Mast Compression

[albinvega1865]

Whoops! Should have asked this question prior, but does anyone know what the proper pressure should be for a fuel pump for the Vega and its set-up?

Chris



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[rchrdcoe]

Chris-
It's located up under the cockpit seat. The bracket I fashioned is
well fastened to the bulkhead.
Richard

 

[albinvega1865]

I like that idea Richard!

Thanks again for your help with this...now I just hope that the pump I have is the right pressure. I have heard not enough will not get the fuel there, and too much can be equally is disruptive to the system. What is a common pressure for a system like this? 2-5? Any idea?

Chris
Richard coe.richard@... wrote: Chris-
It's located up under the cockpit seat. The bracket I fashioned is
well fastened to the bulkhead.
Richard

 

[zaza_sese]

Hi Steve
This is an interesting chat.
I agree the area where vertical load should be absorbed is the bulkhead. However, this does not necessarily happen for a few mechanical reasons. '
One is the way the mast beam is joined to the bulkhead, which is relatively uneffective being partially based on transversal loading the mounting screws, partially on friction (sandwich effect).
Another reason is the preload the constructors apply between the door sides and the same beam (you see the way it's done by removing the cover on the aft side). If there is preload, that necessarily means a part of the compression goes through the door sides. How much depends on the flexibility of the structure above (bukhead + beam), as you seem to point out too.
The axial rotation of the mast beam is the proof that such loading effect is relevant. If the constructors did not want any loading effect on the door sides, then no preload would have been applied. You can well see what I mean by drawing a simple model of the structure.
The effect can be, as you say, the sides touching the floor, and/or the sides bending inward (their section form factor does not help much against that).
Replacing the beam sandwich is the thing to do, but one can (should) also take advantage of the robust structure of the floor underneath the door (the way it is structured makes me think again that there was an intentio to delegate some pressure to that).
That's why I changed the door sides too.
After applying my solution I measure unrelevant vertical shift of the bulkhead surface underneath the mast even in the worst conditions.
Cheers,

zaza
To: AlbinVega@yahoogroups.comFrom: steve@...: Thu, 25 Oct 2007 09:30:23 +0100Subject: Re: [AlbinVega] Mast Compression

Hi ZazaThe mast support is not via the two vertical door sides. The actual support is taken via the whole main bulkhead. The first sign of mast compression is the door supoports touch the cabin sole (floor).CheersSteve B