a lot of questions!!

[Anonymous]

Good morning to everybody!!! 😀

I’m working very hard assembling my new f1c, next time I’ll show you the photoes.

But now I’ve got a lot of questions about the engine: I have 5 engines new, Rossi 15 glow engine. They are old ( 1996 ) but are new and when I made the running test where very fast: 29.000 rpm with a good propeller ( 210 mm of diameter X 105 mm ).

I think to have a good speed, having a good altitude in 5 seconds…..but the geared engines are so faster then traditionals engines?
I don’t know how is the difference: a few meters or double altitude?

2nd question: what type of gearbox is better? the epycicloidal system ( like Verbistky or Nelson ) or another type like graupner?

3rd question: anybody know where can I buy Seelig timer for f1c in Italy? anybody has a link for me?

Thaks a lot for your help-desk, I come to work ( on my wings!! )

Ciao

Stefano

[Anonymous]

Hi Stefano

Yes you have asked some good questions, but first, are you correct on the propeller size you have quoted as giving good rpm on your Rossi? The reason for asking is that they perform best on a 7″ x 3.5″ (180 x 90) and the size you mention is equal to an 8.25″ x 4″ 😕 If you are correct then you have an exceptional engine.

The experts will come in here but from what I have observed the geared engine gains slightly more altitude in 5 seconds than a non-gear engine. I would not advise you to try and modify your Rossi to fit such a unit, the crankcase may not be strong enough.

As for gear boxes, the Verbitski/Nelson planitary gears system has proven to be efficient and reliable; the Gruapner unit I have no knowledge of and if it worked people would be using it but they appear not to.

As for Seelig timers try ebay.

Ployd in OZ

[JLorbiecki]

After flying at the world champs, it was readily seen that the geared motors had a definate advantage as far as altitude. John’s models got up well, but there was anywhere from 50-100 feet difference between him and the best geared models.

I am a true believer that you need to be consistant in whatever you fly to be truly competitive. If you are flying a direct drive model, have the pattern dead straight, have a good transition (bunt), and you can be competitive. You have to make the first 7 maxes and most modern F1C models should be able to do that direct drive.

But, if it is calm and you are in a 10 minute round, rarely will the direct drive model be competitive with an excellent running and trimmed geared model.

As someone beginning in F1C, I guess i would recommend a direct drive model. Learn all you can with it, get some experince in competition, and then get all the tricks.

If you do go gears, I think the pecking order would be a Hummer and then the Verbtsky. There are also a few others that we saw at the WC. One version was a 3.8:1 gear (verses the normal 4:1).

I also have never seen a Rossi that is competitive with either the Nelson or Verbitsky. I am afraid that technology has passed it by. One main area is the big cranks that the two have, plus improved porting and piston/liner technology. best prop I ever found for the Rossi was the older AAU unit which was a 7 x 2.5….

Good luck!!

[Anonymous]

thanks for your answers.

Esactly my rossi comes on 28700 rpm with my propeller. The propeller is carbon fiber self made, and is a mono-wing ( I don’t know the english esactly word! )
I am sure that it is a 210mm x 105mm: I tryed to run it on electric test engine and I have misured the absorbed current: empiric system to discover the power, around the 950 Watts. May be correct.

The last version of Rossi ( black head edition ) has the cilinder with five holes+exaust, the old rossi has 3 holes + exaust, is an ABC and has the ventury for immission largest ( 9mm the last version, 7,5mm the old ).

This last version was not produced in series: my engines are prototype and after mine, Mr Rossi did not produced anymore.

I think it is not possible to put on a gearbox on my engines: the crankshaft is not enough strong, but now I’m trying to made a new version of propeller: I’m sure that I can reduce the rpm with a more strong propeller to be faster on flying ( not like a geared engine, but good!)

When I’ll have a few minutes, i’ll made photoes of my new wings and I’ll show you.

Ciao

Stefano

[Anonymous]

Hi Stefano

You English is better than my Italian. So, you are using what we would call a singe blade propeller which from memory can be larger in diameter and pitch that a conventional 2 bladed propeller and it als looks like you are using a Rossi speed engine.

I would not waste my time testing the propellers on an electric test rig, it is best to fly it on a model then you will get a better indication if it is effective or not. My guess is that you will need to come down on pitch for the propeller to be useful. That is the testing method I and many others have used.

Ployd in OZ

[Anonymous]

new question: I would like to know the weight of your wings.

I’ve terminated today my new wings, they are 36,5 dm2 ad 220 Gr of weight.

Do you think they are too heavy?

Thanks a lot!

Ciao

Lake

[JLorbiecki]

I just looked at my paperwork from the WC and the wings weighed 219, 220, and 221 grams. So, you are right in the ballpark!!

[Author]

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