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clevelee(at)earthlink.net
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 Posted: Sun Mar 11, 2007 10:00 am Post subject: A198 Monowheel Over Center stats & anybody flying with the g |
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This weekend I too the time to disassemble my mono gear which had been assembled a few years ago. I took some measurements.
Using feeler gauges, one Port swing arm was .055" away from seating when the Starboard leg was against the stop. Doing the Trig, after grinding this down to equal seating, this provided .8 degree improvement in Over Center condition.
Allowing for the taper of approximately 4 degrees in the swing arm, measuring with a balance protractor against the arm and then the shock absorber - hanging straight down, the over center condition is now 2.31 degrees. I have not measured yet with the gear reattached, but assume this will improve slightly.
The corollary of the above is that the original position before grinding was 1.51 degrees. This is virtually nothing.
Studying the design, if the shock absorbers were not dampening well in the reverse direction, a smack of the wheel against the ground and bounce up, would allow the rubber block to snap the gear down quickly, and pop out the over center of 1.5 degrees if there were any slop or bending in the gear retraction lever. This is particularly worrisome, as how does one check the performance of the shocks - pull down on the prop in the same way you check a tri-gear's oleo? I know it's working for a lot of people, and has the blessing of the PFA, but it sure seems marginal.
I am considering locking the gear down, (which will also improve insurability) which is easily done in a variety of ways. Fairing this in would be fairly easy with a large shapely fibreglass cover. I would then operate the flaps and outriggers separately. Has anyone done this?
I guess no one knows what the speed penalty is if the gear is left down in cruise! (Unless you cruise around with the flaps down all the time!)
Cleve Lee
A198 now in Market Harborough
... and finally getting back at it . . [quote][b]
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SteveD
Joined: 09 Jan 2006
Posts: 50
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| Posted: Sun Mar 11, 2007 5:35 pm Post subject: A198 Monowheel Over Center stats & anybody flying with the g |
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Well you have the easy part done. Now your going to have to make a
new LG12 or a new retraction lever guide plate.
Any grinding on the LG08 stops really moves things around. Your flaps
downs position will also need a look.
When I redid my stops everything was out of whack.
Chat Later,
Steved
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hurstkr(at)redzone.com.au
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| Posted: Mon Mar 12, 2007 3:34 am Post subject: A198 Monowheel Over Center stats & anybody flying with the g |
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Cleve Lee wrote:-
>This weekend I took the time to disassemble my mono gear which had been assembled a few years ago. I took some measurements.
> Using feeler gauges, one Port swing arm was .055" away from seating when the Starboard leg was against the stop. Doing the Trig, after grinding this down to equal seating, this provided .8 degree improvement in Over Center condition.
Hello Cleve,
If your Port swing arm (LG08) was .055" away from the stop when the Starboard one was against the stop, as far as I can see, this would mean that there was a fairly good chance the LG08 arms were either not pinned correctly in the first place or one or both of the roll pins securing the LG08 arms is/are slightly sheared.
The important thing to check is that the two LG08 arms are in the same plane when viewed from the side. If they are and they don't both contact their respective stops simultaneously, then one of the stops is shorter than the other.
If your arms are NOT in the same plane and you have adjusted the length of one of the stops as it appears you may have, then neither the arms nor the stops will be correct.
After pinning mine the first time as per the procedure in the manual, although both arms touched the stops together, the arms were NOT in the same plane. This is when I discovered the stops were not the same lengths. Refer to my recent posting and photos.
Before adjusting the lengths of the stops, I repinned the arms to the shaft making use of the perfectly flat surface of my drill press table to make sure the arms were in the same plane. After this was achieved, I then shortened the longer of the two stops.
Cleve, like a lot of topics on this list, I think the over centre debate has reached it's climax and will now fade away. There are a lot of mono Europas flying that have not had uncommanded gear retraction problems so if I were you, I wouldn't contemplate locking the gear down. If you can positively identify any problems with the geometry in your landing gear and remove all the things that have been known to cause problems, I'm sure you will be rewarded with a reliable undercarriage for many hours to come. (Says I who is not flying yet and will probably end up eating humble pie . . . so I'll leave it to others on the list to shoot me down)
Regards
Kingsley in Oz
[quote][b]
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NevEyre(at)aol.com
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| Posted: Mon Mar 12, 2007 11:42 am Post subject: A198 Monowheel Over Center stats & anybody flying with the g |
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Attn Kingsley,
I sent you an email last week after your request for me to contact you, had no reply from you, perhaps my aol [ another one lost ? ] system is stopping them getting through ?
Try sending via John Wheeler, he can forward to me ?
G'day mate.
Nev.
[quote][b]
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