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Then tell us what that is with regards to maintaining large radial engines???
In the field working on a military aircraft, (and this goes back to WW2), there is a specified amount of maintenance and preventative maintenance a crew chief can do to their aircraft. If one tries to do any modifications or make adjustment outside of maintenance manual parameters, that individual could get themselves in a lot of trouble, especially if an incident or accident occurs as a result of not following maintenance guidelines.
The "really competent" maintenance crew chief who went back to the states after the war found themselves working for the airlines and more than likely in a supervisory role.
There is much more to keeping a squadron of planes serviceable every day for military operations than keeping a drag racer fit for quarter mile runs when and where you feel like doing them.There's more to keeping a very highly tuned engine on the top line than just swapping the plugs.
Especially if the air group is conducting several sorties per day.There is much more to keeping a squadron of planes serviceable every day for military operations than keeping a drag racer fit for quarter mile runs when and where you feel like doing them.
I also have issues with the term "higher state of tune". WW2 aero engineers could have upped the power massively if they engine only had to run for 8 seconds. Producing thousands of engines that had high power outputs and ran for 6 hours without stopping and 250 hours between overhauls is the difficult part.Especially if the air group is conducting several sorties per day.
I put that in the same category as a "worn out engine" with no detailsI also have issues with the term "higher state of tune". WW2 aero engineers could have upped the power massively if they engine only had to run for 8 seconds. Producing thousands of engines that had high power outputs and ran for 6 hours without stopping and 250 hours between overhauls is the difficult part.
If you could use a dragster as a runabout family car and do a standing quarter in six seconds I would be impressed, to me a dragster is just in a different state of tune, it doesnt last long enough to get off the ground in an airplane. I think I said on that thread, most times I heard that it was to do with the whole plane not just the engine.I put that in the same category as a "worn out engine" with no details
"WORN OUT ENGINES"
Hoping to get some input from some of our resident engine experts (ShortRound6, GregP, Tomo, MiTasol, Bill M and Calum, to name a few, I know there's more). I've seen many publications (and some posts on here usually referencing another source) making references to "worn out engines," or "tired...ww2aircraft.net
I have seen the equivalent of drag racing in planes - STOL Drag Racing. (If you haven't seen it, its a thing) The top competitors in that category fly planes that are good for 10 seconds of max thrust, but not for actually cruising around. The event consists of two planes in parallel drag racing to take-off and then coasting/slide slipping to a landing about 1000ft turning around and doing the same thing in reverse. The first to come to a complete stop at the starting point wins. The guy who won at Reno this year was flying a Carbon Cub outfitted with a modified Jet Ski engine and a four bladed sea plane prop.If you could use a dragster as a runabout family car and do a standing quarter in six seconds I would be impressed, to me a dragster is just in a different state of tune, it doesnt last long enough to get off the ground in an airplane. I think I said on that thread, most times I heard that it was to do with the whole plane not just the engine.
Yep but quite different from military operations.I have seen the equivalent of drag racing in planes - STOL Drag Racing. (If you haven't seen it, its a thing) The top competitors in that category fly planes that are good for 10 seconds of max thrust, but not for actually cruising around. The event consists of two planes in parallel drag racing to take-off and then coasting/slide slipping to a landing about 1000ft turning around and doing the same thing in reverse. The first to come to a complete stop at the starting point wins. The guy who won at Reno this year was flying a Carbon Cub outfitted with a modified Jet Ski engine and a four bladed sea plane prop.
Thanks FLYBOYJ,Yep but quite different from military operations.
Most, if not all of those aircraft are flying under an experimental airworthiness certificate thus they can legally do lot's of tweaks to their engines and airframes.
Exactly! And many times that "middle of the "range" was set in AAF TOs.He needed to keep the engine in the middle of the "range" so the engine would run without stalls/stubbles/ misfire. etc when the engine was running at 8;00am taxing out over a British dew and ground fog morning or running at 10:00AM at 30,000ft 300 miles to the east.
I would actually disagree with that statement. The requirements for production, street engines are radically different from one-off engines for hot-rods or street racing. Neglecting the need to produce them in hundreds or thousands (or, for automobiles, tens or hundreds of thousands) of near-identical units, there is the need to have vast quantities of spare parts quickly at hand.I think we would agree that street and drag racing post WWII greatly accelerated improvements to automotive/engine technology and perfomance - but they weren't doing their magic on the flight line. That said, Crew Chiefs, as Joe noted, were focused on making sure to the best of his ability that all systems on His ship were in the green when he handed it off to the pilot for a mission... and to the specs in the manual.
When discussing aeroplanes normally I expect the aircraft to fly higher than the Wright flyer and leave the airfield.I have seen the equivalent of drag racing in planes - STOL Drag Racing. (If you haven't seen it, its a thing) The top competitors in that category fly planes that are good for 10 seconds of max thrust, but not for actually cruising around. The event consists of two planes in parallel drag racing to take-off and then coasting/slide slipping to a landing about 1000ft turning around and doing the same thing in reverse. The first to come to a complete stop at the starting point wins. The guy who won at Reno this year was flying a Carbon Cub outfitted with a modified Jet Ski engine and a four bladed sea plane prop.
Here's a video link to see what it looks like:
The 'really competent crew chiefs' were the guys who went back to the States after the War and founded the huge US hot rod and tuning scene.
I believe I do.You do not know how to read the Operating Tables for Range with and without 75 gal tank.
I believe I do.You do not know the definition or operating parameters for translating maximum operating range to Combat Radius planning assumptions.
Sure I do.You do not read the footnotes with respect to a.) using 16 gal of internal fuel for Warm Up, T.O. and climb to 5,000 feet, b.) using 20 gal of internal fuel for Warm Up, T.O. and climb to 5,000 feet with 75 gal tank.
Sure I do. That's why reserves for combat and landing are deducted from the range for a combat mission. Otherwise it is a ferry mission as described in the table.You do not read the fine print for zero reserve calculation in the Range Table.
You are correct about the 690 miles at 15000' but that column is for max range cruising, not combat. The left column of the chart (max continuous power) shows that the P-39Q will cruise at 25000' with a drop tank. Range in this column can be deceiving since the posted range figure is is only good at or below 12000'. Obviously burning a tank of fuel at 25000' (62 gallons per hour) will result in a much longer range than burning the same tank of fuel at 12000' (107gph).You do not seem aware that only one line exists for 20K altitude none for 25K altitude and that the max Range calc for 75 gal external is 690miles - at 15K, not 20K not 25K at a cruise speed of 170 mph IAS. BTW the TAS of the 15,000 foot flying P-39 for maximum RANGE is slower than B-17s flying 10,000 feet above the P-39Q.
The Flight Operation Instruction Chart (range chart) certainly does include a reduction in range to account for the climb from 5000' to 25000' as I explained above. The burn rates you quote are at 12000'. At 25000' the burn rates are substantially lower (109gph vs 62gph for max cont. power). Use the military and combat power burn rates for the 20 minute reserve for combat. They have no place in the range calculation unless you are calculating combat range or radius. Then you would deduct the combat reserve and landing reserve along with the 20gal takeoff/climb reserve from the total fuel load.The Operating Range Tables do Not include the fuel consumption for climb from 5,000 feet (at Max Continuous) to 15, 20 or 25K. Max Contnuous Power burn rate for the V-1710-89 is 109gph. Military Power is 138gph, Combat Power is 170gph. Even assuming Table Values for Military Power at 138 for Combat at max radius (i.e. no WEP at 170gph for 5 min),you have to subtract 138/3 for 20minutes=46 gal.
P-39Q (with drop tank) used 20gal reserve for takeoff and climb to 5000', 26gal for 20 minutes combat at 25000' and a 10gal for 20min landing reserve (32gph for 20 minutes). So for a combat mission deduct 56gal reserves from total fuel. The combat reserve is calculated as follows: military power is 1.27 times max continuous (138gph vs 109gph) at 12000'. At 25000' fuel burn is 62gph at max continuous x 1.27 = 79gph at combat power, 20 minutes would be 26gal. All from the P-39Q handbook.So, independent of cruise leg that P-39Q assigned escort duties for 25K, a.) uses 20 gal from Warm Up to 5K, b.)approximately 10minutes at Max Continuous Power to climb (clean) from 5K to 25K (source Dean AOHT) = 109/6 = 18gal, c.) 46 gal Combat at max radius d.) 20 minutes Reserve to find home base and land at Min Cruise Power (42gph/3) = 13. (source for a., b., c. and d P-39Q Handbook),
Nope. Only 56gal in reserves is deducted from the total fuel available. 20+26+10. Climb from 5000' to 25000' WHILE HEADING TO THE TARGET was already figured in the tables. Drop whatever tank you are carrying and there are still 120gal internal less the combat allowance of 26gal and the landing reserve of 10 gal for a net after reserves of 84gal. Quite more than 23gal.Of your 120 gal of internal fuel (you don't switch to external tanks until cruise altitude) you must subtract
20+18 + 46+ 13 gal =97 gal of your internal fuel Not used to cruise to and from the target to Let Down to find your base. Assuming your 75 gal tank could conceivably complete leg to Target and Combat (VERY Bad assumption), that leaves you with 23 gal (optimistic, no provision for flying formation, etc).
Nope. Like I said above after the tank is dropped there are still 84gal internal after reserves. At 62gph there is still 1.35hrs at 330mph (cruise without drop tank) or 445 miles. After reserves.Get out yer sliderule kid, show me what you get in straight line RANGE at 25,000 feet flying minimum fuel burn rate of 42gph with 23 gallons of fuel at approx 170IAS (optimistic) at 25K. That 'Leg' is your Combat Radius.
I don't think so. Like I said above a P-39Q with drop tank cruised at 267mph at 25000', well above the cruising speed of the B-17. For reference the P-47 cruised at 285mph with a drop tank. As to the LW destroying all available P-39s, how did that go with the Russians? They did pretty well with the P-39, shot down more Axis planes than any other American fighter. Of course they removed the underwing guns on the P-39Q, ordered most of them that way from the factory.And BTW, the P-39Q can not fight anything useful at 25K, much less keep up with B-17/B-24 fully loaded. The LW will destroy all available P-39s in inventory in a couple of missions and the 8th AF will finally be able to use the P-47, P-38 and P-51 unmolested by P-39 acolytes.
My Bad.
Didnt we have 200 pages of this on another thread? Believing isn't quite enough in a technical discussion.I believe I do.
I believe I do.
Sure I do.
Sure I do. That's why reserves for combat and landing are deducted from the range for a combat mission. Otherwise it is a ferry mission as described in the table.
You are correct about the 690 miles at 15000' but that column is for max range cruising, not combat. The left column of the chart (max continuous power) shows that the P-39Q will cruise at 25000' with a drop tank. Range in this column can be deceiving since the posted range figure is is only good at or below 12000'. Obviously burning a tank of fuel at 25000' (62 gallons per hour) will result in a much longer range than burning the same tank of fuel at 12000' (107gph).
Example: At 12000' the 145 available gallons of fuel (after deducting the 20gal takeoff allowance) divided by 107gph gives 1.3hrs at 298mph TAS = 387mi. The chart shows 365mi reflecting the reduction for climb from 5000' to 25000' that is built into the chart to make it easy on the pilot.
Example: At 25000' the 145 available gallons of fuel being burned at 62gph gives a flight time of 2.3hrs at 267mph TAS = 614mi. Reduce that by the reduction for climb from 5000' to 25000' of 30mi and range is 584mi at 25000'. Substantially more than the 365mi at 12000' on exactly the same tank of fuel.
BTW the P-39 flying at minimum power at 15000' was slower than the B-17 at 25000' (221mph vs 225mph) but the B-17 was flying at a much higher power setting (max continuous power). At 25000' the P-39Q with a drop tank cruised at 267mph TAS which was faster than a B-17 cruised at that altitude. What's your point?
The Flight Operation Instruction Chart (range chart) certainly does include a reduction in range to account for the climb from 5000' to 25000' as I explained above. The burn rates you quote are at 12000'. At 25000' the burn rates are substantially lower (109gph vs 62gph for max cont. power). Use the military and combat power burn rates for the 20 minute reserve for combat. They have no place in the range calculation unless you are calculating combat range or radius. Then you would deduct the combat reserve and landing reserve along with the 20gal takeoff/climb reserve from the total fuel load.
P-39Q (with drop tank) used 20gal reserve for takeoff and climb to 5000', 26gal for 20 minutes combat at 25000' and a 10gal for 20min landing reserve (32gph for 20 minutes). So for a combat mission deduct 56gal reserves from total fuel. The combat reserve is calculated as follows: military power is 1.27 times max continuous (138gph vs 109gph) at 12000'. At 25000' fuel burn is 62gph at max continuous x 1.27 = 79gph at combat power, 20 minutes would be 26gal. All from the P-39Q handbook.
Nope. Only 56gal in reserves is deducted from the total fuel available. 20+26+10. Climb from 5000' to 25000' WHILE HEADING TO THE TARGET was already figured in the tables. Drop whatever tank you are carrying and there are still 120gal internal less the combat allowance of 26gal and the landing reserve of 10 gal for a net after reserves of 84gal. Quite more than 23gal.
Nope. Like I said above after the tank is dropped there are still 84gal internal after reserves. At 62gph there is still 1.35hrs at 330mph (cruise without drop tank) or 445 miles. After reserves.
I don't think so. Like I said above a P-39Q with drop tank cruised at 267mph at 25000', well above the cruising speed of the B-17. For reference the P-47 cruised at 285mph with a drop tank. As to the LW destroying all available P-39s, how did that go with the Russians? They did pretty well with the P-39, shot down more Axis planes than any other American fighter. Of course they removed the underwing guns on the P-39Q, ordered most of them that way from the factory.
Didnt we have 200 pages of this on another thread?
Funnily enough I am just reading a book on the P-51B ( a Christmas present) something about a Bastard Stepchild, anyway in discussion on pre war US aircraft the P-39 gets a couple of paragraphs from the 63 pages I have read so far, the main point being it wasnt as fast as advertised.I guess the Corsair was a new version of the P-39 Groundhog.