Okay, I don't know how I missed this project.

First of all, great idea! I have that same ducted fan unit in a completely different project of mine.

Second, the manufacturer may say that the fan unit can take more than 27,000 RPM. Don't pass 30,000 RPM. I was using a Feigao 12XL and 24v lead acid through a Phoenix-60. Here are some numbers after the fan was running for a minute or two:
-21v
-110amps
~2300 watts (3HP)
-~25,000 RPM
And yes, the Phoenix-60 with some copper heatsinks and 6 extra capacitors was pushing 110amps. Unfortunately my watt meter couldn't, and was smoking/melting a bit.

I've already broken two of the fan blades while keeping the fan around 25,000 RPM tops, without a load on the fan (just spinning the fan in open air). That said, my setup is a bit different, so that could have cause the blades to break, or it might not have.

Without modifying the unit, it can only accept motors with a diameter up to about 37mm. That means Neu 15xx series motors won't fit, unless you cut the shrouding around the motor.

If you don't have the ESC already, look into the OEMRC Sentilon 100amp 12s airplane ESC:
https://www.unitedhobbies.com/UNITED...idProduct=4691
https://www.unitedhobbies.com/UNITED...idProduct=2169

And let me say it again, don't spin the unit too much past 30k RPM.

Thanks everyone. Metalman I didn't see that bit about 30K RPM anywhere in the instructions for the fan. Thanks for mentioning it. It is good to know that the Lehner can take the beating without kerploding, but I guess I have to find another fan. I really want to stick with a single fan setup to save the extra weight. I need a MINIMUM 9# of thrust for the project because I'm aiming for at least a 1:1 thrust-to-weight ratio. Also, I want to stay with the 90mm size fan, or smaller if such a thing exists.

Please, no more links to those R/C turbines. I know they're awesome but unless you want to donate one then they are out of the question.

Have you thought about the carbon fiber EDF units? I'm pretty sure that is what those 200MPH+ EDF planes use.

Oh, CF units- I've seen a retailer of those somewhere...I'll be back in 10.

It's not in the instructions, I think of it as more of a mechanical limit. An older guy at the LHS I work at is a retired aerospace engineer, and big RC airplane afficionado, said that the fan unit shouldn't be used past maybe 15,000 RPM. But asking 9lbs of thrust out of it is most likely too much.

I was gonna look at the CF fan units. But DAAAAAAAAAAAAMN they are expensive! :surprised:
I think I'll build it with the DF90 for now. OTOH I could use a Feigao FTTB since it only has to run at 30K RPM. That should allow plenty of driving practice, too.

I wonder if I can still do donuts with it?.....:whistle:

Why is it when you need to find something you looked at only a week before hand you just cant seem to find it? Never mind- they are hideously expensive yeah. Motor wise, the Hv motors run brilliantly well at upto about 40-50K, then they tend to get rather warm, especially given a heavy load.

I think for now* I'll run 5s LiPo and a 10XL. That will leave room for upgrades, too. We all know just driving our cars/trucks "as is" gets boring after a while.

*when I have money to buy the stuff, and get around to putting it all together...

is the fan going to be fixed mounted or are you going to make it steerable left and right, if you made the fan push you in the same direction the front wheels were turning then the car will not push so bad into turns.

A steerable mount would be slick, but would require a sturdy pivot for sure. And a high torque servo, or some sort of torque multiplying linkage. You could also set the servo up on the third channel and mix it with the steering channel.

The fan will remain fixed for now. It will have a 2 degree downward angle to add downforce while accelerating.

Seriously. That would be SO awesome. :yes:

any videos of this moving yet?....

Sadly no. I just don't have the cash right now to buy what I need to finish it. I'm simultaneously working on 4 other projects as well. That's how I work - I start things and go as far as I can until I either run out of ideas or money or both. As ideas and money trickle in I make progress on each of my projects. Call it P-ADD.

I did see this though. http://www.airpowernet.com/twe/produ...roducts_id=530

Nice EDF, I see it's good to 45K RPM, that should give some breathing room for a HV setup... 120mm is realy big though.

I had the AP 90 mm and I ran it over 45K without any problems.. just make sure to balance it.

Sorry guys. This project has been scrapped. The Ultra can be found here.