Daniel Z

I have reviewing some info about engines to search where is the best Power to weight ratio, an issue highly apreciated for the 3d flyer and based on the official specs I have found this:

Daniel Z

Ok, there must be some things obiously wrong.. for example I cannot believe a 46fx to be more powerfull than a YS63

but... this are the numbers (not my fault)

what do you think?...

Daniel Z

HP`s

MetallicaJunkie

wow i never new the 55 ax was that close to the power of a saito 100

asmund

It isn`t.
The AX 55 is rated at 1.75 hp at 16000 rpm. How many actually run it at that rpm, it would take a toothpick propeller to get to that rpm.

The fourstrokes are usually rated at much more realistic rpm and opposite to the twostrokes can actually deliver what is claimed.

Ever tried to fill in test data into Pe Reivers prop test hp calculator?? The twostrokes never come close to the claimed hp whereas the fourstrokes actually do


http://mvvs.nl/prop-power-calculator.xls

MIXMASTER

My Feedback: (15)

HP,RPM,Torque-doesnt mean much to me, its thrust/weight thats all important for 3-D, hovering most. If you can get real finished weight numbers, then all you need to know is thrust of the engine, in general you need at least one size up from recommended engine.
If I built a .40 size I used a .50-.60 engine, 60 sizeusually a .90 and if .90 sizea 1.20 engine. Nirvana starts at 1.5:1 & higher,then hovers are better and less work for the engine. For some reason, 30% gas planes and larger(the best of them anyway)work well with the recommended engine if you stay with the top choices. I get great thrust/weight with all my 30% gassers & DA50's. When I was flying only glow, had a harder time getting the best combo, always wanting more "thrust". The best glow engine/plane combo I ever had for hovering was .90 Fusion/OS 1.20AX-plane weight was around 7 lbs, engine thrust was probably 13lbs or more-hovers were getting 5 minutes long, almost boring!!! I even had a few 1.60glow/40cc gas planes, this size is not where its at IMO, gas engine too heavy, glow not enough power, sucks too much fuel!!!

Daniel Z

Asmund,

Thanks for the data sheet using it I estimate a 46ax with a apc 12.25x3.75 @12000 rpms to be in the 1,2Hp values, and that sounds much more like reality, will try to correct the values and make the graphs again, so we can have something real to compare engines

rmenke

My Feedback: (13)

Daniel Z:

At some point in this hobby you learn to rely only on yourself. Motor and engine manufacturers numbers are usually bogus. Recently bought a 750 watt rated motor, where in fact with the recommended prop and battery, it produced 450 watts. Fore some time I have built a motor/engine test stand on a sliding platform and connected to a digital fish scale. If I need a engine/motor capable of producilng 1.5 to 2 to 1 power to weight I buy the engine recommended by the manufacturer and test it for reasonable compliance. If it does not cut it, several have not, I send it back. Have returned two electrics and one glow and received slightly larger motors/engines without a lot of hastle. Think our RCU forums can make or break a product not as advertised, so manufactdrer/retailer is a little more willing to back up their claims. The 3D hobby shop and Horizon get the nod for good business practices so far. l want to give them the credit due here. If a retailer refuses to back up a product sale to work as advertised and intended, go somewhere else who will. There are people out there who do care about the quality of what they sell as a simple matter of good business practices. We should all partonize them. ENJOY

Wings-RCU

My Feedback: (2)

Daniel,
All of those horse power numbers are pretty much useless. They really tell you nothing about the 3D performance you can expect. I have owned almost all of these engines and had most of them on 3D profiles. Believe me the 46Fx, 55ax, and YS 63 are not in the same class as a Saito 100 when it come to 3D. The 100 will swing a much bigger prop giving you better an much more instant thrust. I found the Saito .72 better than the 46 or 55ax for 3D although the 55ax may have as much top end power. The .82 is better yet. In two strokes, the MVVS .49 or the Webra 50/55 seem to work better for me because of the instant throttle response.

Daniel Z

yep I agree, 2strokes and 4 strokes have their own abilities, but if we use real life numbers with real props and rpms, we can get the HPs and then REAL power to weight ratios... I have updated them, added some engines and as I can see It is getting closer to the real thing, check it...

asmund

I use both two and fourstrokes, never can seem to make up my mind which I like the most. After I got really comfortable at hovering I do not need brute power anymore to rocket out of troubble. My last Katana 40 profile had a ASP .61 fs and I could hover it down on the deck till the tank was empty, pullout was slow though

My current katana profile 70 I flew with the YS 110 and then switched to a tuned FX .91 and I enjoy that one as much as the YS 110. What`s best?? I really don`t know

Wings-RCU

My Feedback: (2)

Daniel,
REAL power to weight doesn't matter much, and doesn't necessarily give you an indication of 3D performance. THRUST to weight will give you a much better indication.

Example using a thrust and horse power calculator with the same pitch prop to keep it fair.

a four stroke turning a 16x6 at 9000 rpm results in 1.72hp

a two stroke turning a 12x 6 at 13800 rpm results in 2.33 hp

Despite having having significantly less horse power, The four stroke turning a 16 x 6 will give you almost 2 lbs more thrust. You will be able to hover a heaver airplane and have better pull out even though you have less horse power.

martin_solo

The Enya 61CX is as light as a OS 46AX

Have any one tried one for 3D ?

Martin

Blade-breaker

My Feedback: (4)

I also like the fast throttle response of the 4s engines, but I have a 55AX on a Mojo 40 and the throttle response is super. It took about 2 gallons to become very good but no complaints now!!! I have a Saito 100 on a MoAss that is waiting for decent weather to maiden. Cant wait!!

I believe either a 2S or a 4S can perform very good at 3D if tuned properly.

asmund

Exactly

Daniel Z

i have a YS110, a YS63 and a 46FX, And belive me, the most reliable is the OLD ex pylon racer osfx! using tower muffler and 20% nitro it rules!

anyway, if it is better to compare thrust, it turn things more complex, because I don´t know if there is a way to calculate it from RPMs and props (thats the info I have benn collecting)

Update: Thrust calculations can be obtained from the same datasheet asmund post here.... lets see...

iflyrc12

My Feedback: (1)

i have a ys 63 and have had many 2 strokes i love 3D and would say the os 90fx on an apc15X4W is about equal to the ys63 on a apc 14X4W in thrust