Sailing Short Stories
Airplanes And Sailboats
You may have noticed that airplanes look a little like sailboats. Well maybe not really, but there are lots of features that are common to both machines. They both use lift to move from place to place and people normally ride in them and control their movements. Some people control their movements better than others. You could call the Americas Cup boats flying machines during the last competition on San Francisco Bay. Understanding the similarities will help sailors be better sailors.
Airplanes and aircraft are one and the same thing. Helicopters are aircraft and they fly a lot like old aircraft from the early days of flying. They are slower than most modern jet passenger aircraft and they have lots of moving parts. The reason that modern jet passenger aircraft are as safe as they are is that they have fewer moving parts. Jet engines normally run at one speed and do the same thing hour after hour. Of course helicopters fly closer to the ground and that in itself is more dangerous. We could say that sailboats and helicopters are similar in the locations where they sail and fly. Sailboats go aground and helicopters sometimes hit things while they are flying close to the ground. Sometimes people shoot at helicopters during a military conflict.
You could say that if you were a good helicopter pilot, you could also be a good sailor. Therefore, you could also say that most experience sailors would make good helicopter pilots. I think both statements are true. I know several pilots that sail. An old helicopter pilot had his left hand on the collective and his right hand on the cyclic with his eyes on his instruments. He would sometimes look ahead to see where he was going. Doesnít that sound like a sailor with right hand on the tiller, left hand holding the sheets while he looks at the sails and checks his heading from time to time. You heard me say before that a sailor needs to be able to pat his head with one hand and rub his stomach with the other and do it at the same time. Not everyone can do that. If you canít do that now, you will get better with time and more sailing experience.
A pilot has one more control that's similar to a control on a sailboat. The helicopter pilot keeps his feet on two pedals. They are called rudder pedals they are not used very often. While a helicopter is flying, most pilots change direction by banking into a turn with the cyclic. They also have to adjust the collective at the same time if they want to maintain their altitude. A rudder on a sailboat is similar and it does the same thing as the pedals do on a helicopter. It changes the yaw axis of the sailboat. Every time you use your rudder to change directions, it's going to slow your boat. If a pilot used his rudder pedals to change direction, the aircraft would be flying sideways. They normally use the rudder pedals to fine-tune a directional heading and maneuvering on the ground. A sailor should balance his sails and then use very little rudder movement to maintain a course.
Pilots and sailors know that a banking turn is smoother and faster. A Com-Pac 16 can do a roll tack in light air that's smoother and faster than a flat turn. It requires more work and coordination and isn't required unless needed. If you didn't have a motor and you had to sail home, I would want to know about and be able to do everything I could do to get home. Pilots practice smooth turns and sailors should too.
All this airplane and sailboat talk is leading up to something interesting for sailors (maybe pilots). We know about LIFT and we know about POWER and we know about BALANCE. But do we know about DRAG? Thatís something that not many sailors think about and it is normally built into our machines. We know that our sails have pointed ends at the top of the mast. They could have square ends or round ends, but they have pointed ends. The mainsail starts at the bottom on the boom and if you add the jib, the bottom of sails take up the distance from the bow to the stern on most sailboats. As we go up, the sails get smaller from front to back with some twist. We know that sails produce power through lift (more pressure on one side than the other) and they also live in different wind speeds from top to bottom. The cause of this difference is drag. The wind passing over in close proximity to the water sees the water as a resistance and its speed is slowed. The wind at the top of the mast sees less resistance and has more speed. Looking at an aircraft, we can see that the wing of the aircraft in the picture below is larger at its base and get smaller as it moves toward the tip. The wingís airfoil is modified as it goes towards the wingtip. This design feature was discovered in the 1930s and we still use it today in airplanes and sails. The base of the wing on a Boeing 777 is large and the airfoil (camber) changes as it goes towards the wingtip. The aircraft sees drag at the fuselage caused by the fuselage and the drag become smaller as it goes outward toward the wingtips
Sailors and sometimes pilots get in trouble when they stall their power system. Itís easy to stall a sail and it also easy to stall the rotors blades of a helicopter. When you stall your lift device, you lose speed in a sailboat and a helicopter stops flying. A sailor can pull the twist out of his or her sail when they are on the wind. The sail is designed to compensate for the difference in drag with a built-in twist created when the sail was made. If we pull the leach flat enough with a sheet, we will stall the top of the sail. The main, jib and genoa all work the same way. If the wind is strong enough, you canít pull it flat and the sail will do well even if you do try to pull it flat.
The drag of some components used by sailboats discourages some sailors from sailing in light air. They use their big genoa and a mainsail in super light winds and they soon become a stationary object. The big genoa is the wrong sail in super light or no wind. The genoa's surface drag is greater than the power that can be generated by the sail in those conditions. Optimal sail configuration for a sailboat from zero to lots of wind is jib, genoa and jib. Use the jib in the super light stuff because it has less surface drag and then you should pick the wind speed that the genoa produces more power than drag and then again when the wind speed is too much for the big sail. In the World of sailing, one headsail can't do it all. If you are a trailer sailor, picking the right sail when you launch is important. Not many trailer sailors change sails while they are on the water. If you are sailing across an ocean, you could have as many as 10 headsails and changing a sail to get more speed is no problem. The look of wind speed on the water is the same everywhere. If the water looks slick, a jib might be the best sail. If you can see any water movement from the wind on the water's surface, it might be time for a larger sail.
Pilots always land into the wind because they have greater lift and control with more wind. Landing downwind isnít recommended. If a sailboat wants to get to a dock with accuracy, an on the wind approach is best with a beam reach on the last tack. Sailing into a slip with a downwind approach is very exciting and should be avoided. No brakes on sailboats.
Early Vietnam helicopters used reciprocating engines and they were always short on power. The Marines operated in the Northern I Corps area of South Vietnam. It had coastal and mountains areas with the altitude difference between the two. The air was thick on the coast and got thinner with altitude. The Marine Pilots used some of the same techniques that sailboat sailorís use today. A helicopter can lift more weight using a rolling take off. Increasing wind speed over the rotor system increases rotor lift. The rotor blades use blade pitch like we use sail trim or pitch. A helicopter pilot has to avoid blade stall and a sailor has to avoid slow sailing with a stalled sail. As the helicopter rolls down the runway, the pilot can pull more pitch without stalling his blades and he gets more lift. There are two helicopter flight parameters that can be related to sailboats. The first is HIGE and that stands for hovering in ground effect. When a helicopter comes to a hover over one spot, the helicopter is HIGE. When a helicopter comes to a hover and there isnít any ground under the helicopter, the helicopter is HOGE, or hovering out of ground effect. HIGE has more lift and HOGE has less lift. When you see a helicopter come in for a landing aboard an aircraft carrier and if the aircraft is loaded, the pilot will keep as much forward speed as possible until the aircraft is over the deck and in the HIGE envelope. If the aircraft carrier has forward speed and lots of wind across the deck, landing a helicopter on the deck is less problematic. Directing the downward rotor wash to the deck increases lift and a sailboat can do something similar by adjusting their sails where they compliment lift or what sailors call tuning the slot between the jib and the main.
Aircraft and sailboats are very similar in that if they are maintained, they will last forever. Iím not sure that moving our old military and civilian aircraft to the Arizona graveyard is a smart move. We should see a major boat builder pickup a reconditioning business soon and start building and selling custom reconditioned boats at boat shows and in magazines. The second time around is normally better than the first time. Knowing what the failures were the first time around and fixing them should make for a better boat.
One big similarity between vehicles is helicopter autorotation. When the engine stops running, the helicopter has to do something or everyone dies. Autorotation is a technique that saves the machine and the people inside. I have been there and done that. The pitch on the blades goes from positive to negative pitch when the pilot drops the collective after the engine stops. As the aircraft falls with gravity, the rotor system keeps on spinning with the negative pitch angle of the blades and the wind flowing through them. The helicopter is almost a sailboat at this point. In early Vietnam, the helicopters flew at 1000 feet and you had to be fast when the engine stopped. As the aircraft approached the ground, the pilot pulls up collective and he changes the aircraft's attitude with a little nose up. The aircraft will flare and the decent slowed for a soft landing if he is good. Pilots that auto rotate well can pat their head and rub their belly at the same time. Pilots practice autorotation and they get good with experience. If you sail, most sailors will have an engine failure at some time along the way. That means you will have to sail back to the dock. Practice sailing back to the dock without an engine is what most sailors need to become great light wind sailors.
The following stories involve Marine Helicopter Squadrons flying all over the World. See if you can pick out the similarities between sailboats and helicopters. The maintenance on both machines is about the same.
HMM-263, Early Vietnam (Autorotation Example)
HMM-165, Late Vietnam (The crash-landing on the mountain-landing zone in the Philippines is a good example of a heavy aircraft trying to HOGE in thin air)
HMM-162, Mine Removal Suez Cannel (Egypt has changed a lot since we were last there)