BPASA

  Boris and Paul's Aeronautics
and Space Administration

Paul's TARC team ranks 17th in the 2015 finals out of 700 teams in the USA!

 

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Rocketflite igniter/ematch flights and tests
Rocketflite ematch tests featured in the May/June 2009 issue of Sport Rocketry magazine

Please see www.rocketflite.com for more information

2012 Update:    

Rocketflite introduces the new CF (ClusterFire) pyrogen

At the start of 2012, Rocketflite came out with a new product, CF (ClusterFire) pyrogen, compatible with its established line of MF ematch wires. This new CF system has the benefits of using their lower current MF wires with a pyrogen that burns almost as long as their excellent ML igniters.

In 2012, I used the new CF (ClusterFire) ematches:
In 28 clustered flights, successfully firing 191 of 192 motors loaded - 99.5% success rate
Also used CF igniters to fire all 18 deployment ejection events with no failures in 2012

Preparing Rocketflite Igniters and Ematches

The process is easy, see instructions and pictures in the yellow side bar further down this page for making ML (MagneLite) igniters and MF (MagFire) ematches.

To prepare the new CF (ClusterFire) igniters, dip MF wire in CF pyrogen and let dry. This process looks like the description for ML below, a simple one-dip process.

All Rocketflite igniter and ematch wires already have the nichrome bridge wire soldered in place, and their long leads eliminate whip clips. Wires are available a variety of sizes to work well with different sized motors and ejection applications. Please note that both wires and dip kits must be purchased to make Rocketflite igniters and ematches.

Suggested Techniques

> Clusters should be fired by a strong 12V+ ignition system with a relay
>
Use
secure and direct wiring no whip clips
> Rocketflite CF/ML/MF igniters can be used in parallel for up to approximately 8 engines
> Combine series and parallel CF or MFs for clusters to reduce ignition current load.
   Have fired 30 CF's and MFs at once, 60+ should be possible.

Also consider:
> Sand propellant slots to remove any propellant oxidation
> May accelerate AP motor ignition by placing a small amount of ML pyrogen at the top of an
   engines propellant slot. I have had good results with near instant ignitions using about 2x
   as much pyrogen as would be used on an igniter.

Series + Parallel wiring of igniters/ematches

For flights firing 6+ igniters I normally wire igniters in series strings of 2 or 3 and then combine these in as many parallel sets as needed. Combining series and parallel wiring of igniters/ematches can greatly reduce the current load during a cluster launch.

Caution: Conduct thorough ground tests of any new technique.
See test details further down this page.

Step 1: Wire CF or MF ematches in series strings of 2 or 3 (picture 2).
Step 2: Tape over connections between wires to prevent short circuits (as shown in picture 3). 
Step 3: Check these strings for continuity. Each ematch should have a resistance between 0.8 and 1.2 ohms. This slight variation is not a concern. So a series string of 2 wires would have 2x this resistance (1.6 to 2.4 ohms) and a series string of 3 wires would be 3x (2.4 to 3.6 ohms).

Note: This increased resistance is the reason to use this method, as resistance goes up,
current goes down. Ohm's Law: Volts = Amps x Resistance

Step 4: For larger clusters, wire as many of these series strings as necessary in parallel to fire all motors (see here and here).

Using series wiring for MF/CFs greatly reduces the current load on a 12V launch system. Ignoring launch system voltage sag and other transient effects for simplicity, comparing approximate current loads:

ML igniters, 3x in parallel: 1ohm each, cluster total 0.33ohm, = 36A load
MF/CF ematches, 3x in series: 0.8ohm each, cluster total 2.4ohms, = 5A load

This 7x reduction in current load greatly reduces the demand placed on the launch system and - as long as plenty of voltage is available - increases the chances of quickly firing all ematches and motors.



photo by Tony Vincent
picture 1


picture 2


picture 3


Making Rocketflite ML (Magnelite) igniters:

Step 1: Dip ML wire into ML pyrogen.


Step 2: Let dry for one hour.


Igniters are ready to use for motor ignition.


Making Rocketflite MF
(MagFire) ematches:

Step 1: Dip MF wire in MF pyrogen.

Step 2: Let dry for one hour.

Step 3: Dip in MF sealant.
(Included in MF kit)

Step 4: Let dry for one hour.

Ematches are ready to use for ejection charges and motor ignition.

Original 2008 tests:

Extensive ground and flight testing of prototype Rocketflite MF (Magfire) ematches

Bottom line for all flight tests in 2008:
99% reliability firing AP and BP engines and ejection charges

Please see www.rocketflite.com for more information

In 2007 I used Rocketflite (ML) MagneLite igniters to light all cluster flights, and had 99% reliability igniting engines.

Flew a total of 16 cluster flights in 2007, igniting between 3 and 8 engines at the pad. The most  complex flight the VooDoo Daddy's successful flight on 16 D engines in 3 stages. (picture 1)

Method I used for reliably clustering up to 8 engines:
>  Use Rocketflite ML (Magnelite) igniters check wire resistance when making igniters
>  Secure parallel wiring, all igniter leads twisted directly together and then twisted around pad
    power clips (no whip clips, eliminating many electrical failure points)
> Strong 12V ignition system with a relay at the pad
> Sand propellant slots remove oxidation


First Flight Tests 2008

In order to fire many engines in clusters it was necessary to minimize ignition current load while maintaining reliability. Rocketflite had just released their (MF) Magfire ematches intended for firing BP ejection charges.

On 1/12/08 used the new MF ematches, wired 3 in series, to successfully launch the Applewhite 10 saucer three times on 3x D11-P engines (pictures 2 and 3).

Testing Overview

Tests of Rocketflite MF prototype ematches used:
> Currently available MF pyrogen.
> Nichrome wire is soldered to the lead wires.

Tests experimented with:
> What battery and electronics are used to fire the MFs.
> What the MFs are used to ignite.
> Variations on how much MF pyrogen dip is applied.
> Slight variations on details of the nichrome wire.

 Ground Tests

Test: Can MFs Ignite AP Engines?    YES

> Ground test fired a variety of AeroTech reloads for the RMS 29mm 40-120 engine system:
   3 Black Jacks, 3 Redlines, 2 Blue Thunders, and 5 White Lightnings.
> For every test where the MF ematch head was in direct contact with the propellant,
   the engine fired on the first attempt.
> The one ignition failure was due to an intentionally tiny ematch head being placed so high in the
   G71-4R cavity that the head was entirely in the delay cavity above the propellant.

Conclusions:
> MFs can reliably ignite small AP engines of multiple propellant types.
> MFs (or any other igniter) need to match the 5/8 pyrogen length used by ATs igniters to avoid the
   risk that a smaller ematch/igniter head could pass above the propellant grain in some 29mm
   engines.

Test: Firing MFs with Altimeters and Timers:
YES   if firing circuit is battery powered
NO  if CD (Capacitive Discharge) firing circuit

> For all altimeter tests the MF ematch heads were placed in small 0.17 ID tubes to simulate
   containment effects present in normal use.

Number of MF ematches that could be fired

Device

Battery

Max Parallel

Max Series

Perfectflite MT3G Timer

Ray-O-Vac 9V Alkaline

1

2

Perfectflite MT3G Timer

GP 170 8.4V NiMH

2

3

G-Wiz LCX Flight Computer

1x GP 170 8.4V NiMH

None

None

G-Wiz LCX Flight Computer

2x GP 170 8.4V NiMH

1

2

Perfectflite Hi-Alt 45K

GP 170 8.4V NiMH

2

1

Perfectflite MAWD

GP 170 8.4V NiMH

None

None

Perfectflite MT3G Timer

Duracell 9V Alkaline

4

4

I used the Perfectflite Hi-Alt 45K altimeter and MF ematches for all flight ejection charges in 2008 and fired all 15 charges successfully.

Can MFs be Fired in LARGE Groups?   OH YES !


The following ground tests used a 12V launch ignition system with a 22Ah lead acid battery, 40A relay and 16awg wire.
 

Configuration

Result

Total Resistance (ohms)

MF Series

Current Load  *

ML Parallel

Current Load  *

3 in series

All Fired

2.4

5A

36A

4 in series

All Fired

3.2

3.8A

48A

6 in series

All Fired

4.8

2.5A

72A

7 in series

5 of 7 fired

5.5

2.2A

84A

6 in series

All Fired

4.8

2.5A

72A

18 total = 6 parallel strings of 3 in series

All Fired

0.4

30A

216A

8 total = 2 parallel strings of 4 in series

All Fired

1.6

7.5A

96A

 

 

 

 

 

 

 

* Comparison of approximate current loads with a strong 12V source, ignoring transient effects for simplicity. MF typical resistance 0.8 ohm, ML typical resistance 1.0 ohm.

Some MFs that were not contained in tubes when fired burned part, but not all of their pyrogen. MFs ignite their pyrogen so quickly that a modest level of containment improves their ability to completely burn their pyrogen. Never saw partial pyrogen burn in any MF fired in a small 0.17 ID tube, always all or nothing. Modest containment would normally be present by design in ejection charges or 29mm or smaller engines.

Conclusions:

A strong 12V source can:
> Fire a single series string of 6 MFs.
> Fire multiple series strings of 3 or 4 MFs, when those strings are then connected in parallel.

> Longer series strings use less current because their resistance gets higher. However, if the string
   gets too long reliability becomes a problem.
> MFs ignite their pyrogen so quickly that a modest level of containment improves their ability to
   completely burn their pyrogen.

Flight Tests: Clusters and Deployments using Rocketflite MF Ematches

At the 4/19/08 CMASS launch in Amesbury, MA: Flight 1: the TOGinator Loaded with 26x D11-P engines. At 468 Ns total impulse,
this was a mid-
I
power BP liftoff.

The MF ematches were set up in 8 strings of 3 MFs in series plus 1 string of 2 MFs in series.
Confirmed resistance / continuity before connecting the 9 series strings of MFs in parallel.

Comparing ignition system current load, ignoring transient effects for simplicity: For this flight using MFs in series strings of 2 or 3, the total launch system load was about 48A. Using a typical igniter like the Rocketflite ML all in parallel, the igniter system would attempt to draw about 300A. Also used MFs to fire the two ejection charges using a Perfectflite HA45K altimeter.

The liftoff was dramatic, with the jets of flame spread wide, big cloud of smoke, and every engine firing! The rocket lifted off quickly due to the 160 lb thrust spike at the beginning of the engine burn.

All 26 engines fired, as did both ejection charges.

 
The TOGinator getting prepped and then all wired up at the pad about to fire 26x D11-P engines with a parallel and series setup of
Rocketflite MF ematches. Lifting off on a fan of flame and smoke.
Thanks to Jim Flis for the flight photo and the many cool FlisKits that inspired this rocket.


Flight 2: The Ultimate FireBall

Loaded with a 7x AP engine cluster made up of AeroTech 29mm engines: 4x F40Ws and 3x G77Rs.
Total impulse for the flight was 635 Ns, full
I
power using 29mm engines.
The 4 diameter rocket was 7.5 ft tall and 9.3 lbs at liftoff.


                                                                                                                                            photo Guillaume Meriaux
The Ultimate FireBall wired with a parallel and series setup of Rocketflite MF prototype ematches firing 7x 29mm AP engines.

All engines fired, sending the rocket soaring on a cool looking rose colored flame with a white core, due to the red Gs and white Fs. Both ejection charges fired for good dual deployment recovery on a Top Flight Recovery 5 ft Crossfire chute.

MF ematches fired the engines set up in 2 series strings of 2 MFs and 1 series string of 3 MFs, and also fired the two ejection charges.
The MFs in series only required about 20A, compared to a parallel igniter load of about 80A.

Rocketflite prototype MF ematches made it possible to fire everything 100% successfully with one type of ematch:
7 AP engines, 26 BP engines and 4 ejection charges.


Tests: Instant AP ignition
Using AT 29mm G64W engines, experimented with adding Rocketflite ML pyrogen inside the top of the propellant slot, about 2x what would go on an igniter, and successfully achieved near instant engine ignition. For these tests lightly sanded inside the propellant slot first.

Evaluated the speed of ignition by attaching an LED light to the pad ignition circuit in parallel with the MF ematch and video recording the launches. By counting video frames, determined that the added ML pyrogen had the G64s up to pressure within 0.1 second. Without extra help a G64 typically comes up to pressure in 0.3 to 0.5 seconds.

The method I prefer to boost AP ignition speed is Rocketflite ML pyrogen, as that poses the least risk of over pressurizing the engine.

Now I was ready to fire mixed engine types in clusters with confidence that all engines would be firing before the rocket started to rise up the launch rod.      


J and K Impulse Clusters
At NERRF 4 used MFs with 100% success to fire 12 BP engines, 6 ejection charges and 11 AP 29mm engines

including:
> VooDoo Daddy twice: including Paul's first cluster
> Apollo Saturn V twice: first for my L2, second a K impulse cluster
> Ultimate FireBall on a 7x G cluster

The Saturn V went up fast on a 5 engine K impulse cluster, with a Cesaroni K-445 and 4x G64's. Used a Rocketflite ML igniter for the center motor and MF igniters in the G64's. Worked like a charm, kicking all five engines instantly for a hard long thrust to 3,372 ft. Total impulse 2095 Ns.

The Ultimate FireBall went up on a J powered cluster of 7x RoadRunner G80-10s, ignited by MF's. Fast smoky liftoff to 2462 ft.


               Apollo Saturn V cluster                          Ultimate FireBall prepped with MF ematches..................and lifting off fast                   .
.


At CMASS on 10/4/08 the FlisKits inspired TOGinator flew again. The upper body had been rebuilt and also had gained four more engine tubes and was now prepped to fly with a 30 engine J powered cluster of 3x G71R + 12x E9 + 15x D11-P engines.


.                                                                                                                                          photo Doug Gardei                            photo Doug Gardei
Series strings of 3 MF ematches ready to be inserted into rocket engines. The TOGinator wired up with 30 MF ematches set up in series and parallel. At the pad another wire was run to the upper engines.

The flight lifted off on a wide fan of yellow flames cut through with three longer spikes of red, soaring to 1260 feet, mid-afternoon on a clear cool day. This was the flight I had been working up to for nearly a year.

The propellant slots in the Redlines were lightly sanded, and there was a small amount of Rocketflite ML pyrogen at the top of the slots, causing them to come up to pressure at the same time as the BP engines.

The MF's fired in every engine and both ejection charges. Three of the D engines did not ignite because (I discovered later) there was clay in the nozzles covering the BP, so 27 engines fired. Prepped with 910 Ns, fired 856 Ns, still a mid J powered cluster of AP and BP engines.

MF ematches fired the engines set up in 8 series strings of 3 MFs and 3 series string of 2 MFs wired together in parallel, and also fired the two ejection charges. The 30 MFs in series/parallel only required about 65A from the launch system, compared to a parallel igniter setup which would attempt to draw about 360A.

At a later launch, the 10" Cluster Saucer got a good liftoff fired by MF's on the same 3x D11-P engines that had not fired in the TOGinator flight, after the clay in their nozzles had been carefully removed.


2008 Flight Results

As a practical and fun way to field test Rocketflites 26awg prototype MF ematches, I used them for every ejection charge, BP engine, and 29mm AP engine flown in 2008. Results using Rocketflite 26awg MF ematches:

> Ejection charges: 15 attempts / 15 successful

> 148 engine ignition attempts, of these:
* 142 fired on the first attempt
* 3 had clay covering the BP in the nozzle and were fired later after this was removed
* 1 was an old stubborn F21W, which confirms that a hard to light engine likes a long firing igniter
* 2 were engines in good condition that did not fire due to apparent failure of the MF ematch

Engine ignitions (BP and AP): 144 attempts with engines in good condition / 142 successes.

Bottom line, Rocketflite prototype MF ematches provided 99% reliability in the field.
The MF ematches achieved this performance while requiring much less current than typical igniters.


Lessons learned firing MF ematches

A single MF can be fired by one AA alkaline 1.5 volt battery, allowing the most basic launch system to fire anything up to a 29mm AP engine.

Small clusters of MFs may be fired by 6V to 9V ignition systems. Ground testing an ignition system is a good idea prior to flying clusters. 

Large clusters should be fired by a strong 12V ignition system with a relay.

  Rocketflite ML igniters or MF ematches can be used in parallel for up to approximately 8 engines

  Combine series and parallel MFs for clusters to reduce ignition current load. Have fired 26-30 MFs at once, 60+ should be possible.

  Secure wiring no whip clips

 

Also consider:

  Sand propellant slots remove oxidation

  May accelerate ignition with ML pyrogen at the top of an AP engines propellant slot
 


Disclaimer
Please note that I do not speak for or represent Rocketflite. Rocketflite has sent me supplies for tests.
What I have written describes my tests and projects as an individual rocketeer.

Please see www.rocketflite.com for more information.