F4U in Europe (2 Viewers)

[DerAdlerIstGelandet]

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.

Not just that, but imagine if a mission was not made because unapproved repairs/mods were made.

As you know mechanics just don't go doing whatever the heck they feel like. Repairs and mods have to be approved. It's not like you are working on a car that can be pulled over on the side of the road.

 

[pbehn]

There's more to keeping a very highly tuned engine on the top line than just swapping the plugs.

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.

 

[GrauGeist]

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.

Especially if the air group is conducting several sorties per day.

 

[pbehn]

Especially if the air group is conducting several sorties per day.

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.

 

[FLYBOYJ]

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.

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

 

[pbehn]

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

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.

 

[NevadaK]

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 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:

 

[FLYBOYJ]

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.

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.

 

[NevadaK]

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.

Thanks FLYBOYJ,

I was trying to reinforce the point being made that engine tweaking for hot rodding and maintaining operations of high performance aircraft are not the same.

 

[Shortround6]

Very few crew chief's had access to temperature chambers/pressure chambers when on front line squadrons or the instruments the engine manufactures did.

Crew chiefs could do a lot of things in WW I with biplanes that they could not do in WW I.


Hot rodder's rarely had to take temperatures at thousands of feet in different altitude or at places hundreds of miles away on the same day.
A good hot rodder could adjust the carb's for the best possible "tune" for a morning speed run and tweak it later for a mid day run.
A crew chief couldn't do that. 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.

WW II aircraft engines by the end of WW II were some of the most highly stressed and highest performance engines that could be found. There were no easy 'tweaks' to be found despite what some crew chiefs (both US and RAF) might have thought. Ununortized changes

A P-38L with Allison engines in late 1944 was operating under quite different conditions than a P-38 in 1942. And the engine internals had quite different changes. Different piston rings, different valve springs (even though the valve timing was the same and the valve clearance was the same) the engines were operating at up 70in MAP using 150 PN fuel in Europe.

 

[FLYBOYJ]

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.

Exactly! And many times that "middle of the "range" was set in AAF TOs.

 

[swampyankee]

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.

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.

 

[GregP]

As for "worn-out" engines, I have seen several times that the TBO was set NOT so the planes would not have worn-out engines, but rather that at least 97% of the engines returned for overhaul had engine block that could be used again for the overhaul process. I have also seen the actual percentage number vary by ±1 or 2 %, but the intent was to have "rebuildable" engines, not to run them until the blocks had to be replaced instead of being overhauled.

By way of example, the Allison engine company only made pistons / cylinders in nominal (fits a 5.500" bore), .010 over (fits a 5.510" bore) and .020 over (fits a 5.520" bore). There were no other pistons / cylinders available from Allison. If a cylinder could not be cleaned up for use with a 5.20" bore, then the cylinder was replaced with one of nominal, .010" over, or .020" over.

Today, a well-built Allison V-1710 should run easily for 700 - 1200 hours, mostly trouble-free. In WWII, they were overhauled at anywhere from 250 - 500 hours, depending on the calendar year. TBO got longer as they got the engines tweaked better and had more experience with them. Ditto, Merlins, radials, and whatever. Same held true for early turbojets. Early units had little life. Today, turbines last a LONG time.

The only piston engines I know of that is not routinely overhauled are some diesels. When they get to their service life, they are simple replaced with new or used units and are then scrapped. They can be repaired, to be sure, but when the engine life is reached, they are basically shot. Many have a LONG life, making that a reasonable choice.

 

[pbehn]

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:

When discussing aeroplanes normally I expect the aircraft to fly higher than the Wright flyer and leave the airfield.

 

[wuzak]

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 thought the origins of hot rodding lay in the prohibition era.

 

[GregP]

I KNEW it would get around to alcohol!

 

[P-39 Expert]

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.

I believe 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.

You do not read the fine print for zero reserve calculation in the Range Table.

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 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.

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 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.

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.

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),

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.

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. 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.

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.

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.

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.

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.

My Bad.

 

[pbehn]

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? Believing isn't quite enough in a technical discussion.

 

[DerAdlerIstGelandet]

Didnt we have 200 pages of this on another thread?

I guess the Corsair was a new version of the P-39 Groundhog.

 

[pbehn]

I guess the Corsair was a new version of the P-39 Groundhog.

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.