignition System Inspection, Engine Number Four Fourth (25 Hour) at ¶¶ 11-13 (Sept. 29, 2019). In addition, maintenance records indicate the removal of wires and no further repairs or adjustments, even though a wire was burned and arcing. See NL93012 B-17G Flying Fortress Flight Report (May 11, 2019). The same record, as well as a record from the following day, indicates flights with passengers occurred in the aircraft. See id.; NL93012 B17G Flying Fortress Flight Report (May 12, 2019). As a result, Collings did not fulfill the requirements of Condition and Limitation No. 6. |
Thank you for this information. Very interesting and also concerning. I find the information that the pilot in command was also the Director of Maintenance most concerning as presumably he is and was responsible for all the other aircraft within the maintenance organisation. An unacceptable conflict of interests in my opinion . I have been a director of maintenance here in Canada and cannot imagine ever being in this position.
very sad. |
Originally Posted by WING7
(Post 10604535)
Make no mistake TTM, those pilots had throuble with the cockpit layout and controls. Raising the gear instead of the flaps upon landing is a biggie.
The good thing is that it raised investigation and evolution. -- QUOTE control of one side Guess you meant outbord or inboards. Don´t recall having any problem flying formation with the DC-6 using its ergonomic throttle levers setup It was because of the study of many aircraft mishaps, including B17 gear selection mistakes, which lead to changes in cockpit design and the birth of ergonomics.One result was control selector standardisation,landing gear selector with a wheel shape and flap selector with an aero foil section. |
Originally Posted by ATC Watcher
(Post 10728886)
I am not forgetting the families of the pax that died in that accident , but the difference is they they wanted and expecting a special experience when boarding that flight because it was out of the ordinary and flown by enthusiasts and volunteers. Sometimes **** happens in those conditions , No-risks heritage flying does not exists.
. I have flown in the B17 Fuddy Duddy several times and I have to say that not once on any of these occasions, regardless of a/c type, did it ever occur to me to consider anything as banal as insurance. I agree with ATCW; people who subscribe to these flights generally regard them as an adventure which, by definition, involves the excitement of something daring or potentially risky. If they wish to remain totally safe (and "totally" is relative!), they should stay in the car park and give up their seat to someone prepared to accept and enjoy these flights for what they are. Of course, I'm not condoning improper maintenance or operational procedures, but those are different subjects. |
Originally Posted by Gipsy Queen
(Post 10729172)
I have flown as pax in many heritage aircraft and am sufficiently heritage myself to have piloted some of them commercially, years before they became "heritage"!
I have flown in the B17 Fuddy Duddy several times and I have to say that not once on any of these occasions, regardless of a/c type, did it ever occur to me to consider anything as banal as insurance. I agree with ATCW; people who subscribe to these flights generally regard them as an adventure which, by definition, involves the excitement of something daring or potentially risky. If they wish to remain totally safe (and "totally" is relative!), they should stay in the car park and give up their seat to someone prepared to accept and enjoy these flights for what they are. Of course, I'm not condoning improper maintenance or operational procedures, but those are different subjects. |
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