[Technique] Réalisations de Maarten JANSSENS

GrahamB a écrit:

Hey Martijn,
Have you weighed the stock R6 frame?

Not yet, but I'll let you know soon!

UPDATE on the moto2 frame:

this total assembly is going to be less then 3 Kg's.

[Vous devez être inscrit et connecté pour voir cette image]

achieving stress/ stiffenss numbers @ 73% of the yield strength (several load cases shown)


[Vous devez être inscrit et connecté pour voir cette image]

Also making modifications to my supermono, starting with the engine...

MJ-Works a écrit:

GrahamB a écrit:

Hey Martijn,
Have you weighed the stock R6 frame?

Not yet, but I'll let you know soon!

For what it is worth. The official  FIM Superstock weight of the R6 chassis
is 10.4 Kg. BO is 6.2 KG.
Just for fun the YZF125r chassis(Made in France) weighs 17Kg(Inc subframe).

Dave Pearce a écrit:

MJ-Works a écrit:

GrahamB a écrit:

Hey Martijn,
Have you weighed the stock R6 frame?

Not yet, but I'll let you know soon!

For what it is worth. The official  FIM Superstock weight of the R6 chassis
is 10.4 Kg. BO is 6.2 KG.
Just for fun the YZF125r chassis(Made in France) weighs 17Kg(Inc subframe).

Yes I have the FIM drawings to

Going to try and make the frame 7 Kg.

Very interesting!

Dave Pearce a écrit:

For what it is worth. The official  FIM Superstock weight of the R6 chassis
is 10.4 Kg. BO is 6.2 KG.
Just for fun the YZF125r chassis(Made in France) weighs 17Kg(Inc subframe).

And an SV650 is 14.2kg, while a Ducati 1098 is 9.6kg

Evidemment, plus le moteur est petit, plus il faut un cadre lourd

Might get confusing here because I'm busy with the supermono at the same time but let's give it a try.

Even tough I tried a lot of different exhaust configurations I'm still not happy. Last one I've used is the two silencer "in-line" setup with a short first pipe, then a silencer diameter 50 mm, a cone that went from 50 to 60 mm and then a second silencer that went from 60 back to 50 mm.

[Vous devez être inscrit et connecté pour voir cette image]

If I take everything behind the first silencer away the engine is much more responsive and feels more powerful BUT too loud  

That is why I'm going to make my own titanium silencer, underneath the engine.

I've got some sketches and I'd like your knowledge about the following options:

[Vous devez être inscrit et connecté pour voir cette image]

What is best for low noise and what is best for power --> which one is the best?

Thanks!

Maarten

In my point of view, the n°2 should be the best, but the ‘machine gun’ holes should start after the Y, in order to less disturb the gases in the curved pipes.

The diameter should be around 35 or 36mm in order to keep the same volume in and out.

May be 3 tubes in your triangular exhaust pipe ???

Anybody else ?

that's exactly what I tought.

Anyone else an other idea?

I'm also voting for n°2: the expansion alone at the split to two tubes shoulld halp break up the pulses, and two tubes give you more surface area to diffuse into the surrounding fibres (I'd be inclined to use 2 x 50mm). The two outlets is also good, since they won't both point at the sound-meter at the same time.
You could also experiment with making one branch longer than the other, to achieve a little bit of phase cancellation, but given the frequencies involved I doubt it will make much difference. Let's just say that if the space available encourages differential lengths, don't fight against it :)

Oui, car un mono de 645 évacue autant de gaz qu'un bicylindre de 1300 dans chaque bouffé. Tu as vu une ligne Ducati ? 70mm à chaque cylindre !
Oui c'est vrai, une 1198 tourne plus vite, mais l'idée c'est d'avoir une expansion, pour que le pulse de gaz soit moins cohérent. C'est tout le principe d'un pot de silencieux, que la gaz se décomprime à travers les trous et le pic de pression se perde dans le volume du pot entier.

Mais enfin c'est une idée...

thanks for the respons mate!

Titanium split:

[Vous devez être inscrit et connecté pour voir cette image]

More will follow.

Working on engine:

[Vous devez être inscrit et connecté pour voir cette image]

grtz

MJ

did some work on rocker arms, not finished yet but getting there

[Vous devez être inscrit et connecté pour voir cette image]

[Vous devez être inscrit et connecté pour voir cette image]

difference in sway with the lathe is just 0.005 mm (this is more accurate) but this works a lot easier.

nice work !

Got the crank within 0.005 mm

[Vous devez être inscrit et connecté pour voir ce lien]

Tommorow I want to balance it.

Question: do I use a balance factor (55%) for balancing this crank (it has a balance shaft) OR do I balance it with only the weight of the piston + pen + translating part of conrod?? I never balanced a crank that has a balance shaft yet...

I think I should ignore the balance shaft because it balances the horizontal weight and not the vertical weight that much.

In my best French:

Pour balancer le vilebrequin je me demande la prochaine question:

Dois-je utiliser un facteur d'équilibre ou pas? C'est la première fois que je fais cela pour un vilebrequin avec un arbre d'équilibrage...

thanks!

Maarten

I think if you search among Frits's posts on the RSA125 (I know, that narrows it to only 165 pages or so... ) you'll find a nice discussion on balancing single cylinder engines.

The quick primer is that you take the lower half of the rod as being part of the crank, the upper part and piston as moving purely in the vertical sense, then resolve the motion into vertical and horizontal parts via sin & cos of crank angle. You see rapidly that with a single, it's simply a choice of vertical or horizontal vibration... but with a balance shaft turning at twice the speed, you can cancel out a lot more of the total vibrational power (sum of squares of the vertical & horizontal velocities).

Calculus is good for the soul

GrahamB a écrit:

I think if you search among Frits's posts on the RSA125 (I know, that narrows it to only 165 pages or so... ) you'll find a nice discussion on balancing single cylinder engines.
The quick primer is that you take the lower half of the rod as being part of the crank, the upper part and piston as moving purely in the vertical sense, then resolve the motion into vertical and horizontal parts via sin & cos of crank angle. You see rapidly that with a single, it's simply a choice of vertical or horizontal vibration... but with a balance shaft turning at twice the speed, you can cancel out a lot more of the total vibrational power (sum of squares of the vertical & horizontal velocities).

I don't expect to find a balance shaft turning at twice the crankshaft speed on a KTM single, Graham. And if I did, I would hope to find two of those shafts instead of just the one, wouldn't I?
Anyway, one balance shaft rotating at the same speed as the crankshaft, but in the opposite direction, will already do a lot of good. Let's forget about the con rod effect for now (assuming its length is infinite), then we can balance the total reciprocating mass by putting 50% counterweight in the crankshaft and the remaining 50% in the balance shaft.
A lot of fuzz is made over measuring this total reciprocating mass, but it's dead easy: see the picture below.
Note that the con rod is completely horizontal and that the gudgeon pin with its bearing, the circlips, the piston rings, are all fitted.
Now if you want a 50% balance factor, replace everything attached to the conrod small end with so much mass (a collection of nuts, for example) that the scales read 50% of their original value. Attach those nuts to the con rod small end and then figure out the amount of material that you have to remove from or add to the crankshaft, so it will remain at rest in any position.
[Vous devez être inscrit et connecté pour voir cette image]

Frits Overmars a écrit:

I don't expect to find a balance shaft turning at twice the crankshaft speed on a KTM single, Graham.

Argh... I'm getting worse and worse lately... I think my brain is shrivelling :-(

Frits Overmars a écrit:

GrahamB a écrit:

I think if you search among Frits's posts on the RSA125 (I know, that narrows it to only 165 pages or so... ) you'll find a nice discussion on balancing single cylinder engines.
The quick primer is that you take the lower half of the rod as being part of the crank, the upper part and piston as moving purely in the vertical sense, then resolve the motion into vertical and horizontal parts via sin & cos of crank angle. You see rapidly that with a single, it's simply a choice of vertical or horizontal vibration... but with a balance shaft turning at twice the speed, you can cancel out a lot more of the total vibrational power (sum of squares of the vertical & horizontal velocities).

I don't expect to find a balance shaft turning at twice the crankshaft speed on a KTM single, Graham. And if I did, I would hope to find two of those shafts instead of just the one, wouldn't I?
Anyway, one balance shaft rotating at the same speed as the crankshaft, but in the opposite direction, will already do a lot of good. Let's forget about the con rod effect for now (assuming its length is infinite), then we can balance the total reciprocating mass by putting 50% counterweight in the crankshaft and the remaining 50% in the balance shaft.
A lot of fuzz is made over measuring this total reciprocating mass, but it's dead easy: see the picture below.
Note that the con rod is completely horizontal and that the gudgeon pin with its bearing, the circlips, the piston rings, are all fitted.
Now if you want a 50% balance factor, replace everything attached to the conrod small end with so much mass (a collection of nuts, for example) that the scales read 50% of their original value. Attach those nuts to the con rod small end and then figure out the amount of material that you have to remove from or add to the crankshaft, so it will remain at rest in any position.
[Vous devez être inscrit et connecté pour voir cette image]

Very clear instructions, thanks!

I'm hoping that it will all pay of.

Maarten

Frits Overmars a écrit:

Let's forget about the con rod effect for now ...

I am eager to learn about this subject Frits

Toop a écrit:

Frits Overmars a écrit:

Let's forget about the con rod effect for now ...

I am eager to learn about this subject Frits

longer conrod gives less translating secundary forces, that is the main benefit!
It also gives less friction between piston and cilinder --> less wear.
there are less tangential forces to so you get a little less power...
Also the secondary acceleration is less and that is a good thing because that is the thing you need a second balance shaft for that runs twice the crank rpm.

That's what I know but I'm sure Frits knows more

Could I make a silencer with an aluminium outer skin or would that just melt? Any toughts on that from anyone here?

I've heard for titanium but just for some plate it's 650 euro's...

kind regards,

Maarten