Up Battery Precautions Wt + Drag Electric Jet Flight

Safety Issues

LiPo Storage

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

•  More Pilot Proficiency Training 

•  Pilot Proficiency Training

•  Flying Surface Spot Repair  

•  Wing Ding Repair  

•  Color Matching  

•  Glue Blemishes on the Paint  

•  BVM Fine Finish Restoration Kit

•  Speed Runs in Perspective  (September 2010)

See "Flight Safety" Article

 

 To keep the balance tab out of the EVF blades on models with bifurcated inlet ducts, this Velcro system also allows easy release of the balance tabs for charging.

Apply a 2-1/2" strip of adhesive backed prickly Velcro to the battery pack, then use a 2" length of fuzzy Velcro to retain the balance wire/tab.


 

LiPo Batteries
Protect Your Investment

    It is simply a relationship between chemistry and temperature.  To protect your investment, it is best to store your LiPo batteries at 3.86 volts per cells.  This is especially important in the summer time when car/trailer temperatures can reach 130° F or more at mid day.  The chemical activity of a fully charged battery at these elevated temps can really challenge the cycle life of LiPo’s.

   So, if you are not going to fly soon, store the batteries at the 3.86 volts at normal room temperatures and you should enjoy your investment to the maximum.

   Some chargers have the “Storage Charge” feature.  If yours does not, simply run the batteries in your EVF powered models until they are close to the optimum storage voltage.

 LiPo Storage

Note:  The latest charger from FMA – the Cellpro Power Lab 8 and the TunderPower 2010 have this “Storage Charge” feature.

see Cellpro Power Lab 8


Thrust Tube Attachment

(09/28/2010)


EVF Fan Unit

(08/19/2010)

DO NOT allow paint to get on to the rotor blades.  This could cause an out of balance condition that could cause the rotor to vibrate and possibly come loose.


EVF Tailpipe

(12/09/2008)

The original BVM Electra jets have hundreds of flights on the original tailpipes taped together per the instructions. We have heard of a few in-the field that have had the taped seams open up. This will cause a very noticeable loss of thrust. If you experience noticeable loss of thrust, land as soon as practical. Check the tailpipe seam and batteries of course.

To repair the tailpipe, remove it, strip away the tape and clean the tape residue off with 3M Adhesive Cleaner #08984 (available at auto paint supply stores). Then rebuild the tailpipe as per the instructions.


Always check the voltage of the Saddle Cells and Booster packs just before flight.

Our practice is to check them prior to installing the packs in the model at the field.  It is essential that the fully charged voltage reads within .10V for the Saddle Cells and if a Booster pack is used, the corresponding voltage for a 2 cell pack.

The total variance should be .10 volts or less.

i.e.
        5s pack   Volts = 21.00 +/- .05
        6s pack   Volts = 25.20 +/- .05
        2s pack   Volts = 8.4     +/- .05

 

Note:
    Following this procedure is very important to protect your investment in the batteries and your model.  An out of balance mix of batteries will damage them and cause a sudden loss of thrust early in the flight.  BVM uses the Power Meter from E-Flite, a division of Horizon Hobbies.


Aluminum Servo Arm Procedure


Adapting a BVM Jet Case to carry an Electra Jet


Converting Early BVM D/F Jets To EVF Power

The Electric VioFan is a drop-in replacement for the piston powered Viojett, so converting these models to EVF power is relatively simple.

The best candidates for the conversion are the F-86 Sabre, F-16, Maverick (and Pro version), Aggressor III, and the Ultra Viper because the space available and access to the batteries is adequate.  The very early Viper and Aggressor I's and II's have limited space and access but can accept some battery configurations.

Please keep in mind that the EVF power exceeds that of the DF Viojett.  Therefore, the structural integrity of the very early designs combined with aging glue joints must be a consideration in your decision to convert. 

This information is not intended to be a thorough step-by-step instruction manual on each conversion but rather a few guidelines on how to accomplish.  Experienced modelers can handle it.

Since the model you are considering for the conversion may be new in the box partially built, or one that has been completed and flown with D/F power, the following guide lines must be applied accordingly.

These guide lines will assume that the model has been built and flown.

•    Remove the Viojett, Tuned pipe, fuel tanks, and plumbing.

•    Remove the F/G Tailpipe with pipe hanger.

•    Remove the throttle and mixture control servos and linkages and their mounts.

•    Thoroughly clean any fuel reside from the inside of the fuse and check all glue joints for security.

•    The original non-"Hush kit" treated inlets do not require any modification.  If the model has the "Hush kit" canisters, it is best to remove the inlets and install fresh ones.  BVM can provide these parts.

Note:  It is likely that the epoxy paste seals on the Hush kit canisters no longer provide a perfect seal.  An air leak in the canisters will severely interrupt the inlet flow and cause a noticeable loss of thrust.

•    Acquire the appropriate Mylar thrust tube for your particular model.

•    Install the EVF unit per original mounting system.

•    Install the thrust tube per its instructions.

•    Read EVF instructions.

•    See many posts on this site for more Hints + Tips on successful EVF operations.

•    Install the batteries.

•    The Center of Gravity and control travels remain the same as published in the original kit.


Electric Jet Flight

Experienced EVF pilots know how to fuss over their batteries by keeping records of flight times, temperatures, recharge capacity and total number of cycles etc.

Even with this close scrutiny a cell can occasionally deteriorate.  Your testing equipment may not pick it up. But should you notice that during a flight, the power just doesn't seem right, i.e. what you have gotten use to, land as soon as possible.

The deteriorating pack will begin to put extra demand on the other Saddle CellTM.


WARNING

Immediately after each flight, disconnect the fan power batteries from the ESC. If this procedure is not followed, the ESC will continue to draw a small amount of current from the batteries eventually depleting them below minimum voltage and possibly ruin the entire set of packs.

Connecting the Batteries to the ESC

It is a simple operation, but done incorrectly, can be harmful to the batteries.

        The R/C link must be active (on) and the throttle and trim lever in the full aft (off) position. For the first operation of a new setup, be certain that the throttle channel is not reversed. The E.S.C. is set correctly at BVM and test run so it is not reversed.
   Connect the Saddle Cells™ to the two male legs of the "Y" harness. A slight spark is going to occur during the connecting process (to E.S.C.) so be prepared for it.

        Observe the female end of the "Y" harness Dean's connector. It is best to aim the brass male pins at the plastic side of the positive and negative receptacles.

        The connection should be a smooth and deliberate action, starting with the positive (horizontal pin of the "T") first and rotating the connector together to engage the negative vertical pin.
  Do not hesitate during the connection process.
  The proper technique minimizes the spark and reduces erosion of the connectors.


Keeping your model aerodynamically "clean" is a very important component in our quest for longer flight time and high speed. A properly set-up BVM Electra Jet or F-86 will cruise around the pattern on as little as 28 amps at 80 - 90 mph.

Properly set-up means that the hatch-to-fuse fits are good and the main landing gear strut doors fit firmly against the bottom wing skin. The nose gear doors must also be firmly closed in flight.

Excessive weight causes the model to fly at an increased angle of attack thereby increasing induced aerodynamic drag.

Good craftsmanship and time spent properly rigging the retracts certainly pays amperage dividends.

We have found that a single turn on the threaded ball link end of the retract push rod can make the difference between gear strut doors that fit properly or not. "G" forces and lifting forces on the wing bottom can cause less-than-perfectly or as is adjusted doors to sneak open in flight.

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