Originally Posted by JeremyBB

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?

Yes thats it, its the ports that give you the sideways thrust, Puffports is what iv been informed that they are called.

A few more pics of the build underway. The deck ribs are made from 2mm lime strip, curved where necessary using a Mantua Models strip bending tool. The top of the cabin front is made from blue polystyrene overlaid with 0.6oz/m2 fibreglass cloth coated with DeLuxe Materials Eze-Kote resin. This is very lightweight and protects the soft PS from knocks. I will use the same materials to strengthen the tail fins and ailerons which will be made from balsa sheet. The lift duct is from 0.4mm birch ply, same as used on the decks.

Wow, very nice. Can't wait to see how this turns out

Originally Posted by JeremyBB

A few more pics of the build underway. The deck ribs are made from 2mm lime strip, curved where necessary using a Mantua Models strip bending tool. The top of the cabin front is made from blue polystyrene overlaid with 0.6oz/m2 fibreglass cloth coated with DeLuxe Materials Eze-Kote resin. This is very lightweight and protects the soft PS from knocks. I will use the same materials to strengthen the tail fins and ailerons which will be made from balsa sheet. The lift duct is from 0.4mm birch ply, same as used on the decks.

Hi Jeremy, pics look great. Just one question, what did you baes the diamater of the lift duct on, it looks larger than others that i have seen ??

Hi gents, do any of you have the info on the lift fan build, plans ect ect or even the details of any off the shelf fans that you can buy ??. Iv been looking at tumble dryer fans as maybe a good source, thoughts ?????

After the success of my home made fan try a DIY job. Otherwise, stick to a prop. I dont think there is much in the way of off the shelf items that would really suite. If you want more info let me know.

Originally Posted by PITPUP

Hi Jeremy, pics look great. Just one question, what did you baes the diamater of the lift duct on, it looks larger than others that i have seen ??

The duct is 6" diameter as on the plan from which the model is made. The original was powered with an RS540 motor driving a 6"x4 two bladed propellor. With a more powerful and lighter brushless motor, I could probably have gone with a smaller duct. However, as this is my first Hovercraft, I decided to stick with the plan. If I were starting over again, I probably would have cut it back to 5". The thrust motor on the original was also an RS540 so I will get more power and less weight using a brushless there as well. I have faired in the top of the duct as shown in the pic below which hopefully will help disguise it being oversized and get a bit closer to the prototype.

I suspect that the other models you have seen may be using an impeller rather than a propellor for lift (as on the prototype) which will be of a smaller diameter.

Originally Posted by ChrisCurry

Here is the kit I'm building for my daughter. The fan has come out far better than mine. I might steal it you can see bottom middle my special tools - the blade angle thing on the left, the blade length cutting jig in the middle and the window cutter on the right. Two hovercraft at the same time works quite well.

Chris, where did you get this kit from ????

Originally Posted by ChrisCurry

After the success of my home made fan try a DIY job. Otherwise, stick to a prop. I dont think there is much in the way of off the shelf items that would really suite. If you want more info let me know.

Chris, couple of questions if you dont mind. 1st what is the scale of your model ?, 2nd, what is the radius or dia of your lift fan ??

Many Thanks

Pitpup, most folks tend to stick with off-the-shelf props or make a centrifugal fan out of ply/ balsa. The latter is trickier because they are hard to balance, but if you are very careful with you construction it is eminently possible.
The problem with other types of fans is that they tend to be either too heavy, not designed to cope with higher revs or are aerodynamically less efficient in this application (particularly due to the back pressure). I know that some people have successfully adapted fans from devices such as car heater fans and appliances, but it inevitably leads to more work and less satisfactory results.

Ok question to everyone . what is the best way to maintain access to the lift fan motor should it be needed ?. Once the rear area construction is complete it appears that it is all sealed and no access is available. how have you all approached this issue ?. Cheers.

Originally Posted by JeremyBB

The duct is 6" diameter as on the plan from which the model is made. The original was powered with an RS540 motor driving a 6"x4 two bladed propellor. With a more powerful and lighter brushless motor, I could probably have gone with a smaller duct. However, as this is my first Hovercraft, I decided to stick with the plan. If I were starting over again, I probably would have cut it back to 5". The thrust motor on the original was also an RS540 so I will get more power and less weight using a brushless there as well. I have faired in the top of the duct as shown in the pic below which hopefully will help disguise it being oversized and get a bit closer to the prototype.

I suspect that the other models you have seen may be using an impeller rather than a propellor for lift (as on the prototype) which will be of a smaller diameter.

Thanks for the reply, i am building an impelled for the lift fan to the diametions as detailed in mark porters book on hovercraft. it looking a little small so was thinking it might be for a 16th model as is the plan, Im making a 12th one so think ill scale the dimensions up and see what it looks like.

Few pics of my recently completed lift fan. Going to make a second one from plastic, will post when complete.

Originally Posted by PITPUP

Chris, where did you get this kit from ????

I am making a kit for my daughter from the plan

Originally Posted by PITPUP

Chris, couple of questions if you dont mind. 1st what is the scale of your model ?, 2nd, what is the radius or dia of your lift fan ??

Many Thanks

I believe mine is 1/16th scale. Just over a meter long. The width of the body is 16cm so i mafde the fan 14cm to allow some clearence. The central hole is 10cm - the diameter of a convenient mayonaise bottle that i used to make the duct.