Pegasus

This is not fine This article requires considerable cleanup to meet SSI wiki quality standards. Please help the SSI Wiki by correcting formatting and fixing errors in content and organization.

---

---

Stanford Student Space Initiative

Pegasus (ARES-2) Preliminary Design Review

image

---

---

Team Summary

Stanford SSI Rockets Team - Pegasus,
Leland Stanford Junior University
Stanford, CA
Ian Gomez
Project Manager
iangomez@stanford.edu
Marie Johnson
Team lead
mj6@stanford.edu
Austin Pineault
Structural Development and Mechanical Systems Integration
austin.pineault@stanford.edu
Andrew Milich
Avionics, Deployment, and Programming
amilich@stanford.edu
John Dean
Team member info.
Hannah Williams
Team member info.
Sruti Arulmani
Team member info.
Nate Simon
Parafoil and Aerodynamics
simonnj@stanford.edu
Brandon Vabre
Team member info.

Launch Vehicle Summary

The purpose of the Pegasus rocket is to demonstrate the feasibility of using a parafoil recovery system to create a controlled, directed recovery for a high-powered rocket from over 10,000 ft.

Payload Summary

The payload of this rocket is the active recovery system and its backup. The payload will be a parafoil deployed at apogee and controlled by two servos throughout descent.

Vehicle Criteria

Mission Statement

The Pegasus Rocket team is seeking to develop an efficient and reliable recovery system for high-powered rockets that utilizes a parafoil instead of a parachute.

Mission Success Criteria

The mission will be considered successful if the recovered rocket would be able to pass a L3 certification inspection. This means that if the rocket experiences excessive damage to the point that it could not be re-flown that day with a reloaded motor, then the recovery system will have failed. Another criteria is that the rocket will have landed within a 300ft radius of its original target landing space.

Constraints

1. Tripoli height ceiling of 16,800 ft
2. Rocket construction to be made using a “minimum of metallic parts” excepting those necessary for airframe integrity
3. Motor impulse to not exceed 10,240 N-s
4. Redundant avionics, wiring, and safe arm systems
5. Automated program for descent path
6. Manual back up control system for descent path
7. Back up recovery system consisting of main parachute
8. Vertical descent speed of 20 ft/s maximum upon landing
9. Budget

Propulsion System

The Cesaroni M1450 was chosen because it is commercially available, reloadable, complies with the Tripoli and California restrictions, keeps our rocket sub Mach-1, and should achieve a maximum height of 16,300 ft with the current mass estimates. Thus even if our mass budget increases, there will still be ample altitude to test the parafoil system.

The M1450 has an average thrust of 1500 N, a total impulse of 10000 N-s, a specific impulse of 210 s, a burn time of 6.9 s, and a maximum velocity of 300 m/s (Mach 0.9).

Motor Performance

image

image

image

image

Flight Characteristics

image

image

Avionics and Telemetry

APRS Transmission

The L1 rocket will not use an APRS transmitter.

In-Flight Tracking

In flight tracking will use a XBee Pro module and an Adafruit GPS receiver with a ceramic antena.

Parafoil System

Ground Station

The ARES-2 Ground Station will include two equivalently functional pieces of software for GUI or text based monitoring and control of the rocket. This includes, but is not limited to:

• A Processing GUI with in-flight instruments, real-time mapping, and graphical renderings of system status (such as velocity, vertical speed, or heading).
• A simple Python text-based monitoring application to continually log data and send basic commands (for example, ’turn right for 15 seconds’) to the rocket.
• Other simple applications to monitor range or other basic parameters.

File:Groundstation.png

caption A working demo of the GUI ground station.

Systems Integration and Testing

Major Vehicle Milestone Schedule

January 16: small scale test... blah blah blah

Risk Management

For this rocket using a parafoil recovery system creates most of the possible risks of having an unsuccessful flight. Our first risk is the parafoil not deploying properly. This could mean not emerging from the rocket, becoming tangled upon exit of the airframe, and becoming tangled in mid-air while opening. To mitigate the first issue, non-emergence, we are performing pre-launch date small scale tests to practice our system and amount of propellant needed to fully expel the parafoil. The second issue of becoming tangled upon exit we will also be performing small scale tests on prior to the full L3 rocket. This test will be performed again using a static run on the L3 to make sure we scaled it up properly. The final issue of becoming tangled while opening will also be examined through the small scale L1-L2 tests and should be mitigated depending on how the parafoil is folded and fit into the rocket airframe. The parafoil is also going to be contained in a freebag that will be pulled out by the drogue chute. This combination should also help prevent the other issues upon exit. In the event that all of this fails, the payload for the rocket is a parachute that is rigged to an altimeter. Upon too quick of a descent (aka parafoil mal-deployment) the parachute will deploy prematurely to slow the descent of the rocket to a safe speed of 20 <math>m/s</math>.
The second point of risk is when the rocket is descending while being controlled by the parafoil and the step motors. There is always a possibility of having strong winds above 10,000ft and gusts could cause major control issues for both the stepper motors and for the coded flight plan. Some fail-safes are put into place such as having overly robust stepper motors so that under larger-than-predicted forces the stepper motors will not fail. Another safe-guard are pre-written statements that are associated with the parachute. These safe-guards include too quick of a descent rate (parafoil failure), prolonged ascension after the rocket has reached apogee (in case of thermals or wind gusts forcing the parafoil upwards)

Budget

Our current total budget for Pegasus is $4000. Most of this will be going towards the purchases of our L3 components. Currently, our projected expenditures are below that budget limit. The largest budget “risk” would be testing expenses. It is easier to predict how much the L3 components are going to cost rather than the testing because extra tests might need to be run if we come upon unexpected problems, or are simply desirous of more testing before launching the L3.

Activity Plan

Budget

The overall Budget that the Pegasus team has is $4000. Currently our expenditure, predicted and already purchased, stands at $3160. An extra $200 can be expected to be spent on L1-L2 testing. The current budget break-down is as follows:

Motor	$710
Structural Components
Airframe	$200
Nosecone	$120
Fins	$80
Recovery System
Parafoil	$1200
Drogue	$66
Backup Recovery System
Parachute	$324
Recovery Accessories	$120
Avionics	$490
Testing Expenses	$400
	$3210