B17 crash at Bradley
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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 ??
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 ??
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 ??
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.
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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.
The maintenance aspect before the flight and then having problems in flight could also have added pressure.
Who knows.
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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.
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.
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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.
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").
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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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)
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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.
https://generalaviationnews.com/2007...130-and-100ll/
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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--).
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--).
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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.
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.
)
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
https://www.exxonmobil.com/english-U...XXAvgas-Series
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"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.)
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.)
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.
