Been a very busy Easter weekend 😀

Filled her up to the top and set off for the endurance test .. the wind was a cool breeze varying 12-14 and around 30 degrees off the 26 runway

Knowing how cold I got in the stall tests the other day I had my full ski gear on underneath.. long johns and top as well as a T shirt plus a fire retardant top I bought ..Same one Williams used for Bottas last year and then a jumper and then the flying suit !

Feeling a bit like Michelin man I clambered in .. some people pay a lot of money for gym membership .. I get in and out of this ‘plane in seconds exercising both legs, arms back full upper body .. and not a trainer in site 😀

The breeze made the tail lift in a nanosecond and airborne in 2 nanoseconds …

Up and away to the SE corner of Jersey and decided to re run the power climb tests .. the sea looked Caribbean (shame I hadn’t cleared the go pro down as the next 2 hours of wing over shots to show the island in all its glory were lost as the camera stopped before I actually started taxying ! Doh ! )

Climbed up to 3000 and then decided to throttle back and just ‘mooch’ I think is the word at around 2600 rpm and she just floats around and around almost losing no height at all

I then thought I could use the descent to check the VNE handling … so wound down a bit … told the tower my plans as I didn’t want them worrying me suddenly dropping off radar !   Then pushed gently forward … I eased the throttle back so as not to overspeed the prop

As usual .. first attempt .. I was too timid and she went down but nowhere near fast  enough .. the ground .. well sea .. loomed and at 800′ I abandoned it and elected to go back up and try again

Back up to 2000′ and pushed again .. it needed to feel more vertical and the classic view of the world filling the screen ! Lots of rocks and sea !! The speed wound up and she felt absolutely solid .. the Stampe used to whistle as it had solid aero shaped bracing wires and these used to ‘sing’ as you plummeted .. it’s not something that I particularly enjoy .. as you start thinking of those dinky little wing bolts and those bracing wires you made 2 sometimes 3 times .. until you were happy but THIS is the moment that you made and re made them for … this 10-15 seconds !

I eased out of the dive and the ‘plane felt a dream .. my EGT had gone haywire and I need to check with PHS why that might be .. one theory is that the mixture leaned on the dive ?I did get a face full of fuel on the initial pushover as the nearly full tank exited through the breather hole but had that happened once before and it’s no big deal as it stops as soon as you level out

I then proceeded around the island to crank up the 2 hours …so around and around I went.. the EGT eventually settled down and all other indications were fine

About an hour in the tower asked if I was wanting to come in from the NW corner for landing but advised another trip around was needed. SkyDemon says I did 86 miles .. ok a lot of it was straight up and straight down vs flat in line 😀

At the 90 min mark I couldn’t feel my toes as it was pretty cold so pulled my legs back in turn to flex them and get the blood moving !

Eventually I thought it might be prudent to get back into the circuit – even if not to land – as I don’t know the exact fuel burn yet

Did a go around and then as the 2 hours came up called for landing .. guess what .. you are number 5 to land ..

Its not often I have made the next call .. in fact never ! I didn’t actually call a fuel emergency but said that this was an endurance test .. it was now at the END of that test and pretty please could I NOT be 5th !

Tower were great and I got bumped up to no 2 and asked to follow the ATR in … i was zigzagging to make the 4 mile vortex spacing but stay as close as I could to the beach ..

Rolled onto final as the ATR vacated at the end and purred down the final approach .. tower kindly gave me two wind checks as the wind was now a steady 14 slightly off

Side slipped down hoping my toes would not behave like the blocks of ice that they felt and I could get her in wing down and hold off for the landing .. on checking I reckon I had 30 mins fuel lefT

Footnote – 24 hours later – got her fillled and she took 30 litres .. proving I had 10 left in the 40 litre tank .. so looks like endurance of2.5 hours although will probably normally do 1 hour stints then fuel up 😀

Many many months ago , when I first performed taxi testing I found I had trouble getting around some of the tighter angles in front of the hangers at Jersey.

The way around this was to disconnect the steerable tailwheel and this has been absolutely fine and let me turn the aircraft on a sixpence for parking

There was one slight issue i noted ,, when looking at a go pro footage in November when I spotted that if I let the tail down super gently on landing and it touched then left the surface then it had a propensity to spin around

In November it simply snapped straight on the next touch …

Last weekend .. it appears the same happpened  except this time .. as the tail wheel touched a second time it was at 90′ to the direction of travel

The wheel then jammed and my 1/4 mile taxying flattened the wheel at one side eventually ground through the securing bolt as I pulled  into the aeroclub

Continue reading “Free castoring tailwheel – Considerations” →

After landing following the last hot running circuit I contacted Paul in Norfolk

Paul kindly got a couple of other builders with the same (Jabiru) engine .. Charles (UK) and Rool (Holland).

The cooler fittings looked very similar but, on checking the sizes and also getting some pictures from Danny B it was clear that my cooler size was hopelessly undersized.

I thought back to why I had sized the cooler the way I had … It was the thought that I wanted to try to fit it into the under belly scoop … This sent me down a route that left me with an oil cooler that was nearly 4 times too small …. My surface area was around 11,000 sq mm … Danny and Rools were over 45,000 sq mm !

Danny sent me a link to the one he bought and I ordered it that night .. Duly arrived 3 days later

Rubber grommets for anti vibration

Fitting it was fun as the lower cowl needed opening up a little more

Now to work out pipe new routing

Will have to do some lower cowl patching and filling before tidying up and then re spray

Ready for test run and then build a shroud to protect and shield the new radiator

Right … that didn’t work ! still hot

2 more (cross country) circuits were planned but she was up to 115 by the time I got to finals on the first circuit so changed it ‘To Land’ .. getting lots of take off and landings in though ! – always look for the positive 🙂

Having seen the other examples I will remove the top duct rubber to allow the air to flow in above the new cooler matrix and then get the whole cowl touched up and repainted once tests prove ok.

Thanks to all for their kind input and advice …. makes it so much better 🙂

One other thing I did on this short test was to start to try the tests that Howard (Barber) had suggested … I did a nice wingover on departure into the circuit – which felt great … then downwind I let go of the controls .. fine .. then I pushed full left aileron and let go … just a gentle bob back into S and L ,…. then the same to the right .. such a joy to fly this aircraft ….

So, back on the ground and a hot engine .. 😦

Calls to Paul and Danny ensued over the following 24 hours

Bingo …. with input from Paul and Charles and Rool

Looks like the cooler i’m using is hopelessly undersized ! – Now I’ve thought back and this didn’t get delivered with the engine … I remember simply measuring the gap of where I planned to locate it .. ie the scoop under the belly and then buying one to fit. Not very scientific but I’m not sure I have seen a spec for a ‘standard’ size in the Jab manual.

It turns out that Danny and others have one that is around 300mm x 140mm x 40mm

Mine is 140mm x 90mm x 50mm – so probably about 25% the size of Danny’s !!

Danny kindly dug out his spec order number and I am now awaiting the shipping to Jersey – hopefully 48 hours

Rool had a neat idea of making a front shroud for the cooler .. protects and also acts as a gurney to create backdraft and suck the air out … so have a sheet of nice aero metal (thanks Graham CIAS) and that will go on after the next test.

Well … this has proved to be quite a challenge as the art of cooling – without the aid of a £1m plus wind tunnel makes it a little trial and error … perhaps Benjamin could sneak a mornings use of the Williams F1 tunnel and that nice long smoke pipe that would really let me know what the airflow was doing 🙂

Anyway … back to chalk and board .. as my first instructor used to say …..

In this case its drawing on experts like Paul HS and Danny B who have been really great through my current challenges and have certainly kept me going with this ‘long distance’ OU style course in aerodynamics.

As you can see from the previous blog entry I had failed to shroud the intake area around the oil cooler matrix – Now done … but … 2 Jersey style circuits (around 6 miles !! – EACH ! ) and it proved to not fix the problem and temps still crept up above 100.

Plan B – was to relocate the underbelly mounted cooler to the front of the ‘plane – right behind the prop .. that should def fix it as there was nothing in the way to prevent a good solid flow over the face of the matrix .. either that or it would demonstrate that THIS wasn’t the problem so at least move me on to the next option.

As you can see in the background of the picture I had to ditch my nice braided oil cooler pipes .. once I have established a proper fix I will get some new ones made up to whatever length / shape needed.

I made up some mounting brackets and moved the old oil cooler into position

The cowl then took some definite slow and steady fiddling to remove JUST as much as was required to get the cooler AND its pipework in position. Then, with some new wider ducting tape/rubber fill the gaps.

Took the opportunity to remove the original engine top cowl ducts and replace the rubber strips with wider – needed as earlier ‘fettling’ had meant I now had some small gaps between cowl and intakes

T

Always an excitement to wheel her out for flying ..

Whilst the windy weather has held further testing back I have had chance to share some pictures of my cowling and front end intakes with Paul HS at TLAC.

The upshot is that my original design for the oil cooler housing underneath was not sufficiently shrouded to force the air through the cooler matrix.

The  setting I had in place left the passing air too much option to simply go by the side or over the top of the matrix !

Have now made two significant changes

• Add shaped deflectors and shrouds on the front of the matrix
• Move the matrix back 2 inches
• Put rear turbulator strips on the rear of the oil cooler tunnel

ok …must learn to count .. That’s 3 things !

The setting back of the cooler provided a nice stepped inlet to focus the airflow

The deflectors have been added .. One each side and a larger on top. These have been cleco’d for now so that I can test them in flight before securing with rivets

The rear turbulator strip encompassed two sides and the Lower edge and present about a 1″ face to the airflow and so should create a reasonable back pressure and support the ram air by introducing a suck from the rear …

Testing due this week and should be proven in two circuits !