Hypertek Service Bulletins
HyperTEK HyEFX J Motors – Service Bulletin # 2
Though HyperTEK HyEFX J Motors successfully passed beta and TMT testing, there have been
problems reported with certain combinations, resulting in damage to the injector bell. The
combination where this phenomenon has been observed is when using the 0.172” orifice
with HyEFX J grains. This can occur with either the 440cc or the 835cc tank, and it
appears that the combination of higher flame temperature with the “buzzy” nature
of this setup results in the flame front impinging on the injector face. This setup was
tested and flown many times without problems. However, since then there have been sporadic
reports of damage to the bells.
Upon being made aware of the problem, Cesaroni Technology Inc. asked that these
combinations not be used while the problem was investigated. (27 July 2001 Service
Bulletin) Several test firings and metallurgical analysis have since been done. These
tests left us with two options. Those options were to decertify the combination, or to
modify the J bell so that it was better able to withstand the environment created by the
HyEFX grains. The modifications are not minor however.
Given these options, we have decided on the following course of action.
In keeping with our effort to offer the widest and safest range of hybrid rocket products,
Cesaroni Technology Inc. is going to produce a second line of J Bells, specifically for
those who want to fly the 440 or 835-172-J-FX combination. The new bell is part number
HT-J2B-IB, and carries an MSRP of USD$67.50. The changes to the bell include the addition
of a stainless steel flame shield to the inner injector face, which has been shown to
eliminate the problem in all testing to date. There is no change to the performance of the
system.
Cesaroni Technology Inc. will replace J bells that have been damaged by the 835-172-J-FX
combination. Bells being replaced under this warranty program must be returned to the
dealer by 31 October 2001. We will ship replacements to the dealer you purchased them
from. We expect bells to be ready for shipment to dealers by 31 October 2001.
In addition, CTI is offering a factory-direct service for HyperTEK fliers who already own
a J bell and wish to have it upgraded. You may send your J bell to CTI freight prepaid
along with a check or money order for USD$35.00, and we will refurbish and upgrade it then
return it to you freight prepaid.
Anyone flying the 440-172-J-FX or 835-172-J-FX combination must use the lined bell from
today forward. The 835-172-J-FX and 440-172-J-FX combinations when used with a standard
bell will not be covered under warranty after 31 October 2001. It is to be considered an
uncertified combination. The 440-172-J-FX and 835-172-J-FX combinations may be used with
the lined bell only.
A reminder – the 835-125-J-FX combination is not TMT certified and has never been TMT
certified for use. This combination should not be used and is not covered by the product
warranty.
The standard J bell will still be offered with complete motor systems and as an accessory
item, since there are many existing and new combinations available to be flown that will
benefit from the cost advantage of the original design.
We thank our dealers and loyal HyperTEK fliers for your support, and wish you many
exciting HyperTEK flights in the future.
Cesaroni Technology Inc.
3 October 2001
SERVICE BULLETIN - J MOTOR SYSTEMS
There have been reports of HyperTEK® bells being damaged when fired in the combination of
a HyEFX J fuel grain and 0.172” or 0.125" diameter orifice, when used with the
835 or 440 cc nitrous oxide tank. Though this motor configuration successfully completed
TMT testing and beta testing, there appears to be the potential for damage to the J bells.
Cesaroni Technology Inc. is aware of the problem and actively working on a solution.
Until such time the solution has completed testing we ask the HyperTEK users do not use
the following motor combinations:
835-172-J-FX
440-172-J-FX (N.B. This combination has not been TMT certified)
835-125-J-FX (N.B. This combination has not been TMT certified)
Testing of the motors is ongoing and a resolution to this issue will be published as soon
as possible.
Cesaroni Technology Inc.
27 July 2001
Subject: Accelerometer Anomalies.
Recently, there have been reports of hybrid rocket recovery failures using a accelerometer
based system. Hybrid motors can produce significant vibration during operation. It is
theorized that the dynamic accelerations associated with these vibrations can be
integrated by the accelerometer based recovery system. The magnitude of this condition can
vary depending on the type of motor, vehicle mass and design as well as the flight
profile. If this is in fact the case, an accelerometer-based device may not compute an
apogee solution at the correct time. This could cause a late or no deploy situation.
Until recently this condition has only been reported with one particular brand of recovery
system that is manufactured in Europe. The Hypertek M has been flown successfully on a
domestic accelerometer system known as the Altacc without problems. Altaccs are routinely
flown with J through L motors as well and Cesaroni Technology has not received any reports
of recovery problems.
On June 24th, a Hypertek M powered rocket was flow with redundant Altacc systems and both
systems failed to fire deployment charges. The systems were verified to be armed prior to
launch. These units were also flown successfully in a different rocket with an Aerotech
M1419 two days prior. It is important to point that the failed installation included an
unusually long wiring harness on the remote arming boards. DaveyFire M28F fuse heads* were
used in the recovery charges. These fuse heads have an all fire current of 1.0 amp @ 10ms
vs. 0.4 amps @ 10ms for the type B fuse head**. Since all power and arm/fire current is
fed through the harness, contact switches and connectors, it is suspected that the firing
output was de-rated to a level less than what would be required to fire a type F fuse
head(s). When using any electric match, it is very important to fully understand their
electrical characteristics before using them with your recovery and/or on-board ignition
systems. In other words the redundant failure may not be an integration error, but may be
traced to system installation.
Cesaroni Technology is working with the manufacturers of these devices to identify and
resolve these issues. blacksky is replicating the extended harness/28F configuration for
bench testing. CTI will be installing an Altacc on our dynamic shaker table and exposing
it to various hybrid motor signatures for analysis. CTI has also initiated discussions
with AED in this regard.
In the interim we recommend that any large hybrid powered rockets that are using
accelerometer based electronics incorporate a backup device such as a timer, barometer or
magnetometer etc. If there are any questions regarding backup implementation, please
contact blacksky or Cesaroni Technology for details.
* Daveyfire M28F fuseheads are also marketed as HiRMI Mini and Standard electric matches
by blacksky Corporation.
** Daveyfire M28B fuseheads are also marketed as HIRMI Sensitive electric matches by
blacksky Corporation.
