PDA

View Full Version : Multi-wing blade lengths



Sean Atterbury - n/a
9-Oct-06, 09:25 AM
OK, So it went BANG!!!!!!!!!!!!!



http://hovercraft.org.uk/images/icons/smiley_icons/icon_mad.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_mad.gif http://hovercraft.org.uk/images/icons/smiley_icons/icon_mad.gif



So I was thinking, http://hovercraft.org.uk/images/icons/smiley_icons/icon_rolleyes.gif First, Y did it go BANG, No clue, but it took the belt and 3 blades with it.



I was loading it onto the trailer and was about half way up and resting on the hull when it happened, I think it that the hull flaexed too much or something and the belt flew off and broke, taking the blaedes with it.



So I have decided to revamp everything in that area.



I am using 4Z blades at the moment with a 30cm blade that gives me a diameter of 850mm with hub...



The duct is almost 900mm, some may remember some of my previous problems of tip clearance, well while it is broken I thaught I mite as well try fix it.



What blades can I get that are longer than these to fill the duct and will still fit the hub. OH its a 9 blade hub from Multi-wing too.



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



The pic is of the damage, the yellow stuff is the foam that I put in to fill the gap betwen the blade and duct. I want to take that out now if I can get the blades I need.



Thanks.

Iceman - n/a
9-Oct-06, 12:46 PM
Hi,



you need to use 5Z blades which are much longer than the 4Z's. Also ask for the white blades, they are much stronger than the black ones and can absorb impact from almost anything!



Looking at your photo, I assume the belt actually snapped because with flanges on both top and bottom pulleys, even with excessive slackness and flexing, I couldn't imagine it jumping off?



Having looked at the photo again, I think I can see your problem, the horizontal box section appears very close to the fan, with a bit of whipping of the blades, it is possible for them to hit the frame and that is obviously going to break them. Look for impact damage on the frame and if you can see any, try and replace that cross piece with something that gives more clearance (and ideally a bit more aerodynamic!!).

Hovertrekker - n/a
9-Oct-06, 01:20 PM
How was the belt tension? They need to be pretty tight or the whipping action will break them cleanly. I'd recommend a Gates Polychain GT2 over a Jason belt. The 5Z blades are wider chord so you'll have to use less pitch probably to absorb that same power.

Sean Atterbury - n/a
9-Oct-06, 02:03 PM
OK, checked the mounts and there is no signs of it hitting.



I checked the clearance a while back and it is good, but not very earodynamic, will maybe change it, have to still decide when the blades come. Being longer the clearance will thus be less, so will check that later.



The belt is a HTD 1360 8M Jason. Maybe you guys can be realy nice and get me a price on them over there, I will have to fork out over 600 rands here for it and that is plenty for my budget.



The tension was good, I check it regularly and would only twist to 90 and not past.



Anything els?

kach22i - n/a
9-Oct-06, 02:25 PM
Dang, and I thought I went crazy with spray foam. Did that gray paint help seal it at all?



I found the best tool for carving that soft foam to be a bread knife I picked up from the "Dollar Store".



"Great Stuff" or spray can foams do absorb water, right out of the air sometimes.

Don83000 - n/a
9-Oct-06, 03:23 PM
At 600 rand by the time you pay postage I doubt you are going to save enough to worry about.Try screwing them for a bit better discount.

Sean Atterbury - n/a
10-Oct-06, 06:12 AM
Yip that foam is great stuff, I used a hacksaw clade then smoothed it off with the small grinder, the grey stuff was black and well, just goes to show what forces of air and stuff work there, to take the paint off like that and even some of the foam, the air must move realy quick.



About the belt, they tell me that they import them and thus the price, maybe I could get it cheeper from Conrad, will send him some mail, only need to have everything done by December so plenty of time.

Sean Atterbury - n/a
10-Oct-06, 07:14 AM
Bugger, Louis says that it is going to cost about the same to get it here than it import, so I guess that I will bite the bullet and just get it.



The blades are no joke either, the 4Z were when I got then 60 bucks each, these 5Z are 140 each, man they are not scared or anything here, still not as bad as the belt though.



What would be the best way to cut the blades, when they get here, I was thinking, chuck then with the hub on the bench and mount the grinder in a ficed possition, then just turn the fan slow.



Good or bad idea?

Nickinoue - n/a
10-Oct-06, 12:46 PM
Hi atters,

I basically got my blades on the hub, calculated the length and added a few mm for good measure. Mounted the hub on a flat piece of wood the right distance away from the band saw blade.I then mounted the fan on the mount inside the duct and saw how much i needed to cut off! then just slowly cut bit by bit. Make sure the blades are at the angle they will be on the craft when u put it in the saw! this means u get perfect radius cut edges and small tip clearance http://hovercraft.org.uk/images/icons/smiley_icons/icon_razz.gif

Good luck

Nick

Sean Atterbury - n/a
10-Oct-06, 03:23 PM
Thanks Nick, will do http://hovercraft.org.uk/images/icons/smiley_icons/icon_biggrin.gif

wingfangb - n/a
26-Oct-06, 06:30 PM
WingFan GB Ltd have just opened in the UK. They can supply P5Z blades and a new P6Z blade in Polyamide material, these will fit your application.

The P6Z blade is unique to WingFan. It has a wider blade width than the P5Z but still fits the Z type hubs. Please go to www.wingfan.co.uk for full details

Tel No. 0116 2662889 or 07932 628412