Hovered 10 inches; battery was not fully charged; bit of a shutter, tweaking the lower hub. Video tuesday/wednesday. In the field a couple of days; live fire tomorrow. Out of town a couple of days later this week. Worst case, thorough update this week-end. Promise.
Από κάθε γενιά μεταξύ κάθε έθνος ανθρώπων, να θυμάστε νεκρών στρατιωτών μας.”
Coaxial proto flew, cg is off. Drifts aft and left. Making adjustments this weekend. Cutting weight.
Finally, I have control of this rotor platform. It's the coaxial version of my patent, but still a "planform" (configuration) morphing airframe rotor disc control system; two airframe inter-connected with the weight equally distributed between both airframes. No swashplate. I still need to tweak the yaw control a bit. I think one of the rotor hubs is turning slower than the other. I did add a small washer with teflon grease, but it may be causing slight friction, slowing one of the hubs. More tweaking later.
First outdoor flight. I'm still not satisfied. I need a stable hover, but the transmitter/receiver are real cheap. It started cherping. Not consistent enough. Going to gut it and upgrade to better brushless motors.
Crash damage has already been repaired, but the cherping noise showed up. Not a big deal. May be inconsistent electrical current flow from the battery.
Cherping noise developed. Again, my fault....cheap hard ware. I'm going to attempt to change the battery and if that does not work, going to gut it. I need real stable hover control for the ability to negotiate obstacles.
A few pics. One showing the swash plate that I removed, so at least I attained the goal of controlled flight w/o a swash plate. Another pic of the crash damage and the last of the adhesives that I use in conjuction with CF gusset plates. Gorilla glue first, let it cure, then apply the flexible adhesive.
I'm tweaking the single mast again, but I had intended to throw a "rat rod" helicotper together for the son of one of my Army buddys. I started to use a swash plate and got aggrevated. Now, it will be the 2nd prototype of the single mast. He'll have something to drive his parents crazy and I'll have a proof of concept video for the single mast.
Yeah. Not dealing with torque is one less thing to worry about. Rotor/engine rpms are watched, plus everything else around you.....equals a busy operator.
I have plans to use the diff gears as well for the sketches on the manned platform, but I'm using two masts, one internal for the upper hub rather than having the diff gears between the two hubs, stacked like the schoffmann. A little bit more weight, but my coaxial is a bit larger than the schoffman, will have collective pitch, 50 HP power plant and the rotor-props are bit longer than the Ivo props used in Schoffmann. Rotor chord about 5 to 6 inches and the hubs will have flapping & lead lag hinges. The diff gear assembly will be built into the pendulum airframe at the top of the platform with a reduction pully (gates poly) to bring the rotor rpms down to safe speed. This will alllow me the access the diff gears for small adjustments, if needed, as well as provided an "oil bath" for the gears. This is why it's also taking a bit longer to get all of the sketches done. It's not just a few pages.
Next month I should have the parts ordered to start the larger coax proto to finally get around to sling load trials, but money has been tight and bills come first. I'm so far behind, but I never stopped. I just had to switch to paper to work out some airframe routing issues so that the gimbal joined airframes move within one another. It's one thing when all you need to do is slap a battery, servos and motors, then tweak the CG to get it right then fly it around a tennis court. Everything changes with the addition of an actual pilot. I have to draw back up designs at certain points to have an alternate for CG/CM adjustments.
Yes it is possible, but 2 things to consider: 1st- the addition of a collective pitch control linkage...how much weight will this as well as the addition of a sprag clutch add to your Schoffmann Helo? It's already a very light weight design. the ones that I have seen flying never go higher than a few meters. A point of interest for buidling any VTOL concept is that the power plant will have a vital role in lift to weight ratios. Example: 1 horse power is required for every 10 pounds of weight. Additionally, will your shorter "rotor props" have enough span to perform an auto-rotation? I watched a vid clip of a bell 47 crash shortly after take off. The aircraft did not have a enough energy in the rotor disc to do an auto. I'll see if I can find the clip.
2nd- the Schoffmann is a tilt mast airframe. Configuration of a collective input control stick and routing of push/pull flex shafts will need to be addressed. You already have a forward,aft, lateral pulling and pushing motion to control the rotor discs and direction so how will this effect initiating an aotu should powere plant fail? That being said a typical up/down collective stick will not work otherwise you will have unintend pitch changes in the blades. Attention to overcorrecting is critical. Jusyt from what I've seen Auto-rotations are important to learn and get down. The second the power plant fails.........drop the collective all the way down.
Final thoughts, what is your end state goal/ Simply to build a helicopter and fly? With the Schoffman, you'll be able to hop around and fly 3 to 5 meters high, which is not a bad thing given that it's fixed pitch. But the Schoffman design may not be sufficient for the added weight of a collective system, which mean that you need to scale up. That being said, do you have the resources to scale up efficiently? I would suggest to never cut cornesr, never use materials/fasteners from the local hardware store unless you simply mounting a GPS. I'm not an expert or even an engineer, but I am mechanically inclined enough to know my own limits.......one day I will scale up my self, but only after crashing a few more RC scale models of my patent. Getting the bugs worked out is critical as well as safer in an RC scale. You're building a Schoffmann....already proven, but you're entering uncharterd waters with addtions to the design. I can only speculate the same as you do.