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Advice on alcohol driving, Aster P8/BR38

3078 Views 13 Replies 7 Participants Last post by  Pauli
I did my first attempt at running my newly completed Aster P8 day before yesterday. Unfortunately, I had not charged my fan (inflator & T-tube) enough. Foolishly, I resorted to a scrapped design fan, that of course did not provide enough suction. The track caught on fire 3 times, and as I started seeing the paint coming off some brakeshoes, when flames crept on the outside of the firebox, I decided to extinguish the experiment, adding a weird blue-snow look to the engine.. ;-) The evening was spent cleaning, showering and touching up the paint. Don't use this kind of fire extinguisher!!! (It might even be slightly corrosive  :-(

Today I had charged my fan, and within less than 3 minutes, the locomotive started very unexpectadly to run. Aparently I had left the regulator valve slightly open :D I had only just opened the blower, pressure was something like only 1,5-2 kg/m2 (bar).

The engine met all my expectations on beeing easily moved - the entire following run was done at 2-2,5 bar pressure, with the blower quite open. (During the airtest part of construction, it worked fine with only 0,5-1 bar pressure.)

Also, the boiler aparently produces fantastic amounts of steam. Strong chuffs and a steam plume rising 2 yards in the air was impressive! (Only +7C degrees outside)

My problem is, this locomotive just races away! ;-) It's a question of taming the thing... In fact, my mobile telephone camera was too slow to catch the locomotive in action. That gave me quite a laugh, and a collection of blurred track pictures with steam, but no locomotive :D

Previously I've only run butane fired locomotives. What I miss is a way of controling the fire. Turning the blower off, only make the flames roast the outside of the locomotive.

After 10-15 minutes, I wanted to hault tyhe show, because I was uncertain that the axle pump worked allright, refurbishing water. I ended up squirting up water, from under, into the firebox, to put out the fire. Since my next run is planned for saturday, the wicks will have dried by then.

I have a feeling this engine could do with like almost 50% less fire. I use a three cup burner, with 3 ceramic felt wicks 15x25mm in each cup. Even the boiler casing became quite hot - valve handles gave burns! :confused:

If I only use 1-2 wicks in every cup, I should get a less intense / large flames, right? Maybee so I can regulate the intensity with the blower? Of course steam-up time will prolong.

What is your advice?
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Dry chemical fire extinguisher is a bad idea. Get a straight CO2 type.  Even a bicycle tire inflator (with the small CO2 cartridge) will work for the small accidental fires from a loco.  Save the dry chemical type for the larger conflagrations of wood structures.

BUT, I wonder about the practice of putting the loco's fire out with a cold blast from an extinguisher of any type... the cold blast from an extinguisher could damage the hot components. Just shut off the fuel, keep the blower going and it will go out in a minute or two.  Use any fire extinguisher only in emergencies.

To control the alcohol fire, reduce the alcohol flow to the burners.  Just don't open the valve as far.

You really should not be able to open it "too" far.  I am assuming that this loco has a "chicken feeder" type fuel system.  This consists of a sump that fills from the tank by gravity, and the sump is connected to the burner cups so the level in the cups will be the same as the level in the sump.  (Make sure the loco and tender are on the same level when firing up.)

When the sump is full, the tube that is supplying air back into the tank (to allow alcohol to flow out) gets blocked by the alcohol in the sump and the flow should stop... it "vapor locks".  Once alcohol is burned off from the burner cups the level drops and that breaks the vapor lock and more fuel flows from the tank.  

If you are getting enough fuel that it is dripping on the track you may have air leaks in the fuel system!  If air is leaking in then the sump "vapor lock" cannot limit the upper level of the fuel and it may overflow the cups and the valve may not be able to stem the flow correctly. Make sure the fill cap and opening have no burrs and that you have not over tightened the cap, as that can distort the O-ring and let air in. Make sure the fuel valve as an O-ring on it and it is not damaged.
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Maybe Dave Young will see your post. He runs his Br38 at Steve Speck's and runs like a clock at real slow speeds. See video under current post of Steamin at Steve;s Feb 26th.  Good luck, it is a beautiful running and looking engine
Pauli, do yourself a favor and get a Aster suction fan.  It will be money well spent.  Usually, to reduce alcohol flow you pack the wicks tighter. Keep a hand pump spray bottle full of water near by for fires.  Whenever you stop the engine, open the blower so the fire will not start searching its way out and around the firebox looking for oxygen. All my alcohol fired engines like to run with a little blower open. Daves engine was factory built so I do not know what the wick arrangement is, but the exploded drawing looks like it has a type of ceramic/wick system. At start off, the engine cylinders will have a lot of condensate until they heat up.  (Hot, oily, water out the stack)  Once this clears, his engine runs as well as any Aster I have ever seen. It will run very slow. Dont let any of these frustrations bother you. The first time I ran my Berk the cab was a ball of fire because I had let the wicks flood alcohol and it had pooled under it. /DesktopModules/NTForums/themes/mls/emoticons/cry.gif  Now, I always push my engines down the track after the wicks have soaked, before I lite up.  Just incase there is any alcohol under the engine. I have noticed that on this engine the wicks are so enclosed that it can be a little harder to tell when they are out. Make sure that you have let it sit long enough with the blower open to be sure that the fire is still not smoldering in the fire box before you put engine away.  The CO2 bike inflators are good to have too. This engine seems to be a real Aster sleeper, they can be had at a good price, they are loaded with detail and run great.
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Thanks for all the advice!

Charles, I do not have any leaks, and I use a pump system to avoid spillage. However, because I modified the tender boggie spring system (it was to stiff by factory design), the tender is like 3-4 mm higher = the burner cups fill to a somewhat higher level. However, it seems unlikely that it makes any significant difference, as original & new level both are "half full" burner cups.

Steve, I will not get an Aster fan - this thing of Charles and me is WAY stronger! (se other threads :D

But thanks for suggesting packing the wicks to reduce alcohol fuel! My present arrangement is very "airy" / ventilated, as one other member of Stockholm Livesteamers (though he lives 300 miles away, we ought to rename "Sweden Livesteamers" ;-) suggested that in his experience, only putting enough wick material in to make them stay in the burner cups, the best.

Packing more wicks = reducing return airflow = reducing fuel sounds like a good idea. ( Has anyone put a "return airvalve on a burner?)
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What about cutting the length of wick protruding above the burner cups? After all, that's the way one regulates a kerosene lamp! If one cuts fuel supply, don't one run the danger of burning the wick material? The way kerosene wicks start to incinerate, as fuel runs out?
Posted By Pauli on 02/28/2008 12:47 AM
What about cutting the length of wick protruding above the burner cups? After all, that's the way one regulates a kerosene lamp! If one cuts fuel supply, don't one run the danger of burning the wick material? The way kerosene wicks start to incinerate, as fuel runs out?

Shorter length wicks should produce less flame.  I have found that the wick material seems to get glazed when left to smolder out and then not burn as well.  That's why the CO2 is great to extinguish the fire out in a hurry. On most engines its easy to blast the CO2 on the sides just under the fire box and put the fire out. This engine has a very sealed fire box so be sure the wicks are out. 
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Posted By Pauli on 02/28/2008 12:07 AM
( Has anyone put a "return airvalve on a burner?)
That sounds like a lot more trouble then it would be worth.  My guess is that you are just having the same troubles that we all have had while learning to fire alcohol. /DesktopModules/NTForums/themes/mls/emoticons/blush.gif  If the tank/sump in the tender is set up correct and you get the wicks packed right...........all should work itself out. Remember, you can pack them too tight just like they can be too loose. This all sounds confusing /DesktopModules/NTForums/themes/mls/emoticons/crazy.gif but after you have done it a while, alcohol might just become your favorite fuel.
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As for your running issues, it looks like you were running the engine light -- meaning with no cars behind it. If so, that is part of the problem. Most engines (especially without RC control) are more difficult to control speed when they don't have any load behind them, so you need some cars to create a load. A very soft touch with the regulator helps too.

I built one of these engines and had no problems with speed control -- even down a 1% grade. The secret was having that load behind it.

Good luck,

Ross Schlabach
A couple of people have mentioned my engine running at Steve's.  I suggest you take a look at the video.

The engine is factory built which means it does not have wicks.  It has ceramic "brick" in the fire box.

The engine normally pulls a train of five Merklin three axel passanger cars on occassion a couple of two axel freight cars are added to the train.  Steve's track has a slight grade in one place.  I like to set the throttle so that the engine just barely makes it up the slope (very slow).  I have no trouble regulating the speed.  Of course, you cannot just set it and forget it.  It will need to be adjusted depending on pressure, water level, water by pass valve setting, the status of engine warm up, etc.   It does take a lap or two around the track for the engine to get all warmed up.  The engine (as are all but one of my engines) is manually controlled.

Heat is controlled with the blower on the engine.  I always keep the blower open a little while running.  When running slow more blower is used than when running fast.  This usually gets me more steam than I really need but works well for me.  It is nice to have a little blower should the engine stall and you need to walk to the engine.  This insures airflow in the fire box at all times.  By the way I also keep blowers cracked on my coal fired engines.

For suction I use an Aster fan that is also used on my three coal fired engines.  The Aster fan has plenty of suction even when the batteries are gettin low and need replacement.

Years ago we used to say around here "nothing runs like a Roundhouse"  Well this engine does. (I have several Roundhouse engines).
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Thanks for all your advice!

I will try cutting the wicks - being able to (almost) put out the fire with the blower / adjust heat, would be nice.

Dave - seeing the videos of your engine at Steve's, was the thing that finally made me decide to buy the kit! :D

In Stockholm Livesteamers, we actually put Accucraft in the same "easy, dependable running" category as Roundhouse, with Regner coming a close 3rd. (In my view Maerklin really goes under Regner, as everything but the casing is made by Regner.) Aster among Stockholm Livesteamers, has earned a reputation as somewhat "finicky".

So reading Dave and Steve's endorsements of the P8 here on my largescale, were important.

However, lately I would say locomotive performance primarily depends on the caretaker / driver - which is just what we want out of this hobby! Operation is supposed to be somewhat challenging! With Aster kits however, skill in assembly makes the foundation for operations, adding yet another dimension.

Ross, I agree running with waggons gives "momentum", and smothens the ride! :D This "inogural (spelling?) running week", I will not yet have added RC, nor prepared the 4 Maerklin 3-axle coatches I have ;-)

Dave, does the factory built P8 actually use ceramic brick, not just ceramic felt wicks?!? (Which is what is supplied with the kit.)

I swear I only opened the regulator ever so little... ;-)

However, I think my suspicion that the axle water feed was not working, was actually correct. As the boiler neared dry-boiling, steam generation of course accellerated. Because I've put slightly larger Viton balls in, replacing the original steel, I think I have to increase lateral room over the ball seat. My fault alltogether...
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You will note that in my statement I put brick in quotes so as to differentiate from the more standard type of wicks used on ASTER engines.  I was refering to the ceramic sheets which are discussed in Section 8, step 11 of the assembly instructions.  

Info for those not having the instructions:  For this engine 10 flat pieces of ceramic sheet is used rather than wicks stuffed in round tubes. 

Mine, of course, was assembled at the factory and works perfectly.

If the tender is 3mm higher, the alcohol level in the burner is also higher. It absolutely does make a difference. Your fire is hotter because it is burning more alcohol and the capillary action of the wicks is better because the fuel level is higher. In my experience, you do not need to cut the wicks, you need to pack them tighter. You might also consider adding a small tube to the bottom of the chicken feed (cut at the same angle as the chicken feed down pipe) that is the 3mm length that you added with the springs. That will return the fuel system to factory specs. I would do this first because it is easier than adding ceramic sheet to the burner cups.

I remember DH 07 when I saw a similar thing in a P08. Phil was having trouble keeping his engine going. I finally convinced him I could prove what the issue was by raising his tender. We put a magazine under the tender. That raised the alcohol level, and the engine started to run perfectly. (he had the opposite problem you have)

Tighter wicks means less fire. The amount of heat developed is directly proporational to the alcohol burned. Since there is less capillary action with tighter wicks, you reduce the heat. That also means that you need less water, which is another symptom you described. The axle pump will keep up better.

It really is a balancing act with how much heat and water you need for your individual locomotive. But you have described classic symptoms of over firing. Try adding the tube. Then tighter wicks. I bet you will be quite pleased with the result. Every one of those engines I have seen runs extremely well.


(edited for my poor spelin')
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Thanks John, your reasoning, and reading the other advice, it makes absolute senseto me. I now know the variables to work with.

I did quite extensive testing of burner and wick configurations, with the burner at exactly the right height in comparison to my tender. But then my focus was getting maximum heat, as "everybody" described this as the issue :D

Bought myself a nifty CO2 bicycle tyre-inflator - i will test it tomorrow as fire-extinguisher :D
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