Open thread on Edwards 5 Radial

[WOB]

Plug Driver
5 plug at 3A need a 1.5V(adjustable) 15A regulator from a 12V source.
I was a power supply designer for 40 years and this is no different than a typical PC supply. The only issue is that I do not like home grown electronic project, I do not have all the parts and equipment I am accustomed to have working professionally.

If you plan to always run the engine on a display stand close to a 120 VAC receptacle, An easy glow-plug supply can easily be made from a small power supply transformer ( 50-100VA) by cutting off the secondary winding ( usually on the outside) and making a new secondary from # 16 or 14 insulated wire. There should be enough room to put in enough turns to give 1.5V @ 15 A. Simple and bulletproof. Put in a plastic or wooden box with a primary switch and you are done.

WOB

 

[tornitore45]

WOB that is a great Idea, problem is transformer are kind of rare these days.
Wish I saved all those filament transformers.

 

[WOB]

WOB that is a great Idea, problem is transformer are kind of rare these days.
Wish I saved all those filament transformers.

How about one of these? https://www.mpja.com/Transformers-Power/products/45/

 

[petertha]

I was wondering about building a pack wired in parallel from some of these newer rechargeable 1.5v nominal 3000 mWh capacity cells. Eventually I found a discharge curve & as suspected voltage drops petty dramatically under higher current load. They are great replacements to older chemistry cells that operate under trickle current, but they don't perform well under higher load.

Any battery pack gurus out there? How many cells would it take to build the delivery output to say 2.5A and still get say 1.4v? I can visualize the pack output something like sketch overlay to single cell discharge curve but not sure it exactly works like this. The thinking would be only required for starting, not on for sustained period because capacity will be quite small.
https://ripitapart.com/2015/06/17/performance-analysisreview-of-kentli-ph5-li-ion-1-5v-aa-battery/
https://www.aliexpress.com/item/32703089856.html

My gut tells me some kind of circuit is going to be better using any number of available, inexpensive high capacity RC batteries. Problem is they are all 3.5-4.2v nominal per cell.

 

[tornitore45]

WOB That is the ticket. Saved the link for when I get to that.
Those transformer have winding side by side which make it easier to unwind the secondary, gives full height window to wind the new ~1.8V secondary and make for a very safe solution.
Since I do not plan to operate the engine on an airfield the transformer solution is ideal for me.
And even on a field, most modern car come with a 120V AC output these days, and the heavy transformer does not follow the model airplane.

Peter
If you use N cell (in parallel) to power 5 plugs = 15A you can read the capacity at 15/N Amps on the same diagram and the voltage on a V vs. I diagram.
The voltage seems to be very flat. It look like each cell should not be loaded to more that 2 amp in order to avoid penalizing the capacity, so a pack of 8 cell will work but that is getting expensive.

 

[josodl1953]

This is my setup. I use two 2V 10 Ah lead-acid gel batteries in parallel mode. They have common leads on the - side, the +connections are joined by means of a shunt to enable separate charging since parallel charging of batteries is not a good idea. Each lead can be switched on and off individually so , by means of an ammeter, I can verify if there is an interruption in each circuit , or if a plug is faulty.

 

[tornitore45]

Nice set up, I see the throttle on the side. Show us the entire set up, with the mount, the prop and the fuel/oil tanks.

 

[WOB]

FWIW, the best 4-stroke glow plug on the market is the OS type F according to everything I have read about the subject. In my own experience it worked very well on my 4 cylinder boxer. Anyway, it requires 4 A @ 1.5V. https://www.amazon.com/OS-Engines-7...e+f+glow+plug&qid=1567948909&s=gateway&sr=8-2

 

[tornitore45]

Thanks WOB, that is what I ordered yesterday from Aliexpress, hope they are genuine and not counterfeit like so many thing from China. 6 for $45

 

[josodl1953]

Here are some pictures of the test setup.

The small red box is a battery box to power some LED's below the engine to activate a tachometer held in front of the engine while running.

Jos

 

[tornitore45]

Great set up. What is the white disk in place of the prop?
Did you run it without a prop?

 

[josodl1953]

No , I take the prop off after running to avoid damage ( it's a wooden prop). The disc is just for turning the crankshaft manually.

 

[tornitore45]

Making the pistons now. Shivering at the thought of making and fitting the rings, particularly the "gossamer" oil scraper.

Anyway found an interesting article by Duke Fox haw to determine the right amount of nitromethane.
http://www.modelenginenews.org/
The search function does not work so you select SiteMAp>AlphaIndex and then scroll down to Item 223

 

[petertha]

Thanks. Your search method is worth highlighting here because I seem to get missed (or no) results on the main search box. Maybe due to website status since his passing?

 

[WOB]

Making the pistons now. Shivering at the thought of making and fitting the rings, particularly the "gossamer" oil scraper.

I know next to nothing about the Edwards radial, but I have a basic question. Why does it use oil scraper rings? If it was a spark ignition gas engine with an oil lubed crankcase, I could see the logic, but since it is glow-ignition and presumably depends on piston ring blow-by to lube the lower end, what good does an oil ring do? Am I missing something?

WOB

 

[tornitore45]

The Edward radial has an oil pump squirting oil inside the crankcase.

 

[Noel Gordon]

Hi Guys,
I think that this is 1 of the BEST thread I have seen in a long time. Im just in the process of timing my Edwards 5 and Ive used just 1 slotted hole and I made a dummy shaft that will just slide through the bearings to save the frustration of multi assembly and disassembly.. Ive made sooo many changes to the original drawing with piston design and my engine will run on pump gas with an ignition pack and my sparkplugs come in from the side into a combustion chamber as if was a truck diesel engine..I am going to run my engine on 5 to 10 weight oil...I do not intend to spend a huge amount of running in time of a dozen strokes of the piston will see the rings bedded in as I have 3 degree taper on the ring face as high tec racing engines have and just a final note I have made the tapers on the split drive collar 6 degrees BECAUSE any taper under 7 degrees is self locking just the same a your drill taper in your tail stock..
Ive enjoyed this thread very much so please keep it going..Good health to you all.

 

[Noel Gordon]

WOB. just a quick suggestion re the oil ring....just make the oil ring the same as the compression rings but under the oil ring cut an undercut with your ring parting tool about 0.030 deep and drill some 1mm drain holes.. Did you know that the top compression ring contributes 18% to oil control..(True fact) hope this mod makes your piston and piston ring making so mush simpler and quicker..Sure saves time making silly and fiddly oil rings..I have made all of my pistons as slipper pistons which reduces the friction and makes the engine so much sweeter..Im going to put my engine into a 110" Skyraider.

 

[WOB]

The Edward radial has an oil pump squirting oil inside the crankcase.

Is the fuel normal glow fuel or is it methanol and nitro only?

WOB

 

[tornitore45]

This is my first 4 strokes Glow and the fuel issue is not settled.
What is a available in the commercial fuel market is call 4 Strokes Glow which appears to contain around 20% Castor/Synthetic oil. In theory a crankcase lubricated 4 strokes should need no oil in the fuel but methanol has zero lubricating property and small model engines need abundant lubrication.

Is hard to make heads and tail because the fuel vendor are secretive still today.

See this link http://www.modelenginenews.org/
Select Site Map >> Alpha Index >> Scroll down to item 224