c/f

My Feedback: (1)

I removed the SS tailpipe from a jet this winter for some routine maintenance, The outer tube was firmly held in place atop the v shaped ring on each end as I recall, as this is a 10 year old JET,
Somewhere in handling and time between getting back to it, it slides off freely and I cant really tell if it was spot welded atop the V or it there was just a dimensional friction fit atop of V ring now loosened. Its possible once reinstalled the rear bulkhead exit would keep it in place without sliding off and the swelling of inner with heat would insure it stays put ?????

This is a fully bypassed setup on a Viper jet and a PEGASUS HP that really sounds unique and has had many compliments as to its sound, Hate to discard and try something else.

I really dont know where to go from here, Do I add straps to outer as well to secure front side??
Send it off somewhere or try local weld shops??

Any suggestions???

c/f

My Feedback: (1)

WOW, this is sad, 155 views and not a clue??? No wonder RCG jets is tacking off. JIMMY H...... any help???

rhklenke

My Feedback: (24)

I'm not sure that anyone reading it knows exactly what the situation is. It sounds like the inner and outer pipe are no longer connected, true?

I don't believe that most welding shops will have a spot welder that will work on material that thin or in a space that tight between the inner and outer pipe, but I could be wrong. I would definitely try and get it spot welded back in place. If you can't find someone local to do it, you might see if you could get Tam to do it.

I'm not sure if it would be possible to strap the outer pipe in place well enough to keep it from moving without crushing or denting it...

Bob

Bobneal1

My Feedback: (21)

You could drill through both pipes and put a screw with a nut on one end. use an aluminum spacer that you can buy at a hardware store or Home Depot etc. Just cut the spacer to the correct length to go between the inner and outer pipes. I like pop rivets for this they work well. You will have to stop squeezing the gun when the proper length is attained. then remove the gun/ pliers and cut the stem with side cutters.

Dave Wilshere

The outer cool wall should never be fixed both ends! The inner pipe expands a lot when it gets hot, the outer does not. The outer tube does not need fixing to the inner at all...just spacing off it. If the inner pipe is fixed at the front, spacers on the inner hold the outer off. Fix the outer at the rear fuselage so the outer protrudes past the inner 3/8" and you are good to go

Dr Honda

My Feedback: (4)

Just because you have views, doesn't mean that those people know. So... do you want a crap answer? Also... the standing rule is... give it 24 hrs. Having an attitude after only a few hours will get you ignored.


Anyway...

As Dave said... it shouldn't be locked in at both sides. The outer shell is supposed to be ( relatively ) cool because air flows down between the pipes, so the expansion is different. Most of the pipes I've played with aren't welded at all. (inner and outer) They are held separately in the model. The inner pipe is held close to the engine, and it grows rear-ward... and the outer is held at the rear, and allowed to float on the inner piper. The outer pipe should be a little longer in the back, in comparison to the inner pipe, and that will create the venturi to draw air between.

FalconWings

My Feedback: (57)

No it's not.

Andrew Bird

What is 'tacking off', anyway? A mixture of taking off and whacking off? Sounds messy........

c/f

My Feedback: (1)

Thanks, for reply, this is in a Pegasus HP powered Cermark Viper II, that has flown for 10+ years and has even taken a Best Civilian Jet at Route66 as well as IRON MAN at Kentucky Jets so it has many flights proven on tailpipe at Eagle Tree Pitot speeds routine of 199.99MPH

As an engineer I am well versed on heat expansion/contraction, thus my question/confusion with tailpipes "BY DESIGN". So my take away is the corrugated standoff ring that "is" spot welded to "inner pipe" is just an "OD" dimensional friction fit to outer wall cooling pipe and mine has now lost some of its friction fit tolerance between the two.

The inner Pipe has two straps holding it to the kevlar full bypass, so I was thinking a security strap attached on the front end in like manner attached to wooden bulkead would not inhibit any dimensional expand/contract in diameter/length only acting a as piece of mind since it now will freely fall off if stood on end on the bench out of the model. This is something in never did before and no other pipe I own exhibit.

c/f

My Feedback: (1)

What is 'tacking off', anyway? A mixture of taking off and whacking off? Sounds messy.......

"EXACTLY" spelling/grammar critical comments, talk about a circle jerk???

The NOOB questions being asked of TURBINE EPO jets, and the advice given, as to how to get an autorestart kero start, China assembled BNF ARF started the first time I read in amazement. Just a dialogue of paramaters first , and integrity of assembly questions an after thought if all else fails.

It truely is uncle bobs worst nightmare as the "COOL" gift crowd now enter the turbine jets arena. I also see the "DR" posting more and more. The amount of turnkey jets and related @RCG is rivaling any other, which to me "CLASSIFIEDS ARE THE HEARTBEAT" of a forum that's alive and well.................02

rhklenke

My Feedback: (24)

Tam uses 2 "Z" folded strips of metal to space out his inner and outer pipes. I know that the strips are spot welded to the inner pipe on at least one end and I thought that they were also spot welded to the outer pipe as well. I'll have to take a look at one when I get home to see.

The CARF pipes typically have tabs welded to the inner pipe that come up through slots in the other pipe and are bent over to retain it.

Either way, I've never had or seen a 2-walled pipe where the inner and outer walls are not mechanically connected together. I know your's was and then came apart, and my suggestion is to connect them back together using some of the above advice. I suppose you could secure the outer pipe to the airframe somehow to retain it, but I've never seen it done myself.

Bob

Andrew Bird

Lol - good work A semi incomprehensible rant about how everyone else is the problem after you were the one to come on and moan that others hadn't immediately taken their precious time to answer your question. My comment was tongue in cheek for a bit of fun - something this place lacks versus the old days. And you've done a very good job of demonstrating that.

ravill

My Feedback: (11)

Are you speaking Amurican?

I hope your engineering reports are more comprendable, capiche?