V6 90cc

[lechataignier]

Hello,
I mentioned it in my presentation as a new member, here it is in more details.
The design is totally personal but uses solutions from WTengines, especially for the crankshaft.
I designed this engine under SW to equip a future Caudron CR714.
The advantage of this plane is that its engine is air cooled, so there is a large air intake in the cowling. The V is at 60°. One thing I regret is not to have tried to respect the ratios bore, stroke and length of connecting rod. 12 cylinders was too much for me.
The plane in question :

and its engine :

And my very freely inspired version :

I read the post on carburetion of multi-cylinders. I'm confronted to this problem. For the intake pipe, I was inspired by the Merlin V12, but it only works well at idle.
As soon as I opened the throttle a bit, it was completely messed up and it was obvious that the cylinders were not all seeing the same amount of fuel.
I really wanted to avoid multiplying the number of carburetors for the ease of adjustment once the engine was under the hood. But the only solution I found that works properly is with two carburetors that spit into an empty box to distribute to all cylinders.
It's not as nice and still needs some finishing touches.
The working intake:

Tests that don't work :

For this last test, the carbs were clearly much too big.

Bruno

 

[lechataignier]

Some parts. I had started to make 2 of them. The second one is much less advanced because I wanted to make a different crankshaft for it. Finally, the second one may become a 4 or 6 cylinder flathead.

 

[lechataignier]

Now I'm waiting for the right moment to do a test flight with an easy plane that doesn't risk much.
The plane has a 2.50m wingspan.

Bruno

 

[petertha]

Beautiful work!
- is lubrication entirely pre-mix oil in nitromethane fuel?
- how are you powering the 6 glow plugs? The one video kind of looks like battery cells
- on your new crankshaft, are they split on centerline & captive within a bearing or something like that?

 

[lechataignier]

Beau travail!
- la lubrification est-elle entièrement constituée d'un mélange d'huile de minerai et de carburant nitrométhane ?
- comment alimentes-tu les 6 bougies de préchauffage ? Le type de vidéo ressemble à des cellules de batterie
- sur votre nouveau vilebrequin, sont-ils divisés sur l'axe central et captifs dans un roulement ou quelque chose comme ça ?

View attachment 142747

Thanks,
Yes, the fuel is methanol with 18% oil and the lubrication of the lower engine is only due to the leaks in the rings. The engine has already burned a lot of fuel for my carburetor tests and the connecting rods did not take any clearance.
For the glow plugs, I simply have a battery of 5 nimh cells in parallel. In the plane I have a servo and 2 switches :

The 3 pieces of crankshaft are well assembled at the level of the intermediate bearings (between each cylinder) mounted tightly. This is the solution adopted byWTengines.

Bruno

 

[e.picler]

Congratulations Bruno!
Very nice building.

Edi

 

[awake]

Marvelous and impressive!

 

[lechataignier]

Hi,
One year after the first start-up, the first flight took place:



Finally there are 3 small SH (Just engines) carburettors with Y-pieces to feed each 2 opposite cylinders.
However, not all cylinders were working in flight. The heating of the spark plugs is not terrible with 1 Nimh battery (5 cells in parallel) of 1.2V, there are too many losses in the wires which are a little long.
The carburettor setting is still a bit rough.
Apart from that the flight of the plane is rather easy with a weight of 11.8kg.

 

[oldCB]

Do you fly real planes or ultralight?

 

[lechataignier]

Do you fly real planes or ultralight?

No, only scale models, for over 30 years.
I had a few flying lessons on a Cessna, but that was a long time ago, before I started a small family...

 

[awake]

Again, very impressive. I can only imagine what a joy it is to see something that you made from start to finish successfully fly!

 

[petertha]

Congratulations! That is a beautiful engine. What is the maH capacity of your NIMH cells? Are you using 4-stroke plugs or 2-stroke plugs?
I cannot yet tell if I will be successful but for my 5-cyl radial until spring when the snow melts, but I bought 5 glow drivers from AliExpress & assembled them into a switch box like so. Intended for bench running but same principle. They are regulated voltage output & nice thing is drive them with a single common LIPO battery so dont have to worry about voltage mismatch what plug requires & easily handles amp duty. So far so good on the test. I also soldered up 5x2200maH cells in parallel just to bench test. They do work but as you say, have to pay attention to wire & connector losses.

 

[lechataignier]

Thank you for your comments!
I use OS "F". The battery is a 5 cell Nimh 3300mAh in parallel. But there are almost 0.3V losses in the wires and switches and the voltage drops too fast during use.
I'm quite interested with this glow driver, but it's not the same price:
Microsens Electronics - Glow9C
A priori, it detects when a glow plug is flooded, to send a little more intensity.
Too bad Rcexl doesn't make a glow driver for multi-cylinders:
https://fr.aliexpress.com/item/4000...!sea!FR!3160791205&curPageLogUid=FKQMoq1zAoaX

 

[josodl1953]

Maybe you should take a look at the site of Rainbowtronic in Germany Start .
As far as I know they have glow drivers for 5 and 7 cylinder engines but maybe they can provide you with a 6-cylinder version.

Jos

 

[lechataignier]

Maybe you should take a look at the site of Rainbowtronic in Germany Start .
As far as I know they have glow drivers for 5 and 7 cylinder engines but maybe they can provide you with a 6-cylinder version.

Jos

Thanks, it looks interesting.
I just sent them an email.

 

[vagpas]

The photo with the engine sitting on top of music scores sheets is majestic!