F-86 pocket rocket

[akent]

I'm going to try to install the HK fan in the F86 tomorrow, if I can make the time. I am anxious to see what it makes the thing fly like.
I'll also take some current measurements. Not sure if I can rig up thrust measuring.
Kent

[19000rpm]

Be really cool if it works out to perform better than the stock unit...

BTW, Hobby Lobby still haven't shipped my stock motor replacement yet. The planes ready to go except for the motor. I'm going to try one of the Target Hobbies cloned 6110e's in it. I got those in 8 days from Hong Kong. The postage in Chinese dollars was $18.10.

[akent]

I just popped in the HK EDF this afternoon.

Here are the results with the stock 1600ma 3s:

Stock:
27A 300 watts

HK EDF:
30A 350 watts

This HK unit vibrates considerably more at lower rpms than the stock unit. It smooths out at high rpm. The top end rpms 'sound' about the same between both units.

The HK unit drops right in where the stock one goes, so it's great for a replacement if the stock one blows up.

I held the jet up by one wing and let the thrust bring the jet up. The HK unit feels about the same as stock. Neither has 1:1 or better, but they are both have good thrust. If the HK unit has more thrust, it's certainly not enough to write home about.

I'll fly the HK unit this weekend.

I think the stock unit on 4s might be cool!
Kent

[akent]

Here's a couple of pics:

[19000rpm]

As you likely know, the vibration means the fan is out of balance. It might come apart if you run it that way, Iv'e heard of more than a few that Xploded or ruin the motor bearings just like an out of balance prop would. I haven't ever balanced a fan, but I imagine it's a lot like balancing a prop.

Maybe the answer for the 86 is a slightly higher kV motor like a 5000. www.hobbypartz.com/75m90-ducted-2010-5000.html Look at the thrust on that baby. That might push the ESC a bit though. I'd put in a 40A.

4S would be interesting on the stock motor. Even a higher C three cell.

Look forward to hearing if there's any improvemnt in flight.

[akent]

Yep, obviously out of balance. But it's not that bad. I don't know how to balance these. They have very little mass! None of my balancers will hold one.

I wonder if that motor would fit? It's rated about the same power as the HK one that I measured, but that one has a higher KV. Humm...

4s would definitely push the ESC! The stock motor on 3s is close to 30 amps as it is....

I may try 4s to see if the EDF holds together. I have a spare 40a ESC laying around.

Oh, and in the above pictures, the EDF plastic came in blue. The pictures at HC show white plastic. They are the same unit, though.

[19000rpm]

Yeah, I've read about people balancing these EDf's, but I don't have a clue either about how to actually do it. If I'm going to keep this EDF thing going I should probably figure that out, though.


Your right, I don't think the motor will fit the fan assembly.

[19000rpm]

Check out the specs with the HL 64mm with Don's RC 4800kV set up. www.donsrc.com/cart/index.php?act=viewProd&productId=52

Here's don's build thread using the 4800kV and his balanced fan. 80mph. NOW, that's what I'm talking about! www.rcgroups.com/forums/showthread.php?t=1162134

Or, you can order the 4800kV with the standoff adapter and use the stock fan.

[19000rpm]

After talking to HL again I found out that my stock motor is backordered until the last week of Oct.

After doing some more searching on their website I found a 5000kV motor that fits in the stock fan. I called them and they are sending that one to me. Nice guys. www.hobby-lobby.com/brushless_outrunner_for_50_64mm_fans_5000kv_rc_motor_528703_prd1.htm

I'll go up to the 40A and 2200 25C. I'll fly it with the stock exhaust size and then try decreasing it, as per Don at Don's RC, for added speed. The initial thrust should be awesome with the stock exhaust diameter.

[19000rpm]

The 5000kV motor came and bolted right into the fan as advertised. I added the 40A ESC and decided to use my AR500 in it since it is the smallest Rx I have and the 2200 25C pretty much fills the rest of the equipment compartment.

On the bench it feels like it has twice the thrust of the old motor. I'm waiting for the fog to lift to fly it.


I added 3 pc.s of 3mm CF under the ply equipment board.

[19000rpm]

What a difference from the stock set up. Huge thrust for hand launching, and I'm guessing, about 75 mph top end. The 5K motor, 40A ESC and 2200 25C did the trick. The battery was pretty warm after the flight, so I might move up to a 30C.

I'll fly it again tomorrow and then tear it all down to see how everything is holding up.

So, Ken, what's up with the HK set up?

[akent]

HK setup is pretty much just like the stock fan, but more out of balance.

I was too scared to try 4s. I did spin it up on 4s and it felt like it was ready to explode. The out of balance was Ok at 3s WOT, but any more than that it was BAD.

Maybe once we can figure out how to balance these things, it might be ok, but until then, I ordered one of the 5kv motors like YOURS!!!! 20 bucks is not bad at all.

Hey, I really like your battery tray!

Awesome!
Thanks!
Kent

[19000rpm]

I think you're going to be amazed at the transformation, Kent.

I highly recommend the CF tubing under the battery tray. A 2200 is to much weight for a hard landing.

The next step would be narrowing the exhaust by 1/2" as per Don's set up. He says you'll lose a little thrust, but the top end goes to 80, or so, and his is a slightly lower 4900kV, and he says his unit is putting out 600watts.

4s with that set up would be insane...so, I know you'll do it.

[19000rpm]

Flew it again this AM and all went well.

I tore it down and the fan unit and motor seem fine. When I put it back together I noticed that, with some effort, the collet rotated on the shaft. Might be slipping in flight although I saw no evidence of wear in the collet or on the shaft when I had it apart. I'm toying with the idea of putting a little blue locktite in the collet, letting it dry and then reassembling. ;D

[19000rpm]

I got a new collet and the impeller no longer turned by hand but...Yesterday, the impeller came out of the fan I hadn't inspected it for a few flights. Pilot, post-flight, error. KAPOW!

I was concerned that the impeller might have eaten some components on the way out the air intake, but I got lucky there. Fan hub and collet ended up about 10 feet ahead of the jet.

Good thing it happened on launch because this plane glides like a rock with the added weight of the reinforcements and heavier motor and battery.

Hobby Lobby was out of stock on the EDF unit so I ordered a new fan with a 5250kV motor from HobbyPartz. He, he, this is going to be fun and I'll have it this week instead of waiting 2 weeks if I'd ordered from China.