Espritmodel.com Telemetry Radio
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Old Apr 03, 2012, 11:15 AM
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JCPWEBB i found them on google, why do you ask ???
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Old Apr 03, 2012, 11:25 AM
Barefeet
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I am thinking about it but not quite sure how to proceed. It seems to go fine without so maybe I'll just leave it.
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Old Apr 03, 2012, 11:33 AM
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thanks for the reply Chris, do you have any detail photos or vids to share ??. Im not sure if you have seen them but i posted some of my build to date eairler in this thread.
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Old Apr 03, 2012, 11:39 AM
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Quote:
Originally Posted by PITPUP View Post
JCPWEBB i found them on google, why do you ask ???
Just wondered the source - they look like they have been CNC'd to me, which is not ideal for most people unless you use a send and make service, but I know a few folk do have CNC machines at their disposal. The more common approach is like Chris here, i.e. create a disc, mark it out and cut straight blades that are glued in place (usually it is good to make a jig to make sure it's as balanced as possible). I tried to make a backward curved bladed fan using HIPS, but I found the plastic weld warped the plastic to such a degree that the fan was all wobbly. I may try a hybrid approach using ply for the back and ring and HIPS for the blades (I've already built a jig to hold the blades in a curve).
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Old Apr 03, 2012, 01:50 PM
Barefeet
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Pitpup, I did see your build you are building far nicer than I have. I used half the ribs as I am a lazy builder and cutting them out by hand took too long so my structure is simpler.
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Old Apr 03, 2012, 02:25 PM
Barefeet
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Quote:
Originally Posted by jpcwebb View Post
Just wondered the source - they look like they have been CNC'd to me, which is not ideal for most people unless you use a send and make service, but I know a few folk do have CNC machines at their disposal. The more common approach is like Chris here, i.e. create a disc, mark it out and cut straight blades that are glued in place (usually it is good to make a jig to make sure it's as balanced as possible). I tried to make a backward curved bladed fan using HIPS, but I found the plastic weld warped the plastic to such a degree that the fan was all wobbly. I may try a hybrid approach using ply for the back and ring and HIPS for the blades (I've already built a jig to hold the blades in a curve).
I would keep it simple and just build one to see. It's a quick process so you can knock out a fan in around an hour.

Earlier I think JeremyBB said that the skirt can be closed if a fan is used but it needs holes in it - you should be able to see from one of my earlier pictures - post#28 - there is a row of holes along the inside of the skirt where it attaches to the bottom of the craft that creates the lift. I just marked the spacing and used a soldering iron as the fabric seems to be synthetic and I managed to make the holes easily.
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Old Apr 03, 2012, 02:28 PM
Barefeet
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Here is the link to the ductedfan version http://www.hoverpower.de/index2.html - beautiful boat...
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Old Apr 03, 2012, 02:31 PM
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Correct - there must be a route for the air to get into the plenum. The two options are to duct it in directly, or if you have enough air pressure and flow rate, though the skirt. Of course on the full size craft, the skirts are not bags but C-sections, so there is nothing to stop the air between the bag and the plenum.
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Old Apr 04, 2012, 11:16 AM
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I don't like threads like this - because now I have to add a hovercraft to the build list Amazing stuff guys!
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Old Apr 05, 2012, 11:50 AM
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Progress update

Basic structure complete. Next step will be to skin the decks and cabin roof. It all takes time!
Pitpup - what scale are you building to?
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Old Apr 11, 2012, 01:43 PM
Barefeet
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Looking good. Are you going to skin the deck with ply?
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Old Apr 11, 2012, 01:46 PM
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What brushed motors and props to be used?

I'm at the point in the build where I need to decide on my motor/prop combinations for thrust and lift. Mark Porter's original plan was based on brushed 540 motors but I would like to use brushless motors for both thrust and lift (more power/less weight). Batteries will be 7.2V NiMh packs.

The plan showed a 3 bladed 6*3 prop for thrust. I have to stick to 6" to match the diameter of the lift air duct and have found a 6"4 3 bladed prop from Flightline which might be OK. The plan showed a 2 bladed 6*4 prop for thrust but I would prefer to use a 4 bladed prop as on the prototype with a diameter closer to that on the prototype which looks to be somewhat smaller.

The plan shows the lift motor mounted below the prop which itself is roughly at the level of the top of the cabin windows. The Tony Middleton & Fran Oakey DVD suggests that the prop should be positioned level with the top of the air outlet into the skirt which is much lower. If the dimensions were OK, I could mount the lift motor to the underside of the 1/8" ply former on which the thrust motor is mounted in the Mark's plan with the prop below the motor.

The attached photos show where I have got to so far. The 6" diameter lift duct will be made from 0.4mm ply formed round a 6" plastic pipe which would then be removed. If the lift motor cannot be mounted on 1/8th ply former, I would require some strengthening in the side frames to take a motor mount.

I would very much appreciate advice on the specifications of the brushed motors and props to be used for this model and ideally recommendations for actual units/suppliers. Any thoughts on mounting arrangements would also be helpful.

Jeremy
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Old Apr 11, 2012, 02:15 PM
Barefeet
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I would guess that you need a motor that can spin the lift prop at about 10,000 rpm - Around 1400kv - and for that size prop probably a 100w motor will be fine. Something along the lines of a hobbyking turnigy would do the job - like this - http://www.hobbyking.com/hobbyking/s...Outrunner.html - can take more amps but is dirt cheap. Or even this - http://www.hobbyking.com/hobbyking/s...%5F1350kv.html
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Old Apr 11, 2012, 02:27 PM
Barefeet
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Or this motor - http://www.hobbyking.com/hobbyking/s...%5F1700kv.html - a classic motor
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Old Apr 14, 2012, 04:00 AM
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Pitpup sent me the following message:

Hi, i was just wondering if you have any detail photos that you could post of the underside of your craft in the area of the rear puffports/pannier tanks. I am having a little trouble working out how the underside is constructed and would value some help.i few simple pics in this area without the skirt should just be the job, hope you can help.

As I see no option to attach photos to private message replies, I have taken the liberty of replying here. Anyway, others may also be able to help better than I can.

I attach a few photos of the relevant area below which hopefully clarify the construction method. Incidentally, puffports is a new term to me - does it refer to the ports which will run from the lift duct (not yet installed), through the side frames and into the panniers?
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