| Author | Message | ||
     Larry Hoppe |
Glasair's cowling shells are joined using a lapped joint, even when hinges are used as the connector. My cowl shells only have butt joints. Which is better, a lapped joint or butt joint when using hinges as connectors? | ||
| Bill Copeland |
Larry: I don't think that there is a "better' way. Ours is butt jointed with no external screws or fasteners except inside the air intake area in the front and two screws on the bottom at the rear. We found it extremely difficult to achieve a zero gap, but after we did we painted and foune that we could not get the hinge pin in. We now have a gap of approx 1/16 in.We think the key is - in every case - to make sure whatever seam you use, make it straight or with a constant gap - at least a popsicle stick wide. I imagine that the overlapping method will be very hard to make right because of the clearances required for primer and paint. I think you will find, in the end, that the method is relativly unimportant, but design and workmanship are paramount. | ||
| jharlow |
In addition to what Bill has said, I would add that I install my hinge pin from the back of the cowling and thus hide the pin and its secured by the cowling with one screw holding the split joint together. My method assures that the pin can never go forward. Also use extruded hinge rather than rolled because the rolled type continues to open and the gap gets larger. With extruded your burnish the pin some so it slides in easy and it stays the same and thus the gap is constant. John | ||
| Tom R. Hutchison (Tomhutch) |
One of the regular's on the Lancair Mailing List, John Barret, manufactures a product called Carbinge. It is a piano hinge made out of Carbon fiber. He claims it works well for cowling hinges, trim tabs etc. His web site is: http://www.olympus.net/personal/2thman/carbinge1.htm. Looks like an interesting material. Tom | ||
| Jim Ward (Jehward) |
I tried making the same with our fiberglass, and was quite successful. I have not been able to do a pull-test on the parts that I made to determine strength. I found the process on a web page(since lost)that concentrated on building gliders. I looked all over to find a place that made them, unsuccessfully. This is the first place that I have seen that sells them. Wonder if they would be strong enough for control surfaces? Jim | ||
| Sven-Ake Eriksson (Sven) |
I have made several calculations on composite construction strength over the past years. Fiberglass constructions tend to use several more times of material needed for pure strength just to achieve the neccessary stiffnes of the part. The natural strength of a normal bid layup is about the same strength that 6061-T6 aluminium but has only 20% of its stiffness. My guess is that a well engineered carbon or fiberglass hinge would do well as a control surface hinge. The only concern is wear as fiberglass is more susceptible to wear than its aluminium counterpart. | ||
| Brynjar Thordarson (Benny) |
Honestly! What is the best way to join the upper and lower cowlings togeather? I have several ideas floating in my head, but someone, who has seen all the EXPRESSES must (secretly at least) have seen an idea that's better. I tried to put in a picture with this message but I don't know how! Rgds. Benny | ||
| Brynjar Thordarson (Benny) |
I forgot to mention that I'm using the Wheeler cowling. It fits beautifully with the MT prop I have since it (the prop) has an extention. No cutouts for valve covers or engine mount. I'm expecting you all to reply soon. B | ||
| jharlow |
Benny, I used piano hinge (extruded not rolled) and I put it in from the rear so as to hide and capture the rod. At the prop side I used phillips screws and nut plates. Along the firewall I also used piano hinge for the lower half and a phillips screw and nut plate on the bottom in two locations. The top at the firewall I also used 3 phillips screws and nut plates. Where I used phillips screws I used nylon washers. My 0.02c John | ||
| Brynjar Thordarson (Benny) |
Thanks for the info John, but as a foreigner I'm not quite sure what an "extruded" hinge is. Could you maybe send me pictures of your installation? I'm hoping that Jerry will visit the civilised countries next month and, as a wise man, he can give me some hints. What is a 0.02c? best rgds. Benny | ||
| jharlow |
Benny, There are basically two ways to manufacture piano hinge, one is to roll the hinge pin metal over which can be seen as a gap where the metal rolls back over to the flat side. The extruded hinge is one continious piece of metal with the hole installed during the extrusion process and is much stronger, The rolled is not as strong and as the cowling vibrates the rolled design gets looser as the metal unrolls slightly and the result is the cowling gap at the split line becomes more visable whereas the extruded does not and the gap remains constant. Also extruded is of course more expensive. -) Sorry for the slang of 0.02c, which is saying that is "my 2 cents worth of information" | ||
| Anonymous |
as per the aileron bell crank bracket in the wings i know there was an early bearing pressed in which was a no no , was there an upgrade on the mounting bracket? larry suggests fliping the brackets and adding spacers and a longer bolt . that is if i under stood him correctly! and the reason for this was??? | ||
| Werner Maag, CH8174 Stadel, Switzerland New member Username: Wmaag Post Number: 6 Registered: 01-2003 |
Just last monday I finally hung my IO550 N engine to the firewall and it turned out the cowling I had since 1995 from EDI for the IO360 is too small. Is there somebody with a newer bigger cowling from EAC with the 2" extension of the upper half towards the windshield to sell or is there a possibility now to get it from another source? (see how soon Gary Wolfelt's idea is coming true!) In the worstcase I had to adapt myne or make a copy of HG Schmid's one. Werner maag |