Finally – Smoke stress test completed

This part has certainly not been easy … to stress various values ends up putting parts of the aircraft at risk of being damaged if you don’t do it really carefully…

Given a max weight of oil tank, plus pump plus a full load of (baby) oil… the all up (unit) weight is 19,7kg .. you then need to cater for Forward factors of x 9 … side to side of x 4.5 and vertical of x 6

So Forward is a mere 177.3 kg

Side to side is 88.65 kg

And vertical is 118.2 kg

Will and I decided to removed the front windscreen to prevent any accidental damage caused by a straining strop moving and cracking !

And the 4 stainless turnbuckles that secured this so tightly held rock solid …

Also checked none of this impedes any control movement or even getting in and out !

Windscreen replacement

With lots of people being taken for the odd little spin up and around you are bound to get the occasional problem …

Last weekend we had a short lean forward in the front seat to get comfortable before I strapped the passenger in and crack .. front screen cracked .. top to bottom

They are quite resilient .. but press them just in the centre a little too hard and …

Protective covers off
Love new screens .. it’s like there is nothing there .. so so clear
Nearly there … not too bad .. less than 40 mins

A nip out with ATC

Had the pleasure of a short trip and some circuits with one of our Senior ATC guys today .. Alan Moss …

He is also a keen photographer as you can see and flew some lovely tight circuits over Havre de Pas and Green Island before heading back for a touch an go followed by a close bad weather left hand circuit off runway 26

Hello Tower 😊
Corbiere lighthouse
26 Left base

Smoke oil tank fixation ! Ver 3

By ‘fixation’ I mean getting to a design that is simple .. neat.. quick to install .. quick to remove … BUT .. will stand the test of the required LAA 9g stress test !

I am really happy with this one … clean and simple … looks right

First (ground based) smoke test

With such a sunny weekend it was a good day to remove the front seat cushion and part fill the smoke oil tank .. about 1/5th full .. so enough to cover the ‘clunk’ tank internal feed pickup.

A ‘clunk’ pick up is like my model fuel tanks from when I was a kid .. it’s a pipe with a weighted end so that it always gravitates into where the fuel lays .. technically it means it will still pick up when inverted !

I did an initial ground power test outside the hanger .. fire extinguisher at hand … this proved that none of the feeds, or t bars or injectors had a leak. So we decided to ring the tower in advance of an engine on test as the smoke would, by virtue of where we were, drift across the upwind end of the active (only) runway

Took a bit of explaining as it wasn’t simply a ‘around island check out’ but the ATC kindly humoured me and asked if I wanted fire crew on standby … I felt it may be over the top but didn’t want to dissuade if they fancied a ride out in the sun

Sure enough .. the super helpful fire crew turned up 5. mins later in a land rover check vehicle and a super large bright yellow spray vehicle !

Initial start up and run up to reasonable temps and i selected smoke on.

Will was videoing and had a headset on with the icom standby radio so we could communicate if required. With a thumbs up and smoke on .. nothing was coming through in terms of smoke. So we stopped to investigate

All looked fine but we thought we would break the connector feed and see where the ‘blockage’ was … turns out it wasn’t even making the injector side of the on off valve !

On more detailed inspection it appeared that the one way STOP valve had an arrow on it and it seemed to indicate ‘direction of flow’ and, if so, it was facing the wrong way

A quick break of the metal hard jubilee clip and re jig and re clip with a longer piece of test drain tube .. re open stop valve and turn master on, pump on … and loads of oil !

At this point I walked the firecew through the setup, fitting, switches, safety valves and planned securing method with braided steel tie downs. They said they were very happy with this and would welcome a copy of the spec for their records with some details of oil formulae

Reconnected the system to the aircraft pipe and injector feeds and back in to start engine … ran up to around 350’c and try again … smoke was evident but fairly whispy … tried to up the power, temps but at ground level and not full power it was never going to each the 600-700 of normal operating temp .. so shut down.

Another ground test we carried out was a timed on, off test turning off the continuous button and noting when the (albeit light) smoke stopped … it was almost instant stop .. very clean .. so that’s quite a result as well .. with no delayed residual left in the pipes

At least it all functions and no leaks 😉

Post test investigation revealed a pretty wet bottom … the unburned oil had blow back on the undercarriage and front underside … I suspect at operating temp it will pretty much burn off !

Smoke system – securing

The LAA have asked that the smoke oil tank is secured suitably to withstand .. wait for it .. 9G …

I had planned a slightly more complicated cross over bar arrangement as this would match the aircraft internal structure but then thought … hang on .. this is a bit over engineered

I needed something that was simple to fit .. easy to remove .. easy to stow any elements that would stay permanently in the aircraft and yet be really strong.

The rigging setup on the Sherwood is a,azingly string and yet simple to manufacture so .. decided to use 3mm multi core stranded steel wire .. thimbles and turnbuckles to give me some ‘fit and secure’ flexibility.

All parts are stainless or steel … and it was fun to borrow Bob (Wright’s – CIAS) nicorpess huge pliers again … 3 tonnes of pressure when swaging.

… the quick release crampon means it should be a very neat cockpit fit with no loose flapping bits.

I also started to connect the jumper cables on the switch, fuse, switch and relay … as I have co located the fuses and switch the wires can be cut down to cm …

Just need to decide if I’m going to mount the ‘momentary’ switch to the stick … this is armed once the main smoke switch is thrown … cool eh 🙂

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