Rans S21 Outbound build French Island. Nic and Mike. Start date 3rd May 2022. Finish date 1st February 2023. Target $ spend to be determined.

[Mike Gearon]

Update. Finally the hangar is nearly finished. Guess I’m proud of being 65 years old and doing 95% of it. Didn’t expect to be up and down ladders and screeding concrete at retirement age.

 

Temporarily moving the motor glider and S21 in. Motor glider has to go to Phil Organ north of Melbourne to get GFA certification for Australia. Can’t turn the motor off in RAA or CASA. I checked with RAA just to be sure. Can’t turn off. It’s a very involved process apparently to have it certified here. Will cost north of 10k. Loads of paperwork apparently and I thought of doing it but stopped at the word paperwork.

 

Temporary on the Rans because I still need to paint the floor. Nutech seems a good product. I’ve wet ground floor back so concrete pores are open. Just waiting for it to dry thoroughly. Resist8ng the temptation to get it painted.

 

Then back into Rans building aircraft 2.

 

Aircraft 1 is still waiting on the motor mount to come back from Florida. It’s been 3 months! We’ve had our ups a and downs with that UL engine. Shocked when the twin crashed in Florida. Now we have confirmation that the problem was in the electrical system. Each engine has 2 ECU’s. The backup still depends on getting power. Apparently during that critical takeoff period the voltage dropped dramatically for a number of reasons.

 

 

 

 

 

 

 

Edited March 15 by Mike Gearon
Images all black

[rodgerc]

Photos taken inside the hangar at night….No power connected to the hangar just yet. 

[RFguy]

Mike

On the UL electrical - I wonder how the dual ECU setup power is set up.

Given the issue and what you;'ve told me, it might be worthwhile to consider modifications / additional systems. 

 

a recent story...

I know a bit about the electricals of 915 rotax's these days.  I had to find/fix a charging intermittant. The Rotax has two alternators - A and B (ALT A, ALT B) 

A is rated about 15A, B at 30A. "A" normally runs the ECUs (all rotax electrical) (thru their 'fusebox/switchbox"), B is routed to the ship to run systems and charge the ship battery. .  In case of a failure of ALT A, the the system commenderes the B  ALT and the ship is cut loose to run on ship battery.

 

At start because there is no A or B, ship power is routed to the ECU C input until A(or B) gets going) then once running the ship power source is removed.

 

and I can confirm it all works well.  Everything including the dual injection fuel pumps are powered from the rotax control box, nothing can stop the rotax once it's going.... (except individual ECUs can be disabled- LANE A, LANE B) .  I've demonstrated removing the battery terminals while the prop was going  AND disconnected the output of ALT-A and it fails over onto ALT-B immediately cutting the ship lose.

 

[RFguy]

Mike I  gather the UL system  has one alternator and one ship battery.  usually the single alternator is doing double duty and I think that's a bad idea, since the engine systems are not isolated from the troubles and switches and breakers and ge-finger trouble of the user....  The only way to really get away from it is a 2nd power source., or perhaps an independent feed from the battery with its own isolation relay (or a 2nd battery only for the UL so that buys you an hour etc, and some switch that you can cut over the Ul to main ship battery- but then you have a single failure point in the cabin maybe....

so, some thought required to escape the single power feed issue. 

The UL systems having its own feed from the battery and own isolation switch etc is probably the simplist. 

[Mike Gearon]

4 hours ago, rodgerc said:

Photos taken inside the hangar at night….No power connected to the hangar just yet. 

That’s funny. I’ve asked admin why they won’t work. Uploaded from iPad as usual. No idea.

[Mike Gearon]

1 hour ago, RFguy said:

Mike I  gather the UL system  has one alternator and one ship battery.  usually the single alternator is doing double duty and I think that's a bad idea, since the engine systems are not isolated from the troubles and switches and breakers and ge-finger trouble of the user....  The only way to really get away from it is a 2nd power source., or perhaps an independent feed from the battery with its own isolation relay (or a 2nd battery only for the UL so that buys you an hour etc, and some switch that you can cut over the Ul to main ship battery- but then you have a single failure point in the cabin maybe....

so, some thought required to escape the single power feed issue. 

The UL systems having its own feed from the battery and own isolation switch etc is probably the simplist. 

I’ll mention this to Nic. He’s also an electronics guy so it’ll make sense to him,

[Mike Gearon]

Turned the hangar light on. 
Rv6 in behind the motorglider.

S21 towed from its old home.

[3rd harmonic]

17 hours ago, RFguy said:

Mike I  gather the UL system  has one alternator and one ship battery.  usually the single alternator is doing double duty and I think that's a bad idea, since the engine systems are not isolated from the troubles and switches and breakers and ge-finger trouble of the user....  The only way to really get away from it is a 2nd power source., or perhaps an independent feed from the battery with its own isolation relay (or a 2nd battery only for the UL so that buys you an hour etc, and some switch that you can cut over the Ul to main ship battery- but then you have a single failure point in the cabin maybe....

so, some thought required to escape the single power feed issue. 

The UL systems having its own feed from the battery and own isolation switch etc is probably the simplist. 

I have been thinking about my UL engine and I agree, RF guy this is likely the best approach.  The greatest danger with ECU's that need power for the engine to run is not the alternator failing as you will have some time to find somewhere to land - but a short to ground. I found that out the hard way with a 1980s BMW E30 323 coupe I used to own. Ill advisedly put a standard size battery in rather than the correct DIN66 battery, which wasn't quite as tall. This worked ok for abit until I went over a decent bump and the + battery post shorted out on the bonnet. The car stopped running instantly and I pulled off the road while fumbling for the bonnet released on the passenger side as the battery was fizzing out acid into the engine bay like crazy.

My thought was to have a smaller separate battery that ONLY feeds the ECU and have the isolated from the normal battery with a very heavy duty Schottky diode. Ordinarily the batteries will be charged in parallel, but a short on main bus won't take down the ECU and cause an immediate engine failure.

[facthunter]

I have a couple of Bendix magnetos for flat six Continental with shielded harness and impulse on one. Life once didn't have to be that complicated.   Nev

[3rd harmonic]

Yeah, look as good as points based magnetos for the time when they were the best thing available, life has moved on in the last 100 years. Solid state capacitor discharge ignitions are still simple enough, but miles better. Every lawnmower, small engine, motorcycle and of course the Rotax 91x series are a testament to that - even if carby is completely gummed up after years of non use generally you'll still get a spark that doesn't fail.

Having said that the 2hp 60yr old Briggs&Stratton points motor on my cement mixer hasn't failed yet even though it lives outside with a bag over it...

[facthunter]

There's no difference between a spark from a magneto or another source . Modern stuff is a testament to hard to diagnose faults and more dependency on power sources. Magnetos are INDEPENDENT of  everything. Latest isn't always BEST. It can be just what you are forced to have.. because other options are not available.  The market moves on to not field repairable so they have you by the balls. Nev

[RFguy]

take a good look at the fuel injection pump current requirements under various condix, they can pull a fair bit, and that you might have BOTH pumps on due to design (or error ?) 

Given that good quality, sealed non liquid electrolyte batteries generally do not have sudden failures, it's probably a good option as a power source.  a strong schottky diode or MOSFET schottky implementation with some sort of current limit would be a simple and reliable option.  A big schottky with say only 20V 30V reverse barrier will be pretty low voltage drop.  maybe something like 12 or 14 gauge wire will serve as a current limit....maybe aim for wire resistance = diode drop under normal conditions, as a starting point. that will be fine as long as the charging system gets up to 14.4 , 14.6V region

[Thruster88]

Pilots need to know and understand the systems with engines that operate with ECU. 

 

Accident ignites DA42 engine row | News | Flight Global

WWW.FLIGHTGLOBAL.COM

 

[facthunter]

A charged Battery  is an essential feature of a modern aeroplane's airworthiness. That's where we are at.  Nev

[RFguy]

The FI rotax does not begin to charge the battery until 7 seconds or so over 2500 RPM.

So after oil pressure is established, need to get RPM up to 2550 etc so the battery starts charging, this is obvious by looking at the ship battery voltage.

Until that time, the ship battery  is in discharge for internal ship loads (and not yet being charged by ALT-B) 

The ALT-A begins to run the ECU at about 1200-1300 RPM, approx. Very low RPM in flight (how ?) might cause some ECU confusion and require ECU to be powered by the ship battery if RPM too low to run the system from ALT-A/B

 

Just discussing the rotax here because it's a good example of how it can be done.  Putting aside miscellaneous annoyances and sensor issues of the FI rotax.

Edited March 17 by RFguy

[BurnieM]

On a 912IS;

connect engine to battery (startup/backup power switch)

start engine

startup power off

once rotating alt B (30A) powers engine (ecu, fuel pumps etc)

increase revs to 2500 for 6 sec and engine switches to alt A (16A)

Alt B is now available to charge battery

So you know you have 2 good alternators and battery is charging before you leave the ground.

 

I believe Rotax reconmends a 1400rpm idle speed

Edited March 17 by BurnieM

[Blueadventures]

10 minutes ago, BurnieM said:

On a 912IS;

connect engine to battery (startup/backup power switch)

start engine

startup power off

once rotating alt B (30A) powers engine (ecu, fuel pumps etc)

increase revs to 2500 for 6 sec and engine switches to alt A (16A)

Alt B is now available to charge battery

So you know you have 2 good alternators and battery is charging before you leave the ground.

 

I believe Rotax reconmends a 1400rpm idle speed

This is a good example of detail in aircraft check lists so we get things correct.  The preferred idle speed will first be used after start. (eg say 2,200 /2,300 where engine smoothest for a short period then say 2,500 to warm up, etc).  Add a flat battery start procedure as well.

[BurnieM]

Clarify idle speed;

1400 is with zero throttle

 

Normally we use 2000 for warm up

[RFguy]

10 minutes ago, BurnieM said:

On a 912IS;

connect engine to battery (startup/backup power switch)

start engine

startup power off

once rotating alt B (30A) powers engine (ecu, fuel pumps etc)

increase revs to 2500 for 6 sec and engine switches to alt A (16A)

Alt B is now available to charge battery

So you know you have 2 good alternators and battery is charging before you leave the ground.

I believe Rotax reconmends a 1400rpm idle speed

Advice on idle : (documentation : ROTAX OM915, 912
"Section 2.1 " 

engine start : 
for iS engines -Section  "3.4) After engine start"
"Set linearized throttle position in a way that the engine runs at approx. 2000 rpm for approx. 2 minutes."

then

"Set linearized throttle position in a way that the engine runs at approx. 2500 rpm until oil temperature reaches 50 °C (120 ° F)." 

If you run a 912ULS at 1400rpm you'll foul up the plugs because the mixture between front and rear cylinders goes wild. (one end goes rich - front ? cant remember) .

 

 

 

[Blueadventures]

4 minutes ago, RFguy said:

Advice on idle : (documentation : ROTAX OM915, 912
"Section 2.1 " 

engine start : 
for iS engines -Section  "3.4) After engine start"
"Set linearized throttle position in a way that the engine runs at approx. 2000 rpm for approx. 2 minutes."

then

"Set linearized throttle position in a way that the engine runs at approx. 2500 rpm until oil temperature reaches 50 °C (120 ° F)." 

If you run a 912ULS at 1400rpm you'll foul up the plugs because the mixture between front and rear cylinders goes wild. (one end goes rich - front ? cant remember) .

 

 

 

With ULS there is info that rpm after start best at 2,200 or towards 2,300 where engine is smoothest as this is better for the gear box. Low rpm idles hurts the gear box internals.

[facthunter]

Attention demanding little gizmo's aren't they?   Nev

[RFguy]

5800 is normal TO max.

anyway, enough, we are polluting Mike's thread.
No more rotax talk

[facthunter]

 Mike is past his project's finish date. Special conditions apply. .  Nev

[facthunter]

Well, WHO ever finished a project on time? Especially something to do with Aeroplanes.  Nev

[Mike Gearon]

I’m fine with the thread wandering. Not a subscriber to strict rules. To quote my brother “mikes not very good with rules”

That is unless we are talking aviation…. I’m very good with the rules! Flew into Moorabin for the first time this morning for transponder install in the RV6. All went to plan after good YouTube videos on procedure. Gov documentation is shamefully useless for pilots new to the YMMB Cluster F%!# 

 

 

On topic……..I met Nic for coffee this morning and this thread/ discussion stimulated our discussion on ECU’s and bus bars. I think we will have seconds of both on the UL aircraft. 
 

Note on the UL failure un Florida (twin)  The battery voltage was quite low from starting and it was retracting the gear that pulled the voltage below what the ECU’s would accept.

 

discussion also had me looking up my Continental light speeds. I thought these suckers didn’t need external power. They do. Interesting they ship with the Schotty diode mentioned in this thread.

 

What are the power requirements for the Plasma CD systems?

•  The current versions of Plasma CDI systems need a minimum of 6.2 volts to start operation.  This is more than 2 volts less than the minimum voltage needed by the starter solenoid, thereby eliminating the possibility of kick-backs during starter operation.
  
  Plasma systems shipped before December 20 of 2004, need 8.5 volts to start operation.  This higher "on" voltage can cause a misfire if the starter current drain is high and/or the battery is weak and the voltage collapses below this threshold during cranking.  Systems shipped before 2005, can be upgraded to have the lower voltage capability.  
  
  Once the engine is running, all systems operate down to less than 5 volts, should you lose your charging system.

7.) Back-up battery?

• All Dual systems are shipped with a Schottky diode to be used with a back-up battery.  A simple wiring diagram is also supplied.

Any aircraft with a starter has excess energy stored in the battery for starting.  In flight, this large capacity is not needed.  In case of an alternator failure, 17ah or more should be available.  If this is only used for the ignition (2ah at 13.8v), the airplane will probably run out of fuel before the battery does.  It should be standard procedure to land ASAP if there is a charging problem on an all-electric plane.  Also, one of the Plasma systems can be switched off to minimize current consumption since the power is nearly the same, especially when the interconnect feature is used.