Byron Pitts Special Manual
I finally got around to the maiden flight last week and it was interesting to say the least. As expected, the Pitts is very tricky on the takeoff roll. It took me 3 attempts to get it airborne. The first 2 resulted in what I would describe as spin outs. On the 3rd attempt I got the tail off the ground ASAP and it was much better. The flight itself was surprising in that the roll axis was very slow.
As I mentioned previously I only installed ailerons on the bottom wings and I had the throws set very conservatively. That combined with the new engine not yet broken in a produced a flight much slower and tamer than I was expecting. The landing was also a surprise in that it was easy and uneventful.
I used a very short final and approach which seems to work best with a Pitts. More after I make some changes.
Mac, I don't agree that it was supposed to have a drive unit with a 60. Byron did sell that package but, in my opinion, it was a real bust. The engine would be screaming along with the plane barely able to do a few mild aerobatics. Back in the early 80s the Byron Pitts was very popular. There were always at least two at every big bird flyin.I originally had a Quadra 35 in mine and later swapped out to a Tartan twin which I think was about 2.67 cuin.
The Tartan was probably the ideal low vibration engine for the Pitts. Excellent aerobatic capabilities at around 18 pounds. I then made a mistake that I always regretted.
I sold the Tartan twin and bought an A&M 3.7 cuin Sachs-Dolmar engine when Al was converting the chainsaw engines to airplane engines. I was wanting unlimited fast vertical. I got it but with a balanced weight penalty of about 4 pounds. That made a real fast pig out of an otherwise great flying plane. The landing speed probably went up to 40 mph. Truly horrible.Even with the big engine I never experienced the plane trying to shake apart.
Foam has a great ability to absorb a lot of vibration. I said before that I would probably put a G-62 in it but after thinking about it a little more I think I would limit the engine size to around 50cc. The 40cc would probably be fine. Did you come up with the Byron kit or was it built by someone else?NM2K 03:40 AM. ORIGINAL: 1st Lt MacHelloI just bought a Byrons pitts and I`m looking for info on engine selection and what to do to beef up the firewall to handle a gasserThanksMac-The original firewall is 1/8' plywood. If you stay with a mild 40cc engine, the stock firewall will be just fine.Be sure to coat the interior of the fuel tank area with epoxy. Gasoline makes foam disappear very rapidly.
It is a great flying plane, but glides like the Space Shuttle. At the first sign of an engine out situation, lower that nose quickly or you will find the plane flying so slow that the controls have no effect. Ed1st Lt Mac 08:47 AM. Hello Ken,I bought the plane built from a club member. The plane is not finished and has never been flown.It looks as if it has a thin coat of glass on the fuse and wings then primer and the inside is still raw foam.Should I coat the inside with something to protect it from the gas?Also the firewall seems to be inset and then glued with no type or reinforcement at all. I was thinking of adding someglass to the inside of firewall area and then cap the firewall.I must admit I have no experiance with a foam plane at all and using fiberglass I may just end up selling the plane all the work it needs seems to overwhelming to get in the airScottBigBird 10:06 AM.
ORIGINAL: 1st Lt MacHello Ken,I bought the plane built from a club member. The plane is not finished and has never been flown.It looks as if it has a thin coat of glass on the fuse and wings then primer and the inside is still raw foam.Should I coat the inside with something to protect it from the gas?Also the firewall seems to be inset and then glued with no type or reinforcement at all. I was thinking of adding some glass to the inside of firewall area and then cap the firewall.I must admit I have no experience with a foam plane at all and using fiberglass I may just end up selling the plane all the work it needs seems to overwhelming to get in the airScottScott, one thing that you might want to do at this point, since the firewall has not been fiber glassed is to epoxy a layer of 1/8' lite ply to the firewall.
This will stiffen it up. Then epoxy 1 1/2 wide strip of 2 ounce glass over the foam and overlap the firewall by 1/2'. I don't think fiberglassing the inside of the firewall will buy you anything.Ed had a very good suggestion, which I did to mine. Coat the inside of the fuselage back to the lower wing with epoxy.My Pitts was covered with low temperature Econokote to save weight.
The only concern that I would have with a glass and epoxy coating would be with weight. It will be more durable. If the guy who covered it used very lite cloth and was stingy with the epoxy then it should be fine.Don't be discouraged about the work needed to get it in the air. When you finally get it flying you will be richly rewarded.
Byron Pitts Special Manual 2017
If you wanted an ARF then maybe you should have gotten one instead. Great Planes makes a really nice Pitts Special ARF.TLH101 10:26 AM. Hello Ken,What I meant by fiberglassing the inside of firewall was to take strips and lay them inside the fuse where the firewall met the foam and overlay it as you described,I dont know if you meant on the outside or inside with the glass. Then I would continue to coat the foam with epoxy to protect it from the gas, then I was going to cap the firewall with some lite ply. I will weigh the model as it sits with no engine or electronics and will post some pics. I will try to do that later today.Any idea what a tartan would cost me like you used?As for the GP Pitts I have one with a Fuji 50cc I have it for sale here on RCU since I got the Byrons I was going to sell itScottBigBird 10:58 AM.
Looking at your location, did you work for Byron Originals? One of the most fun trips that I made many years ago was to the annual flyin in Ida Grove. I rode up there in a motor home owned and driven by Fred Illston, former Chief Pilot for American Airlines.
My two riding companions and good friends were Chuck Cunningham (RCM writer) and Bill Slater. I took the tour of the model factory and the fuel blending facility. It was a first class operation all the way. Some of the highlights at the flyin were the flight of the huge B-29, the WWII Fighting back show and the flight of the full scale BD-5J.
Too bad the flyin went away.rckitmasters 01:10 PM. I agree with Ken.The model is worth the work. Luckily, none of the work is all that critical and Byron tells you how to align the model properly.It is a great flyer.The only caveat is landing. Practice making delicate landings with a heavy, high drag smaller glow model (another bipe!) before flying your Byron Pitts. The landing gear appears to be the weak spot in the model.
Every model has a weaker spot than somewhere else, so this is not a big deal.The first quarter scale, gas powered model to fly at our field was a Byron Pitts powered by a Quadra 35cc engine. I was the test pilot and it was my first giant scale, gas powered anything. At the time I was flying pattern a bit, so I was in good shape, but it still scared me silly.
Especially when the model throttled up and took off by itself. It took a little head scratching to figure that one out. Yes, I landed it successfully. Ed Cregger'Folks, ignore that pilot with the wet spot on the front of his pants!' Antique 02:38 PM.
Go to the hardware store and go to the spackle section. Begin picking up containers of spackle until you run across one that is greatly lighter than the rest, of the same size. This is the stuff you want to use, to fill in those dings in the bare foam.Next, never sand your model with a sheet of sandpaper in your hand. Or you will get the effect that you so rightly fear, even with the very soft, light weight spackle.Always use a sanding block behind the sandpaper.
Cut up a bunch of sanding blocks from pine, or whatever wood you have laying around.Oops, almost forgot. Before cutting up those boards to make sanding blocks, find a friend with a planer that will make the boards absolutely flat, then go ahead and cut them up. Make them ridiculously large and ridiculously small with every size in between. You will be amazed at how this single move can greatly affect the beauty of your models. You will also be amazed at how jobs you once dreaded have become enjoyable. No, not painting the house. Ed Cregger1st Lt Mac 12:54 PM.
Scott, the Pitts looks pretty good in the photos. The Tartan twin should be a good engine for the plane providing it really is in good condition.
As I recall, I used to mix my own fuel. I would buy a gallon of 21% FAI (no nitro) fuel and mix it with 2 gallons of Methanol. This would make 3 gallons of 7% oil fuel. I believe that this was the correct mixture for the Tartan twin. The engine has ball and roller bearings and does not need the high oil content. Maybe the guy still has the original instructions for the engine.
Tartan stressed using very low or no nitro fuel.Another thing that I found out about the twin was this. The carburetor had a yellow plastic ram air intake. While this looked pretty cool it could be a problem. I had opened the carb air intake on the front of the Pitts cowl because it seemed logical that this would work well with the ram air intake. When I was flying the plane along at full speed and suddenly went to idle the engine would die.
All that air coming in would make the Delorto carb to go lean. The solution was to cover up the hole on the cowl.When my engine was cold it would always start on only one cylinder. I would let it run about 30 seconds and kill it. On the restart it would usually start on both cylinders. Just an unusual quirk I guess.
I think I used to crank it backwards with a chicken stick to start it.It was a very good engine. Maybe someone else with Tartan twin experience will jump in.JET FX 08:42 AM.