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MVVS Exhaust option

Old 10-09-2005, 10:17 PM
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flyinrazrback
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Default MVVS Exhaust option

Are there any pitts style mufflers available for the MVVS 45? anyone have any experience running this engine on other than a tuned can?
Old 10-09-2005, 10:49 PM
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David_Moen
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Default RE: MVVS Exhaust option

Bisson Pitts muffler for a ZDZ60 for the MVVS 45, and seem to work well too.
Old 10-10-2005, 09:15 AM
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flyinrazrback
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Default RE: MVVS Exhaust option

any idea how much power loss over the can mvvs sells?
Old 10-10-2005, 09:28 AM
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rmh
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Default RE: MVVS Exhaust option

do you really want to know?---------
Old 10-10-2005, 09:36 AM
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flyinrazrback
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Default RE: MVVS Exhaust option

well, I figure its going to be about 300-400 rpm, but if the rpm on a stock muffler is still greater than the DA on stock muffler, thats fine for my application as the motor is lighter, unless I find another airframe to stuff a full pipe in.
Old 10-10-2005, 10:16 AM
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rmh
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Default RE: MVVS Exhaust option

Depending on the prop -pipe setups used - look for 500-1000 rpm losses .
One combo on the 26 MVVS= 2000 rpm difference! That's about half the power -
look at the "power calc's on props for a rough view of power to run given props at specific rpm's.
That 400 rpm can easily be 20% of power .
My own foolin around bears this out -- for example -- take a 26x10 mejzlic -pretty good sample prop for testing as they are very consistant in size/shape etc..
On Older in cowl muffler on ZDZ80 -- 6000 rpm
Now a 80cc tuned can - 6700
finally a tuned pipe -aprox 7000.
These are worst to best cases I have actually tried.

Look up hp differences on 26x10 menzs or Mejzlic -whatever - and note power for each 1000 rpm
On smaller engines the rpm spread is different but the curve is about the same.--In this instance -from about 7-11 hp spread
not perfect but a fair idea as to losses n gains.
Old 10-10-2005, 05:13 PM
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pe reivers
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Default RE: MVVS Exhaust option

It seems Dick uses an optimistic power calculator. I did not know the ZDZ 80 is that strong.
Here are the results from my calculations, using 1.18 prop load constant for Mejzlik
Power loss is indeed a typical 37% !!
engine 1
26.0 Inches
10.0 Inches
7.000 RPM
9.977 <<HP/kW>>
59.86 <-Lbs/grams->

engine 2
26.0
10.0
6.000
6.283
37.70

power ratio eng.2/eng.1
0.63

Prop load constants:
APC 1.15
Graupner 1.45
MA 1.00
Mejzlik 1.18
Mejzlik-N 1.12
MenzS 1.31
Zinger 1.20
3-blade 1.85
4-blade 2.50
Old 10-10-2005, 06:38 PM
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rmh
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Default RE: MVVS Exhaust option

I said it was rough- I just read directly from the chart - Iwas trying to show differences in power required at different rpm.
So what chart will show differences more accurately?
I am just looking at hp per rpm per prop -
When Iuse these darn things -Ialways think back to the Dream Wheels from my early hot Rod days - and the rather whimsical results .
The New ZDZ80J is actually stronger than the example I used -a fair bit
Old 10-11-2005, 10:59 PM
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Forgues Research
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Default RE: MVVS Exhaust option

How many people using these size engines are really interested in actually using a tuned pipe? I would say a fairly low %. So why even look at these numbers. Why not look at the numbers that most modellers will actually use.

Roger
Old 10-11-2005, 11:13 PM
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flyinrazrback
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Default RE: MVVS Exhaust option

Roger, I really like the pipes, I am the oddball. My 3W QS 106 on full length pipes was just nuts on them. 7300 on a mejzlik 28x10! Same thing with my 3w 150 on full pipes, just badd! I like the power, and most of all the quietness since I have a slight case of tinnitus (ringing of the ears). If I can find a plane to stuff a pipe in, thats what I prefer. However, most use pitts mufflers, but that just hurts my ears too much.
Old 10-11-2005, 11:19 PM
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Forgues Research
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Default RE: MVVS Exhaust option


ORIGINAL: flyinrazrback

Roger, I really like the pipes, I am the oddball. My 3W QS 106 on full length pipes was just nuts on them. 7300 on a mejzlik 28x10! Same thing with my 3w 150 on full pipes, just badd! I like the power, and most of all the quietness since I have a slight case of tinnitus (ringing of the ears). If I can find a plane to stuff a pipe in, thats what I prefer. However, most use pitts mufflers, but that just hurts my ears too much.
I like quiet also, but I would bet that most are not on pipes.

Roger
Old 10-12-2005, 12:04 AM
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Default RE: MVVS Exhaust option

ORIGINAL: flyinrazrback

Are there any pitts style mufflers available for the MVVS 45? anyone have any experience running this engine on other than a tuned can?

I'm confused. I know from other discussions that flyinrazrback would like to use a tuned pipe, but the original question here mentioned a tuned can, and flyinrazrback's approximated losses of 300-400RPM are reasonable for a tuned can vs a low restriction(relatively) pitts-style exhaust....but Dick started quoting losses relative to tuned pipes.....so what's the real question, relative to a tuned can or a tuned pipe?

Assuming it's the original question, flyinrazrback I think your estimate is in the ballpark....but since the 45 develops its power at a relatively low RPM, I wouldn't be surprised if the loss is on the lower side of that range.

BTW, if anyone has a ZDZ 60 Bisson muffler they want to send me, I'll test it out and send it back. Really. The results would be very interesting.
Old 10-12-2005, 06:28 AM
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rmh
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Default RE: MVVS Exhaust option

% wise - in the North American market - it is obvious most users will opt for a in cowl device.
The fact that they reduce hp from 20% to 40% and are relatively noisy has become acceptable here.
For those who are not satisfied with the "easy" path, The cans and pipes are welcome.
It is also acceptable to promote sales using power figures using cans/pipes etc., and dismiss the true losses as " somewhat less". It works for the car mfgrs
Again, Caveat Emptor.
Old 10-12-2005, 09:34 AM
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adrian-RCU
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Default RE: MVVS Exhaust option

i have a da 50 and a zdz 50 - i have two exhausts one the jmb pitts style and the other a supersonic style - the latter give me 800rpm more on both engines - one noisy and the other quite. 800rpm is lots!!!!!
Old 10-12-2005, 09:51 AM
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David_Moen
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Default RE: MVVS Exhaust option

To return to the original question, static rpm of 7100 on a Biela 22x8 and 7150 with a Bolly 23x8 carbon for the MVVS 45. Both of these engines were equipped with the Bisson inverted Pitts exhaust. More first hand data will be available as soon as I get my airplane finished!
Old 10-12-2005, 10:01 AM
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rmh
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Default RE: MVVS Exhaust option

Tuned can is a bad example --as tuned cans -tho "tuned" , are all over the map on actual advantage in power/noise levels and changing sizes of cans on a given engine further muddies the water.
Best starting point?
Let er rip -right out of the engine - adjust carb and get a reading.
This is square 1-the starting point for choosing acceptable exhaust setups
The best can so far -I think is the JMB line -really quiet -just use minimum length header . I find these to be equal to or better in power to open stack.
very acceptable on many engines.
The cans using the internal header AND a close proximity reflector, require a TOTAL exhaust to reflector distance that matches desired rpm band. Also the internal pressure , can and does affect power -sometimes quite a lot .
These devices were a puzzle to me till I hooked up a pressure guage to the cans and started reading internal pressures . This has to be done at aprox centre of the body -so it is not an option for testing by casual user.
I found that the best setups had between 3/4-1 pounds per square inch pressure in the primary expansion chamber . Also the total length from exhaust port to reflector, ran from 15" on 9000 rpm setups to 24" on 6000rpm setups.
Too short on header simply killed any performance. some setups making em worse than an in cowl restrictive muffler.
Ditto for tuned pipes -done incorrectly - worthless . And I see people blaming their incorrect setup on the pipe --- If you want the easiest setup with the least noise level -- a large open can -on a short header is the best bet - among all of these compromises.
Old 10-12-2005, 10:13 AM
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Default RE: MVVS Exhaust option

ORIGINAL: David_Moen

To return to the original question, static rpm of 7100 on a Biela 22x8 and 7150 with a Bolly 23x8 carbon for the MVVS 45. Both of these engines were equipped with the Bisson inverted Pitts exhaust. More first hand data will be available as soon as I get my airplane finished!

David,

Is that a misprint for the 23X8? I know thrustHP is not good for absolutes, but it is good for comparison. With those numbers it's 4.8HP with the Biela(which sounds close), and 5.8 with the Bolly. I'm getting 6000 on a 24X8 NX with KS 60cc can(engine new), which is pretty meaningless at this point, since I haven't even leaned it from factory settings yet. Dick I will test with an open header in the next couple of days and report here on what I get. I also have a 24X10 Mejzlik on the way which I should have on Friday and I'll report on that too, open and closed.

BTW David, do you have any 45MG's in stock? There is at least one person looking for one in this thread http://www.rcuniverse.com/forum/m_3293275/tm.htm .
Old 10-12-2005, 11:47 AM
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David_Moen
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Default RE: MVVS Exhaust option

Yup I've got lots!

The rpm reading on the Biela comes direct to me from a customer, the number for the Bolly comes from another post here on RCU. I find that folks running Bolly carbon props consistently report much higher readings than those running Mezjlik or Menz props. The only one I've had any first hand knowledge of is a 24x8 that we tried out on our MVVS 58 powered 30% Edge. We picked up 1200 rpm over the Mezjlik 24x10 we were running but the in-flight performance was poor.
Old 10-12-2005, 11:59 AM
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Default RE: MVVS Exhaust option


ORIGINAL: David_Moen

Yup I've got lots!

Great, I'll pass that info on.

ORIGINAL: David_Moen
The rpm reading on the Biela comes direct to me from a customer, the number for the Bolly comes from another post here on RCU. I find that folks running Bolly carbon props consistently report much higher readings than those running Mezjlik or Menz props. The only one I've had any first hand knowledge of is a 24x8 that we tried out on our MVVS 58 powered 30% Edge. We picked up 1200 rpm over the Mezjlik 24x10 we were running but the in-flight performance was poor.
I always thought the Mejzlik were about the lowest load prop out there, at least they are compared to other props I've run, but I've also never run a Bolly carbon to compare. It will be interesting to see what I get with the Mejzlik 24X10.
Old 10-12-2005, 12:44 PM
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rmh
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Default RE: MVVS Exhaust option

Bolly Carbon is the fastest revver of any I have ever tried- across the board.
That ain't all bad --or all good -just is .
I use Mejzlic -simply because in given sizes -they are all pretty repeatable -so we are comparing load.
I turn Mejzlic 22x8 at 7750 -on my 50 -on pipe - that is best fast response 3D prop -not the best setup overall for quiet IMAC but best instant spoolup -next best 23x8 Skorepa 7200 on the ground.
quietest -but excellent overall tho slower on 3Dresponse the Bambula 22x8 -under 7000 static .
Just match the prop to your specific needs .
Old 10-12-2005, 01:37 PM
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Default RE: MVVS Exhaust option

ORIGINAL: dick Hanson

Bolly Carbon is the fastest revver of any I have ever tried- across the board.
That ain't all bad --or all good -just is .
I use Mejzlic -simply because in given sizes -they are all pretty repeatable -so we are comparing load.
I turn Mejzlic 22x8 at 7750 -on my 50 -on pipe - that is best fast response 3D prop -not the best setup overall for quiet IMAC but best instant spoolup -next best 23x8 Skorepa 7200 on the ground.
quietest -but excellent overall tho slower on 3Dresponse the Bambula 22x8 -under 7000 static .
Just match the prop to your specific needs .

I really wish the author, or someone else, would modify ThrustHP to take into account the various prop loads such as provided by Pe above. It would make it a much more valuable comparison tool.

BTW, I know ThrustHp does this to come extent for a few props, showing thrust changes, but I want two things, more props in the list, and the potential for a reverse entry. Keep the HP constant and when varying the prop type, it shows the RPM changes.
Old 10-12-2005, 02:36 PM
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pe reivers
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Default RE: MVVS Exhaust option

On my website I have made available the current status of [link=http://mvvs.nl/prop-power-calculator.xls]my prop power calculator[/link].
Latest devellopment is the thrust calculation regarding prop disk load (power per area unit)
If you scroll to the right on the sheet, this calculator becomes visible. Provisions heve been added for geared application and input for gear efficiency. All rpm are prop rpm.
Interesting to note is, that if on a propellor the rpm are reduced, the specific thrust per unit of power increases. This shows, that it is better to get high power at low prop rpm. High rpm are detrimal to thrust, because disc load is increased!
Old 10-12-2005, 02:47 PM
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Default RE: MVVS Exhaust option


ORIGINAL: preivers

On my website I have made available the current status of [link=http://mvvs.nl/prop-power-calculator.xls]my prop power calculator[/link].
Latest devellopment is the thrust calculation regarding prop disk load (power per area unit)
If you scroll to the right on the sheet, this calculator becomes visible. Provisions heve been added for geared application and input for gear efficiency. All rpm are prop rpm.
Interesting to note is, that if on a propellor the rpm are reduced, the specific thrust per unit of power increases. This shows, that it is better to get high power at low prop rpm. High rpm are detrimal to thrust, because disc load is increased!
Very nice Pe. I didn't know you had that. Much more useful than thrustHP, especially since it can easily be modified to add different props. I'd love to see the Bolly Carbon, BME and NX props in the list.
Old 10-12-2005, 02:50 PM
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rmh
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Default RE: MVVS Exhaust option

Tha certainly makes the case for electric motor power --
Old 10-12-2005, 05:58 PM
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Default RE: MVVS Exhaust option


ORIGINAL: bpryor

I'd love to see the Bolly Carbon, BME and NX props in the list.
That can be done, if I have estimates on makes and power compared to known propellers in the list. The more data, the more accurate the compilement becomes, becaused it is based on basic propeller formulae, and adapted to field measurements.
Bolly probably would rate 1.0, along with Master Airscrew.
The number is not a quality rating, but just a way to compensate the calculations for blade geometry, and airfoil. If a prop does not perform as expected, measure the tangent pitch (ancient NACA style) at 1/2, 3/4, and 7/8 diameter stations.

@ Dick,
There is no difference between electrics and combustion engines, since both produce power wich results in prop rpm. Only in electrics, gearboxes are more common. The sheet can be used to predict the influence of i.e. a 1:1.5 gearbox with drive type (chain, belt or gear) and subsequently needed prop size, along with pitch needed for the required air speed. (one mile is 1.6 Km)

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