Go Back  RCU Forums > RC Airplanes > RC Jets
Reload this Page >

Thrust tube wrinkles....

Notices
RC Jets Discuss RC jets in this forum plus rc turbines and ducted fan power systems

Thrust tube wrinkles....

Old 06-09-2017, 02:09 AM
  #1  
Ceeray
Thread Starter
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 309
Likes: 0
Received 2 Likes on 2 Posts
Default Thrust tube wrinkles....

I took a pic of my Mig-29 thrust tube (SM, bifurbicated) , 17 flights with atj 220 sv turbine.

I just fund out those wrinkles and grounded the plane until someone tells me its ok to fly..
Attached Thumbnails Click image for larger version

Name:	IMG-20170609-WA0004.jpeg
Views:	411
Size:	1.03 MB
ID:	2219340  
Old 06-09-2017, 03:00 AM
  #2  
David Gladwin
 
David Gladwin's Avatar
 
Join Date: Feb 2002
Location: CookhamBerkshire, UNITED KINGDOM
Posts: 3,587
Received 10 Likes on 10 Posts
Default

Needs to be replaced. Wrinkling such as thus can be easily followed by cracking leading to a hot gas leak and fire.

I think the gauge of steel used for the pipe needs to be increased and remember that the pipe needs to have a degree of freedom to cope with expansion.

David G.
Old 06-09-2017, 03:26 AM
  #3  
Ceeray
Thread Starter
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 309
Likes: 0
Received 2 Likes on 2 Posts
Default

Oh bugger there goes my summer flying. The pipe is free to move but still sags..
Old 06-09-2017, 04:44 AM
  #4  
Bobneal1
My Feedback: (21)
 
Join Date: Jan 2002
Location: Chester, VA
Posts: 244
Likes: 0
Received 1 Like on 1 Post
Default

Were the wrinkles there before you ran the engine the first time? I. e. manufacturing defects ? if so it might be ok. But if it were mine I would have to have a telemetry temp sensor in the area to continue to use it for flying . I would want to be alerted of any unusual temp rise. It might be a wise thing to do anyway.
Old 06-09-2017, 05:02 AM
  #5  
ChuckC
My Feedback: (24)
 
Join Date: Jan 2002
Location: Friendswood, TX
Posts: 654
Likes: 0
Received 0 Likes on 0 Posts
Default

Hard to really tell-there's no significant discoloration at the wrinkles, but wrinkles are a bad sign. To the previous post-those could also come from rough handling of the pipe, if material is thin. Post more pictures for the group.

And, it is better safe than sorry...
Old 06-09-2017, 05:29 AM
  #6  
Jack Diaz
My Feedback: (1)
 
Join Date: Nov 2003
Location: Caracas, VENEZUELA
Posts: 551
Likes: 0
Received 0 Likes on 0 Posts
Default

Agree with Chuck.
Looks like the pipe was pushed forward pretty hard.
No signs of overtemp.
How is the other side?

Jack
Old 06-09-2017, 07:27 AM
  #7  
Ceeray
Thread Starter
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 309
Likes: 0
Received 2 Likes on 2 Posts
Default

Other side 50% better. Will get more pics later
Old 06-09-2017, 07:57 PM
  #8  
CARS II
My Feedback: (7)
 
CARS II's Avatar
 
Join Date: Oct 2002
Location: Sacramento CA
Posts: 5,881
Received 44 Likes on 40 Posts
Default

There is discoloration where the wrinkles are, it maybe coming from a hot section on the exhaust cone, if it continues it will make the pipe fold, better to get a new one soon.

Run the engine outside the jet, check the tail cone for any hot jets coming out of it, if you see that then the new pipe will endup getting burned like the old one if that is not taken care of before.
Old 06-10-2017, 01:02 PM
  #9  
ash 26
 
Join Date: Apr 2006
Location: private, IRELAND
Posts: 424
Received 0 Likes on 0 Posts
Default

Originally Posted by Ceeray View Post
Oh bugger there goes my summer flying. The pipe is free to move but still sags..
Hi
get onto IQ Hammer he will make you a proper one and you will be in the air in no time

Schubrohre | Hammer Engines GmbH
Old 06-11-2017, 03:24 AM
  #10  
Ceeray
Thread Starter
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 309
Likes: 0
Received 2 Likes on 2 Posts
Default

I contacted Grumania which looked on the pics and said its safe to use but any wet start should be avoided. I also took the pipe out and checked it. All wrinkling in in the angled seam on the welding spots. So it must get hot there.. I will increase cool air amount for the turbine by increasing tube distance from turbine, even tho its already 3cm. And I possibly have to make additional air vents under the turbine for clear air.

I have to check out the pipe after every flight how its faring.

New pipe from Grumania 450€ish, new Skymaster Pipe 450$.... Tamjets has not answered yet with a quote.
Attached Thumbnails Click image for larger version

Name:	20170610_220441.jpg
Views:	114
Size:	3.23 MB
ID:	2219569   Click image for larger version

Name:	20170610_220434.jpg
Views:	98
Size:	2.69 MB
ID:	2219570  
Old 06-11-2017, 09:09 AM
  #11  
mr_matt
My Feedback: (10)
 
mr_matt's Avatar
 
Join Date: Dec 2001
Location: Oak Park, CA,
Posts: 10,383
Likes: 0
Received 1 Like on 1 Post
Default

I would go ahead and get a new pipe to have as a spare. Pipes don't last forever, and you will continually be trying to make this decision until you finally decide to break down and get a new pipe. At least if you have the pipe already you won't be grounded nor will you be tempted to squeeze in a last flight on a compromised pipe. FWIW
Old 06-11-2017, 09:51 AM
  #12  
Ceeray
Thread Starter
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 309
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by mr_matt View Post
I would go ahead and get a new pipe to have as a spare. Pipes don't last forever, and you will continually be trying to make this decision until you finally decide to break down and get a new pipe. At least if you have the pipe already you won't be grounded nor will you be tempted to squeeze in a last flight on a compromised pipe. FWIW
Not a bad idea..!

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


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.