1tid.uio.no/kurs/fys2280/Manuals_2006/Payload.doc · Web view3.1 Encoder card. The encoder card...

Student Rocket Payload Manual


Kjetil Henninen and Amund Nylund of 16Last update: 2.8.2006


Introduction and Summary

The aim of this manual is to give a short guidance in how to make the payload ready for launch. The student rocket program is continuously improving and this manual has been updated according to these improvements. Last major improvement took place in June 2005, when we changed from L-band telemetry to S-band telemetry.

The payload structure is prefabricated by our mechanical staff. Some of the most essential electrical circuit boards are already made and mounted at the payload mounting plate.

The tasks of the Rocket Payload Group include:

o Get familiar with the technical and mechanical aspects of the student rocket payload.

o Get familiar with the operating of GSE (Grond Support Equipment)

o Test and install housekeeping board into the payload.

o Cooperate with the experiment group to integrate their sensor cards into the payload.

o Run balance test of the payload

o Run spin test of the payload

o Run final test of the payload in launch area (LA) before rocket motor can be mounted to the payload.

If there is time enough:

o Helping the Experimenters group etching and soldering printed circuit boards for measurements of temperature (or other sensors) in the rocket payload. See Appendix 1. For further information about the sensors, ask your instructor for the sensor documentation.

o Measure the power out of the transmitter card. See Appendix 2.

Sometimes separate group assignments are handed out with this manual.

The group has to elect one person to be the Payload Manager, who will be reporting payload status during pre-flight meeting and operate the payload during countdown and launch. The Payload Manager must be decided and reported to your instructor/group leader the day before launch.



1. Payload parts

The payload structure is about 640 mm long and consists of an alumina Ø70mm tube shaped body, a steel nose cone and a steel adapter for screwing the payload to the rocket motor. An alumina mounting plate for antennas and all the electronic circuit boards will be put into the body (see Figure 1).

Figure 1: Student Rocket Payload


Nose cone (Steel)

Body tube (Alumina)

Rocket motor adapter (Steel)

Umbilical mount

Alumina body tube

Battery mount

Encoder

Transmitter

Antennas

Mounting plate


2. Payload overview and general operation

The general information flow of the encoder is shown in Figure 2.

Figure 2: Encoder Information Flow

3. Connection of encoder and transmitter cards

Make sure that the transmitter and encoder card are connected as listed shown in Table 1 and 2 below.

Encoder connector Transmitter connector Wire colourTx + redG (ground) G (ground) blackM M white

Table 1: Encoder and transmitter connections

Power supply Encoder connector Wire colour+ 9 V B (battery +) red- 0 V G (ground -) black

Table 2: Power supply connections


Transmitter

PCM-Encoder

Ground Support Equipment (GSE)

Analogue

instrument (A0-A3)

Digital instrument (D1,D2)

Analogue instrument (A4-A7)

Umbilical

S-band antennas


3.1 Encoder cardThe encoder card has a power control circuit included. This power control circuit allow as to switch the power to the payload on and off via an umbilical cable.The encoder has 8 analogue and 2 digital input channels. The analogue and digital input channels will be used as table 3 shows:

Channel nr. PCM word InputJP A0 4 Analogue sensor 0 – Temperature Sensor PCBJP A1 5 Analogue sensor 1 – Temperature Sensor ExternalJP A2 6 Analogue sensor 2 – Magnetic Field SensorJP A3 7 Analogue sensor 3 – Absolute Pressure SensorJP A4 8 Analogue sensor 4 – Accelerometer – Z-axisJP A5 9 Analogue sensor 5 – Accelerometer – Y-axisJP A6 10 Analogue sensor 6 – Phototransistor JP A7 11 Analogue sensor 7 – Battery Voltage (or a sensor)JP D0 12 Digital sensor 0JP D1 13 Digital sensor 1 – LSB indicates lift-off

Table 3: Analogue and digital input channels on the encoder

The level of the input signals shall be 0-5V. Every signal at these different channels will be sampled and processed about 2285 times per second. But only one channel will be treated at the time (TDM – Time Division Multiplexing). Input impedance is 100kΩ. Input lowpass filter: 0-1000Hz.

3.2 Transmitter cardThe Transmitter is tuned to a frequency of 2279.5 MHz. It delivers about 750-800 mW of RF power. There is a power splitter at the card that has direct connection to two S-band antennas. Operating voltage is 6.5-12V, and the current about 450mA.

Figure 3: Transmitter card



Always use the dummy loads instead of antennas when testing the transmitter card. If the antennas are to be used you must have mounted the payload plate and antennas into the payload tube and tighten the screws. This is because the transmitter needs the correct impedance load at the output. NEVER power the transmitter card without proper load at the output. This will damage to the power amplifier circuit. Also make sure that the dummy loads or antenna mounts are tighten properly before you power the transmitter.

Further information about the about the transmitter and encoder will be given by your instructor. There will also be one copy of the technical documentation at the lab (USOC). Also see Appendix 2.

4. Making cable connections from encoder to sensors

All connections on sensors, encoder and transmitter use Micronnector connections. These connectors are suitable for student rockets because of the large forces on the structure during launch. All sensors have to be connected to the encoder. The wires must not be to short, but not to long either.

By use of a crimp tool and insert tool you will be able to make wire connectors for the circuit board sockets. Use AWG 26 wires, cut the appropriate length and remove approximately 2 mm of the isolation on both sides (see figure 4).

Figur 4: Crimp information (from data sheet)

Insert contact and prepare wire into indenter opening from side opposite the positioner. Wire and connector shall be crimped together. Squeeze handles together until ratchet releases. Handle will return to open position. Remove crimped contact and wire (See Figure 5).



Figure 5: Crimp Tool

Use a shoving tool to shove the crimped contact in the right position at the micronnector plug (Figure 6).

Figure 6: Shoving connector into female micronnector plug

It is important that the connector plugs has the same wire setup, because it have to follow the convention from the encoder. NOTE that the micronnector female plug is formed such that it only fits one way into the male plug. The convention of the analogue sensors at the encoder is shown in Table 4.

The wires to the micronnector shall be twisted two and two, Supply voltage (red wire) with Ground (black wire), and Signal (yellow or white wire) with Ground (Black wire). Also make sure that the connectors must be same in both ends, see Figure 7.


Female micronector plug


Pin nr.

Name Description and wire color

1 5 V Power supply, 5 V, to the analogue sensors. Red.

2 GND Ground. Twist with power supply. Black.3 GND Ground. Twist with signal. Black.4 Signal Output signal from sensor cards, 0 – 5 Volts.

Yellow or white.

Table 4: Connector pin overview

Figure 7: Complete connector cable from sensor to encoder

5. Mounting sensors to payload

On the other side of the payload plate there has been made space for 7 sensor cards. The sensor cards may be mounted on the payload plate in the positions that you like, but it is a good tip to start nearest the antennas and work your way down to near the encoder. NOTE! When you connect the cables to the encoder card you must follow the channel number listed in Table 3. This will ease the work for the experimenters and telemetry group when they do the telemetry data storage setup. If you use other sensors than mentioned in Table 3, make sure you inform the other groups about it. See Figure 8 for an example of a payload plate with 7 sensors assembled.

Figure 8: Payload plate with 7 sensors


1

2

4

3


A special nylon braided tape is used to tie up the wires to avoid getting loose during rocket flight. I addition superglue should be used, as the example in Figure 9. Make sure all wires are fastened properly before flight.

Figure 9: Sensor Circuit boards

6. Test of payload by use of GSE-panel

A black panel (Figure 10) called GSE (Ground Support Equipment)-panel will be connected to the payload both for full scale test of the payload and for the rocket lauch.

Figure 10: Ground Support Equipment

This GSE-panel has many functions: Supply the payload with External power. Charge the chargeable battery in the payload, Fast or Trickle. Switch between Internal (battery) and External power Check the battery power Check the condition of the different instruments in the payload Arm the payload

NOTE! Always switch on External power first (in case the battery is fully charged).The battery in the payload may be charged simultaneously as the payload is supplied by external power. The charging can be done either in Fast (1 hour) or Trickle mode



(10-12 hours). Maximum charging voltage is 12.45 V. The charging stops automatically at this level.After a while internal power can be selected and then the external power can be turned off. It’s always wise to switch back to external power when use of the battery is not necessary. Charging while running power will not work.

By use of two push buttons in upper right part of the panel you can step up and down in the menu for the display. On the display you will also be able to find the battery voltage.The voltage level of all word in the PCM-format will also be stepping in the menu.The levels starting with 0x are shown as hexadecimals.In word 11 in the PCM format the battery status is also shown. The value you read should be multiplying by 3.2 (due to maximum input level at 5V to the PCM encoder).

The ARM function shall only be used under countdown after internal power has been switch on and 30 seconds before launch of the rocket (according to countdown procedure).

7. Final assembling of the payload

NB! When you assemble the rocket DO NOT tight the screws, this will be done by the group leader.

NB! When you connect the nose to the body of the payload there are certain marks that should opposed to each other to make that the parts fit.

Always be careful when you insert or take out the payload instrumentation plate from the payload tube.

Make sure the antennas are tightening properly before you switch the payload on.

8. Balancing the payload

When all sensors and wires are assembled on the payload instrumentation plate, the payload has to be balanced. This is because centre of mass needs to be along the centre line of the payload. We use the balancing bench in Payload Checkout to rotate the payload and put in extra weight inside the payload tube near the motor adapter, see Figure 11 and 12. Make sure the extra weights are properly fastened. Use strong epoxy if necessary. Your instructor will assist you with this task.



Figure 11: Balancing bench Figur 12: Extra weights inside payload tube

9. Final testing of payload

Before your Payload Manager can report ready for flight, you have to do 2 important tests of the payload:

9.1 Spin testContact the Telemetry group(s) and Experimenters group and confirm that we are ready to run spin test of the payload. Bring the payload and GSE-panel to the Clean Room. Make sure you also bring an extra power cable and umbraco tools. Assemble the Student Rocket payload adapter to the spin bench. Use the GSE-panel to switch the payload on and off. NOTE! Make sure you switch the payload on internal power and remove the GSE-panel before you start spinning. Have contact with the other groups and spin the payload up to maximum level. Redo the spin testing if necessary. Your instructor will assist you with this task. Figure 13 shows a payload on the spin bench in Clean Room.



Figure 13: Student Rocket Payload on spin bench in Clean Room

9.2 Test of payload on padBring the payload and the GSE-panel to the Launch Area. NOTE! If there are rocket motors in the launch area, some areas will be restricted. Your instructor will assist you with the tasks in the launch area. The first task will be to take out the umbilical cable from a small hut near the launcher and bring it to the launcher. Return to Block House and prepare the GSE-panel near the Intercom and Go/NoGo-panel. Then you have to attach a dummy rocket motor to the payload, and bring it to the pad. Put the Student Rocket on the launcher and connect the umbilical cable. Then you return to Block House and report to Telemetry groups and Experimenters group that the payload is about to be tested. Turn on the payload and make sure it is healthy. When the other groups are satisfied, turn off the payload and we are ready for flight. NOTE! Make sure you bring the umbilical cable inside the hut over night in case of bad weather.

NB! This is the last payload test before countdown, so make sure you test the payload both on external and internal power, and that the battery is fully charged before you end the test.

Figure 14: Final testing of payload with dummy motor on launch pad



Appendix 1

A1.1 Construction of payload sensor cards

A housekeeping circuit card (sensor card) shall be made from scratch. This includes etching and soldering in accordance to pre-designed circuit layout sketch.

The group will be handed a Printed Circuit Board (PCB)-laminate. The laminate, (with copper on both sides, but no pattern yet) is coated with a UV-sensitive photo-resist. The track pattern is imaged onto each side of the PCB, using photo plots and UV light. The photo-resist is developed; leaving photo-resist only where copper is required. The laminates are put in acid, to etch away needless copper, forming the track pattern. The bare copper PCB with tracks and pads is silks screened with a solder mask. The tracks are cleaned with red spirit. Ask your instructor for the procedure “Etcing of Printed Circuit Boards (PCB)” if necessary.

Now the card should be ready for drilling of holes. Use 3.2 mm drill (at the mechanical workshop) for the 4 mounting holes. For the rest of the holes a 0.7 mm drill is recommended (but 0.8 mm will also do, and some holes require a 1.0 mm drill). For this precision work you can use a mini-drill-machine.

The vias can either be made by use of a pressure tool that forces the via connector through the circuit board, or simply by soldering a short wire between the top and bottom of the card. The last method is most common, but if the pressure tool (see Figure A1.1) are used it must be handled very carefully.

Figure A1.1: Pressure Tool

Keep in mind that all the vias are made, must also be soldered from both sides of the circuit board.

A1.2 Soldering of housekeeping circuit card

Now you can start to surface solder all components onto the PCB.The temperature circuit surface sheet in Figure A1.2 tells you which components you should surface solder onto the print card. All the parts are listed in Table A1 below.



Make sure you have all of the components you need. NOTE! Make sure you get the Op-amp the correct way. Ask your instructor if you are in doubt.

Nomination

Components Amount Ok?

R2, R3 Resistance 1kΩ 2R1, R4 Resistance 3,9 kΩ 2OP1 Op-amp 296GS 1TEMP1 Temp. sensor LM35DZ 1C1 Capacitance 0,1uF (on bottom side) 1P1, P2, P3 Micronector sockets (4 ways) 3Table A1: Temperature circuit card, check-list.

You will be given a quick soldering lesson. NB! Always ground yourselves with a chain bracelet to avoid static electricity. Static electricity can cause damage to the power control card.

The group leaders will be together for guidance during the whole process.

When you have finished soldering the components you must test the printed circuit board. NB! Do not do this without assistance form a group leader.

If the circuit card doesn’t work, you will have to fault detect with a multimetre.

Figure A1.2: Temperature sensor PCB print

Test the card separate and use a hair dryer to heat up the 2 sensors.When the card is found ok it can be mounted at the payload instrumentation plate.Use 3mm spacers and M10x3 screws.



Appendix 2

A2.1 Stand alone test procedure for payload transmitter card

Note! Always use a 50 Ohm RF load before switching the transmitter on. Not doing so will wreck the transmitter.

Use a suitable Laboratory power supply and a couple of wires, preferably black and red. Black will be the negative lead and red the positive.

1. Connect Positive (+) wire to transmitter terminal 42. Connect Negative (-) wire to transmitter terminal 23. Make sure you have the 50 RF loads connected to the outputs of the

transmitter4. Make sure the voltage supply is set to 9V before powering on. 5. When the transmitter is switched on the LED will light up. 6. Use a spectrum analyser to verify the correct frequency; 2.279,5 MHz.

Figure A2.1: 50 ohm RF dummy loads

A2.2 Measuring the output power of the transmitter

Using a Bird RF power meter to measure output power of the transmitter is a good way to check if the transmitter delivers the enough RF power to ensure good signal quality at the receiver station. It is highly recommended that an experienced technician assist you in these measurements.

Figure A2.2: Bird RF Power meter

NB! To prevent wrecking the transmitter it is highly recommended that applied power to transmitter does not exceed 9V at the time the transmitter is switched on and the bird power meter is attached to one of the output ports of the transmitter. It is very important to not use a fully charged NiMh Battery, the one used in the payload, for



testing purposes. This includes switching the payload from off state straight to internal power when measuring RF power.

A2.3 End notesHandling

Take care to handle the transmitter carefully and take ESD precautions. Use a grounded wrist strap when handling the device and mounting it into the payload.

Applying wrong polarity to the transmitter power terminal destroys the transmitter.

While testing the payload Always make sure to have a 50ohm RF dummy load connected each of the

RF output ports when testing the payload. Never switch on the payload when the transmitter is connected to the

antennas and the payload deckplate is not securely fastened inside the rocket skin.

Anomalies The Red light on the transmitter indicates that the transmitter is functioning

properly If the light fails to light up when applying power to the terminals it is a sign that

the power amplifier needs to be replaced. Be sure to disconnect power from the transmitter as soon as possible when

you detect that the LED fails to light up.


1tid.uio.no/kurs/fys2280/Manuals_2006/Payload.doc · Web view3.1 Encoder card. The encoder card...

Documents

Transcript of 1tid.uio.no/kurs/fys2280/Manuals_2006/Payload.doc · Web view3.1 Encoder card. The encoder card...