View Full Version : At long last!

srn4 - n/a
11-May-06, 03:11 PM
Well today was the second flight of the monster!

Appart from a slight overheating problem and a broken steering cable mount (again) things went really well...

It actualy flies a lot better with two heavy people in it than with a lightweight like me on my own http://hovercraft.org.uk/images/icons/smiley_icons/icon_rolleyes.gif

I think I will have to add a second steering cable to try and decrease the stress on indavidual components because at full chat i am struggling to move the rudders http://hovercraft.org.uk/images/icons/smiley_icons/icon_confused.gif


Video to follow as soon as my laptop repairs itself!

jon_curtis - n/a
11-May-06, 05:35 PM
looks good mate!

little pointer regards the steering, well the rudders really! if at full chat you cant turn the steering, and or it turns better in one direction than the other! then your rudders are not balanced. putting on another cable with help you, but its not solving the problem! one push pull morse cable should be enought to do the rudders. so take a look at them, and set them up so they are balanced, it will give better steering response also! if you dont know what i mean about a balanced (aerofoil) rudder. then will email you a diagram!

srn4 - n/a
11-May-06, 07:44 PM
Yes, please email me a diagram http://hovercraft.org.uk/images/icons/smiley_icons/icon_sad.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_confused.gif



jar2 - n/a
11-May-06, 08:09 PM
It's not complicated, Duncan. The distance from the rudder pivot to the leading edge should be 20-23% of the total rudder width (assuming a reasonable aerofoil shaped rudder).

Even if the rudder is balanced it can still be difficult to move when the craft is unbalanced, as it is during a side-slip in a cross wind - the only solution in that situation is to back off the thrust momentarily.

tonybroad - n/a
11-May-06, 08:46 PM
i recently had a rudder problem, someone advised i move the pivot to 1/5th length of the rudder - problem was solved and rudder now self-centres well and operates correctly

the 1/5th distance means some of your thrust air assissts the rudder in turning and therefore takes effort off your cable

hope that helps and well done on your maiden voyage


srn4 - n/a
11-May-06, 09:21 PM
My rudders are already setup like that though....

I think..

See attached photo...(black line is the pivot point)


jar2 - n/a
12-May-06, 08:17 AM

It certainly looks like they are pivoted around the correct place, However,, after seeing the big angle cut from the front, I should clarify my 20%, to be 20% of the area of the rudder should be in front of the pivot. You can expierment with the overhang by using bits of cardboard taped the the front or rear edges to extend them a bit (it should last long enough to give you an idea).

It may be worth checking the pivots aren't binding when thrust is applied to the front rudder edge.

If none of these things work then you'll just have to eat more spinach http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif

srn4 - n/a
12-May-06, 08:27 AM
Maybe if I describe how the steering feels it might help?

With the rudders sraight at full chat you really have to give it some efort to get them to turn, and then once they are turned they move ok.

any thoughts?

Do you think its worth addind a second cable so they are pull pull rather than trying to push?


jar2 - n/a
12-May-06, 08:47 AM
I would say that is pretty normal, Dunc. At the straight ahead position you don't get much "power-assisted" effect. As I said before, I tend to back off the thrust a bit then apply full rudder followed by thrust again to swing the back end around quickly. No doubt everyone has developed their own technique.

You shouldn't need an extra cable unless you have a huge amount of thrust. Hovercraft rudders are not what I would call a precision steering device - a bit of slop in the linkage and pivots really make very little difference in actual operation.

One last obvious question - have you got the cable attached at 90 degrees to both the rudder and control when they are in the straight ahead position? If not, it could be hard to get the rudders mving from this position in one direction.

BTW I assume the fan blades weren't set properly in the above pic? It looks more like a paddle steamer than a hovercraft http://hovercraft.org.uk/images/icons/smiley_icons/icon_biggrin.gif

Sean Atterbury - n/a
12-May-06, 09:05 AM
Well Done man http://hovercraft.org.uk/images/icons/smiley_icons/icon_biggrin.gif

Now that your up and running, working through the kinks is a lot of fun. http://hovercraft.org.uk/images/icons/smiley_icons/icon_mad.gif

Once that part is done then just finding the time to get out and enjoy will be the next on the list, you are lucky to have the club and then you can go with them, I have however hav'nt been out for months, just cant seem to get away from the house.

Hope that you get it sorted soon and would love to see the craft going in one of those video's you talked about.

Happy Hovering. http://hovercraft.org.uk/images/icons/smiley_icons/icon_biggrin.gif

srn4 - n/a
12-May-06, 09:07 AM
Heehee...only just noticed the fan in that photo...yes I have adjusted the pitch just slightly from that position...even the beast of a subaru engine wouldnt cope with that much pitch http://hovercraft.org.uk/images/icons/smiley_icons/icon_lol.gif

Just been down to the garage to have another look and I wonder if one of the problems is down to a cheap steering cable...

And yes, the cables are at 90 degrees front and back when in the neutral position.


Sean Atterbury - n/a
12-May-06, 09:14 AM
You know, mine did the same in the beginning, is it not just sticking a bit there in the rest position, give it a wiggle, mine came good after a few vigerous viggles, seemed to just catch on something like old paint.

Other than that, I'd say it all looks fine to me.

PS: a remark from Danger is most probebly going to follow. Lets all wait in antisipation.. http://hovercraft.org.uk/images/icons/smiley_icons/icon_eek.gif