Just a quick note, folks... I just finished getting the new VessAero 26" props uploaded to the website at www.vessaero.com. Vess now has the 26" A & B pitch props in stock and ready to ship. They are:

VP-26A 26-inch Diameter, A-Series Pitch Prop - for use on 75-85cc powered aerobatic aircraft where more rpm or throttle repsonse is desired.

VP-26B 26-inch Diameter, A-Series Pitch Prop - baseline prop for 75-85cc engines on typical 33% aerobatic aircraft. Provides tremendous thrust for this class of airplane/engine!

They can be found in the shopping system at www.VessAero.com

Sweet!! Will have to pick up one!

R

I'd rather see the pitch or chord angle at the standardized 75% diameter instead of the silly A, B, or C. That at least would give some handhold as to what to expect. As a new kid on the block, Vess should know better than to be fuzzy. Data please. like blade angles and prop load factor at stationary, and at pitch speed.
Call me oldfashioned, but the design very much is like the old rubber powered handmades, with narrowed tips for noise reduction.

<sigh> Nevermind ... to reply to Pe is not even worth the effort.

Nice job rep'ing for Mejzlik, though ... you represent them well.

JS

On re-reading my post I was indeed a bit harsh and short of words, for which I apologise. I will try to be more specific.
I do need data in order to be able to compare any prop with known props. It's not only a matter of VESS, but all other prop manufacturers, who are very lacking in this respect. On some props I have very valid data, but from static measurements only with the prop acting as an air brake. Vess now even takes away that last bit of information by just stating their A,B and C-code. Even if the pitch is not linear over the blade diameter, there still is the more or less standard 75% diameter value. From there, you can correct the prop for effective thrust which is the result of juggling CAD data in the design process. CAD does not mean better, and final results very much depends on the knowledge of the prop builder, or the man behind the CAD station.
If now I want to get anywhere near comperative predictions on a VESS prop, I would need to buy one and measure it.
Testing and comparing still would be needed.
Look at http://www.mvvs.nl/prop-power-calculator.xls , and you will see why I want these data.

Pe,
Why dont you contact Robert Vess, he's pretty aproachable and I know he did a lot of flight testing with onboard telemetry etc
Maybe he will tell if its not a trade secret[

Andy

The only true way to tell one prop from another is to buy and fly. Prop calculators are ok if the information is entered from tested values and head to head comparisons but otherwise its mostly wishful thinking. Most every prop on the market will give within 80% of the performance of any other in the same range of size. But to see the addtional 10-15% ( if there is any) you have to bolt them on and put 'em in the air and decide what works best on your setup. I have tried Vess props on 4 of my setups and they performed very well on 3 of them, with the 4th preferring a Menz over the Vess.

On my GP CAP the DA100 will turn (static on the ground) a Xoar 26/10 @ 6800 plus, a Xoar 27/10 @6400, and a Vess 27A @6400. In the air the Vess outpulls both Xoars out of a hover/harrier, accelerates harder in a vertical than either Xoar, is faster than the 26/10 Xoar in an straight or upline but appears to be slightly slower at the top of an upline compared to the Xoar 27/10 and the Xoar 27/10 is faster in an horizontal straight line The Vess is louder at WOT than the Xoar 27/10 but not as loud as the 26/10. On top of that, the Vess gives me less wing rock in elevators and harriers than either Xoar. The Xoars are good props, If I break my Vess, i wouild fly the Xoar without any hesitation, the Vess just works a bit better for me on this plane

I wish calculators could tell me everything I just relayed here but they can't. They might help with determining a good prop from a bad prop but i don't think they tell you better from good, or best from better. Gotta fly them to decide.

take care
zonk

I agree, it is best to just try a Vess. I have been running the 26A prototype on a 3W 80 and ZDZ super 80 for sometime now. It just outpulls the others I tried hands down (mejzlik 26x10, PT 26x10, NX 26x10). The 26A loaded down the motors about 200-300 rpms compared to the PT and Mejzlik, but was night and day better. The best example is my friends AW 75cc yak with the super 80 (stock muffler). The airplane is a tank at 25.5lbs, and the 80 pulled it around with decent authority with the PT 26x10. Not ballistic by any means, but pretty darn good. We put the Vess 26A on it and the airplane came alive, it is now ballistic, just can't put into words how much harder it pulls. I don't have any affilliation with Vess, except he sent me some prototypes to try, so not trying to sell you anything but give honest feedback. The 26A for 75-85cc engines is THE PROP in my opinion.

Charles did you get to try the 26B?

I am trying to decide between the A and B on my Aviation Models 33% Yak after the engine finishes breaking in with NX-26-10. The plane will be very close to 23 lbs dry.

Thanks,

Richard

I have tried the 26A through D. I didnt like the C or D at all, way too much load. The 26B is a smidge better for imac, but not as good for 3D and does not spool up as fast as the A. The 26A performs awesome at 3D, but for IMAC type flying I found it just ok. For your yak (I had same setup, 80cs and can) I prefer the A for everything. The B might be better for something lighter, but most of our 33%s are realistically 22-24lbs. My friend has been running the 26A on his yak for sometime now, and everyone with 80cc engines has been trying to get it from him.

Thanks for the good info!

Richard

Is there a way to do that directly, or should I use the web pages?

Pe, here is Robert Vess' email [email protected]