Mounting engine to VP1 firewall

[Bosvark]

The VP1 engine bolts directly to the marine ply firewall. No engine mount. I was wondering if it would be better to install aluminium bushes in the firewall to take the engine mount bolts, instead of bolting it just through a hole in the wood? The spar to wooden bulkhead and strut to bulkhead/ wooden spar all bolts through an aluminium bush (1" and 3/4") and not just through a naked hole in the wood.

Opinions?

[johnythelaw]

Hi Bosvark

My Volksplane in Swakopmund het ek nou net die VW engine uitgehaal om te vervang met n Rotax 582.
Ek gaan so oor n uur vliegveld toe en sal n foto neem van die mounting en probeer hier plaas .
Ek is amper seker dit het n aluminium sleeve met groot aluminium washers beide kante.
Plaas jou direkte mail adres vir my hier as ek dalk nie foto gelaai kry nie ( is al 60 + en effens tegnologies gesteremd met rekenaars)
Ai ons ou ballies moes van donkiekar - Ford en Chev - Army buffels en lekkende Landrovers in een leeftyd forder tot rekenaars.

groete

Johan de Wet
Swakopmund
jdewet@mweb.com.na

[Renegade2]

As with any structural or aerodynamic changes you need to know exactly what you are doing.

Unless you are prepared to do a stress analysis of the new mounting, you are best off sticking to what the plans say. Enlarging the bolt holes in the firewall to fit bushes may increase the stress in the firewall. Even if the mounting itself is stronger, it may adversely affect the rest of the structure. The wooden de Necker P props don’t use bushes in the bolt holes, but the holes never get enlarged unless the bolts are incorrectly torqued. The torque loads are actually transferred by friction between the hub and the propeller flange and not through the bolts. Although I don’t know much about the VP1, I know that Bill Evans, the designer was an aeronautical engineer and knew what he was doing. There are hundreds of VP1s flying worldwide and the design is sound.

[johnythelaw]

Hi Bosvark
Soos die manne se " stick to the plan"
Ek het gaan kyk op my VP en die gat is slegs deur die firewall sonder enige sleeve etc.
Ek heg n paar fotos aan van hoe die sg " mounting lyk.
Dit is n bout met gaatjie op die kop wat jy aan die binnekant van die firewall lock met draad aan n klein hout skroefie nadat die
enjin gehang is . Verder net n groot aluminium washer aan die binnekant dan n dikker ( so 4 mm) aluminium washer aan die buitekant
wat weer in die enjin vasdraai.
My enjin is lankal uitgehaal en ek sien daar is ook washers by wat een kant plat is - ek weet nie waar dit pas en of dit deel van die mount is nie.
groete
Johan de Wet

[johnythelaw]

Hi Bosvark
Die fotos hierbo is verklein om op web te kan sit en jy kan nie duidelik sien nie.
Mail my jou e pos addres en ek stuur vir jou duideliker fotos
Johan
jdewet@mweb.com.na

[Bosvark]

Johan, dankie. Het jou my e pos adres gestuur.

Renegade, thanks for your opinion. Was exactly why I posted the question. I am worried that the hole in the firewall will wear out but as you say. Mr Evans was an engineer and he would have known.

I will not mess with it.