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X-ray images of flowers by researcher and designer Mathew Schwartz form the identity of this year's Dezeen Awards. This year's Dezeen Awards features media categories for the first time, with awards for architecture photography, video and visualisations plus websites for studios and brands. Introducing new Dezeen Awards prizes for sustainable architecture, interiors and design! Our three categories celebrating projects that make positive environmental and social contributions are now open for entries.
Dezeen Awards is now accepting entries! Enter before 31 March to take advantage of discounted early entry fees. The third picture shows another area of dead air, this time the upper surface of the aileron. The boundary layer evidently thickens significantly, or separates entirely, aft of the gap.
The next picture illustrates a curious phenomenon: spanwise flow near the trailing edge. The flow direction is inboard on the upper surface and outboard on the lower, and is related, I assume, to spillage at the tip and to formation of the tip vortex. Finally, here is the flow around one of the flap track fairings. It's interesting that the flow does not hug the fairing, but seems to spread out away from it.
There must be a pool of low-energy air close to the intersection. I don't know whether more of a fillet would improve the situation; I doubt it. In this picture, as in the first one, the transition from laminar to turbulent flow is visible.
It seems remarkable that this year had no October. After making and breaking a number of appointments I finally got the propeller balanced per the recommendation of Art at Able Air back in June. I approached this operation skeptically, feeling that the idea that you ought to balance your prop every hours was like the advice of shampoo manufacturers that you apply the stuff liberally and twice. But I tend to make the miser's assumption that everyone is out to swindle me. The traveling technician who performed the operation was named Leo Chrisostomo.
Had I know this in advance I would have been even more suspicious, since the name, which means "golden-mouthed," suggests someone particularly persuasive and therefore potentially misleading. Leo connected a couple of what I thought looked like accelerometers, but he said were now called "velocimeters" I think , to the front and back of the crankcase and had me run the engine at 1, and 2, rpm.
An oscillograph made squiggly lines. Leo's expression suggested that he found the results a little startling. My engine, it seemed, was very far out of limits, registering 1.
If this had been PSA, relatively speaking, I would be a goner. I was puzzled that the engine could be so far out of whack and yet feel so smooth, but he said it was all in the Lord mounts. Thanks be to thee, O Lord, as St. John Chrysostom probably used to say.
He screwed a couple of weights onto the prop hub and we tried again; now the excess was merely half of what it had been. Another pair of weights and the engine was within limits, if just barely. We stopped there. I took the plane around the pattern and indeed it felt different -- silkier, as it were.
After all the thinking about the flap position buzzer back in September, I decided to try the simplest of all options, namely a buzzer and a microswitch, nothing more, with the thought that in the time it takes me to react to the buzzer the flap will have continued past the microswitch anyway, and so there may be no need for additional ingenuity to keep it from buzzing interminably. I dropped the plane at Able Air yesterday with trepidation, but Art called me a few hours later to report that the mag problem had simply been a plug "packed with carbon" on the 3 cylinder.
Evidently my carbon-detecting skills are poor, since I had inspected all the plugs and not recognized this condition. I wish I had been there to see what it looked like. He suggested that I lean the mixture while taxiing, something that I know is desirable but have lazily neglected to do.
A kindly correspondent pointed out that in original version of the circuit below the capacitor should have been in parallel with the Sonalert, not in series with it.
Russ Hardwick was innocent of this error. It was sheer stupidity on my part, like thinking that you fill a bottle from the bottom and empty it from the top. I have now corrected the sketch. Matters have been temporarily derailed by a rpm drop on my right mag. I inspected all the plugs, found nothing remarkable, and put everything back together. No improvement. The shop I am currently annoying with my business, Able Air, can't look at the plane til next Thursday.
Maybe that will encourage me to make some headway on the intercooler tanks. Last week Russ Hardwick and I discussed how to design a circuit to produce a tone lasting one second or so any time the flap passes, or stops at, the takeoff position. I felt that I understood at the time, but now I have forgotten again. I think there's a microswitch or a reed switch, a relay, a capacitor and a Sonalert, and you just connect them in all possible ways, one after another, until you get the desired effect.
Just kidding. Actually, I think this is the circuit. I just need to figure out the right size capacitor for the Sonalert. The behavior of the circuit relies on the capacitor filling up much faster than the relay actuates.
A simple audio tone to announce the arrival of the flap at the takeoff position would make it unnecessary to watch the flap going up or down.
I happened to see a professional test pilot's evaluation of a certain airplane whose flying qualities are generally admired. I began to think about how Melmoth 2 would fare under such unsparing scrutiny, and I concluded that there are many obvious faults which I had simply agreed with myself to overlook. One is the way the flap operates. To raise or lower the flaps, you move the flap handle to the up or down position until reaching the desired flap setting, then re-center the handle.
The gear works the same way. The handle operates a cable loop that goes to a valve. It also carries a two-lobed cam that triggers a single microswitch to operate the hydraulic pump. There are, for practical purposes, only two flap settings, takeoff and landing. For takeoff, the flap extends aft but deflects only a few degrees, producing a large area increase but only a small change in drag and pitching moment.
Because of the long distance traveled 15 inches at the wing root the flap takes about 12 seconds to reach the takeoff setting. It takes only two more seconds to get to the full 30 degree deflection. You can see this here and here. Because of the rapid increase in drag and pitching moment associated with flap deflection beyond the takeoff setting, the pilot's attention is diverted most critically, while setting the flap to the takeoff position at the start of a landing approach by the task of monitoring the flap travel.
Also, after takeoff, while retracting the flap, I tend to watch it while waiting to shut off the hydraulic pump, even though it does no harm for the pump to run for a few seconds against its own bypass valve, which emits a faint but useful scream of protest. I have an unfortunate tendency to anthropomorphize machines; for instance, I don't like to keep my computer waiting.
Landing gear operation involves similar deflections of pilot attention, but for shorter periods; the gear cycles up in five seconds or so, and down in two. Lying on my back on top of Mt. Wilson last night while watching the generally disappointing Perseid meteor shower imagine the even greater disappointment of the fellow who installed a inch telescope there, only to notice, too late, that Los Angeles was just below I mulled over how to mitigate this situation.
During the retraction cycle, I would like the hydraulic pump to automatically stop when the flap is fully retracted; during extension, I would like it to stop at the takeoff setting. But then what? The flap handle is already down. There could be a pushbutton next to the flap handle that would override the limit switch and let the flap run down to full deflection. There is a problem implementing this seemingly simple arrangement, however. The same microswitch on the flap handle energizes the pump during both up and down cycles, so whatever happens on the trip down will happen on the trip back up.
Do I want the flap to stop at the takeoff setting when I'm trying to retract it? Well, maybe yes. For a go-around, for instance, that would be desirable. But there is a bigger problem. At present there exists a clear, unvarying relationship between the position of the flap or gear handle and the state of the hydraulic pump. But once you add "logic" to the system, in the form of a second microswitch overriding the first, you introduce weird new possibilities.
For instance, suppose the flap handle is down, the flap is at the takeoff setting and that limit switch has turned the pump off. Now I lower the landing gear. The gear handle microswitch now energizes the pump; fluid goes to the gear and to the flap as well because the handle is down , the flap moves past the limit switch and runs down to full.
Or the inverse would occur if the flap handle were up. Either effect would be highly undesirable and potentially hazardous. There are certainly ways around such difficulties, but they involve increasing complications, make the system harder to understand, and create new modes of failure. Maybe a better approach would be to not let any professional test pilots evaluate the airplane. I have accomplished nothing at all lately. Most days have been sucked up by writing, kid transportation or hot-weather laziness.
When an empty day presents itself Nancy and I drive up to Ojai to help our son Nick with his house, into which his family intends to move in less than three weeks. Nick and I did fly down to Jacumba, on the Mexican border, on the 20th, to look at his '68 Malibu, which is being refreshed there like Aphrodite at Paphos. The trip down was a bit crawly, but on the way back we had a knot tailwind at 12, feet, it was very clear and smooth, and we crossed right over the top of the LAX Class B and had a long fast dive to Santa Paula, where Nick had left a car.
A long time ago I wrote about the pleasure of descending from 20, feet in Melmoth 1 and seeing knots on the DME while listening to a favorite piece of music, and I mused about whether the pleasure might have been further increased had I had a slice of sachertorte to eat at that moment.
I have since concluded that pleasures do not always add arithmetically, but sometimes tend to subtract from one another. Jacumba is an odd little place. There are hot springs there, and our friend said that it used to be a resort of Hollywood types, like, say, Two Bunch Palms in "The Player". The recently paved 2,foot runway is right next to the border fence, a not especially forbidding-looking palisade through which a sufficiently svelte person could probably slip without much difficulty.
It would be still easier, however, just to stoll over to the 1,foot gap about half a mile east of the runway, which would give the Clown in Chief a well-deserved conniption. Late in June I sent away an oil sample for spectroscopic analysis.
The last time I did this was in , shortly after Melmoth 2 began flying. It's interesting to compare the results from two analyses 15 years apart. With the sole exception of copper, which went from 4 ppm to 6, all of the wear metals are present in lower concentrations now than when the engine came out of 20 years of storage.
Aluminum went from 12 ppm to 2, Iron from 53 to 37, Nickel from 7 to 6 and chrome from 3 to 2. The engine now has 1, hours. At this rate it will soon cease to wear altogether, except for its copper parts. The oil analysis firm does not provide tolerances, except implicitly, through the use of decimal digits, which I have rounded for the sake of simplicity.
But it says that all values appear normal. That was a relief. In case anyone is interested in this sort of thing, the so-called "tanks" that conduct air into and out of the intercooler have to sustain an internal pressure equal to the maximum boost, as well as, on the inlet side, a temperature of around deg.
So part of the design process is to decide what "maximum boost" is going to be. If I wanted to be able to get 41 inches at FL, where the ambient pressure is about 15 in. Hg, max boost would be 26 in. Being more frugal than impatient, I never use even that much anyway. The area of the intercooler face is about 47 sq. The latest on the alternator coupler is that it is both a vibration damper and a shearable link.
So much for that. I put the alternator back into the plane on Saturday. I had a hard time with the transverse exhaust pipe, which passes behind the alternator and has to be removed to allow the alternator to come out. The pipe, which has the heater shroud wrapped around it, is straight, with a tapered flange at each end; the mating parts also have flanges, and these flanges are drawn tightly against gaskets by circular clamps with a V-shaped cross-section.
The pipe looks as though it ought to be able to be put in either way, but actually the flanges on the two ends are of different types, one thicker than the other, and the flanges on the mating parts are as well. It turns out that you have to mix, not match, to get the clamps to work; if you put the two thicker flanges together, the V-groove can't handle them.
I suppose I may have known that once, but if I did, I forgot it, and it took me about half an hour, and some bloodshed, to figure it out anew. Once I got everything back together, the alternator checked out fine on a runup. I then decided to do an oil change, and to get a spectroscopic oil analysis while I'm at it, something -- the analysis, not the oil change -- I haven't done for 15 years or so.
Things went fairly smoothly this time, since after last time's flood I wrote "Aft end" at one end of the trough that conveys the used oil into the bucket. My supposition about the function of the wildly expensive coupling between the alternator and its driving gear was apparently incorrect.
According to the technician at Aero Accessories from whom I picked up the overhauled alternator this morning, it's just a plastic connection designed to avoid dropping metal fragments into the engine in case the link fails. But I wonder whether he's right. In any case, he said that failure of the outer case of the alternator is something they see maybe once a year. He assumed it was due to vibration wearing the aluminum threads, so that the steel bolts and safety wire all remain intact, but the whole structure comes loose.
Lacking a belt to damp the torsional vibrations of the engine, the direct-drive alternator requires a flexible coupling between its shaft and the gear that engages the accessory drive. After some number of hours of use, this coupling wears out. It is no longer possible to secure it to the alternator shaft with the required torque, and it must be replaced. This was the case with mine. This experience has reminded me that I am not really in the airplane owner demographic, and my flying career will last only as long as not too many expensive parts of my plane break at once.
I took the plane to Able Air this morning. The problem with the alternator turned out to be the alternator. In the seven years since I installed t, it had shaken itself to pieces. This is a little hard to understand, because the engine is quite smooth and I feel that the vibration level in the plane as a whole is low, but, as the mechanic said, you can never tell about vibration. What was surprising, and instructive, about this was that I had inspected the alternator before taking the airplane to the mechanic, and noticed nothing; but my attention was directed to the wire connections, and since the alternator itself was ostensibly intact, with all its bolts and screws and safety wire in place, it never occurred to me to grab the end of it and shake it to see whether it was coming loose from the rest.
The mechanic asked when I had last had my prop balanced. Forty years ago, I said. He suggested that every hours would be a better interval. I took off for Paso Robles this morning to attend the annual Antique Aero barbecue, but turned back after 20 minutes with the ammeter indicating a continuous five-amp discharge and the voltage meter just 24 volts. I've seen flakey behavior in the charging system before, including on the previous flight, but always the system would pull itself together after a few minutes and do the expected thing, that is, initially indicate a charge as the battery recovers from starting the engine, then gradually drop to zero charge or close to it and maintain a steady 28 volts.
I tested my old epoxy a few days ago; it's still good. I don't have much graphite cloth, however; I have to decide whether to settle for glass or spend some money. I'm tempted to use glass just because it's so much more cooperative. Graphite is so stiff, it's a pain on small radii like these. Maybe I can use a little of each; that would seem high-tech. The intercooler inlet and outlet tank molds are ready for laminating. I need to find out whether my out-of-date high temperature epoxy will still harden, and whether I have enough carbon cloth for the parts I suppose I could use glass; it's a question of stiffness, not strength, and so carbon would be preferable.
More important, I need to figure out how to split the parts in order to be able to get them free of the molds. The molds represent the inner surface of the parts; in other words, the parts themselves will be laid up over these molds. When I am thinking about the airplane here at home, I often refer to photographs to refresh my memory of the arrangement of certain details, particularly ones inside the cowling.
This morning I began to reflect that the ambient pressure source for the injectors and mags -- both of which are pressurized by the turbocharger -- and possibly also for the manifold pressure gauge, is a tap in the duct leading into the throttle body, and that this tap is at a right angle to the flow direction. Since the flow speed in that duct is around mph, there might be some pressure drop, and so I may not be getting full pressure.
I consulted my photos and found, first of all, that I was wrong about the MP source; it comes from the crotch of the Y downstream of the throttle body. At least I think it does; actually, every one of my photos manages to hide that area, which resembles the pudendum of a putto, as modestly as those fortuitous bits of foliage and fabric in paintings of yore do the corresponding parts of Venus, Mars or Jesus. But it stands to reason that the MP pickoff would be downstream of the throttle; I was silly to think otherwise, however briefly.
At any rate, I shall go to the airport today and visit the scene in person. Fortunately, my manifold pressure gauge has two needles, one of which tracks ambient pressure and provides, for anyone who can subtract, a crude but reliable backup altimeter. I can temporarily hook that one up to the pressure tap that goes to the mags and injectors; the two needles will show the pressure drop, if any.
The story of the Lowrance GPS continues, and never fails to amuse and astonish. The last time I reported on its behavior, in December, I had replaced its internal battery and it was now remembering to send position data to the autopilot; but it had stopped offering airports, NDBs and such stuff as Go To options, and was confining itself to waypoints, of which, incidentally, none were programmed.
In addition, its map would display road, airport, position and track data, but not airspace boundaries. I was pretty well resigned to this state of affairs when one day it suddenly remembered its airports and NDBs.
Then it would not search properly; it would go up to about the middle of the alphabet and then jump back to the beginning. After a couple of restarts, however, it abandoned that annoying behavior and acknowledged the entire alphabet.
A couple of flights later, airspace boundaries suddenly appeared. It was like a stroke victim slowly relearning how to speak and walk. I do not know enough about electronics to understand how a device like this, which must have about the neurological complexity of C.
The ghostly lineaments in the previous entry are taking as yet unfinished form as wooden molds. The intercooler tanks will be laid up, using carbon fiber, over these molds. The one on the left is the inlet. A kindly reader expressed concern about my long silence.
Actually, I am well and so is the airplane. The nation, maybe not so much. I have done very little work on the plane lately, for several reasons.
Plus, although I feel I am getting closer to the correct solution, I am still uncertain about some details of the intercooler plumbing. I am pretty sure, at least, that I have the position right. Here is the palimpsest upon which my runes are inscribed:. I do not expect this to be comprehensible; I am including it just to show that I do occasionally pick up a pencil or, more often, an eraser, and inflict something upon a piece of paper. The process has been somewhat impeded by my stupid choice of some redwood that happened to be lying around here as the material from which to make molds for the two high-pressure "tanks" that bring air into the intercooler and conduct it thence to the throttle body.
Redwood is a material of constantly varying density, and singularly ill suited to mold-making. However, once I have made a mistake I am determined to persist in it. I am pretty satisfied with the inlet and outlet paths for the induction air, although the very tight degree turn to the throttle worries me a bit, just in terms of its effect on flow distribution in the log manifolds.
The cooling air is a different story, but it, at least, I can defer thinking about until a later time. I tried a different position for the intercooler, and I think it's better. The inlet path for cooling air is less obstructed, and the paths for the charge air both into the cooler and from the cooler to the throttle body identifiable as an orange sleeve in the photo are better aligned. But I am still waffling about the whole idea, in part because of the weight of the intercooler itself -- around six pounds.
I think it's bigger than it needs to be. Someone cautioned me against sawing off one end of it, but I don't know what difference it would make if I did so and just bonded a new end plate to it with a mess of JB Weld.
At any rate, the non-airplane aspects of my life have been more than usually complicated lately, and I've spent less time than usual on the plane. So between lack of time and uncertain motivation, the intercooler is making no headway at all. Moving at a more than usually glacial pace, I mocked up the intercooler placement, using wood wedges in lieu of the eventual "tanks".
I don't like the arrangement, now that I've seen it, and am going to try a different one, with the large face of the core horizontal rather than vertical. After writing an Aftermath column in which the cause of the crash was the pilot's faulty handling of an aborted landing, I became curious about whether Melmoth 2 could climb with full flap and airbrake -- one of many things that I have never tested.
The airplane was extremely light, however. The only problem was heating; the CHTs rose rapidly because of the low airspeed. The proper technique for a go-around would be to maintain level flight initially while cleaning up and accelerating. The pitch changes with airbrake and flap retraction are quite marked, but easily managed if you're prepared for them.
I collected some temperature readings in the duct leading into the oil cooler, with and without the deflector. The temperatures were, on average, 20 degrees F above ambient with the deflector and 30 above without.
This suggests that maybe I ought to look into making up some sort of duct that runs directly from the peripheral intake to the oil cooler; at present the oil cooler duct takes in a mixture of deflected cold air from the peripheral duct and warm air from the plenum.
Incidentally, these data were collected while cruising at 4, feet at ktas on 6. Today the unpredictable 1 Lowrance worked, to some extent. Now that I have replaced its internal battery, it remembers that it is supposed to be producing NMEA output for the autopilot coupler.
On the other hand, it seems to have forgotten its airport and navaid data, and now offers only user waypoints in response to the "Goto" command. I suppose it would not be that much trouble to program the waypoints I use most often.
But would it remember them? On the theory that air directed along the bottom inner surface of the cowling by the splitters I installed in the inlet might be sticking to the surface for Coanda-like reasons and not getting into the oil cooler inlet duct, I installed an aluminum deflector on the floor of the plenum in such a way that it would steer this putative river of cold air into the duct.
The first time I tested it in flight I got the impression that it had had a remarkable effect; but as time went on the effect appeared to vanish. The only way I will know for certain is by measuring the temperature in the duct with and without the deflector in place.
My seemingly successful installation of a new battery in the 1 Lowrance has resulted in a unit that remembers its settings, but refuses to lock onto a satellite, even though it passes its self-tests okay.
Meanwhile, the 2 unit, which is currently installed in the airplane, has developed a new problem: it remains on for only a few seconds after startup, and then turns off. I suppose it is foolish of me -- perhaps I am a deranged US dotard -- to suppose that electronic devices almost 20 years old can be expected to function normally.
Here's another plot of the same data, this time temperature rise versus net boost pressure above or below ambient. Different altitudes produce scatter, but on the whole the points line up fairly well. Yesterday I collected some baseline data that will allow me, at some future time, to assess the effectiveness of the putative intercooler. I recorded induction air temperature at 20, 25 and 30 in. Hg at 4,, 8,, 12, and 14, feet. I had intended to finish the series at 16, feet, but it became apparent that the temperatures were getting quite high and I did not want to venture past deg.
Here are the data I collected:. The left-hand chart is simply the right-hand chart minus the OAT. The astute viewer will wonder why the temperature rise is so large even at low manifold pressure and low altitude, where no compression at all should be taking place.
The reason is the peculiar design of the Piper "fixed wastegate" system that I have modified to incorporate a manually adjustable wastegate. This is an inefficient arrangement, obviously, but by using low rpm these tests were run at 2, rpm, but I often go lower I can open the throttle fully at 8, feet or so. I seldom cruise lower than that -- more usually above 10, feet.
It's evident, anyway, that there's a good deal of heat to be gotten rid of. One question on my mind was whether I needed to provide a separate cold air intake for the intercooler, rather than use the air already in the "cold" plenum. The temperature near the firewall is about 45 deg F above ambient -- this due to heating by the exhaust pipes and the turbocharger. But it might be worth a try, nevertheless. Following his advice, I crammed a new battery in with padding to press the contacts against it, and voila, it remembers!
But -- can it be TSO'd? My design process has always involved obsessively thinking about the object to be designed. I remember, during the construction of Melmoth 1, intensely visualizing the retraction linkage for the main landing gear while meditating at the Cimarron Zen Center of Rinzai-ji. How, I pondered, is the gear koan to work? I am now at the same stage with the intercooler. My recollection of the details of the engine compartment is not so complete or exact that I can mentally map every attachment and duct path, but I have dozens of photographs of it to help me.
A number of criteria must be met. The intercooler must be able to be built piecemeal, without having to ground the airplane for long at any stage. It must be easy to remove, with as few attachment points as possible, and have short, direct flow paths. It must require moving or damaging as few existing items as possible. My mental scheme is like a rapidly oscillating object that at first appears blurred, but, as it slows, acquires sharper outlines and at last halts in place.
The most suitable location for the heat exchanger seems to be on top of the present induction air box, rotated so that the aft inboard corner touches the firewall while the aft outboard edge is about an inch and a half from it.
The firewall thus forms the roof of the wedge-shaped "tank" that feeds cooling air into the core. On the opposite side, a similar tank for that is the name of the end housings through which air enters and leaves , also deepest at its outboard end, collects the heated air into a 3-inch SCAT hose that discharges forward into the upper plenum. A third tank, on the bottom surface of the core between it and the induction air box, is connected to the existing riser coming from the turbocharger; on top of the core, a fourth tank feeds the cooled air to the throttle.
In this arrangement, the intercooler is attached to the airframe, not the engine, and three flexible segments are required to join it to the engine. I am reluctant to attach such a large, relatively massive object to the engine. I have not yet found out how much cooling air the intercooler requires. A turbonormalized Bonanza has a ram air intake about 3 or 3. I had thought about constructing a pitot-style inlet with a boundary layer channel, but I decided it would be rather complicated and possibly draggy, so my present thought is to replace the existing NACA scoop in the cowling side panel with one about three times larger.
This would supply both induction and charge cooling air. I'm not sure what the politics of splitting the inner channel of a NACA scoop are, but I'll find out. The most difficult part of the whole project, I think, will be making the induction-air tanks, which have to withstand both heat and pressure. In the meantime I attempted to break into one of my Lowrance GPSs, having learned from the company that they no longer support such ancient devices as mine.
There are no external screws on the case, which seemed to be glued shut. I cracked the joint with a chisel and pulled the halves apart sufficiently to see the battery that maintains the device's memory. Unfortunately, it is soldered to the circuit board, and so there is no practical way to replace it.
I talked with someone who knows something about intercoolers. The guidance I came away with was that 1 I should not try sawing off the end of an intercooler core; 2 small differences in size are not critical, since the original choice of a size was probably based on false assumptions in the first place; and 3 the cooling air flow requirement is about what fits in a 3-inch SCAT hose.
Ah, the cool, fresh air of simplification! The puzzle of the failure of the autopilot to couple to the GPS is solved. The problem seems to have been related to the Lowrance's having lost the memory that restored its previous state at each startup. One of the settings that were being lost on each shutdown was "NMEA On" -- that is, the command to send course deviation information to the autopilot.
If I reset that selection on startup, the system works as expected. The failed memory is presumably sustained by an internal battery, and that battery has evidently lost its ability to hold a charge. I assume there is a way to replace it, but so far I have not even figured out how to split the case. I will. My vague plan to install an intercooler has advanced to the point that I have more or less decided where it will go. The next step is to find out whether I can make one of the heat exchangers that I have smaller by sawing off one end of it.
I have three cores, one of which was originally intended for a hp engine, one for a hp, and the third for a hp McCulloch two-stroke. Obviously, the last is too small, so forget about it.
The others are too big, and for reasons of weight, space and internal resistance it is probably not desirable to have excess intercooling capacity. At any rate, I need to figure out how big an intercooler is appropriate and what volume of cooling air it will require. The borescope did not find anything obviously wrong with the 4 cylinder. It did make a nice portrait of the top ring gap reflected in the polished cylinder wall:.
I ran the engine for a few minutes and then checked the compression of the 4 cylinder again. I thought that 40 didn't seem likely. At the end of the eclipse trip, which involved about eight hours of flying, there was a fine mist of oil on the right side of the windscreen, enough that I could not see clearly through it. The oil consumption had not been out of the ordinary -- about one quart in 10 hours. It was evident from that, and from the fact that the mist had not coalesced into large droplets or streaks, that the amount involved was small, but evidently from some new source, since I had not seen this problem before.
Lengths of aluminum tubing were simpy slipped into the elbow without any kind of positive seal, because I had thought there would be very little pressure in that line. I now contemplated cutting O-ring grooves in the elbow, but settled for gluing the tubes into it with red silicone. I then did a compression check for the first time since January, -- "If it ain't broke I suspect that there may be some little speck of carbon or something under a valve, and that if I fly and then check the cylinder again I will find it in line with the others.
I had the Porcine Smart Coupler benched checked by its maker, and he reported that it is okay, which, he said, was too bad in a way, because troubleshooting the rest of the system will be more difficult. I may have to give up the Lowrance GPS, whose behavior has grown increasingly flaky, and replace it with something newer.
Unfortunately, the iPad , which provides a beautiful navigational display, does not provide the digital output required to link it to the autopilot. In the meantime I have been toying with the idea of installing an intercooler.
I have toyed with this idea before, but never gotten past the toying stage. I have several intercoolers lying around, none of which will be suitable for my hp engine without modification.
I don't think I have any practical need for an intercooler -- I seldom go above 14, feet -- but I would do it, if I do it, just to round out the tubosystem.
A highly compressed video of the eclipse trip is here. The curious pattern of light on the instrument panel -- and everything else in the cabin -- was, I think, a schlieren image of density variations in the plexiglas of the canopy. The universe was kind enough to schedule a solar eclipse on my birthday, so on the 20th my son Nick and I flew up to Winnemucca, Nevada, where we spent the night before continuing to above Weiser, Idaho.
There we observed, or perhaps a better word is experienced, the event from a perch at 14, feet. Enough has been written about this eclipse that I will not add my two cents, except, first, to explain that the tawny line along the horizon in the photo above, taken at a.
MDT from the middle of the umbra, was due to smoke from fires in Oregon, and, second, to note a curious optical phenomenon whose cause I do not know. I suppose it must have something to do with the plexiglas canopy, but for some reason the only time I have ever seen it was just before and after totality in this eclipse. All surfaces appeared pebbly or rumpled. The paper on my kneepad looked as if it had been soaked in water and then dried, and the instrument panel resembled the surface of a hilly, eroded landscape.
The house work goes on, but on Saturday I woke up early and slipped away to the airport. I was obsessed with wondering whether there was a way to get the leaky nosewheel hydraulic cylinder out of the airplane wihtout having to dismantle everything surrounding it, which requires jacking the airplane and is a big pain in the neck.
The freeway was conveniently empty, the airport dim and silent. I quickly found that yes indeed, there was a way; and in ten minutes the cylinder was out. I opened it up and inspected the O rings; everything appeared okay. I left it on the workbench for further inspection. As I was leaving the airport I heard a plane heading down the runway, and I glimpsed it as it began to climb out. It was an airplane I always see parked, but had never before seen move: a Scottish Aviation Bulldog, quite a rarity in the US.
I flew today for the first time since June I have been completely absorbed in house repairs, but they are finally coming to an end. I went up to Tehachapi, a bit less that half an hour away, where Mike Melvill has his hangar. I circled overhead but did not see his car; he is probably not yet back from Oshkosh and from visiting friends in Indiana, where he and Sally lived before they came to Mojave to join the then nascent Rutan Aircraft Factory.
The Smart Coupler is still not working in spite of my having repaired a broken wire. On approach to Whiteman I found that the flaps would not work -- obviously low hydraulic fluid again, and on inspecting the usual leak sites I found that the nose gear hydraulic cylinder, which I thought I had repaired early in May, is again leaking copiously.
I hope I can figure out a way to take it out without having to dismantle the entire nose gear retraction linkage again. This time the leak appears to be between the outer tube and the piston-end cap; last time I thought it was around the piston itself. The one repaired thing that worked properly was the 2 radio. It didn't take long to discover that the cause of the failure of the GPS to talk to the autopilot coupler was nothing more complicated than a broken wire.
I fixed that. I then pulled the 2 comm radio, which I took home. Going by feel, I put, or at least I hope I put, the switch into the "Select" position, where it will henceforth remain. Another plastic knob, the tiny one that controls volume and squelch on the 1 comm, turned out to be cracked.
I'll find a replacement for it. I flew to Oakland yesterday, and there encountered an instance of the often forgotten fact that every feature entails a vulnerability. My comm radios are Collins Micro-Line dating back to or so.
They're great radios and I have no complaint about them at all. One of their features, which was novel at the time I think but has since become standard, is a "Store-Select-Recall" switch that allows you to store a frequency for future use or to "remember" the current Center frequency before switching to the next one en route. In my radios, this is a rotary switch, and when I turned it something broke, leaving the radio in "Recall" mode and therefore incapable of selecting a frequency.
One interesting data point was that after climbing to 10, feet and cruising for a while, I decided to re-adjust the mixture.
As usual I was running lean of peak, and I found that I had to enrich by deg. So I now know that the engine will run smoothly at LOP. We returned on the 13th from Cape Cod, where we ended a trip that began in Mid-may with Nancy's 50th college reunion in South Hadley, Massachusetts.
This was a three-day affair during which I met, among other people, a woman whose father, Charles d'Olive, scored five victories in Spads in World War I. Too late, sadly, to relate the encounter to my friend Javier Arango, who would have been delighted by it. I had been having two problems with the unit. One was that it often had to be restarted several times before it would show a complete map; initially it would leave out stuff like the boundaries of Class B or C airspace. The other was that it had stopped talking to the gadget that converts GPS course deviation information into autopilot commands.
The replacement unit, once it had figured out that we were not in Tulsa, resolved the first problem but not the second. The second, however, is the more important, since the iPad provides a Technicolor map six times larger than the Lowrance's black and white one, but no autopilot output at least that I know of.
Before leaving for the East on April 14, I overhauled my leaking left brake master cylinder. On returning, and after due delay for getting my affairs in order, I took the nosegear retraction apparatus out in order to fix a leaking hydraulic cylinder. While I was at it, I changed the oil.
A couple of months ago I had made a permanent version of the temporary gutter that I hit upon in July, as a way to drain the oil without making a huge mess. Unfortunately, there are two ways to install it, and in obedience to Murphy's Law I unreflectingly picked the wrong one, with the result that two quarts of oil went into the bucket and six went onto the floor.
Luckily I had a tub full of absorbent stuff, basically kitty litter I think, left over from the big fuel spill of January, , as well as a pile of old clothes, sheets and towels that I had husbanded against just such an eventuality, and I was able to stanch the Stygian flood before it had advanced more than a few feet in several directions.
The nose gear hydraulic cylinder turned out to have a prolapsed O-ring. I got everything put back together and cycled the gear today; no time to fly, however. The iPad installation turned out quite well. On the first outing, it was free of reflections and perfectly visible as long as I did not look at it through my polarizing sunglasses, which make it appear completely dark. It's simply hanging from a hook and supported by one short leg, and can be removed as easily as a coat hanger from a rack.
I was taking a couple of visitors up for a short flight at the end of which the flaps would not go down. It turned out that the hydraulic fluid was exhausted, having leaked out of the nose gear auxiliary cylinder that I noticed dripping the other day. Fixing that will probably be a couple of days' work -- it will involve removing and replacing the whole nose gear retraction apparatus -- and I won't do it until we return from the East toward the end of April.
Today, however, I did overhaul a leaking brake cylinder, apparently successfully. At a certain point there was a terrific racket outside the hangar; someone was running up a Stearman that appears, for the moment at least, to be my new neighbor.
In , Gary Maker was a private pilot, an airplane enthusiast and a Flying reader. He lived in the San Fernando Valley, and one day was at Whiteman Airport -- "back when a person could just drive back there and watch the planes" -- where he saw the then much-publicized Melmoth 1 and snapped a picture of it.
A few weeks ago he sent me this:. At that point the T tail and rear window mods had been done and the airplane was still unpainted. To judge from the clouds and the fact that the ground looks wet, this might have been taken in the late spring, but it appears to be of the same general vintage as another photo that was sent to me by Gino Barabani, and that has been in the "Melmoth 1, mostly pictures" section of this website for some time:.
Recently Barabani wrote to me, "The date of this photo was , it was a Tuesday. I read every article in Flying about your aircraft. This high school kid had to find out what kind of person could design and build their own aircraft, so I talked my flight instructor into letting me go to Whiteman field for my solo cross country.
How sad that you where taxiing out just as I had arrived. The picture was taken with an old Polaroid camera; after the black and white picture was developed I had to run a clear liquid stick over the photo, so I never saw where you went. I finally completed the iPad mount that I started thinking about in January. It looks good, but it remains to be seen how visible it will be; the transparent canopy is a powerful creator of reflections. After landing the other day I noticed hydraulic fluid leaking -- what else is new?
I wonder whether that can be related in any way to the adjustment I made to get the nosewheel doors to close flush. It's hard to see how the two could be connected, since the leak is occurring when the gear is down, not up.
At any rate, the change made the gas spring collide with the retracting arm, and so I have to revise the gas spring mount, which will require removing a bunch of stuff including the hydraulic actuator. I'll overhaul it then. Unfortunately, it turns out that the brake caliper is already up against the inside of the door, so that is not an option. I suspect that the best solution would be a narrower tire. My original tires allowed the doors to close flush; I probably discarded them, but may have some carcasses lying around somewhere.
Of course, there may be tires other than aviation ones that would fit these wheels. No doubt there is an All The World's Tires listing somewhere online. This has been a lesson, albeit one I am unlikely to have an occasion to employ: Leave some extra space around replaceable items, because the replacements may not be identical to the originals. I flew to Santa Paula on Wednesday in hope of seeing a flight of the clipped-wing Harmon Rocket powered by a hp turbocharged rotary engine that is supposed to make an assault, when conditions are right, on the time to climb record for propeller aircraft.
The airplane was ready, but the pilot. He wants 20 knots of west wind down the runway, and the day promised only In fact, while I was there it was 10 out of the east. Paul Lamar, who is a huge advocate of rotary engines for airplanes and supervised the installation of this one, was just about tearing his hair out, since he has complete confidence in the engine, thinks the pilot's hesitancy is unwarranted, is certain that the airplane will easily better the current record, and can't wait for it to do so.
I did take advantage of the trip to buy some fuel, which is a dollar a gallon cheaper there than at Whiteman, and to wander about a mile up for half an hour or so in perfectly smooth and perfectly clear air, admiring the scenery which, at the moment, is still a pleasing green after a period of unexpectedly heavy and persistent rainfall.
After returning I peered into the wheel wells to see whether the idea of cutting holes in the floor to give the tires more clearance is practicable. It is not; the aft portion of the tire retracts against the upper cap of the rear spar. I taped one of the wireless video cameras to the belly in order to see whether the nosewheel doors were closing properly. They weren't:. The odd-looking spike in the middle is a propeller blade. The object to the left is the exhaust pipe, and the one to the right is a fairing enclosing the engine breather and cloaca.
The doors looked horrible, so today I jacked up the airplane and learned that the nose strut was not retracting fully and the tire was keeping the doors from closing. Fortunately, by shortening a certain link by a sixteenth of an inch I was able to get the wheel to retract fully and the doors to close perfectly flush. I noted, however, that the main gear doors were not closing fully either; they stick out a quarter-inch or more.
That is a more difficult problem, because the tires are already touching the roof of the well and the doors are as close to the struts as they can be. The wheels retract under the seats, and there are already wells in the underside of the floor there to provide them with the greatest possible space.
I believe that the back edges of the seats clear the floor by only a quarter-inch or so, so it may not be possible to raise the floor in the vicinity of the tires. Perhaps, however, I could cut two holes in the floor and seal them with rubber sheet. A few days ago I replaced the paper filter element in the hydraulic system filter. I had expected this to be a troublesome job, because some time back in the s an idiot using my body had installed the filter behind the instrument panel rather than in front of the firewall alongside the reservoir, where it obviously belonged.
As it turned out, getting at the filter was not so difficult as I feared, and I managed to complete the job without spilling a drop of either hydraulic fluid or blood. The filter element was quite black. Here it is, like a patient etherized upon a table:. This is the sort of thing the NTSB has a field day with when it's found in a wreckage. The actual height of the strip is about 1.
A closer look at about 20x magnification, its drama enhanced by Photoshop's "Auto levels" function:. To look at this you would suppose the hydraulic system would long since have failed, but it seems to work fine apart from occasional rebellions of the flap sequencer, which I pitilessly suppress. Where did all that finely-divided metal come from?
There are 10 hydraulic cylinders of various sorts in the airplane, and a corresponding population of aluminum lines and flare fittings. I suppose the shiny debris represents the sum total of the fine metal dust that clings unnoticed to the insides of lines and cylinders fabricated and assembled under non-clean-room to put it mildly conditions. Or maybe the pump is disintegrating. Apart from the eye-catching metal, the paper originally a pale tan color appears thoroughly clogged with black silt, which I take to be either extremely fine aluminum oxide dust or the wear products of Buna-N O-rings.
Whatever the case may be, it appears that an inspection interval of less than 14 years -- well, Assuming that there must be some physical problem in the 2 that is, left side, inboard flap actuator, I removed first the actuator itself, then the master cylinder that drives it, and dismantled and inspected each of them.
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Four Letter Jigsaw Puzzle 01 Workmate Wooden Workbench |
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