Whats the deal with Soviet Wing design?

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Want to sit in a P-51? I can help you do that, and maybe get a flight. They smell like fighers ... not necessarily gasoline. The cockpits are full of the smell of old leather, warm electronics, sun-baked paint and bakelite, etc, plus maybe some pilot sweat ... hard to describe but, once you sit in one, you can't mistake the smell of an old warbird. They are all similar with the radials smelling a bit more oily.

About the old engines corroding, I can give you an example. Joe Yancey came across some old Allisons that were formerly used in Hydroplanes. The owner was the wife of a late racer (20 years ago). She had left the Allisons sit out in a field, no plugs in them, unclosed coolant openings, in the weather. They had gone through at least two floods where they were under water for a month or more.

None would turn over when a 10-foot long pipe was attached to prop wrench, even when we put oil for 2 days into each cylinder. That has a few connotations ...

The only pistons approved for aircraft use in a V-1710 by the factory manual are nominal, 0.10" over, and .020" over. The rings will compensate for up to 0.010" of egg-shape. So that means if any of the cylinders are pitted deeper than .027" or so, the liners are shot. The water jacket had water in it for 20 years and had rusted through in a couple of places on 3 of the 4 Allisons, so the blocks weren't any good and the 4th one was probably very close to coming through, too. A pressure test probably would have burst it, maybe not. The cams and were rusted enough to be useless. We never saw the crankshafts, but you can bet they were bad, too, along with the rods.

That means we could probably hydraulic the pistons out once the cams were off (maybe not if we couldn't get the valves closed with a dead-blow hammer against the srpings), but the pistons, liners, rods, and probably the wrist pins were going to be pretty much not usable except for maybe a museum cutaway ($10,000 easily). A cutaway doesn't fly. The cases were shot.

The nose case might have been OK, but the very necessary nosecase bearings probably were too far gone to be recoverable ... you'd have to disassemble it to find out. I do not know the condition of the accessory case and the supercharger. Two of the engines had fallen over and had broken the carburetor and carb mount off the accessoriy cases, so the cases were no good either. The carbs looked like the surface of the moon from Earth.

So maybe we could use assorted nuts and bolts, the valves, valve guides, maybe 1/3 of the valve springs, the valve spring washers retainers, some nuts and bolts but not all, the intake manifolds, probably all the studs, MAYBE the intake rubber pieces (maybe not), the gaskets that seal the valve covers and maybe a few more, perhaps the cam towers and tachometer drive, and accessory plates. That ain't much when you consider a V-1710 has about 7,000 parts. OK, we could probably use all the crankshaft plugs and oil galleys and a few minor but necessary pieces, too. Maybe the mags were overhaulable, maybe not.

The woman wanted $20,000 each and was quite distressed to hear that we pay very much less than that for an engine that turns over, and $200 - $1000 for one that doesn't turn depending on condition. Hers were so bad that Joe wouldn't offer even $500 each. There were that many parts ruined.

Here's the thing ... there are only about 4 - 5 shops in the world that can do a GOOD rebuild of these old Allisons. I'm not too sure about Merlins, but the good Merlin shops in the U.S.A are few and we probably mostly know them in this forum. Only these guys know what to do with old parts to make them serviceable, if possible. To anybody else, the engines are scrap metal. You can't buy a core that turns over from ANY of the shop owners for $5,000 because they are worth $90,000 - $250,000 (depending on mfg model scarceness) or more when overhauled and sold after break-in to an aircraft owner. So why in the name of heaven would anyone sell you one for pennies on the dollar unless he was desperate? None of the owners of the Allison / Merlin overhaul shops are desperate. If he saves it, perhaps it can be overhauled and sold at a later date.

If you are smart,and if there's nothing else going on in the shop, you take the old cruddy engines apart in slack time, recondition the parts to where they are suitable for overhaul, and put them into "overhaulable stock." When you can't make money, it's time to at least stock up on things that will sell when someone wants an engines built from parts. It happens, and usually on SHORT notice, and you either react or lose the money. If you can't react and if you have a pile of old, disassembled engines ... it's YOUR fault. The parts are only sellable when the condition can be seen.

The amount of oil and crud on the engine has nothing to do with it ... it's the internal condition that counts. In fact, the more old, dirty oil and grease on it, the better the condition will be when it is cleaned up and refurbished.

Perhaps you will get an idea when I get some Zero pics this wekend. You can compare the before and after.

These aren't engine parts, but you can see a very noticeable difference between the pics, and it should be obvious why the overhaul was needed.

It is much the same with engines. I'll get a shot of an old Japanese engine recovered from a beach on Yap and post that, too. You should be able to see the issues with overhaul easily.
 
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It is much the same with engines. I'll get a shot of an old Japanese engine recovered from a beach on Yap and post that, too. You should be able to see the issues with overhaul easily.

Great post Greg, in principle aluminium resists corrosion to most things however salt water attacks it as any owner of a motorbike knows. For old engines, they are full of many types of metals, normally these are separated by oil, once allowed to dry and water to get in they set up corrosion cells and start to eat each other on the galvanic scale. I havnt seen it in an old Aero engine but have seen a couple of triumph bikes with exhausts off in a field, just junk really.
 
I know that when Chevrolet revamped their L-6 engines (194, 230) and introduced the L-4 (153) in 1960, they were using a cast aluminum thermostat housing that bolted to a cast iron base, which in turn was bolted to the cast iron head.

Over time, the coolant passing through the brass radiator, cast iron components, cast iron waterpump (with steel vanes) and then through the brass and copper thermostat would eventually "pit" the interior of the thermostat housing by way of electrolysis to the point of failure. In some cases, these housings failed in about 5 years, most started failing before 10.
 

I've always thought it strange that even newly-restored WW2 aircraft have that smell.


And we've bene on the receiving end of this stocking up. Less than 24 hours after locating a Griffon magneto, we had it down here, and the aircraft flying and delivered to the customer.

Couldn't agree more with the external vs. internal condition statement. Some of the best internal condition of engines that I've seen in storage have been from engines that have looked pretty horrible on the outside. I think that oil-soaked dirt and dust must act like a preservative.
 
That's why outboard motors have the dissimilar trim tab that looks like a small rudder just above the prp. It is supposed to corrode instead of the Aluminum outboard engine and transmission and lower unit. Maybe some of you have had to change these, even in fresh water?

One of the interesting things in ownership happens when they put a few pieces of steel into an otherwise-Aluminum airplane that YOU own with Aluminum rivets (or steel rivets). That is dissimilar metal and unless it is carefully prepped painted/sealed, will eventually corrode both the rivet and the hole in the steel ... and bleed over into the Aluminum-to-Aluminum part, too. The hope is you get enough use out of the aircraft structure before that happens. Landing a seaplane in salt water greatly accelerates this corrosion process and, once you DO land one in salt water, the process of complete destruction of the aircraft starts and you WILL lose your airplane sooner or later. How well you control it will determine how much "later" that is.

You can imagine the crud control procedures that have been accomplished by the operators of the last Martin Mars that started life in WWII and that have gone on since it was launched. It's probably as bad or worse than engine maintenance. I'd guess worse.

Probably FlyboyJ knows for sure.

Hi gumbyk,

After being around it a bit, I think you are right ... oil-soaked dirt IS a great preservative. So it's probably against the law somehow. But it happens anyway when you let an old, oil-soaked engine sit around in the elements.

Here is a WWII pulsejet as we found it in the Planes of Fame junkyard atfer sitting around since 1957:



Here are close-up:



and here the cowling we metal-spun for it:

 
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And here is a pic of the same engine setup taken earlier this year:



You can see the discoloration from running it (ordinary paint), but the condition should hopefully apparent from the pics above. The control panel and gas tank, as well as all OTHER parts except the rubber diaphragm in the fuel controller, are exactly the same units as above when we found it ... we just restored them.

We made a mold and molded the rubber diaphragm. It took a year and maybe 8 tries to get it to start. After that it was much easier.

All it needs to run again is an overhaul of the fuel pump motor. When we quit running it the pressure was fluctuating to the point of slightly erratic running.

In practice in WWII, the pressure didn't fluctuate as it was delivered by shperical tanks of compressed air.

Here it is pushing my truck down the runway in our 2009 airshow:

View: https://www.youtube.com/watch?v=KTv7dfs_Mlc

First we started it at idle power, then transitioned to full pwoer, then released the brakes. I had my friend Bob,who was driving, keep it under 35 mph because I didn't want anybody to either get hurt or buy a new truck. It ran about one minute and 15 seconds before the temperature got to 1,100°F and we shut it down to save the reed valves. By that time we had passed the entire airshow crowd. You can't tell from the video, but you could hear it for 10 miles around.

The team was Robin Scott, Bob Velker, and Me, Greg Pascal. Robin was the major contributor to the overhaul and Bob and I did a bit of restoration, helped figure out how to start and run it, and helped with the cowling and trailer restoration. Robin had maybe 3 years in it. Bob and I had maybe 1.5.

Unfortunately, Robin recently passed away. We miss him.

Bob and I are thinking about overhauling the fuel pump and running it again ... sort of a tribute to Robin, when we get the time.
 
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If you Google "Chino pulsejet" you can see some videos as we progressed. We took a video of one night run and it is somewhat interesting, but the files show up in here as the wrong file-type. They run fine on my PC screen.
 
That was you guys?!?!

I've got a bit of a soft spot for these engines - I want to build one down here - preferably around 75% to go with our scale model. Get the idea?

Would it be easier to run it on compressed gas? AFAIK these will run on anything, and using a pressurised fuel would eliminate the fuel pump issue.
 
I've always wanted to fool around with a pulsejet, too...

Anyway, here's a couple sites I've been checking on, great info and some really cool applications (especially the jet-cart in the first link)!
Pulse Jet Engine and then a page that's Argus specific: Argus V1 Pulsejet

Pulse Jet Engines | How To Make A Pulse Jet
 
What is it that makes it sound like it does?
The combustion process which basically is a series of explosions, one right after the other in a resonant chamber that controls the amount of combustion per cycle. As the exhaust gases expand and thrust out the back, the next portion of feul entering is ignited by the exiting gases and ignites, starting the cycle over again.
 
The pulsejet would be easy to make except for a few items. The critical part is the reed petals. Our engine is from a US Navy JB-2 Loon, which was a US copy of the V-1. Our engine is about 3/4 the size of the German engine and still makes good thrust.

It sounds the way it does because, as ably said above, it is a series of explosions. First, assume the engine is running. OK ... you get one explosion. The shock wave extends forward and aft. When the forward wave hits the reeds, they snap shut, cutting off the shock wave and reflecting it backwards. When it does, a negative pressure is created and it draws in more air and fuel mixture behind the shock wave. Meanwhile the other shock wave heads out the exhaust end and, when it hits the end of the expansion chanber (tapering part of the pipe), there is a discontinuity since the pipe tapering stops, and some of the shock wave is reflected back in the forward direction, just like in a tuned exhaust on a 2-stroke motorcyle. When it hits the incoming reflected wave from the closed reeds with the accompanying air-fuel mxture just behind it, that mixture is ignited and the process begins all over again.

We checked our pulsetjet by recording the sound and anlyzing the resulting sound waves. Ours resonates right about 43 Hz. That is down in the low-frequency range and that type sound travles a LONG way before dissipating. It is above the hearing threshold of 20 Hz, but not by much. Believe me, when you are close to it, it resonates in your chest cavity (even if you happen to be Dolly Parton). If you have ever been to an American NHRA Top Fuel drag race, you KNOW about sound that resonates in your body ... it's the main reason people go who aren't driving. Top Fuel anything is kick-butt.

Anyway, we installed a calibrated spring against a screw stop and put the other end against a force cylinder that we had around. The engine runs at two levels of power. When you start it, it is in idle mode. When you get it into full power mode, the sounds almost doubles in intensity.

Before we installed the cowling we spun from Aluminum, the thrust came in at about 380 pounds while the engine was at a standstill. The cowling smoothes the airflow into the intake and we never expected it, but simply installing the cowl changed the thrust at full power while still at a standstill to 440 - 450 pounds. We figure it must be due to the airflow having a smooth surface to follow into the reeds instead of a square opening with no smoothing ... les turbulence at the intake.

Anyway, when we ran the engine down the runway, my friend Bob was driving and I was operating the engine control box. Robin worked the controls on the engine itself to help it start when I made the right moves on the control box. Once it started in idle mode, Robin pushed the fuel controller down to get it into full power mode, locked it down with a screw knob stop, switched off the 90 psi airflow, and sat down on the trailer. After we made it up to about only 35 mph (I had Bob use the brakes to keep us from going any faster), the thrust showed at about 550 pounds!

I don't know if traveling at 350 mph would increase it much more, but I'd imagine so. I decline to predict the end thrust at 350 mph based on only 2 runs at 35 mph.

On Saturday they made us run down the main runway. When we didn't die from explosions, they let us run it down the taxiway on Sunday. That was about half as far away from the spectators as the runway was. We heard later that everyone could feel the vibrations in their bodies. Some were outright shocked and some a bit panicked, never having experienced it before.

Steve Hinton was in the cockpit of a fighter (Tigercat at the time) that was only about 30 feet from the taxiway and he said it felt like nothing he'd exerpienced before. We think that may be due to the frequency ... 43 Hz being lower than normal jet engines or drag race Top Fuel engines ... or any other engines we know of.

So the real issue is to make some steel reed valve petals that will bend when required while still being hard enough to withstand the heat. We only have a 3.3 US gallon gas tank and the engine at full power burns about 3.5 gallons a minute (2.2 gallons per minute at idle). So our run timne was only 1 minute and 10 - 20 seconds depending on the fuel level and how long we were at idle before going to full power. We set a self-imposed limit of 1,100°F to try to keep the reeds from "going away" quite as quickly as they otherwise might. In real life the reeds were wearing out just about as the V-1's went over London or very slightly farther. After that the steel reeds would fail one at a time until the engine no longer could function. That's how we captured some V-1s nearly intact ... the vane anemometer system on the front (little propeller-looking thing) probably failed somehow and the V-1 just flew until the reeds failed and it glided in without ever triggering the fatal dive or arming the warhead. Alternately, maybe it ran out of fuel before triggering the dive.
 
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You can see the tapering of the expansion chamber type cone in the pic below. We managed to capture ONE frame of a pulse coming from the pipe:



You can see that one pulse is just about to dissipate and the next one is JUST coming out of the exhaust. We don't know if that is as long as the first pulse got because we only have this ONE frame of the event. But the length is very close to twice the distance from the spark plug (used only at startup) to the reed assembly.

That's Robin in the picture (someone had to take the pic, and that was Bob ... I'm off the right side of the pic at the end of the white control cable that goes to the control box). Robin's boat and Yak-52 are in the background.

As you can see, this was when we were learning how to run it. We had not yet made the cowling or restored the trailer, and were not going to put much more effort into it unless we were successful in getting it to run ... which we managed to do after over a year and a half of trying to re-invent the WWII pulsejet without the advantage of a manual of any sort.

We DID have some "manuals" for hobby-type pulsejets, but they mostly mnake noise, are poorly designed, and are usually about 10% the size of this one ... and ostly run on propane. This one makes useful thrust on 87-Octane unleaded gasoline and was fairly optimized for the type engine it is. I'm sure they could improve it today ... if anyone were really interested in pulsejets, but they certainly wouldn't pass any airport noise regulations! Just ONE of these could wake the dead some miles away. I shudder to think of an airliner with 8+ of them ... bigger units. The crew probably wouldn't survive the noise and the entire town would think the dreaded Russian hordes were attacking enmasse.

I said "Russian hordes" because the aircraft in the background above is a Russian Yak-52 ... so don't be offended if you happen to be Russian. Send Vodka and we'll be your friend. We'll trade you some Levi's jeans and maybe a belt.
 
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The guy in the first link has come into a bit of close scrutiny from national security organisations. He claimed that he could build a cruise missile for under $5k, and was planning on a proof of concept to demonstrate it.


Making petal valves (the ones shaped lie a flower) isn't really too much of a problem - you can electro-etch them out of thin spring steel. but the array system on the Argus looks quite a bit more work to perfect.
 
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I said "Russian hordes" because the aircraft in the background above is a Russian Yak-52 ... so don't be offended if you happen to be Russian. Send Vodka and we'll be your friend. We'll trade you some Levi's jeans and maybe a belt.


LMAO on that one
 
The issue comes with how thin and of what exact material to make the steel petals. Just any old thin sheet steel won't necessarily work. It has to allow bending at just the right pressure and flow. It is possible that the right combination would be easy to find ... and it is possible it would take years.

There are any number of guys who can make pulsejets. We found one guy in Oregon (at the time) who claimed to be the world's expert on them. He wanted decent money to help us, so we just did it ourselves. He told us we'd NEVER get it running without his help. I'll admit it took more than one case of beer and one large Pizza to make the thing run, but it wasn't insurmountable.

The thing is to have a test plan that methodically goes through the variables until you get a pop. Then you know you're close. Once you get the first pop, you're usually not more than 10 - 15 tries away from a start. Our big issue was NO pop until we tied compressed air at 90 psig. Then we puzzled for about a month on how to get it up to full power from idle and not blow out the rubber diaphragm with the 90 psig airflow, since WE were paying for new diaphragms ourselves. When nothing else worked (and we were just about out of beer), I suggested that Robin walk up and push on the fuel controller's solenid shaft with his thumb. It went rapidly to full power and quit. It SOUNDED like it quit because it went lean rather than rich. Anyone who flies radio control models will know the difference or buy a LOT of engines. After a restart, he pushed much softer and could hold it there for about 10 seconds before the radiant heat from the jet tube started to burn a bit too much. It singed me once or twice, too. So, we added a spring-loaded set of washers that clamped the solenoid shaft with a screw-knob. You push it down to where you want it and clamp it there and jump away from the heat.

We next turned off the 90 psig airflow and then opened the air blocking valve and loosened the screw-knob ... and the old German fuel controller kept it running! It took maybe another 3 - 4 runs to perfect the process and we could get consistent runs.

Then we added another solenoid controlled by a 10-turn potentiomenter that adjusted the second solenoid current. Now we could push down the first solenoid shaft from the remote box by turning a knob! That made things a bit cooler during runs.

Right when we got it figured out, the 2009 Chino airshow was coming up and they let us into the lineup, but were concerned it might blow up. So they made us run down the main runway on Saturday. Of course, you cannot blow up a pulsejet from within the jet tube under ANY cicumstances because there can be no explosion without containment (so no pressure buildup). One end of the jet tube is always open.

The only place you could get an explosion was the fuel pump area, and we were running an aircraft type fuel pump. So Steve said we could run down the taxiway on Sunday (if we survived Saturday). I'm not too sure most people appreciated the act, but we DID get a comment from several older gentlemen in the audience that the last time they had heard that sound was in London in 1944.

If nobody else did, WE had a good time with it. We were with the Planes of Fame, so we called ourselves the "Pains of Flame" Demo Team. Here is a pic of the license plate I made for the engine bed trailer. I got the V-1 picture from Romatic Technofreak of this forum.



The pic is from a video game and the girl losing her panties is the result of too many beers, or not enough ... I still haven't figured out which. We put that on the back of our polo shirts, too, and all wore them during the airshow runs. We still have the shirts ... but they're a bit faded today. Silkscreening isn't what it used to be ...
 
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Hi Greg;

Great stuff here!!! Don't know much about how the Mars was taken care of but I did work with a PBY owner and I could tell you that corrosion control was like plugging holes in a leaky dam with your fingers, it's a never ending process especially if the aircraft is landed on salt water. We would treat and if necessary repair anything that seemed to really get into the parent material. The PBY I worked on came from Spain and despite it's age was well taken care of. IIRC we spent more time plugging leaks in the hull, it seemed like the green fuel tank sealant worked the best.

Sand, zinc chromate, prime, seal or paint, repeat.
 
Hi Joe,

Somehow I figured you would have worked on flying boats.

The only sea-dwelling aviation constructs I have worked on were much the same ... as much or more work on corrosion than on the rest of the aircraft. I know a couple of guys up in Alaska who have floatplanes. They stay firmly in fresh water except in an emergency and STILL have to do very regular looks at the airframes and pontoons to keep up with it.

I'm glad most military fighters days are land planes. That way, when we restore them, most of the metal is still there.
 
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