Hi all, just wondering if any one had any ideas to try to sort out my MVVS .49 (2001 model)
It is box stock running following set up: 2 factory supplied head shims,factory supplied plug, factory front mount nva, 10/22 (50/50 castor synthetic) home brew fuel,
rear muffler (non piped)
Have tried  zinger 12x5 and  ma 12x6 props, Strong constant 4 stroke with zinger (good airspeed) and likes to break to 2 stroke with the ma.
Problem is on current model (670 squares, a bit portly @ 66 oz) it could use a bit more power in windy conditions but if it is set up to 2 stroke it breaks far too late (like late on downward leg of triangle about 3 feet before last corner!)
Do I build another model for it and try to improve power to weight ratio (current model doesn't fly a real bad corner).
I like the constant airspeed when running in a 4 stroke, but don't want to cast off a model that I think still has potential as my building time is a bit limited at the moment, (which is one way of saying I've got too many fingers in too many pies)
Any ideas greatly appreciated.
Thanks Rob.

 Bill, you know I have read about changing venturi sizes to gain more hp or throttle back an engine probably about 20 times in the last few years and it never occurred to me to try it this time around. Couldn't see the forrest for the trees I guess. So I think I'll try that next. So far I'm really happy with how the engine handles and it seems to run quite strongly but she just wants a little more.
Thanks for the enlightenment, Rob.

  Thanks Fred, I tried to reply sooner but have been having dramas with my internet set up.
  I had no idea that the .49 would pull that much prop. The model I have the engine on is limited to 12" props by the undercart (fuse mounted), so I think I will start on a new model and am seriously considering the SIG MAGNUM as a starting point. I now have a plan thanks to Wynn Robins.
  Hopefully I can get weight sub-60 oz. using strip ribs and conservative "jam" job.
(this could be a challenge with 12 oz engine)
  Certainly more experimentation with props, venturies is in order.
 Thanks again, Rob Biddle.

Ive been trying to locate one of the new MVVS 49 Acrobats.  I find lots of vendors that are supposed to have but do not.  Anyone know of a reliable source?  Anyone have one for sale?

Thomas

Guys,

I purchased a new MVVS 49 Akrobat which was set up as a FIRE by the factory,  also bought at the same time, the MVVS rear exhaust muffler set up.

These were purchased from a friend in Israel who buys direct from MVVS factory.
It may be difficult to get anything from Israel right now.
 
Look on RC Universe at the MVVS support forum, he is one of the support guys.
He can't advertize on RCU but he can be E-mailed thru the RCU site.

Or, send me a PM or E-mail and I will give you his address.  Also, I think there is an ad in Stunt News of an MVVS dealer.

Jim 

Charley Pate refereed to a 13 x 5/6. It was a 5in pitch
Zinger Pro with the airfoil thinned and a slight reduction in blade area.
As he stated it surprised us that the engine would turn that much prop and be happy.

It made an airplane that was barely flyable with a K&B 40 into a very good practice plane, after  a tip weight issue was resolved. It was my first experience with an equal panel wing and I ended up with over 2 1/2 oz of tip weight. I don't like carrying that many passengers.

I noticed on the gold head it has two grooves cut into the smooth portion . I own two of these engines one has the green head and one is natural aluminium . The natural aluminum headed one has the same two grooves as the gold head in the photo. Are both of mine high comp. no nitro style engines or is the natural alum. headed one a low comp. more nitro style. Can I easily convert them too a gold head(low comp style)?I want to put one of them with RE and short pipe in a Whitely Shoestring.

Thanks for the info , I will pull the heads off tonight and report what I find.

Here is what I found. The green head is two piece and has four .085"shims, the combustion chamber is like the one in previous picture . The natural aluminium head has a combustion chamber configured like the gold head. The pinch at the top of the piston stroke is too tight to be able to get a deck height measurement. I will put the heat gun to it in the next couple of days and see if I can get some compresion ratio #'s . The green head engine came equiped with a .196" dia. venturi and the natural alu. headed eng. has a .191"dia. venturi. I need to get some parts before running these engines such as a new needlevalve(this one is bent) and prop nut and washer. I would also like to score a new gold style head and more shims so I can set up both the same . The green head version will stay standard side exh. and use the fairly light weight muffler provided ,while the later version with the natuarl alu. head will stay as a rear exh. and utilize what looks to be a shorty tuned pipe but without pressure nipple. If memory serve me correct this one I got from our host(Sparky)

For the engine only:

Just Engines' price is 75.95 Pounds or 111 Euros. (approx $141).  He charges 5 pounds for RE setup.  So this is about $150 setup RE, BUT there is a deduction for non-EU countries x .851 (no VAT tax).  Total - approx $128

Alberto's price is 95 Euros (approx $121).  This comes setup for RE.

So these 2 suppliers are pretty close in price.

You will have to contact the sellers for their current shipping rates.

Fred