JetCat Turbine Direct Support Ask your JetCat questions here for the experts that know them. MrMatt and Bob Wilcox will field your inquiries.

High start temperature

Reply
Old 02-22-2009, 10:18 AM
  #1
mun_iz
Thread Starter
 
Join Date: Sep 2005
Location: SingaporeSingapore, SINGAPORE
Posts: 141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default High start temperature

Hi,

For the past 3 starts on my P80, I had been experiencing high starting temperatures between 920-933 deg Celcius. I read in the manual that this might be caused by low gas supply during start up, thereby causing the turbine to overheat. I use 35% propane 65%butane gas. I do not use a gas solenoid valve and during start, I connect my gas bottle directly to the gas inlet of the turbine via a manual gas regulator. When starting, I usually turn the knob of the gas regulator slowly until I hear the gas igniting inside the turbine. Then I would usually increase the gas flow by another 1/2-3/4 turn of the regulator knob while the start process progresses. It had always worked fine.

I was wondering if there are other possible reasons for high starting temperatures besides low gas supply. I do not suspect that the bottle of gas that I was using had depleted since I can still hear liquid sloshing around inside the bottle when I shake it.

Any advise would be appreciated.

Thanks.
mun_iz is offline  
Reply With Quote
Old 02-22-2009, 11:12 AM
  #2
KC36330
 
Join Date: Apr 2006
Location: Enterprise, AL
Posts: 5,952
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

are you holding the start gas can so you get liquid or gas??
KC36330 is offline  
Reply With Quote
Old 02-22-2009, 11:46 AM
  #3
mun_iz
Thread Starter
 
Join Date: Sep 2005
Location: SingaporeSingapore, SINGAPORE
Posts: 141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hi,

Gas I suppose. I usually leave the gas can standing upright (gas regulator on top) on the ground while I turn the regulator knob with one hand and steady the can with the other.
mun_iz is offline  
Reply With Quote
Old 02-22-2009, 11:52 AM
  #4
KC36330
 
Join Date: Apr 2006
Location: Enterprise, AL
Posts: 5,952
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

with a butane/propane mix if it has the clunk in the can (like PowerMax) then you need to hold the can inverted so you get gas.
KC36330 is offline  
Reply With Quote
Old 02-22-2009, 12:08 PM
  #5
mun_iz
Thread Starter
 
Join Date: Sep 2005
Location: SingaporeSingapore, SINGAPORE
Posts: 141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

I am using Rothenberger multigas 300... I am not sure if it has a clunk... I don't hear any knocking sound when I shake the can except for liquid sloshing...

Will liquified gas entering the turbine cause overheating problems?

Thanks for your replies.
mun_iz is offline  
Reply With Quote
Old 02-22-2009, 12:15 PM
  #6
KC36330
 
Join Date: Apr 2006
Location: Enterprise, AL
Posts: 5,952
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

I've never used that brand of start gas but on all the butane/propane mixes I've used you can hear the clunk when shaking the can. feeding liquid to the turbine can give higher start temps, not sure it would be 200 C though but with wind blowing slightly at the tail during starts I've got considerably higher start temps from that.
KC36330 is offline  
Reply With Quote
Old 02-22-2009, 08:23 PM
  #7
mun_iz
Thread Starter
 
Join Date: Sep 2005
Location: SingaporeSingapore, SINGAPORE
Posts: 141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hi,

Thanks for the tip...

I am uncertain if the cause may be due to liquid propane/butane entering the turbine though. The reason I said this is because I had been using the same brand of propane/butane and the same starting up procedure for the last couple of months. I only started to notice increasing start temperatures in the past 2 weeks (last 3 flights)...

My initial suspision was drawn to the amount of propane/butane left in the can which may be causing a drop in gas flow/pressure... however, as I had mentioned when I shake the can, I can still hear a lot of sloshing sounds.

Any other opinions please?
mun_iz is offline  
Reply With Quote
Old 02-22-2009, 09:04 PM
  #8
KC36330
 
Join Date: Apr 2006
Location: Enterprise, AL
Posts: 5,952
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

i don't know what the temps are in Singapore but in cold weather you have to constantly shake the can to get proper gas flow from the butane/propane mix, it's one reason i went to 100% propane off board starting on all my turbines.
KC36330 is offline  
Reply With Quote
Old 02-22-2009, 09:41 PM
  #9
mun_iz
Thread Starter
 
Join Date: Sep 2005
Location: SingaporeSingapore, SINGAPORE
Posts: 141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hi,

That's a good tip... thanks... weather in Singapore is always on the hot side.... 32-35 deg Celcius all year round. However, the past couple of weeks had been rainy and cold... maybe I should shake the can on the next outing and report the results.
mun_iz is offline  
Reply With Quote
Old 02-23-2009, 04:00 PM
  #10
mr_matt
 
mr_matt's Avatar
 
Join Date: Dec 2001
Location: Oak Park, CA,
Posts: 9,911
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature


Quote:
ORIGINAL: mun_iz

Hi,

For the past 3 starts on my P80, I had been experiencing high starting temperatures between 920-933 deg Celcius. I read in the manual that this might be caused by low gas supply during start up, thereby causing the turbine to overheat. I use 35% propane 65%butane gas. I do not use a gas solenoid valve and during start, I connect my gas bottle directly to the gas inlet of the turbine via a manual gas regulator. When starting, I usually turn the knob of the gas regulator slowly until I hear the gas igniting inside the turbine. Then I would usually increase the gas flow by another 1/2-3/4 turn of the regulator knob while the start process progresses. It had always worked fine.

I was wondering if there are other possible reasons for high starting temperatures besides low gas supply. I do not suspect that the bottle of gas that I was using had depleted since I can still hear liquid sloshing around inside the bottle when I shake it.

Any advise would be appreciated.

Thanks.

Yes, there are other reasons. how much total time does the turbine have on it?

Also, is there a reason you are not running in accordance with the manual (i.e. with a starting gas valve connected to the ECU)?

Regards,

mr_matt is offline  
Reply With Quote
Old 02-25-2009, 07:05 AM
  #11
mun_iz
Thread Starter
 
Join Date: Sep 2005
Location: SingaporeSingapore, SINGAPORE
Posts: 141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hi,

The total run time on my P80 is 4 hrs 39 mins.

I ever tried using the gas valve for my first few runs. However, I noticed that with the gas valve attached, there is always a "pop" sound when the gas ignites. I found that the ignitions tend to be smoother without the gas valve and using the procedure I had described earlier.

Can you kindly share the other reasons for high starting temperatures?

I will be flying this coming Saturday and will try with another can of gas for starting.
mun_iz is offline  
Reply With Quote
Old 02-25-2009, 11:53 AM
  #12
mr_matt
 
mr_matt's Avatar
 
Join Date: Dec 2001
Location: Oak Park, CA,
Posts: 9,911
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hello,

First, let me say that 900 degrees on a P-80 is FINE, if I were you I would not worry about it.

My guess is that the pump might have broken in some since new and is pumping more fuel for a given voltage.

If you want to experiment, you can lower the Uaccel1 and Uaccel2 voltages a bit (maybe 1-2 units at a time) and I am sure your temps will drop.

To change these values, hold the "Limits" key down and then press "+". This will bring up a sub menu to change the 2 voltages. After you change the voltages with the "+/-" keys, press any blue button to save the values and exit.

Let me know how it goes.

Regards,



mr_matt is offline  
Reply With Quote
Old 02-26-2009, 06:08 AM
  #13
mun_iz
Thread Starter
 
Join Date: Sep 2005
Location: SingaporeSingapore, SINGAPORE
Posts: 141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hi Mr Matt,

Thanks for your reply and suggestions. I will try out the suggestions this coming weekend and keep you posted on the outcomes.
mun_iz is offline  
Reply With Quote
Old 03-01-2009, 06:33 AM
  #14
mun_iz
Thread Starter
 
Join Date: Sep 2005
Location: SingaporeSingapore, SINGAPORE
Posts: 141
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hi,

Managed to test the P80 today. I reduced both the Uaccel1 and Uaccel2 voltages by 1 decrement step each (from the default factory settings) and used the same bottle of gas and start up procedures. The starting temperature was 860 deg C (as compared to 930deg C earlier). But have a couple of questions to ask:

1) What does the parameter Uaccel2 do to pump operation? I noticed that it is originally at a much higher setting than Uaccel1.

2) Does the decrement in Uaccel 1 and Uaccel2 voltages have any effect on turbine spooling time? Or are these 2 parameters affecting only the starting pump voltages?

Thanks.

mun_iz is offline  
Reply With Quote
Old 03-01-2009, 06:54 AM
  #15
mr_matt
 
mr_matt's Avatar
 
Join Date: Dec 2001
Location: Oak Park, CA,
Posts: 9,911
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hello,

These parameters are for open loop control of the turbine during start up. U1 just gets the kerosene lit, and U2 ramps it up to a steady running state.

Once the turbine is started they are not used hence no effect of performance.

Hope that helps,
mr_matt is offline  
Reply With Quote
Old 03-03-2009, 07:34 PM
  #16
ricardinho
 
Join Date: Jan 2007
Location: tampa, FL
Posts: 1,041
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

i use the green coleman bottles with dreamworks fitting outside the plane. starts right away and is safer then being in the plane.. i am new at turbines and the easier the better..
ricardinho is offline  
Reply With Quote
Old 05-02-2009, 06:34 PM
  #17
giumbo
 
Join Date: Jan 2005
Location: baltimore, MD
Posts: 6
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: High start temperature

Hi ricardinho
Today I received two jet joe turbine very beautiful
giumbo is offline  
Reply With Quote
Reply


Thread Tools
Search this Thread
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -8. The time now is 08:33 AM.