2 stroke thread (with occasional F1 relevance!)

[gruntguru]

No the idea should be to not need a chute, they´re fine for peace of mind, but this sort of aircraft will never fly to the height needed to deploy a parachute safely in case of a failure, even if it´s rocket launched

Never? What height would that be? >5000 ft?

[Andres125sx]

Well A-125.. that's a bit funny ironic - from someone who enjoyed 'getting air' while 2T powered & sans 'chute..

True and a friend of mine broke his shoulder after that 2T stopped just before a jump

"Never say never".. & as G-G posted, there are now $27 million reasons to disagree with your opinion..

Same for any other, but facts are facts, these personal copters have been tested since 60´s, 70´s as much if my memory serve me well, and they´ve never succed because of a simple reason, not safe enough

I´d love to be wrong, I´d love to be one of the first customers for such an awesome invention, but reality is what it is

[Andres125sx]

No the idea should be to not need a chute, they´re fine for peace of mind, but this sort of aircraft will never fly to the height needed to deploy a parachute safely in case of a failure, even if it´s rocket launched

Never? What height would that be? >5000 ft?

You´ve watched the video right? The needed to allow the chute to be deployed, inflated and some added time to let it brake the copter after the initial drop

And yes, never.... on normal use. Nobody would climb to 1000´AGL just for moving from A to B, why wasting fuel for climbing when it´s not needed at all?

This is not a plane, here height would be a problem not an advantage

[J.A.W.]

A-125.. still too funny..
& an old saying seems apropos to your friend - the crasher..
"A bad workman blames his tools"..

What % of aircraft do provide a 'chute escape option - anyhow?

& most civil aviation authorities certainly do require a minimum 'safe' operating altitude..

[Andres125sx]

What % of aircraft do provide a 'chute escape option - anyhow?

ULM´s for example, and that´s for an aircraft that can glide really well

& most civil aviation authorities certainly do require a minimum 'safe' operating altitude..

Or a maximum, it depend on the type of aircraft.

For example, ULM, paragliders, etc. cannot go over 1200´ (at least here in Spain), wich is the category this sort of aircraft would fit

But they would go closer to the lower limit because of fuel economy reasons

[J.A.W.]

Check this out.. 30,000rpm & its a 2T..

https://www.youtube.com/watch?v=oF8lUPNnwng

[uniflow]

Check this out.. 30,000rpm & its a 2T..

https://www.youtube.com/watch?v=oF8lUPNnwng

Tokoroa, NZ. This engine built by a friend of mine. Some of his engines do 40,000 plus.

[flynfrog]

JAW. Unless your KTM 380 2t is highly tuned, it has less peak power than any of the full face 450s, as current MX 450s make close to 60hp at the rear wheel. A KTM 380 2t is an off-road bike with a much less aggressive engine than an MX bike.

Actually f-f, do please provide the dyno comparison to back your claim..
& it is neither difficult nor 4T expensive to get a KTM 380 to make more power - if you want it..

http://www.rpmmfg.com/BigBoreStrokerKTM410.aspx

old post but you are misquoting me.


But I did post a dyno sheet not sure what you are asking for here. Can you make 60 hp out of a 450 4 stroke yes its expensive can you make 60 hp with a 350 2 stroke yes its expensive.

[J.A.W.]

Current showroom production 450 4T MX bikes are closer to 50 rwhp than 60..

& of course - the softer tuned enduro machines are making less.

Fact is though F-F, it is less expensive to power tune a (comparable) 2T than a 4T,
since all the 4T cam/poppet valve gear complexity makes it inevitably so..

[flynfrog]

Current showroom production 450 4T MX bikes are closer to 50 rwhp than 60..

& of course - the softer tuned enduro machines are making less.

Fact is though F-F, it is less expensive to power tune a (comparable) 2T than a 4T,
since all the 4T cam/poppet valve gear complexity makes it inevitably so..

I dont recall I have said otherwise at any point neither is that cheap to get 60hp

[J.A.W.]

2T is - nevertheless - significantly less expensive to tune & run - at comparatively higher levels of specific output..

[uniflow]

JAW. Unless your KTM 380 2t is highly tuned, it has less peak power than any of the full face 450s, as current MX 450s make close to 60hp at the rear wheel. A KTM 380 2t is an off-road bike with a much less aggressive engine than an MX bike.

Actually f-f, do please provide the dyno comparison to back your claim..
& it is neither difficult nor 4T expensive to get a KTM 380 to make more power - if you want it..

http://www.rpmmfg.com/BigBoreStrokerKTM410.aspx

old post but you are misquoting me.


But I did post a dyno sheet not sure what you are asking for here. Can you make 60 hp out of a 450 4 stroke yes its expensive can you make 60 hp with a 350 2 stroke yes its expensive.

No it's not, just some port and exhaust mods. My 1973 Kawasaki makes 50 crankshaft HP, and it's more than 40 years old ( air cooled too).

[Abarth]

The fruits of specific power are low hanging in the 2 stroke world.
It gets a bit more difficult to do it with good efficiency and acceptable emissions, but the technology is here.

With forced induction à la actual F1 (with a MGU-H allowing for a pretty wide range of boost mapping and harvesting the kinetic energy) it would be a very interesting field of research.

I'd go for a DI 2 stroke engine with classic Schnürle loop scavenging, and sump lubrication. Of course the MGU-H would allow for this, as no crancase pre compression would be needed.

[gruntguru]

Probably wouldn't need crankcase scavenging either - with an electric turbocharger.

[FW17]

With the exhaust pulse of a 2 stroke the energy recovery will be phenomenal, may be up to 50%