News:


  • March 28, 2024, 06:34:10 AM

Login with username, password and session length

Author Topic: How to secure coupler between pipe and header  (Read 1970 times)

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
How to secure coupler between pipe and header
« on: February 05, 2018, 07:09:40 PM »
Being new to piped engines, not sure how to secure the blue rubber coupler (about 2" long) to the to the alum header. It came loose on 5th test flight yesterday, pipe assy moved back about an inch in flight. I used the zip ties that came with the Dave Brown pipe mount kit and cinched them (one over header, one over front of pipe) as well as I could. Problem may be smooth surface on header. Should the header surface be roughed with garnet paper or something, or use high-temp silicone to glue the rubber part to the header? Or some other solution?

Offline Peter Nevai

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 975
    • C3EL
Re: How to secure coupler between pipe and header
« Reply #1 on: February 05, 2018, 09:13:15 PM »
If all that is supporting the pipe in place is the connector tube then It will sooner or later work it's way off. If you have the pipe secured in place then it should never be able to move a whole inch. Besides if the pipe moves in flight then the tune goes right out the window. You should have the pipe support / hanger that the pipe can be secured to when the right length is dialed in.
Words Spoken by the first human to set foot on Mars... "Now What?"

Offline Balsa Butcher

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2357
  • High Desert Flier
Re: How to secure coupler between pipe and header
« Reply #2 on: February 05, 2018, 09:21:45 PM »
Hi Mike. I don't remember how small the du-bro zip ties are I use thin ones that are sold by Ace Hardware stores or Home Depot etc. Hint: Get the ones that are labeled "for outdoor use". I think they are the black ones. They can be cinched up tighter than the whitish ones. Use two on each end, one won't cut it. I have a cool little tool that tightens them however needle nose pliers or even diagonal pliers can be used. Don't just pull, roll them while grasping the tie till they are really, really tight. Roughing up the surface or using silicon should not be necessary. Good Luck.
Pete Cunha
Sacramento CA.
AMA 57499

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #3 on: February 05, 2018, 09:56:05 PM »
Thanks guys. I will get more zip ties and try again. There is nothing mechanically blocking the pipe from moving away from the motor (probably a lot of push from the exhaust stream) so I may see if I can engineer something if the problem persists. This is a PA40UL. Anyone use small metal hose clamps? I  know they weigh more than zip ties but probably a negligible factor given the 2.5 oz of lead in nose to balance the model (Oriental Plus with enlarged tail).

Offline RandySmith

  • Administrator
  • Trade Count: (0)
  • Admiral
  • *****
  • Posts: 13747
  • Welcome to the Stunt Hanger.
    • Aero Products
Re: How to secure coupler between pipe and header
« Reply #4 on: February 05, 2018, 11:06:28 PM »
Thanks guys. I will get more zip ties and try again. There is nothing mechanically blocking the pipe from moving away from the motor (probably a lot of push from the exhaust stream) so I may see if I can engineer something if the problem persists. This is a PA40UL. Anyone use small metal hose clamps? I  know they weigh more than zip ties but probably a negligible factor given the 2.5 oz of lead in nose to balance the model (Oriental Plus with enlarged tail).

The pipe mount  should hold the pipe from moving, I use a pieces of fuel tubing cut short and thread the zip tie that goes thru the  pipe mount, and around the pipe, it holds better than the hard tie, and vibration proofs, also when you  slide the coupler over the  header  or pipe, clean ALL  oil from it, use  spit, or soapy water  to lube it ti slide it into place, the water will dry out and it will not slip, if you use  oil , or  have oil on them  the tubing will slip

Randy

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #5 on: February 06, 2018, 04:53:26 PM »
Thanks Randy, I like the idea of fuel tubing on the tie that holds the body of the pipe. I will implement all these suggestions and try again this weekend. Our California weather is, unfortunately, forecast to be warm and clear for next 10 days.

Offline Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13716
Re: How to secure coupler between pipe and header
« Reply #6 on: February 06, 2018, 09:41:30 PM »
Being new to piped engines, not sure how to secure the blue rubber coupler (about 2" long) to the to the alum header. It came loose on 5th test flight yesterday, pipe assy moved back about an inch in flight. I used the zip ties that came with the Dave Brown pipe mount kit and cinched them (one over header, one over front of pipe) as well as I could. Problem may be smooth surface on header. Should the header surface be roughed with garnet paper or something, or use high-temp silicone to glue the rubber part to the header? Or some other solution?

   Rough up the header with about 60 grist sandpaper, and clean the inside of the coupler and the outside of the header with acetone or lacquer thinner until it is completely dry and oil-free. Slide it on about 3/4", and use two medium zip ties in opposite directions (wrap one around from left to right, and the other from right to left). Align the ratchet part so they aren't in a line with each other. Tighten them up with a ty-rap tool or pliers, rotating the pliers up against the ratchet to pull it really tight. Cut off the ends. Once you run it once, it will practically be welded to the header and sometimes you have to cut them off.

   For the pipe side you have to be more careful. All of my pipes have had the front end collapse, even with the insert in there. It will soften up and squeeze the pipe smaller immediately behind the insert. I cut off the bad part, filed about a 1.5" section of aluminum header pipe to that it would slip-fit inside the pipe for about an inch, cleaned everything with lacquer thinner, the glued the tube inside the pipe with J-B Weld. Then you treat this aluminum pipe like the header.

    Brett

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #7 on: February 06, 2018, 10:27:17 PM »
Again, thanks everybody. Bob's Yer Uncle reports seeing header pipes really gnarled with Dremel tool or whatever (when not being used to improve the timing on motors) to really grab the rubber coupler. Since it may tend to weld itself to the header anyway, is use of a high temp silicone sealer a reasonable approach to sealing the slippery end? Plus zip ties of course. The flange on the front end of the pipe seems more likely to not move so probably less of an issue than the header-to-coupler joint. Add Randy's technique of securing the body of the pipe and all should be good to go.

« Last Edit: February 08, 2018, 07:38:44 PM by RandySmith »

Online Dave_Trible

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6132
Re: How to secure coupler between pipe and header
« Reply #8 on: February 08, 2018, 11:20:17 AM »
 I could never get any cable ties to hold the pipe on the header side of my RO Jett .76s.  Too much pressure.  I’ve blown several completely off the airplane.  I use a small  heater hose style auto hose clamp.  It weighs a little more but stays on.  I also use a double walled high temp silicone heater hose from OReillys for a coupler.  It’s like $20 a foot but lasts a long time.

Dave
AMA 20934
FAA Certificate FA3ATY4T94

Offline Steve Helmick

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 9920
Re: How to secure coupler between pipe and header
« Reply #9 on: February 08, 2018, 03:59:36 PM »
Being new to piped engines, not sure how to secure the blue rubber coupler (about 2" long) to the to the alum header. It came loose on 5th test flight yesterday, pipe assy moved back about an inch in flight. I used the zip ties that came with the Dave Brown pipe mount kit and cinched them (one over header, one over front of pipe) as well as I could. Problem may be smooth surface on header. Should the header surface be roughed with garnet paper or something, or use high-temp silicone to glue the rubber part to the header? Or some other solution?

As I read this, it sounds like there is a DB pipe mount at the joint between header and pipe, and that's the only one? If so, that's incorrect. The (single) DB pipe mount should be back near or at the baffle in the pipe. The front of the pipe is  supported by the header & coupler tube.

I like Randy's suggestion to put the wire tie through silicon fuel tubing at the pipe mount. I hope I can remember to do that, next time I have the need to pull and reinstall the pipe of either of my piped planes...it's likely to be awhile.  D>K Steve 
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline RandySmith

  • Administrator
  • Trade Count: (0)
  • Admiral
  • *****
  • Posts: 13747
  • Welcome to the Stunt Hanger.
    • Aero Products
Re: How to secure coupler between pipe and header
« Reply #10 on: February 08, 2018, 07:39:06 PM »
Hi Mike

do not  use  silicone sealer, unless you are just using a tiny bit to glue the aluminum insert, and even that is NOT  needed, that will weld its self to the pipe.
If you do as I wrote and CLEAN the header, get ALL oil off of it, then use a small amount of spit or windex, and slide the silicone coupler over it, use 2 Zip ties, on the header side, cinched tight, it will  also weld itself  to the bare aluminum header, and will not come off.
The clean ALL the oil off of the pipe, use spit or windex, slide the coupler onto the pipe, make sure you put the  2 Zip ties on the pipe at/over the  Alum insert,  DO NOT put one behind the alum insert, it will then crush the pipe.
I have had pipes in my planes since 1980s and setup so many more, i have  NEVER had a pipe come off.
The only times I had seen a pipe blown off  it was  NOT done lie this.
Be careful  silicone is prone  to  nick easy,. and this will cause a failure or blow out of the coupler.
I have dual layer  thin  silicone hi temp coupler with cloth matrix in between for sale also that is much better than the  old stuff we used.
Together with the  technique I wrote earlier  with using fuel tubing around the  pipe mount zip tie  will make  all of this a  NO Issue.
One more thing, at the top of the pipe mount where the pipe sits, do not use the  foam pad, I cut a 1 inch square or thin towel  and sit it the for the pipe to sit one

Regards
Randy

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #11 on: February 08, 2018, 08:39:53 PM »
Steve, the DB pipe mount bracket is at rear of pipe approximately at baffle location. The problem I am having is at the front where pipe and header are joined.

With all these ideas I am confident I can put together a mount that will stay put until I decide I need to move it for adjustment. Per Randy's pipe length chart I am starting with 17" glow plug to baffle on this PA40UL.

Randy, if I want to order some coupler hose from you, what do I ask for? The one supplied with my pipe mount stuff is only about 1.5" long, seems too short for proper sealing and allowing for some length adjusting. Is it listed on your web site?

Thanks everyone.

Offline RandySmith

  • Administrator
  • Trade Count: (0)
  • Admiral
  • *****
  • Posts: 13747
  • Welcome to the Stunt Hanger.
    • Aero Products
Re: How to secure coupler between pipe and header
« Reply #12 on: February 08, 2018, 09:34:41 PM »
Steve, the DB pipe mount bracket is at rear of pipe approximately at baffle location. The problem I am having is at the front where pipe and header are joined.

With all these ideas I am confident I can put together a mount that will stay put until I decide I need to move it for adjustment. Per Randy's pipe length chart I am starting with 17" glow plug to baffle on this PA40UL.

Randy, if I want to order some coupler hose from you, what do I ask for? The one supplied with my pipe mount stuff is only about 1.5" long, seems too short for proper sealing and allowing for some length adjusting. Is it listed on your web site?

Thanks everyone.

Hi  just call me  678 407 9376  or  email, you can buy a foot or more long piece, you should  only use it as long as it has to be, 4 inch long is  OK , you do not want to use a long piece  as it is heavy and needs support,  You can also  Email and order  in ton me  at  Randyaero@msn.com  just ask for  silicone pipe coupler material, we use  5/8 inch, this is  tight going onto the  header, and  that helps it to  stop slipping

regards
Randy

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #13 on: February 11, 2018, 07:35:26 PM »
Success, at least so far. With two cranked-down zip ties in opposite directions on header and two on pipe , oil-free surfaces, and fuel tubing on the rear pipe mount, all held together on the one test flight I was able to get in today before glow igniter gave up the ghost. Thanks for all the suggestions from everyone!

Offline Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13716
Re: How to secure coupler between pipe and header
« Reply #14 on: February 11, 2018, 07:49:19 PM »
Success, at least so far. With two cranked-down zip ties in opposite directions on header and two on pipe , oil-free surfaces, and fuel tubing on the rear pipe mount, all held together on the one test flight I was able to get in today before glow igniter gave up the ghost. Thanks for all the suggestions from everyone!

     Do it right and there is no issue. Frequently, I forget and leave the pipe mount loose (since the fuselage will hold it) and the pipe doesn't go anywhere. I have never had the coupler slip, the only issue I have ever had is the pipe melting and collapsing in the front.

     Brett

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #15 on: February 11, 2018, 08:46:00 PM »
So at least I still have a melting and collapsing pipe to look forward to.  The learning curve is just so darned steep with this 1980's technology.

Offline Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13716
Re: How to secure coupler between pipe and header
« Reply #16 on: February 11, 2018, 09:55:48 PM »
So at least I still have a melting and collapsing pipe to look forward to.  The learning curve is just so darned steep with this 1980's technology.

       At least you are willing to try it. We still have legions of people still trying to do it with 50's technology.

  What engine are we talking about? Aside from some very early issues where we were running the engines completely peaked out, we never had much problem with pipe collapsing until we got to 61s.

    Brett

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #17 on: February 11, 2018, 10:07:23 PM »
This is a PA40UL, running APC 11.5 x 4 prop. I have CF 3-blades from Brian Eather but don't want to risk them on the pavement at our field. Motor got 2 hours of break-in on stand, now has about another 30 minutes in the air so still pretty tight. Started literally on first flip on test stand, then about 10 more during break-in. I am still figuring out how to reliably start it inverted in the model with it on its wheels. Need to get a filter or some stocking fabric on it.

Offline Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13716
Re: How to secure coupler between pipe and header
« Reply #18 on: February 11, 2018, 11:51:01 PM »
This is a PA40UL, running APC 11.5 x 4 prop. I have CF 3-blades from Brian Eather but don't want to risk them on the pavement at our field. Motor got 2 hours of break-in on stand, now has about another 30 minutes in the air so still pretty tight. Started literally on first flip on test stand, then about 10 more during break-in. I am still figuring out how to reliably start it inverted in the model with it on its wheels. Need to get a filter or some stocking fabric on it.

     Burp - have someone hold the airplane inverted, dribble fuel into the venturi, tilt nose up, rock prop back and forth, rotate airplane wings vertical, rock some more, until it feels "loose". Then hold airplane inverted, attach battery and back-bump up against compression. It may spit and pop the first time, repeat until you get a full speedup and then rundown.I habitually wait do this three times - fuel in venturi, back-bump, speed up and run down. When done, repeat back-bumps until you just get pops - this ensures that you have gotten all the stray fuel out of the engine.

    Cold - pull through compression  3 times with your finger over the venturi, remove finger and flip through immediately a few times to suck raw fuel into engine and aerate the charge, attach battery, back-bump up against compression. If it doesn't go, repeat, the problem is not enough fuel.

     Hot - pull through compression once, attach battery, back-bump. If it bursts but then quits (meaning you had enough choke but not enough fuel in the line), then you might have an issue because of shrinky piston syndrome. If so, then remove the battery, flip through compression forward about 20 times, attach battery, back-bump up against compression.

"lukewarm"  - you have to choke it a few pulls,  which may cause shrinky piston syndrome, because you have to choke it a few times, and cold fuel on the underside of the piston crown will shrink it. Hot, you don't want to choke it to the point you get raw fuel in the engine, just enough to make sure the fuel is in the line. This is the most difficult condition to get it started, solution is as above, remove the battery and flip it through forward a bunch of times.

    DO NOT ever flip it through compression with the battery attached like a McCoy or ST, in either direction, unless you want a ride in an ambulance or enjoy the sight of blood. It's not at all nasty to handle but you just don't want to do that, ever, to one of these engines. Back-bump by winding it forward against compression, the vigorously flinging it backwards, but DO NOT flip it through compression, your finger should be far away from it when it hits compression and fires.

   With the APC, feel free to sand the TE of the prop flat with 240 grit sandpaper until you can safely flip it forward through compression (with the BATTERY OFF) to aerate the charge. Unless, again, you enjoy the sight of blood, in which case you can leave it as it comes, sharp as a straight razor with a wire edge.

    Brett

Offline RandySmith

  • Administrator
  • Trade Count: (0)
  • Admiral
  • *****
  • Posts: 13747
  • Welcome to the Stunt Hanger.
    • Aero Products
Re: How to secure coupler between pipe and header
« Reply #19 on: February 12, 2018, 01:42:31 AM »
Hi Mike

To protect your fingers and props, get a piece of heater hose from an Auto Parts  store that fits over your finger, Do Not use a Chicken Stick, or  glove, The hose will protect you from cuts  or breaks, and you will  not shatter  props like you would with a Chicken stick, that is the safest way to  start motors

Randy

Offline Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 13716
Re: How to secure coupler between pipe and header
« Reply #20 on: February 12, 2018, 10:52:10 AM »
To protect your fingers and props, get a piece of heater hose from an Auto Parts  store that fits over your finger, Do Not use a Chicken Stick, or  glove, The hose will protect you from cuts  or breaks, and you will  not shatter  props like you would with a Chicken stick, that is the safest way to  start motors

    I agree, but at this point, if I started putting things on my finger, I would probably have an accident after doing it the other way 10,000 times.

    The other thing I see all the time with chicken sticks and lengths of tubing, etc, is that people just *flog* the thing, I mean, taking a swing and hitting  the prop like you are trying to chop wood. I usually give mine a pretty good twist but most of the time you can get it to start just fine with a light twist backwards with your fingers on the tip of the spinner. You just have to sling it up against compression backwards. Hitting it hard doesn't seem to raise the odds of a start, if anything it makes it less likely to start.

     These aren't McCoy Series 21s where you can flip it forwards through compression twice with a good flip, these are extremely well-fit engines that will start as soon as you have the fuel and air in the ballpark. The biggest problem I have ever had was with them starting *without the battery* during casual handling -  not failing to start when you want it to.

       Brett

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #21 on: February 12, 2018, 11:22:46 AM »
Brett and Randy, thanks so much for the tutorial. I see I have been doing it wrong, this isn't an LA46. I am going to print this and keep it in my flight box. I have always sanded the TE of APC props; saw a video of someone slicing a tomato with one and that drove the point home.

Hopefully I will learn to be one of those guys that starts their piped engines with one quick back-flip of the spinner, something that always leaves me in awe. I have heard the stories of PA engines starting spontaneously when the igniter is attached, so am wary of that.

I hand-propped the Continental A-65 in my Taylorcraft for the 15 years I flew it, still have both arms and one head. That is a skill that must be practiced with great precision and unfailing routine, plus proper pre-check for mags, fuel, etc. Requires a few pulls through till engine sounds squishy, then its mags on, throttle cracked, tail tied down, and a mighty swing. The leg kick is to get you moving back out of the prop arc in case you slip.

Offline Mike Scholtes

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1192
Re: How to secure coupler between pipe and header
« Reply #22 on: February 12, 2018, 03:56:53 PM »
While we're at it, where do you recommend positioning the prop for a right-handed person? Where in the prop arc should the prop blade you are flipping hit reverse-rotation compression, the "bounce back" point? I have never been one to whack or swat the prop with anything, rather a solid contact with blade at start of flip motion. Or is better to use left hand to flip in the reverse direction, which may be a more natural biomechanical motion? Wish I had watched David and the other guys more carefully. I will now.


Advertise Here
Tags:
 


Advertise Here