Introduction to RC flight through unplanned landings

Vimana89

Legendary member
@veloxsouth : I think you've got the right idea and a clear grasp on what you need to do next to make your build work, which is basically just moving the CG back to the 25-30% range and getting some more reliable servos/making sure cables won't come loose. I don't think anybody was trying to be condescending or pedantic or act like a know it all, though it may have come off that way to you. I have seen this situation happen here before, and what it looks like to me is the same situation: some of us here just have a big passion for the hobby and are overly eager to share our knowledge and perspective and what we have learned, and this might strike a newcomer like they are being lectured at by some hoser trying to sound smart, when it's actually the exact opposite; this person could be simply eager to help you and enthusiastic to share their own learnings and perspectives:).
 

CheckMySix

Well-known member
Saw what Flite Test was doing with foam board and it finally seemed like RC airplanes were approachable.

Bought a flite test explorer kit, a DX6e transmitter and receiver, and a power pack C and overlooked the fact that the kit required a 9x6 prop and modified the power pod to use the 10 inch prop. I was excited to get it in the air that weekend so I didn't make the sensible decision and switch to the 9 and stick with the plans. While trying to keep the thrust vector still going through the cg, I translated it up as high as I could go. View attachment 147401 View attachment 147403

I remember feeling like the plane was a little tail heavy compared to the suggested balance, but let the excitement get to me again. It flew but was way too sensitive in pitch, and after the hand launch it immediately started violently pitching up, stalling and smacking the ground, and the tail boom got a big slash from the prop on impact.

So I swapped to the 9 inch prop that a friend helped provide, threw some wood in the nose, and taped over the slash in the tail boom and got it in the air again! It flew well enough but I suddenly lost power and touched down somewhat gently in tall grass. The prop had come loose.

I tightened the prop, checked my C.R.A.P. again, and launched again. I flew half of a pattern trying to gain altitude at full throttle when my patch job on the tail boom must have come undone. It pitched down hard at full throttle and augered in. The nose was obliterated, the core was torn, the tail boom completely broke in half. It was a sad moment but in the end I knew I could just make another. I already bought spare foam board and all the electronics were in great condition.

Even though I didn't get a good flight in, I've learned a lot about what went wrong, how much of a component my impatient decisions played a part in the loss of my first plane, and I'm already on my way to building my own flying wing with cues from the flite test spear and arrow designs. View attachment 147402
Good for you, man! That's what great about the foam board planes. So long as the electronics survive, you're just out some time, glue and a couple bucks in foam. And... no one dies from impatience....lol.
Flying wings are fast and not very forgiving. Some buddies fly them out at the field and things can go wrong fast. But again, it's just some foam board and some laughs. Sounds like you're hooked. Love it!!!
 

veloxsouth

Member
Good for you, man! That's what great about the foam board planes. So long as the electronics survive, you're just out some time, glue and a couple bucks in foam. And... no one dies from impatience....lol.
Flying wings are fast and not very forgiving. Some buddies fly them out at the field and things can go wrong fast. But again, it's just some foam board and some laughs. Sounds like you're hooked. Love it!!!
I won't miss a good flying day if I just rebuild them fast enough, right? :unsure:
 

veloxsouth

Member
I've been busy but I think I'm ready.

Motivations:
Number 1. Resolve the servo disconnect issue.
I really enjoyed the opterra's AS3X and SAFE modes for learning without it being so stressful and wanted to make that available while I'm experimenting with this plane.
I wanted to design a plane with endurance as its primary goal.
I wanted to quantify how well the plane was designed and guide future changes by logging flight data, analyzing this, and making changes based on the data.

Changes:
Servos are 13g digital, metal-gear servos with a 30% better stall torque, and the cables are taped down to the surfaces near the connection points, and the connectors themselves are hot glued down. Added some HDPE plastic sheets to distribute the force from the control horns. The batteries are now velcro'd in to prevent them from bouncing around in the compartment and pulling on wires like last time.
Increased thickness of the foil from 6% to 12% to put it more in line with the Clark YH airfoil. This should increase the lift (good) and decrease the already negative coefficient of moment (bad).
Added a flight controller and appropriate sensors for the stabilized, and angle-limited flight modes, position and altitude holding modes for loitering, and sd-card blackbox logging.
Added an FPV system with video recording to get data in realtime and monitor power system during endurance tests through the on screen display.
Replaced the foam spar with a wooden spar.

Specs:
eCalc link to show surface area
There are 4 battery configurations I plan to try.
AUW/cubic wing loading calculated here
3S 2200mAh 1004g/ 3.8 slow flyer and thermal gliders
3S2P/ 1174g/ 4.4
3S3P/ 1344g/ 5 Trainers, park flyers, 3D
3S4P/ 1514g/ 5.7 Trainers, park flyers, 3D

The cubic wing loading of an Apprentice S15E is 7 for reference. lower is more floaty, higher is more like a fighter jet.

Pics:
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