Rotax 912 planning – Cowl

Niw the engine radiators and exhaust are in place in the mock up jig we need to get much more accurate measurements for the proposed cowls.

The recent photos from Christophe in France have been a great help and will defiantly assist the next steps over here in England

The best way to get accurate measurements is to remove the Jabiru engine and so provide a better access to the clear bulkhead areas

I normally remove the engine from the engine frame but this time it seemed better to take the engine plus frame as one

Tricky keeping the exhaust and oil radiator in situ and taking it down to floor level safely.

Post this removal, the guys from Competition Fabrication will measure after which I can refit the Jabiru whilst the cowls are built

Way back …

Its a time of tidying up and making sure ive got copies of things before deleting!

Way back … this was a series of shots that the factory put out to show jist what you received when you embarked on such a programme !

The undercarriage with plates and bolts and tyres and tubes … now, 10 years on, some of these bits have been replaced .. a bent leg (following a tow by the Jersey Airport firecracker over a speed bump !) .. at least 3 sets of new tyres .. all that taxying at Jersey wore the tyres out …

Plus done new rubber bungees post the baby oil from the smoke system making them all floppy!

Elevator parts … i ended up thinking I needed to use the whole curved trailing edge ! .. so I now officially have the largest Sherwood Ranger elevator ! Great .. flies hands off !

Cap loss

Over the years ive lost many caps.

The first was over our house in Jersey .. flying with my son … pulling the aircraft around to stay in focus on the house, your instinct is to pull your head back and start to look for the ground to the side and below you.

Eventually, you bring your head back into line and, invariably, raise your eye line

This has the effect of getting a smidgen of wind under the peak ..and woosh … the cap is gone

The first one ended in a field and was never found

The one in the pictire above was in the bay of St Ouen just off runway centreline. Id been asked by a local commercial pilot if I could do a fly by of his wedding reception.

Stupidly (ney Honestly) I advised ATC that I was doing 2 fly pasts, offshore, N of the runway centreline. At the hold and about 2 minutes to the scheduled reception time, ATC advised they were holding me whilst they decided if this constituted a ‘flying display’ !

Minutes passed … and eventually I was cleared to line up

Pulled up and right.. a sort of part heading towards Guernsey, and could see people just coming out for the reception. I peeled over and around (this era was pre smoke .. which sort of would have classed as a ‘display’)

I think this was one of the first time I flew through my own prop wash in the Ranger. It was VERY pronounced and getting a rather large dip whist about 500m offshore was quite alarming …

Pulling up and away into a turn and this shot shows what happened to the cap ! Never to be found again !

A more recent one was in Norfolk .. about September 2025 … just departing with my son and into the circuit and turning to see who was departing behind us .. cap went and I thought oh no not another …

As I looked around.. in the small rear view mirror I have for the smoke system, I could see the cap was wrapped around the tailplane rigging!..

We pulled around onto a long gentle curved approach..trying to keep the cap in situ

All was fine until the round out .. and the change in air flow and reduction in power ..and off it flew.

We touched and I left my son in the front on tickover on the ground whilst I ran back and jumped the ditch and across the field to retieve !

First save ! ❤️

Approaching 500 landings

Ive been tracking all landings since the build and its approaching 500 … but not quite there yet !

As at this morning I needed 54 to make it to the 500

Planned some teardrops out and back to speed up the circuit times but then realised id be passing a couple of houses on both outbound and loop back to the opposite approach.. so they woukd get the noise both ways ..

Rather than attract some adverse feedback I opted to do around half and mix with some full size .(normal) circuits..

Just as I got in i discovered that a mouse had managed to chew it’s way through my cap that I leave in the aircraft ! So, a very cold flight of 26 circuits with a blast of icy cold air and only a small headset to fend off the blast !

Grab a sunny day when you can

John and I had discussed a formation sequence a few weeks ago but he saw we had a nice weather window this week, so we planned to meet and pre brief.

We agreed method of lead and follow… when and what frequency to switch to and what actions to take if anything went a bit odd.

John’s new 360 camera was a great new add on and so we were using this flight as a pre test

Winter (pre) starting

Another classic Autumnal weekend with cold and damp mornings.

Saturday was blowing a fair bit across so decided to wait until Sunday.

I had a small maintenance job to do first, so put the heat gun inside the cowl and put the top cowl loosely in position.

This would capture all the warm air inside the cowls and warm the sump, oil and carb as well as heads.

The small repair job took about 5 minutes, I have 2 RPM guages.. one is the original multi MFA unit (green and black display), then other is a newer version but dedicated to JUST RPM. The 2nd (newer) one had been in about 4 years or so, had started to go on and off intermittently.

I had traced it to a bad crimp on a ring connector that was one side of the 1 amp fuse. Undoing the fuse to save pulling the panel forward, gave easy access to allow a new ring connector to be cramped on.

5 minutes had clasped so quickly screwing the top cowl on, pull out (with Bob’s assistabce) and she started on first turn of the blade !

Damp and cold starting

Id organised a group fly out .. not too far .. just Tibenham (literally next door) and Great Oakley

As it was Rememberance day and a memorial service at Tibeham we needed to be on time

For the first time ever i think … the Jab refused to even fire

Not one cough .. just cranked until.the battery eventually went flat .. leaving it to cool between cranks !

Subsequent return a few days later .. batteries recharged and a heater used ro chase away moisture and damp PLUS a small singe squirt of easy start amd BOOM .. into life !

Clive (James) one of our super helpful and friendly club members .. also very experienced in Jabirus .. offered some useful.fine tuning advice

On a Bing carburettor (commonly found on BMW Airhead motorcycles, Rotax engines, and some snowmobiles), the idle mixture screw controls the air-fuel ratio at idle by metering fuel into the idle circuit. • Turning the screw IN (clockwise) restricts fuel flow → leaner mixture. • Turning the screw OUT (counter-clockwise) allows more fuel → richer mixture.To make the mixture richer: Turn the idle mixture screw OUT (counter-clockwise).Standard adjustment procedure (for reference):

1 Warm up the engine fully.

2 Set idle speed slightly high using the throttle stop screw.

3 Turn the mixture screw in until the RPM drops (too lean), then out until peak smooth RPM is reached.

4 Typically, the richest smooth idle is found ¼ to ½ turn out from the peak RPM point (to avoid running too rich and fouling plugs).

5 Reset final idle speed.Note: Some Bing carbs (e.g., Type 53/54 on BMWs) have the mixture screw on the side; others (e.g., Type 64 CV) may have it underneath. The direction is consistent: out = richer.

Rotax – Progress

Now I have the shiny new permit for 12 months.. time to consider 2026.

The great work by Competition Fabrications has got the exhaust pipes neatly tucked in and both oil and water coolers neatly positioned

Next stage is to consider what options there are for cowls

The ideal would be nice curved alloy ones but price could be expensive … need to get some measurements to progress planning

The depth of the planned eProp is much less than the Hercules wooden one so that brings the front cowl much closer in and closer to those hot exhaust stacks

Ideally we need a hinged top surface cowl .. that can open both sides and secures against bulkhead and nose cowl

Permit awaiting and impending storm

Waiting for the full permit .. BUT LAA have signed off and approved the repairs and the test flying that accompanied it !

With a hefty storm (Benjamin) on the way .. there was a smallish window on Sunday to get a last flight in before wind and rain spoiled the next 7 to 10 days 😞

With the new (front) battery in the start was pretty much instant .. but drizzle was definitely just a few minutes away ..

Decided to make it a pretty quick and short session.. once pul temps were up to 50 and the preceding aircraft had landed (such a quiet strip.. and you go to line up and someone’s on long final!).

So, with 2 teardrops from 01 (take off) and 19 (loop back) to land back the other way, and repeat the other way … managed 4 landings in 9 minutes .. bringing the total landings for the Ranger to 436 to date.

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