Q A_Round_5_(3-22-13).pdf

DARPA-BAA-13-19

VTOL X-Plane

Proposers’ Day Questions and Answers – Round 5 22 March 2013

VTOL X-Plane BAA-13-19 Questions & Answers – Round 5 (Proposers’ Day)

IN THE EVENT OF ANY INCONSISTENCY BETWEEN THE ANSWERS PROVIDED

HEREIN AND THE BAA, THE BAA SHALL TAKE PRECEDENCE

Q21. The flight profile specifies a dash leg for 15 minutes at 95% power. In some concepts, this could yield inefficient cruise at speeds above 400 kts. Can we assume a maximum speed or more efficient cruise/dash condition in such a case?

o A21. The standardized flight profile is meant to give the proposer the opportunity to showcase the performance of their flight demonstrator. As long as the proposer provides performance substantiation for the flight profile in the BAA, the proposer can present additional performance benefits of their concept. The 15 min. sustained high-speed segment should, however, be within the 300-400 kt.

Q22. How important is it to have a VTOL solution above 300 kt.? Will a solution that is new, innovative and creative below 300 kt. be considered?

o A22. The VTOL X-Plane speed objective is 300-400 kt. It is DARPA’s intent to fund a VTOL solution that meets the objectives specified in the BAA.

Q23. Will DARPA provide specific applicable formulas for ideal hover efficiency for different classes of system if appropriate (open rotors, ducted props, fans, etc.) so there is no potential question on reference points?

o A23. DARPA cannot predict or formulate ideal efficiency trends for all the concept variants that may be proposed to meet the objectives of the VTOL X-Plane, especially those comprised of mixed lift systems. The proposer should substantiate the predicted efficiencies at the system and, as applicable, sub-component levels to exemplify the hovering efficiency of the proposed concept.

Q24. What is the relationship between this DARPA BAA and the Joint Multi-Role Technology Demonstrator Phase I BAA? Both appear to seek a high speed VTOL with long range.

o A24. There is no intentional relationship between this BAA and the JMR-TD BAA. The two programs seek to develop and demonstrate very distinct technologies and capabilities.

Q25. Is this for a manned or unmanned vehicle? Does it matter which is proposed?

o A25. Proposers are free to submit concepts in either category as stated in the BAA Part 2.I.B on page 9.

Q26. Since off-the-shelf propulsion is required, then aircraft must be scaled to existing engines. Since cost favors single engine, why can’t the vehicle be large but less than 10,000

lb. gross weight (7,500 lb. gross weight for example), if scalability is demonstrated?

o A26. DARPA has set a constraint for the VTOL X-Plane gross weight to be between 10,000 and 12,000 lb. DARPA believes this gross weight range is well suited to demonstrate technologies and provide future transition opportunities that may be scalable to lighter and heavier aircraft.

Q27. While the government will not provide an engine as GFE, can proposers assume that they can purchase the appropriate engine (using government funds) for the phase II/III prototypes?

o A27. DARPA will not be providing GFE. The proposer is free to accept GFE from other government agencies, or use program money to purchase engines as necessary to support the development of their demonstrator aircraft. It is important to discuss any financial and schedule risks that may be introduced into the program with the inclusion of GFE.

Q28. Conventional hover efficiency is in terms of hover time (in minutes) per unit fuel (in terms of % GW). The BAA metrics emphasize figure of merit, which is maximized at higher disk loading, so toward poorer (hover time / %GW fuel). Please clarify if the (hover time/%GW fuel) is of interest.

o A28. The program seeks to improve the hovering efficiency of the aircraft, not just the figure of merit of the rotor or lifting system. The objective for hover efficiency is to be within 25% of the ideal efficiency during hovering flight. The actual power loading at a specified disk loading can be compared to the ideal power loading to determine whether this objective is met. While hover time will not be explicitly measured, the ability to perform a sustained hover is one of the goals of the program.

Q29. Funding for two demonstrator aircraft is very low. Is DARPA anticipating acquiring additional funding or will industry be expected to provide significant cost-share?

o A29. There is no requirement for industry to cost share. DARPA is requesting a cost ROM for future phases to understand the anticipated scope of effort required.

Q30. Can you discuss which services are supporting this initiative and how DARPA is/will ensure service support?

o A30. DARPA has presented the VTOL X-Plane program and objectives to the services and other organizations prior to initiating the effort and releasing the BAA. Several services have expressed interest in the objectives. The DARPA VTOL X-Plane program manager will further continue to pursue transition opportunities as the program progresses.

Q31. Will the list of attendees for Proposers’ Day be issued?

o A31. Yes, a list of those attendees who agreed to have their information published has been posted to the Proposers’ Day website at:

http://www.schafertmd.com/darpa/tto/VTOLXP/ under “ATTENDEES.”

Q32. In phase I, do you want to see a single concept, or would you be interested in seeing a limited number of concepts (say 2 or 3) featuring different configurations/technologies?

o A32. Each proposal for Phase I should present a single concept with supporting substantiating data and documentation as described in the BAA. DARPA is not interested in an analysis of alternatives study.

Q33. To what extent does shipboard compatibility play? Please clarify shipboard compatibility.

o A33. Shipboard compatibility is a design consideration, not an objective or constraint.

Each proposer may highlight the benefits of their proposed concept with respect to operation from ships.

Q34. Can you explain why no range requirement is listed in the “cruise-in” and “cruise-out” mission specification?

o A34. The information is requested from the proposers. The VTOL X-Plane objectives are related to transformational improvement in cruise efficiency, hover efficiency, speed, and useful load. The standardized flight profile is not a sizing mission but a way to understand the performance of the proposed aircraft.

Q35. The BAA seems to imply that open rotor systems (more traditional VTOL solutions) are NOT the focus for the X-Plane. Can you clarify the criteria that would be used to determine or rank proposed VTOL approaches?

o A35. There is no ranking of proposals. Proposals will not be evaluated against each other since they are not submitted in accordance with a common work statement. Rather, they will be evaluated on the basis of their individual merits. Evaluation of proposals will be accomplished through a scientific/technical review of each proposal. Any and all concepts / configurations that meet the objectives will be considered based on the feasibility of the submitted proposal and available funding. There is no predetermined preferred design configuration of interest to DARPA. Proposers are asked to exemplify the attributes of their concepts.

http://www.schafertmd.com/darpa/tto/VTOLXP/

Q36. The BAA mentions an “equivalent” disk loading of 120 psf and refers to ground footprint velocities. What are you really seeking with this statement in the BAA? Are you trying to control or minimize the ground footprint velocities to a specific requirement?

What is the requirement?

o A36. The 120 psf disk loading is provided as a design consideration with the intention of enabling safe personnel operations near and below the aircraft. No specific requirement is stipulated, and it is recognized that for aircraft with multiple lift or thrust systems, velocities and loadings may vary across individual sub-components. Concepts comprised of mixed disk loadings are relevant provided they meet the VTOL X-Plane program objectives. Proposers are encouraged to emphasize the advantages that may be unique to their systems.

Q37. What does “equivalent disk loading” mean? Is this the average loading or maximum loading? Can one or more lifting posts be higher than 120 psf if the ground velocities meet your unspecified ground footprint velocities?

o A37. The 120 psf disk loading is not a constraint but a consideration in regards to downwash and safe human operation below the aircraft. Equivalent disk loading is computed by dividing the lifting force generated by the effective disk area of the rotor, or of the engine fan intake, for instance.

Q38. Can you provide some guidance on the Technology Readiness Level (TRL) or technologies that can be considered?

o A38. There is no TRL requirement for technologies in this program, but the proposed technologies and concepts must be flown on a technology demonstrator aircraft within the schedule constraint provided in the BAA. Proposers are welcome to offer concepts (configurations, sub-systems and integration approaches) that can be demonstrated within the stipulated time frame as part of the technology maturation plans and risk analyses provided with the proposal.

Q39. Dr. Tousley mentioned that cost was a critical criterion in establishing the transition business case and should be a consideration. What is the cost metric that will be used to evaluate cost? What is the business case that DARPA is looking to make?

o A39. The cost metric to be used for this program is provided in the cost realism evaluation criteria on page 35 of the BAA. DARPA is looking for technologies and configurations to enable capabilities for the US warfighter.

Q40. How important is the actual value of power loading (lb./Hp) compared to figure of merit? Assuming that everyone has similar engine options, the actual value of power loading is very important to gauge efficiency, fuel consumption, etc.?

o A40. The appropriate metric to use is the actual power consumed in hover, and not the installed power.

Q41. Why do I have to hover? What mission demands hover? Is an approach to a “no hover landing” to a spot acceptable?

o A41. The ability to perform a sustained hover and do useful work is a fundamental objective and core principle of the VTOL X-Plane program. Sustained hover capability is a critical necessity for transition opportunities in the future.

Q42. Has DARPA defined a flight test location and how will the airworthiness certification be made?

o A42. At this time, DARPA has not finalized plans for the flight test phase of this program. It is DARPA’s intention to provide all relevant flight test and safety of flight requirements and information to Phase I performers by the end of Phase I. Proposers are also encouraged to include any plans and relevant capabilities in their proposals.

Q43. Under Performance Objectives, the following is stated:

"2. System (aircraft) hover efficiency within 25% of the ideal power loading (at sea-level standard conditions), which for open rotors (for example) is given by PL = κ (2 ρ / DL)1/2, where PL = T/Pact, T = thrust required to hover, Pact = actual power required to hover, κ = aircraft non-dimensional coefficient of efficiency, ρ = density of air, DL = T/A, A = equivalent actuator disk area."

There are three possible types of hover for VTOL craft.

a) IGE in ground effect,

b) NE Near Earth,

c) HA High Altitude Hover.

What type of hover performance is the solicitation requesting? If it is a Near Earth Hover, please state altitude target and metric. (i.e., 500 ft. above ground level or 500ft above sea level) o A43. Hover efficiency should be demonstrated at sea level standard conditions, out-of-ground effect.

Q44. If electric propulsion is used in the concept, can an electric motor of the correct size be built?

o A44. The program is constrained to using existing designs. If electric propulsion components are not available and must be built, the technical, cost and schedule risks to the program should be addressed in the Technology Maturation/Risk Analysis Plan. If the motor is a new design, or scaled version of an existing motor that has not been built before, then it is considered a new development and is outside the scope of the DARPA funded effort.

Q45. Can a gas turbine engine be re-fanned?

o A45. If modifications to an engine need to be made, the technical, cost and schedule risks to the program should be addressed in the Technology Maturation/Risk Analysis Plan. If changes required are major, and essentially amount to an engine specific development or redesign effort, then they are outside the scope of the DARPA funded effort.

Q46. What is the hover endurance requirement in terms of minutes of hover? In other words is hover efficiency momentary or over time. If my system for vertical flight is electric or fly-wheel based, it requires forward flight mode for several minutes to recharge batteries for landing and another takeoff. Is whole mission efficiency a consideration being evaluated?

o A46. The hover efficiency objective is evaluated at sea level standard OGE. While the program does not require the demonstration of measured hovering time, it does stipulate the ability to hover for sustained periods and at any point during a “mission.” The proposer is encouraged to emphasize any additional advantages their concept may have, including “whole mission efficiency,” provided the performance objectives listed in the BAA are met.

Q47. How many awards are anticipated for Phase 1?

o A47. DARPA does not have a predetermined number of awards that it will make for Phase I.

Q48. When and where will you post the slides you presented at the 14 March Industry Day?

o A48. The slides have been posted at the Proposers’ Day registration website at:

https://www.schafertmd.com/darpa/tto/VTOLXP/index.php under “MATERIALS” https://www.schafertmd.com/darpa/tto/VTOLXP/index.php