Lepton build-up thread

[MadMan]

Exactly as I calculated it - but I can use the Jazz40 A speed controller and it is just as efficient running a 50% flat line curve as a 90% flat line one. Keeps us all in a much more affordable ESC envelope. Now all I have to do is find a 5S pack that will fit! Any ideas on that?

[mudbogger2]

I still think you may be lower tham 50% to keep it around 2800. Plus I think you will be pushing the 40 amp esc even on 5S.

I am at 77% on my 4S with a 668 KV motor and at 2700 rpm on 26 tooth pinion.

I think the 5S 3700 or 3300 mah evo packs will fit in but I am not positive.

I do think a 5S setup is going to be ideal on this heli though. More pinion choices woud really be nice about now.

[MadMan]

Thanks Jon. I think the math would work out, if all was linear, to 2700/4000=68% no? The goal is to use the 40A ESC - but not a requirement. If the motor was 1000 kev (approx) and pulled 32 A continous and 48 A 30 sec max burst, the Jazz40 specs say it would work - but it would also depend on what headspeed I was trying to pull as I've found out by having a Medusa 3400 kev motor kick out the Jazz 40 with too much headspeed (and that motor says it bursts to only 35A - but I think it's a fib).

Worth a shot though not to have to step up to that Jazz55!

[mudbogger2]

I have some more flight reports on my 4S setup.

Started pushing it a bit. no pauses between manuvers. 2700 rpm headspeed
86f outside.
5 min flight- 160f motor - 119f batt- 101 ESC- 2532 mah used
6 min flight- 170f motor- 128f batt- 101 ESC - 3275mah used

I also did a hovering only flight at 2800 rpm(yeah it's high for hovering) and got 10 minutes before power dropped off. Put 4280mah back in the pack afterwards too :shock:.

I really think 5S will help lower temps with the lower amp draw. These temps I am getting are starting to concern me.

[Finless]

Yea the temps I get are a TAD higher than I like on the motor. The batts are no problem but the motor at 160 concerns me. My curves are lowered to 90 at max throttle for RPM so I think a slightly smaller pinion would help too.

Bob

[Stuka]

I figured Hirobo knew what they were doing when they put a fan on their motor. I searched but I couldn't find a fan for the Hyperion. I don't think they make one. While I was waiting for my preordered Lepton to arrive, I decided to CNC a fan based on Hacker's outrunner fan. (http://www.espritmodel.com/images/accesories/a30_fan.jpg)

http://www.runryder.com/helicopter/gallery/5564/hyperion_fan_1.jpg
http://www.runryder.com/helicopter/gallery/5564/hyperion_fan_2.jpg

I'm still waiting on a new yoke on the slow boat from Japan so I'm not in the air yet and I'll only be running 3S. Do either of you want to try beta testing the fan and comparing the temps with and without?

I'm also going to make some proper tail pushrod supports. One isn't enough. I think it needs two to keep the pushrod from buckling. Probably my only gripe about the kit.

Chris

[Finless]

Intersting fan but without a housing around it and vertical fins I dont see how it will actually move any air? It looks designed like a nitro fan but this type of design requires a offset shroud to actiually move air doesnt it? Or am I missing something?

Bob

[TMoore]

The fan looks like the one that is on Jeff's Lepton. I saw it fly at the Grand Event. The motor on Jeff's is probably a Hyperion but with a Hirobo label. I was thinking of CNC'ing one of those myself.

TM

[Stuka]

The housing is the can of the motor itself. The fan is centrifugal and blows radially in all directions. This is the exhaust air. The intake air comes in from the top of the motor, flows around the coils, and gets sucked out the holes in the bottom of the motor where the fan is mounted.

Chris

[Finless]

Stuka,

Hmmmmm I have to question this. I aint no aerodynamics or fluid dynamics engineer but I do understand a bit about Bernoulli’s principle and maybe I am just missing it.

I have seen a fan or "impeller" like that used in many applications but in every application the fan or impeller is offset in a shroud that allows it to create a low pressure area (close to the shroud) and a high pressure area (farther from the shroud). This is the ONLY way this kind of vertical fin fan or impeller works. At least that is how I understand it.

You certainly don’t see Nitro engines with this vertical fin type fan WITHOUT being offset in a shroud! I am into boating and this type of "impeller" is used all the time to pump water, and again it doesn’t do anything without being in an offset shroud.

Now I do understand that the simple fact that this thing is spinning below the motor WILL cause a SMALL low pressure area, it has got to be the most inefficient way to do it? Surely not worth the trade off of having the motor work to spin it.

I am not trying to argue and say it doesn’t work! I am simply not understanding the concept so am I missing something?


The housing is the can of the motor itself.


How is that so? To move air you MUST create a low or high pressure area. I don’t see how the motor can is providing that? The fins are vertical and as I said above I agree the shear fact that it is spinning will cause a low pressure area but it will be small in my opinion... Again am I missing something fundamental here?

Bob

[Stuka]

No, I don't think you are missing anything. On a nitro, cold air enters the fan axially and exits radially. Then the shroud guides the cold air over the cylinder. Then hot air exits the shroud. With this fan, cold air enters the cooling holes toward the top of the motor. The air flows through the inside of the motor and heats up. Hot air enters the fan axially and is ejected radially in all directions. All the shroud is doing on a nitro is directing the outflow from the fan into a useful direction. The fan still pumps the same volume of air whether or not the shroud is in place.

I was able to spool up to a low rpm without the main rotor and I could feel the fan moving the air. Now I just need to find out how effective it is at bringing the motor temp down.

I think I had a Dremel with a cooling fan that worked this way too.

Chris

[TMoore]

The fan looks nice. If my motor runs hot I might make one out of aluminum.

TM

[Finless]

Well if the fan works and does cool the motor I would be interested in one Terry. If you make one how about making 2 and selling me one? If so how much?

My motor runs at 160 and I would really like to see it in the 130's.

Bob

[TMoore]

Bob, if I make one I will make two. I'm just not sure what I'll make it out of. I'll just have to check my stock of material here at the house.

I think that Stuka is on to something. I'm wondering if there is a commercially available unit for this motor. It would be a lot easier than making one.

TM

[Finless]

Agreed. I was looking at it myself and because there is no extra shaft coming out of the bottom of the motor the thing has to be attached to the outrunner can where it grubs screws hold it to the shaft. Of course doing it this way brings balance concerns no?

My understanding is this is the same motor used by Hirobo but they must have got the manufacturer to make some changes to the outrunner can?

Bob

[Gscott]

There is one available for the Hacker. I wonder if it would fit the Hyperion as well.

[Stuka]

No, the Hacker has 4 mounting holes and 4 sets of fins. The Hyperion only has 3. The space between the fins has to line up with the holes in the bottom of the motor.

Chris

[buster1]

Do you guys think running the Hyperion without a fan over time is going to be an issue?
Bob, we have the same set up and your motor is reaching 160 - do you think this is something to be concerned about??

[mudbogger2]

I don't think 160 is too bad. 170+ is getting excessive. I know the larger hackers used in the ION had a temp limit of 180f max.

[misskimo]

hey Jon , I see you got it running from the last time I seen you 3 weeks ago , up to 170 on the can is a good start , the inside will be much hotter though , what motor are you useing ?

[Finless]

160 is within SPEC so I am told but like anything you push to the edge of spec it's not going to alst as long in my opnion. Bt if I can get 100 good flights out of a $99 motor then I will be happy.

Again I think a SLIGHLTY smaller pinion will help the temps. I had to drop my curves to 90 at the high points of throttle. It would be better to be up to 100 and a biut flatter curve, thus using the ESC and motor more effeciently. When I had it at 100 I was hitting head speeds of just over 3000!!!!! I would run that but with such a new heli I am not sure it can take it.

Bob

[mudbogger2]

Hey Tony. I am using a Hyperion 3025-12 motor on mine. I have dropped the headspeed back to around 2600 and will do some testing there and see if the temps come down.
I think the 24 tooth and near 100% on this motor would be around 2600 for a little better efficency.

Just wanted to get some thorough testing on the 4S before I try 5S. :twisted:

[Stuka]

Just finished some delrin tail rotor pushrod guides. I made 4 sets with different inside diameters to get the press fit just right. No additional clamping fastener to make it even more tail heavy. If I get a couple people interested, I'll run a batch to sell. Here are a few pics.

http://www.helifreak.com/album_mod/upload/4d7c35d466c2420147c7ed0bccbdb104.jpg
http://www.helifreak.com/album_mod/upload/665b778120a6fecd103d1569d619363b.jpg
http://www.helifreak.com/album_mod/upload/a2b1a4da7fd23b27e51d2a3cbbfecc90.jpg

If anyone wants a pair, let me know.

Chris

[Finless]

Stuka.... NICE! Yes I will take a set!

Bob

[MadMan]

Count me in for a set as well. Please note that as they really looked good.