What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-8 rear baggage smoke tank?

Here's mine

Go here to see my installation. I still haven't finished the system FWF.

http://www.mykitlog.com/users/display_log.php?user=owens&project=236&category=4794&log=104019&row=234

FP29042010A000DD.jpg
 
Tank

The previous system looks a little difficult to service. I have my battery in back and a 6 gallon tank strapped to the floor. With oil it would be dofficult to lift onto the shelf and may be a bit heavy for the shelf. Pump is attached to tank. I take it out to service or when I don't need it. Hydraulic quick disconnects on supply and vent and a molex plug for electric. Been blowing smoke for 8 years.

Just had a new issue come up. I clean my nozzles at annual but noticed weak smoke. Found the AN fitting attached to the nozzle had coked up. Makes sense. It's exposed to the same heat as the nozzle.
 
Smoke oil tank aft on RV-8

Just curious why the aft location? It seems to me the RV-8 front cargo is the primo location of any of the RV models, for many reasons. It's closest to the center of gravity of the airplane. I notice no difference whether the tank is installed or not, full or empty. It's MUCH easier to fill, you don't have to move a seat and who knows what else to get at it, so it's more convenient and you'll be less likely to spill oil all over your airplane. The tank is much easier to remove if you just want it out of the airplane. Front cargo offers a much shorter and easier routing for the plumbing, you don't have to find a way to get around the main spar. And with a 35 to 40 pound tank, times 6 G's, that's a lot of weight to support, right above your elevator push pull tube.

Jim Gray
www.rmrairshows.com
 
panhandler1956 said:
Go here to see my installation. I still haven't finished the system FWF.

http://www.mykitlog.com/users/display_log.php?user=owens&project=236&category=4794&log=104019&row=234

FP29042010A000DD.jpg
Click to expand...

Serviceability aside, a remote fill on the fuse would work fine here. However, as others have mentioned, that is pretty far back and would absolutely be a CG nightmare. IF it were a fixed weight, well it could be compensated for in other ways. However, given that the weight will go from being there, to not being there, that would greatly impact the flying characteristics over the flight envelope in a short period of time.
FWD baggage has its issues, primarily with leaks, spills, and taking up valuable useful space. I understand the logic of getting it into an otherwise unusable space.. However, I do not like this solution.
 
Front smoke tank

I put mine in the well of the forward baggage 3 gallon tank works great. Pull it out in 3 min. quick connectors and oil and electric.
 
Kahuna said:
Serviceability aside, a remote fill on the fuse would work fine here. However, as others have mentioned, that is pretty far back and would absolutely be a CG nightmare. IF it were a fixed weight, well it could be compensated for in other ways. However, given that the weight will go from being there, to not being there, that would greatly impact the flying characteristics over the flight envelope in a short period of time.
FWD baggage has its issues, primarily with leaks, spills, and taking up valuable useful space. I understand the logic of getting it into an otherwise unusable space.. However, I do not like this solution.
Click to expand...

Kahuna,
Good points! I forgot to mention that I have an external filler port for this tank. My airplane runs right up against the fwd CG limit with just me in the airplane so it flies much better with the tank full. In my testing, it goes from flying great to good over the range between full and empty, which is definitely a consideration. The the other challenge I have with this location is draining it if I want to haul a larger passenger - I haven't solved this yet, just need to get it done.

You are correct, it's not the perfection solution, just another option.
 
Hi Jerry,

I reinforced the rear baggage area on the down side and fabricated brackets which allow for a removable setup of the smoke tank assembly. I will use quick connect fittings for the oil line, the breather line and the electronic connections to be able to remove the smoke tank if needed/ wanted. When the tank is removed, two aluminum angle strips will remain in the baggage area.
Only logical, but keep in mind that you will have to find a route for the oil pressure line from the rear area to the firewall. Mine goes through the bottom of the baggage area and then towards the front under the floor panels.
I have not setup a photo account on the internet, send me a pm if you want to see pictures of my setup.

Located the oil tank in the back for W&B setup when flying solo - which will be the time when I will use the smoke mostly.

Regards,
Duncan
 
panhandler1956 said:
Go here to see my installation. I still haven't finished the system FWF.

http://www.mykitlog.com/users/display_log.php?user=owens&project=236&category=4794&log=104019&row=234

FP29042010A000DD.jpg
Click to expand...


Agree with Kahuna's comments and have one more to add. Let's assume that this is a four gallon tank. Oil runs about 8 pounds per gallon. Assume the tank will weight about 5 pounds. That's 37 pounds and add 5 or 6 G's and you have a weight of 185-222 pounds resting on those two skinny longerons. And if they should give way, look what's directly below: your elevator control rod! :eek: I don't like this installation one bit!

Just my $.02
 
ronschreck said:
Agree with Kahuna's comments and have one more to add. Let's assume that this is a four gallon tank. Oil runs about 8 pounds per gallon. Assume the tank will weight about 5 pounds. That's 37 pounds and add 5 or 6 G's and you have a weight of 185-222 pounds resting on those two skinny longerons. And if they should give way, look what's directly below: your elevator control rod! :eek: I don't like this installation one bit!

Just my $.02
Click to expand...

Comments on CG location of this are certainly valid. This install creates a condition that needs to be managed prior to every flight. It is however a very manageable condition.

I looked at it and don't see any glaring structural issues. I decided to back up my gut with some engineering. I hesitate to be to critical of someone else's design work based on a photo. I can't see how the tank supports interface with the longerons, but assuming that load path is good I calculate a factor of safety of >30 for the load you suggest on the longerons based on longeron-to-skin rivet strength alone. That's better than most of the airframe. Hopefully the builder has transferred the load from the lateral tank supports to the longerons equally as well or he will not get to take advantage of the 30X factor of safety further down the line.
 
You must log in or register to reply here.
Back
Top