Ultra Stupid Funjet!!!

[Gabe]

Here's the paint job - far from perfect, but she'll be waaaaaay easier to see in the sky compared to all white:

[19000rpm]

Like the saying goes, "You can't fly if you can't see it."

[akent]

Looks good, Gabe!
I actually just put some paint on mine. It's drying now.

The ESC came in and it fits!

I hope to fire this baby up in a little while!
Kent

[akent]

Aug 8, 2010 6:51:06 GMT -6 19000rpm said:

So, which ESC did you decide on Kent?

Oops, sorry 19k. I missed this question.

I ordered a couple of different ones from HC.
This is the one that I installed. It's an 85 amp one that is good for 100 amps peak. Since I am going with 6s, I don't need the other massive one.
www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=10331

I haven't fired it up yet, but I did program it already. I bumped up the frequency to 16khz. This ESC comes with a BEC on-off switch! I removed that. It looks an awful lot like the Hobbywing!
Kent

[19000rpm]

Look forward to hearing how it works. It seemed to get mixed reviews. The price seems right and when I was viewing it a window opened offering it for $39 bucks.

[Gabe]

Whew man, she's way easier to see now. No visibility issues whatsoever. Making about 630 watts on the launch, and then 560 watts consistently at WOT. Pulling 34 amps and unloading to 27 amps. That's really a super low current for that many watts.

Doesn't feel like 100mph, but everyone is saying 450 - 500 watts will get you there. Maybe I'm spoiled by the fast Strykers I've been flying.

[akent]

Humm....
I'm running around 800 watts and going 110ish in my 'normal' Funjet...
Edit: Just remeasured with a fresh 4s and it's 850 watts that then settles down to 775 or so.

Well, we'll maybe be able to create a curve. I have the Stupid Funjet together. It's running between 1.9kw and 2.0kw on 6s at somewhere close to 40k rpm. Neither of my tachs will work at these rpms!!!
I'm running an APC Speed 400 5.5x4.5 (the same as my 110mph Funjet). I'm going deaf from testing this thing!

I'll try to get a video of it spooling up.
Kent

[akent]

Aug 10, 2010 6:30:07 GMT -6 19000rpm said:

Look forward to hearing how it works. It seemed to get mixed reviews. The price seems right and when I was viewing it a window opened offering it for $39 bucks.

Yeah, I saw those reviews, too. I think some of the bad reviews might have been fairly old. The ones with dates seemed to be more favorable.

I am pleased with this one. I'm pulling 89 amps peak with a fresh 6s, so it's holding up. This settles to around 84-85 amps after a few seconds. I have simulated a couple of flights on the bench (in my lap!) so far.
The battery and the wires get warm, but the ESC stays cool so far.

This motor is not even breaking a sweat! I kept it at WOT for about 15 seconds (an eternity!) and the motor was hardly warm. The 12 gauge battery wires were very warm as was the battery. Not hot, but very warm.
I don't know how this will hold up in the 100+ heat we've been having every day. I will take it easy for the first few flights, like I do with my other Funjet.

This thing sounds WICKED!
Kent

[19000rpm]

Sounds terrific.

High ambient temps can really effect the batteries. 100 is probably going to puff them, at the very least, if you're running WOT. The motor & ESC will probably be OK.

Good luck with the maiden

[Gabe]

Kent, what's the amp rating on the esc and motor?

Have u thought about running a bigger prop like a 6x4? You'll get a ton more thrust, but your amps will increase also.

[akent]

Aug 11, 2010 10:43:11 GMT -6 Gabe said:

Kent, what's the amp rating on the esc and motor?

Have u thought about running a bigger prop like a 6x4? You'll get a ton more thrust, but your amps will increase also.

The ESC is rated at 85 amps continuous, 100 amps peak (10 seconds).

The motor is the Typhoon 500 heli motor, so the power listed in the ad at HC is misleading. These are designed for 6s and high powered 3d heli flying.

The KV is too high for a bigger prop with this ESC. I do think I'm going to get the Ice 120 or 150 one of these days though! You should feel the push from a 6.5x5 pylon racer prop!!! It is HUGE!

I will maiden this one tomorrow!
Kent

[19000rpm]

Good luck with the maiden. I'll keep my ears tuned for a sonic boom.

[akent]

Well, I flew the thing through two batteries!

It's stupid fast all right! Really stupid. Guesses at the field (when I could stay in the throttle for more than a second or so) was 150 to 180!! It couldn't be 180, but it sure gets REALLY small REALLY quickly!
One thing for sure, ALL EYES were on it when it flew! It literally screams. And it's LOUD.

I found a speed where you completely lose control of the thing. No elevator or elevon input does anything at all. And it's torque rolling at the same time, but it's straight. That is scary.
After this happened and I let off the throttle, it did not come out of it until it slowed down considerably, which was a couple of seconds that felt like an eternity. This was way over 110mph, as my other one does nothing like that. My 110mph one seems like a slow flyer now!

My theory is that the foam is 'twisting' back by the motor, that the elevons are nowhere near rigid enough and that the servos are too weak. I'm running HS-65HB's on this. Also the elevon control lines are too small and are flexing.
This thing needs beefing up. I don't see how they are running 140+ on a stock airframe at RC Foam Fighters. They did show fiberglassing around the motor area, but that's all I remember seeing for mods.
Also, the motor flexed enough to dig into the foam a little in the back!! That's some SERIOUS torque! I can't bend it like that by hand.

I have no idea how fast this thing is, but it's just ludicrous! I love it! Most passes (after the first scary one) were made getting it nice and level and 50-75 feet up. I would give it a touch of right to counteract the initial torque some and nail it. Most passes were about 1 second into the throttle before it was too far away and out of control.

I will be beefing this up a LOT.

The thing is really really really really really really fast!

Muah hah hah, as Gabe would say!!!

And like an idiot, I didn't get any videos. Ugh. I didn't even think about that until I was driving home.. And I did have the cameras there. Bummer. It's hard to think about that when your adrenaline is pumping!

Kent

[akent]

Oh, and what's really bizarre to me is that the battery was the only thing on the warm to hot side. It did not puff, I think because I didn't have runs more than a second or two. But it was no warmer than any other battery I ran today!

The motor and ESC were not hot at all! Even though it was 103F today! I mean they were very warm, but you could touch them easily.

I really think this motor can take a LOT more power! (what did Kent just say?)
Kent

[19000rpm]

Really neat. Surprised the battery wasn't hot, but that's a tribute to your set up and throttle management.

Hope you get some video and a doppler next time out. I might have forgotten how to get home with that much excitement.