Martian Posted April 3, 2020 Author Share Posted April 3, 2020 Duct sitting in place ready for glue Quote Link to comment Share on other sites More sharing options...
Martian Posted April 6, 2020 Author Share Posted April 6, 2020 Moving on or Hovering on, Rudder parts the rudder is an STL file from a 3d ugly stick but it does a perfect job Duct bonded in place and splitter plate extended with a smoothed of leading-edge I can soften glue to adjust if needed. (at this point my glue gun overheated and went pop it was only cheap and glue had leaked out and created an insulating jacket around the heat tube) there is also a rudder bearing plate at the bottom glued and sealed underneath the bottom deck will cover this Rudder mounted using a 1.5mm piano wire through the top of duct and rudder then through bearing plate to the bottom of the duct . Using a ball joint to the top-mounted servo that will be bonded to duct Top view More soon waiting for new glue gun Quote Link to comment Share on other sites More sharing options...
Martian Posted April 10, 2020 Author Share Posted April 10, 2020 Well, it's all but finished just the skirt to make or codge together somehow. The prop is next to useless so I am searching for a high-performance 5inch 3 or 4 blade one which might be a drone prop I don.t know anyone have any ideas it needs high thrust ? please feel free to comment good or bad some more piccies Lower deck and rx esc and lipo box cover not fitted Servo mounted at the top of duct works very well Holes in the sides to feed the skirt Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted April 11, 2020 Share Posted April 11, 2020 About 16/17 years ago we built the Griffon Hovercraft using 2 x 600 brushed motors running off 2 x 6 cell 2,000 mah sub C Nicds. We had the lift motor on an aircraft ESC operated by the throttle stick and drive fan used a boat esc (forward and reverse) using "elevator" stick. The skirt was made from lightweight ground sheet material, sewed together and glued on, it was fully sealed apart from a couple of ports into the lift duct to inflate it. It actually worked well on water and if the surface was pretty smooth we could drive on and off the water. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted April 11, 2020 Share Posted April 11, 2020 A very neat build but I fear as a "single motor craft" there will be an issue. A skirt needs "pressure" to inflate and resist the weight of the craft whereas thrust is obtained by airflow and mass where the actual pressure generated is tiny. Just an observation. Nothing wrong with experimenting. It will be interesting to see the result Quote Link to comment Share on other sites More sharing options...
Martian Posted May 2, 2020 Author Share Posted May 2, 2020 Finished the little one and it hovers yet to give it full beans. Simon you were right the prop would not give sufficient pressure then I remembered from my days around light hovercraft all the British ones had multi-bladed fans and the Americans used massive props a bit like their airboats so I tracked down some stl files for various fans and 3D printed some once I settled on the best I scaled it up printing it slow with maximum detail trouble is it got that much traction on the air it pulled the Collett of the motor shaft so I switched the motor round and used the bolt-on shaft. but it did work and now it will take higher rpm .The fan is 11 bladed and with the duct is somewhat like an EDF . The skirt although rudimentary work very well so hopefully in the next few days I can wind it up I see how it performs again. I should add since taking these pics I have increased the duct length to fully enclose the fan Edited By Martian on 02/05/2020 21:08:30 Quote Link to comment Share on other sites More sharing options...
Eric Robson Posted May 2, 2020 Share Posted May 2, 2020 Hi Martian, don't know if you do this already but can you vary the deflection of the airflow so that when there is enough to lift it more can be diverted to the rear for speed?. By the way the fan looks a lot better than the two bladed prop, keep your fingers clear! Quote Link to comment Share on other sites More sharing options...
Martian Posted May 3, 2020 Author Share Posted May 3, 2020 Thanks for commenting Eric. I could do that Eric but it does not warrant the time. There is plenty of lift now and speed is not a problem the problem is directional control in light hovercraft you lean into a turn with the rudder. but this needs three rudders I,m pretty certain the bigger hovercraft will have loads of control Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted May 3, 2020 Share Posted May 3, 2020 Martian I know absolutely nothing about hovercraft(s?), but that won't stop me from commenting. The rudder looks as though it will deflect the airflow from the EDF a little, but maybe not enough to push the rear end of the hovercraft around enough to steer it. Have you considered using "louvred" rudders, so that the majority of the EDF thrust is affected, rather than just a strip in the middle? By "louvred" I mean having maybe 3 separate rudders spread across the diameter of the circular fan outlet. Quote Link to comment Share on other sites More sharing options...
Martian Posted May 3, 2020 Author Share Posted May 3, 2020 Thanks Gary you are right as I stated in my comment above ordinarily in a light hovercraft body movement dictates the sharpness of the turn obviously that's not possible so accurate lateral balance is needed plus as you suggest at least 3 rudders of even better thrust vectoring Quote Link to comment Share on other sites More sharing options...
Christopher Morris 2 Posted June 2, 2020 Share Posted June 2, 2020 Will be watching this with interest, i am just starting one myself purely as an experiment. One thing i found that was interesting. Many intakes for the lifting motor have a large flange like a doughnut with a flat bottom. This acts as a wing & when the air is sucked in over the edges, it creates a low-pressure area above & with the high-pressure underneath & creates lift. So the answer to all problems is doughnuts.. LOL but its true. Quote Link to comment Share on other sites More sharing options...
Martian Posted June 2, 2020 Author Share Posted June 2, 2020 Hi Christopher welcome to the Hover area you can post your progress on here if you want or do your own build log and yes a donut is an answer to everything LOL I can always make modifications if needed. I have been in the doldrums for a while ridiculous I know with all this build time I keep trying to get back in the grove well you all know how it is. Anyway, I have made progress on both Hovercraft the small one is complete and works well you can see from the pics the rudder arrangement has been changed also a new duct with a slight rearward down angle, now the kids are back at school (not mine ) that frees up a large flat tarmac area and I want to video it in action. The larger Hovercraft known as Large lol requires the skirt making and fitting I have printed a large fan blade that seriously moves some air I had fitted it using a compression fitting on the shaft at half throttle the fan lifted itself off the shaft and went spinning up in the air about a meter it was fascinating to watch it spinning in the air before it slowed down enough to lose lift. I am unable to change the shaft around to fit a screw adaptor so I am in the middle of fitting another motor. Some pics So onwards Quote Link to comment Share on other sites More sharing options...
Martian Posted June 2, 2020 Author Share Posted June 2, 2020 Missed one the EDF with swivel duct Quote Link to comment Share on other sites More sharing options...
Eric Robson Posted June 2, 2020 Share Posted June 2, 2020 Good to see you modelling again Martian,I see you still have 2012 on the camera. I hope it goes better for you this time, beware of flying fans. Cheers Eric. Quote Link to comment Share on other sites More sharing options...
Martian Posted June 2, 2020 Author Share Posted June 2, 2020 Thanks Eric , I can't be bothered to reset the date every time I remove the card it's just easier that way Quote Link to comment Share on other sites More sharing options...
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