Ducted fan question
 

hello,

I have a ducted fan system like shown in the picture but an os max 65 i was wondering how you work the fuel tank as there is only one fuel plug that goes straight to the carborator....how do you pressurize the fuel tank to allow fuel to keep entering the carb. I know its a very beginner question but I am lost. Any help would greatly be appreciated.

http://jethangar.com/Ducted%20Fans/Turbax46.jpg

thanks,
brad

RE: Ducted fan question
 

You can pressurize the fuel tank with tuned pipe pressure or with pitot pressure.

For pitot pressure look here: http://www.jetmodelproducts.com/dynamax.htm

scroll down to pressure vent

RE: Ducted fan question
 

You will usually have 2 saddle tanks. They will be setup in series with pipe pressure being the force that gets the fuel to the carb.

RE: Ducted fan question
 

Your tuned pipe needs a pressure nipple like this:

http://www3.towerhobbies.com/cgi-bin...?&I=LXNFB2&P=7

You need to install it just aft of where the pipe reaches it's maximum diameter - just aft of the bend where it goes from an expanding tube to a constant diameter tube.

Best if you can find some way to build up the area that you drill & tap into so there's more than just the skin of the pipe holding it in.

If you are using a silicone coupler like the one in the picture you will probably have to replace it often. Be sure to clamp it down well or the pipe & header will slide apart.

RE: Ducted fan question
 

If you use the 2 saddle tank system, make sure all fuel lines are of "equal" length for both tanks, or you'll find one tank's fuel exhausting before the other (the tank with a shorter line will go first). Feed them both to a small hopper tank to ensure steady fuel flow with an adequate pressure system as indicated above. Best Regards,

Richie