|Modifications Continued from Front Page|
|Electric Landing Brake:
When I did my landing brake actuator I calculated the loads in the actuator at 100 Kias and found that they were too high for the actuators that most people were using (and still are) for a direct connection. So I designed a sissors mechanism that increased the load at the nearly fully retracted position (when the loads are low anyway) and decresased them at the fully extended position. Since there are proably 100 of these flying with the direct mount and I have heard of no popped breakers or failed actuatore, this was probably unnecessary. But it's done and didn't add any significant weight. Mine is either full up of full down and there is a mioro switch to warn if not fully up. The electric actuation allows elimination of the center console giving more hip room. Instead I put an arm rest that folds up out of the way.
Electric Pitch Trim:
I also designed my pitch trim before the Strong system was around so it's a bit different. I found on my Cozy 3 that a fiberglass cantilever spring work better than the screen door springs used in the stock trim. So I incorportated that spring and a small linear actuator. I attached the actuator to the same trim lever as stock. This way I can trim manual or electric. There is enough travel to overcome the electric actuator even if it goes hardover in one direction. Here's some photos of the spring and actuator.
Map Pocket Width:
The standard map pocket is so small that it is hard to get your hand in sideways to reach the bottom. I increased the width to about 2.5". This helps a lot. I had to increase the width of the seat brace and heat duct locally to support this Here are some photos or the seats and the map pocket.
Nose Landing Light:
I don't care for the idea of a retractable landing light. It can't be deployed at cruise speed for traffic avoidance, is more complicated and is another thing to do. Plus in the standard spot you get a shadow from the nose strut. I mounted a halogen car head lamp in the nose cone. I made the cone removeable and put a clear lens over it, molded to the shape of the nose. I didn't want the pitot tube in the nose anyway so I moved that.
Relocated Pitot Tube:
I moved the pitot tube from the nose where it can get dirt kicked into it when parked nose down. The new location is just aft of the nose infront of the nose access door. It is a permenent stailess steel tube mounted such that the sensing part of the tube is parallel to the skin at that location. This is the same location as my Cozy 3 which had no position error.
Lay Down Brake Cylinders:
Once again these were designed prior to the prefab rudder pedels available today. I would probably go with those today. I mounted the cylinders on the NG30 with and aluminum rod going thru both NG30 and one cylinder on each side. This is the same arrangement I had in the Cozy 3 but in that airplane I found that the left brake felt springer than the right from the pilot's side and vice versa from the co pilot's side. This is becasue on eac side one brake is connected directly to the cylinder and the other goes thru a torque tube to the cylinder on the other side. To correct this I increased the size (diameter) of both torque tubes. They feel pretty much the same now.
Roll Trim System:
I found that the standard roll trim system puts a side load on each of the pilot and co-pilot roll torque tubes which causes quite a bit of friction in the roll system. I plan to put an electric trim system in but have not yet designed it.
Fuel Vent Location:
I would not do this again and may revert to the standard system. For now the vent is on the top of the turtle back just behind the canopy. I chose this location so that it was always the high point even in a climb. I put the vent tube in the tank all the way in the rear so it would be above the fuel level when parked nose down. Eventhough the vent opening in the tank would be below the fuel level if the tank were full in a climb, the opening to the outside is much higher than the high point of the tank. Also with the vent up high and no lower return this design can not syphon. The down side is that in a roll over the fuel will drain out the vent. I've also found that when full and parked level, the heating of the fuel and air in the tank can cause fuel to seep out the vent.That is easily solved by parking nose down. Or if the tanks are full, go fly.
The most noticable modification is the cowling. I reshaped the cowling to fit the SVX engine. I thought initially that I could keep the standard cowl shape. But Since I used the stock intake manifold and placed the upper engine mounts a little higher than necessary. So I added two blisters that cover the two upper mounts and the intake manifold corners. Since this is directly behind the rear windows, I had to terminate the blisters back to standard contour behind the windows. In retrospect, it would have been better to reshape the entire turtle back to blend into the cowl. This would eliminate the blister and provide more rear seat head room. I could not have lowered the engine any more because it is already very tight for the radiator below the engnine.
Since the engine depends on both electronic ignition and electric fuel pumps, the electrical system is esscential. For this reason I modified the electrical system to be more robust. The schematic is shown here. I incorportated two batteries and a 65 amp alternator. There is also a low voltage warning system which senses if the voltage drops below 14.0 volts. It then provide a bright pulsating LED warning light and automatically applies voltage from the highest battery directly to the fuel pump and ignition. So, even if the entire electrical system fails, other than one battery, the engine will still run. In fact the master can be shut off and the engine will still run (seperate kill switch). There are also redundant fuel pumps incase of a pump failure.