Real world RPM

[Alexzzz]

Could anybody tell me the difference in rpm between a Mejzlik 30*12 and 32*10? (both 2-blade)

Thanks.

[krayzc]

Looking back at the data it appears to be about a 400 rpm

30 averaging about 5900
32 averaging about 5500

On mufflers give or take

[pe reivers]

	Quote: Originally Posted by krayzc
	Looking back at the data it appears to be about a 400 rpm 30 averaging about 5900 32 averaging about 5500 On mufflers give or take

The 32x10 has a higher power demand.

[Al Lewis]

DL-50
Stock Muffler
Vess 23A
Belray H1R 40:1
7400 rpm

[juanes1969]

3W 85xi, in-cowl johnnson muffler, 40:1 break-in oil, 5 gallons:
mejzlik 26x10= 7100 rpms
mejzlik 27x10= 6600 rpms

[pani]

DA 50 not run in yet (2nd gallon)
20 ft elevation
Stock DA Muffler
30:1 Castrol mineral oil with 95 RON unleaded
Vess 22A 7400rpm
Metts 22x8 7240rpm

DA 50 (8 gallons)
Bisson pitts style
40:1 Redline racing oil with 95 RON unleaded
Metts 22x8 6750
Same engine cut muffler exit ends
Metts 22x8 6880

[drewbags]

DL100, KS Cannisters, 2 Galls 50:1 Mineral, 6300rpm on Mej 28x10.
SL +15 Deg C.

[tomyrcmodels]

MT-57CN
MT header and canister mufler
TBM 23-8
7600 rpm
,

[RustyTumbles]

After a 10min flight

DA85, KS95 rear exit can, 27x10 Mejzlik

6060rpm

[Flatlandman]

DA85 / slimline pitts / Mezjlick 27x10TH
6 gallons of Penzoil 2 Stroke air cooled breakin
85° unknown humidity
6350 RPMs

[pelle_gris]

Zenoah ZG-62
Toni Clark stainless steel "Piper" muffler
Toni Clark 90° carb bend, and inlet "trumpet"
Sea level, temps around 20°C.
95 octane with 2% Stihl or Husky oil.

MenzS 19x10: 7400rpm
MenzS 22x10: 6600rpm
MenzS 24x8: 6200rpm
MenzS 24x10: 5800rpm
MenzS 26x8: 5300 rpm

MenzS 24x10, standard Zenoah "box" muffler: 5000rpm
MenzS 24x10, Toni Clark muffler, see above
MenzS 24x10, no muffler: 6200rpm
MenzS 24x10, Krumscheid tuned pipe: 6700rpm

MenzS 28x12, no muffler, Reeves belt drive: 4600rpm
3W 32x12, no muffler, Reeves belt drive: 4000rpm

BRGDS
Tinus

[John63]

DL-50 whith standart muffler on Mejzlik 22x12 6300 max. 1500 idle.

[Scott Gerber]

DA-50R
Stock side dump muffler
Vess 23A
Bel-Ray MC1 50:1
89 octane (starting on 5th gallon)
6670 rpm (needles at factory settings)


Scott

[staudman]

I ran a 3WQS150 on a 29-12 Mejlik 3 blade and tached 5700 RPM....
The temps were mid to high 70s with low humidity.
Engine is on Dalton cannisters with KS headers ,about 10 inches long...made at home....
Its a perfect day to fly and I am sttuck playing with engine/prop and airframe issues....!!!!
CRAP!!
At least tomorrow is SUnday!!!
C YA at the FEE-ELD!!

[pe reivers]

Rich,

the constant of 1.27? was that as used with 8" pitch in the chart?
so 22A vess could be 22x8 and 1.27 constant.
Did you input your altitude level? It has a large influence on static thrust.

	Quote: Originally Posted by soarrich
	I've found that for the Vess 22A and 23A the 1.27 prop constant to be good. I don't think I tested with a B Vess yet.

As for your question about the math:
Mainstay are the Abott-Boucher calculations, (dia^4, rpm^3, pitch^1) but adaptations had to be made for static thrust, which is a special case (efficiency = zero!), and further adaptations were needed to account for prop shape, prop foil, disk load in terms of power per square foot. Also altitude density changes needed to be put in. The end result is that there is a quite fixed relationship between power and thrust, as Dick found out in his experiments. This however is only valid at zero forward speed.