why there aren't any 4 strokes gas engines?

[aerowiz]

So please tell me if i can get a 4 stroke twin that puts out as much power as either of my 3w170's, weighs around the same weight and is as quiet.

I would be interested to know what prop that engine swings for an rpm and after 10 hours of use exactly what maintenance was carried out.

I only ask these questions because after having considerable experience with an earlier moki 4 stroke, Im not sure i would feel safe with being towed behind a moki powered anything.

[ferincr]

[

So please tell me if i can get a 4 stroke twin that puts out as much power as either of my 3w170's, weighs around the same weight and is as quiet

I guess there will always be a trade off. We see that in any other aspect of life. Cars, gas vs. diesel vs. electric.
Even without going that far electric models vs gas models
There is one that seems to fit each of us better than the others...

[Bob Morrow]

Just a few thoughts from my viewpoint about the use of 4-stroke engines.......

I have used 4-stroke engines in a variety of models for many years, very successfully. I started changing over to electric models though about 4 years ago and have since sold all of my model engines.

From my experience with them for many years and also recent developments with them I can say they do work very well and are not difficult to run and maintain. They do have some very distinct disadvantages though that others have mentioned possibly:

The cost of the 4-stroke is generally higher than similar sized 2-stroke glow or gas engines and there is also somewhat of a power difference between them and similar sized 2-stroke ebgines.

In many of the various aerotow events I have been to the workhorse for the tugs has been the gas engines, They have several advantages over the use of other engines, probably the greatest being the ease of use and the costs involved.

Once set up properly the gas engines seem to be very reliable and using a gas mixture is relatively inexpensive as compared to the glow fuel needed for the 4-stroke engines in general (this becomes more of an issue when you look at the running time for the tugs and realize they burn through gallons of fuel per day doing the tow duty......typical 4-stroke fuel that I have found to be very reliable is commonly a helicopter blend that is between 15% to 30% nitromethane and higher oil content costing about $25 to $35 per gallon, which adds up very quickly). I do know there are also many of the 4-strokes that are now set to use gas rather than glow fuel, making the fuel cost much less of an issue.

There are many high end 4-stroke engines now available for use with larger aircraft. One of the companies importing these as well as various large aircraft is Vogelsang Aeroscale:

http://www.team-aeroscale.com/

They have Moki as well as other 4-strokes in there catalog. I also should mention they are an importer of the Tomahawk Wilga that is beautiful along with a couple other scale prop models that would be good as tugs.

O.S. Evolution, and Saito are other excellent manufacturers of 4-stroke engines to be looked at. These are reliable engines and work very well. I have personally used both the O.S. and Saito 4-stroke glow engines for many years with very good success (single and double cylinder). The have a range of engines in single to muli cylinder that are inline, opposed, as well as radial.

For the Saito and Evolution look at Horizon Hobby:

www.horizonhobby.com

And for the O.S. look at O.S. Engines:

http://www.osengines.com/

One of the final thoughts I would suggest is to be aware of the complexity of the parts and construction of the 4-stroke engines as compared to others. Many more parts that are required to function well and over time will need adjustments that to some extent are more demanding than keeping the 2-strokes up and running. This is also an issue as far as repairs and parts counts for the engines if anything is damaged or fails.

What would I do myself ?

To answer this I would have to look at the airframe I am installing the powerplant in and ask a couple of critical questions:

1) Am I going to be using this model and airframe extensively on a daily basis when it is in use or will it be used more for limited flights per day ?

2) Is the airframe being setup for more scale use or for endurance and durability ?

3) What are my finacial resources and how can these be best met by my choices of components on the final installations for completing the airframe ?

I look at my choices on these questions carefully and would pick a 4-stroke powerplant if I am building a scale model that is more for limited use and scale flights, where it will not be overly taxed by constant tug duty......this my be exemplified by an airframe that is being built for scale use, possibly for contests and similar flying.

If on the other hand I intend to have a tug that will be used for exstensive tug duty on any given day then I would definately use a gas powerplant as my optimal choice, buidling an airframe and engine combination that is specifically designed for high usage and dependability.

My final thoughts are to defer to others that have used the various powerplants at the recent aerotows and see what is working in the field mst successfully.

There are always many ways to make a great tug and use various powerplants to meet this end.

Bob

[Rossco]

Bet your brush cutter doesn't sound this good.....

http://www.youtube.com/watch?v=5Wph1eMDMb4

http://www.youtube.com/watch?v=Rqn49MGRuTw

[aerowiz]

The balance between Sounding good and reliability means a lot when its towing a $10000.00+ Sailplane.

Ill take reliabilty anyday. Sounds are just hot air,,,,,

[toobo]

Hi Guys,

take a look (and an ear) to this awesome 4-strokers: http://www.toni-clark.com/deutsch/se...ideo_VM210.htm

Yesterday a friend made his maiden flight with his 1:3 Husky, powered by a 120ccm Valach engine... just great! It has a very soft, deep sound and is very quiet. He towes my 6,33m Reiher without any problems.

I think the Valach VM 210ccm, 170ccm and 120ccm are perfect engines for any kind of tugs.
Here are more movies, towing with a ZLIN 134L powered by the prototype Valach VM-120-B2-4T http://www.toni-clark.com/deutsch/se...ideo_VM120.htm

[oldybutgoody]

My 4 cycle 5 cylinder MOKI radial makes a fine aerotow engine. It's reliable and has plenty of torque.

[aero104]

There is the soon to be released, Desert Aircraft DA-250FS.

http://rc-sf.com/?p=2539

Chris

Ps- also rumors of a DA-170FS.