NikolayTT

Dear Fellows,

If the weather is windy most of the time flying slow is not much pleasure.
I am not going to compete in any class, just would like to have good sport
flying with basic aerobatics, and anyway as fast as possible to "offset" the
wind interference on my pleasure as much as possible.

Could you please help with advice what one could do with MVVS-26 Glow
in order to have a bit faster than standard RC-plane ? Some of the specific
questions are below, but please do not be restricted by them:

1. What RC-plane would permit speed in the range of 120-160 km/h or even higher,
and also will look nice, maybe scale-type like Lancair or Mustang or .... ?

2. Which type of Servos to use, Receiver battery type, and should it be or not 6V, etc ?

3. Engine should be run on open exhaust or use a tuned pipe(which one) ?
At the airfield where real size Cessna and Extra are run the noise is not an issue.
Tuned pipe cost money and adds weight but how much the power boost is ?

4. Which propellers to be tested on the particular RC plane; diameters, pitch, brands etc. ?

5. What Fuel, how much Nitro and which Glow plug (4S or not ) for temperature range of 10 ... 30 deg.C ?

6. Fuel Tank-size, Perry Pump or direct Crankshaft-pressure; please advice what is most sensible approach.

7. Smoke: What could be the most efficient way to make it with MVVS-26 ?

Also if you know some similar posts, please let me know their links too.

Thanks in advance,
Nick

pe reivers

I would suggest to run the 3266 tuned pipe with 3265 header (by MVVS)  and a Mejzlik 16x14 prop
The tuned pipe has a distinct power advantage. If noise is not an issue, you can open up the rear damper chamber.
If you shorten the header and use a 16x12 prop in the 9000+ rpm range, you may even be slightly faster.
Use an extra shim under the head, and add some extra nitro. That will bring you a few extra rpm as well.
Build your plane clean, without parts sticking out, and use a plane design that has smooth lines and allows to have the pipe inside the fuselage.
There are some about if you look for it.

NikolayTT

Thanks a lot Pe !

NikolayTT

Hi Pe, and also anyone who is familiar with the MVVS tuned pipes,

I do not have exact idea how to open the 3266 tuned pipe at the back end in order to get
max-power of the system, regardess of the noise level?
There are 3 bolts but it seems the back pannel is glued or stuck with red-brown rubber and
I am not sure I know well enough what is the structure of the silencer-part of the system.
- Any drawings or photos, preferable with dimensions (at least some) would be very uselpful please.
Then some possible ways to get "rid" of the silencer-compartmet, which is reducing the
overall power and also adds considerable(!) weight might be:
1) Drill the back pannel ? But in what place with what diameter and how deep, etc ?
2) Dissasemble the back-pannel? But how to do that in the presence of that red-brown glue or rubber ?
3) Cut the whole silencer compartment out ? But where to cut so to not damage the resonance compartment?
4) ... please advice what is the best thing to do in case:
A) to be able to restore the original setup if/when needed ?
B) to be able to make it only resonance pipe with min-weight without restoring ever the silencer ?
Anyway, any advice of getting Max-Power-Output of the MVVS26+ResonancePipe
regardless the Noise-level are very much needed and appreciated.
- By the way, looking for an Aeroplane which is matching the requirements for higher speed did not produce
much results. Surely there are all nice Classic Aerobatic ones, but with their thick Wings the speed is not
going to be pretty good. I checked quite many RC-shops without result. Please advice which one would be
the one ?

Thanks, Nick

pe reivers

try http://tech.flygsw.org/all_about_evolution_26_gt.htm (mark Fuess)
e had a nice discription.
Any sleek plane, not too large will be fast! Aim for 180cm max span. Don't shy away from kit bashing to get the engine inside.

NikolayTT

Thanks Pe !

The info about the tube is very good and sufficient for me to make my mind.

Nick

pe reivers

Have you had a look at the sundowner by horizon? 16x14 prop, trimmed for best performance should do it.

NikolayTT

Yes Pe, this is a pretty choice of arplane ! I contacted Horizon but they do not ship directly to
any person in Finland and I could not find even this Airplane available from Germany too...

I will try to get it from some other places if available. It looks very nice and that is a "must have" signal ...

Also I have the "nasty" idea to strenghten with lot of epoxy & fiberglass the fuselage and also to
cover with balsa + fiberglass the wigns and controls of the Great Planes Lancair which is
origianlly designed for up to 15cc engine and has about 2100 cm wings. It is pretty fast
even with 15cc as people reported but it was too "crispy" and been faling apart in overloads.

The other idea is to modify and strenghten the Grauper's Extra-300S which is also designed
for up to 15cc.

Also I tried to look at some good Pattern Flyer like the Phoenix-6 from 70's which has pretty
good shape but maybe it is a bit too small.

Any comments on those please, what would be the best out of those 3 in case if I cannot get
the Sundowner ?

In the next post I will place what I learned and have a question on the tuned pipe.

Thanks,
Nick

NikolayTT

After reading the
http://tech.flygsw.org/all_about_evolution_26_gt.htm (mark Fuess)
as said it is very good advice how to do it.

But I got a bit confised. I was expecting to see that there is reverse conical surface in the
MVVS mufler but it appered to be just disk. Surely it has been well experimented and tuned
to fit the MVVS26.

The question in my mind is: - Would be biger boost of the power if I would use the classis
two-cones reso-pipe of Macs, for example in http://www.macspro.com/tunedpipes.asp
the models # 1195 or # 1196. Maybe you or some of your contacts have tired those on
MVVS-26 ? - please comment.

Thanks,
Nick

pe reivers

The MVVS pipe is very well adapted to the engine. Double cone pipes not necessarily provide more power. So far, the mvvs pipe stood up to competition designs with multiple cost tags quite well.

NikolayTT

Yes Pe,

Tuning of the pipe seems (to my limited experience) pretty dfficult job and MVVS have been doing very
much work obviously on that. Also the price of the Macs pipes is almost twice higher. Looking in the
dimensions it seems the Macs 23" lenght without mufler is equal to the MVVS with mufler section...
That rises the Question: - While cuttng off the mufler section of the MVVS pipe it is maybe needed
to consider the "kick-back" effect of the pressure accumulated there on the pressure in the resonance
compartment, and then on processes in that compartment. Certainly, this will change the pattern of
the waves in te resonance section and thus the MVVS power boost effect might be influenced more
by the disk reflector while there isn't a mufler section...
In order to be fair to Macs and MVVS maybe I should think that I am not comparing anymore MVVS
original pipe with Macs but a MVVS modified (damaged by me cutting off mufler) one. In this sense it
might be the case that Macs gives more power than the MVVS-modified on, what do you think ?

P.S. In other words, I wander if in the Tutorial below was the right thing to cut out the whole
mufller section; why not about the 'half' of it or to cut piece-by-pice and watch te power boost
so to account for the new constellation of the processes in the resonance pipe ?

http://tech.flygsw.org/all_about_evolution_26_gt.htm

I hope all this makes good sense also for the Scale-Ricing guys which as Pe suggested have been
very mich talking about F1 raing with Sundowner and using MVVS/Evolution 26 or 35.

But I do no know how to link those two forums so the current discussion appears in the
Scale-Racing too; please advice.

It seems Very Hot Discussion at

http://www.rcuniverse.com/forum/m_57...tm.htm#9190172




Nick

pe reivers

Nikolay,
You ask yourself too many questions. Keep it simple please.
Mark Fuess did not change the reso pipe section or lay-out. He just made the header shorter in order to get more rpm. He also reduced back pressure by completely removing the muffler section, which probably would allow the engine to run cooler. A different muffler could do the trick as well, if it has better breating (lower back pressure) than the MVVS muffler. I would add a low-pass muffler section if I had to modify the MVVS device, but results seem uncertain. Noise is a no-no at European clubs, so a muffler section is required.
If you look at his pictures, running cooler is very much needed, because the liner of his engine has turned blue. This cooler running by itself will increase power, which may have convinced him of the limited flow theory.
The liner should stay without any discoloration if the cooling is sufficient.

NikolayTT

Thanks Pe, I just simply didn't think yet about the cooling...

pe reivers

The new MVVS tuned pipe for the 43, 50 and 58cc engine just has emerged.
It is of the same design, and promises a tremendous boost at elevated rpm, like about 10hp from the 58 at about 8000 rpm. That is 2 hp over the tuned pipes I tested so far.
If the pipe is anywhere near as docile ast the 35cc pipe, they have a winner. It is however longer than the MTW-RE2 pipe, but needs a short header, so total length measured frompiston skirt is about the same..

yarrabubba

MVVS 58 IRS # 3001

The IRS model is listed as 8.5hp on MVVS cz pdf manual but on their website it states the below

IRS 6.8hp
Prosport 7.0hp
Liquid Cooled 7.2hp

If you could clarify the correct specification would be greatly appreciated.

Thankyou

Brent

pe reivers

all values are correct, depending on exhaust system and operating rpm.
BTW, you sent me two mails, of which I answered one. Don't do this!

pe reivers

With the new tuned pipe from MVVS, the engine ran a Mejzlik 24x10 prop for short duration at 7400 rpm. That was 8.7 hp! The power could not be sustained, indicating that torque at that rpm was not yet at it's best, and more power could be had by using a smaller prop. After discussing matters with the customer, and because the engine was intended for a glider towing contest, we decided to keep the prop, and adjust the header length to bring best torque to lower rpm. End result was that with the Mejzlik 24x10  the engine now runs up to 7400 rpm again when hot, but without sagging when the pipe gets hot.</p>

Final header length was about 20cm.</p>

mrbiga

Hi, what glow plug ( os 8 or os 4f) must i use in my mvvs 26 . I use the 3270 mufler and 5% nitro 18% oil fuel (80% synth+20% castor)

pe reivers

Novarossi C6 or equivalent. OS #8 may be slightly hot. Enya 3 or enya 4 would be better.