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Dec 11, 2009, 07:02 PM
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Venture Aeromarine Hovercraft


Does anyone remember a kit made by Venture Aeromarine? It was a nitro powered hovercraft made of wood. I had one and sold it on Ebay years ago as I never did get it to work correctly. Wish I had it back.
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Dec 29, 2020, 07:15 AM
Way to much free time!
CorvetteC5's Avatar
An older thread, however I finally have something to reply with!

I assembled my Challenger 1 Hovercraft, by Venture Aero-Marine, in 1982 from a kit. I have the construction manual and order form from my purchase. I did run it back then on electric power but with very limited success over an asphalt driveway, so into storage it went over decades.

Originally designed for a single glow engine of 0.09 to 0.15, there is room for only a 7 inch diameter prop, and it is heavily constructed out of plywood and spruce. Size wise it is about 20 inches wide by 25 inches long, not including triple-rudders. For this restoration to active duty, I installed a Skywalker 60A ESC and use it with 6-cell lipo batteries. Motor is Exceed RC 3025-760KV. Propeller is a 7 x 3.5 for glow engines. 6-cell battery is pieced from two 3-cell Hyperion 1600mah Graphene packs in series. Receiver is a OrangeRX with gyros, and the steering servo is a 12 gram metal gear that I was given.

This maiden run is encouraging and a disappointing. It steered quite responsively for a single motor Hovercraft! But the weak forward thrust is frustrating! Fortunately, there is ample margin for more propeller. After this 5 minute run, at mostly full throttle, both the motor and ESC were barely warm to my touch. A prop up-size will be tried next. A three blade 7x6 inch, or thereabouts, would be a good next move. Or even a cut down 9x6 3-blade wide blade, etc.

If more prop doesn't satisfy me then my plan-B is to add additional motors on ether side of the single one installed. Likely, they would be mounted at the very trailing edge of the hovercraft and aimed forward/rearward. These two new motors would turn propellers for forward thrust and differential steering. The current single motor would be used for lift only by closing off the exit of air blowing over the triple-rudders. Clearly explained, I hope!

This latest journey of tweaking and tuning an RC model should be fun!

Sincerely,
Curt

P.S. This maiden run was on Novembers 21, 2020.
RC Hovercraft - 1980's Challenger 1 - converted to electric power - maiden, 1 of 3 clips (6 min 16 sec)
Dec 29, 2020, 07:18 AM
Way to much free time!
CorvetteC5's Avatar
My Challenger 1 hovercraft with more electric power did well over asphalt and grass:
RC Hovercraft - 1980's design - converted to electric power - over 500 watts, 2 of 3 clips (5 min 47 sec)


I gave it a go over fresh snow:
RC Hovercraft - 1980's design - converted to electric power - over snow, 3 of 3 clips (4 min 5 sec)
Jan 01, 2021, 02:50 PM
Registered User
Can you post a few photos of the craft, especially at the back with the propeller and rudders? Just from eyeballing the design it doesn't seem great for forward thrust. Usually a single motor hovercraft has the prop vertical with 1/3rd of the propwash ducted to the skirt for lift and 2/3rds directed straight back through the rudders. Having the prop nearly horizontal introduces a lot of inefficiencies. Incoming air has to be slowed and turned into the prop disc, then immediately turned again to exit the back for thrust. All that introduces turbulence and drag that will sap the amount of power in the prop that finally ends up as thrust. Throwing more power at the problem doesn't really help either.

It looks like a good model to remake with foam, should save a huge amount of weight. If the prop could be angled a little closer to vertical that would also help things.
Jan 17, 2021, 07:05 AM
Way to much free time!
CorvetteC5's Avatar
Sorry for the slow reply. I just rediscovered this thread again. I should have pictures with me of this hovercraft and will post some, as you request, when I can gain access to them.

I appreciate your expertise into hovercraft design! I can't speak to the design philosophy of the Challenger 1 since it is not mine. When designed in the 1970's it was for glow power and all the vibrations and residue that come with it. An updated version from foam for electric power goodness could be in my future. Thanks!
Last edited by CorvetteC5; Jan 17, 2021 at 09:37 AM.
Jan 17, 2021, 09:35 AM
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FiftySlicks,

Attached are details of my Challenger 1 hovercraft, as requested. Included is my construction manual and flying instructions, scanned as PDF, that came with the kit purchase in 1982.

The angled propeller provides thrust into the usual three areas:
1) in the middle of the skirt onto the ground,
2) into the skirt for inflation, and
3) out of the stern through the trio of rudders for forward thrust.

That rather horizontal angle to the prop, as you identified, seems likely a result of the thrust to weight ratio of the design. Originally designed for a 0.15 glow engine, good for about 300 watts equivalent electrical power, mine is tuned for about 700 watts. It has never run more smoothly for me!
Last edited by CorvetteC5; Jan 17, 2021 at 09:56 AM.
Jan 19, 2021, 05:23 PM
Registered User
Thanks for the pictures. I can see a few problems but I don't think the fundamental design is that bad. It can certainly be made better while still keeping the horizontal propeller.

Rule of thumb for air distribution off the prop is 1/3rd lift and 2/3rds propulsion. The current layout is about 1/3rd lift and 1/3rd propulsion. There's a third missing and it's doing nothing. On the top view we can see the bottom third of the propeller open to the plenum beneath the craft, then the top third bleeding off air for thrust. The middle third is blowing air into the skirt and this is completely wasted power.

It's a bit counter-intuitive when I first encountered it - with a closed bag skirt you don't need any airflow into it after it's inflated. All that's needed is to maintain air pressure plus a small allowance for any leakage and short term variation as the skirt changes volume in motion. So actually that airflow into the skirt should be diverted to thrust. That alone will make a big difference. It's better to have a 400W motor with all the airflow properly used than a 700W motor with a third of the airflow doing nothing at all or causing lots of backpressure and stalling the prop.

The other thing about hovercraft is that the 'thrust' of the lift airflow is pretty meaningless. I have a dinky motor and 6" prop that puts out only a few hundred grams of thrust in the open air with 50W of power consumption. Used on a hovercraft as a lift motor it can easily support 5 whole kilograms without much of a struggle. So thrust/weight ratio doesn't apply for lift in the same way it would for a helicopter.

The other inefficiency here is turning the airflow from the prop horizontal for thrust. This isn't ideal but it can be made better. The propulsion airflow should be turned as gently as possible to horizontal. A nice curved scoop is far better than slamming the air into a sharp corner and spilling out with turbulence.

I've attached a sketch of how I would redesign the rear. I've also attached a photo of my own hovercraft showing the duct beneath the lift propeller. The small ports below the prop are all that's needed to inflate and pressurise the skirt.

On the venture hovercraft things are a bit harder. From the propeller, the lift airflow needs separated from the thrust first, then the lift air needs to encounter the pressurisation ports to the bag volume, then finally the lift air exits the bottom.

If you wanted to be clever (or too complicated!) we could have a servo driven flap to control the airflow split from the propeller. To hover on the spot throttle the motor down while diverting all the airflow to lift. For more forward thrust increase throttle while also reducing the airflow to lift. For maximum forward thrust have the motor at full power while reducing the split to lift as low as possible.

If it was me - I'd look to do a redesign in foam/balsa. All the problems can be ironed out with a big reduction in weight.
Jan 21, 2021, 06:37 AM
Way to much free time!
CorvetteC5's Avatar
Thank you!
May 09, 2021, 08:48 AM
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CorvetteC5's Avatar
Quote:
Originally Posted by FiftySlicks
Thanks for the pictures. I can see a few problems but I don't think the fundamental design is that bad. It can certainly be made better while still keeping the horizontal propeller.
FiftySlicks!

I worked from your suggestions for my Challenger 1 wood hovercraft, while keeping the rework respectful (minimal) of the 1980's design, and like the results. Presently, my changes have only been to the air ducting per your encouragement and tutelage. As shown in the pictures, 2/3 of the airflow that had gone inside the skirt and under the craft to raise it up is now redirected out of the back, through the triple rudders, for forward thrust. I simply glued in a couple pieces of 1/8" lite plywood to redirect the motor thrust. And sealed them with polyurethane. Check out the video (when it is done uploading and I attach it) speed is much higher now over the asphalt!

After this run I did discover fresh scuffing of the rip-stop nylon skirt. So reducing the lift thrust is causing accelerated wear to the fabric. At the moment I'm not sure yet if this trade-off is in a good balance. Time will tell!

Thanks for your help,
Curt

Venture Aero-Marine Challenger 1 wooden RC Hovercraft from the 1980's. 1-motor electrified (3 min 43 sec)
Last edited by CorvetteC5; May 09, 2021 at 02:25 PM.
Jul 30, 2021, 09:20 PM
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Venture Aeromarine Hovercraft


I got one of this for sell hit my dm if interested
(408) 508-3961
Aug 08, 2021, 12:40 PM
Way to much free time!
CorvetteC5's Avatar
Quote:
Originally Posted by Introtech
I got one of this for sell hit my dm if interested
(408) 508-3961
Which of their models are you selling? See included model product order form.

I see that you are located in Indiana too!
Last edited by CorvetteC5; Aug 12, 2021 at 06:55 AM.


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