I have used Graupner CAM props - 6x6 and 7x7 and also Aeronaut makes a good 7x7 here-
http://www.hobby-lobby.com/7x7_elect...k_778_prd1.htm

HL bailed on Graupner, but you can order them from anywhere with the internet at your figertips! v-eastonline is the US dealer now. I odered a plane from them recently.

The antenna setup is correct. The rx will come with a mini disk with a pretty decent video on it. I even watched it and I don't usually bother with instructions

Originally Posted by tho98027

Plettis... they're in a league of their own.

I love your website/blog Jocke! I check it often. It's always fun to read your projects and articles. Keep up the good work man!

Thank you!


This is a 450g 8 pole mini beast, 1340kv 44mm diameter. Original its a power boat motor but this sample is adapted, it also has an aded internal fan, if you push it 70A or below the eff will be under 84-85% but if you push it to 90-100A+ you will hit 87% using 8-10s LiPo will be used in combination with CC ICE 160HV and Vapex 40C packs.

Mike - You can also use APC Sport (Nitro) Props. I have used them in many high performance "E" applications. They tend to pull less amps than even the high performance E props and they have very sturdy hubs and roots. Obviously anytime you exceed the limits put on the props by the guys who made them you are taking a risk...however, I have found that for liability purposes they pad those numbers.

If correct, one or more APC 7x10's have shown up at the German Speed Cup event and for sure they were turning between 25,000 and 30,000.

When this 36mm motor gets here will be working my way up through the APC Sports in the arsenal...you will find that there is a real HOLE in the market for smaller 6.5 to 7.5 (High Pitch) speed props...that incudes folders as well...I feel lucky to have that 7x13 custom folder from Marcus.

Hey jocke what is that motor going in?

I NEEED the motor that can turn a 7x10 past its failure point

Or maybe Mike's talking about carbon folder props that can run 30K...

I've heard a couple reports from experienced high power dudes of the Aeronaut 7" cam carbon props failing at 25,000 RPM. I ran one at 28K before I knew this. got lucky it seems, but won't do it again.

It makes no sense to run a 7x10 over 31K because of the tips going supersonic at speed!
That takes about 4KW!
The APC7x10 sport will hold together at 30K rpm! Speed around 250mph!
Thats why the speed cup guys are now running 7x13 carbon folders.

Grtz René

Are there any non-folding props out there in the 7x11 to 7x14 or so range?
Seems that the folding isn't really necessary for speed cup type stuff.
And a solid hub would be able to handle more RPM.

Maybe I'm just scared of folders...

Things are changing with drivelines in that speed cup stuff...I have "little birdies" in Germany that have hinted about some new stuff in the works...new planes as well. Can't wait to see what happens this summer over there.

Don't be afraid of folders Murdo - they are the way of the future

Wish I could fly over to the Speed Cup...just remembered that 800 dollar credit I have with Delta!

Hi murdo

There are no commercially available 7"props with more than 10"pitch.
The speed cup guys make them from their own moulds.
You have have to be on the incrowd to get at them.

Grtz René

Originally Posted by Steve C

I have used Graupner CAM props - 6x6 and 7x7 and also Aeronaut makes a good 7x7 here-
http://www.hobby-lobby.com/7x7_elect...k_778_prd1.htm

HL bailed on Graupner, but you can order them from anywhere with the internet at your figertips! v-eastonline is the US dealer now. I odered a plane from them recently.

The antenna setup is correct. The rx will come with a mini disk with a pretty decent video on it. I even watched it and I don't usually bother with instructions

Thanks I just picked one up to add it to my testing.

According to APC there 7in electric and folding props are only good for 21k

I have one of those 7x7 aeranauts somewhere, I remember working out the max rated rpm was only like 14k! so threw it in the bits box...

A big thing to remember with tip speeds, is its not only a rotational speed that effects it. The blade is also moving forward at the planes speed, which pushes the tip speeds up even higher (think of it as a helical tip speed). I was knocking on 49krpm with a 4.75x4.75, which with a 195mph forward airspeed (and no longer accelerating - Big WALL of noise!) resulted in a .99 mach tipspeed! Chopping the prop to a 4.2" and reshaping the tips resulted in MUCH better peformance (197mph and still accelerating strongly is the best result so far) as the tip speed dropped to .9, it also sounded a hell of a lot more refined

As you push tip speed higher and higher, the scimitar shaped tips of graupner camspeeds and the likes actually performe worse than regular tips.


http://www.supercoolprops.com/articles/transonic.php <- great info on high performance props on this site.




My Baby Monster -

Been alot of good information on these posts. Which gets me down this road to go really fast with a prop.

Ok, so to get close to 250 mph, using a APC 7 X 10 prop, keeping rpms below 31K, what motor would you use and with how many cells that might "live a few days at the field?"

Thats my question I used to search for motors. I found several 39.8 mm motors, all had long cases, which could use 5 cells, spin the 7 x 10 around 30K rpm and keeping the tip sub sonic.

Your ideas or thoughts on which motor and cells you might choose for that prop combo?

Originally Posted by jackosmeister

I have one of those 7x7 aeranauts somewhere, I remember working out the max rated rpm was only like 14k! so threw it in the bits box...

I wish you posted sooner that was a wast of $18

Is that a Mega 16/40/1 hiding under the hood Jacko? I'll bet that little beast is a hoot to fly!

Pilot - as soon as more data (real data) starts to come in I am going to try and consolidate it. The numbers Murdo posted back on page #2 are a wealth of information if you know how to read between the lines. All those inrunners are 36mm but they are different in KV and can length. As more data rolls in hopefully you will see a combination that you like.

But...as we all know we are badly limited by PROPS! We are going to have to start making them over here on this side of the pond like the German guys do over there. If anyone has any spare molds laying around I have the plastic to purchase them!

Mike is going to test a big ARC that he has and I have a 650 Typoon on the way that I am gonna squeeze hard with the APC's and a 7x13 folder.

High pitch props.

The speedcup guys started by repitching APC 7x10 props, and pulling moulds from them.
They made carbon copy's of these repitched props. Never try to fly a repitched prop at these power levels!

Grtz René