Buzzbipe RC 010

4.09oz is ok normally but the plane design requires the weight to be minimal.
Bit of right thrust and a bit of down thrust would help with those thick flat bottom airfoils.
Torque is controlled somewhat even though the spans are short.

The entire horizontal stab is small compared to the gross square inches of the wing panels.
It also has a short tail moment which will require a hair bit of a forward CG to tame the little rascal.

I have a TD .010 project that did well as a mono wing 4.7oz RTF.
16.5"x 4" span airfoil sheet wing 66 sq. in. Great sport flying.

Thanks Brad sounds logical. Will offset the engine and see..

On launch you need to let it fly down to pick up speed and let it decide to climb itself once its going its fine, if you touch the up elevator ( i actually now i tend put a tiny tiny bit of down elevator just after launch to pick up speed! )

Are you using more rubber bands than in the photos? , I use minimum 3 thin bands each side

Thanks I will try this launch technique. Only 1 rubber band each side that holds well and is not aged yet.

What control throws are you using, I have looked on original plan ( missed off new plan ) and its 3mm each way rudder and elevator.

It is more in the range of 5mm but by the time I reached the controls on my radio the plane was already  in a spiral so no real chance so far to set throws and trim it. I have offset the engine now and given a bit downwards  to the elevator and will check it soon in the field...too bad this is such a cute plane and would probably fly like a ball were this not for its strange behaviour..will revert back soon with results.

P.s. I suggest you also indicate on new plans sold with the kit what engine offset and control throw values you have found working best.

Balogh,

I am not an experienced RC guy, but if it were me I would be going back to the basics and making sure everything is 100% straight, it doesn’t take much to twist one of those little wings when shrinking the covering, it also doesn’t require much of a twist in the wing to cause problems either.

Just my thoughts, I do hope you get it sorted.

Ron

Thanks Ron I agree the smaller the plane the more precision should go into building it. This has been the first plane after many that I built with its original hard balsa spars and leading edge instead of carbon hollow section replacements that guarantee torsion free wings and have proven very efficient. So some hard to see wing torsion cannot be ruled out.

Winds were too high today to try to trim the Buzzbipe but I will keep truing.

The last 4 TD .010 projects all required very small throws to motivate directional change.
Before I reached the correct throws 2 would spiral in the 16.5x4 wing was the most tame
and flew very well on the maiden flight.

The last project 2.2oz RTF only has 2.5 mm throw up and 2mm down in the elevator, any more
and it will cause too much abrupt unwanted change. The ailerons took 2mm to fly on rails, before
that total heart thumping wild cat! Full up elevator would cause it to snap at full throttle originally
set at around 4mm. 15.5 in. span 28 Sq. in. wing. 3" x 1.25" wing panels a real sweetie once
dialed in. took 3 efforts  / crashes to get the trims low enough to tame it in flight.  

16.5"x 4" span airfoil sheet wing 66 sq. in. could handle the most throw around 5mm on the elevator
and 4mm on the ailerons. 4.7 oz RTF

18" span 45 sq. in wing. 3.38oz RTF  took small throws as the cord was around 3.25" x 1.75" at the tips.
3mm on the ailerons and 2.5mm ailerons. This one is a good middle of the road flyer for TD .010 engines.
Flies like a micro sized pattern plane.

21" span racer was the most fuss free out of the bunch but also the slowest. Throws for the larger span
was more typical for it's size with little fuss on the maiden flight.

Hi Andras, You say that you launch the model and start to make a horizontal spiral, in what direction does it rotate ?, to the right or to the left?
You have a model with a very short tail moment, therefore you should control your CG, that is, this tubal or nose nightmare.
Check the angles of incidents of the wings and once I control that, take into account if there is any difference between the marginal edges of the wings.
The motor must respect the inclination indicated by the plane, usually 2 degrees below and two to the right.

Thanks Mauricio it starts to spiral to the left so offsetting the engine to the right may help. My suspicion is about the slightly different dihedrals in the 2 wings too. It does not affect the general simmetry of the plane but the flight stability?

Typically the lower wing will have more dihedral or the only one with.
Dihedral will help some with prop torque and a must in the turns with only rudder control.

That is ok, the main issue is needing right thrust / correct CG
You can shim with 1 washer may need two. From there you can
make a hardwood wedge to the thickness found using test washers.
The final wedge design can have a tad down thrust.

Just in case , have you checked the balance left to right in case one wing is heavier? , just a thought

I am beginning to wonder if its too light at the bottom with the light servos.

the original models and the one I fly now have heavier radio, so the bottom of the model is much heavier, on my last one it has much bigger servos ,

Could be like the old freeflight models that people fitted heavy wheels to get stability

Wondering if the light weight at the bottom is helping it flip into a spin? but you have bigger batteries than me so shouldn't be a problem

Maybe its better with heavier servos, I have never needed to change anything like thrust line on them.

I am going to put the radio back in my old one next week and put batteries on the top of the wing to see what happens the next weekend ( cant do it this week supposed to be at a show in the uk and traveling there isn't going well! at all, big lorry is not behaving...third axle thingamy at the back has gone very wrong) !

Weight is rarely better unless you have a slope soaring type plane or glider on a windy day.

What is the gross square inches of the wings combined?

MiniatureAircraftFactory wrote:Just in case , have you checked the balance left to right in case one wing is heavier? , just a thought

I am beginning to wonder if its too light at the bottom with the light servos.

the original models and the one I fly now have heavier radio, so the bottom of the model is much heavier,  on my last one it has much bigger servos ,

Could be like the old freeflight models that people fitted heavy wheels to get stability

Wondering if the light weight at the bottom is helping it flip into a spin? but you have bigger batteries than me so shouldn't be a problem

Maybe its better with heavier servos, I have never needed to change anything like thrust line on them.

I am going to put the radio back in my old one next week and put batteries on the top of the wing to see what happens the next weekend ( cant do it this week supposed to be at a show in the uk and traveling there isn't going well! at all, big lorry is not behaving...third axle thingamy at the back has gone very wrong) !

Thanks, I indeed believe the plane may not have the CG low enough with the light weight of equipment inside...yes, it tends to flip over and go into the spiral as described. maybe I should add the landing gear to bring the CG lower...(but in the deep grass in the field where I fly this will result in a dented gear when it hits the weed on landing..this is the reason I practically fly only planes without landing gear.)

1/2A Nut wrote:Weight is rarely better unless you have a slope soaring type plane or glider on a windy day.

What is the gross square inches of the wings combined?

Brad I am not at home now to measure the dimensions, but assume the 20cm wide wings may have a 8cm core length so the total wing surface is altogether 320 sq.cm or 49.6 sq.inch

The tail is about 40 sq.cm or 6.2 sq.inches

At nearly 50 sq. in. certainly within range for a 4.09 oz plane.
Will be pretty fast once you get it up and running.

The more we have talked about it -and I thank you all for your valuable suggestions - the more inclined I am to think we have a balancing rather than aerodynamic issue here. The CG sits above the line connecting the spinner tip with the rear bottom edge of the fuselage. When supported on those 2 points the plane flips over.

With this experimental and weird outboard battery position I could lower the CG below that line and I will maiden it tomorrow.

Distance from the leading edge of the upper wing to the rear edge of the lower wing = X
X / 3 =? It is there where you must take the CG and cut it or drop it from the nose or motor 15 degrees, do you understand?
Keep in mind that you also place grades to the engine and it will make your model a show! Believe me! :-)
Engine: 2 degrees down and 2 degrees right

Incidence:

Thanks Mauricio I understand. The engine is already offset to the right. And yes the CG is nesr the main spar of the top wing..I seem yo have problems with the vertical pisition of the CG. This is why I mounted - only for experience - the battery below the fuselage...lets see hiw it works. So far the plane has always flipped over because of the CG being too high up, and entered a spiral.

Sorry, I'm editing the text since the translator doesn't allow me to tell you correctly what I want to say!!!!!

According to the behavior that describes what the model does, it coincides with the theory, its model is heavy tail, therefore, the loss (entry in alar loss) will occur with the sum of the engine did not have the correct inclination, turn left.