Starting gas and set up
 

I'm having some trouble with my first turbine and have three unsuccessfull starts to date. Wren44 w/ onboard starter. I'm running straight propane and was told that could be part of the problem. Another is the great northern gas regulator, the settings don't seem to change anything. It's taking forever to get the gas lit and after I do almost a minute to get up to 100 degrees for fuel ramp. One time with quite a flame up because the ecu dumped in fuel and I failed to react quick enough with the starter. All the time the starter battery has to run is taking it's toll. Outside temp. was not an issue as it was fairly warm out,about 57 F. What gasses are being used and how can you reliably set the pressure? I'm not putting thie turbine anywhere near an airframe at this point. I have a small regulator at work that I will try to fit to a butane refill that I have for my solder gun. Please I don't want to go back to ducted fans!!! Doug

RE: Starting gas and set up
 

Doug,
I use Coleman PowerMax fuel with my JetCat P60. Check your local camping/sporting goods store. "Dicks" carries it here in Cleveland, Ohio.

RE: Starting gas and set up
 

The Powermax is a mixture of butane and propane. The reason to use this for onboard gas is that the pressure is lower than straight propane and it doesn't blow fittings off. Sounds like you need more pressure and not less. What RPMs are you trying to start with? If they are too high it will not heat up unless you get more gas. The regulator I use is from a propane stove and I set it to the highest setting (lighting). If I want to speed things up I can push the knob down and get a lot more but it only saves a few seconds. The top RPM of my onboard starter is 16,000. Any more and it would take longer to heat up. Before I found the regulator in the junk box of a hardware store I used the modified torch tip below. It worked just as well.

RE: Starting gas and set up
 

PS...the I'm thinking the 44 would not be that much different from the 54 to start but I could be wrong.

RE: Starting gas and set up
 

I like that gas stove set up!!. I'm using the same canister as you with the G N regulator. When the gas lights wren told me to run the starter continuous but it's taking so long to reach temp. 100 degrees C. is when fuel starts, but the RPM could be any where at that time thats probably why I got the flame up on second run. Third run went a little better , only 1/2 minute till fuel ramp and much smaller flame this time and blueish in color. I hit the starter as instructed as fuel ramped and engine ran up to 45000 rpm before cutting out completely. Display said flame out??? Do the fuel pumps have to be broken in? Doug

RE: Starting gas and set up
 

First let me say that this is my first turbine and I am not an expert....
It took me a few starts to get the hang of it and part of my problem was with a bad pump. I have a JDE/Wren 54 that I bought used ...but only factory run. JDE does not use that pump anymore as they had problems with it leaking. I don't know if you have to set the "Pump Start Point" on yours but my start point on that pump was over 35. The Wren instructions said to discard the pump if it is higher than 35. The ramp light was blinking but I wasn't getting fuel right away. Thus my starter pack was running down as yours did (even though the temp was up)

I thought it needed more breaking in and ran it at low speed for a looonng time. Then it started to leak so I ordered a pump from Moore's. Even though this new one has a speed 400 motor instead of a 380, my start point went down to 18!! I did a breakin on it and the start point went down to 13, but it took a few seconds to actually start pumping. It starts reliably at 18 so I left it there. I did the break in under water to flush away the carbon. Now even at full speed there are no sparks or arcing in the motor.

Another thing to check is the thermocouple. Make sure it is in the right position to read the temperature.

RE: Starting gas and set up
 

Very good advice, that alone might be causing a serious under-read of the temp.

The engine comes with a gas tap, what happened to it?

I use butane/propane mix.

With my MW44, same on board start as yours Doug, I had similar problems. As soon as the gas popped I got back on the starter and the temp just would not come up, or it blew the flame out.

That identified two problems:

1. gas pressure was too low, the temp was around 10C or less. Put the gas bottle under my arm inside my jacket for 5 mins, gave it a good shake to break up the liquid and tried again, MUCH better.

2. Although the instructions for this version do say get back on the starter and hold it down as soon as the gas lights, most times I found that too much for the gas, it was running too fast and blowing too much air through for the temp to rise so I blipped the starter at around 7 - 10k rpm while watching the data terminal, and as soon as it says fuel ramp hold the starter switch down - don't delay getting back on the switch the moment it says fuel ramp or you do get flames. Another option would be to hold the switch down just as the temp is about to hit the fuel ramp condition - maybe 98 or 99C

Once the fuel ramp is active you have to be quick to disconnect the glow and turn off the gas or you get flames.

RE: Starting gas and set up
 

Harry C has got it right. My 44 is manual start and I just back off the rpm's with the starter button on the wand until the gas is over 100oC. I use Powermax and keep the can as warm as possible in the prevailing ambient temperatures. I had a slow start yesteday because the air temp was only about 45oF it ramped onto fuel after about 30 seconds and after that no problems.

John Agnew

RE: Starting gas and set up
 

I'll be making my fourth attempt today. Bought a 2 - volt Cyclon d-cell now gas fires off as soon as you turn it on. I was going to try powermax but the connector does not fit my gas valve ,so will try propane again. All air bubbles are out of fuel line and is filled to shutoff valve. Will keep the RPMs down so airflow does not cool the temp. reading. Wish me Luck!! Doug

RE: Starting gas and set up
 

Sounds to me like your starting technique is a little incorrect.

Here's how I do it.



Spin the starter to about 5000RPM and turn off.

As the RPM slows open the gas valve a small amount and wait for the pop as it lights.

BLIP the starter to slowly increase the RPM

Watch the temperature. If it is below 100 deg open the gas a bit more and slow down your rate of 'blipping'.

Keep doing this until 100 deg is reached then increase rate of 'blipping' further. keep an eye on the temp to keep it above 100 deg, opening the gas valve as needed.

When the fuel lights (temperature will increase rapidly), turn the starter on fully until 35000 RPM is reached.



After two dodgy first starts getting the hang of it, I ended up with the above starting procedure. I have not had a poor, or failed, start since.



I originally used an aftermarket gas valve that was a bit rubbish. The Wren one is probably the best one you can get for the engine.

Be careful with the number of starts. If you spend a long time running the engine on the gas alone you risk damaging the bearings, as there is no lubrication. If this carries on, I would take it to someone that is used to this engine to check it out.

RE: Starting gas and set up
 

The problem is that the instruction manual for this version of the MW44, the one with on-board starter, specifically says that when the gas lights you hold down the starter switch continuously and do not blip it like you do with the starting wand version.

RE: Starting gas and set up
 

Apologies for this, I have not seen the onboard starter manual.

However, I have seen MW54 and KJ66 started with the same technique with onboard starter. I am not sure what difference there is between the different starter mechanism's but I would have thought they would be very similar.


I am sure there is a good reason if Wren has said to do it like that.


Also, with my manual start version I have no problem with flames. I don't have to be very quick once fuel ramp has started and the gas and glow can stay on forever with no problems. It sounds odd that the onboard starter version would be that different.

RE: Starting gas and set up
 

Siclick 33, Thanks that is all good stuff and I'm wondering if your talking about the same aftermarket valve that i have. Harry is correct about the manual. I think the diff. is rpm of the wand starter vs. the on board starter.The main problem seems to be that the gas [propane] will not take the temp. far enough above 100 C to maintain fuel ramp. I didn't get a regulator with engine although it is shown in parts list. No success on forth try yesterday. All this talk about easier than piston engines is nonsense. Stay tuned Doug P.S. Wren mentioned something about a restrictor in gas line to engine.

RE: Starting gas and set up
 

That's a pity Doug. Once I got the gas warmed up and shaken up, and ignored Wren's instruction to hold the starter on all the time, I always quickly got up to temp and the fuel flowed. The problem was not having no flame, the problem was far too much and getting many shut downs due to the flames coming out the back hitting over 800C and the engine shutting down automatically. No doubt that's why Wren want the starter on full-time, but when I did that then many times it did not get to minimum ramp temp. In fact on several occasions the starter blew out the gas flame, when I switched the motor off and the engine wound down enough the gas would relight. Having had that a few times was what made me decide to try blipping it and that got it to the fuel stage, but you have to be so careful not to get a fire at the back end, hence my advice to be back on the starter immediately the fuel ramp is indicated, or a degree or so before that point.

What rpm range were you blipping it at? What temp was the gas in the bottle at? You used propane? Does butane burn hotter? I used a butane propane mix approx 70:30. My full auto-start PST has the same problem as the manual start MW44 if the gas is not warm and shaken, it sits stubbornly well below fuel ramp temp, and it seems to have a speed controlled motor while awaiting the fuel ramp so it doesn't keep accelerating like the MW44. Getting the gas bottle thoroughly warm, then giving it a good shake, is essential to getting the gas stage up to temp. Until that bit is sorted, it's hard to lay any blame on the engine or starting technique.

RE: Starting gas and set up
 

If you are using straight propane, that may be part of the problem. A propane/butane mix is much preferred. I busted my gas valve, so couldn't use starting gas for my 54, I found that the presurized butane cylinders (the little ones for refilling lighters) worked beautifully in a pinch...

RE: Starting gas and set up
 

Your not gonna believe it, on the fifth attempt SUCCESS!!!!!!!!.The start went without a hitch.Glow plug on, blip starter,gas on ,pops as soon as rpm drops,then you have to nurse it to get 100C about 1/2 minute as soon as ramping fuel hits the engine on the starter full. It takes a few seconds for the kero to ignite but when it does I'm off the gas. Kept starter engaged till 37,000, motor sputtered a little but continued up to 58,000 then settled to 55,000rpm [idle].Ran about 30 oz. of fuel through at diff. rpm"s. Top speed was 191,000 RPM !!!!! Absolutely AWESOME. This was followed by three failed attemps, just as I was gaining confidence. Same symtoms each time. Started as above but as engine approached 55,000 it just cuts out. Data display says "flameout" Why would it flame out? , fuel was flowing but ECU cut it off. Is it possible that since my starter battery is one of those 9.6 volt toy type batts. that I'm getting an overtemperature because it is slow to excellerate? I'm clueless. Doug i'm so close Bateman

RE: Starting gas and set up
 

I thought the starter battery should be a 6 cell (7.2V) pack? This may help you as the starter motor won't spin so quickly during start.

The starter is turned off at about 35,000 RPM. If the engine does not flame out until 55,000 RPM then I think you have another problem. The only two flame-outs I've had with the 44 were caused by air in the fuel line. Check all your connections and have a look to see if there is air in the line after you have removed the starter.

You say the engine was spluttering. Was this just as the engine started or did it continue throughout? If it continued this may indicated air also.

Also check that your ECU battery is fully charged.

Let us know what happens.

RE: Starting gas and set up
 

Ignore my last comment re the battery. I didn't realise the motor used in the onboard starter is different to that in the hand starter.

RE: Starting gas and set up
 

Another success on 9th attemp.Recharged starter battery prior to and all went well. It is really tough resisting the urge to use it as a leaf blower!!! Standing about 15 feet behind engine is like being on the tarmac at Phila. International Airport. I'm sticking with my theory about starter battery as we checked rpm before and after test run. There was a drop off so we didn't attempt another run. Maybe I'll try a 7.2 racing pack. How do you connect up the powermax can? I saw one in Dick's sports but the top is different than normal gas bottle. Doug......

RE: Starting gas and set up
 

What RPMs are you getting with the onboard starter. Are they more than Wren states?
In would try the 7.2 pack. The lower RPM (and faster heating) may save you having to blip the starter so much and maybe not at all. Switching to Powermax is just more stuff to buy in my opinion.;)

RE: Starting gas and set up
 

Get a valve like this one: http://www.dreamworksrc.com/catalog/...roducts_id=544

I've used one on my FTE T-500 and it works great....

Cheers,

RE: Starting gas and set up
 

Don't do it Doug!!!! there's a reason Wren specifies an 8 cell pack and it is that a 6 or 7 cell pack will not drive the starter motor up to the 35k rpm point where you disengage the starter. You must push the engine up to that rpm on the starter, for it won't self-sustain below it.

You switched the starter off at 35k rpm. From then on it played no part in the running of the engine. The engine accelerated on its own from 35k to 55k rpm. Then it flamed out. That proves the flame out had nothing at all to do with the starter motor or its battery. You have air in the line, or low pump voltage causing insufficient fuel flow or something like that. The little battery provided with the engine is only going to have enough capacity to run the pump for one or two flights, it will need frequent re-charging. Did you re-charge it after the first successful run? Have you properly cycled it from new with a timed 14 hour C/10 charge then discharge a couple of times to get it working. Some nimhs can take a handul of cycles to get up to speed.

It's a beast at 190,000rpm isn't it :D

RE: Starting gas and set up
 

Tim, I'm going to pick up one of those this week.Could be the ticket for quick gas heat up. Harry, in looking at my notes your correct about the 8-cell. I just need to find something with a little more capacity [mah]. I slow charged the fuel pump battery a couple times since I got it but have not cycled it yet. Will try running down tonight then 15 hour on charger. Areyou sure about two flights.Wren said pump uses very little juice. Thanks to all and yes the little wren 44 is moving some air at 190,000 !!!!!!!!!!!! Doug

RE: Starting gas and set up
 

I'm judging by the amount of battery capacity my PST uses per flight, it's pump motor is actually smaller than the MW44's. Perhaps the 44's pump does use a lot less.

I use 2400mah nicads for the starter motor.

RE: Starting gas and set up
 

If Wren says 8 cell, then go with that. Just use the blip method to heat up.