Thanks for the link to MakerPipe Mr.Jadkowski. It looks ideal for a different project I’m working on, but I’ve never seen it here in Australia. I’ll make enquires through the website. Serendipity!
Cheers
Those maker pipe couplings are strong! Before I put the net on I put that frame hoop-down on the ground and stood on the back of it.
You can’t keep a good man down! Did you have access to some rollers to make your cage or did you manage somehow with your conduit bender?
I got a tubing roller from Harbor Freight to do the hoop. It took a few tries to get one that came out straight. What finally worked was to put the roller on the floor and use a bunch of plywood and other stuff to shim the tubing so it stayed on the same plane as it passed through the roller. As it began to curl around I was shifting all the stuff to keep it under the tube. I wasted 20 feet of tubing figuring that out, so if you plan to try the same thing I would get some extra material!
I riveted the net to the cage. Turned out great!
Edit: thanks to @GliderPilot for the inspiration to make my own dyneema net. It cost me a grand total of $13 for the twine and two netting needles, and it only took a couple of hours once I got into a good rhythm. Not only was it cheap and easy to make, but I was able to size it perfectly for my cage.
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I did a quick hang check with my Little Cloud Turtle seat harness, to eyeball the thrust line vs. carabiners. So far so good! Once I have the motor and everything else installed it will hang back a little farther, but the thrust should be pushing me more upright against the chest strap/reserve container. I’ll have to think of a good way to secure the loose material in the back so it doesn’t poke through the frame like it is in the picture.
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I worked a little on the motor mount today. The crossbars are made from 1/8" aluminum angle stock, the spacers are 2" aluminum from McMaster Carr, and the machined mount came from Neumotor. Eventually that will all get assembled with Arctic Silver 5 thermal paste to (hopefully) facilitate some heat sinking from the motor out into the mount.
My motor mount and battery racks are done. The mount came together just as I had planned. The battery racks are made from 2"x2"1/16" aluminum angle stock, riveted together and to the frame. The racks won’t actually support the weight of the batteries; that will be done by two battery straps per rack. There is Velcro on the faces of the rack just to make loading the batteries easier and for an extra level of security in case a strap (or both straps) fail.
I decided to mount the battery cutoff switch/throttle arming switch on the right side of the frame above my shoulder. That puts it in an easy to access spot for my right hand, so I can get to it without taking my hand off the brake.
My UF3812L 38x12 props showed up from China. The balance seems very close and I’ll probably run one on the motor before I do any more balancing. I think it might take one extra washer under one prop bolt to get it perfect. Like most things on this project, they are both huge, and not quite as large as I expected.
My motor controller is on its way to APD in Australia to fix the faulty current logging. They are either going to fix it, or replace it. I’ll finish all the power wiring in the meantime, and once it returns I should be ready for ground testing.
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I’m working on the wiring now. It’ll be nice to ditch 75% of my power wiring with the short distances between the batteries, power switch, and motor controller. The new prop fits nicely. I may add a spacer between the prop and the hub flange to push it back a little more. Right now there is about 2" of clearance between the prop and the cage.
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I’m still plugging away at this. My motor controller should be on its way back from APD in Australia, so I’m hoping to get the motor spinning again in a week or two. In the meantime, I’ve been playing with the suspension and I have realized that my original plan of wearing the unit over the top of my lightweight mountain harness is not going to work. The carabiners are too far forward, so the hang angle is much too far back.
I played around with adding some extra straps to connect the motor frame to the carabiners, but I can’t find a good position to connect them that actually shifts the carabiners back and the frame upright without adversely affecting the seat of the harness. I had my friend push on the motor while I was hanging to simulate the effect of thrust and it does bring me more upright, but it’s also pushing my chest into the chest strap and I suspect it wouldn’t be very comfortable after a few minutes.
As a result of all that, I have decided to add some swingarms and a conventional PPG harness. Our local PPG dealer (Skysports USA) has agreed to loan me an Apco split leg harness to experiment with. If I can get it all working, then I’ll buy it from him. It is going to add another $700 or so to the cost of the rig (harness plus another reserve plus a reserve container), but an added benefit is that the whole thing will probably weigh 1 kg less than using my mountain harness and the backpack straps. The plan is to bend some Miniplane ABM-style swingarms out of the same 3/4" aluminum EMT I used for the frame.
Another small detail is that I added a bottom piece to the frame to bridge the open gap. I had planned on covering the gap with either a plate or a net, but I realized that because the plate or net wouldn’t follow the contour of the hoop it would be just mm from the tip of the prop. The prop would also be very very close to the ground if the frame was sitting on the ground and the prop spun. I just cut a chunk out of my failed attempts at rolling a hoop, and slid it into the tubing couplers at the bottom. Seems just as solid as the rest of the frame.
hello, a note. you have 2 tubes behind your back that should be cut off. there the line can hang from the rescue parachute. or line with a full stall. it can also happen that if you fall forward the tube hurts your head. just meant as a hint. regards
Good point; that was already my plan. I just need to move my electrical control box down the frame somewhere.
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Hi, Thank You
I decided on the impress 3 because it is the best of the quality. Although it is 1 kg heavier than the current pod harness of this class, only the best material is used. From the geometry it is possible to fly exactly the same setting of the scales as with thermal flight in mountains. the container underneath the pilot is therefore perfect for the battery. the shape is optimal to save electricity. it also works with other pod harness. but the most important point is now why i love impress 3 so much … there was a competion pod which is already prepared for the rescue parachute. aerodynamically integrated in front of the pilot and with area for the flight instruments. there are motors from geiger, rotex, hacker that are designed for eppg from europe. there are also similar engines in china. However, I haven’t seen anyone today that is comparable in performance with European engines. it is the same with the esc. Here are leading companies from Germany and Czech. There are folding propellers for Geiger motors that Toni Roth makes in Germany. you can buy them. all other eppg pilots, like me, build their own propellers themselves. but i think e-props will soon bring a folding propeller with 125 cm / 130 onto the market.
My project came to an end today. I got my motor controller back from APD, installed it in the frame, powered it up, and shortly after I started spinning the prop at low throttle the controller shorted internally and burst into flame. It was completely destroyed, along with two batteries (didn’t ignite but the labels are burned off so I presume the cells are heat damaged) and likely my motor as well.
I could probably rebuild this but I’ve dumped enough money into this project that I’m just done with it. After watching that controller go from fine to full-on inferno in seconds, I don’t want to be anywhere near that thing in flight. I’m just disappointed that I never got to see if it would actually fly.
I feel you ! Sorry to see that…I was wondering if that esc should not have some protection ? I don’t know what to say… Regards
I know that feeling. My own project is in the very back of the garage after a catastrophic failure (poorly designed cage pushed through the prop on launch).
Commiserations, Paul
I’m sorry for what happened to you!
below I would like to list a few technical things.
very often you can see similar examples if rc material is used for drives that are too large and burn. not by the current in the drive itself. the esc switches off the much too high phase currents. (if the motor is undersized and the propeller is too large, phase currents will already occur at half throttle of several hundred amperes in the esc). the drive is still rotating and generates a few kilowatts of power which then come back into the esc and bring everything to melt in a few milliseconds and it burns. Therefore esc suitable for aviation have always programmed an active freewheel so that there is no problem with recuperation. Even if you put together the wrong setup for aviation esc, there is no fire because the esc automatically detects it long before an overload occurs and then a fault occurs. if you do it 3 times, it will not start. then only the manufacturer can unlock the esc. this serves the safety of the user if he does not have enough expertise about electric drives.
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This ESC has all of those features; active freewheeling, and bus and phase current limiting. I sent the ESC back to APD to fix a problem with the current measurement in the logging. They did test it before it left their shop, but I suspect that something wasn’t assembled quite right in the ESC after the repair and the vibration from the motor and propeller caused something to come loose and bridged some contacts internally to cause the short. It wasn’t your typical pop + smoke ESC failure. This was a VERY energetic electrical fire.
APD has offered to replace the controller, but as I said before I’m just not interested in continuing the project. I’m hoping that I can at least get a refund from them so I can recoup a little bit of what I’ve spent. That controller was the single most expensive component on the whole machine.
Big bummer. Do not think about it for a moment, grab a few beers and perhaps after some days the damage appears less than you think now.
Here is the other half of me abandoning this project:
Originally I decided to build this because I was sick of having to drive 4+ hours round trip every time I wanted to go flying. All of the closest free flight sites to me are a two hour drive. However, over the course of the winter I figured out how to fly the mountain behind my house. Now I can do a hike-and-fly that takes me 1 hour, from door to door. I don’t even have to pack up my wing; I can land, rosette, and walk right to my house. It is also proving to be a fairly reliable site with multiple flyable days a week. So I really don’t need this motor for my original intended purpose anymore. Honestly my real interest has always been free flying and soaring; the motor was just a subsitute. I don’t think I need the substitute anymore.
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Just posting a quick update to say that APD refunded me what I paid for the motor controller ($989) so at least it wasn’t a total loss. I sent the motor back to Neumotor to be inspected and it checked out, so no damage there. If anyone is looking for a cheap jumping-off point for a project I’ll sell the 8057/75 motor, motor mount plate, prop adapter, 2" prop extension, and two 38x12" carbon propellers for $350. I think I paid around $760 for all that stuff.