lee-wave

Check this one out .... colleague has had one fitted in an SK for the past 10 years with no problems whatsoever.   

Shorai LFX21A6-BS12 12V Lithium Motorcycle Battery Inc Free Delivery | MDS Battery 

Has anyone got any ideas where I could mount some 50mm machine guns on the Jabiru.   In the event of an invasion the Jabiru owners group are thinking of a last line of defence ... you know.. something like the home guard in WW2.   

5 minutes ago, horsefeathers said:

Thanks to all for the responses and info.

I've tested the sensor, and according to the info on the web, and the testing procedure, the sensor is dead. 

Jabiru pointed me to a supplier of the sensor ($200+  - YIKES), as they are unable to supply a sensor at what they call a sensible price.

 

I'll order the sensor later, and see how I go. In the meantime, I'll try a tiny tacho as a substitute.

 

Before you purchase the sensor at such a ridiculous price check this out....https://cpc.farnell.com/multicomp/mcpip-t12l-001/sensor-m12-pnp-shielded-no-2m/dp/SN36994?   It should work.....

The highest recorded wind gust of 122mph was recorded at the Needles 2 days ago.  On the farm we recorded a gust of 68 mph.   I had tied down the Jabiru with extra strops and a strop around the tail pulled tight to a tree directly in line with the fuselage. The Jab is one of the very few aircraft that would survive such a battering out in the open.   The windsock on the strip has vanished.. probably someone in Denmark will find a windsock wrapped around a tree..

Around the rest of the country 3 people were taken out by falling trees, the O2 arena in London had part of its roof ripped off, many thousands of trees toppled over, many houses damaged. Even a huge wind power generator was blown over.  It's not completely over as today, Sunday, there are further warnings of 60 mph gusts.

Ah well at least the winds may blow all the bugs away ....

Cold Start Notes Jabiru 2200.doc        

On 08/01/2022 at 2:19 AM, Alan said:

Jab 230. Engine Gen 3 with all latest mods (18 hours since overhaul). Running on BP95 Auto Gas (Avgas is now too hard to get) . CHTs pretty even and don't exceed 170°C.  No previous problems experienced. 

 

Until a few days ago - Air temp 35°C, all checks normal, put out taxing call and held short of runway while student in 150 landed who then came in off the runway onto the taxiway and turned back towards the runway in front of me.  Then I waited and waited while monitoring CHTs. Eventually the instructor got out, gave me a wave then leaned in to the door for further chat.  OK so a student doing a solo.

 

What this meant was I was idling for about 15 to 20 mins total, but the CHTs all looked OK.  The student cleared and I back tracked and took off.  Just after rotation (app. 150-200ft) my engine started running really roughly, revs dropping and loosing height. I was preparing for a cane field arrival when sufficient power came back to hold altitude, not too turn back, but I had more options.  After gaining circuit height I prepared for a normal landing, but with a now normal engine behaviour, I gained further height but remained local within gliding distance of the airport. 

 

Plugs, leads, filters checked. Fuel checked for water and any solid residues after evaporation and then donated to the lawnmower.  The engine has behaved normally for about 5 flying hours since.  

 

Lesson learned, I was not far from flattening the sugar cane. I believe the rough running was a vapour lock caused by the long waiting time and high ambient.  I had the electric fuel pump selected and could hear it running. 

However, I was thinking it would be pretty simple to set up a temperature monitoring of the firewall forward fuel lines, possibly on the inlet to the mechanical pump or inlet of the carb, but what temperatures would be regarded as critical?  I'll take some of the fuel into the lab and look at its boiling point but that would not test actual vapour pressure nor allow for the 4psi of the fuel system. 

 

Any thoughts out there?  

More then likely carb icing due to prolonged running at idle.....

The article was discussing why, in a flat turn, the outer wing rises.  This effect is commonly referred to as the secondary effect of yaw in an aircraft.

The ‘distance’ the inner and outer wing travel in a turn is irrelevant with regards to the outer wing creating more lift.

It is the ‘difference in airspeed’ between the inner and outer wing causing the outer faster travelling wing to create more lift.

Consider the following:

·         A Jabiru UL flying at a 100mph

·         A rate one turn (180deg in one minute)

·         Wingspan 10mtrs.

With these figures the difference in airspeed between the inner and outer wing is around 1%.  The lift difference between the inner and outer wing is around 2% .

Things become a lot more interesting if we now carry out a steeper turn say a 90 deg turn in 6 seconds at a lower airspeed of 60mph. 

If you do the math the difference in airspeed between the inner and outer wing is now around 4%.

Since lift is a quadratic function of airspeed the difference in lift between the inner and out wing would be near to 9%. 

This is one of the main reasons why, in a long span aircraft such as a glider, there is considerable amount of bank ‘hold off’ when turning steeply either way in a thermal.

A bit similar to this incident at the Cambridge gliding club in 2019.... 

https://assets.publishing.service.gov.uk/media/5f44d22cd3bf7f67afe3052b/Jabiru_UL-450_G-ROYC_05-20.pdf

As with all types of aircraft, both taildraggers and nosewheel, stick well back on touch down, keep looking straight ahead and maintain direction with rudders.   The flight is not over until the aircraft has stopped.

18 hours ago, Bruce Tuncks said:

My son has a Lancair, and according to most , has done a harder training course to fly his VH Lancair with retracts.

Here's my question.... could he ( in theory ) fly my Jabiru solo? What are the legalities?

In the UK the SK is classed as a Group A so it is legal to fly it with a PPL or NPPL with SEP endorsement.  It is strange that with my NPPL (microlight) I cannot legally fly the SK which is an identical aircraft but does not meet the stall speed requirement for a microlight.

14 hours ago, RFguy said:

And, Jabiru engines rely on the bores and head and crankcase all up to temperature  (expanded) to get the Thru-Bolt preload up to what is necessary for a full smoke takeoff run....

With all due respect RF this is the most ridiculous statement I have ever heard about a Jabiru motor and the thru bolts, even if it has been written in the Jabiru manual.  First of all what is the temperature that the bores, head and crankcase need to be at before applying full power ?  Secondly how would you determine those temperatures. The only temperature gauges available are CHT, oil temp and EGT. 

The recommended way to warm the 2200 motor is to start it and idle at around 1500 rpm for a few minutes.   Then taxi at a fast pace to the pre take off checks holding point.  Oil temperature needs to be at least off the lower stop (around 50C). Carry out the checks line up and takeoff.   By design the best cooling of the motor takes place in flight with the airstream moving through the motor.    Idle too long on the ground in an attempt to warm the motor up is the shortest path to its destruction... 

On the subject of fuel in other postings...I use Esso Synergy 97+ mogas.  With absolute certainty there is zero alcohol added,  at least here in the UK.   If uncertain about the alcohol content in petrol adding water to a sample will draw out the alcohol content. 

Pour 10 ml  of the fuel in a  50 ml graduated cylinder... then 2 mls of water ...shake for 15 minutes.   If there is no alcohol present then the separation line will be at the 2 ml mark. If the separation line is above the 2 ml mark then there is alcohol present.  I did a test on the latest crap E10 fuels been supplied on forecourts.   It showed around 9 % of alcohol added.  Not good for combustion motors, fuel lines carburettor, seals etc.....

Thanks for the replies and some very interesting links...

After some research and as discussed in the comments above VNE in the Jabiru (120knts) is max permitted IAS.   This airspeed is about 10% below VD which is the maximum design airspeed.   This provides a healthy margin of around 15knts before reaching VD.

So it is safe to dive to 120knts during the annual permit test flight at least below 5000ft.  Thereafter when flying at 120knts above 5000ft TAS gets very close to VD.   

There is no law that prohibits an aircraft flying off and landing on private land, so the simple answer is yes you can operate your aircraft but common sense applies.... such as noise abatement, no beat ups, minimal circuits etc.   I think this applies to any country, it does here in the UK...

Weather radar is not a perfect answer to bad weather avoidance.....it is a known fact that wet snow and rain show up better then dry hailstones.  I don't think there is a single pilot who would knowingly fly into a severe storm.  These situations will continue to occur and maybe increase as the climate moves into ever increasing turmoil....

Superb video of an IFR flight in a 182T   

On 19/05/2021 at 11:00 PM, graham brown said:

Biting the hand that feeds you? I threw my Borgelt vario away years ago.

Cheers a “not even a bootlace”

(who has not killed anyone in 30 years of instructing and volunteered my time for nothing.)

I quickly checked in my log book dating back to 1970...it appears I have not killed any of my students...although there were quite a few that I made puke up....  'not even a bootlace 2'....

17 hours ago, Mike Borgelt said:

Just countering the stupid theme that these folks handling emergencies had a better outcome because they had flown gliders, in many cases in the distant past.

It would be equally stupid to say that the gliding experience of the pilots involved in the abovementioned emergencies had no part to play in the successful outcome.....

The only way you can gain a real increase in performance without modification or weight increase is to put on a more efficient propellor.  Fitting a 60X40 in place of a 60X42 results in static revs increasing from roughly 2670rpm to 2890rpm which is equivalent to a 7 % increase in horsepower (I think the maths is right) .Certainly the take off performance is blistering... but the offside is there is a reduction in cruise speed ...

Just downloaded the SafeSky app .... looks very interesting... 

20 hours ago, Bruce Tuncks said:

Here's a puzzle I need to sort out...  On the last 2 starts, the engine has fired up almost instantly as usual, but then stopped after about 8 seconds.

It fires up again with the starter, then stops again. It does this about 4 times before keeping running.

I don't think it is the fuel supply to the carb, but I think this is the most likely thing... the fuel level drops in the float chamber etc.

Why don't I think it is the fuel supply? Because the fuel pressure gauge shows nothing unusual ( the gauge take-off point is between the mechanical pump and the carby inlet ) and after the engine stays running, everything seems normal.

But what electrical thing could cause this problem?

As regards the choke, the stopping seemed not to be effected by choke or no choke.

Once in the air, everything was fine. Mind you, I have stayed close to the airfield after this event.

The 2.2 engine is now running on mogas, as it has for a couple of months now.

My 2200 hydraulic motor also starts instantly but if there was the slightest move with the throttle or choke it would stop.  If your idle is set a fraction too high using the mechanical stops then the motor may display stopping after starting. Try lowering the idle a little and keep the throttle hard closed for at least 30 seconds after starting and also don't touch the fully opened choke for the same period of time....

6 hours ago, New2flying said:

I started learning how to glide. I've done almost 20 flights now in a sailplane, they generally have a nose wheel, a wheel in the middle, and a tailwheel. How different is it for a pilot to land one of these aircraft to say a convention powered aircraft with or without a tailwheel?

In powered aircraft the throttle controls your rate of descent and the elevators control your airspeed.  In a glider the airbrakes control the rate of descent, elevators control airspeed. 

Instructors will normally teach students to arrive at base leg in an overshoot situation with airbrakes about half open.  On final the aiming point (not the touchdown point) is kept stationery on a point on the canopy using airbrakes. Airspeed is controlled using the elevators.  Your eyes remain on the aiming point until round out when you then look up to the far end of the strip.  Using peripheral vision you are then able to finely judge the landing and touchdown with the elevator.

In the early days of your training it is best to leave the airbrakes at a constant setting and concentrate completely on the landing. With more experience both the airbrakes and elevator are used almost simultaneously to achieve pinpoint landing precision.

Good luck with your glider training…I have always believed that anyone interested in learning to fly begin with gliding.  Back in the 70s and 80s there was some allowance made for gliding hours (5 hours I think) to be included in the PPL curriculum… a lot of my students, after transitioning to powered flying, would solo in less then 6 hours… many went on to aviation careers.

I have to qualify my previous comment.....every object on the surface of our planet is subject to 1 g so my estimation of a max of 2 g that the weight of the snow produced is inclusive of the gravitational acceleration constant.

10 hours ago, F10 said:

Seeing that Jab with all that snow on it.....wonder how many negative “g’s” it was pulling! Snow can be pretty heavy! I remember reading an article the Brit CAA wanted a builder to test to destruction, one complete built wing of a Fisher Flying Products Horison II, because despite Barnes Wallis and the brilliant Wellington, they didn’t believe the geodetic construction was acceptable. So, poor guy, he had to build a complete wing, mounted it inverted on a wall, and they started loading sandbags on it. When they got over 7g, it suffered a partial failure of the rear spar. The aircraft would never be able to fly fast enough, to get close to that kind of g loading.

The factory built ULD is rated at +8 -3.5 g.   I reckon the weight of snow would have applied <  - 1.5g maybe 2 g max.   Question.. why, in most aircraft, is the positive g limits greater then the negative g limits ?   

just adding my pennyworth.......a stall, spin or spiral dive characteristics in any aircraft today may be entirely different tomorrow....depending on aircraft loading / CG,  more fuel in one tank then the other and of course the currency of the pilot flying it.