Monday, October 21, 2019

PC1100 Battery Post Repair

My favorite F3b winch battery is an Odyssey Extreeme PC1100.   It's only drawback is the weird choice of M6 studs for the battery termination.  I have been using some battery posts I machined for a few years, but I did have one of them where the stud broke.  I might have over tightened it.

The Swiss team mentioned they had broken one and used a Helicoil to repair the battery.  I called up Odyssey and they didn't think there was any way to drill it or enough material there.  But looking at it, there clearly is a bit of lead/copper before you get down into the cell.  I picked up an M6 helicoil kit. 
The only problem is the tap was for a through hole. It isn't a bottoming tap.  So I ground off the end of the tip to make it closer to a bottoming tap.   I tried drilling a piece of lead to see how deep I needed to drill and how well it worked.   It looks like I could get away with 1/2 inch.   The M6 set requires a ,250 hole to tap.  

I mounted the battery in the vice on the milling machine and got out a 1/4 mill  I  figured a flat bottom would be best to get the depth needed. I was able to go down 9/16 without any problem on the negative terminal that I was repairing.

The helicoil installed nicely.  I picked up a M6 bolt on battery terminal and trimmed the bolt to make sure it would be just the right length through the helicoil.   Everything looks fine.    I have a usable battery now.

Odyssey started making SAE Terminal Kits for the 6mm. This is a relatively new addition.  I will be switching to these on the other batteries.

Friday, May 31, 2019

2019 Team USA F3b Fund Raiser

Please visit the Team USA fund raising sight and help the team make the trip to the world championships.

2019 Team USA Logo Complete

The 2019 Team Logo has been completed.  Really nice design.

Wednesday, March 4, 2015

JR tail Servos for Sailplanes

In the past I have used 3421's then 3717HV's for higher voltage installs, especially on all my V-tail models.  I just got two new servos.  The JR MP31Swv and the JR NX3125.   The MP31Swv is the fastest of the bunch.  It is down to .08 seconds on 7.4 volts.  It is a wide voltage servo so you don't have to worry about what battery pack you are using.   It also has just a little more power than the 3717HV. The case size is the same as the 3421's.

The other interesting item is the NX3125.  This is not quite as fast as the MP31Swv but it is an XBus servo.  It's also more flexible in voltage range and it us XBus programmable to tweak the servo if you need to.  What I'm really hoping for is to get the JR398 servo in a NX version and a receiver that just has maybe 4 XBus outputs to use in a sailplane.

Receivers for Sailplanes

I now have some JR 712BX receivers.  These are a really nice package that most sailplane pilots should be happy with.  They have a hard case, and you don't need a separate satellite for telemetry.  The stock two antennas are all that you need.  It's like installing a 731 or 831 without having to put in a remote.

The one I'm really waiting for is the JR 612BX.  This is a 6 channel version which is enough channels for most of my sailplanes.  It also have a lightweight case.  You might notice that there are only 5 servo connections on one end.  The 6th is on the other end along with the XBus connector and telemetry input.  This RX should really work well for DLG's or tight F3b installs.

New Winch

I added a new winch to the connection.  It's an Ober winch with a Bosch motor.  My other winches are all Lucas motors but when they get packed in a Pelican case, it's real easy to exceed the 50 lb limit on luggage.  So I have this winch so I have one that is easier to carry on an airline.

The winch does not have the standard drum sizes.  I never thought those were the best for the motors and the normal lines I use. Normally you get 45mm, 55mm, and 65mm.  The 65mm is useless. I had this winch done with a smaller 40mm base drum size.  Then I have 46mm, 50mm, 54mm, and 58mm sleeves for pretty much an wind condition and line in F3b.

Friday, November 7, 2014

XG14 Spring Change

I usually adjust the spring tension on my transmitters to increase the tension and also install longer sticks.  This way I use more motion in control inputs instead of using really minute movements.  With the XG14 I had the tension close to the maximum with the stock springs but on occasion I would still end up with some aileron input at times like when pushing over and pulling back for a zoom launch which requires a lot of stick movement.

My solution is to get some stiffer springs in there.  I picked up a few sets from Radio South.  Installation requires some good lighting and some tools.  The transmitter back requires removing 3 screws to remove the plastic piece on the carrying handle and then removing the 8 screws holding the back case on the transmitter.  Next I adjusted the tension on the springs as low as possible to make spring removal and installation easier.  I used a really small flat blade screwdriver to grab the accessible end of the spring and pull that end off.  The spring is then pretty easy to pick up out of the back of the stick assembly with a small pair of pliers.    For installation, I took a piece of .020 stainless wire and bent a U shape in the one end.  Hook the spring on the inside end of the spring holder/adjuster and then slide the U shaped wire through the other end of the spring.  The wire can then be used to stretch the spring and pull it to attach the other side.  A really thin wire is required for this so that the spring end can slide into place on the stick assembly and so that you can still slide out the wire once it's hooked.

Fall weather is here and it's going to be cold the next few days. Next week looks like a chance to get out and try out the stiffer sticks.