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Old Dec 10, 2003, 09:11 PM
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MVVS 2.15 (35cc) gas as a tug engine?

Hello all,

I have the opportunity to buy a barely run (4 tanks on the test stand only...never flown) MVVS 35CC gas engine for a fairly good price. The questions is, will this engine suffice for a tug for medium sized scale planes? The performance of the engine can be found at the bottom of this link:

http://morrishobbies.com/reviews/MVVS_215_3.jpg

Any ideas of how large a plane this will comfortably tow? I have a Rodel 4.2m K-21 that it will likely easily tow, but what about a Rodel Fox? A 4m, ~14lb Minimoa?

I have not thought of an airframe yet...any suggestions? This motor is probably a bit small for a Pegasus, correct?

It is about half the price of any DA engine I can get my hands on, and significantly cheaper than most Zenoahs.

Any input is appreciated.

If this is a false economy to buy this engine, I would appreciate hearing that, keeping in mind that we are not towing 6+m planes, and likely never will...plus there is another tug in town that is in the works to tow big monsters.

Thanks,

Ryan.
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Old Dec 10, 2003, 09:26 PM
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35cc towing

I used to tow with a senior telemaster type plane powered by an OS BGX1(35cc) glow engine. I did tow the Rodel 4m foxes a couple times. It is a bit marginal, it can be done with two good pilots. The ground run was quite long and it was important not to climb too steeply and on the other hand the fox will quickly overtake the tow plane if you are not at least flying level. Ron Wahl once towed a 25 lb. 5.3m duo discus with his BGX powered telemaster at the second Elmira meet. So it can be done if everything is done correctly.

You can get G62's used for cheap, I would go this route for towing 4m foxes and bigger - it is much easier for everyone.
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Old Dec 11, 2003, 10:22 AM
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Thanks for the comments. Personally, I have been sold on the idea that the Telemaster makes for a crappy towplane. If I were to use the MVVS in a better airframe with a far wider speed envelope, would you still not go for it?

How much more power realistically is the G-62 than the MVVS?

Thanks,

Ryan
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Old Dec 11, 2003, 09:13 PM
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A G-62 will produce about 22 pounds of static thrust with a 22/10 prop from my memory. I am skeptical of the preformance report on the 35 cc motor pulling 20 pounds of thrust, but who knows, maybe it is a breed apart.
Besides static thrust is only part of the equation. Once flying and pulling, Dynamic forces intervene.
The only way your'e going to know is to buy it and try it, but a 60 cc is a good starting point for faster heavier sailplanes. An improved, (IE: wider speed envelope tug) may or may not help. The Telemaster has its problems, especially landing, it does not want to, but for a first tow plane it does have a few advantages provided your flying on calm days and don't need to rush down and land quickly.

You might lookat a medum sized Lanier Stinger or similar, all up weight in the 17-20 pound range.

John Derstine
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Old Dec 12, 2003, 09:58 AM
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John,

I too am a little skeptical of the power output, though I have done some searching on the web and this motor is definitely a powerhouse based on may people's experiences. Whether it's actually as strong as a 62cc engine is debatable (and questionable in my mind) I guess the one advantage is it's bound to be a lot lighter than a G-62.

In your opinion, what is the best bang for your buck engine...factoring performance and reliability/startability into the equation?

I would say that 60cc is about my top limit for displacement.

Thanks for the input,

Ryan.
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Old Dec 12, 2003, 05:22 PM
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The default 60cc class motor has to be the G-62 both for price and reliability. Get a spring starter for it and it is easy to start. With a simple magneto ignition, it is easy to use and maintain.

The best in the class... the DA 50.

John

http://www.scalesoaring.net
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Old Dec 13, 2003, 12:27 AM
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Quote:
Originally posted by scalesoar
With a simple magneto ignition, it is easy to use and maintain.
This brings to light another question...what are your feelings on a magneto ignition? It's likely simpler, but are the reliability and performance gains of an electronic ignition well worth it?

Also, you say the DA50 is the best...what are your reasons? Balance? Power? Startability? Is the DA the kind of thing I would end up with a few years down the road anyways, or can I tow long and happily with a G-62 for many years to come?

Thanks for your help to this point. I'm still trying to decide the viability of a gas tug, since my worry still revolves around convincing the glider club to allow a gas plane at the field (even though the focus of aerotow is still on flying gliders)

Has anyone else out there successfully taken their club from a TD only club and brought in scale aerotowing? I would love to hear your experiences.

Thanks again,

Ryan.
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Old Dec 13, 2003, 07:38 AM
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Magneto ignition is cheap, convenient, and does not require separate batteries to create spark. the main drawback is the timing is fixed, that is why mag motors are notoriously hard to start, they optimize the timing for running at higher rpms. That said, the G-62 is one motor that will not run any better on battery ignition than mag, and if you add a 50 dollar spring starter it is a snap to start. There are other means like the "jumpstart" which temporarily retards the timing for starting, wher upon you disconect the device.

Battery ignition motors generally run smoother and develop more power across the entire rpm range. This is why the big boys use them in the large aerobatic planes.

A G-62 is fine for towing and you will not wear out any gas motor in less than 1000 hours, they take 40 -50 hours just to completely break in.

G-62's are heavy and by the time you add a spring starter and good muffler plus aluminum mount your in the 500 dollar range.
A DA 50, or BME 50 (both top of the class) will run you only a little more.

John D.
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Old Dec 13, 2003, 11:47 PM
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ZDZ 40 or 50 also work!

John Derstine will vouch for it, I used a H9 Taylorcraft and a ZDZ 40cc to aerotow with. It is a great little set up for 4-4.5 meter sailplanes or 15 lbs and under. I have used it on planes up to 25 pounds and 6 meters but it is a little slow to get it up and you have to be careful to keep the speed up(slow climb) with the bigger sailplanes. (I'll mention I have it for sale but you need to be near Pensacola Fl. to get it. Making boxes is not my cup of tea!!) Any of the 50cc motors mentioned would fit the same plane and provide even more thrust for only a few ounces more than my set up. That said, if you even remotely think you'll be towing 6 meter planes(or bigger) down the road something in 80-100cc class planes would serve you better in the long run!

Steve Rojecki
Team JR
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Old Dec 14, 2003, 12:16 AM
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Steve - could you give me a rundown on the flight characteristics of the H9 Taylorcraft? I really like the looks of that model, and I'm curious how it flies. Not neccessarily as a tug, but even as a sport model.

Cheers,
Adam
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Old Dec 14, 2003, 08:14 AM
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Re: ZDZ 40 or 50 also work!

Quote:
Originally posted by rojos
John Derstine will vouch for it, I used a H9 Taylorcraft and a ZDZ 40cc to aerotow with. It is a great little set up for 4-4.5 meter sailplanes or 15 lbs and under.
Steve Rojecki
Team JR
Absolutely Steve. I wasn't purposly neglecting the ZDZ motors in my comment, just giving what I felt was the top and bottom possibilities. The ZDZ's are a good value. I had an early ZDZ 80 single on a Pegasus once and it had very nearly the same performance as a Brison 6.4 twin.

I have been toying with the idea of converting one or more H9 kits to tow duty as an experiment. I thought perhaps the Super Cub and or the Cessna Skylane. The kits are very well built and with a little beefing up in the right places might make excellent tow planes for the medium sized sailplane.
I was thinking a 3.2 Brison could be fit on the Cessna and maybe on the Cub, although on the cub, I think that might be overkill, there is where the ZDZ 40 or 60 might fit better. I have to go look at the airframe sometime.
A friend of mine's son Darryl Tenny, (AKA Sierra precision) makes a nice upgrade scale nose gear for the Cessna.

JD
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Old Dec 14, 2003, 08:20 AM
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This is the Pegasus with the ZDZ 80. At the time I was experimenting with canopy ideas, this was not a good one :-)

I used a tuned pipe inside the fuselage, it was a very clean installation and quiet also.
JD
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Old Dec 15, 2003, 12:15 AM
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Navarre,Fl
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H9 T'craft

Adam,

T'craft is a great little airplane does all your basic stuff, loops rolls spins and with the ZDZ 40 will hover/torque roll(not exactly scale!!) Touch and goes are lots of fun. It is an easy conversion to set up for towing. For just sport flying a G26 would be the perfect setup or if you like glo go with a 4 stroke 120-180.

John,

Pete Goldsmith and I thought the 182 would make a cool tow plane for smaller gliders. I bet you could get a 50 cc in it no problem(prop clearence might be an issue/ use a 3 blade) The ZDZ 40 is basicly the same weight/size(the 50cc motors are just a smidge heavier) as a G26 so it should work. I'm already using the H9 Super Cub as a tow plane with a twin Hacker B50 set up. Pulls 4.8 meter(13 lbs) DG 600 no problem. Pete and I have done up to 4 pulls on a charge(Thunder Power 7800mah).

By the way is the Ventus on it's way. My Christmas tree looks a little bare right now!!!


Steve Rojecki
Team JR
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Old Dec 15, 2003, 09:29 AM
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Re: H9 T'craft

Quote:
Originally posted by rojos
I'm already using the H9 Super Cub as a tow plane with a twin Hacker B50 set up. Pulls 4.8 meter(13 lbs) DG 600 no problem. Pete and I have done up to 4 pulls on a charge(Thunder Power 7800mah).
Now that sounds like a big buck setup!!!

What size prop are you spinning, and at what speed?
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Old Dec 15, 2003, 01:44 PM
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H9 Electric Tug

Twin Hacker 10XLs on an Inner Demon 5 to 1 swings a APC 24x12 electric prop and I used 2 4S4P Thunder Power Lipos. I have never tached it. I have pulled up to a 25 lb DG 800, but it was a little marginal. 15 lbs and under worked great. As for money, yea it's a more than a gasser, but very little noise, vibration, slime and a cool factor thats hard to price. It is a viable set up if noise pollution is a problem for you.

Steve Rojecki
Team JR
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