View Full Version : Ventus CM starting problems
For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?
SoaringXCellence
July 13th 20, 04:09 AM
Lucas,
When was the last time the power cables to the starter were replaced? Sometimes the cables start to have strands break inside the insulation due to flexing and vibration. This reduces the effective cross-section and increases the resistance.
Have you checked the cable fittings where they attach to the solenoid and the starter? If they are loose it can lead to arcing and overheating, again increasing resistance. If they are corroded they may not make good contact with the bolts where they mount to the starter or relay.
That's where I would start looking.
Mike Bamberg
El lunes, 13 de julio de 2020, 0:09:49 (UTC-3), SoaringXCellence escribió:
> Lucas,
>
> When was the last time the power cables to the starter were replaced? Sometimes the cables start to have strands break inside the insulation due to flexing and vibration. This reduces the effective cross-section and increases the resistance.
>
> Have you checked the cable fittings where they attach to the solenoid and the starter? If they are loose it can lead to arcing and overheating, again increasing resistance. If they are corroded they may not make good contact with the bolts where they mount to the starter or relay.
>
> That's where I would start looking.
>
> Mike Bamberg
Hi Mike! Thanks for your response. I´ve never changed the cables. I own the Ventus CM since 2017, don´t know if they were replaced before that (it was built in 1991)
What I am doing now is installing adicional cables, so I will duplicate the section. Te first test I did, I recover 1.5volt measured on the starter, so now, instead of 6volts, I have 7.5 volts on the starter. It seems to run faster... But I would like to know if this drop of voltage is normal or the problem is only mine.
Dave Nadler
July 13th 20, 11:37 PM
On Sunday, July 12, 2020 at 6:13:50 PM UTC-4, wrote:
> ...I have a voltage lost of aprox 2 volts over the positive wire
> and 1.5 over the negative one.
That's a ENORMOUS voltage drop!
I never owned one of these beasts, but...
1) If you let it crank (or try) for a brief period,
the area dropping the voltage will heat up.
First expose as many as possible cables, connection points,
and relays. Then crank for a bit, and feel for hot spots.
You might be able to find problem areas quickly this way...
2) This beast is a kinda old. You've got most likely got bad
connections, maybe starter relay, and possibly cables.
Connection points corrode over time, especially if the beast
has lived in humid climates. Consider undoing, cleaning,
and reattaching ALL connection points.
3) You're absolutely on the right path looking for drops,
and obviously you see there's a horrible problem on both
high and 'ground' sides...
Hope that helps, and let us know what you find!
Best Regards, Dave
On Sunday, July 12, 2020 at 3:13:50 PM UTC-7, wrote:
> For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?
The inrush current demand of a starter can be as much as 150 amp. Obviously, any resistance in the circuit (and I do mean any) will result in a substantial voltage drop, but not 3 - 3.5 V. You have a corroded connection somewhere. Replacing the cables WILL NOT solve the problem (unless they are damaged). You must find the bad connection(s). Taking everything apart and polishing them down to bright metal is the solution.
Your battery is bad and needs to be replaced (no surprise there). Typically they have 10 milliohms of internal resistance which means a 1 V drop at 100 amp. Any more means the internal resistance has gone up to the "toss it" level.
Tom
Tango Whisky
July 14th 20, 06:08 AM
The Ventus cm starter pulls 50 amps max. If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.
>If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.
True, but the relay might have two functions. One described is about physically moving the gear to engage the flywheel. The other function is to connect the starter to the battery. It could be wimpy at the second but still ok at the first.
Divide and conquer is a great plan for finding this. You already started measuring the + and - paths separately. Maybe look in more detail. Can you measure to the wire in the middle to figure if a particular connection or the relay is most of the drop. Assuming the bolted connections are clean and tight, that leaves the crimps where the wire ends are connected to the lugs, the starter relay internals, and the wire itself where it flexes going up and down. Maybe the voltmeter can isolate further.
Good luck.
kinsell
July 14th 20, 01:53 PM
On 7/12/20 4:13 PM, wrote:
> For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?
>
You might also try using a clamp-on ammeter to check for excessive
current draw. Not out of the realm of possibility that shorted windings
on the starter motor are causing unusually high current, which would
lead to large drops on the cables and at the battery.
On Tuesday, July 14, 2020 at 12:11:22 AM UTC-4, 2G wrote:
> On Sunday, July 12, 2020 at 3:13:50 PM UTC-7, wrote:
> > For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?
>
> The inrush current demand of a starter can be as much as 150 amp. Obviously, any resistance in the circuit (and I do mean any) will result in a substantial voltage drop, but not 3 - 3.5 V. You have a corroded connection somewhere. Replacing the cables WILL NOT solve the problem (unless they are damaged). You must find the bad connection(s). Taking everything apart and polishing them down to bright metal is the solution.
>
> Your battery is bad and needs to be replaced (no surprise there). Typically they have 10 milliohms of internal resistance which means a 1 V drop at 100 amp. Any more means the internal resistance has gone up to the "toss it" level.
>
> Tom
You can get a relatively inexpensive IR camera for your smart phone and take a look at the whole system while starting. Bad connections will show up quickly as hot-spots. Great trouble shooting tool.
Uli
'AS'
El martes, 14 de julio de 2020, 10:04:48 (UTC-3), AS escribió:
> On Tuesday, July 14, 2020 at 12:11:22 AM UTC-4, 2G wrote:
> > On Sunday, July 12, 2020 at 3:13:50 PM UTC-7, wrote:
> > > For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?
> >
> > The inrush current demand of a starter can be as much as 150 amp. Obviously, any resistance in the circuit (and I do mean any) will result in a substantial voltage drop, but not 3 - 3.5 V. You have a corroded connection somewhere. Replacing the cables WILL NOT solve the problem (unless they are damaged). You must find the bad connection(s). Taking everything apart and polishing them down to bright metal is the solution.
> >
> > Your battery is bad and needs to be replaced (no surprise there). Typically they have 10 milliohms of internal resistance which means a 1 V drop at 100 amp. Any more means the internal resistance has gone up to the "toss it" level.
> >
> > Tom
>
> You can get a relatively inexpensive IR camera for your smart phone and take a look at the whole system while starting. Bad connections will show up quickly as hot-spots. Great trouble shooting tool.
>
> Uli
> 'AS'
Thank you all for all the answers and advises.
I´ll try to reasume all the thing I´ve done on my glider.
This glider belonged originally to David Noyes (NL) in USA.
I bought it in 2017 to its 3rd owner C. Collman and imported to Argentina.
Since then, it started regularly but always with very few power, giving me doubts if i had to restart while flying to fly back home. Fortunately, it started all the times I really needed. (no more than 6)
I made a service to the original electric starter and it improved a little.
After one and a half year, dec 2018, first thing I replaced was Battery. I bought an Odyssey PC680, 12V 16Amp... but the problem was not yet solved.
Last year I decided to bought a new starter (the same as original), new relay (the same as original) and new coils and of course new spark plugs, and sparkplugs cables, etc etc.
I changed everything while applying an AD (propeller bearing replace) last year, and during last summer it seemed to be doing well.(we also found other problems that were repaired)
Now, after quarantine, I noticed the starter was running slow again and I began to inspect the electric installation.
This glider`s electric system is very simple: The positive wire goes from the battery directly to a 50Amp masterswitch/fuse. Then goes directly to the relay and then to the starter. The negative wire goes directly from battery to the engine pylon where starter is screwed.
The drops of voltage are (divided by section):
0-On battery: 3V. !! (measuring battery poles) (no voltage drops on connector)
1-from battery to fuse: 0.3V.
2-on the fuse: 0.22V.
3-from fuse to relay: 0.85V
4-on the relay: 0.2V
5-from relay to starter: 0.55V
Total drop on positive wire: 2.12V (the drops on the wire are proportional to the lenght of each section of wire) (total lenght of wires is more than 5 meters)
Total drop on negative wire: 1.4V
Total drop of voltage: 3.5V + 3V (battery) = 6.5V. Voltage on starter is 6.2 when battery is 12.7 !!
Tests done duplicating wires improves 1.4 volt on the starter. All the contacts are in good condition and clean.
So, the battery is a very good one (at least that is what the seller told me and what i could investigate myself) and is 1.5 years old, used for no more than 100/120 starts (including all the test I did).
The relay is new. The starter is new….( Less use than the battery)
I can't find a certain place where there are point voltage drops. I'm totally lost. I don´t want to buy a new battery and find that wasn´t the problem.
Next to do, I will measure the current with a DC Amperimeter in order to check if starter is consuming more tan normal.. It is labeled 400W, so it should consume no more than 35 Amp. And I will try to get borrowed another battery to compare.
One thing to make clear: once the engine starts it runs perfectly with any problem. Never stopped itself. No carburation problems.
But i am thinking now:… Could the engine be hard? Heavy? Even if i decompress it to start spinning
Regards,
Lucas
Eric Greenwell[_4_]
July 14th 20, 10:49 PM
wrote on 7/14/2020 1:41 PM:
> El martes, 14 de julio de 2020, 10:04:48 (UTC-3), AS escribió:
>> On Tuesday, July 14, 2020 at 12:11:22 AM UTC-4, 2G wrote:
>>> On Sunday, July 12, 2020 at 3:13:50 PM UTC-7, wrote:
>>>> For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What ...
> Next to do, I will measure the current with a DC Amperimeter in order to check if starter is consuming more tan normal.. It is labeled 400W, so it should consume no more than 35 Amp. And I will try to get borrowed another battery to compare.
>
> One thing to make clear: once the engine starts it runs perfectly with any problem. Never stopped itself. No carburation problems.
>
> But i am thinking now:… Could the engine be hard? Heavy? Even if i decompress it to start spinning
>
> Regards,
> Lucas
What is gauge of the wires from the battery to the starter? I'd suggest at least 8
gauge if the starter draw is 50 amps; 6 gauge if it's 100 amps.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1
El martes, 14 de julio de 2020, 18:49:39 (UTC-3), Eric Greenwell escribió:
> wrote on 7/14/2020 1:41 PM:
> > El martes, 14 de julio de 2020, 10:04:48 (UTC-3), AS escribió:
> >> On Tuesday, July 14, 2020 at 12:11:22 AM UTC-4, 2G wrote:
> >>> On Sunday, July 12, 2020 at 3:13:50 PM UTC-7, wrote:
> >>>> For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What ...
> > Next to do, I will measure the current with a DC Amperimeter in order to check if starter is consuming more tan normal.. It is labeled 400W, so it should consume no more than 35 Amp. And I will try to get borrowed another battery to compare.
> >
> > One thing to make clear: once the engine starts it runs perfectly with any problem. Never stopped itself. No carburation problems.
> >
> > But i am thinking now:… Could the engine be hard? Heavy? Even if i decompress it to start spinning
> >
> > Regards,
> > Lucas
>
> What is gauge of the wires from the battery to the starter? I'd suggest at least 8
> gauge if the starter draw is 50 amps; 6 gauge if it's 100 amps.
>
>
> --
> Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
> - "A Guide to Self-Launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1
Original wires are AWG8 (8,3mm2) Now I am installing an additional 10mm2 wire to try and test, so I will have 18mm2
Lucas,
I have separate cables that allow me to start the engine using my car's battery without the glider's battery. If you have that, try it and determine if the battery is good or not.
If you don't have that cable-try VERY CAREFULY to apply 12V from your car battery directly to the starter. takes 2 people-one in the cockpit one near the car battery. This to determine if the starter is OK or not.
Be careful !
Dan
On Tuesday, July 14, 2020 at 4:41:58 PM UTC-4, wrote:
> El martes, 14 de julio de 2020, 10:04:48 (UTC-3), AS escribió:
> > On Tuesday, July 14, 2020 at 12:11:22 AM UTC-4, 2G wrote:
> > > On Sunday, July 12, 2020 at 3:13:50 PM UTC-7, wrote:
> > > > For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?
> > >
> > > The inrush current demand of a starter can be as much as 150 amp. Obviously, any resistance in the circuit (and I do mean any) will result in a substantial voltage drop, but not 3 - 3.5 V. You have a corroded connection somewhere. Replacing the cables WILL NOT solve the problem (unless they are damaged). You must find the bad connection(s). Taking everything apart and polishing them down to bright metal is the solution.
> > >
> > > Your battery is bad and needs to be replaced (no surprise there). Typically they have 10 milliohms of internal resistance which means a 1 V drop at 100 amp. Any more means the internal resistance has gone up to the "toss it" level.
> > >
> > > Tom
> >
> > You can get a relatively inexpensive IR camera for your smart phone and take a look at the whole system while starting. Bad connections will show up quickly as hot-spots. Great trouble shooting tool.
> >
> > Uli
> > 'AS'
>
> Thank you all for all the answers and advises.
> I´ll try to reasume all the thing I´ve done on my glider.
> This glider belonged originally to David Noyes (NL) in USA.
> I bought it in 2017 to its 3rd owner C. Collman and imported to Argentina..
> Since then, it started regularly but always with very few power, giving me doubts if i had to restart while flying to fly back home. Fortunately, it started all the times I really needed. (no more than 6)
> I made a service to the original electric starter and it improved a little.
> After one and a half year, dec 2018, first thing I replaced was Battery. I bought an Odyssey PC680, 12V 16Amp... but the problem was not yet solved.
> Last year I decided to bought a new starter (the same as original), new relay (the same as original) and new coils and of course new spark plugs, and sparkplugs cables, etc etc.
> I changed everything while applying an AD (propeller bearing replace) last year, and during last summer it seemed to be doing well.(we also found other problems that were repaired)
> Now, after quarantine, I noticed the starter was running slow again and I began to inspect the electric installation.
> This glider`s electric system is very simple: The positive wire goes from the battery directly to a 50Amp masterswitch/fuse. Then goes directly to the relay and then to the starter. The negative wire goes directly from battery to the engine pylon where starter is screwed.
> The drops of voltage are (divided by section):
> 0-On battery: 3V. !! (measuring battery poles) (no voltage drops on connector)
> 1-from battery to fuse: 0.3V.
> 2-on the fuse: 0.22V.
> 3-from fuse to relay: 0.85V
> 4-on the relay: 0.2V
> 5-from relay to starter: 0.55V
> Total drop on positive wire: 2.12V (the drops on the wire are proportional to the lenght of each section of wire) (total lenght of wires is more than 5 meters)
> Total drop on negative wire: 1.4V
> Total drop of voltage: 3.5V + 3V (battery) = 6.5V. Voltage on starter is 6.2 when battery is 12.7 !!
> Tests done duplicating wires improves 1.4 volt on the starter. All the contacts are in good condition and clean.
>
> So, the battery is a very good one (at least that is what the seller told me and what i could investigate myself) and is 1.5 years old, used for no more than 100/120 starts (including all the test I did).
> The relay is new. The starter is new….( Less use than the battery)
> I can't find a certain place where there are point voltage drops. I'm totally lost. I don´t want to buy a new battery and find that wasn´t the problem.
>
> Next to do, I will measure the current with a DC Amperimeter in order to check if starter is consuming more tan normal.. It is labeled 400W, so it should consume no more than 35 Amp. And I will try to get borrowed another battery to compare.
>
> One thing to make clear: once the engine starts it runs perfectly with any problem. Never stopped itself. No carburation problems.
>
> But i am thinking now:… Could the engine be hard? Heavy? Even if i decompress it to start spinning
>
> Regards,
> Lucas
Dan, many times I connected car battery to glider battery with car battery emergency wires and the difference is very big. The starter "flies" and the engine starts very easily. I will try directly to the starter as you say. Thank you!
It will be interesting to see the starter terminal amps and volts as is and with a car battery beefing up the glider battery.
> The drops of voltage are (divided by section):
relay and fuse .42 (.22+.2)
wires 1.4 and 1.7 (.3+.85+.55)
Willie Sutton robbed banks because that's where the money was.
The bulk of volts are in the wires, so maybe more divide and conquer there?
Is there a way to separate the wire drop from the lugs on the end of the wires? (Maybe stick a needle probe into the wire just past the crimp.)
Lucas,
Try also to use only a car battery, without the glider battery.
Disconnect the wires from the glider battery and connect the wires to the car battery using the emergency cables.
See what happens.
Dan
On Tuesday, July 14, 2020 at 7:11:34 PM UTC-4, wrote:
> Dan, many times I connected car battery to glider battery with car battery emergency wires and the difference is very big. The starter "flies" and the engine starts very easily. I will try directly to the starter as you say. Thank you!
El domingo, 12 de julio de 2020, 19:13:50 (UTC-3), escribió:
> For those who own Ventus Cm: have you ever measured the voltage on the starter when it is running?. Mine, with fully charged battery, while electric starter is running, voltage on battery fall out to 10volts, and on starter I measured only 6 or 6.5 volts. I have a voltage lost of aprox 2 volts over the positive wire and 1.5 over the negative one. Is that normal? I have starting troubles sometimes and i think it is because of it. What can you tell me about it?
Ok, Thank you all for your replies and advises again. I´ve made all kind of measurements. No bad connections, no bad relay, no bad battery and starter is brand new. NO hot spots, no weaks connections.
I disconnected everything and check all the contacts and terminals. It seems the drop of voltage was mainly on the wires due to its length and age. I finally installed a second complementary 10mm2 wire all the way from battery to starter and back with negative wire. (it is impossible to remove the original wires without having to dismantle all the glider)
Now, when cranking, battery voltage drops from 12.7 to 10.5 but on starter terminals I measured 7.5 Volts. With this, the starter runs to much faster and the engine starts as easy as when I supplied energy from the car with the car emergency wires. Never, since I have this glider, it cranked as fast and started as easily.
Anyway, if someday someone has the opportunity to measure the voltage on the battery and on the starter while cranking, please let me know. I really would like to compare my glider with someone´s else. THANK YOU very much.
On Monday, July 13, 2020 at 10:08:36 PM UTC-7, Tango Whisky wrote:
> The Ventus cm starter pulls 50 amps max. If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.
If you are not using a scope and a current shunt to measure inrush current you will never see the peak current, and it is the peak current that the starter electrical system must deliver to get the starter rotating and generating its back EMF that reduces the current.
Tom
Dave Nadler
July 21st 20, 12:57 AM
On Monday, July 20, 2020 at 6:34:42 PM UTC-4, 2G wrote:
> On Monday, July 13, 2020 at 10:08:36 PM UTC-7, Tango Whisky wrote:
> > The Ventus cm starter pulls 50 amps max. If the starter relay is bad (not the connections), the starter will spin without engaging into the starter wheel.
>
> If you are not using a scope and a current shunt to measure inrush current you will never see the peak current, and it is the peak current that the starter electrical system must deliver to get the starter rotating and generating its back EMF that reduces the current.
>
> Tom
Right, I expect that 50 amps is the steady-state cranking current,
and the initial current to be MUCH larger. Diagnosing a problem with
a much smaller motor I measured 130A peak for some 10s of msec.
As Tom says, you need a scope and current clamp to really see the detail.
Hope that helps!
Best Regards, Dave
Dave Nadler
July 21st 20, 12:58 AM
On Monday, July 20, 2020 at 3:54:04 PM UTC-4, wrote:
> Now, when cranking, battery voltage drops from 12.7 to 10.5
> but on starter terminals I measured 7.5 Volts.
Lucas, 3v is still a pretty huge drop!
Keep looking!
> Now, when cranking, battery voltage drops from 12.7 to 10.5 but on starter terminals I measured 7.5 Volts. With this, the starter runs to much faster and the engine starts as easy as when I supplied energy from the car with the car emergency wires. Never, since I have this glider, it cranked as fast and started as easily.
Maybe quit and declare success.
Or add more, nore copper.
Or measure the steady state amps to go with the similar volts and see if the loss in the wires are as expected.
The electrical parts might be working as designed and there is an extra mechanical load?
Dave Nadler
July 21st 20, 02:09 AM
On Monday, July 20, 2020 at 7:58:24 PM UTC-4, Dave Nadler wrote:
> On Monday, July 20, 2020 at 3:54:04 PM UTC-4, wrote:
> > Now, when cranking, battery voltage drops from 12.7 to 10.5
> > but on starter terminals I measured 7.5 Volts.
>
> Lucas, 3v is still a pretty huge drop!
> Keep looking!
OTH, if its really 50A steady state (at 7.5v that's .5hp!),
3V = 50A * .06 ohm
So system resistance is not crazy...
danlj
July 22nd 20, 04:36 AM
I've owned a Ventus CM for 20 years, have taken the engine from 17 hours to 67 hours and the airframe to 1200 hours without any starting difficulties. I have nothing to add to the preceding comments, and have no debate with them. I only wish to add my own experience.
As someone once said, all an engine needs is air, fuel, and spark -- in the right amounts. Here are some of the things I've learned:
1: Having the spark plug gapped correctly is critical to reliability -- 0.5mm -- I have used platinum plugs with complete satisfaction.
2: Having a charged battery -- 12.8 volts or more seems optimal.
3: Obvious but essential:
Fuel valve OPEN
Boost pump ON
Proper carburetor prime: too little and the engine won't start; too much and the plugs flood, and must be removed and cleaned because they're at the bottom of the cylinders. When the engine is cold, especially in cool weather, in my ship 4 full squeezes of the priming bulb is the minimum. If the engine doesn't start promptly, an extra squeeze or two while it's cranking may help.
In-air starts require less prime, probably because the engine retains some warmth in the engine bay.
4: As hinted by this thread, and taught to me, the #1 cause of electrical malfunction is *corroded contacts*. It is possible to check the resistance across contacts -- or simply disconnect, freshen the metal, reconnect, and spray with anticorrosion lube.
5: In-air shutdown: The manual says to let the engine cool at idle before stopping and stowing it. Years ago, I spoke to the engine designer, Wolfgang Emmerich, about this. He was *adamant* that this not be done. "I owned one of those gliders; I don't know why manufacturers give this advice. If you do not shut it down at full throttle, the carbs are over-pressured and they begin to leak."
I'd had some leakage at that point; I've ever since shut down at full power, and the leakage has never worsened, just a couple of drops.
6: I forgot to mention: both the starter button and the radio microphone button are on the stick. If one doesn't look, it is possible to be pressing the microphone button on final to the off-field landing. This has been done by at least two pilots, to my knowledge. The engine only starts if the started button is pressed... ;-)
El miércoles, 22 de julio de 2020, 0:36:05 (UTC-3), danlj escribió:
> I've owned a Ventus CM for 20 years, have taken the engine from 17 hours to 67 hours and the airframe to 1200 hours without any starting difficulties. I have nothing to add to the preceding comments, and have no debate with them. I only wish to add my own experience.
> As someone once said, all an engine needs is air, fuel, and spark -- in the right amounts. Here are some of the things I've learned:
> 1: Having the spark plug gapped correctly is critical to reliability -- 0..5mm -- I have used platinum plugs with complete satisfaction.
> 2: Having a charged battery -- 12.8 volts or more seems optimal.
> 3: Obvious but essential:
> Fuel valve OPEN
> Boost pump ON
> Proper carburetor prime: too little and the engine won't start; too much and the plugs flood, and must be removed and cleaned because they're at the bottom of the cylinders. When the engine is cold, especially in cool weather, in my ship 4 full squeezes of the priming bulb is the minimum. If the engine doesn't start promptly, an extra squeeze or two while it's cranking may help.
> In-air starts require less prime, probably because the engine retains some warmth in the engine bay.
> 4: As hinted by this thread, and taught to me, the #1 cause of electrical malfunction is *corroded contacts*. It is possible to check the resistance across contacts -- or simply disconnect, freshen the metal, reconnect, and spray with anticorrosion lube.
> 5: In-air shutdown: The manual says to let the engine cool at idle before stopping and stowing it. Years ago, I spoke to the engine designer, Wolfgang Emmerich, about this. He was *adamant* that this not be done. "I owned one of those gliders; I don't know why manufacturers give this advice. If you do not shut it down at full throttle, the carbs are over-pressured and they begin to leak."
> I'd had some leakage at that point; I've ever since shut down at full power, and the leakage has never worsened, just a couple of drops.
> 6: I forgot to mention: both the starter button and the radio microphone button are on the stick. If one doesn't look, it is possible to be pressing the microphone button on final to the off-field landing. This has been done by at least two pilots, to my knowledge. The engine only starts if the started button is pressed... ;-)
Thank you Danlj.
Throughout these last three years that I own my ship, I´ve learned a lot about this engine...I had plugs flooded sometimes also. I heard before about stopping the engine at full power, but never with that conviction.
After stopping it did you used to wait to cool for a while or you stowed it directly?
I also heard about pressing the wrong button to start the engine!! but mine has the PTT button not at the top of the stick but in its front, so, no mistake there.
I would like to ask you a question also. These mikuni BN 38 carburators has needle valve seat (pop off) sized 2.0. There are pop off of 1.5 and 2.5 also. The standard carburator parts drawing indicates 1.5 for Mikuni BN 38, do you remember what is the indicated one for this engine? Anyway, mine with 2.0 works ok, but I still have this doubt.
Regards.
Well.... some PC680 batteries appear to not be the same quality they were in the past. Alot of homebuilt aircraft use them an owners are complaining about the poor service life compared to what they were in the past.
If you can try someone elses battery or try your battery in a similar glider as see how it goes.
There are some devices around that can test the performance of a starter battery in cars. They measure the CCA potential of the battery in a few seconds, perhaps a local auto electrican can do this for you. It only takes a few seconds to do.
Brett
On Saturday, July 25, 2020 at 3:56:07 AM UTC-7, wrote:
> Well.... some PC680 batteries appear to not be the same quality they were in the past. Alot of homebuilt aircraft use them an owners are complaining about the poor service life compared to what they were in the past.
>
> If you can try someone elses battery or try your battery in a similar glider as see how it goes.
>
> There are some devices around that can test the performance of a starter battery in cars. They measure the CCA potential of the battery in a few seconds, perhaps a local auto electrican can do this for you. It only takes a few seconds to do.
>
> Brett
Google "cca tester" and you will find a bunch that are under $50.
Tom
Dave Nadler
July 28th 20, 01:52 AM
On Monday, July 20, 2020 at 9:09:52 PM UTC-4, Dave Nadler wrote:
> On Monday, July 20, 2020 at 7:58:24 PM UTC-4, Dave Nadler wrote:
> OTH, if its really 50A steady state (at 7.5v that's .5hp!),
> 3V = 50A * .06 ohm
> So system resistance is not crazy...
Something still not right Lucas.
From your wire 18 mm2 of length 2x 5m, your cables should have ~ .01 ohm total.
And its most likely less than 50A steady-state cranking, so you've
actually got closer to .1 ohm.
Matters a lot at these current levels!
Hmmm...
El lunes, 27 de julio de 2020, 21:52:31 (UTC-3), Dave Nadler escribió:
> On Monday, July 20, 2020 at 9:09:52 PM UTC-4, Dave Nadler wrote:
> > On Monday, July 20, 2020 at 7:58:24 PM UTC-4, Dave Nadler wrote:
> > OTH, if its really 50A steady state (at 7.5v that's .5hp!),
> > 3V = 50A * .06 ohm
> > So system resistance is not crazy...
>
> Something still not right Lucas.
> From your wire 18 mm2 of length 2x 5m, your cables should have ~ .01 ohm total.
> And its most likely less than 50A steady-state cranking, so you've
> actually got closer to .1 ohm.
> Matters a lot at these current levels!
> Hmmm...
Yes, I know something is still not right.... but I can´t find what! I´ll continue searching and let you know. Thank you
What was the actual current?
vBulletin® v3.6.4, Copyright ©2000-2025, Jelsoft Enterprises Ltd.