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Old 15th May 2014, 08:02   #1
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Wink Sourcing an engine for a Hovercraft

I am planning to design a hovercraft sort of a vehicle as a science project. My rough power requirement calculations for the weight I have in mind is about 50 - 60 hp

Which car engine would be best suited for this requirement in terms of:-
(a) Best weight to power ratio
(b) Track record of good performance on roads
(c) Maintainability

Three other question I have on this same subject are:-
(a) Can I walk to the car dealer of the car whose engine you might recommend and can I ask him to sell me just the engine or will I have to get from the second hand market

(b) Since the requirement to drive a propeller, clearly the throttle - rpm control is crucial. If I took the gearbox out (to make the design lighter) what kind of optimal rpm can I expect out of one of these engines (to help me decide the gearing between engine and propeller).

(c) How much would one of these engines with battery and alternator (but without the gearbox) typically weigh?

Any advice would be helpful. Thanks in advance.
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Old 15th May 2014, 12:56   #2
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Default re: Sourcing an engine for a Hovercraft

Quote:
Originally Posted by rramesh_68 View Post
I am planning to design a hovercraft sort of a vehicle as a science project. My rough power requirement calculations for the weight I have in mind is about 50 - 60 hp

Which car engine would be best suited for this requirement in terms of:-
(a) Best weight to power ratio
(b) Track record of good performance on roads
(c) Maintainability
The best option i can think as of now will be the 1000cc K series engine from Maruti. Its one of the most light weight, reliable, powerful and pocket friendly engine.

Quote:
Originally Posted by rramesh_68 View Post
Three other question I have on this same subject are:-
(a) Can I walk to the car dealer of the car whose engine you might recommend and can I ask him to sell me just the engine or will I have to get from the second hand market
Both are possible option's.

Quote:
Originally Posted by rramesh_68 View Post
(b) Since the requirement to drive a propeller, clearly the throttle - rpm control is crucial. If I took the gearbox out (to make the design lighter) what kind of optimal rpm can I expect out of one of these engines (to help me decide the gearing between engine and propeller).
This engine can be revved till 6,000 rpm in the cars its been used. Ofcoures the car maufactures have set a rev limiter at 6,000rpm. So it can be revved more if no rev limiter is used. But that may shorten the optimum engine life.

Quote:
Originally Posted by rramesh_68 View Post
(c) How much would one of these engines with battery and alternator (but without the gearbox) typically weigh?
I cant exactly comment on the weight of this engine alone but i can assure you its one of the most light weight engine available in the market. Its an all aluminum set up to decrease the weight of the engine. Let me tell you this engine churns out a power to weight ratio of 91bhp/ton in a maruti Alto k10 which weights around 770kg and this engine churns out 67bhp with 90Nm of torque. So this may help you to do some of your calculations.

Lastly all the best for your project.

Last edited by Samba : 15th May 2014 at 13:04.
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Old 15th May 2014, 13:58   #3
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Default Re: Weight to Power Ratio considerations

Thanks for the input. On the question about the weight, I was able to ascertain the kerb weight of a number of cars vs their engine power.

In fact after having downloaded an Excel sheet that someone had carefully put together, I had a fair idea of the kind of output power available in the market. What I could not find out was the weight of just the engine alone. Here Kerb weight does not help as you will appreciate kerb weight includes a number of other things.

Perhaps a visit to a garage would shed some light.

Do you reckon there are any formalities that a dealer will insist on my completing if I were to ask for a brand new engine. Since I am not planning to use it on any vehicle clearly the RTO should be out of the equation. Please advice.
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Old 15th May 2014, 14:56   #4
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Default Re: Sourcing an engine for a Hovercraft

Quote:
Originally Posted by rramesh_68 View Post
Which car engine would be best suited for this requirement in terms of:-
(a) Best weight to power ratio
(b) Track record of good performance on roads
(c) Maintainability
Agreed with the 1.0L K-Series suggestion. Plus, because of its sheer popularity, finding a used engine (from a total loss car) will be easier compared to others.

I don't know much about boats / hovercrafts; however, most motorboats I've seen use motorcycle engines. You might want to factor that in.

Quote:
Can I walk to the car dealer of the car whose engine you might recommend and can I ask him to sell me just the engine or will I have to get from the second hand market
If money isn't an issue, you can get a new one.

However, because it's not the primary business of car makers (to sell engines only), it'll work out way too expensive.

Look up used engine sources like this one (Engine Graveyard - Where old engines go to die..) and this (The Automotive Chor Bazaar Of Mumbai -All in a days work - An Eulogy).
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Old 15th May 2014, 15:20   #5
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Default Re: Sourcing an engine for a Hovercraft

Before looking at candidate engines, does the OP have any calculations on how much vertical and horizontal thrust will be required for different GVW? Those figures will probably yield what could be a realistic engine choice for this application.
On purely a gut feel, I would be Very Surprised if a 1.0 K-Series engine is able to provide sufficient levels of thrust in both directions.
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Old 15th May 2014, 16:11   #6
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Default Re: Sourcing an engine for a Hovercraft

IMO using a 1.3 G13bb MPFI Esteem would be better suited than the tiny 1.0 K10B engine. These are widely available in the seconds market and have been a choice for microlights too. These are rated at around 85BHP and you don't need to redline to get 60BHP out of it.
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Old 15th May 2014, 17:24   #7
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Default Re: Sourcing an engine for a Hovercraft

^ Agree to roy_libran's concern about smaller engine unable to get power required in both the direction.
I am no expert on hovercraft, however from what I make out about hovercraft the downward thrust should is more important since it is required to get the vehicle to 'hover'. A less powerful engine used here means more drag which will negate the horizontal thrust.

I am not sure if a single engine will be able to manage both, in terms of power. However multiple engine means more weight.
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Old 15th May 2014, 21:43   #8
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Default Re: Sourcing an engine for a Hovercraft

Hi Ramesh,

I am going to enter in 4th year and the project I have thought of is also a hovercraft. You have to keep certain things in mind.
1. The biggest one is weight - the lightest , the best.
2. stability - proper weight balancing is a must
3. skirt material - have you decided one?
4. engine - well why dont you try out some calculation with the protable generators/ blowers(might be used for balancing)

With a car engine you might require all sorts of stuff like a starter motor, a battery, timing belt,etc. A better option would be a lawn mover engine. One available in India is BRIGGS & STRATON - 350cc 14hp. There are many other variants available with different capacity and power. We have used this engine in our project (SAE Baja) pics below.
Sourcing an engine for a Hovercraft-img_2349.jpg

Sourcing an engine for a Hovercraft-img_2364.jpg

Sourcing an engine for a Hovercraft-img_2351.jpg
You can see the shaft coming out. It could either be coupled to a CVT, or a direct chain drive to the propeller of the lift fan. This engine is a pull start, hence you save weight on a lot of stuff like battery, starter motor, carb, exhaust etc. Even the exhaust is built in.
The engine was provided to us by Briggs & Straton through SAE Baja at a subsidized price of INR. 45000.
Since it a project, you can also ask for the discounted price. the office of Briggs & Straton is situated in Noida.
hope this helps
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Old 15th May 2014, 21:46   #9
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Default Re: Sourcing an engine for a Hovercraft

Actually gut feel tells me that for a project hovercraft, 50 HP is way overkill. Could you share your calculations, if you don't mind. (Am assuming that your vehicle will have skirts.)

There was a thread on a hovercraft somewhere on this forum. Pls. search.

Regards
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Old 15th May 2014, 21:59   #10
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Default Re: Sourcing an engine for a Hovercraft



This is the prototype of what I am planning to make. I made this for college level competetion. the final one is this : made purely from recycled items
Sourcing an engine for a Hovercraft-20121014_113333_707.jpg
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Old 15th May 2014, 22:11   #11
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Default Re: Sourcing an engine for a Hovercraft

I would suggest 2 stroke Bike engine 100 to 150 cc. Lighter, lesser space occupied, simpler to fabricate in fixing.

Last edited by GTO : 16th May 2014 at 14:56. Reason: Typo
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Old 16th May 2014, 11:43   #12
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Default Re: Sourcing an engine for a Hovercraft

Quote:
Originally Posted by rramesh_68 View Post
I am planning to design a hovercraft sort of a vehicle as a science project. My rough power requirement calculations for the weight I have in mind is about 50 - 60 hp

Which car engine would be best suited for this requirement in terms of:-
(a) Can I walk to the car dealer of the car whose engine you might recommend and can I ask him to sell me just the engine or will I have to get from the second hand market

(b) Since the requirement to drive a propeller, clearly the throttle - rpm control is crucial. If I took the gearbox out (to make the design lighter) what kind of optimal rpm can I expect out of one of these engines (to help me decide the gearing between engine and propeller).

(c) How much would one of these engines with battery and alternator (but without the gearbox) typically weigh?

Any advice would be helpful. Thanks in advance.

Let me share my opinions based on what I did for designing a Howercraft as my Mechanical Engineering final year project. Just remember that with time technology and availability of information has changed greatly in past 13 years so please adjust accordingly!

Design:
1. A round shape plywood sheet around 3.5-4 ft as the base
2. A truck tube served as the skirt
3. 2 blowers for compressed air input
4. Motor with blade for propelling

Two holes were cut on each side of the center on ply and tube to supply air into the tube/skirt. Stick tube & ply with holes overlapping, done the joint at a rubber shop, screwed 2 steel pipes (threaded) that projected onto the ply. Fitted the blowers upside down onto the pipes. Fitted a custom metal stand for the motor and covered it with metal sheet to serve as nozzle cum safety shield (in case blade comes out due to higher rpm). Put a dashboard (aka switchboard) to supply power to blowers & motor at one end and was directly connected to mains with a 3-pin plug at the other.

a) Compare the combined weight of Engine + GB (speed regulator) with that of Electric motor + battery. In my case we did connect it with a power source with wire (not practical but served the purpose of demonstrating a working model).

b) We got an old sewing machine motor that comes with a speed controller pedal and fitted a two-blade heavy duty fan (that we usually have at marriage halls) blade as the propeller. Mind you it was so noisy and blasting such air thrust that at first everybody got scared and later was the number of our HOD!

Quote:
Originally Posted by 4k_jz View Post
I am going to enter in 4th year and the project I have thought of is also a hovercraft.
1. The biggest one is weight - the lightest , the best.
2. stability - proper weight balancing is a must
3. skirt material - have you decided one?
4. engine - well why dont you try out some calculation with the protable generators/ blowers(might be used for balancing)
1. great going.

3. For skirt material we sourced a truck tube and punctured it evenly on inside periphery to let-off the air flow.

4. yes, blowers are good option from my experience but will put a limit in terms of requiring a wire connection. We used two portable blowers placed on opposite side to fill air into tube.

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Old 16th May 2014, 15:43   #13
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Default Re: Sourcing an engine for a Hovercraft

Very interesting to see these science project.

I'm no hovercraft expert by any means, but are the power requirements not a little on the high side? You need surprsing little power for lift, so unless you want to go very fast, not sure how you came up with the 50-60HP.

I just tried a few numbers in this very simple lift calculater:

http://www.hoverhawk.com/lcalc.html

Enjoy, share some pictures of the finished hovercraft!

Jeroen
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Old 16th May 2014, 20:23   #14
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Default Re: Sourcing an engine for a Hovercraft

How big is the hovercraft going to be? And what payload?
If money is not short, How about the 1L ecoboost engine? That should be enough for a single man hovercraft I think. Energy efficiency in a hovercraft is very poor compared to a car. and you'll have to power atleast 2 rotors, one for hover and another for steerage.
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Old 16th May 2014, 21:34   #15
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A big thank you to all those who have come in with sincere advise. I feel before I get anymore and before I lead you all completely off course, I had used the word hovercraft merely to suggest it is something that hovers. Now that my question has brought so many replies and my enthusiasm is growing, let me correct and say what i should have said in the first place. In fact, its more of a hover-bike that I am trying to design.

Therefore questions of how a single engine can deliver thrust in two (perpendicular) directions will become irrelevant. A picture of what I have in mind is Sourcing an engine for a Hovercraft-hoverbike.png.

As per my calculations the engine required will be about 50 - 55 bhp and the drive shaft will be like this Sourcing an engine for a Hovercraft-drivetrain.jpg.

Does this make any of the arguments different?

Still waiting on more advice. Thanks in advance.

Good luck with your project! I like the fact that your new project only uses recycled items. Go green !!

i am not sure a bike engine will deliver the required power.

Last edited by Technocrat : 17th May 2014 at 01:52.
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