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Old Nov 03, 2012, 09:40 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
7,721 Posts
Adding a fan to the F-5 sport

OK, as promised, I`ve refitted the F-5 style airframe with a fan. No more propjet here.

A few notes, I had to down-size the servos and shift them out into the side skins so that there was clearance for the efflux tube. That was planned.

Getting the weight of the motor out of the tail has allowed me to shift the lipo back into the canopy area where the fuselage is tall enough to house the 370mah cells. So now I have a 3s 370mah, plenty of lipo for a jet this size.

I had to build a new nose, due to a vertical landing that I did last week. Nothing diff, just a new nose.

The Hobbywing 12a 4s esc is in the nose, and the rx mounts between the esc and the lipo.

New AUW is 126g, aprox 4.5oz. Installed thrust is up to 3.25oz, it will get close to 4oz with better lipos
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Old Nov 03, 2012, 10:22 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
7,721 Posts
About the power system

My watt meter was on the blink, so I picked up a new one today. Now the fan starts to make sense.

This is an AEO 30mm with the stock Sky Angel motor. I tried it on a monster 5000mah 3s to see what it would do with no voltage drop. With the cells holding 3.9v (11.7 total) it pulls about 8.5a for a total of 100w. With the wing off that gave over 90g of thrust. With the wing on, now it is starved for air, with the thrust dropping to only 60g. So I cut the cheater hole and the thrust jummped back up to 90g.

The 25c Nanos don`t do to bad. At 8a the system is only pulling 20c from the lipos, and at that level, they hold a full 3.7v early in the run. The total power does drop below 90w, with thrust near 3oz. I`ll eventually try this combo on 4s.
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Old Nov 04, 2012, 12:40 AM
it wasn't me flying that plane
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United States, NC, Wilmington
Joined Mar 2011
701 Posts
Lee, is that the newer 8 blade fan?
i picked several of those new ones with the thick blades that do not bend when you push on the blades..they seem like they can take all the power we can "find" to feed em.....strong blades indeed..
Clipped to 4 that sucker could take some rpms........Chris
Your 5 is looking great so far...
Also,did you flip one of your servos in the back or are you using elevons/tailerons?
Thanks
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Old Nov 04, 2012, 07:28 AM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Yes it must be the new style. I don`t have any to compare it to, but the blades are very stiff. I thought about taking off 4 blades, but for now, I need all of the blades to get the power up. On 2s it was only about 4a (I`ll have to check again) 3s was about 7a and 4s is right at 10a.

The servos are setup as tailerons. If I add servos for the ailerons, I can put one elevator servo on a diff ch, slave it off of the elevator, and reverse it. I`m using the Orange 6ch rx without the case (3.7g).
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Old Nov 04, 2012, 07:39 AM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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4s numbers

I tested on 4s with interesting results. With a big lipo, holding 3.9v per cell (15.6v) it hits 10a+ a little, so about 160w. The 12a 4s esc and motor seemed to handle it fine, but I didn`t measure the temps, only touched them. I`ll measure next time.

I used all of the factory settings on the Hobbywing, but on low timing, I would loose sync at about 1/2 power, so I changed it to medium timing which is 15 degrees. That fixed the sync issue and it ran very smooth all of the way up. It must be hitting 90k to 100k or so depending on the real kv of the motor which Dave says varies from unit to unit. If you figure say 7k kv and 15% losses, X 15.6v it`s right at 90k rpm. Sounds like it too.

I watched Dave`s video on fan balancing and applied it to this fan which was very out of balance. First try, the tape made it worse, so I changed it to the opposite side and bingo, a super smooth fan. Instead of removing the tape and drilling holes, I just removed some of the tape and added thin CA to the edges as recommended. Worked awesome, and only took about 5 min. I did get lucky though. I`ll know if the tape comes off, the diff is amazing. Thanks Dave!

Thrust, measured by holding the airframe nose down on a scale, measures 110g (almost 4oz.) AUW on 4s would be about 4.8oz (130g). I think my Eagletree airspeed indicator is broken, but I`ll dig it out and see if I can check the efflux speed.
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Old Nov 04, 2012, 08:40 AM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Good EDF Maiden and flight #2

The weather is nice this morning so I sucked it up and flew the F-5. It flew well. needs up trim as power is added, and right roll trim to counter the torque of the fan.
I had hoped that with the fan it wouldn`t need ailerons, but it still flies very much like it did as a propjet and needs ailerons. I`m just going to use the two servos that are there for now and add pushrods for the ailerons. Then go from there to decide if I want to have the ailerons and the elevators independent of each other.

It launches easily, even with no headwind and lands very slowly with no tendency to tip stall. So I`m also going to add the extra 12g and fly it on 4s. That should all happen later today.

Over all, it`s a fun little plane, but I want more speed and maneuverability. As usual
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Old Nov 04, 2012, 12:07 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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It Rolls Now!

Here is some detail on the ailerons. The hinges in particular. This is 12lb test mossy oak colored Spider Wire. Easy, clean, free movement, no slop hinges that are almost zero cost.

This sucker rolls now! Had to add some expo and dial them way back.

Need to program some "up" into a mix with throttle so that I don`t have to hold "down" in it to land it.

Next step, 4s.
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Old Nov 04, 2012, 03:07 PM
Team30 Micro EDF
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Adelaide, Australia
Joined Apr 2004
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Lee!!! Where's the video??
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Old Nov 04, 2012, 04:29 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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I knocked the nose off it again, trying to mix pitch trim in with the power. So it will be a few days before video.
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Old Nov 05, 2012, 10:42 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Nose #3 and some paint

Well I got the third nose built tonight. Even though it`s getting a little beat up, I went ahead and put some paint on it. Not the prettiest jet in town, but it will look good in the air.

While the wing was off, I also opened up the cheater hole a little more and got a better path into the fan.

I`ll test it on 3s and 4s tomorrow and see if it helped any.

I broke my glasses last weekend (they needed to be replaced anyway) so I`m stuck with a 10 year old prescription until my new glasses get here. They are supposed to be here by Sat, so I think I`ll wait on them before I fly it again.

I flew it Saturday with the old glasses. As long as everything goes smoothly I can manage, but if I get in a bad situation it`s harder to recover. That was part of the reason for nose #3.

In the mean time, I`ll work on the curvy airframe.
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Old Nov 11, 2012, 07:13 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
7,721 Posts
New Sport Jet " Nano Hot Spot"

Well the F-5 airframe just got too porky and hard to trim. I had several good flights on it, but it weighed 4oz after many repairs and two paint jobs. It needed 3s 370 to fly and wasn`t as fast as I wanted, so it was time for something diff.

I built a wing like this as a 1s prop jet . It was great for very calm conditions or indoor. I need to do another one of those. It only weighed 27g rtf.

First I built the motor pod and got the fan running smooth on 2s, total on the pod was 18g and it had good thrust on 2s. It looked like adding it to the prop jet airframe would only put the auw at about 63g with a 180mah 2s and 70g with a 370mah 2s. Now it`s at 90g on 3s 370, but that`s for tomorrow.

This thing flew right off the board at 70g, for flight #2 I shifted the cg back a little and added some up elevator travel to help flare on landing. I flew it 5 or 6 times today if fairly gusty conditions and once late (almost dark) in light wind. This thing is a blast to fly and gets 3+ minutes of hard flying, 4+ with some throttle management.

I`ve decided to try it on 3s, so I`ve fitted my Hobbywing 12a esc and have shifted things around to get the cg right on 3s. Should be interesting.

Here are some pics.
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Old Nov 11, 2012, 07:58 PM
Team30 Micro EDF
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Adelaide, Australia
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Looks fast just sitting there Lee!
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Old Nov 11, 2012, 08:17 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Thanks Dave. I`m going to order a couple of your 30mm pods. With that and a couple of minor changes, this will be a really slick little jet.

I just measured 125g of thrust on 3s at just under 10a, just over 100 watts. This is about 25c drain on the lipos at full power. The AUW is 90g! 140% Th/Wt ratio!! I`ll fly it tomorrow, if it doesn`t fly me first. LOL
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Old Nov 11, 2012, 08:51 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Ready for some 3s action

It took a little doing, but I got everything tucked in place for a 3s flight in the morning if the weather is decent.
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Old Nov 12, 2012, 07:47 AM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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3s Flight

Flew it this morning on 3s. Had a bad servo and crashed after some good passes. I'll put it back together and try again.
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