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  #11  
Old 02-18-2017, 07:42 PM
BillSchlatterer BillSchlatterer is offline
 
Join Date: Jan 2005
Location: Arkansas
Posts: 449
Default To check/solenoid ... or not!

Most of the Bulldog Formation group uses Marvin's stuff and we like it a lot. The solenoid or check valve is something you really need to do just for belt and suspenders work. What can happen, believe it or not, when the tank is full (it's vented remember), you can end up with a siphoning action and find a quart or more of oil has been pulled back through the exhaust pipes and out onto the hangar floor. ( I know... I know ....but it just happens...)

Lots of head scratching on that one because we all "think" that if air or oil can't flow through the hose, you can't get a siphon effect. We all believe that but our hangar floors are proof to the contrary. So, the solenoid is real easy to add, (Normally closed),... wire it to your smoke switch and it's no pain and makes shut off clean and sure.

We have also noticed that this is particularly bad with nose draggers. Personally, I think that is because you can actually fill the tank to a point that is above the nozzle ports. Not so easy to do with a tail wheel plane and they don't seem to have the issue as bad... they still do but not as bad.

Nearly everyone we know that has flown a smoke system with others so that it is obvious when one doesn't shut off clean, now uses some kind of check valve or solenoid. I think Marvin is recommending the check valves today but I have the solenoid and it works great. The first didn't work so well and I found that in the closed position you could still blow air through it. I replaced it a couple of hundred hours ago and no problems since.

Now you may not believe any of this stuff about "siphoning" and inconsistent shut offs and that's fine..... but just saying. I don't have a great explanation but I've watched the 10 smokers in our group dribble and drip on many many occasions over the past three years flying a lot of smoking formation work.

The facts seem clear about why it shouldn't happen .... it's just the darn results that are confusing. I would put a check valve or solenoid on it just to be sure because it's easy .... and cheap insurance! My solenoid is on the tank/pump.

Absolutely have a controllable shut off valve (included I think) that you can get to while flying if at all possible. Start out with a 1/2 turn open and adjust until your belly is clean after a flight. In my 7, I have it just behind the passenger seat so I can lean it forward and adjust. I typically fly with it open 3/4 of a turn for normal use and 1 full turn for a lot of smoke .... and some belly oil !

Links to my install. https://kvisit.com/ai7Ee

PS... Smoke oil is way cheaper by the 55 gallon drum
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Last edited by BillSchlatterer : 02-18-2017 at 07:45 PM.
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  #12  
Old 02-18-2017, 07:49 PM
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Brantel Brantel is offline
 
Join Date: Mar 2006
Location: Newport, TN
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Default

Just installed Marvin's stuff in my plane since Christmas.

Works great. Started with the check valves and they appear to work great as well. I get crisp on and off.

Have not noticed any siphoning but mine is a TD. and maybe the check valves help?

I agree, Marvin's 55gal drum deal on his "SNAKE OIL" is the way to go if you have to pay for your own oil! Clear as water with absolutely no smell at all and freight cost is way less than expected and it produces great smoke!
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Last edited by Brantel : 02-18-2017 at 07:52 PM.
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  #13  
Old 02-22-2017, 12:05 PM
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wera710 wera710 is offline
 
Join Date: May 2008
Location: Pottstown PA
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Default Location

Not to hijack...ok, yes, to hijack...lol...but where are you all mounting the tank? I have had mine in the front baggage for years now and other than it being easy to service, remove as needed and install initially, I hate it. It's just too much weight up front.

The 8 just flies so much better with a bit less weight up front. I did not mount the tank in the rear baggage because I didn't feel like running a long hose at the time, but now I regret it. The nose is noticeably more heavy when the tank and pump are installed, and more so when full of oil.

So, what is your own experiences? Notice a difference with it up front?
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  #14  
Old 02-22-2017, 10:33 PM
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izzybear izzybear is offline
 
Join Date: Sep 2010
Location: Dallas, TX
Posts: 283
Default Interested in your engine / prop set up

So what engine and prop are you running? I am keeping things (relatively) light up front and understand the desire to keep things light. I am planning on a Whirlwind 200RV up front to save some weight...but have also heard about from people who don't like to load the rear to allow for more back seat passenger weight. I will be the first to admit I am not flying and all of my education is second hand.
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  #15  
Old 02-23-2017, 07:15 AM
flynwest flynwest is offline
 
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Location: Sacramento
Posts: 323
Default solenoid valve

It just cut the smoke off a little cleaner no dribbling smoke after you turn off the smoke.
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  #16  
Old 02-23-2017, 08:17 AM
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wera710 wera710 is offline
 
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Location: Pottstown PA
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Quote:
Originally Posted by izzybear View Post
So what engine and prop are you running?.
I have a O-360 180HP with a Hartzell CS prop. My battery is aft of the rear baggage. Under normal conditions the nose isn't overly heavy in pitch but the 8 definitely likes a little weight in the back with a metal CS prop. And from what I read about guys running out of pitch on approach (I do not with my config) it would seem to me metal or composite props would benefit from aft positioning of the Batt. It comes down to convenience vs nose heavy feel. On that note, I would never recommend putting a battery on the firewall if you are using an aluminum CS prop. In the 8, you really do benefit from having the battery aft. At any rate, I cannot give you pounds per Gee in pull with the forward baggage loaded with a full smoke tank. But it is a noticeable difference.

Losing 20 pounds of prop/governor might help this (approx 35 lbs for composite 55 lbs for metal). Not an option for me, as I already have the prop and have been flying on it for 600 hours. Still, my belief is that the aircraft would "feel" better with the tank in the rear baggage no matter which prop you run. A good example. If you end up doing formation training where you also might be doing some smoke runs during the same weekend, and find yourself in an aggressive extended trail session with relatively full fuel and a half full (or more) smoke tank up front, you will soon find the pitch (up) forces a bit of an unnecessary chore. Happens often, especially if the fuel truck doesn't listen to your instructions and instead, loads you up on fuel. Full tank, plus forward smoke tank = flying a truck vs mini-fighter. Another scenario: if you leave your smoke system in, and you tank up for a long trip, you soon find the nose heavy feel annoying until you can burn off a bit of fuel. Its not "bad" but its heavier than it need be.

And this is why I was asking where the majority of builders install their smoke system. I wanted feedback on what its like to fly with smoke system in the aft baggage. My guess is most folks do what I did. Take the easy route and stick it up front. But I have regretted it ever since. Except when its time to remove it. lol.

Flying acro with half tanks or less and a full smoke tank in the front is ok, but still, its more weight than ideal and you can feel it in the pitch force required vs no smoke sys up front. Its always the balance. Nose heavy Stability vs neutral CG Maneuverability. But in my limited experience, the 8 just flies better with less weight on the nose.
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