ESE's works engine tuner

[SwePatrick]

images from the caster!

Nice..
Is it lost wax/lost foam casting?

[Muhr]

Nice..
Is it lost wax/lost foam casting?

Yes, you can say that.

"printed PMMA model on a 3D printer system. Then the model is embedded into plaster and subsequently the model is burned out. Finally vacuum is applied to to the plaster mold and liquid metal is poured into the resulting cavity."

[SwePatrick]

Yes, you can say that.

"printed PMMA model on a 3D printer system. Then the model is embedded into plaster and subsequently the model is burned out. Finally vacuum is applied to to the plaster mold and liquid metal is poured into the resulting cavity."

Depending on skills in moldmaking lostfoam/wax can be very very precise castings.

[Haufen]

The roof angle of 25° (?)(I never measured it!) was completely STD ROTAX, I never changed it.
What I did first was enlarging the auxiliary ports, with good results.
But they were too high already.
When I could cast my own cylinders I made them lower and wider
And of course the 'ski jump' was introduced immediately after good results with other engines.
I saw that when a cylinder seized the divider between main and auxiliary frequently cracked.
So I tried to make an 'indestructible' cylinder, by making this divider bigger and longer.
With a nice round corner around it.
I lengthened the divider until almost the exhaust flange.
As I had seen on a Krauser 80cc cylinder.
The result was a very good central exhaust duct flow.
And also a really good separately measured auxiliary duct flow.
But the total exhaust flow diminished, and the engine did not rev.
By gradually shortening the divider wall I got over-rev and power back.
Until the best result was reached by coming back to original ROTAX dimensions.
I was very displeased, away went my dream of an 'indestructible' cylinder......
A pity, but I had to live with it.
It took years of work to reach the best auxiliary duct and ports dimensions.
The main port was made a little bit 'squarer' and narrower around 2001, and the auxiliaries widened to the inside.
The exhaust main port was unradiused until I tried a new exhaust pipe which gave very good low and midrange power,
but wouldn't rev.
Making a radius made it rev, but we lost most of the gained mid- and low range.
We decided to leave it like that....as it was good for the piston ring.
Later we started to raise the exhaust port floor, it looked quite good, but then I retired.
The goal was to reach a point at which the A-ports could have been made still wider.
I don't know if this was ever tried later.
I heard about a 'Honda' type exhaust duct being tried, it lost 1,5HP.....

Thanks for sharing, Jan. Would you be interested in playing around with a simulation model of the RSA to see if and where things could have been improved even further in the past? In my model, which is based on an APF cylinder from the 2011 season and a different inlet (as I only have the cylinder and not the whole engine), I broke into the 60ies some time ago (6+ hp over baseline calibration which I set to 54 hp. sim data predicted same or slightly better detonation behaviour (TuBmax)).

-------------------------

By the way, I'd be willing to trade detailed information about the 2011 cylinder in exchange for the same information of the last version of Jan's work (that would be 2007 correct?). Anyone interested please drop me a line.

Would be interesting to see if and what had been changed after Jan retired.

[wobbly]

There is nothing secret about the RSA125 cylinder, nor most of the engine dimensions,except for fine detail about the 3D ignition curve, the PV curve and the PWM operation of the
PJ.
Here is a RSA125 pack that has been added to and changed by several people over a long period.
This just adds to everyones data knolwedge on here so how about you publish what you have Haufen.
Its easy to go over 60 Hp with the Aprilia sim , just change the Ex duct to the guidelines I have published and adapt the pipe header to suit.

Bugger - I cant upload a .pack file on here, can Admin fix this please.

[Flettner]

ok, lost wax casting in plaster?
One of the reasons sand is still used in casting items with lots of core surface area is it's ability to 'breath' , let gas escape. Often even drilling holes into the core through the core prints (lugs that support the core in place) to facilitate easy gas exit. Plaster?
Also shrinkage, aluminium will shrink as it solidifies (obviously) but this means as the aluminium solidifies it will need extra material supplied to the cavity, or the metal will not fill the cavity accurately or worse still cavities will appear within the the metal itself, holes. What is required is a 'feeder' of molten metal above this solidifying cavity.
You really want what is termed a freeze line running up your casting as it cools, bottom first, with the 'feeder' solidifying last having feed all casting first.
This will need to be accounted for in your wax pattern. How much does the wax shrink? how does that affect accuracy? what wax used? bee wax has least shrinkage.
Seems a messy process, what not use your 3D model to print actual patterns and core boxes and cast in CO2 sand?

[husaberg]

ok, lost wax casting in plaster?
One of the reasons sand is still used in casting items with lots of core surface area is it's ability to 'breath' , let gas escape. Often even drilling holes into the core through the core prints (lugs that support the core in place) to facilitate easy gas exit. Plaster?
Also shrinkage, aluminium will shrink as it solidifies (obviously) but this means as the aluminium solidifies it will need extra material supplied to the cavity, or the metal will not fill the cavity accurately or worse still cavities will appear within the the metal itself, holes. What is required is a 'feeder' of molten metal above this solidifying cavity.
You really want what is termed a freeze line running up your casting as it cools, bottom first, with the 'feeder' solidifying last having feed all casting first.
This will need to be accounted for in your wax pattern. How much does the wax shrink? how does that affect accuracy? what wax used? bee wax has least shrinkage.
Seems a messy process, what not use your 3D model to print actual patterns and core boxes and cast in CO2 sand?

One thing in plaster and wax's Favor Flet, is that it allows very fine detail and given that the plaster is also an excellent insulator, maybe it should actually have less problems as it might not cool as quick as a sand mould does. I haven't tried it of course.... But it seems plausible.

[Flettner]

with my copy cast F9 cylinder head, in CO2 sand, it's even got Made in Japan copied in fine detail, done right sand has excellent finnish.

[husaberg]

with my copy cast F9 cylinder head, in CO2 sand, it's even got Made in Japan copied in fine detail, done right sand has excellent finnish.

Is Japan the Maori word for Waikato

[Niels Abildgaard]

Hi Fritz. We finally make (paramotor) engines with opposite exhaust, would intensively test.



The first impression works very well, though we have not correct assumptions how make best possible geometry.

Looks interesting and a lot of air resistance.
Has Turbocharging been considered?
The job of an aircraft engine is to deliverl longtime,reliable power for less mass , air resistance and fuel.
Most people here tries to maximise power from a single 125 ccm cylinder.
Your engine as a V2 it will be much kinder to propeller and aircraft and turbocharging will minimize noise and infrared signature.
Fast throttle responce is not so important as on a kart or bike.

[Muhr]

ok, lost wax casting in plaster?
One of the reasons sand is still used in casting items with lots of core surface area is it's ability to 'breath' , let gas escape. Often even drilling holes into the core through the core prints (lugs that support the core in place) to facilitate easy gas exit. Plaster?
Also shrinkage, aluminium will shrink as it solidifies (obviously) but this means as the aluminium solidifies it will need extra material supplied to the cavity, or the metal will not fill the cavity accurately or worse still cavities will appear within the the metal itself, holes. What is required is a 'feeder' of molten metal above this solidifying cavity.
You really want what is termed a freeze line running up your casting as it cools, bottom first, with the 'feeder' solidifying last having feed all casting first.
This will need to be accounted for in your wax pattern. How much does the wax shrink? how does that affect accuracy? what wax used? bee wax has least shrinkage.
Seems a messy process, what not use your 3D model to print actual patterns and core boxes and cast in CO2 sand?

My knowledge of how this process is relative to others is quite limited. You can certainly find more info here https://www.formkon.com/prototypes-aluminium-magnesium/

[jbiplane]

Looks interesting and a lot of air resistance.
Has Turbocharging been considered?
The job of an aircraft engine is to deliverl longtime,reliable power for less mass , air resistance and fuel.
Most people here tries to maximise power from a single 125 ccm cylinder.
Your engine as a V2 it will be much kinder to propeller and aircraft and turbocharging will minimize noise and infrared signature.
Fast throttle responce is not so important as on a kart or bike.

Hi Niels

This is 294cc boxer with 2 cylinders 66bore 43stroke 10,5 compression ratio. It used for paramotoring with direct propeller
drive. We need max power on relatively slow rpm 6000...7000.
The set as on picture weight 9.5 kg, installed chinese copy of Mikuni 32mm. We got from this engine 21hp at 6800 rpm.
Hope with this "opposite" resonator will get a bit more.
If we get 27 then we will be completely happy. As nexts step will install fuel injection.
How install lighweight turbocharger on this with common crancase and shnurle transfers?

[Niels Abildgaard]

Hi Niels

This is 294cc boxer with 2 cylinders 66bore 43stroke 10,5 compression ratio. It used for paramotoring with direct propeller
drive. We need max power on relatively slow rpm 6000...7000.
The set as on picture weight 9.5 kg, installed chinese copy of Mikuni 32mm. We got from this engine 21hp at 6800 rpm.
Hope with this "opposite" resonator will get a bit more.
If we get 27 then we will be completely happy. As nexts step will install fuel injection.
How install lighweight turbocharger on this with common crancase and shnurle transfers?

Hello

I tried to delete my post when I discovered that it was a paramotor engine and not for a drone,but You were to fast answering.
What is prop diameter and with 28 kg per litre/5 bar mean effective pressure You are doing very fine I think.
The turbo shall probably be blowing into a volume before crankcase with reed valves.Without FI it will be very dangerous for the pilot.

[flyonly]

If a bike has a counterbalance shaft and you are only going to use it for racing so idling isn’t going to be an issue is it worth removing? 50cc bike so I am guessing every little bit helps?


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[husaberg]

If a bike has a counterbalance shaft and you are only going to use it for racing so idling isn’t going to be an issue is it worth removing? 50cc bike so I am guessing every little bit helps?


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Out of balance actually engines cost HP..
The rider finds it harder to maintain concentration when engines vibrate
Not only that but the chassis needs to be beefier.
Also less parts of the bike try to escape of it when you leave it in place.
Another advantage is that they lessen the gyro force from the crankshaft clearly important in a big bore bike.
The crankcases are generally designed around the engine having a balance shaft.