FPV Modded B-03 BWHOOP Less Than 30 Grams - I DID IT! - HOW I Got There!
Those of you who frequent the same circles as I do have probably seen my 2.8 Gram All In One Cam/VTX blog; this build leverages that to bring in the BoldClash B-03 BWHOOP at less than 30 grams, including all-band FPV video AND dual battery connections for both Losi/MOLEX and JST-PH/PowerWhoop equipped batteries.
This may sound heavy for a Whoop, but remember the B-03 BWHOOP is not your usual 0615 Whoop build. They're an interesting variant of the "Chiny Whoop" phenomenon; 0716 motors, rubber frame and built-in JTAG/SWIM port to make flashing to SilverWare plug & play easy. They weigh in at right around 30.5 grams in stock form, and come in Blue/White and Orange/White versions with full canopy for $15-19.
Here she is with my brand new Taranis Plus SE.
This is the AKK S2 mounted on the RakonHeli CF/Delrin mount. I made spacers to go underneath the CF base by cutting short bits off a regular antenna tube; the Delrin part needs to be trimmed with a Dremel and then a strip of foam servo tape across the top & bottom of the camera's PCB to make it fit. You also need to remove the pushbutton as it is right on the edge on the PCB.
Note dipole VTX antenna mounted 90° out of phase with RC receiver antenna, and I replaced the pushbutton with a bit of bronze wire to be able to easily change channels.
Here's my dual power connector mod; the Losi/MOLEX connector is made by soldering the crimps to bits of solid copper wire. I searched my resistors and capacitors until I found one with leads that just barely fit through the holes in the FC. DON'T try to drill out the holes; this will reduce the capacity of the connection because you're drilling out the via that connects the two sides of the PCB.
Here you can see how I reshaped the battery box to accommodate the CrazePony HV stick packs; I cut slots ~11mm apart and ~5mm deep in the front wall of the battery box, then applied a little heat and bent it down into a support tab for the top of the battery. I did this instead of just cutting the material out so that the battery would be resting on a nice flat plane instead of pressing against a sharp edge, just waiting to cut the battery in a crash.
(This pic was taken later, so also shows some holes made for lightening the frame)
This spacer for the CrazePony HV Inductrix "Stick pack" battery is just a 30mm x35mm square of 8mm thick foam; folded into a "U" shape it works perfectly and weighs like 0.08 grams.
I've been flying these batteries from my Axe100 CP ever since I got my BWHOOP; they're pretty light but still good C-rating. Flight time is like about 20 seconds less than the stock battery.
Bare weight is 22.98 grams.
AUW with Axe100 CP battery is 30.60 grams
The CrazePony HV ALMOST gets me under 30 grams AUW; so far the flight time is almost identical to the Axe 100 batteries. I'm still working on an HV hack for my charger; it can't bring these up to full 4.35 terminal voltage. Hopefully when it can I'll get to see what these batteries can really do.
The Axe Batteries don't balance the quad out as well as the HVs; they can balance the camera perfectly. I'm thinking about rotating the Delrin mount 180° to move the COG further back, but I really like the view with the cam pushed forward like this.
So I decided to try reversing the Delrin mount on the plate to see how it affected COG; I found I could get the frame to balance with the Axe100 batteries as I'd hoped, but I also found that since I needed to move the stick pack further inboard, the wires on the PowerWhoop/JST-PH connector were now about 12mm too long.
While I was shortening the wires, I decided to make it so they passed through the frame to act as a strain relief. As this soft rubbery material tends to fight being drilled, I used an X-Acto knife to cut through then trim out the holes.
Here's the finished holes in the frame...
...and the finished shortened PowerWhoop connector. Here you can see that I don't use heat-shrink; to eliminate the weight, I just push the silicone jacket up the wire, solder my connection to the pin, then pull the silicone jacket down over the soldered connection. No extra weight, nice & tidy.
Pleased with the results, I decided to take another pass at cutting my weight, hoping to get below 30 grams AUW as I'd originally planned. I started by aggressively trimming non-critical areas, and beveling edges everywhere else.
This work requires a steady hand, and you HAVE to have a sharp blade... a NEW blade... in your X-Acto knife. Trying to trim this stuff with a dull blade will make it deflect rather than cut, and when you do finally get it to cut it will take chunks out or slice through the plastic or YOU rather than trim the edges.
Remember the old adage; "You only cut yourself with a dull blade."
Here you can see where I removed the middle brace from the battery holder, and removed a couple spots of material from the support tab for the stick packs I made from the front bulkhead of the battery box earlier.
Here I'm shaving flash from around the inside edges of the motor nacellles...
...and here I'm removing similar flash from the bottom edges of the fan ducts. You can also see that I've swapped out stock props for the E010 props; they'e a hair less than 1/10th of a gram lighter for the set, and IMO, they're better balanced and fly smoother than the stock BWHOOP props.
Here's what was removed from the frame; the center brace from the battery box and some of the shavings. This is not everything I've shaved from the frame; this is just what I could easily collect from the workbench and the front of my shirt. Also, I made a similar pile with a less aggressive "shaving session" when I first got my BWHOOP.
I made a new foam with the center cut out; it's not as convenient to install as the original one, but once it's in place it works the same.
And another tiny bit of weight; the paper label on the battery. Interestingly, the battery is imprinted so you can still tell what it is. Another 1/10 of a gram, give or take! w00t!
It ALL adds up; this is, and always has been the name of the game. All offered up in sacrifice before the altar of Performance.
And there we have it; LESS THAN 30 grams AUW with FPV!
This layout actually handles a lot better; the entire mass is closer to the center of the rotor plane in both roll and pitch axes, and I can use my Axe100 batteries again. As I expected, you can see a little of the props & ducts at the bottom of the FOV in the goggles now; it's not nearly as annoying as I anticipated, and it actually helps give some frame of reference when flying.
Just goes to show; if at first you don't succeed, suck something else!