Pull Up Now!

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You're using BP gas? Well, NOWONDER bad performance. There's probably salt water mixed in.

AE25

water injection for added power on takeoff? (FAIL)

just read alot of this thread.
interested to see what you guys think of converting a 4stroke .61 10cc to gas?
is there a walbro small enough to suit? or any other options for carb?
is the added weight of ignition etc too much for the power output of a 10cc gasser in a plane?
thanks in advance

Pull Up Now!

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You have to want to run gas as opposed to nitro, because the same size engine will not produce as much power. Even though nitro fuel heat caloric content is lower, it is being run much richer because it's naturally oxygenated (as opposed to gasoline). So in a finite amount of equal time, the engine on nitro will process far more fuel and as such produce more power.

And yes, then there's the added battery & ignition weight. I've often thought that the battery could be dealt with by using a small lipo possibly with a small regulator, or a lightweight ESC. As for the ignition, there is a great need in this hobby for someone to develop a light weight ignition box. Much of the weight is the housing and the potting compound they fill the box with. I assume they are doing that for vibration, though I'm not sure why. Our servos and receivers survive, after all. It could be the combination of the high voltage and coil that causes insulation resistance breakdown under vibration.

CH Ignitions

My Feedback: (11)

They do that to prevent people of reverse eng. and stole the idea. I start to do my own cdi with the help of this forum.
The bad part is that HV transformer is hevy. For a 10cc ,only add ignition, a radio, battery, wheels and you are done, no more framework. For a Car/Boat i guess will be fine. As a carb I think u can use the stock . What you guys are thinking?
For more fun I will try one just for the kack of it. Put a magnet, sensor and try to see.

Adrian
I may ad some solt also from my BP gas

Ed Vollmer

My Feedback: (14)

I think it is foolish to fill the ignition box with all that potting compound. It adds a tremendous amount of weight to an item that is should be very weight conscious. That amount of potting certainly is not needed for component protection and adds nothing to mitigate RF.

As far as keeping the circuit secret; it is a fairly direct copy of CH Ignitions circuit which is, in turn, a copy of an automotive design from the 1970s. The timing module is still kept separate from the main board and is similar to the CHI Syncro Spark timing module. If the design were original the timing element would be incorporated into the main board and save money, weight, and complexity.

Having said all that, I own a half dozen RCEXL ignitions myself and have installed many dozens more. They are a good ignition and perform the task well. Other brands, not so much.

Just my 2 cents.

Ed V.

CH Ignitions

My Feedback: (11)

Today I finaly had a chance to get back to hobby and I torn fown the FG20 for a check out. It looks good no carbon build up at all. And yes I will change the...solty BP gas with Shell V power to se that for a change.
I check out the ignition timing. Like I said when was on Idle I moved the sensor untill I had the high Idle RPM without changing any settings. It looks like 35 degree BTDC is were my engine like it and run fine. Now, will that be a 10 degree on Idle after auto advace ?and 35 degree at WOT?

I want to find more time and try the same thing, moving the Sensor at WOT to see the magic number there.


Adrian

Pull Up Now!

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It's not clear whose ignition you're referring to where the timing module is on a different board from the main ignition board. Can you explain? Modern RC ignition modules have a PIC chip with the timing program embedded within, all on the same little board. On the PICchip, the supplier can blow a fuse that keeps the firmware from being read once burned, so no need to pot the module for secrecy. And for vibration, as you said, a small coating would suffice. Thanks!

Pull Up Now!

My Feedback: (3)

Most ignition advance curves out there top out at around 28 BTDC at around 4k rpm, but I suppose there are some exceptions out there. Who knows what you curve you have, unless it was researched and published somewhere else in this thread. But regardless, the module can only deliver as much advance as the program will allow. So, taking the 28 BTDC as the example, and you set the timing for 35 BTDC, you will be idling around 7 BTDC. This is usually not a good thing, and can lead to stuff like running backwards, and pre-firing when trying to start the engine. You can hurt a finger and/or send your chicken stick flying possibly injuring yourself in the process. I've actually seen and done this during experimentation, so be careful.

It would be child's play for the ignition module to be programmed for a broader curve, so I'd have to think that a lot of research went into it. If it was so obvious that there was performance to be gained by continuing to advance to say 5, 6, or even 7k rpm, why don't they? Heck, you'd have a great idle at 0-2 BTDC and tons of power continuing up until WOT, right? Must be there's not much more to be gained by continuing to advance. I'm no expert, but I'd guess you reach a parametric limit related to flame speed, or something like that.

By what criterion did you declare your idle "good" when adjusting the sensor? RPM? Smoothness? I'm just curious. Usually a good idle is a slow but reliable idle, not a fast one. With such an advanced setting, on final approach with your plane, when you really throttle back trying to get that fast idle rpm down so you don't overfly the approach, your HOT engine could just pre-ignite and throw a rod, run backwards for a few seconds, or just quit.

Ed Vollmer

My Feedback: (14)

Sorry I was not clear. The RCEXL ignition has the timing module on a separate board which is connected to the main board and all potted together. There is even another board separating the output coil(s) from the other boards. IMO, not an effiecient method of manufacture.

You are correct in that "burning the fuses" prevents others from reading the programming. All the more reason that it is silly to go to the extents that are being done to prevent copying the circuits.

I have used or installed or replaced most all of the ignitions available and find the RCEXL to be one of the best available at this time. CH Ignitions, in my opinion, are the best but are (hopefully) temporarily not being made.

Ed V.

Pull Up Now!

My Feedback: (3)

Ed, thanks for the explanaiton. You're quite correct...integrating those three boards into one would be a more efficient way to manufacture them. Maybe they think the container box has to have a certain ratio of length, width, and height. Integrating all those boards might give a long, low container they think wouldn't be pleasing to the customer. Just a thought.

I had a RCEXL module that I accidentally fried, so I cut it apart. And now that you mention it I do remember at least two stacked boards inside. If CH wants to get a product that will sell, I suggest they invest in making a truly miniature ignition module that will scale to smaller gas engines, both 4 stroke and 2 stroke.

tkg

My Feedback: (1)

25 KV is hard to control, mounting the coil on the CDI board gives spark too many opportunities to go some where else.

spaceworm

Early electronic CDI systems (like my Reichmuth) had the coil completely separate from the rest of the electronics. Some Zenoah ECDI conversions use the original Zenoah HV coil, which is separate from their electronics. Not a bad idea, for a lot of reasons.

VBR,

Richard

Ed Vollmer

My Feedback: (14)

If tkg says it is good I will concede one board. The output coil separation board actually does have a grid of copper which would mitigate some RF transfer.

bcchi

Hi Ed,
C&H is closed forever.My health issues was the thing that made the final decision . Too many people selling ignitions and I could not pay labor any more.
I will probably build a few systems later if I get some of my health back.Went to the Dr, with a problem and came home with a big problem.I had a three way open heart bypass went well and back to work in five days,a week or so later I had a train wreck. I had staph infection in my sternum .They removed all the bone of my sternum .Now ribs are floating loose and they pop; up and down will never be the same. I have been flying with the help of friends.
I still have my leg artery problem that I went to Billings to get fixed in the first place. I have given away three airplanes ready to fly.Went to friends who have been helping me. Sorry don't mean to be such a complainer.
I have six of the DL 30s will sell some of them am flying three and will have one more by spring If I make it that long.There I go again,I am lucky to be alive.
I thought TKG was going to take over but this has been a bad year for him and he can not do at this time.Maybe later.I am sorry for any problem that this may cause any of of our 10,000 customers. C&H has been good for Darlene and I and lasted much longer them I thought it would. 33 years.
I will quit this before I start complaining again. It's hard to write with tears in your eyes.
I can build a Ignition that weights 2.2 OZ,complete with spark coil and syncro spark.I still have a few of the Syncros left.
Than You Everyone
BCCHI

Ed Vollmer

My Feedback: (14)

Bill, I am so happy to hear from you. Connie and I have had you in our prayers since I heard you were back in the hospital. Your closing up the shop will be a tremendous loss for the modeling community but I understand the need to do so. Your contributions to the hobby have earned you the respect and admiration of a great many folks. I do not believe we would have the variety of gas engines available if you had not started the ball rolling with the CDI so many years ago.

Relax and take it easy my friend, and please keep in touch from time to time.

Ed V.

w8ye

My Feedback: (16)

Bill,

Good to hear from you

captinjohn

Bill, like others say, it sure is good to hear from you. I sure wish I lived close enough by you where I could just drive over & help in any way I could. I pray you keep getting better & better. I do plan at least one trip out west next year. If I do I would love to stop & visit. Watch you fly and just have fun. Take care for now & God Bless. Capt,n John Hesperia Mich

CH Ignitions

My Feedback: (11)

Hello guys,

I did another modification on a Saito FA 180. I used the Walbro WT-456-1 this is the same carb that I try on FG 20 on which I open the venturi from 6.5mm to 7mm. On the FG20 will not work, I was not able to get the engine to idle lower than 3000 RPM's. I had a WT 424-1 that I wanted to try ...but I said...what the hack let's see, maybe it works on this engine and I will not have it as paper weight onmy desk. I made a real short video due to the time. Soon thatis uploaded on youtubeI will post ithere.
Runs nice and solid, idle good 1700-2000 rpms and WOT 8700-8800 rpm's .Prop is a APC 16 x 10. Igniton RCexel on 4.8v battery(6v was dead)
I will try the other carbs WT 37 and WT 38 when I will get more time on my heands.

Thank You
Adrian

[youtube]http://www.youtube.com/watch?v=0mHE-WzUcqY[/youtube]

w8ye

My Feedback: (16)

It doesn't show

spaceworm

So, was the carb modified or not for these run figures? They look good to me and I may use that carb on my FA180 conversion to gas. Thanks,

Sincerely,

Richard

CH Ignitions

My Feedback: (11)

Yes, it shows now took a little time for youtube to update and Yes the carb is modified. from 6.5 venturi to 7mm. Use a 7mm drillbit and do it by hand easy and carefull. I tried a original 456-1 with 6.5 and will not idle below 3000 rpms for nothing...at list for me. .I did this carb for one of the other engine and it did not work. I thought that I can kiss it good bye. I decided to give it a try and runs darn good. I had the camera going more than 2.5min but how I end up only with this...only heaven knows.
I will do more testings with 2 more carbs on this engine when time will let me. and I will keep you posted.
Now a dumb ?; what is the diffrence between this Fa 180 and the FA180goldenknight? I have one of those too and I did not touch it ...yet. I heard that some guys are installing neadle bearings on the connecting rod. How that. I did not find anything that small to be able to open the connecting rod and install to the 9mm crankpin.
Does any one know a new FA180 engine what compression has?

Thank you
Adrian

w8ye

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some years ago, someone was measuring compression ratio and most were around 9.5 : 1

The current Golden Knights are black with gold valve covers. The others are all silver. Golden Knights cost more. The parts are the same

w8ye

My Feedback: (16)

watched the video and it was good.

Get us a close up photo of the carb installation

Get that engine on a plane and fly it. lets see how it does in the air?

CH Ignitions

My Feedback: (11)

I will take a little video and I will take all a part and put it together so everyone can see.
As far as put it on a plane....I do not have one for this engine.
If any one wants to give it a try I will send it for testing (USA only) .

Thank You
Adrian

Pull Up Now!

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Adrian,

It's not too surprising the Saito 1.8 was able to sustain the idle on the same carb the FG20 wouldn't. The 1.8 is 50% bigger by displacement, so you're shoving 50% more air thru the same wider venturi (7mm) that you had on the FG20, resulting in more air velocity. This added velocity lowers the air pressure in the throat, sucking more gas at idle. Probably, on the FG20, it was dying (at idle) due to fuel starvation.

Also, I installed a needle bearing in my Saito 1.8 gas conversion. This is the engine this entire thread was originally based upon. I had to machine out a groove in the crankcase to accomodate a larger journal home-made rod. It all worked out fine. The tolerances around the crankcase are pushing the limits of wisdom and reliability, but so far so good. Here are the pictures (again) of the machining and the new rod with needle bearing installed: