B40 hiccups cured , and then......

[roscoe]

Hi and thanks to the guys who replied to my first post. Alrighty, I  with help I must add, got acceptable stunt runs from my Brodak 40 by sleeving down the venturi. After trying a couple of clunk tank set-ups and many flights which were all "run-aways". Decided it must be the engine. So a friend made me a venturi insert and apart from a nice 4/2 break I 'm able to get a 6 min engine run using 4 oz's of fuel........then I landed on my toolbox.  I still feel like a total dufus!!!! . I should be able to fix the LE damage O.K. Current set-up as follows :11x5 bolly brown plastique prop, Thunderbolt R/C glowing plug. uniflow clunk tank / sintered brass clunk. Dinged -up Cardinal. Thanks again for the on-line  advice and suggestions.  Cheers Roscoe   

[Ron King]

Roscoe,

Is there a reason you are using a 4 ounce tank? The Cardinal has plenty of room for a bigger tank (I am using a 5 ounce GRW uniflow) and the Brodak 40 runs great with the stock venturi. I'm getting about 6:38 with 4.5 ounces of 10 percent fuel.

I'm using an APC 11.5 x 4, but your Bolly Clubman prop sounds fine, also.

Hope you get your plane repaired soon. I consider the Cardinal profile to be the "Gold Standard" for profiles and think you will really enjoy it. 

Ron

[roscoe]

Hi Ron, Just had it in my head that a 4oz tank was about the right size for a .40. I'm also flying a Tutor 2 with an LA 46 using a 6oz tank, (double clunk) . This is my favourite profile at the moment, I can live with the twisty tail feathers . So I'm trying to get the Cardinal to perform the same . With the improved engine run I will try some different props next. The local rabble at the flying field say I should put an LA 46 on the Cardinals nose and be done with it!  Ta for your input. Cheers Roscoe

[Ralph Wenzel (d)]

Hi,
I had a Cardinal set up with B.40 (stock venturi), 4 oz Tettra tank, running PowerMaster 10-22 fuel. Prop was a Rev-Up 12-5 cut to 10½". This combo ran like a top and delivered enough runtime for a pattern + about 3 laps; then 1 lean lap at the end and a clean cutoff. If you're getting significantly shorter runs, I would first suspect that the engine isn't fully broken in. Economy increases greatly over the first two hours (!) of running.

Second guess is that there may be quite a bit of fuel left in the tank when the engine quits. Have you tried filling the tank and then sucking the fuel out (through the feed line) with a graduated syringe? That may reveal the cause of the problem . . .

[Ron King]

Second guess is that there may be quite a bit of fuel left in the tank when the engine quits. Have you tried filling the tank and then sucking the fuel out (through the feed line) with a graduated syringe? That may reveal the cause of the problem . . .

This problem has popped up in several profile planes around here - not just the Cardinal. It first hit me in the overhead eight: the engine just cut suddenly. It picked right up and ran the rest of the flight, but it scared the p!$$ out of me and ruined my concentration. The next time it happened in the vertical of the clover, right after the second loop. The engine fired up again both times, but I knew there was something wrong somewhere. I knew I had enough fuel and blamed the glow plug. Switching to brand new plugs did NOT cure the problem. 

Several of the maneuvers we fly at the end of the pattern can load and unload the G's on the plane enough to slosh the (small amount) remaining fuel inside the tank. In full scale aviation, we call this "unporting". Guess we could call it the same in model aviation. When the fuel unports, it lets an air bubble go through instead of fuel and can cause a momentary burp - or a full shut down.

For my profile, the problem was finally solved by adding shims to the rear of the tank and angling it out slightly. Somewhere between 1/8" and 1/4" works well and gives you a very clean cut at the end of the flight. I'm now angling the tanks as best I can within my full fuselage ships, too. I understand some experts have been doing this for years, but I must have been hiding behind the door when they passed out this tip. 

If you want your profile to look better, inset the front of the tank instead. Works the same way.

I am now a much happier pilot. 

Ron

[Bill Little]

Putting that angle on the tank is a given. 

Some guys (I think Brett posted one of his tanks) make their own tanks with this "feature" already built in.

Bill <><

[Wynn Robins]

. The local rabble at the flying field say I should put an LA 46 on the Cardinals nose and be done with it! Ta for your input. Cheers Roscoe

and how many of the "local rabble" have as many problems as you do with engine runs?  hmmmm.....last time I saw......no one....

there is a lot to be said for taking advice from those around you with setups that work and using that advise to to your advantage......but keep up with the messing around you are doing....at least it gives you something to do rather then practise your flying....

HA...see ya in the weekend.......