| Author | Message | ||
     Mike AuClair (Maucl1) |
What is the consensus of opinions out there concerning the need to shock mount the instrument panel? I have the sculptured fiberglass panel with the alum. inserts The mounting instructions that came with it involve shock mounts and require a Philadelphia lawyer to decipher and I can't afford one. I know that there are some airplanes flying with solid mounted panels. Are any of these experiencing problems? Thanks in advance. Mike | ||
| Reinhard Metz |
The industry concensus is that shock-mounting improves the life expectancy of gyros in particular, not so sure about electronic equipment in general. It's not so much a shock mount as a filter for higher frequency vibration. I shock mounted mine, hopefully in a manner that only requires an Illinois or Wisconsin lawyer to undeerstand: The are two mounting points on either side of the pannel, one near the top at the side, and one at the bottom. The bottom mount consists of a pair of rubber mounts, (the kind that have a treaded stud out both ends), that sit between a horizontal flange on the fuselage side, and a mating flange on the bottom of the panel. The pannel is the articulated type, which curls around at the bottom, creating a natural horizontal flange area. In other words, these mounts are under compression, so you don't need to worry about them busting and the pannel falling into your lap. The upper two mounts are also the rubber vibration isolators that have studs, and are on the back of the panel, perpendicular to the face of the panel, a pair per side for failure redundancy and strength, with the back studs going through a vertical flange again on the side of the fuselage. These two mounts operate in shear. In addition, my bottom mounts are actually not directly on the pannel, but rather are on a hinge mounted to the pannel. This allows me to loosen the upper mounts (requires reaching underneath in some contortion) and pivot the panel back about 50 degrees, making installation and future work much easier. Of course, all controls and cables must be routed, bundled, etc. to allow this pivoting. Reinhard Metz | ||
| Jim Butler |
I'm disappointed Reinhard. This is where I thought you would have put in a plug for balancing the prop. ;-) | ||
| Reinhard Metz |
Yes!!! Jim is so right! Balancing the prop is very important, although I think more for the engine and engine mounted component's sake. Like the exhaust system, which in my case kept breaking until Jim came along and helped me out with the balancing! | ||
| Jim Butler |
The Navy did a study on their fleet of P3 Orions, half of which had the props dynamically balanced. The mean time between failure of several different areas of the aircraft were monitored. The time between failure of the avionics went from around 150 hours on the unbalanced aircraft to over 300 on the balanced aircraft. Even things like fuel tank leaks reduced dramatically. Vibration is insidious and reduces the life of every component in the aircraft. Just as we can only see a small spectrum of the light frequency, or hear a small spectrum of the sound frequency, we can only feel a small spectrum of the vibration frequency. However, even if we can't feel it, it is still robbing the fatigue strength from everything it contacts. | ||
| LOUIE LACY (Llacy) |
Tom Why am I getting the same message at least twice in my e mail | ||
| Mike AuClair (Maucl1) |
Reinhard and Jim, Thanks for the input. I believe I will proceed with some type of dampening system. Makes sense to me. Mike | ||
| Kevin Dennes (Kdennes) |
I am building a 2000 and near the point of having to make a decision as to whether I should install the windshield or the instrument panel first. Larry says that different builders have differing opinions on this. I would be grateful for any input on this please. Kevin (from Downunder) | ||
| Jerry Sjostrand |
Hi Kevin, If you can create a flange into which the windshield will install (per Glasair) then you should do all your instrument panel work first. I put my windshield in first and then did the panel. It was not too bad but certainly would have been easier the other way. Creating the flange can be done by cutting away the outer skin but leaving a flange area of 5/8" to 3/4" on the innner skin around the windshield opening. Then you must build it up with resin and milled fiber (or ?) to accomodate the thickness of the windshield minus a couple of layers of fiberglass cloth which will be put on the outside overlapping the fuselage and the windshield after it is squished in place. Again, Check the documentation for the Glasair installation for the details. Any other comments would be welcome as this is an important consideration for any builder of the older kits. Cheers. Jerry Sjostrand | ||
| Tom R. Hutchison (Tomhutch) |
I decided to leave out my windshield a long as possible to make forward fuselage installations easier. I Probably will install the blank panel before the window goes in. Larry recommends having the windshield installed before hanging the engine. The 2000 series fuselages have a joggle molded into all the window openings for installation of the windows. I can see how this makes installation MUCH easier than the original Expresses. I was just visiting with a local award-winning Glasair builder yesterday and found out how Glasairs have their windows installed. He installs his windows from the inside. First he grinds a 1" area around the window the depth equal to the outer skin. When the window is installed this puts the window surface perfectly flush with the outer skin. Looks very nice but a hell of a lot of work. Tom |