What can be done to the planes and engines that are to raced at the Brodak Foxberg event? Things like landing gear, adjustable leadouts etc. etc. come to mind.  What can be done to the engines to improve their performance and still be within the rules?

       There is some interest in Foxberg from our club members for the 2014 Brodak contest.

                                                                                               Tia,

                                                                                               Frank
       

That would be best  asked  by the Contest director  or each  separate contests, some have different rules.

Randy

Frank,
I am not an engine tuner but the Fox 35 has a few things that can be done to make them run more consistent, these are not modifications more like blueprinting. First, break it in slowly with at least 25% oil most of it should be Castor.
 
After break-in there are a couple of things to check on the Fox 35. The case and cylinder on the Fox 35 is very thin (that's the price for light weight) and susceptible to warps and twists that can cause binding.

Take the plug out and remove the backplate, then put some after run oil in the motor and turn it over. Check that the con rod moves smoothly on the piston wrist pin and crank pin. As you turn the motor over it should be smooth with no binds. If you feel any binding loosen the three back head bolts and check again. If it is smooth remove the head and take a No. 30 drill and run it through all the holes from the fin side. This gives just enough room to allow the head to pull down smooth with no binds (use a cross tighten pattern on the head bolts, 1/8 turn at a time). Check the end of the crank pin for smoothness, some of the crankpins have a little nub or roughness that should be smoothed down, you may need to pull the crank out to do this. Next put the backplate on and again tighten slowly, checking for binding as you turn the motor over. If you find a bind as you get to the final tighten take a No. 29 drill and run it through the holes in the backplate then retighten. Once it's smooth you should be good to go.

One other thing that I found can cause binding is switching out the Fox standard Philips bolts for socket heads. Seems the head on the socket head bolts is just a few thousands bigger diameter than the Philips bolts and as you pull them down can rub against side of the relief in the head where the bolts seat. So if you've done the hole enlargement and it still binds and you change the bolts change them back and see if that frees it up.

Make sure the motor mounts are straight and use the cross grain balsa between the mounts (ala Super Tiger 60 style mount). If you use aluminum pads (or hard composite pads) put 1/64" plywood shims under the motor to provide "crush" space to allow for the very slight relief angle on the Fox mount case, here again as you tighten the motor into the mounts turn the motor over with the plug out and check for binding. If the mount bolts are not straight or centered you may need to run a No. 29 or 30 drill through the mounts to give room to for the bolts.

Lastly, make sure the NVA is sealed where it goes into the venturi (I use silicon high temp sealer). With the standard Fox NVA put a short piece of fuel tube over the threads between the body and the index click wheel.

Best,        DennisT

Lapping piston by someone who has the feel. Same with front bushing, so that when the crank is given a hard twist by thumb and forefinger it spins free. 40th Anniversary I hear has the best potential output because the liner is tapered with a pinch. This liner/piston often needs lapping (by someone with the feel) to assist break in and achieve optimum clearance. There's issues about head tightening, back plate tightening, as have been described. Easy to distort the case which will distort the liner which will inhibit full power. Cheat on fuel capacity. Put nitro in the bottom of the bulb.  

                          Dennis, the long and the short of it is that lapping the piston liner in is not an accepted procedure as your to fly the Fox out of the box. While you may feel that this is accepted in terms that your not modifying the engine, you indeed are doing things to the engine which by the rules is not acceptable. The gray area here is that if one was to dismantle the engine you probably wouldn't be able to tell if you did this. A trained eye can tell if the liner was also trued and flattend on the top end of the liner and those who fly are well aware of who is doing what to the engines.  The engine is not be modified in anyway and this generally isn't contested at Brodak's.It does indeed raise an eyebrow or two as two what really may be going on with some of the engines. In the 3 times I've had the pleasure to race at Brodak's, I haven't witnessed a single engine dismantled.  The only modifications that your allowed is to change the needle valve assembly and Randy Smith needles are indeed correct and fit the regulations. The Fox has a worthless piece of cr@# for a needle valve and this one modification alone is well worth the enjoyment of running the Fox and the correctly regulated engine run.

There was one non Fox in the finals at Brodak. I don't believe they were ahead, but they were running very well until someone struck a match to their plane during a pit stop. So..... it kinda burned up. Coulda happened to any of us. As for the other two teams, Al and myself totally dominated the Philly contingent. (Only kidding. It was a great race. There were boo.boos on both sides and I guess we made fewer of them 'cause we won by 1 second!!)
 
 The moral is: It's all about 'the race'. So. Read the rules. Get your junk together. practice a bunch and get out there! The type of race we had at Brodak does not happen that often so when it does it's just smiles all around for everyone.  Cheers, Tom

PS  The plane we used has been raced many times. Same motor,tank and prop. Pretty sure it also won at Brodak 10 years or so ago. Not exactly 'high tech'.

Hi Frank, Yes it's me. We are still at it although, just like almost everywhere, there are fewer of us. I have not been doing a lot of r&d with the faster classes lately cause they are faster than I am these days. The Brodak events are very doable and fun. This year they broke it into sportsman and expert classes and I think that worked out very well. I was a little apprehensive about flying 3 up for 15 minutes in clown but found that I could still do it well and that felt good. We didn't win that one but were right in there.  The competition was excellent! Hats off to Roy and Louis! (we like to think of them as our students. Guess they learned too good!)   Tom