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  #11  
Old 10-11-2016, 04:37 AM
Ron B. Ron B. is offline
 
Join Date: Nov 2007
Location: Yarmouth, Nova Scotia
Posts: 2,097
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Tim, I flew in temps with mine that I needed the cold air vents wide open (not as hot as you I'm sure) but did not notice any heat at my feet. I did not go looking for leaking hot air but did not notice any either. Obviously you noticed this before going looking for the source?
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  #12  
Old 10-11-2016, 01:34 PM
TimO TimO is offline
 
Join Date: Feb 2005
Location: Wisconsin
Posts: 337
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Ron, I did notice the leaking air right away, although the doors appear flush and tight at least when I'm not flying. Can't see them when I am. The tell-all was when I pushed the heater knob forward to put more pressure on it (since I left about 1/8" cushion), the leakage goes much away. The catch is, the detents aren't strong enough to hold the knob in that hard. And, they aren't strong enough to hold the vent from closing when in mid travel now that it's cold. So I know right where the heat is coming from. Just have to fix it.

To reply to AussieFlyer...I see I missed replying. I think you could remove the SCAT for summer if you felt like it. You'd probably want to cap off the inlet
too. The thing is, I wouldn't be too keen about leaving the heat muff around the exhaust then. I don't know enough about the ramifications to be qualified to say anything one way or another, but, that would create an area in the heat muff that could get hot around the pipe. So you probably should then remove the heat muff too. That would make it much less convenient though. The idea is, as long as there is air flowing thru the muff it won't get too hot. So I'd either remove the whole heater system or just seal off the doors on the firewall.

Personally if you want a temporary fix, I'd try some aluminum tape over the heater vent door seams. It's cheap enough and you can just peel it off if you want heat. So if you find yourself visiting a cold destination, you can quickly undo your workaround.

Again, I'm not an expert and maybe the muff wouldn't overheat, but I can just see that as a potential area that the exhaust pipe would then be hotter.
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Tim Olson - CFI
RV-10 N104CD - Flying 2/2006 - 1200+ hours http://www.MyRV10.com
RV-14 N14YT - Flying 6/2016 - 150+ hours http://www.MyRV14.com
RV-10/14 Transition Training: http://www.RVCFI.com
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  #13  
Old 10-11-2016, 03:03 PM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 6,873
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Quote:
Originally Posted by TimO View Post
Ron, I did notice the leaking air right away, although the doors appear flush and tight at least when I'm not flying. Can't see them when I am. The tell-all was when I pushed the heater knob forward to put more pressure on it (since I left about 1/8" cushion), the leakage goes much away. The catch is, the detents aren't strong enough to hold the knob in that hard. And, they aren't strong enough to hold the vent from closing when in mid travel now that it's cold. So I know right where the heat is coming from. Just have to fix it.

To reply to AussieFlyer...I see I missed replying. I think you could remove the SCAT for summer if you felt like it. You'd probably want to cap off the inlet
too. The thing is, I wouldn't be too keen about leaving the heat muff around the exhaust then. I don't know enough about the ramifications to be qualified to say anything one way or another, but, that would create an area in the heat muff that could get hot around the pipe. So you probably should then remove the heat muff too. That would make it much less convenient though. The idea is, as long as there is air flowing thru the muff it won't get too hot. So I'd either remove the whole heater system or just seal off the doors on the firewall.

Personally if you want a temporary fix, I'd try some aluminum tape over the heater vent door seams. It's cheap enough and you can just peel it off if you want heat. So if you find yourself visiting a cold destination, you can quickly undo your workaround.

Again, I'm not an expert and maybe the muff wouldn't overheat, but I can just see that as a potential area that the exhaust pipe would then be hotter.
If you reconfigure the heat system, you MUST do it in a way that keeps air flowing through the heat muffs if you leave them installed.
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RV-6A (aka "Junkyard Special ")
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  #14  
Old 10-11-2016, 03:25 PM
KeithB KeithB is offline
 
Join Date: Mar 2014
Location: Granbury, TX
Posts: 93
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Tim:

Here are photos of the A-700 locking cables:





Vans "detented" cable on the left, "locking" on the right.
Shafts at mount measure 0.365" on Vans, 0.425" diameter on locking cable.
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RV-14A Builder - kit #136
N314KC - First flight Mar 8, 2017, Phase I compl Apr 3, 2017
RV-6A sold
Sport Pilot (weight-shift control) - Airborne XT912
Dues paid 12/2016

Last edited by KeithB : 10-12-2016 at 09:02 AM.
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  #15  
Old 10-12-2016, 07:26 AM
TimO TimO is offline
 
Join Date: Feb 2005
Location: Wisconsin
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Thanks Keith, great pics! Last night I kinked my cables and went flying. The kink was enough to keep the vent from creeping when I turned the heat on. But, the kink didn't help when I tried to keep the valve completely shut. Or it at least didn't help much.

I was on the fence on ordering cables until spring, because for the next 6 months I won't care if it leaks, but after seeing your photos they look nice enough that I'm going to just order them today. That way it's on my to-do list and I can get it done during the winter. That looks like a much better way to go.

Scott, thanks for commenting on the heat muff thing. That was what I was thinking, but you verified it. I think you could cause issues by not having airflow thru the muff.
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Tim Olson - CFI
RV-10 N104CD - Flying 2/2006 - 1200+ hours http://www.MyRV10.com
RV-14 N14YT - Flying 6/2016 - 150+ hours http://www.MyRV14.com
RV-10/14 Transition Training: http://www.RVCFI.com
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  #16  
Old 10-12-2016, 08:48 AM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Quote:
Originally Posted by TimO View Post
That was what I was thinking, but you verified it. I think you could cause issues by not having airflow thru the muff.
Yes, it can cause an extreme over heating of the pipe under the muff, and the muff itself. Depending on localized air flow, it might not be a problem, but it definitely can be.
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  #17  
Old 10-12-2016, 09:11 AM
GigAir GigAir is offline
 
Join Date: Apr 2013
Location: Gig Harbor, WA
Posts: 41
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Tim, THANK YOU, for continuing to do these "shakedown reports" on the RV-14a.
With a new model like this, there will be a myriad of little things, like this heater cable, that needs to be understood and finessed. Your willingness to articulate the issues and put them out there for discussion, is highly valuable for all of us, a few months behind you.

Greg Novotny
RV-14a N14ZP
fiberglass....everywhere
Gig Harbor, WA
Kailua-Kona, HI
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  #18  
Old 10-12-2016, 09:47 AM
BillL BillL is online now
 
Join Date: Sep 2007
Location: Central IL
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Quote:
Originally Posted by sibriggs View Post
The way to tighten a cable that is used for the heat flapper is to make a small (not to sharpe) bend in the cable. This will increase the friction on the wire inside the spiral wound core and stop wire inside the cable from sliding due to vibration.
Right! and that is the way McFarlane induces friction in their cables. Mine came that way with a tag NOT to straighten it. It has 4-5 sine wave wiggles in the casing. Maybe .040 displacement?
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  #19  
Old 11-05-2016, 05:10 PM
TimO TimO is offline
 
Join Date: Feb 2005
Location: Wisconsin
Posts: 337
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Keith, thanks again for the pics. I ordered those cables back when I made my last post, but hadn't yet put them in. A few more flights and depending on the heater vent position the valve was still creeping either closed or open, even with the kinked cable.

Today I decided to dedicate the day to swapping in the nicer A-700 cables. It was a very easy swap because other than the hole enlargement to the threaded end there really was no major difference. When I got done I finally had a flight where when I pushed the vents closed, I had a minimized heat leakage, and when you put them in a specific position they will stay there.
Very happy I upgraded the cables. Thanks for taking those pics for me and posting them.
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Tim Olson - CFI
RV-10 N104CD - Flying 2/2006 - 1200+ hours http://www.MyRV10.com
RV-14 N14YT - Flying 6/2016 - 150+ hours http://www.MyRV14.com
RV-10/14 Transition Training: http://www.RVCFI.com
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  #20  
Old 11-06-2016, 04:07 PM
KeithB KeithB is offline
 
Join Date: Mar 2014
Location: Granbury, TX
Posts: 93
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Tim - glad to hear the cables work as hoped. You don't mind the additional expense when it produces the desired results.

As an RV-14 "still under construction," I really appreciate the time you take to keep the rest of us up to date on tweaks you are making.
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Keith Brown

RV-14A Builder - kit #136
N314KC - First flight Mar 8, 2017, Phase I compl Apr 3, 2017
RV-6A sold
Sport Pilot (weight-shift control) - Airborne XT912
Dues paid 12/2016
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