First generation Jet bombers

[davparlr]

I have known someone who was a crew member on a B-45. I was surprised there were any. I don't remember him complaining about the aircraft. He did mention that it had over sized horizontal stabilizers.

Love watching those F-86s fly.

 

[GregP]

Hi Dave,

Come to our airshow this year. It isn't firm as in "set in stone," but I believe we have lined up at least seven P-47's and are trying to get at least three B-17's. Unfortunately those are VERY expensive. The support they require, even just to GET here, is expensive. We'll see.

The Horsemen have been practicing at Chino and the surrounding area in both P-51's and the F-86's, so perhaps they'll make an appearance again, too. If nothing else, their P-51's have been freshened up a bit. Hard to believe it, but the show is only 2 months away. Time flies when you're having fun, doesn't it?

One of our main sponsors this year is Mooney Aircraft! They are back in business and are a main sponsor of our 2014 show. Maybe they'll have a team of Mooneys doing something this year, I don't know.

In any case, be here, Dave! Don't forget the sunscreen.

About the P-59, Bell was told they wanted to get to very high altitude but, without any power numbers, he simply added enough wing to get there. It was a test plane, not ever intended as a fighter. The wing is like a sailplane and the main problem when landing the P-59 is coming down. It wants to float for a LONG way. If you add a few knots to the calculated speed, you'll have a hard time getting to down and stopped in a reasonable distance.

Virtually all the former P-59 pilots who have visited can tell of a time they ran out of fuel and glided to some airstrip 30 - 45 miles away ... sometimes a civilian airport where they had to wait for a truck to drive in with some jet fuel that wasn't avialable locally.

Also about the engines, they didn't tell Larry Bell where the engine mounts were located and he had the plane designed and under construction before he knew where to mount the engines! A lot was left for "later" simply due to secrecy surrounding the Whittle engines. There is a Rube Goldberg tripod that mounts to the wing and is used to hoist the engine into position when installing it through an access door on top of the wing near the canopy. Tightening the engine mounts is not a task for the calustrophobic ... you'll be in some very tight places where your hands and arms can seem quite stuck ... at least MINE seemed that way until I relaxed and thought about it.

And if I don't have to climb into the rear fuselage again for anything, it'll be too soon for me. That hurts because there is nothing to step on untl you hit the bottom of the fuselage bulkheads. We reskinned one aileron and are 85% along with the other one. When that is done, we are down to systems checkout and making an instrument panel. Not much left before final checks and then flight test.

Right now we're fighting with two flat tires. Both main tires went flat and finding tubes for that size tire is not without some bloodhound work. They don't exactly grow on trees.

And we have yet to find a good way to seal the rear of the sliding canopy ... so there are still some interesting times left in the project.

 

[razor1uk]

When I 1st saw an XP/P-59 3 view diagram, much of its general design remind me strongly of a P39/63 fuz with the engines mounted below the oversized wings against the lower fuz.

With the engines likely hanging off the heavily adapted old central engine frames/structures, and a lengthened rear fuz with a scaled up P63 tail.

I think, Bells manufacturing experiences and the availability of ready components in stock to build with, untilising them to quickly produce the planes.

I wonder how close my gut reaction is and how similar the 59 is to the earlier 39's 63's Greg/guys if it is ok to ruminate upon?

(sorry, a little hopefully appreciated mis-direction from the topic)

 

[GregP]

It is very similar to a "Big P-39" in concept and structure.

By the way, after reading my post above it sounds like I'm tooting my own horn about working in the fuselage ... but it's really the opposite. The rest of the guys are too big to get in there so I lost the lottery and was forced into it. In reality there are about 6 regular guys and 2 - 3 others who occasionally work on this thing ... and we all want to see it out of the restoration hangar and on display. After twenty-two years on it, many of the volunteers are pretty anxious about the whole thing and want to see it fly or at least to go away for awhile. If things go as we THINK they will, it'll be making positive strides toward flight quite soon.

They want it out on the ramp at the airshow in May, so it's about time to stop work and button it up for the show. The rest of the weekends between now and May are pretty much completing annuals for some of the birds and doing pre-airshow maintenance for infrequent flyers.

The P-47 is one that doesn't fly frequently, but takes a lot or work for an annual. Since we're having some six or seven P-47's show up for the show, ours needs to be ready, too. That should be a real sight to see ... some B-17's with a pretty complete P-47 escort ... B-17's, P-47's, a couple of P-38's and several P-51's all in one flight. An ETO-type USAAF flight there.

 

[BiffF15]

GregP,
Great video's! Thanks for posting those. I have seen a few of the Horsemen videos but never in the Mustang / Lightning combo or the Sabers. You mention that the P-38 had a new engine and the demo wasn't good for it. Is there some break in procedure that is being "pushed" by their routine? I really liked the 3 ship formation takeoff (have never done one of those) in the F-86s but noticed that the lead aircrafts engine smoked noticebly less. Do or did they not all have the same kind of engine or is it a different type of fuel? I've flown with F-4's and they were quite smokey (as were the Mig-29s) but didn't expect such differences between aircraft as the F-86s had.
Keep the pictures and videos rolling in, they are great!
Cheers,
Biff

 

[GregP]

For all WWII V-12 engines I know of, the break-in procedure for a newly-rebuilt engine (assumes fresh cylinder liners and new piston rings, fresh valve seats, fresh valves, new bearings, etc.) runs about the same.

The Allison V-1710-90/100 series all have a 3,000 rpm max and usually a max of 57 inches of manifold pressure for normal operations. If you are a "war emergeny guy" you can use up to 75 inches MAP. Nobody is running early Allisons. Even the guys with the P-40B and C models are running -80 / -90 / -100 series Allison engines mated with the early nose cases, and they have to consiously use only the allotted amount of power the nosecase can handle.

1) It is best to run straight oil and a club prop or real prop. We did it with straight 90 weight oil and a 6-blade club prop.

2) You start the engine and let it idle until it is running smoothly at something like 800 rpm or so.

3) Once running smoothly, advance to 1,000 rpm and let it idle until the temperature gets warm. That means an oil temp of maybe 85 - 90°C and continuous good oil presure. Look for leaks other than the test stand. There is usually minor seepage that quits as things warm up and seat in.

4) Once warm, slowly advance to 1,600 rpm and let run for about 5 minutes on the test stand. Monitor temp and oil presure for good values the entire time. Look for leaks.

5) Shut it down, clean the engine, clean the screens and engine stand oil filters looking for anything other than tightseal (used to seal the gaskets). The cuno will have a lot of tightseal on the screens, so clean it up and clean the engine stand filters. Reassemble things. What you are looking to do is seat the piston rings. You must run the mixture at auto rich to start it (don;t HAVE to but works well), but you then lean it until the engine gets the smoothest. It sounds hard but isn't once you see it done or do it yourself several times. The exhaust flames tell the whole story and the ques to look for are well desvribed. Any veteran can help you out there. Mainly, avoid backfires. These can and WILL blow out gaskets requiring breakdown. Not usually, but it CAN happen.

6) Always start and idle until warm. Change rpm very slowly. No WWII V-12 likes to accelerate or decelerate quickly. If you have the habit of accelerating or decelerating quickly, your engine life will be half of what it should be or less.

7) Once warm run it up to 1,600 rpm slowly and run for about a minute at 15 - 20 inches MAP. Then advance to 2,000 rpm and maybe 20 - 25 - 30 inches of manifold pressure. Look for the exhaust stacks to turn a unifiorm dark grayish brown/black. If the color is uniform and the mixture is right, the rings and valves are seated. Continue running until almost seated as fuel and temperature allows. Look for leaks and clean the engine. ANy leaks should be MUCH less or gaone, or there is a problem thaht needs to be adressed. Better hope you paid attention when you installed the gaskets and seals.

8) Clean the cuno and oil filters every hour or so to check for what is moving around in the engine. You should see lessening amounts of tightseal and no silver material. Tiny silver is usually bearings (lead or silver from the mains) and irregular bits can be broken rings. After maybe 4 - 6 hours, the tightseal will stop and the cuno should be clean or almost clean after an hour of running. That is what youa re looking for. You can now run it until broken in before cleaning the screens and filters again, but do that when the engine is ready to ship so the customer gets a freash engine ready to run. If it is in the plane, you are ready to fly.

9) Once the exhaust stacks are uniform, start and warm the engine, advance to 1,600 rpm, then to 2,000 rpm for about a minute, then to 2,300 to 2,500 rpm or so and up to 35 to 37 inches of manifold pressure. Run for several minutes, temperature permitting.

10) Once the rings are seated you can do a short run to 2,500 rpm and maybe 35 - 40 inches or so. It depends on the prop used and the pitch. Can't do that too long or the test stand starts moving. Joe's test stand is a Ford dually truck and he can pull it backwards if he uses too much power. With a good club, you can load any V-12 so it can't get past 1,500 rpm, so the trick is to set the pitch. With a 6-blade Hamilton-Standard club, the correct pitch is about 23.5° or so, depending on model. With that we can get 2,500 rpm at 45 inches on the test stand. After seating, the owner usually wants to see a run or two and learn to start it and adjust the mixture himself / herself, and it's time to do that once the rings are seated. Sometimes they don't and we'd drain it, disassemble the test stand setup, and seal the engine for shipment. We leave oil in it so the owner doesn't have to pre-oil the engine unless it sits too long before use. Pre-oiling isn't tough, but you DO need the tools.

They are easy. Get a small 5 - 10 gallon air tank and fill it with oil about 3/4 full. Pressurize it and insert the hose onto the oil intake galleys. Use air pressure of about 70 psi or so and let the oil flow with the valve covers off until oil comes out the heads all along the cam area. Re-install the valve covers, clean the seepage, and it is pre-oiled and ready for startup.

11) Once in the plane, Joe would offer to come check it out and make sure the connections were correct. He would also offer to start it and warm it up for the new owner.

12) Once ready for flight, the proedure is similar to a test stand run at first. Start it and let it warm up so the oil is at 90°C or better. The taxi out and fly. Set the prop to fine pitch, which gives 3,000 rpm once in governing range.

13) On takeoff, roll onto the runway and SLOWLY advance to 45 inches, Let the plane accelerate to 45 - 55 knots and slowly advance to 50 - 57 inches. Lift off and climb for about a minute. Reduce to 35 - 40 inches or so and pull back to 2,100 - 2,500 rpm (we recommend 2,200) and cruise it around at low and medium power (600 - 850 HP or so, maybe 900 HP), occasionally going to 45 - 50 inches for a minute or so, until the bearings are thoroughly broken in. This usually takes anywhere from 15 - 20 hours. Once broken in, you can pretty much run it like you want as long as you warm it up gradually, advance AND retard the throttle slowly. If you are flying a P-38 DO NOT use the engines for steering on the ground and pay atention to the cylinder head temps. Forgetting to open the radiator doors after landing can toast an engine(s) on the ground taxi back to the hangar. Think of them as a single engine planes and use the brakes for steering. If you throttle-jockey the engines to ground steer your P-38, your main bearings will have a short, unhappy life ... they do NOT like quick acceleration to make a sharp turn. It is MUCH better to slowly accelerate the plane and use brakes for the sharp turn than it is to use throttle. Brkaes are WAY cheaper than Allisons, particularly the left hand turn Allisons. The P-38 and the sole Il-2 in Paul Allen's collection are the only planes that use a left turn Allison.

If you follow these steps, you can get a long happy Allison life (or Merlin life). Oil changes and maintenace come at factory-recommended intervals. WWII engines like to run frequently rather than sit for a year and then run. If you can't fly it at least a few hours a month, preferrably an hour a week, don't own one. Carburetors need overhaul every five years at a cost of around $5,000 each. If you can't afford that, don't own one. Mags sometimes fail; plugs sometimes foul or fail, and distributors sometimes develop issues.

If your old wiring harness is more than 10 years old, get Joe or someone else to rewire it. Cracked ignition wires are a chief cause of rough running and ignition missing. Buy a few spare and learn how to install them correctly or have someone do it who KNOWS how to do it. WWII spark plugs are antiques. If you have WWII plugs, make them into a display ... but don't run them in your engine. Run new plugs. They may be $30 each or more, but if you can't afford good plugs, you can't afford to run an Allison or Merlin.

By following these procedures and a few others, Joe Yancey has several customers with 1,100+ hours on their Allisons and they are still running smoothly and well.

If you are running a Merlin, you have to do normal Merlin maintenance. You do NOT have to check the cylinder liner torque on an Allison but you re-torque every 25 - 30 hours for a Merlin. That's not a knock on a Merlin, just a different procedure to follow due to the design of the engine. Each one has many "special tools," and each one has its positives and negatives. Both will give good service if you treat them right, fly regularly, do the maintenance, and don't abuse them.

Abused warbird engines can get VERY expensive instead of just expensive.

If you think V-12's don't like to accelerate or decelerate quickly, radials are even MORE sensitive to that behavior. They really like to run at a steady speed and steady power setting. Abuse an R-3350 and it might bite you in one flight. Treat it well and it can last 3,000 hours between overhauls.

The R-2800 is about as tolerant of abuse as any radial in the world. Treat a good one of those right and it will last a LONG time. Even the R-1340 in a T-6 / SNJ rewards gentle treatment with longer life. Of course, any radial will also oil down the engine compartment, belly, wheel wells, and lower sides of your plane ... but anyone who flies a radial knows that and accepts it. If they mind a bit of oil, they don't need a warbird, because all will reward you with oil as you run them. It's like a cat bringing you a dead bird or animal ... it goes with the territory.

It helps to own a rag factory.

If you abuse an engine too soon, it usually means a new set of main bearings, and that means engine removal and breakdown. Don't DO that. If you do, you will regret it, at least in the wallet, if not in flying time.

 

[blueskies]

Thanks for helping me understand the problems that beset Bell in building the P-59. I have been very critical of this design and its very poor performance compared to the German designs. I have felt there were problems with the intake but it looked okay. Being too big makes a lot of sense. Not only would it affect drag but possibly thrust efficiency. I also feel the wing size, 60% greater than the Me 262, which grossed out 50% heavier than the P-59, was also a major contributor to its poor airspeed performance. I suspect the airfoil is also a generation behind the German jets, and, the contemporary P-51.

P-59 had a naca 66 series airfoil, same series as the P-51H.

 

[BiffF15]

GregP,

Excellent information and thanks for sharing! I had no idea that the break in was such an involved process. In paragraph 6 you mention that the WW2 V-12's didn't like quick accel or deccel. Did they adhere to that in combat or was it do what you need to survive / win and we will take care of the motors as required? Did they have a fairly short TBO in combat? I understand that today they are treated gently to get max life out of them.

In para 13 you mention a 15-20 hour break in period. I'm assuming this wasn't done in WW2, and if not how did they handle break in's back then?

Cheers,
Biff

 

[GregP]

In WWII the WAAF's and other production test pilots slow-timed the birds so they would be broken in right, here in the USA before line delivery. They pretty much adhered to good practices stateside except for young hotshots ... but most of THEM were away at the front lines. In combat if there was a scramble and you did what was necessary. And many P-38 jockeys didn't pay any attention to the crew chiefs or the training and operated them as they saw fit, thereby creating "war weary" engines well before their time.

Generally, even in the Luftwaffe and Japanese air arms, the crew chiefs would start the birds early in the morning and warm them in preparation for the day's activities. If they didn't fly (but were fit to), they were warmed periodically throughout the day in anticipation. They tried very hard to operate the engines right but, in combat, you did what was required at the time. You can be sure they paid close attention to engine operation on an escort mission as they had the time and weren't going anywhere fast anyway. If they got bounced, then they usually went to combat power almost immediately as quickly as possible as part of a necessary survival reaction.

WWII engines never reached wear-out. They were shot down, failed, or ran until overhauled at anywhere from 250 - 450 hours whether they needed it or not, usually back in depot maintenance areas set aside for aero engine overhaul (speaking of Allisons and Merlins ... not all V-12's). This was a "military overhaul" and they were pretty good at it. Sometimes they did a front-line overhaul that was usually new piston rings and maybe a few other top end cylinder bank items, but rarely did they do main bearings in the field, though it was certainly possible if the need was pressing.

Today owners want good engine life and pay attention. One way to know is when the oil pressure drops. If it is normally at 75 pounds per square inch and falls to 65 psi for some reason, with everything else being normal. you can bet the mains are at fault. The crankshafts are hollow and are oil pressurized, with small weep holes in the bearing journals for oiling the mains in operation. There was supposed to be a certain clearance, and that made the crankshaft operate on a thin film of oil under pressure. If the clearances get too big, then the oil shoots out into the open space and the oil pressure drops a bit. When it gets to certain limits, you KNOW it is time for mains. You can continue to operate it if you want, but you are playing with your life.

Merlins had different limits and limitations, but were generally similar, being of similar material and design. They, too, either failed, were shot down, or operated until time for the prescribed military overhaul.

You were always supposed to overhaul and engine when it received a prop strike, but sometimes this was bypassed. Sometimes they got away with it and sometimes they didn't. Bypassing safety precautions is never a good idea and can frequently be a very BAD idea. I'd rather be down here wishing I was up there than vice versa.

 

[razor1uk]

Some great mechanically sympathetic and very apt instructions there Greg in abstract ways, they apply to all combustion engines - if you wring it, it'll fling it (or your wallet, you or all three).

 

[tyrodtom]

When I was at Nakhon Phanom, RTAFB in 1967-68, most of the aircraft there were radials .
T-28, A-26, A-1E&H, and Navy P-2s.

They didn't have a lot of spare hanger space, so you could see the big sealed canisters they shipped and stored the engines in were kept in a dirt field near the flight line. Those canisters themselves probably cost a $1000 even then.

But you could tell when the aircraft had had a engine change and was being slow timed, it wouldn't be on regular mission status, unless there was a emergency. ( like someone shot down) If you saw a A-1 taking off with nothing on the wings, it was most likely being slow timed. Just a local flight, or maybe flying someone to a conference at another base in Thailand. If you were near the runway, it was obvious they were using less than normal takeoff power; they were lightly loaded, but still used a lot of runway.

The only time I saw the B-26's flying in daytime, was when they were being slow timed.

 

[Shortround6]

US aircraft engines in WW II were run for a few hours at the factory (2-6 hours?) depending on engine type/factory/time period while connected to a load. One or more factories had them connected to electrical generators and powered a good amount of the factory while test running/breaking in the engines. 20-30 R-2800s running generators at the same time can make a LOT of electricity
Engines were partially torn down for inspection then reassembled and often (always?) run again before being preserved and packed for shipment.

I don't know what other countries did. Engines were monitored for temperature, oil and coolant flows and inlet and outlet oil and coolant temperatures and power output at certain RPM and manifold pressures. ANY engine not meeting specifications was torn down and inspected/rebuilt and tested again before shipment.

This run/test was not a full break-in but at least gave the engine a 'start'.

 

[GregP]

Yeah. They had the advantage of many test stands (that were not on wheels). I believe the procedure for breaking in radials is different, but you still need to seat the piston rings and ensure the exhaust stacks get a uniform dark gray black color, while not producing flames from the center of the stack that indicate rich or lean running. The flame you must see is very specific ion color, shape, and length.

For that, I'd assume they had individual exhaust stacks for break-in, and not a collector ring like many radials eventually had in end item use. I'm assuming they also had the radial tets stands mounted in what would amount to a wind tunnel so they could be cooled. AIr-cooled engines need a lot of air to cool.

 

[davparlr]

The best book I have is titled "Flame Powered" by David M. Carpenter. I found my copy on ebay for very little money.

Ordered the book. Thanks for the info.

 

[oldcrowcv63]

US aircraft engines in WW II were run for a few hours at the factory (2-6 hours?) depending on engine type/factory/time period while connected to a load. One or more factories had them connected to electrical generators and powered a good amount of the factory while test running/breaking in the engines. 20-30 R-2800s running generators at the same time can make a LOT of electricity
Engines were partially torn down for inspection then reassembled and often (always?) run again before being preserved and packed for shipment.

I don't know what other countries did. Engines were monitored for temperature, oil and coolant flows and inlet and outlet oil and coolant temperatures and power output at certain RPM and manifold pressures. ANY engine not meeting specifications was torn down and inspected/rebuilt and tested again before shipment.

This run/test was not a full break-in but at least gave the engine a 'start'.

As a young engineer, circa 1970, on my first job, I had frequent occasion (on my way to the jet engine test cells) to walk down a corridor lined with Curtiss Wright's reciprocating engine test cells. The Recips, which I assume were the big turbo compounds, always seemed to be running, apparently 24/7 and the noise was near deafening. These engines tests being performed some 25 years after the end of WW2, but of course the engines were still being used in a variety of aircraft, military and civil. I never heard that they were providing power for the company. As far as I know they were running unloaded. But of course absence of knowledge (ignorance) does not translate to absence of the application.

At the time I was involved in a project to convert the CW J-65 (license built Armstrong Siddeley (RR) Sapphire) into a commercial gas turbine for a variety of applications. The most interesting of these apps (from the perspective of the assigned test engineer) was its use as a compressor to feed snow blowers at NJ's Great Gorge ski area. Fun times!

 

[Shortround6]

The engines had to connected to a "load" in order to get power measurements and to keep the engine from "running away". In some cases it was a short bladed but heavy "dummy" prop called a test club.

In other cases it was a dynomometer. It could be hydraulic or electric.

Certainly not every every engine factory used the test engines to generate electricity but at least one did.

Proper testing was beginning to be understood even at the end of WWI

http://www.airforcemag.com/SiteColl...rticle Images/2008/February 2008/mccook05.jpg

 

[GregP]

At Joe Yancey's we used a 6-blade test club with adjustable pitch. You adjusted them manually and carefully. Mostly we were at 22 - 23° any more pitch and you could keep the Allisons (or Merlins) from spinning more than 1,500 rpm. We needed 2.000 - 2,500 and 35 - 40 inches for brief bursts and mostly were at 1,500 - 2,000 and 20 - 25 inches for break-in.

Before we got the 6-blade, we used a 4-blade and the pitch had to be a lot higher. Joe still has the 4-blade.