[AJCoholic]

Originally Posted by volksman

i was going to hold my tongue but every one likes to yap safety, 125k rpm with a bearing failure that you will not hear will give ya a shredded turbine wheel, hope you are not sitting beside it with your fire extinguisher and no hearing protection . it is really pointless to give any comment on rc canada most of the time but these things are definately not toys and if a catastrophic failure occurs because of neglect thats your own fault, but pray no one has inconnel imbedded in their forehead due to if its not broke dont fix it

If you read my post, I did say to take note of the rpm vs temps vs pump % (which will give a sign of something changing like a wearing bearing, or an impending pump failure, etc) which most pilots make a note of (or should). And also, the small number of turbine pilots within Canada have shown to be very safety cautious and really take care of their equipment.

Its pretty uncalled for to come in here spouting doom and gloom - because some of us base turbine maintenence on actual experience. I can tell when a bearing is not 100%. Yiou can HEAR when it is not at its prime, as well as taking note of how long it takes to spool down, the noise, etc. All of which come from experience actually running turbines and learning what to watch for. Anyhow, your post was pretty uncalled for. What exactly is your model turbine experience? Me, I have built two, and one more from a kit, and have or had three manufactured ones. I am not talking from my armchair.

Besides that, a bearing failure is VERY un-dramatic, if thats a word. The engine will quit and/or rub. Nothing is going to "explode". If you dont believe me, ask a few people who have had bearing issues. You may get some flaming, but no "catastophic failure".

I dont mean to be rude at all - just calling the facts out.

To repeat the OP question, running the engine detuned will do nothing wrong. Absolutley nothing.

AJC

[volksman]

well i guess god cohollic has spoken, i wasted two yrs in gas turbine overhaul and repair.

[AJCoholic]

Originally Posted by volksman

well i guess god cohollic has spoken, i wasted two yrs in gas turbine overhaul and repair.

What is your actual experience with MODEL TURBINES? I doint care what youre full scale experience is, as it is in no way related to our models.

I am sick of all the pro's on the internet who havent even owned or run what they are giving advice about. If you have some model turbines and have some experinces to share, please accept my appology. If not, well maybe you should stick to giving advice to full scale A&P's.

Once again, I speak only from my own experience. And I have had bearings fail.

AJC

[Angus]

Well said Andrew, you just saved me a lot of typing

Thanks

Angus

[volksman]

well well who got your expert panties in a knot. model or full size principles are the same i guess all engine forums should have heading of aj coholic expert moderator. dont worry i will give no advice or responce to a question here again

[Len]

Originally Posted by volksman

i was going to hold my tongue but every one likes to yap safety, 125k rpm with a bearing failure that you will not hear will give ya a shredded turbine wheel, hope you are not sitting beside it with your fire extinguisher and no hearing protection . it is really pointless to give any comment on rc canada most of the time but these things are definately not toys and if a catastrophic failure occurs because of neglect thats your own fault, but pray no one has inconnel imbedded in their forehead due to if its not broke dont fix it

Originally Posted by volksman

well i guess god cohollic has spoken, i wasted two yrs in gas turbine overhaul and repair.

Originally Posted by volksman

well well who got your expert panties in a knot. model or full size principles are the same i guess all engine forums should have heading of aj coholic expert moderator. dont worry i will give no advice or responce to a question here again

As can be atested from a search on my postings here on RCC, I do hold my tongue, most of the time. This is NOT one of those times:
I have been witness to a turbine wheel failure in a Canadian home built turbine back in Moose Jaw in the early days. There were no apparent initial issues with the bearings though after the wheel failed one can imagine the bearings were trashed as well. There were 3 blades gone from the wheel and one was still inside the case. The other two were not to be found. This happened in an internal installation and we assume the other two blades exited the tail duct, as there was no evidence of them going through either the engine case or the fuselage. The plane flies still to this day.

Whether the wheel failed first or the rear bearing failed first causing the rub is undetermined. What we did determine is that even with a stainless steel Chamber and an oil filter as a case nothing with damaging heat or kinetic energy exited the sides of the engine. Possibly they exited the rear, but if someone is standing behind a running turbine they need a new head anyway!

What has caused my irate response here is the irrational attack on Andrew's character with the "god coholic" reference. Nothing could be further from the truth! While Andrew is an engine expert in my opinion, he has never professed it as so, nor is he brazen or brash. Boiling it down Volksman, <real name?> that was uncalled for and you should be apologizing profusely and/or sanctioned from posting on RCC by the moderators. However; I note from your last post "dont worry i will give no advice or responce to a question here again" that you are sanctioning yourself, and I for one appreciate your doing so.
Sincerely,
Len Gladstone

[volksman]

great len i know the admin in passing he wants to ban me great. not the first time andrew has slighted me so hey no more advice to guys asking questions very simply. you again should also hold your tongue do you know me. no and i will not offer an apology. too many times i see contradicory stupidty that turns onto a bash cause ya say something that offends the supposed experts. so jason do your thing as len wants

[Gizmoman]

I hope no one minds me posting a link to another forum. This link provides a good basis for comparison of bearings.
http://video.helifreak.com/?subpath=...ing-sounds.wmv

Giz

[lilphil26]

Is it just me, or do I start threads that * people off? Thanks to all of you with your responses, dealing with my issue in hand.

[AJCoholic]

Originally Posted by volksman

great len i know the admin in passing he wants to ban me great. not the first time andrew has slighted me so hey no more advice to guys asking questions very simply. you again should also hold your tongue do you know me. no and i will not offer an apology. too many times i see contradicory stupidty that turns onto a bash cause ya say something that offends the supposed experts. so jason do your thing as len wants

I dont recall having a conversation with you - and if I "slighted" you please let me know about it.

I am a person to stand behind what I think I know about, and I have never, ever proclaimed myself an expert or anything near to it on any level in this hobby. When it comes to engines, and in this case turbines in particular, I have read every book in the English language on the topic - been a GTBA member for years and have studied the years of documents over and over again, and have been a model turbine modeler for 8 years. I have experience building my own engines, and working on overhauling others, etc. What I speak of, is of my own hands on experiences combined with the knowledge of others.

I am not one to get into arguements for the sake of arguing. But lets at least give opinions based on SOME kind of first hand use of the damn things we are trying to discuss! Geesh...

I guess I see this too many times.. and am getting sick of it. So I decided to say something about it.

ANyhow, the idea of running a turbine below its max (safe) operating rpm is not new. Many modelers have bought engines larger than needed, and detuned the controller/ecu to allow less rpm = less thrust at max throttle.

The other benefits are:

- faster spool time from idle to full stick up and back again
- less wear on the bearings as stated previously
- some engines will actually exhibit lower fuel consumption (ie, a 30 lb engine set to 20 lbs max thrust will probably use less fuel than a 20 lb thrust engine running at max throttle producing the same 20 lbs thrust)
- cooler EGT at max rpm

AJC