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Author Topic: 3mm venturi testing  (Read 4725 times)

Offline Mike Greb

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3mm venturi testing
« on: October 24, 2014, 05:45:20 PM »
Has anybody been testing with the 3mm venturi yet?   So far the best airspeed I have gotten on as SV model is with a wilk yougov prop cut down to about 5.65  Have been getting about a 45 lap range max.

Offline Steve Wilk

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Re: 3mm venturi testing
« Reply #1 on: October 25, 2014, 10:49:48 AM »
Here is a posting the Vova Makarenko made on facebook.

Full report about 3 mm venturi.
Me and my pitman Fulitka Vova have used 3mm venturi during last competition.
First of all we removed piston induction on the engine. Fulitka made new piston for this. After testing this engine with standart venturi we lost 0,4-0,5 sec speed. Then we tested this engine with 3mm venturi. We could not fly even one tank to the end, engine was too hot. After many tests we made our prop 10 mm shorter. (146 instead of 156) after this we had at last normal sound of engine and 55 laps. Speed was 18.4-18.6
We had 3,31 in first heat. Difficult to make right warm up. First 15 laps engine was too cold and speed was around 22 sec. After warming the model was running 18.5 we made only one landing.
In the second heat we made 3,19
Good warm up, start and pitstop with first flick. After 40 laps engine was little too hot, but speed changed not much (18.9-19)
Third heat was not good for us. During warming up we made the engine to hot and it was overheated on 30rd lap.
Fourth heat was not bad except engine was starting wrong rotation side on the start. We had to wait around 6 seconds till it stops and started again. This time engine started well and we did 3,25
3,19 was enough to get in the final. We did only three landings and 6.39 ( first 100 laps we did with 3,17).
I hope this information will be helpful for everybody! Good luck in next season!

Offline Steve Wilk

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Re: 3mm venturi testing
« Reply #2 on: October 25, 2014, 10:53:35 AM »
The weather has turned to cold to do any testing in Minnesota.  We are hoping to make it Florida soon and do some testing. 

Offline Steve Wilk

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Re: 3mm venturi testing
« Reply #3 on: November 11, 2014, 04:57:10 PM »
Here are some notes on 3mm Venturi from Victor Yugov

Letter about Venturi from Victor Yugov

In the first half of September we had a great test of 3mm venturi.
Back in Poland, at the World Cup, we decided to run the last qualifying competition
Russian Cup with 3mm venturi. Competitors had three weeks to prepare.
Then we held a competition. Earlier I sent you video and results.

Now for the details:
-Each Team used its own fuel from this season. Experiments were mainly with propellers and venturi.
- Only three teams can get there settings to get 50 laps per tank (Dozidaev, Andreev, Shabashov).  Speed in this case was 17.8-18.5.
Even Cherednychenko could not achieve more than 49 laps.
- Many teams experienced problem when engine starts up in the opposite direction. (CW instead of CCW)
- The teams of the second level were slow.  Speed was around - 19 to 20 seconds.
- Everyone had problems with growth of carbon, carbon deposits.
- The sound of the engine is often not informative; it does not allow you to understand what engine wants. Nobody liked those races. It was not interesting. No satisfaction. More problems than it was with big venturi. This was especially for the second-tier teams.
Requirements to the motor, to its conditions have increased in comparison with the big venturi.

Later we had a test "standard fuel" of your prescription:
10% Shell Racing Advance M30
30% ether
60% of kerosene for lamp
1.2% DII2
Performance were good, the same as yours, and the same problem - the growth of carbon.

In early October, we held the Moscow competition (7 teams) with 3.5mm venturi.
Everyone loved it. The motors were working well.  Our leaders reached speed of17.2s on easy setting with 40 laps. In the finals everyone were flying for 40 laps at a speed of 17.8-17.4 on easy setting. There were no problems for anybody.

After the competition we got together and discussed our impressions from engines working on 3.5mm venturi.

Overall opinion was: ďIt is what we need for F2CĒ. Everything became way simpler. At the same time the speed was quite satisfactory, we donít need more, we donít need less.  At those settings and speeds both competitors and judges all have time to see and react.

Later we had a test on the venturi 3.5 with the "standard fuel."
Motor worked fine too - speed reached 17.0 at 40 laps. No problems, except for increases of carbon. But it was due to old oil Shell and lack Motul 800.

We came to the following thoughts:
- Official standard fuel is not acceptable neither for the competitors nor for the organizers as strongly complicate the competition organizing process, and perhaps now it is not needed.
- Motor with reduced air consumption (with venturi 3 - 3.5mm) becomes much less sensitive to the fuel. As a consequence there is no need to search for and use of toxic, dangerous, exotic fuel additives.

Perhaps now there will be not need to take kerosene and etherwith you on the plane.
Organizers can provide kerosene and ether at the side by requested by competitors.
The small amount of oil and DII is always possible to take with you in the baggage on the plane.

Looks like there's a big difference between the fuel combustion (burning) in the engine with 3mm venturi verses 3.5mm. With 3mm venturi on the rich setting for40 laps combustion (burning) is bad. For this reason, people are already looking for oxygenated fuel additives. This will complicate the F2C.

With 3.5mm venturi combustion (burning) is "right." Therefore, it may not need additives except DII in the fuel.

Here in Moscow weather has ended. We ask you to test the Venturi 3.5mm.

Victor Yugov

Offline Steve Wilk

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Re: 3mm venturi testing
« Reply #4 on: November 24, 2014, 05:25:44 PM »
The official minutes of the April CIAM meeting clearly state that 0.6mm sub piston induction ONLY is permitted. This was unanimously approved by all delegates.
There is NO need to change all the pistons on your existing engines. You can carry on  and use them in the further experimental work that is required to bring the noise level down to the FAI 96db @ 3 meteres limit!
Best regards,