21. Propeller aircraft use one or more propellers ( airscrews ) to create thrust in a forward direction. 22. As the road was built in the forward direction, it was necessary to build 278 artificial structures. 23. After removing the barrel, the bolt and return spring are removed in a forward direction, completely dismantling the gun. 24. We made some strides in the last few weeks, but we have to keep moving in a forward direction. 25. The radiation is thus strongly collimated in the forward direction and can be assumed to be parallel for lithographic purposes. 26. Its forward direction to the west-northwest was due to an influence by a deep-layered ridge of high pressure over Mexico. 27. On the quantum level, we picture this as incident photons all traveling in the forward direction and being scattered isotropically. 28. If " g " approaches a value of 1 this indicates that the scattering is primarily in the forward direction. 29. This then adds to a total of 90?when the light travels in the forward direction and then the negative direction. 30. Sailing into the wind is possible when the sail is angled in a slightly more forward direction than the sail force.