paramotor

[bren86]

Hi guys as i have seen on this page there are a lot of very intelligent people so i got questions for you. I work with a company that build, teach and fly paramotors in Australia and have been for about 15 years now. We have got a couple of world records under your belt and are always looking for more. The one we want next is altitude. So the highest you could possibly fly. At the moment it is at 28,000 feet. So we have done a little testing with the stock motors (Vittorazi moster plus 185cc 2 stroke 25hp and bailey v5 180cc 4 stroke 22hp) and as Australia has a hight restrictions of 10,000 feet with out all the right approvals thats what we are restricted to at the moment. So we understand oxygen deficiency and atmospheric air pressure and temperature is where the problem starts. We are building a turbocharged 4 stroke 180cc and only running low boost just for atmospheric compensation. But with a fixed propeller we really wouldn't be gaining to much. My goal is a small 30-40hp turbo prop but thats not that easy to come by.

[mitch]

Hi Bren86,

I was looking at the specs on that bailey v5 engine, I think it's pretty cool that you guys have turbo'd it. Did you convert it to electronic fuel injection, or modify the carb to deal with the boost? I also noticed that the engine is air cooled, how well does the engine deal with the extra heat produced from the extra power from the turbo? I did see that the bailey engine does have variable ignition advance, which is pretty cool.
This is a very cool project, as I was interested in trying to convert an old lawn mower engine to EFI forced induction for a while.

Also, just a thought, what about a water cooled 4 stroke dirt bike engine? The water cooling would allow for more power production with boost, and many modern 250cc dirt bike engines have 2 cam 4 valve heads that also offer more power options than the bailey's single cam, 2 valve head. Just some thoughts!

[gidge348]

Hi, were you thinking of a variable pitch on the turbo prop? If you are looking for a 30-40hp turbo prop a suggestion may be John (Racket's) system where he used a pulse jet as the gas generator for a turbo prop www.youtube.com/watch?v=uqMn0A2aUdo

But rather than a pulse jet you could use something like a JFS100 as the gas generator. The whole set up would be maybe 40kgs??? not sure of weight limitations but probably make 80-100hp with heaps of torque??

Cheers
Ian...

[racket]

Maybe use an "off the shelf" 40 lb thrust RC engine as a gas producer and build your own freepower/gearbox .

What sort of turbo are you using for the current IC engine experiments??

I guess you're already looking at very high boost , at 28,000 ft you'll be at minus 40 C and air pressure and <5 psia so lotsa boost to keep sea level power .

Your 30-40 hp turboprop will be loosing lotsa HP at 28,000 , you might need more initial HP .

Cheers
John

[bren86]

Ok another thing is weight remembering that you must take off with it on your back and run. The turbo is a RHB31/VZ21 like the ones from Ecotrons use and we have modified it and removed the flanges and made slip in joints to save on weight also we have been talking to them about fuel injection atm as the Bailey top end is based on the gy6 scooter engine and top end parts are plentiful like water cooled barrels, 220cc  big bore kit, 4 valve heads and high flow oil pumps. Water cooling would be great but weight with radiator pumps hoses and coolant. As for boost it would only be low like 2psi at sea level.  A  variable pitch propeller Would be the game changer and i have tried to make some but are just not going to work. We have been think of using  multiple fuels that are oxygen in riched as we need. 

[enginewhisperer]

interesting project!

I have a couple of RHB31 turbos I've been thinking of using on similar capacity engines.
I also have a 300cc quad bike engine (and can get more of them) which are based on a GY6 but water cooled and don't have an internal gearbox.

A while ago I picked up a couple of EFI throttle bodies from late model small motorbikes which would be very easy to use for conversions. They have the TPS, MAP sensor and injector built in which makes things nice and simple.

[bren86]

Is that the Linhai DongFang 300cc. How much

[mitch]

So will you turn up the compressor speed/ boost at higher elevations?

[bren86]

Was thinking at keeping at a constant boost level as we dont want more power as that would over speed the propeller. Boost would stay the same just wheel speed will increase to maintain the constant boost

[enginewhisperer]

Jan 12, 2017 22:45:34 GMT -5 bren86 said:

Is that the Linhai DongFang 300cc. How much

yep that'd be the one.

A friend has a few of them from brand new quad bikes that were converted to electric.

I think he wanted a few hundred dollars each. They have the radiator, electrics, etc.

[racket]

Have you done the corrected flow calcs for >25,000 ft with that turbo ??

It might work at sea level but the volumes needing to be "processed" at altitude might cause problems .

Cheers
John

[bren86]

No John i wouldn't even know where to start.
Thought a turbine would be more linear in power at high altitude just consume more fuel.

[racket]

Because your "vehicle" speeds are very low you won't have the ram effects normally associated with high altitude, high speed aircraft which aid in lowering the altitude "losses" .

A shaft horsepower turbine starts losing power as the mass flow reduces with altitude density , there are some benefits from the colder air compressing more easily , but you'd probably find you'd need 60 sea level HP to get your 20 plus HP at 30,000 ft .

Then theres the matter of prop efficiency and getting it to "bite" the thin air .....................lotsa research required for a project like this .

As regards the turbocharging and "corrected flows" , its not that complicated if you've got some basic numbers regarding the naturally aspirated engines mass flow .

Cheers
John

[bren86]

So we ended up just getting a rotary drone engine. 300cc 8000rpm 60hp supercharged 20kg. That is with water pump oil pump redrive engine mounts. Next step is efi and turbo.

[Johansson]

Probably a wise choice, good luck with the project!