Venus II does fly better than my 540T btw...and my 540T is excellent.

2 different beasts. The edge is better for 3d.

I know, earlier I had said I thought the Edge flew as well as the Venus, but the Venus has a slight edge on aerobatics, the Edge will hover though, the Venus only hovers in it's dreams...lol

Gents,

I'm currently assembling my Venus II and would appreciate some advice regarding fuel system setup.
I'm using OS-120AX with a Slimline Q Series muffler and since I moved the fuel tang aft to the CG I will be using a Perry pump.
Now do I still need to pressurize the tank from the muffler or will the pump is sufficient for the job?
Can anyone suggest a simple and efficient fuel lines setup for refueling and draining?

Thanks

Yoav

Perry advises against using muffler pressure with the regulated pump. Just vent the tank to the atmosphere.
I have the same setup (except with the stock muffler) and it took considerable fiddling to get it right but it's worked well since.

Here's the procedure I used to get it right...a little different from the instructions, but it works. I didn't invent it, but don't remember who posted it first.

Run the engine without the pump to get an approximate high-speed needle setting. Now hook up the pump. The setting should now be rich. If it isn't, increase the pump output (by turning the screw IN) until it is.
The mid-range will probably be rich. Run the engine and note the throttle position when it begins to go rich. Stop the engine and adjust the idle screw so the needle is just beginning to enter the jet at this point. I had to turn mine in considerably.
This is your new starting point and all your adjustments should be minor from here.
Good luck!

Yoav:
Here is a picture I posted of the fuel line hookups using a perry pump on an OS AX120. The post explains the details. Also if you look around the posts near this one, you will find other pictures and explainations of fueling.

http://www.rcuniverse.com/forum/fb.asp?m=7150042

Note the angled brass tubbing mounted in the side is the vent to the tank. it stays open. The vent needs to stay open to the air. When the plane is sitting on wheels, the brass tube points downward and extends into a bottle for easy overflow catch.
The black pug on the side is the filling line.

The midrange can be just slightly a little rich with a pump setup. To offset this i use 15% nitro and that really fixes the issue. However 10% works OK too, just 15% is better.

Codfish:
What plug are you using?

Strat2003

Thanks for your tip



Codfish,

Not sure if I get you right. Do you use 2 weighted clunks in the tank?
As far as I understand your setup, only one is needed and that is for engine feed. The other two can be identical (as the vent). I think this requires that fueling will alwas be done when the plane is not inverted (on its wheels).

Yoav

Yoav,

You are correct that you use two weighted clunks (I use a filtering clunk on the engine line). One for fill and the other for engine.
The plane must not be inverted when filling with this configuration.

Is this the behavior you desire?

So where does excess fuel go when tank is full? (vent line allows air only into the the tank, right?)

Ytell,

The vent line is just a simple tube it does not have a one way valve.
When the tank is full, the overflow comes through the vent line and out into your catch bottle!
You simply position a catch bottle under the angled brass tube during filling. A 12 oz bottle will just slide up over the tube, which holds the bottle still, ready to catch the overflow. It's the most conveinient system i have ever seen

The vent line is just a tube run to the top of the tank on one side of the tube, and the other side of the tube is the angled brass tube you see in the picture...

You may be wondering why the fuel does not pour out when you are inverted. It does not pour out because the tank is not pressurized as in a regular pressurized system. Also the angled brass tube is bent in such a way that when inverted, the end of the tube is above the fuel line. Pretty cool eh? My own design!

Make sense?

The fill and engine pickup are run to clunks in the tank. This is call a 3-line system.

Codfish,

From the picture you posted it looks as if the bended vent tube interferes with the engine cowling. Is it?
Would't it be better to install it a little more aft on the fusalage?

I'm starting to get the idea and it looks very good. Where do you want me to send the royalties?



Yoav

I’ve completed and maiden my Venus and it’s time for a report.
Over all I’m very pleased with the results. I used some tips I found in this thread regarding fuel system setup (thanks Codfish) and as can seen in the pictures below the result is a clean, efficient and light setup.
I put some efforts to make it as light as possible and the result us really good. No weights to compensate for a heavy muffler upfront, no pilot figure and even a small throttle servo. Fuel tank is close to the CG. Overall weight is a little less than 4 kg. The result is a great F3A plane which is joy to fly.

Yoav

ytell,
Can you please post a pic of motor with cowl from the right side please.
I am just starting my build with the same motor and Q Series muffler.
Regards
Gil

Here you are


Yoav

Thanks,
A bit of figuring to be done.
Gil

Hello All,

I have a Venus 2 with an OS 91FX for power. I was at the field over the weekend and realized I was bingo on 15% fuel, so I ran 30% heli fuel. Ran Great, I picked up about 800 rpm's. Besides the added cost of 30% is there any harm in running 30%?

The 91FX engine is designed for 5% to 20% nitro. In my opinion you are definitely putting the engine at risk for premature failure running at 30%. If you don't mind buying another engine, that is OK. It's the trade off you face. If you really want to know how it is affecting your engine use a infra red temp gauge and check the temp after a hard run. That will tell the truth. If you need more power and want to do it right, switch to a 120 AX. The Venus loves the 120AX.

Entered my first Pattern Contest and pick up first place in the Intermediate Class at the Western Canadian Pattern Championships. Venus powered by OS 120 AX

Congrats! ARTP47!

I thought i'd post some pictures of the Turbo-Jett muffler in a Venus II so you can see how well it fits.

These pics are of my Venus II which is slowly progressing. The engine is a Webra .91 and the muffler is the 91-1.20 sized Turbo-Jett.

Dubb can supply the muffler with adapter plates for different engines. This muffler also fits the 1.20AX.

The engine is angled approx 4 degrees down by rotating the supplied firewall drilling template 3mm (1/8") anti-clockwise.

Ziomarco,

I have been running the OS 1.20AX I have for over 2 1/2 years now on 30% heli fuel with no issues. There are multiple advantages to 30% nitro, the biggest of which is the fact the engine runs cooler. This is very beneficial in a cowled scenario. Also, the added oil content is better long term for the engine. What I would not recommend is over propping the engine trying to gain more performance that way, but picking up a few hundred RPM is no different than running a pipe. You wont have any problems running 30% fuel in any of today's glow motors as long as you stick with the recommended prop sizes.

Arch

Arch,

Really curious how a higher nitro content makes an engine run cooler. Can you explain that one to us?
Furthur more why would an engine manufacturer's specify a maximum nitro content?

Higher nitro essentially lowers the flash point of the engine. there are some other chemistry definitions, but essentially that is what it does. The engine runs cooler. Go do all the research you want on that. I'm sure one of the experts can explain it better, but after running OS engine for most of the last 20 years...these are my findings. I also know that in SW texas last summer if I ran 20% nitro I had overheating problems on my YS 1.70DZ. When I switched back to 30% the problem went away. One recommendation you will hear often is in a cowled engine scenario you can run higher nitro to make the engine run cooler.

I'm not saying OS doesnt say to run higher nitro, i simply answered the guys question that the engine will run fine on higher nitro. Manufactures specs are often recommendations. Doesn't mean they wont work with other things. Many Futaba servos specifically say 4.8v only, but they will all comfortably run on a 6V system. I think if you use a high quality fuel you wont have problems. You are much more likely to have engine problems by running 10% nitro on a cheap fuel whose oils are not up to par.

Arch

Higher nitro content helps an engine run cooler because your needle will be at a richer setting. Nitromethane is an oxidizer and although in it's raw form it has half the power of methanol it also takes half the oxygen to burn that methanol does so it works as a power increaser by helping combustion, but you also put more fuel through the engine.

Now as for why a manufacturer would give a suggested nitro range, that is much simpler, pre-ignition. Depending on compression ratio of the engine you might need to shim the head on a glow engine to use a hgher nitro fuel. I have yet to own an engine that would need shimmed on 30% but that is only my personal experience.