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Prop for a MVVS .15D

Old 06-05-2009, 10:11 AM
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franchi
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Default Prop for a MVVS .15D

Gang:

I dug our my MVVS .15D after it had been in storage for about 26 years I test ran it prior to putting it on a Dumas Tom Tom stunter and the question I have is,what size prop should I use?.In the past, I had only used 7-6 and 8-4 props. I tried a 9-5 prop and it ran quite well. Oh yes, I did not realise it at the time, but I never leaned out this engine in the past. I turned the n.v. in about 1/2 turn and this thing really turned on the speed!

Will I overload this engine with an 8-6 or a 9-5? With the smaller props, it flew fery well in the past burt now I think that I may have been underpropping this engine in the past. Any ideas?

I bought this engine in the early 80's for 36.95. It has front intake with a rear exhaust stub and looks it was sand cast. It also has two ball bearings. I only used it for a sport engine. It starts very easily and is a pleasure to use. Any information about this engine? It is a shame that MVVS stopped making small engines!

TIA,

Franchi
Old 06-05-2009, 11:14 AM
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AMB
 
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Default RE: Prop for a MVVS .15D

I have mine about 3 yrs old in a cub 50 inch span 10inch MAS black prop the numbers are worn off either a 10x5 or 6 if memory correct turns in the mid 8 to low9K no issues no overheating Next time out will try A WOOD XOAR electric 10x6 blade will be more efficent. It has the stock MVVS
3225A side mount and exhaust piped to rear of the plane my conversions use these and my OS and TT10s with Davis diesel heads great park flyers and QUIET with these power plants with the demise of the MVVS 15 diesels the OS and TT 10s davis conversions are my choice and I would say equivlent in preformance and most important available for my use martin

as before fuel flip fly no battery charging hassels a


Old 06-05-2009, 12:15 PM
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gkamysz
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Default RE: Prop for a MVVS .15D

9x5 makes a nice sport prop. I flew one in a trainer for a summer when I first started.
Old 06-05-2009, 12:52 PM
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pe reivers
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Default RE: Prop for a MVVS .15D

8X6x3, 9x5,10x4
Old 06-05-2009, 12:57 PM
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Default RE: Prop for a MVVS .15D

Pe thx will pick up a 10x4. the new MVVS you sent perfect, contra smooth as silk test run only ,about a tank DAVS ABC mix
Old 06-05-2009, 02:45 PM
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Jim Thomerson
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Default RE: Prop for a MVVS .15D

Here is a copy of one of my posts on another forum.

The MVVS 2.5 cc, Aeromodeller, Aug.,1997, has a diffeent shaped torque curve; peak torque is almost 30 inch-ounces at 17,000 RPM. Peak horsepower is 0.56 at 20,000 RPM. Said to turn a 10 x 3 at 10,000, but peak torque prop woud be an 8 x 4 at 16,200. Peak HP would be a 7 x 4 at 19,300. So this is not a slogger.
Old 06-05-2009, 06:48 PM
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paw080
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Default RE: Prop for a MVVS .15D

ORIGINAL: franchi

Gang:

I dug our my MVVS .15D after it had been in storage for about 26 years I test ran it prior to putting it on a Dumas Tom Tom stunter and the question I have is,what size prop should I use?.In the past, I had only used 7-6 and 8-4 props. I tried a 9-5 prop and it ran quite well. Oh yes, I did not realise it at the time, but I never leaned out this engine in the past. I turned the n.v. in about 1/2 turn and this thing really turned on the speed!

Will I overload this engine with an 8-6 or a 9-5? With the smaller props, it flew fery well in the past burt now I think that I may have been underpropping this engine in the past. Any ideas?

I bought this engine in the early 80's for 36.95. It has front intake with a rear exhaust stub and looks it was sand cast. It also has two ball bearings. I only used it for a sport engine. It starts very easily and is a pleasure to use. Any information about this engine? It is a shame that MVVS stopped making small engines!

TIA, Franchi


Well, Hello Again Franchi, for control line, you can use the following props: 8X6, 9X4, 9X5 and a 9X6. Each prop will give a different kind of
flight. Do not use a 10 inch dia prop because the Tom Tom will fly too slowly for a control line model; giving too light a line tension...okay
for RC and an old time FF models, but just won't do the job in C/L.

Starting with an 8X6, this will put your Tom Tom into a fast flying mode, and feel somewhat like a slow combat ship. We used various 8X6's
to fly our 80 mph speed limit combat models. my friend Bare's MVVS 2.5D powered 400sq" combat model flew 82 mph with a Master Airscrew 8X6, without a streamer.
I was getting 79mph with my ST .15D RV in a 360 sq" model. This speed is on 60' x .015" lines. I fly my sport .15 diesel powered models; a Veco
Tomahawk, Dumas Tomahawk and a CLC Super Clown with 8X6, 9X4 and 9X6 Taipan props depending on my mood. The 9X4-9X6 props will
provide a slower and smoother stunt speed like flight, which also is a very enjoyable,less frantic experience. Come to think of it, you can also get
away with using a wood 10X4, I have used a Rev-Up 10X4 on my very light Dumas Tomahawk(17.5ozs)..as pe reivers
suggested.

For those unfamiliar with these designs, they are listed as suitable for .19-.35 engines from the 1950's -1960's. I believe MVVS still makes the .15D.
I have one with the rotatable barrels and no anodyzing. It spins a 9X6 at almost 12K...very powerful.

Tony G


Old 06-05-2009, 06:58 PM
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gcb
 
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Default RE: Prop for a MVVS .15D

I would suggest a 9x4 or 9x5 for that plane. The Tom Tom (originally VECO, then Dumas) is not a large plane.If I remember correctly, it has ~40" wingspan. The MVVS 2.5 should be a good match.

The first larger than 1/2A plane I flew was a Tom Tom (belonged to a friend). He powered it with a McCoy .29RR GOLD head (gold was the lowest compression).

George
Old 06-05-2009, 10:26 PM
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mylamo
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Default RE: Prop for a MVVS .15D

I have been using an APC 8X5 for 30 ounce RC planes
on both of mine and they love this prop.Goes to show
what a great little engine this is. If you want a screamer
on a light plane or a slower turner it does it all.
Ralph
Old 06-07-2009, 10:00 AM
  #10  
franchi
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Default RE: Prop for a MVVS .15D

Hi All:

I flew the MVVS .15D on the Tom Tom today and it was great. I used a 9-5 prop and it proved to be to fast for a stunt plane! I was using .012X52 foot lines. Perhaps I will switch to .015 X60 foot lines to slow the rotatational speed a bit. I could go back to 7x6 or an 8X6 prop to slow thindgs a bit. Of course I could slow the engine down a bit also. The person who "pitted " for me had the engine overcompressed and running too lean for the first flight. I will stop permitting others to adjust my engines. I know more about my engines than the "experts."

Franchi
Old 06-07-2009, 03:00 PM
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gcb
 
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Default RE: Prop for a MVVS .15D

I would suggest trying the 9x4 and 60' lines. That will give you slower lap time and maintain thrust in maneuvers.

George
Old 06-08-2009, 11:17 AM
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paw080
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Default RE: Prop for a MVVS .15D



Hi Franchi,
Hmm...for some unknown reason, your quote was truncated........Anyway, you should be flying
your model on 58-60' lines. Also, a 7X7 and an 8X6 prop will speed your model up; not slow it
down!

Tony G

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