argoldman

As we can see, many times air doesn't go where logic says. A great case in point is the Mooney M-20C and similar. This plane had its oil cooler mounted in the front of the cowl, its face into the prop blast and the air flowing into the low pressure part of the undercowl area. It would seem that the air would flow from the high pressure area just behind the prop, through the cooler and thence to the low pressure area and then out. The cooler worked well and was used, in this position until LoPresti redesigned the cowel to make the VW of the skies into the speedster that they now claim it to be. What flow tests showed was that instead of the air flowing through the cooler from the front of the cowl exhausting out the back, it was actually going through the cooler from the cowl backward into the prop blast:irked: --- Go figure.

Roger, I may be speaking totally out of my hat (or other orifi) , but that never stopped me. It seems like there are two issues here. 1 the cotter pin stripping some threads which allowed the nut to turn freely but not come off. Was it the nut that was stripped or the axle? I assume that you are talking about the large nut that holds the wheel/bearing assembly to the axle. This may be a critical safety concern. The purpose of this nut is twofold. a. to hold the wheel on the axle and prevent it from going one way while the aircraft goes the other. b. to put a preload on the bearings (if they are tapered) so that they function properly, not self-destruct and allow the wheel to track in the direction preferred without wobble. The nut is tightened to a specific tension (usually by determining the drag on the wheel. This may be a critical situation.. Find out why this happened, the damage and replace/repair the damaged parts lest you impress all those on the ramp with low level aerobatics. The second issue, that of changing the tire without having to split the rims, is one that I have not heard of (in my relative lack of tire changing experience.) It sounds like you were able to remove the tire like an automotive tire. One thing that I would be concerned with is damage done to the rim (they are either aluminum or Magnesium and are quite soft.) Most of the aircraft tires that I have removed are real bitc# to break the bead from the rim (I sometimes use blocks of wood and the weight of my hanger door) Since I have never changed tires without separating the wheel, I may be way off base here. Is the tire the right size for the wheel or is there a mismatch? Did you damage the new tire by stretching the bead? Did you just replace the tube or the tire and tube? If just the tube, why? The size of the tube and tire depend really on the size of the wheel on which it will ride. Don't depend on getting the numbers off of the old tire as you may have the wrong tire for the wheel.

Steve, I suggest that you don't use tape for the same reason that you don't use it in fuel systems (little bits can clog) use the goo (teflon pipe stuff) My mistake was your calling them flairings. They are actually called fairings. Gotta run

Let's see if I follow you. You are trying to plumb your brake calipers. What kind of tubing are you using? The fittings that you show, in the picture, are compression fittings. You don't need any flairing at all. When you jamb the nut down, the little brass barrel shaped thing that goes on right after the nut, compressis, seals the tubing and the joint. If you are using metal tubing nothing further is usually needed. If you are using Nyloseal, no further is needed. If you are using Nyloflow, ( :mad: ) you need a brass ferrule which prevents the tubing from collapsing. Now if you are talking about FAIRING, that is a totally different matter. There are a couple of choices each of which must allow the gear to bend on landing so that the fairings are not cracked. Since I have not done this on this aircraft, I will leave that discussion to others.

next time !

Nicely done. Even with the extra plies on the outside, it seems like the tube sticks out the same amount that mine did. It is possible that the aerocanard plans changed the dimensions of the jig so that the OD came out the same.

If you want to come a little farther north, on Saturday, see my project and have lunch with the airport geezers, come to KENW (kenosha Wi). We eat around 12:00 Send me an email at argoldman@aol if you are interested

Steve, I just reread my plans for the tabs. (in less of a sleep deprived state) The aerocanard uses 16 plies of Triaxial cloth for each side of the tabs, 16 on the outside and 16 on the inside. I guess I can breathe easily now:cool2: What appears to be only a few layers of glass in my picture of the inside glass is an illusion as the way I laid these up is with a number of smaller wetted out lay up packets. (looking at that picture initially gave me a start also-- which all goes to prove-- don't look back at the work that you have done and forgotten why you did it that way:o My understanding is that knitted glass such as triaxial is approx 20% stronger than woven glass of the same weight (due to the fact that all of the fibers are essentially unidirectional (orientated as the equivalent of one 90 degree bidirectional with a single unidirectional layer at 45 degrees to the 90 degree angle formed by the two unis perpendicular to each other. ))Breathe.. this approximates a BID with a uni at 45 degrees. These fibers are laid on top of each other and stitched together rather than woven as the standard cloth that we use. BID and standard UNI are woven. The weaving process demands that each fiber is not straight but must joggle around, either above or below intersecting fibers ( or every other intersecting fiber as in crowfoot weave )(even with Uni), thus decreasing their strength. (that's why in the spar we remove the crosswise fibers on that heavy material. The triaxial cloth, I believe is somewhat heavier, per ply, than standard BID or UNI and thus has more strength. If we calculate, at 20% greater, multiplying 32 (total layers per tab) by 120%, we arrive at about 38.4 plys, roughly equivalent to the 40 specified in the Cozy IV (not even taking into account the heavier fabric per ply

Yes, Steve, There are only two big layups. All of these layups are continuous rather than being 1 continuous thin set of uni layups (on on the top and one on the bottom then to be reinforced by those extra bid partial layups. It is possible, that with the difference in the plans between the cozy and the aerocanard and the cozy necessity for the other plys that those additional plys make up the difference and give a flush surface at the MK-tube. What have others noticed in terms of the overhang? The difference may be between the Cozy IV and Aerocanard plans. In the Aerocanard we use 2 large multi-ply lay ups of Triaxial cloth (BID and UNI combined) (thus only the two colors) and no auxiliary layups as does the Cozy. The outside width of the tabs, and thus the amount that the tube projects, is determined by a Jig (Probably in both plans as they are almost copies of each other) The below pix show the way these are done. thanks for your vigilance. Just for grins, however, I will recheck my instructions.

as promised, I have attached some pictures of how I handled the landing gear tube situation Pix are slightly out of order. The first (left) is the gear with finished washers and bid cover, before trimming. The second shows the extra length of the tube. the third shows how I indexed the washers in a bed of flox so as to keep them perpendicular to the bore of the tube. The last shows the washer floxed on, before some fill flox and the bid cover (sorry for the blurriness in this picture)

ya ya ya:cool2:

Wayne, Good on ya! Thanks for chiming in Shortly after I made what I suggested in prior posts, I read of several incidences where there was this exact kind of slippage. The "fix" that you made is similar in concept to the washers concept that I used. Why not build that into the gear in the first place???? the cozy IV gear still relies on the tube/glass interface for for-aft strength (resistance), beefy or not. Steady gears to you

Beautiful pictures, and nice work Wayne, I guess that "I took the blows and did it My way" I can't understand why one would want to prevent the forward and rearward movement of the entire main gear depending only on the relatively weak joint created by the bond of the MK?? tube (sanded steel with divots (or the cozy Girrrls modification), embedded in flox) to the gear and tabs. Please convince me why one would want to do that (other than perhaps that that is the way that the plans were written, which of course have never been revised:rolleyes: ). My readings in the various web pages has supported my contention that this weak bond does, in some, indeed, fracture yielding basically a flox bushing in which the mk??s can move forward and rearward with respect to the gear and tabs (actually they stay in the same position relative to the gear bulkheads and the fracture allows the gear leg to move forward and aft with respect to the bulkheads.) The MK?? tube does not go through the bulkheads but buts against an aluminum plate the inside (between) the front and rear bulkheads and is captured there by tightening the main bolts. forward and aft forces on the gear thus are transferred to the bulkheads through the fragile interface of this cylindrical,sanded and divoted piece of steel embedded in flox. (but I repeat repeat myself myself) It seems that these connections through the tabs are not subjected to much rotation or there would be significant wear on the bearing surfaces as well as the bolts. Is anybody seeing wear here?-- does anybody look at that in their conditionals?? When these tube-glass bonds break, if they do, and have, one might not notice it unless in its slight movement, one notices different tracking, vibration, different tire wear or creaking noises emanating from the hindquarters. If one doesn't lift the gear off of the ground by the fuselage or engine (mount) one will never be able to detect if this fracture has indeed happened. Just out of curiosity, how many flying bird owners lift the plane off of the ground by the fuselage and give the gear a strong pull or hit to detect movement? I will try to locate my pictures tonight and try to post them. (I'm jealous of your pictures:p ) In that location, I, personally want a broad bearing situation, not the potential massive stress transmitted through a weak joint. One caveat, it has been a long time since I did this, and I may have forgotten some issues, but I don't think so. Land safely with a strong gear:cool:

The gear tab layups are massive layups and their ultimate thickness is dependent on the glass to resin ratio. That ratio is, to a certain extent dependent on the lay-uppers skill and experience, however more important to the ratio, in this application, is how the tabs are pressed (by wood blocks covered with duct tape as a separator. These blocks are put in place to shape the tabs and are clamped together. The tighter the clamp the more goo that will ooze and get on the floor reducing the amount of epoxy in and thickness of the layup. I found my tabs to be a little narrow also. However, I did not want the lateral forces of landing to be transferred to the gear bulkheads through the ends of the tubular thingies through which the massive gear bolts go, (MKMGA for you purists) which would have been the case if I had just put some washers on each side, with the ID the size of the bolt, to fill the space. (I believe that there have been cases of these parts being broken from their epoxy bonds and shifting, because of this). What I did was to bond washers, the IDs of which were the size of the MKMGA so that they butted against the tab, not the tube so as to transmit the lateral loads through the tabs, not the tube. It worked out well. I believe that I put one or more layers of BID over the washers, continuing to the tabs for further retention (cutting the center out, of course) to fill the gap that remained and to retain the washers. The asembly, from the rear bulkhead to the bid overlay to the washer to the tab, through the tab assembly to the other tab through the washer through the other BID layer(s) to the front gear bulkhead (or the reverse, if you will), barring any looseness is essentially one piece. The bolts and tubes which go through the tabs serve to hold the gear in place and to transfer the torquing load of landing (or standing) to the the bulkheads through the tabs. (The bolts, of course put the whole mess in a compressive mode bulkhead to bulkhead which prevents movement of the tabs with respect to the bulkheads, thus transferring the stress directly.) I do have some photos of that somewhere, if there is interest, I will try to find them and attach the (If I can figure out how to do it) By the way, this is an armchair engineer's evaluation-I am not trained as a real engineer but I play one on the web....If anybody with the proper credentials want's to chime in, I would welcome it. ( I will try to suppress my feelings of hurt) Disclaimer.. . The above is a description of what I did and my reasons for doing it. It does not, in any way represent anything other than that and is not a suggestion that you should do the same.

This probably goes without saying---- Each glass weave has specific strength characteristics and were chosen by the designer((s) to achieve specific goals. Do not interchange them, or substitute them without proper knowledge in things glass fiber. Rich

Got it, I was missing the vacuum inside of the pressure. Makes perfect sense now. Thanks for the clarification:)

Colin, I am a little confused about the autoclave process. Certainly the pressure increases the strength of the polymer. In using a simlar technique with methyl methacrilate we cure items under water pressure. This stops volatilization (outgassing) of the material as it polymerizes and gives a more dense and stronger product. Is this the same as with the epoxy? If you have a mold and lay prepreg on it and then subject the entire thing to pressure, the air pressure will be the same at the surface of the glass as it will be at the surface of the mold and thus there will be no pressure benefit of adapting the glass better to the mold. If the mold is porous and the pressure escapes through the mold, you will have a pressure differential possibly forcing the glass into the mold--- but you will probably only succeed in bleeding the epoxy from the glass through the mold. The vacuum bagging technique (no heat) actually relies on the plastic film pressing the glass into the mold since the mold is non-porous, the plastic is non-porous and when vacuum is applied air pressure from the outside (greater than the vacuum produced) will try to make the space between the plastic and the mold as small as possible thus adapting the glass to the mold. In that process, there is many times a barrier material and an absorbent material used as excess resin is expressed. It seems that without the differential pressure, there is no further adaptation other than that which existed when the glass was originally placed in the mold. What am I missing???

Don't forget that Cirrus started out with a kit much like the prescott!

This is obviously a "dear John" post:irked: If you are into thinking outside the bun, ---have you considered controlling the rudders and brakes by an additional joy stick on the console between the seats (or in a long or veri on the other console). The linkage would not be a great challenge and can be the mechanical equivalent of the rudder pedals., left for left rudder more left for brake, etc etc. Kind of have to fly like a helicopter:rolleyes: If I remember correctly, the Wright Bros used a similar arrangement on one of their early birds. Because the rudders are used primarily on TO and landing one handed flying with the "proper stick" would be done most of the time. I would put different springing on the rudder stick so as to mentally disconnect it from aileron and elevator.

rog, need more info. did it judt come up? did you just paint? did you build? You could do an asperationl biopsy to see what is in the void (stick a large syringe needle into it, pull back on the plunger to see if it is air or liquid. the fact that it is smooth and rounded indicates to me that the top layer, be it glass or paint is being pushed from below by either gas (air or some contamination causing outgassing) or liquid. without personally seeing or touching it, my guess would be that the bubble is between the underlying glass and the paint/primer. If it were mine, I would, using a single edge razor blade (or exacto) cut the top of the bubble off and determine what is happening. if it is just the paint, decontamination and repair should be easy. If not, you will be able to assess what is actually happening and deal with it appropriately Remember, a patient that accepts a free diagnosis and treatment plan usually overpays:irked:

If you like the concept of the transponder antenna out of the brake, why not use the carbon speed brake (if needed) as the ground plane, possibly with some aluminum foil behind it for the ground plane. The only thing that you have to engineer out is the bending/stoage of the cable as the brake deploys and retracts

I've heard but have no personal knowledge that Tracy Crook uses a process where the exhaust system is coated, outside and inside which keeps the heat in the exhaust, not in the cowl. Additionally since it is also in the inside of the pipes the high heat problem might not exist. The turbo is another problem. One solution is to have a separate air floage cooling system for the exhaust system (isolated from most of the engine by baffeling) I used that concept on my d-fly and it worked well.

Ah, that makes sense. I was thinking of the old VW bus heaters.

That is what is basically used in all twins. A good system, however, in a car leakage caused CO poisioning if spotted in time is easily taken care of by opening a window. In an aircraft, not so easy. These combustion heaters in aircraft must be constantly inspected and are subject to AD notes. I would tread very carefully if you decide to use this and get a good CO monitor. The fireproofness in an aircraft is also something I would be concerned about.

Dunnknow, neil, I was always under the impression the the cap was a safety valve to prevent the hoses from blowing or blowing off and prevent the inner engine seals from leaking due to high pressue. It does not regulate the pressure created in the cooling system (more than 1 time:sad: ). Air in the cooling system has no function and should not be there as a product of proper bleeding and cooling system construction and design. Any steam that is created should be vented to a lower pressure point (header tank if the heat exchanger is lower than the engine so that the coolant is free from air. The rise in pressure is due to the expansion of the liquid due to heat. The pressurization does raise the boiling point. Just don't make your cap blow off point higher than the plumbing can stand or you will loose pressure rapidly. If you have air in the system (between the exit of the pump and the top of the engine block or in a low mounted heat exchanger, you need to get rid of it by purge or redesign. One way to design it out is to have taps at the high points of the engine/heat exchanger with small tubes to the header tank. Any gas formed will then disappear. Gas (steam) has no cooling capacity in our systems. Kinda makes me look at the waterless/pressureless system more closely