RCP Mig29 with custom bamboo reinforcement and a KF 4airfoil
GraysonHobby MicroJet v3 throwin a 6x4 prop
30 amp RCTimer ESC
1500 3cell 30c
2x 9g digital metal gear servos (EXI)
In order to tell you how I modded and built my RCPowers Mig29 I have to teach you how to lay Bamboo into foamboard.
I use Cheap dollar tree foamboard, it is called Adams Readiboard. I have also seen it at Fry’s electronics in multiple colors for a higher price. I pay one Dollar per sheet and the sheets are 20x30 inches. This foam has a paper glued on each side, it can be easily removed (with water) but I leave it on the foam for added strength. This airplane is not water proof and the paper will peel off it you get it wet.
Another unique aspect of my build is that I used bamboo onlyand no carbon, I have given up on carbon and only use the recycled pieces I bought as a beginner. Bamboo is a cheap alternative to carbon; it is cheaper, and lighter than carbon. BUT, it is shorter, so you must get creative with your build process or people’s plans that usually require larger or longer pieces of carbon rod. I find bamboo “skewers”, as they are sometimes called, in the grocery store in the cooking section or at the local dollar store in the summer when all the BBQ stuff is out. They can sometimes be found in the hardware store too. Make sure to cut off the sharp point on one end, it could be very dangerous if you crashed into anyone. I use hot glue almost exclusively except for the motor mount which is epoxied on with some extra blocks of foam to reinforce it. The hinged are thesame strapping tape that Dave uses.
If you are using Depron use the traditional method of cutting grooves for the carbon rod, you can skip this section, but you may becurious to learn new methods. I should make a video of this and I may soon, but I will try and explain my process, it’s simple and easy.
I hold the bamboo skewer to the foamboard where I want it and I trace it with a pencil, its ok if it’s sloppy, just try to get close and match the shape of the skewer. You're drawn outline on the paper will be wider than the skewer, this is ok and actually, it’s what we want. Now find a supersharp razor, brand new, always use a sharp blade and if it begins to cut poorly, replace it right away, I usually use three blades while building the Mig29. I have given up on expensive blades, I now buy packs of single sided razor blades and just hold them with my fingers, nothing fancy, in fact I do my best workthis way.
Hold the blade at an angle and cut along the lines trying not to go all the way through. I usually cut a nice V shape so both cuts intersect somewhere deep below the paper. Now take a piece of bamboo skewer (the rougher the end, the better, cut the end at an angle if you must) and use it to pick the foam out of the groove you just cut, you obviously make two little cuts on either end of the groove to terminate it. Once you have pulled out the triangular cut or dug it out piece by piece because you didn’t cut it very well, Take the piece of bamboo, hold it at a right angle to the foamboard and slide it back and forth in the groove, don’t be afraid to be rough, but don’t puncture the paper on the other side. This will ensure the groove is the same diameter as the bamboo for its entire length. Then test fit the piece of bamboo in the groove, if it is not flush with or below the surface, then repeat the last step by sliding the bamboo at a right angle up and down the groove, the foam should just fall out.
Gluing the Bamboo into the foam is pretty easy too. I just lay a fat bead of hot glue right down the entire length of the groove, filling it about half way up. Then I lay the bamboo in the grove and push it down, the hot glue will squeeze out along the edges where it needs to. Then just scrape it with a flat stick, like a small piece of ply or a Popsicle stick cut at anangle (to make it wider). You can do it with you finger but it hurts.
On my Mig29 I placed the bamboo along the nose, in the two long pieces on the bottom, in the wings of course, and in the elevons and horizontal stabilizer. I used a KF 4 airfoil and simply cut four airfoils from the plan and slapped one on each side of the wing. Along with the bamboo this makes for a very strong wing, I also cut away some of the flat bottom piece to allow more airflow and this did away with the need for a hatch or door which reduces weight. You can see all my bamboo placements (except the bottom pieces) in this picture.
I tried to maximize the throws as much as I could. The control rods are close to the control surfaces and on the outer hole of the servo horn. This gives maximum leverage and reaction speed but with less torque (and strains the servo) so use high quality digital metal gear servos.
It’s important to have good orientation of this bird at all times; she can get away from you real quick. I realized before I flew it I needed to have the top and bottom highly contrasting each other. I just used large felt pens to color in stripes, red on top, blue on the bottom; I like to keep it simple. Here she is all ready for the maiden.
I used a DX6i and I will explain my programming as well. Iset dual rate (D/R) combination (Combi D/R) to the elevator switch or which ever D/R switch you prefer, this combines all the dual rate switches into one, I prefer the elevator D/R switch because it's the easiest to get to while I am flying a elevon only airplane. This is an important step because we want to free up the aileron DR switch for another function, I will explain later.
The next step it to set the Wing Type to delta/elevon, thisstep is obvious and you have to do this anyway if you are using the DX6I. The next part is the key to making the Mig29 do summersaults so follow closely.
Then go to Mix 1 and set it to mix Elevator to Elevator at125% up and down, set it to be activated with the Aileron D/R switch. I know this sounds weird; to mix one channel with itself, but the DX6i does not useall the available travel when in Delta wing mode. This mix squeezes that extra travel out of the computer. I learned this from a youtube video as analternative to using the Delta mix, but I discovered that both methods can be used together for added mayhem.
Repeat the same thing for the ailerons, go to Mix 2 and mixAileron with Aileron at 125%, left and right, set it to also activate with the aileron D/R switch, the Aileron D/R switch.
Now, when you are flying you have the normal dual rates onthe elevator D/R switch, (I set mine at: Low - 50% EXP 15, High - 100% EXP 35), this changes both the aileron and elevator channels at once. Your setting may need to be different depending how you setup you mechanical throws or how you fly. The extreme throw comes in when you hit the Aileron D/R switch, which mixes both channels into themselves and you get way way more throw than normal, this switch can be set either way at any time and is independent of your normal D/R settings. You do lose some expo while the two mixes are both active, so keep this in mind, the expo is not applied to the added throw the two custom mixes provide. This basically gives you two D/R switches, one for low and high and another for high and extreme, you can combine any combination during flight to get the results you wish.
In the video when I do the somersaults, I flip both switches down at once and pull up like I am doing a flip. To recover I quickly flip themboth back and straighten the stick, timing is everything to make it look convincing. I can come out of the flips going forward or back the way I came with good control after just a few flight of practice.
This isn't all pilot skill, it's know how as well....and knowing if half the battle...
Here she is after her 1st day out; it was a glorious day for everyone at the field. She ran right into the back of a flat street sign hungover the road about 300 meters away, I couldn’t repeat it if I wanted to.
Here is, is her current form with a new nose hot glued on,she still flies great!