MVVS 58 vs DA 50 Vs ZDZ 80
04-05-2007, 03:54 PM
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RE: MVVS 58 vs DA 50 Vs ZDZ 80
ORIGINAL: NikolayTT
Thanks BTerry,
I just wander why then
in his reply on 4/4/2007 (here above) Pe Reivers wrote 'forget the advertized horse numbers',
did I misunderstand something ?
Anyway, the table is really great and the best I have so far; sincere thanks to Pe Reivers
for ptoviding it - it will save me a lot of time for tests !!!
Thanks BTerry,
I just wander why then
in his reply on 4/4/2007 (here above) Pe Reivers wrote 'forget the advertized horse numbers',
did I misunderstand something ?
Anyway, the table is really great and the best I have so far; sincere thanks to Pe Reivers
for ptoviding it - it will save me a lot of time for tests !!!
Many engines with high peak horsepower may exhibit a weak low or middle range, and only kick out the power at high RPM. Accelerating a propeller requires torque, and as such we “feel” the torque. Gas engine manufacturers are not as bad as nitro engine manufacturers in this regard.
Many nitro manufacturers will quote a high horsepower rating for an engine that is measured at a very high RPM with a small propeller. For instance, why should I care how much horsepower a .90-sized engine can develop at 15,000 rpm, with a low thrust output and high flight speed, when I will prop the engine for 11,000 rpm with significantly higher thrust and a speed matched to the airframe?
You are on the right track now. The spreadsheet will help too. I find I can estimate the performance of a particular prop on my planes by comparing the thrust, speed, and power required to turn the different props. I just match the RPM, and power required to turn a specific prop at that RPM, and then tweak the other variables a bit -- adjust diameter, pitch, prop constant, etc., one variable at a time.
Brett
04-05-2007, 04:05 PM
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RE: MVVS 58 vs DA 50 Vs ZDZ 80
Back to the original question; The Comp Arf 2.3m Extra is a "tweener" size. It is right between a 50cc plane and an 80cc plane. Any of the three engines listed (DA 50, MVVS/Evolution 58, or ZDZ 80) will fly it well. I know somebody with that plane on a DA 50, and it flies nicely, and he thinks the power is just fine. He flies "energy-retention" routines, and the power is very close to scale, i.e. it can do anything a full-size Extra can do. It is very smooth and controlled, and weighs around 19# or so.
Most people would rather go with more power to experience the explosive vertical penetration. The MVVS 58 would be perfect as far as power goes. The ZDZ80 will weigh the same as the MVVS, but power is greater and will require more throttle control to keep it under control and below VNE.
The ZDZ has very smooth throttling characteristics, and in the low to mid range the engine almost feels like an electric. In fact, on a cannister, sometimes I need to throttle up to determine if the engine is running. It makes less apparent noise than a .60-sized nitro engine.
I have no experience with the MVVS engine but they have a very advanced design, and the machining is very good. I hear good things about them.
Most people would rather go with more power to experience the explosive vertical penetration. The MVVS 58 would be perfect as far as power goes. The ZDZ80 will weigh the same as the MVVS, but power is greater and will require more throttle control to keep it under control and below VNE.
The ZDZ has very smooth throttling characteristics, and in the low to mid range the engine almost feels like an electric. In fact, on a cannister, sometimes I need to throttle up to determine if the engine is running. It makes less apparent noise than a .60-sized nitro engine.
I have no experience with the MVVS engine but they have a very advanced design, and the machining is very good. I hear good things about them.
04-05-2007, 04:18 PM
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RE: MVVS 58 vs DA 50 Vs ZDZ 80
Dick,
The 24x10 Mejzlik comes in one flavour only. Not so the 26x10N and the 26x10.
In their documentation, MVVS mentions the 26x10 and not the Narrow bladed 26x10N.
@ nikolay and Bterry,
Advertising is a way to play the mood of a potential customer. There are very few engine producers that actually publish field setup horsepowers. That is why I said, forget HP publications. MVVS and Zenoah are exceptions. They have published power curves, or allowed their dealers to publish them. MVVS in addition makes a statement about publishing propellor test data, using Mejzlik propellers.
Because these are tested on a sophisticated dyno, I can use these Mejzlik's as benchmarks to "calibrate" my calculator.
A funny coincidence:
The other day a university called about a solar boat using a Mejzlik prop as ship's screw. By raising the barometric pressure in my calculator to 880,000 mBars, the density was like water, and hey presto, the prop behaviour in water could be predicted in terms of thrust and absorbed horsepower. This was done with utter disregard of eventual dynamic viscosity differences, but who cares! Main objective was looking at the design ball park and finding a commercial available prop to match the solar power and motor/gearbox combo.
The 24x10 Mejzlik comes in one flavour only. Not so the 26x10N and the 26x10.
In their documentation, MVVS mentions the 26x10 and not the Narrow bladed 26x10N.
@ nikolay and Bterry,
Advertising is a way to play the mood of a potential customer. There are very few engine producers that actually publish field setup horsepowers. That is why I said, forget HP publications. MVVS and Zenoah are exceptions. They have published power curves, or allowed their dealers to publish them. MVVS in addition makes a statement about publishing propellor test data, using Mejzlik propellers.
Because these are tested on a sophisticated dyno, I can use these Mejzlik's as benchmarks to "calibrate" my calculator.
A funny coincidence:
The other day a university called about a solar boat using a Mejzlik prop as ship's screw. By raising the barometric pressure in my calculator to 880,000 mBars, the density was like water, and hey presto, the prop behaviour in water could be predicted in terms of thrust and absorbed horsepower. This was done with utter disregard of eventual dynamic viscosity differences, but who cares! Main objective was looking at the design ball park and finding a commercial available prop to match the solar power and motor/gearbox combo.
04-15-2007, 01:14 PM
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RE: MVVS 58 vs DA 50 Vs ZDZ 80
ORIGINAL: pe reivers
The 58 reportedly and repeatedly runs 6100 - 6200 on a 26x10 Mejzlik prop and 3204 canister. This muffler has sacrificed top end power for a wide powerband response. Power and torque curves can be downloaded from my web pages if anyone cares to look at them instead of quoting the lack of them.
MVVS never had this engine running with a tuned pipe, but I did, and got 7500-7800 rpm with a 2-blade Mejzlik 24x10 and KS50 pipe, not tuned for best power yet. This equates to nearly 9 HP. This test earned me some grave looks from MVVS who never designed the engine for this kind of rpm.
The 58 reportedly and repeatedly runs 6100 - 6200 on a 26x10 Mejzlik prop and 3204 canister. This muffler has sacrificed top end power for a wide powerband response. Power and torque curves can be downloaded from my web pages if anyone cares to look at them instead of quoting the lack of them.
MVVS never had this engine running with a tuned pipe, but I did, and got 7500-7800 rpm with a 2-blade Mejzlik 24x10 and KS50 pipe, not tuned for best power yet. This equates to nearly 9 HP. This test earned me some grave looks from MVVS who never designed the engine for this kind of rpm.
Pe, I have looked at your web site at your power & torque curves, can you please explain the difference between MTW 110 and the KS 88 VS-4 R vs the KS 50 reso pipe or the KS 1060-4 B.
Mike
04-15-2007, 05:05 PM
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RE: MVVS 58 vs DA 50 Vs ZDZ 80
Pe, I have looked at your web site at your power & torque curves, can you please explain the difference between MTW 110 and the KS 88 VS-4 R vs the KS 50 reso pipe or the KS 1060-4 B.
The published power curves are taken from the MVVS dyno. They used the 3204 canister for the tests.
Many German pilots use the MTW TD75 or TD75K, because package room requirements are smaller than the 3204. The TD mufflers however need a longer header than the MVVS canister.
