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BlunderBee 3-4 channel trainer

Ryan O.

Well-known member
#1
Edit: A lot has changed in the design process, I've actually based the aircraft on an entirely different balsa plane
My local flying field has an anual "Builders Workshop" that is open for kids at a local Rec and maybe the local hobby shop too this year. Last year they built the Simple Scout, but wanted something their own and more unique. Since many members at the field have a soft spot for vintage and antique RC planes (including me, after all in three days this is my second article about such an aircraft), it would be cool if new members also had connections to the Ugly Stick, Swizzle Stick, Lanzo Bomber, Smoothie, Kadet, Laker, Slowpoke, Kobra, ETC. At a previous event the club president brought his DIY Ugly Stick. That will probably be at at least one of the workshops. I thought of making a foam board scaled down 4 channel Lanzo Bomber. The Lanzo Bomber can use a pretty small motor for its size so scaled down be the right amount it should work perfect with a motor that is smaller, but can be bought in bulk for dirt cheap. The goal is to have the Radio system (either an FRSKY system for slightly more or an old 72mhz system) along with all the electronics add up to 80-85 dollars, and it should be possible. The problem with the Lanzo Bomber is that our field requires a barrel roll to pass the pilot test, and it is better if a student doesn't need to find a new plane to learn ailerons on. Because of this, I need to put ailerons on it (P.S. I really dislike only steering with rudder as well, just personally). They could either go in the center part of the wing, but they then need to overcome the torque of the remaining half of the wing, or on the part that is flared up due to polyhedral. Will I need to decrease the polyhedral to attach the ailerons effectively, or should it be find. Again, ailerons are a must, but it would be cool if I could put one servo in the middle of the wing (like the Bloody Baron). I might attach a paint stick to the wing and stick into the brace that holds the wing along with #64 rubber bands to keep the wing secure. A bonus of the design is that because of the recognizable engine sticking out of the front not being enclosed by anything, I can make a dummy engine for fun, and it should be easily swappable. The last challenge is that it could be tail heavy. I could cut lightening holes or peel back the paper on the inside of the foam board near the back to save weight, after all the plane needs to be relatively lightweight and nose weight is something I want to avoid. The landing gear should be no problem though, they are nice and simple. I might give it a molded wing because it is theoretically lighter because of the removed paper. I will make two prototype wings and compare them. And the best for last, the good old blue 9 gram servos! There have been many foamboard ones of these, and I wanted to try my hand at designing one myself.
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Piotrsko

Well-known member
#3
Yes you need to make the wing flatter. If it doesn't fly all that fast you could make torque style aileron actuators,all the way out to the tips, like what ACE used on their flat wings, basically a Z bend with the middle in a brass/plastic tube attached to the TE. And with the polyhederal, they need to be up going more than down.
 

Ryan O.

Well-known member
#4
Yes you need to make the wing flatter. If it doesn't fly all that fast you could make torque style aileron actuators,all the way out to the tips, like what ACE used on their flat wings, basically a Z bend with the middle in a brass/plastic tube attached to the TE. And with the polyhederal, they need to be up going more than down.
thanks, I probably remove the slight dihedral in the middle, and maybe even add some anhedral. I decided to use 2 aileron servos so that I could move the servo arm back a click or two because the radios probably won't be computerized and therefore cant mix in rudder. They also can't mix differential so because of that I will use 2 servos with a mechanical advantage allowing the aileron going up to travel further without mixing. The Anhedral might make the wing look like a bird which is cool too. It may end up with an optionfora wing with much less polyhedral, and one wing with less, but not much less polyhedral and an anhedral center.
 

Piotrsko

Well-known member
#5
Well as long as the center of mass is below the wing by a bit (it is), does not matter that much if you have lots of dihederal or just a little OR even some anhederal [ but the tips still need to be slightly above the wing]. The original used all that so it would be very stable which you won't need flying RC. Remember: you need dihederal for rudder effectiveness, but it lowers aileron effectiveness.

I noticed that it also has a lifting stab, so you may want to make the wing further back or make the nose an inch longer.
 
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Ryan O.

Well-known member
#6
Well as long as the center of mass is below the wing by a bit (it is), does not matter that much if you have lots of dihederal or just a little OR even some anhederal [ but the tips still need to be slightly above the wing]. The original used all that so it would be very stable which you won't need flying RC. Remember: you need dihederal for rudder effectiveness, but it lowers aileron effectiveness.

I noticed that it also has a lifting stab, so you may want to make the wing further back or make the nose an inch longer.
I was going to give the stabilizer a KF step which should generate lift to raise the nose again. It should work just fine.
 

Piotrsko

Well-known member
#7
Go with just a flat plate stab and move the CG just in front of the high point. Easier to build, more normal flight tendencies. The flying stab in the plans pushes nose down and allows a REALLY aft Cg. Good for thermal, lousy for newbies.
 

Ryan O.

Well-known member
#8
The motor is going to be the old power pack b motor with a 10x4.5 prop which is exactly what I was planning to base the plane around. I can nake it a meter or a meter and 200 centimeters. It may have to use a bank and yank system instead of 4channel. If so then I will leave lines for a rudder to be installed.
 

Ryan O.

Well-known member
#9
Major update. Kids who are new to the hobby will be building this so I decided to find a plane that works better with ailerons and is easier to build. The QueenBee plane is very similar and I first saw it on Robert Petrïncic's youtube channel. Because this has simple dihedral the ailerons will be more effective and the wing will be lighter. It will be the same size, but the wing mounting extension might be attached to the wing with glue and ti the fuselage with rubber bands.
 

Ryan O.

Well-known member
#10
I have the wing finished and it is probably the easiest one to build I have yet to design. The Baby/Queen Bee had an extension to mount the wing on like the lanzo bomber, but it is a rectangle and is shorter. I might make on piece of foam coming down from the wing and the other come up from the fuselage that can be joined with skewers, the foam where the skewers go through will be reinforced with a piece of drill through paint stick which will also keep the mounts from creasing or folding. In the event of a crash the weak spot is purposely designed to be the dirt cheap skewers. In Robert Petrincic's video the Queen Bee was plain white with some translucent orangish yellow covering in some areas in the shape of a honeycomb. That will be one of the templates for painting along with a white wing with sharpie lines to look like a bee wing and a black and white striped fuselage to look like a bee. There is also the U.S. Army Air Corps trainer aircraft scheme like on the PT-19 and the PT-17. I may come up with more ideas, but the current ones are all easy to do with some steel wool, a sharpie, painters tape, and a spray paint can. They won't paint it in the Builders Workshop, I think, but they might later on and some field members and I could probably show them how to do it. There are also man good videos for how to paint both types of foam board.
 

Ryan O.

Well-known member
#11
I was thinking of a name because it is larger than the BabyBee and smaller than the QueenBee, and I came up with nothing good or original. Then I was watching a history video on the 6day war and the narrarator said the word blunder. I realized that it was perfect for a trainer because in the begining everyone makes mistakes. The BlunderBee is now my official name for the project. Tonight I will show my partially comppeted prototype to the other members designing planes so anything that needs to be changed can be changed.
 

Ryan O.

Well-known member
#14
I have some good news and great news. The good news is that the BlunderBee has enough wiggle room in the cost to include a rudder servo so that it can taxi along the ground, and have better control in the air. The great news is that it actually flew!!! The maiden flight was uneventful, and after I trimmed it out other field members were flying it too.
 

Ryan O.

Well-known member
#15
So, to keep it slightly stronger and crash resistant the wing mount will be made from elmers foam board. The strengthening wood pieces will be ply that we will precut. Luckily the club president has Adobe Ilustrator, so he will make the plans digital so anyone can print them out. I am still looking for a free 2d CAD program that can make curves and PDF images. Instead of a 10x4.5 propeller I will use a 9x4.5 prop because otherwise it would be shredding the grass every time it takes off. In the future I will probably make a buipd video for this plane so that any students can rebuild parts with instruction on how to do so. I might also make a build video for the other aircraft, overboard (a plane like the CTH Albatross, but smaller with a quad motor and a smaller Ugly Stick which will use the same power system as mine, but with a 10x4.5 prop.
 

Ryan O.

Well-known member
#16
I finished the wing for the plane that will be shown at the builders workshop. Its supposed to look like a bee wing and the fuselage will look like a bee with two big googly eyes to top it off. I am redesigning the landinf gear to make ir simpler along with the wing mount.
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Ryan O.

Well-known member
#17
I decided to install the landing gear to the firewall. It will be 3d printed with two holes so that the gear can be inserted and swapped out.
 

Ryan O.

Well-known member
#18
I installed magnets into the wing mout as well as building the fuselage. all that is needed now is to make the new firewall for the landing gear. I also need to paint it.
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Ryan O.

Well-known member
#19
I designed a bare bones firewall with the holes for the landing gear wire for printing in PETG. It takes 1hr to print in .2mm layers, but I recomend .1mm layers and extrem tape strengthening.
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Ryan O.

Well-known member
#20
It flew fine until I got to the same distance from my radio. Then Ailerons and elevator would cut out, causing it to crash. The magnets detatched and the wing and plane were fine. I'll need to replace the reciever before the next flight.