Thoughts on building/flying the Brodak F-82?

Just guessing, balancing things out with a Black Widow and Golden Bee will be difficult.  From a flight performance point of view, it would be best to have the more powerful engine, being the Black Widow, inboard to help maintain line tension, but it is also desirable to have the outboard engine cut out first for the same reason.  This will be your problem because the Golden Bee will be more fuel efficient than the Black Widow and will run longer, the opposite to what you need.

I have built 3 of them to date and I like them a lot. I had two black widows on the 1st one which crashed coming out of a wingover when one engine quit. This is the problem with integral tanked bees. The gear is lacking and it collapses and I redesigned using my method. With two black widows, I needed some tail weight. I would also not limit the controls and use the outer hole in the bellcrank vs the inside which makes the controls a bit slow and not enough deflection. The other problem is the wing itself, it flexes a lot in between the two fuse's. I didn't do this on my last one and regret not sheeting the center. My 2nd one had two Golden Bee's.  My versions were not single ported Bee cylinders but dual so they offered good power.

         Main thing is to get two reliable engines that audibly sound equal which helps needle setting. Many seemed to be over concerned with starting one engine first , seeing that the outboard runs out first etc. I have never encountered that to be a issue ever. I always start the inboard first for safety reasons and then the outboard. I have twins from .020 - .40. Two black widows fly very well on 42' lines. I have used as much as 50' but the run time was too short. I have since switched to product engines.

       Here's a pic of my latest, I had it out this weekend. My flying partner and I fly these together as his has 2 TD's on it. He nipped my rudders because were were fooling around and got a bit too close so I need to paint the slugs of wood I put in there. I feel mine is more maneuverable. I shortened my fuse on the nose.

Hey Ken , are those #2 3/8 oz. tanks , what kind of run time do you get ? also where do you get your copper tubing for the tank fittings ? Thanks TJ

I was wondering how that plane flew after watching the change , good to hear it did well Ken .

TJ, my tanks are 1/2 oz. Perfect uses a brass tubing that usually splits on the seam and you can't see it internally. This is when you find out that Perfect tanks are not so perfect. Often they use a very small tubing which is also no good. That goes out in the trash. All tubing replaced with K&S 1/8" copper. I replumbed the tank for uniflow. Bottom vent only gets capped during flight. Most situations has proven to me that the uniflow pipe even though 1/8" is too large. I necked it down with a piece of 3/32" tubing that when cut with my tubing cutter closes the hole even further.

I haven't flown the model on uniflow to date as it got too cold here when I completed it. On the days that were worthy of flying, I had other models out. I never had a lot of luck converting a wedge tank to uniflow, it usually becomes problematic in the later part of the flight. I may even have to increase the tank capacity because I would like to fly the pattern using this one. If I choose to do so it will be plastic tanks.

I have flown my scratch built P-38 many times using both Golden Bees and Black Widows but never mixed the two.

I would invest in either another stock Golden Bee or Black widow. Just top off the interior to the circle engine last and you should be ok. Mine flew fine on one engine.



Good luck with your build.

Bob

Today I had the F-82 out. Since built, I had put it aside due to bad engine runs. I didn't follow my own advice and sheet the center section of this plane between the two fuse's. The inboard engine would run all day long at the correct setting. When the outboard engine was started, the plane gets into such a resonance that both needles go absolutely crazy. I used rubber bands to hold the needles which certainly worked but the runs would eventually go screaming lean no matter how rich it was in the beginning. I could see the covering in the center section of the wing vibrating and the engines were a blur. I tried so many options today I was going to grab it by the wing and toss it into the woods.

      I swapped engines and tried others but to no avail, the same thing kept happening. I wish I brought my 3 bladers one pusher and one tractor might have solved this by running opposed props.  I ended up with one 5x3 and one 6x3 which got me some decent flights but I really wished it would've worked with both 5x3's. No matter how rich they were set in the beginning, once the vibes started, they would both go so lean they would quit.  I also think that this was due to the cylinders mounted vertically. The engines would eventually fall into this vibration that was really ear piercing. The problem with horseshoe backplates is that you can't get to the screws when mounted sidewinder unless you put the needles opposing the cylinders.

           This week, I have some aluminum mounts that I can drill the horseshoe pattern on and mount either TD's or Medallions. My flying buddy has TD's on his and he's getting some pretty decent flights.