Archive for the ‘How To’ Category

If you have been following the Bullet Proof RC Plane Build Along series of videos you probably know about the recent crashes I had with the plane due to receiver issues. These crashes were caused by either low voltage lockouts or receiver range issues resulting in two destroyed LiPo battery Packs. After that happened I decided to solve the problem before it destroys any more batteries. Here are a few things I found out:

  • Spektrum makes a plug in capacitor to eliminate low voltage lockouts
  • Spectrum Parkflyer receivers only have a 1000ft range
  • Park flyer receivers are not recommended for fast planes or high flyers
  • LiPo Batteries can be disposed of easily and are environmentally safe
  • LiPo batteries must be completely discharged before disposing
  • Bad or damaged LiPo Batteries can be safely discharged in a salt water solution.

Please watch the video below for more information:

 

Thanks and I hope This can be useful for anyone having these issues or better yet will help to keep you from encountering them. If you do end up with any damaged Lipo Batteries you will at least know how to dispose of them properly. Thanks for visiting rcFoamFighters Blog and for all your support. Here are some links to the information I found.

Downloadable PDF file on ThunderPowerRC web site on proper disposal of LiPo Batteries:

 http://thunderpowerrc.com/html/downloads.html

Spektrum plug in capacitor to eliminate low voltage lockouts:


Forum on Spektrum Parkflyer Receiver Range :
http://www.rcuniverse.com/forum/m_6555830/tm.htm
 

We have been getting a lot of questions in regards to what we have been using to cover our RC Planes.

“How do get your rc planes so smooth?” “What do you use to cover your RC Planes?” “Where can I get Colored Sealing Tape??

So We wanted to just do a little write up to answer these basic questions.  Typically we have been using simple, low cost, colored carton sealing tape or packing tape. This low cost covering adds a nice shinny finish to your scratch built remote control foam plane. Below are a few examples.

rcFoamFighters Bullet Plane, FF-22 and FF-23

rcFoamFighters Bullet Plane, FF-22 and FF-23

The sealing tape works best with Foamboard RC plane designs since the surface of Foamboard is more easily gripped by the tape’s adhesive.  The sealing tape will work good with EPP, Depron or other foams too, but may be a little trickier to get it to attach to the surface well. Usually when we use the sealing tape with EPP or other Foam materials,  we first put strapping tape  around the edges of the wing and parts of the fuselage since it is more tacky and better at attaching to the foam. Then we run the layer of sealing tape from edge to edge, attaching to the strapping tape at the edges and uncovered foam in the middle.  Also we have noticed the sealing tape bonds much better when it is an EPP RC plane covered first with the Henry Brand Fiberglass Weave and adhesive, like on the EPP Park Jet and Bulletproof RC Plane.

One tip about using sealing tape that may help you in making your remote control plane look better, is to use a heat gun to shrink the tape. Typically Frank and I use a heat gun after the RC plane is fully taped up. You can use the Heat Gun to slowly heat up the tape till it starts to shrink just a little.  This will get rid of the wrinkles and make for a nice tight covering. Usually the sealing tape will first suck up close to the foam as its heated and actually reveal more wrinkles. But then as it slowly shrinks more, all the wrinkles tighten up and go away. Just be very careful not to hold the heat gun too close and over heat the tape. This will cause too much shrinkage and can even burn right through the tape. Its best to keep the heat gun moving back and forth and slowly heat the tape up. Hopefully soon we can do a  video demo of taping a plane with this method.

Just remember sealing tape is just one option you can use to cover your RC plane and make it look nice. It will also make your RC Plane stronger. You can always use stuff like Monokote or Trimkote or similar materials. These just tend to be a little more costly. Anyway hope this helps. Just know we are constantly looking for new ideas and ways to make the hobby more affordable. We will try and pass along any tips we learn about to you our fellow RC Pilots/Builders. Please feel free to let us know of any tips you may have too make RC planes better and/or more affordable. The more we all learn together, the more fun we will have at this hobby of scratch building cool remote control planes.

So far we’ve had a hard time in finding any stores locally that sell colored sealing tape. We usually just buy our tape supplies from the internet. So last I just wanted to provide you all with a link to TapeBrothers.com, the place we get our tape from and seem to be the best priced.  rcFoamFighters is not an Affiliate of Tape Brothers, but we do recommend them based on our past purchases. They are fairly quick to ship and have good prices.

(click on picture to go to Tape Brothers Site) 

Link to TapeBrothers.com

Link to TapeBrothers.com

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Step 1: Selecting the Motor

First you need to know the estimated overall flying weight of the plane you are planning to build.  If you are building from already made plans they will usually list the estimated All Up Weight or AUW.  If you are building totally from scratch, try and find an already made plan to a plane that is fairly similar in shape, size, wingspan and building material to the one you want to build. You can use the weight of the similar plane to get a real rough estimate to start with. After you have built a few planes you pretty much develop a good sense of  weight dynamics and will be able to estimate right out of your head.

So now you have your estimated weight of the plane. For this exercise lets say the estimated plane weight will be about 18 to 20 ounces. We usually like to make fairly high performance planes, so we always choose motors that are overrated for the target weight of the plane we are going to build. We usually look for a motor that will put out a thrust level of around 1 to 1.5  times the All Up Weight of the plane. For unlimited vertical flight we prefer it to be 1.5 or better.  So in this instance we would need to pick a motor with about 20 to 30 ounces of thrust to get to that 1 to 1.5 power to weight ratio we mentioned above. For this example we will choose the Suppo BL-2212/6  2200kv Brushless Motor Rated at about 27 ounces of thrust with a 6×4 prop and 3S Lipo.

Now that you have selected the proper motor for the particular project, it is important to know the Max Amp Draw the motor will demand. You can usually find this information on the manufacturer’s web site or the site you got the motor from.

   Example:

   Suppo BL-2212/6  2200kv Brushless Motor Rated at:

   Max Efficiency @ 22amps

   Max Amp Draw (28amps) for 60sec

Step 2: Selecting the ESC

Now that you know what amount of Amp Draw your motor will demand, you need to choose a properly sized ESC. You will need to select a Brushless ESC that has a slightly higher constant max amp draw rating than the motor’s max amp draw. Most ESCs have an over amp shut down built into them to protect the ESC and motor from drawing to many amps. It is very important NOT to choose an ESC with too high an amp rating. An oversized ESC can allow too many amps to get through and as a result you could burn up your motor. (Unfortunately we learned this lesson the old fashion way, as I’m sure some of you have….LOL)

So for this example we would choose the following ESC to match the motor:

   Suppo SP-30A ESC Rated at:

   Max constant Amp draw (30amps)

(Now that you have the Motor and ESC selected Go to the post “How to Find Your Lipo-Battery’s Maximum Constant Amp Draw” for help on picking the proper Lipo-Battery to power this system)

Link to a PDF copy of this Document: http://rcfoamfighters.com/FileDownloads/How_To_Select_Brushless_Power_System.pdf

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We have been getting several questions about power systems and batteries. So we thought we would first do a “How to” guide on finding what your Lipo-Battery’s Maximum Constant Amp Draw is.  Knowing how to find this can help you better design your RC Airplane power system correctly and help keep from overheating, puffing, and/or destroying your Lipo-Battery.

Here is a simple formula that we have found to be commonly used in the RC Community to find the Maximun Constant Amps a Lipo-Battery is capable of sustaining.

Formula:   (C-Rating) X  (AH) = Maximum Constant Amp Draw

Now to use this formula you first need to convert your battery size from the common MilliAmpHours to AmpHours.  A MilliAmp is One-Thousandth of an Amp.  So here are some Examples of converting MilliAmpHours to AmpHours:

800mAH = .800AH

1350mAH = 1.350AH

2200mAH = 2.200AH

The converted number will be the “(AH)” in the formula. Now that you have your “(AH)” number, plug it in to the formula with the “C” rating number of your Battery and Calculate.

Here are some Examples:

(800mAH 10C Lipo Battery):   .800AH  X  10C = 8Amps Max Constant

(800mAH 20C Lipo Battery):   .800AH  X  20C = 16Amps Max Constant

(1350mAH 15C Lipo Battery):  1.350AH  X  15C = 20.25Amps Max Constant

(1350mAH 30C Lipo Battery):   1.350AH  X  30C = 40.50Amps Max Constant

(2200mAH 20C Lipo Battery):   2.200AH  X  20C = 44.00Amps Max Constant

(2200mAH 30C Lipo Battery):   2.200AH  X  30C = 66.00Amps Max Constant

After you Know what your Battery can Handle:

Now that you know what your battery can handle, you can now choose an appropriate power system that will meet the battery’s output range. Good common practice and recommendation is to use a battery that is rated somewhere between 1.5 to 2 times the actual max amp demand of the components installed.  (Motor / Prop / ESC / Servos / Receiver / etc.)   So in example, if your motor/prop/esc demand 20Amps max, you should use a battery with a Max Constant Amp rating of 30 to 40 Amps or better.

The best way to see the actual real time Amp draw of your power system is to use an Amp/Watt meter and test with the actual setup to be used. As a starting point you can also refer to the manufacturer’s spec sheet for all component ratings.

Here is a link to a Free Excel Calc Tool we have made to make it easier to estimate  your battery’s max constant amps. It is based on the above formula. Please use at your own discretion.

http://rcfoamfighters.com/FileDownloads/Lipo%20Battery%20Amp%20Calc.zip

Pic of Tool:

max-battey-amp-calc 

Here is a link to a PDF copy of this document:

http://rcfoamfighters.com/FileDownloads/FindLipoBatteryMaxConstantAmpDraw.pdf

Hope this helps.

Frank & Paul of rcFoamFighters

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