Procurement Guidance

SFR Procurement Guidance

Evaluating simulation systems using the SFR framework.

This document explains how organizations can apply the SFR framework when evaluating simulation systems for procurement. It covers the questions to ask vendors, the architecture considerations that matter, how to apply the evidence hierarchy during evaluation, and how to conduct a structured documentation review. It does not endorse any manufacturer or specific system.

Section 1

Questions to Ask Vendors

The following questions are derived directly from the SFR criteria. A vendor who can answer these questions with documented evidence is providing the inputs needed for a criterion-level assessment. A vendor who cannot answer them — or who answers with marketing language rather than architecture documentation — is providing Tier 4 evidence, which carries no weight in the SFR evidence hierarchy.

Is the motion in this system derived from the live vehicle physics state, or is it generated from a pre-programmed or scripted profile?

This is the direct test of Criterion A (Causative Accuracy). The answer should be accompanied by architecture documentation showing the data path from physics model to actuator command.
Where is motion calculated? Is the cockpit motion resolved at the vehicle's center of mass, or at a different reference point?

This tests Requirement 2 (Center of Mass Reference). Motion resolved at a point other than the center of mass introduces geometry errors that cannot be corrected downstream.
Can each motion axis operate independently, or are axes mechanically or computationally coupled?

This tests Requirement 3 (Independent DOF). Coupled axes cannot simultaneously produce independent physics events without cross-axis contamination.
What is the timing relationship between the physics event in the model and the onset of the motion cue at the cockpit? Can you provide synchronization telemetry demonstrating this?

This is the direct test of Criterion B (Temporal Coherence). The answer must be accompanied by measured telemetry — not a specification claim. A claimed timing value without telemetry support is Tier 4 evidence.
Does the visual system receive timing from the physics model, or does it run on an independent timing cycle? What is the synchronization method?

Multi-channel temporal coherence requires all sensory systems to be synchronized to a common physics reference. Independent timing cycles risk the visual system leading the motion cue, which inverts the correct temporal relationship.
Can you provide architecture documentation, a physics model specification, and actuator specification documents as part of the procurement package?

These are the Tier 2 evidence documents. An evaluation conducted without them must rely entirely on telemetry (Tier 1) or falls to Tier 3 (observation). Complete documentation is standard for any engineering product procurement.

A vendor who cannot answer these questions with documentation is asking you to rely on Tier 4 evidence alone. No classification determination can be made from Tier 4 evidence.

Section 2

Architecture Evaluation Considerations

The following architectural properties determine a system's classification under the SFR framework. These should be evaluated before committing to a procurement, not after.

Motion Origin

Does motion originate from the physics model output, or from a motion cueing algorithm that processes a scripted or filtered representation of vehicle dynamics? Systems in which motion is "inspired by" physics rather than derived from live physics state classify as surface-level regardless of the physical capability of the motion hardware.

Center of Mass Reference

Is the cockpit motion calculated relative to the vehicle's center of mass? This is a geometry question, not a capability question. A system can have excellent motion hardware and still fail this criterion if the reference point is incorrect.

Independent Degrees of Freedom

Can the system produce independent yaw, pitch, roll, surge, sway, and heave events simultaneously without any axis coupling that degrades timing or magnitude? Mechanical coupling between axes is a structural limitation that cannot be resolved by software.

Temporal Synchronization

How are the physics engine, motion system, and visual system synchronized in time? This question should be answerable with a timing diagram from the vendor's architecture documentation. Systems without a defined synchronization architecture are at risk of temporal incoherence under compound-axis conditions.

Latency Chain

What is the total latency from physics event to motion cue onset? This includes physics computation time, communication delay, motion controller processing time, and actuator mechanical response time. Each stage adds to the total. Evaluate the chain end-to-end, not individual stages in isolation.

Scalability vs Architecture

Is the vendor describing what the system currently does, or what it could do with future upgrades? Architectural limitations (reference point, axis coupling, synchronization method) are typically not resolvable by software upgrade. Capability limitations (travel range, force output) may be. These two categories require different procurement treatment.

Section 3

Evidence Hierarchy in Procurement

The SFR evidence hierarchy (defined in the Evaluation Process document) applies directly to vendor claims received during procurement. Understanding which tier each piece of vendor-provided information occupies determines how much weight it should receive in your evaluation.

Tier 1

Measured Telemetry — Highest Weight

Calibrated, timestamped data from the system operating under defined test conditions. In procurement, this means requesting a structured evaluation session using the reference test methodology, with telemetry capture of all required inputs. Tier 1 evidence is the gold standard for procurement decisions involving physics-fidelity claims. If a vendor is unwilling to support a telemetry-captured evaluation, that itself is relevant information.
Tier 2

Architecture Documentation — High Weight

Physics model specification, actuator specification, synchronization architecture, system block diagrams. These documents allow a procurement team or independent evaluator to assess structural properties before committing to a full evaluation. Request these documents early in the procurement process. Their presence and quality is itself informative.
Tier 3

Observed Behavior — Limited Weight

Structured observation of the system during a demonstration, without instrumentation. Useful for identifying obvious failures but insufficient for classification. A demonstration conducted without telemetry is Tier 3 at best. Do not allow observed behavior alone to drive a procurement decision for a system where physics fidelity is a training requirement.
Tier 4

Manufacturer Claims — No Independent Weight

Marketing materials, brochures, website descriptions, sales presentations, testimonials, and claimed specifications. Tier 4 evidence cannot produce a classification determination. It cannot override any other tier. Its function in procurement is as a starting point for questions — not as answers. Every Tier 4 claim should generate a Tier 2 document request.

A procurement decision based primarily on Tier 4 evidence is a decision based on unverified claims. The SFR evaluation framework exists to convert Tier 4 claims into verifiable Tier 1 and Tier 2 evidence.

Section 4

Documentation Review Process

Before conducting any physical evaluation, request the following documentation from the vendor. The presence, completeness, and quality of this documentation is itself informative about the system's architecture and the vendor's ability to support independent evaluation.

Physics Model SpecA specification document describing the vehicle physics model: rigid-body equations used, center of mass reference, degrees of freedom modeled, and physics computation cycle rate. This document should describe what the model computes, not what the simulator "feels like."
Actuator SpecificationPer-axis actuator specification: travel range, maximum force, bandwidth, response latency, and control loop description. This establishes what the motion system is physically capable of and allows comparison against what the physics model is producing.
Synchronization Arch.A description of how the physics engine, motion controller, and visual system are synchronized in time. This should include a timing diagram showing the sequence of events from physics computation to sensory output across all channels.
Motion Source Arch.A description of the data path from the physics model output to the motion actuator command. This document should clearly show whether motion commands originate from live physics state or from a processed or filtered representation.
Reference Point Doc.A document or diagram confirming the geometric reference point from which cockpit motion is calculated. Must state whether this reference point corresponds to the vehicle's center of mass.
Previous EvaluationsAny previous independent evaluation results, telemetry captures, or evaluation reports conducted under structured test conditions. Independent evaluations are more informative than self-assessments.

For the full evaluation methodology, see Evaluation Process, Reference Test Methodology, and Evaluation Inputs.

Procurement Statement

Evidence Before Decision

Simulation procurement decisions have long-term training consequences. A system that classifies as surface-level under SFR criteria produces different training outcomes than a system that classifies as in-the-loop — regardless of their respective price points, feature lists, or manufacturer reputations. The SFR evidence hierarchy and evaluation methodology exist to give procurement teams a structured, architecture-neutral basis for distinguishing between these two outcomes before the purchase, not after.

Procure on evidence. Classify by structure. Training outcomes follow architecture, not marketing.