Originally Posted by DeadstickDuck

Hey, since I'm looking for 17x13 blades and I have 17x18 and they have to be used with the +7° spinner...hummm, what if I use those blades on the +0° spinner??????
.

Danger


Dont do it!!!!


Its not about folding well, it may really get dangerous ...

i tried to explane the context here:

https://www.rcgroups.com/forums/show...&postcount=676

Even worse if you would use a (for example ) 18x19 " F5B folder which was designed for a 7° yoke at a straight yoke .
You would reduce pitch at the inner side of the prop about 15% (just as example i did not calculate it) but you would turn pitch at the tips into negative!!
This means positive thrust at the inside and negative thust at the outside of the prop which would destroy it emmediately at high power!

Yello

Originally Posted by Mreyello

Danger


Dont do it!!!!


Its not about folding well, it may really get dangerous ...

i tried to explane the context here:

https://www.rcgroups.com/forums/show...&postcount=676

Yello

WOW!
I never considered this as a possibility.
Thank you Mreyello for the info.
...And so a noob learns that twisted & or offset hubs are not just for adding pitch or folding a prop flush with the fuse and must be considered as completely discreet systems.
Skies
Jay.
P.S. You don't pick mis-matched socks,don't pick mis-matched props & hubs.

Ya good to know. The RFM 0° spinner is still an offset spinner so the blades still fold. I am coming into this with a little more knowledge and foresight than most noobs but still ask before I try it lol....that's always the wise act. Better sound silly than loose an appendage and having you guys to bounce and share ideas with is the best part of these forums

SoaringUSA has the GM 17x13 blades in stock for $36 which is fine but for some reason I'm disliking the minimum $17 they want to charge to ship them,,,,, really? I think I'll take Yuri up on his nice offer to try his blades and I'll order some once I'm sold.

Originally Posted by Mreyello

Danger


Dont do it!!!!


Its not about folding well, it may really get dangerous ...

i tried to explane the context here:

https://www.rcgroups.com/forums/show...&postcount=676




Yello

So can a RFM (both prop spinner) 17x13 be used with a 5* yoke? I got both from soaring......or does it have to be 7*? Not sure why they didn't say anything about my combo....

I believe the big confusion is where and when the offset spinner is required. The larger and higher pitched props need the offset spinner to be able to fold properly and if you were to use one of those straight bar style yoke spinners, no folding nicely for you....

Also, the adding additional pitch (yes +0° is even counted, all the way up to +9 I've seen) is available to increase top end speed but low end get up and go will suffer since the prop will be cavitating the whole time and unless you're coming out of a high speed dive or maintaining high speeds, the prop will never be able to keep you in the power band and up at top speeds.

The RFM "Green" blades like the 17x18 are only actally 17x18 if you use them on the RFM +7° spinner as a set. I heard if you try to run the same blades on less than a +7 spinner you risk the blades failing...? So there must be some science involved we don't see readily apparent.

There are Green, Blue and Red blades and they all need a certain spinner with added +degs to get the rated pitch. The best way to go is just get GM spinner and blades.....as they become available.

That's my goal.

Darn it! These Roaringtop 6s3300mah 70C packs are just too big. They fit but like where are you going to put the battery/ESC cables Vern?.....ya, Houston we got ourselves a small problem.

I'll see if Roaringtop will take it back since I haven't done anything to it yet, still has the Deans connectors.

If I will make a plane with bath tub for battery compartment you guys will find a battery which won't fit
Yuri

I ordered some GM 17x13 blades from SoaringUSA since I see they fixed the $3 s&h lol...

I already got a 17x13 GM with spinner directly from Georgi....the RFM 17x13 and the 5* degree yoke are also new from soaring.....

So the question can the RFM be used with that yoke?......I understand what you said but I will wait and see if anybody has that answer....

I shot SoaringUSA an email to add a 0° spinner to my order. I asked Georgi about his 17x13 blades and he said not to use +deg yokes in offset spinners as the rated pitch on the set of blades is for 0° yokes.

The nice thing about the 17x13 is they are stalled below 13mph..... Which means there won't be any cavitation just nice acceleration.

Adding more pitch will make it act like a 17x14.65 (stalled below 25mph) on +5° and a 17x18.65 (stalled below 52mph) on +7° spinners.

I think the issue is if the blade is made to run on a +7° yoke and we purposely run it on a zero degree yoke it would fail and it's the end of the world as we know it.

My only issue...is I'm new at this, and i got this from soaring so if it's not made to run together, I'm not sure why they would sell it to me....without saying anything???

I'm glad you jumped in here to ask and share your thoughts so we can find out. There should be a reply in the morning from somebody at SoaringUSA.

17x13 RFM and 17x13 GM props are totally different
But they both made to be used ONLY ON "0"DEGREES YOKE
Yuri

Sorry for the late reply... had a buisy race weekend...

Duck,

I think I'll take Yuri up on his nice offer to try his blades

I really think you should take Yuris offer just for a try as i doubt the 17x13 is the right prop for an X-plus......i think it would get another shelfsitter...


Dansy..

So can a RFM (both prop spinner) 17x13 be used with a 5* yoke? I got both from soaring......or does it have to be 7*? Not sure why they didn't say anything about my combo....

As Yuri explained the RFM 17x13 is designed for 0° spinner twist and it has its pefect pitch distribution at a 0° spinner.
To adjust props with twisted hub to a specific application or ( for competition) to a given energy limit is quite common... usual range is up to 2°+/- of the props design base...speeders sometimes take a bit more...

You will have some minor disadvantages as the pitch distribution is not perfect but it might help to finetune a given drive.

For the 17x13 example a +2° hub seem to be an option as it might close the gap as there are no 17x15ish prop available and the pitch distribution may not be too far off.
A 5° or 7° twisted yoke dousnt make sense as it really destroys pitch distribution while there are plenty of proper designed high pitched 17" F5b props available....
Running props with over-or underpitched yokes at really high powerlevels requires some caution.....negative pitch appears more dangerous than positive pitch but once it gets close to the limit torsion forces might really get dangerous!!!

If I will make a plane with bath tub for battery compartment you guys will find a battery which won't fit

Maybe a 17x4 would get trendy again?


Yello

Thanks yello, I guess I will get a zero spinner assy for those blades.....it's not for the x-plus....