Not being content with "having my way" with the recent Oriental ARF, I recently completed a Cardinal for Big Art.  Again, there are LOTS of Cardinals out there built pretty much right out of the box, and people are flying them well.  The folks at Brodak are doing a GREAT JOB with this and the rest of the ARF/ARC/Kit line-up.  But once again "I never ever do anything nice & easy...!"  Anyone who read along with the Oriental build notes will recognize that I did pretty much the same things to this Cardinal.

Big Art picked up this kit at Toledo, inspection showed all parts in great condition, aside from the usual ARF-wrinkles.  Inspection of the wing indicated a warp.  So it was wrestled back into position while shrinking the covering.  Everything else tightened up without much grief.

Biggest set of mods involved the control system.  The bellcrank is already reversed (up-line in front - whoo hoo Brodak!) and the remaining control system mods are:

* Added bearings to restrain the flap and elevator horns
* CA type hinges cut in half to reduce their stiffness
* Moneycote hinge gap seals added to flaps & elevator.
* Outer 5" of flaps cut-off and set-up as trim tabs with horns & quick links.
* Cut-into wing to move flap pushrod from innermost hole to middle output of bellcrank.  This then runs to the outermost hole in flap.
* Installed SECOND pushrod in outermost bellcrank hole, running to outermost hole on elevator horn.

My biggest knock on the two Brodak ARF's I have built is that the instructions are a little vague - I was not really sure WHAT the control ratios were SUPPOSED to be, so I made them what I thought they should be.  The resulting control system has a 2:3 ratio flap to elevator movement.  The cut-down flaps avoid the shed vortex at the wing tips to keep the control loads manageable.  (i.e, it ADDS corner)

Last, and probably most important mod was to the ARF had a rather sharp leading edge - this in my experience is a bad idea.  I removed a 3/4" wide strip of covering rounded it off, and recovered it with a chrome moneycote "de-icing boot"!

Again, not leaving well-enough alone, I routed out the fuselage to "pocket" the tank; about 1/2" deep to the inner doubler.  Then I added a 3/16" wedge to kick the outer corner of the tank out - to help generate a clean engine cut-off.

Since this bird will fly most of its flights off grass I substituted 2.5" Dave Brown foam wheels in place of the 1.75"(?) foam wheels that came with the kit.  Remarkably the larger wheels easily fit within the slick wheel-pants, once the hole in the bottoms were opened up a little.  I trial fitted 2.75" wheels and could have made them work if I had to.

Big Art intended to fly this with a Brodak 40, so he made up some custom aluminum mounting plates and affixed them in place of the universal mount clamping plates supplied with the kit.

Test flight was last Saturday, but that will wait for the next post...

Bob R:
I think mine has too much tip weight too - even though it has none added!  I am flying on .015 x 63' lines, are you flying the 46 on 018's? that might be enough to make a difference.  As for the rest of the Day 1 test flight experience:

In anticipation of a great test flight the Cardinal was fitted with a "veteran" Brodak 40 that has proved itself numerous occasions on another profile. So naturally the darned thing put up a big fight until it finally started.  Got airborne and the engine went rich.  Actually meandering between rich and REALLY rich.   Could not do much of anything, but did get it inverted and confirmed the tank was in about the right position (might have to raise it a little).  At the end of the tank the engine leaped to dead lean for about 10 laps before I shut it off in a loop.

Flight 2 starting was a-kin to flight 1.  When we finally got it going the engine went nearly dead lean as soon as it got airborne.  Managed to do a couple loops and lazy eights, basically confirming that the wing looked fairly level and suspected too much tip weight.  However at that flight speed trim problems are masked.  Engine did not sag-out but it was not running very well! 
   
Started checking this and that, messed around with the fuel line routing, discovered the in-line filter was installed backward, but no real smoking gun for the goofy engine runs. 

After battling it again on the 3rd start, I got mad & swapped plugs.  Started the 2nd flip - problem solved, right?  WRONG!  Big Art was still wrestling with it to get a needle setting, and it came off the ground a little fast but definitely better than flight 2 and flyable.  Indeed, was in the midst of doing a complete pattern when the engine burped out of fuel in the VERTICAL eight! 

Finally decided THAT was enough, that there MUST be something wrong, and since everything else was the same, the problem must be with the fuel tank - the only "new" part in the system.  Sho'nuff, discovered a MAJOR
leak along the top of the wedge at the back.  Dummy, (rather, dumb me!) should have leak-checked (and not just inspected) the tank BEFORE installing! 


MORAL OF THE STORY: The engine was TRYING to tell us something was wrong, but we just kept pushing it and forcing it to run.  Worse, because the engine was a PROVEN COMMODITY of countless successful flights on the preceding profile, we should have been even MORE suspect if it did not fire right up and run right.  BTW if you are keeping score Big Art & I total a combine 100+ years modeling experience.  Proves once again that experience is no match for STOOPID - this ain't rocket science folks! 


Oh, BTW, the Cardinal really looks like a winner.  Got a great corner and the control efforts feel spot-on.  Think I might try moving the CG forward a twitch, but even as is it flattens out very well coming out of a corner - so it is not too far off.  Also might have to add INBOARD tip weight as there is none to remove from the other wing - NEVER had this happen before!

Tank is fixed, bird is ready to try again...

Haven't heard of any others with this issue but I had to hollow the outboard wing tip of my Cardinal to get the tip weight down to a reasionable level. Even left the cover and screw off the weight box, just covered with a piece of tape.

Built it for a ST 46 test bed and used stock controls but did increase the elevator throw, pretty good flying airplane.

Mine wasn't quite that bad, but I have no tip weight at all.

Steve:
Before I started the build I did a quick search here on StuntHanger and did not see (or managed to miss) anybody posting about excess tip weight.  While I was building this thing it seemed quite heavy on that side, but... 

First couple flights were difficult to pass too harsh a judgement on it due to the fuel tank woes - but it looked like it was hinging due to excess tip weight to me.  Bob's experence suggests that heavier lines would not make up the difference either.  Usually too much is a bother but not a barrier, but too little will make it challenging to fly!  My guess is the pre-weight would have probably been right except for the side-mounted profile engine.

No comment on the TF's... I get into enough trouble on my own!   

Hi Dennis, Glad to hear that your Cardinal is shaping up! I once had a terribly hard time getting my B-40 to perform with any degree of dependability. I thought that I had it right then I had to go and "fix" my tank location and thus needed another six weeks to unfix my fix! What finally did the trick for me was to measure the ID of the venturi orifice. Mine exceeded .300! I rumaged through my stash of brass tubing and found a piece of stock with an ID of .270. Bingo! All it took was a short piece of about 3/16" to neck the .300 down and that engine has been running sweet eversince!

The tank by the way is a double clunk Sullivan plastic job with the extra clunk going to the univent which is about 3/16" shorter than the fuel feed line.

Just for your information.

PS It was a great privilege to spend some time with your Dad at the Brodak event. I am glad he came by.

Phil Spillman

QUESTION: with the clunker do you center the tank on the engine or is it a tad above center?  When I cut the tank pocket on this one I made it large enough for  DuBro clunk, but only if it is centered on the engine...

Hi Dennis,

The "trick" with the clink uniflow when you cannot move the tank is to twist the cap.  Raise the uniflow inlet above the fuel feed and it works like moving the tank up.  Vice versa........  this was told to me by Bob Hunt and it has always worked for me.

Bill <><

Dennis
I have done the same modifications on two Cardinals I didn’t change the bell crank I used a taller 1 1/4 control horn to slow the controls and made the elevator move more then the flaps. But what I’m really proud of is this pin that your MOM gave to me years ago.
Willis

I have one too. Thank you Claus Makis(sp?) Hey guys. Went flying with Dennis, Arch, and Large Art today. We flew the heck out of the Cardinal. The B40 is comming back in, Big and I tore it down to measure it because it ran so nice, so it needed to re-seat. The plane is very nice to fly and I had a great time. I also flew Dennis's Super Clown which has a screaming Enya 30 on it. What a ball. I also have to comment on his Oriental with LA40. This engine is almost impossible to dis. It is getting stronger every run and is just doscile. It's swinging a 11x6 Powerpoint and pulling the heck out of that little stunter. The only complaint I had was I got covered with bean oil. Smells good but it is sticky.....

Hi Dennis,

The uniflow set up in my clunks are what Billy and Bob showed me.  the uniflow is actually attached to the feed line.  Similar to a metal tank set up.  It all swings together, just two pieces of 1/8" copper tube wrapped and soldered.  Only one "Clunk pickup" on the end.

Hi Dennis,

Using the three hole stopper, one is the overflow, one for uniflow, and one for feed.  The overflow tube bent in a "U" to the top, and about 1 1/4" tubes to go through the stopper for the other two. 

The "connection" of the tubes ends up looking like a "Y" (sorta) and those tubes are probably 3/4"-1" long, wrapped/soldered in the middle.  The feed line is the straight tube at the connector, and the uniflow is th bent one.  Both lines get a piece of Prather Pink from the stopper tubes to the connector, and the feed gets another piece of "PP" to the clunk.

I try to set the feed line pretty horizontal initially.  The uniflow line will rise above or move under the feed line (sorta).

Does this make sense?  I will try to take one apart tomorrow and photograph it if you like. (or just "make" another one! LOL!!)