AAE 451 – Team 3
Design Requirements and Objectives: Revision A
10/21/2003
Brian Chesko
Brian Hronchek
Ted Light
Doug Mousseau
Brent Robbins
Emil Tchilian
The following paper is a revision to the original DR&O. Upon analysis of the constraint diagram, it was determined that the take-off distance was an active constraint. Since this constraint was set at the entire length of the runway, the constraint diagram gave a power loading that did not allow any buffer in case of problems. It would have taken the aircraft the entire runway to take-off.
For the previously given reasons, it was decided to change the take-off distance requirement. Roskam’s Airplane Design” Part 1 correlates take off distance to runway distance (assuming a height of 50 feet above the end of the runway) for FAR 23 capable aircraft. Although this requirement does not apply to our application, it was decided that this requirement would certainly be adequate (probably conservative). The correlation is found in Figure 3.4, and gives a take-off distance of ~106 feet with a runway length of 175 feet.
No other changes have been made to this document.
AAE 451 – Team 3
Design Requirements and Objectives
Brian Chesko
Brian Hronchek
Ted Light
Doug Mousseau
Brent Robbins
Emil Tchilian
This paper will explain the requirements and objectives that will direct the design of the aircraft for AAE 451. For the purposes of this paper, both design requirements and design objectives will be explored. Design requirements are considered minimums, both quantitativelyand qualitatively, that the aircraft must meet. Design objectives are goals that are not necessary to meet, but would help in the marketability of the aircraft. Objectives were added to this mission to make the aircraft more marketable. These objectives will not be used as design constraints such that they will not be allowed to drive the design, however, if they are met, the aircraft will be much more marketable.
First this paper will explore the qualitative requirements and goals. Then the quantitative requirements and goals will be listed.
Among the qualitative goals and requirements our team has set for our design, high on the list is an aircraft that is easy to construct. This requirement goes well with the hard limit set for cost of construction. This ensures that in the following semester, the aircraft can be built well in the time allotted and under the budget set. An aircraft that is relatively easy to build will ensure that it can be built robustly so that it can be used for years to come. Ease of construction also lends itself well to adaptability and repairability, which are also among our team’s objectives for the design. Adaptability allows our aircraft the possibility of taking on diverse missions and applications. This makes our aircraft marketable to a broader spectrum of customers. Most notably our aircraft will have an adaptable wing-to-fuselage connection, so that the aircraft will be capable of being fitted with wings of varying sizes.
Another requirement our team has set is the capability for using rough surfaces for takeoff and landing. At this stage in our design, our way of achieving this capability is not defined, but could likely include rugged landing gear, shocks, or larger wheels. This requirement will ensure that our aircraft can takeoff and land on a variety of surfaces that may be necessary for the diverse range of applications we will market towards.
The gross takeoff weight (GTOW) of the aircraft is required to be 55 pounds or less. This is the main requirement that the aircraft must meet, and all other parameters of the aircraft will designed around this constraint. This requirement exists for several reasons. The main reason for the requirement is to allow the aircraft to be qualified for American Modelers Association insurance. This will prevent the cost of insuringan aircraft over 55 pounds. A second important reason for keeping the weight limit to 55 pounds and below is manufacturing cost. Aircraft cost is a function of weight, thus to minimize cost our team is designing for a low weight aircraft.
Another constraint on the design of this aircraft was to keep the cost of construction below $300. This cost does not include the cost of the radio-control gear, engine (internal combustion or electric), and avionics (camera(s), computer, inertial navigator, GPS). This constraint was imposed on the aircraft by the customers, and will not be exceeded without consent from the customers.
A required stall speed of less than 30 ft/sec and a maximum speed of greater than 50 ft/sec are also impinged on the design of the aircraft. These constraints were made by the customer to ensure that the camera system could take pictures of objects at slow speeds and alsocruise to a destination in a reasonable amount of time.
The aircraft will have the ability to carry a 20 pound electronics pod with dimensions of 14 x 10 x 20 inches. This pod size will give ample space for the entireavionics systems payload. The aircraft will also be able to carry the air data boom, which will link to the electronics pod.
Other requirements imposed by the customers include a climb angle greater than 5.5 degrees. In addition, the aircraft will be required to takeoff in a distance of 175 feet*, the length of the runway at McAllisterPark. The aircraft is also constrained to have an endurance time of 30 minutes and be able to cruise at an altitude of 1000 feet or greater. 30 minutes of endurance time is necessary to allow the aircraft to have enough time to perform its mission, which would include warm up, taxi, takeoff, ascend, cruise, loiter, descend, and land. During loiter, the aircraft will need sufficient time to take photos and maneuver around the object of interest. Our team would like the aircraft to be capable of reaching altitudes of 6500 feet and cruising greater than 1 hour. This capability will allow the aircraft to perform various missions across the United States, thus increasing the aircraft’s marketability.
*Rev A (10/21/2003): Upon analysis of the constraint diagram, it was determined that the take-off distance was an active constraint. Since this constraint was set at the entire length of the runway, the constraint diagram gave a power loading that did not allow any buffer in case of problems. It would have taken the aircraft the entire runway to take-off. For the previously given reasons, it was decided to change the take-off distance requirement. Roskam’s Airplane Design” Part 1 correlates take off distance to runway distance (assuming a height of 50 feet above the end of the runway) for FAR 23 capable aircraft. Although this requirement does not apply to our application, it was decided that this requirement would certainly be adequate (probably conservative). The correlation is found in Figure 3.4, and gives a take-off distance of ~106 feet with a runway length of 175 feet.
Table 1 shows a summary of the requirements and objectives to be met in this design.
Table 1: Design Requirements and Objectives
Design Requirements / Design ObjectivesMaximum weight < 55 lbs
Cruise speed > 50 ft/sec
Stall speed < 30 ft/sec
Climb angle > 5.5 degrees
Operative ceiling > 1000 ft / Operative ceiling > 6500
Flight time > 30 minutes / Flight time > 1 hour
Payload of 20 lbs in 14x10x20 pod
Spending limit < $300
T.O. distance < 106 feet (McAllisterPark runway length) see Rev A note above*
Rough field capabilities
Detachable wing / Multi-mission capabilities (adaptable wing)
Easy construction / Easily repairable
Carry pitot-static boom