Bob Selman

I now have a DT only version of the timer working.  It is smaller and lighter.  It uses a Mini Vapor servo mechanics for the DT activation.  Weight is about 1.5 grams.

MVC-123F      BSD DT Only Timer v1c

 


 

 

I’ve also finally worked out a software scheme to save a value in the microprocessor I am using.  This will allow me to develop V2 of both the E20 timer and the DT only timer.  V2 will use a programming jumper to select a set of times to use.  Once selected, the programming jumper can be removed and the timer will use the same set of times every time it is powered up until a programming jumper is again plugged in.


 

I have also been working on 3 different E20 model designs.  I have built the prototype Micro Pearl E20 and I am currently building the prototype Appachette E20.  I have parts cut out for the Meteor E20 prototype, but have not started on that model yet.  The Meteor E20 is loosely based on Paul Bradley’s Meteorite E20 model.  A few weeks ago I was able to get down to George’s house and we built up 3 E20 wings from his design Igneous E20.  These wings were modified slightly from his design to conform to my preferred form factor, but the construction technique was George’s development.   These wings will be used on the Apachette E20 and the Meteor E20.  The Micro Pearl E20 uses a different wing construction.


 

I’m hoping the weather will allow me to start flying these FF models and re-learn trimming!  I have not flown FF since my teenage years — about 50 years ago!

I now have the production version of the timer working well.  I have built up 5 units and 5 more are being built by an outside source.

In actual tests, the motor run maximum is 22-23 seconds and the maximum DT time is 221 seconds.  Minimum time for both is 1 second.

MVC-075F        BSD_E20_PB_Illustrations_v2

 

The PCB is just over 3/4 inch square and weight for the system, as shown above, is 2.54 grams.

 

Next I will build the E20 model and do some flight tests on the unit.

I have rekindled my interest in small electric free flights.  In particular, the E20 size models.  I have studied the various FF forums and decided to design my own timer for the class.  I consulted with several FF modelers and found some of the desirous features of a new timer.  Feature #1, motor starts after button is pressed, but the timing function does not start until the button is released – usually with the actual launch.  Feature #2, the DT function cannot happen until after the motor has shut down.

I built a prototype using a homemade PCB.  Most of the time was taken up by trying to get a usable PCB!  Once I had a PCB, I began programming the unit.  It uses a PIC12F1612 and I used MPLAB and the XC-8 C compiler to write the code.  I have the prototype working and here is a video of it functioning.

Now that it is functioning, I have populated the production PCB. Here are the pictures:

MVC-074F MVC-073F

JD Nicoud of Didel fame did the PCB layout for me.  I will spend the next few weeks testing the new production prototype.

Thanks to Paul Bradley, Ralph Bradley, Bill Piatek, Ralph Ray, Nick Leichty, JD Nicoud, Mike Watters, George Harris, Larry Hall and Sergio Zigras.

Bob

George Harris and I have been working on a new RTF model.  It is George’s design and he calls it the RED-E.  George has built several prototypes and his latest version flies very well.  The model spans 14 inches and weighs about 18 grams.  Power is from a 7mm motor direct drive.  For a battery, the 70 mah to 130 mah lipo cell is recommended.  George has tried several graphic schemes on the model and can also offer several colors.   We will also be offering a kit for the RED-E.

The RED-E flies easily in a standard “single basketball court” gym.  It has a good speed range and will slow down nicely since the wing loading is ~0.5 gm/sq.in.

RTF-Red-E 4

 

I have been wanting to start a blog for some time to let everyone know whats happening and what’s coming out next. I finally bit the bullet and had my Webmaster set me up a blog.

Last Spring(early) the emphasis was on finishing up the Peanut series and we have all of those kits available. Ralph Bradley and I had been talking about the 20 inch size models for some time and in late Spring I started working on the Mini series. Specifically the Mini Squire, a 20 inch version of the Midwest Esquire. I finished that up at the end of May and took it to SMALL 2015. I had several pilots fly it and they seemed pleased with it’s flying qualities. It is now available on my site. Next in the Mini series will be the 20 inch Mini Mambo. I have already done a 20 inch Mambo, but I have revamped the plan to use the UM P-51 power plant. This is such a nice size for a 20 inch model. I still need to prototype the Mini Mambo before releasing it on the website.

I have also developed an interest in small electric free flights, specifically the E20 class. I have designed a model and I am currently working on a small electronic timer for it. The timer is 1″x0.7″ and should weigh right around 1.5 grams. It has the motor FET on board and a DT mechanism too. The DT mechanism is a “spin-off” release. There is a small motor that has a worm gear and when the DT is activated, the motor spins running the DT string off of the end of the worm gear. I am currently working on the software and next will be a PCB, so more later.

Bob