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Apr 25, 2011, 05:27 AM
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MIA S300 - Nine Eagles Bravo SX / Solo Pro mod

MIA S300 - Nine Eagles Bravo SX / Solo Pro mod

This MIA S300 heli with Nine Eagles Bravo SX parts flies fantastic. It easier to handle, more stable, much better in turns, and faster than the (very well flying) NE Bravo SX (and by far better than all my Solo Pros). Additionally the S300 is much more silent than the (very lound) Bravo SX, even the Solo Pro is much louder.
I have several fixed pitch helis (several Solo Pros with different mods, several Bravo SX, CB100, 4#3B), the S300 is my favorite one. It is the best flyer of all, the by far best „lander“, and it looks quite nice.
I have built this heli in December 2010. The MIA kit is easy to assemble, to fit the Bravo SX main frame needs a bit of surgery – the tail boom bracket of a second main frame has to be cut out and glued into the frame for the MIA heli, if the MIA tail boom is used.
I have reported these mods already in December in this and a German forum. But since the pictures of those posts are not available any more (server died) and I have been asked several times fort he MIA S300 Bravo SX, now again a report.

This report is dedicated to frieslander, who "forced" me to write my own blog!


From MIA microflight (

• „MIA S300 Scale Frame Kit - mSR, mCX, Solo“ (US$ 19.99)
• „MIA S300 Scale Canopy Kit“ (US$ 9.99)
Shipment is cheaper, if you ask Sylvia from MIA – I paid only US$ 8.50 to Austria (Europe).

• A Nine Eagles Bravo SX (will probably also work with a Solo Pro)
• A second NE main frame (Bravo SX or Solo Pro) – you will have to cut both frames
• CA, Epoxy, sandpaper, tools

I decided to take a Bravo SX for the mod, because the frame fitted better to the MIA skids and the Bravo SX motors are stronger than those of the Solo Pro. Solo Pro should also work.

NE Bravo SX and Solo Pro main motor and P 47 motor have exactly the same size. SP main motor is weaker and has thinner wire leads.

Assembling the MIA frame is easy, use CA and/or Epoxy. Be careful when cutting out and sanding the single parts.
I took the tail boom bracket of another Nine Eagles frame, cut and sanded the frame for the MIA heli on adequate sites, and glued the new bracket to the frame with CA. Afterwards I tightened the joints with 5 min epoxy. Afterwards I recoginzed, that mounting the new bracket about 1 mm lower would have been better (for fitting the tail boom tot he MIA alu tube). It works, as I did – if anyone also wants to this mod: bracket 1 mm lower.

I have used carbon rods as canopy and tail-skid mounts. Glued to the main frame with CA + epoxy, ends sealed with a drop of CA.
Some weeks later I recognized, that the rod for canopy mounting is slightly skew, and the right lower part of the canopy sometimes touched the main gear.
I glued a further short rod to the frame to keep the canopy away from the frame (the rod without rubber ring – there is no opening in the canopy for this rod, it is plugged only to the rod with the rubber ring).

The alu boom of the MIA kit is a little too short for the Bravo SX tail boom. I tried a longer alu tube, but this resulted in worse flight behaviour. Probably shortening of the Bravo SX tail boom would work, but this heli flies so well now, I do not want to change anything.

I used a Solo Pro rx for the S300, not the rx of the Bravo SX. It is the same rx, the Bravo SX has only additionaly a light.

MIA suggests to use „Eflite-micro type“ batteries, which fit into a bracket of the skids – but this kind of mounting is quite ugly (battery outside below the canopy):

I use bigger and stronger batteries now, Zippy 240 mAh, Hyperion 240 mAh and Wellpower 250 mAh. Zippy is the smallest one, Hyperion is a little larger, Wellpower again a little larger. All batteries are quite good, flighttimes 6 ˝ (Zippy) – 8 – 8 ˝ min (Hyperion, Wellpower), power ok in all batteries.

Turnigy Nanotech 160 mAh, Zippy Flightmax 240 mAh, Hyperion 240 mAh, Wellpower 250 mAh

Zippy (easy) and Hyperion (little harder) fit between the brackets of the skids – no additional fixing is necessary. Cable is below the canopy, so this kind of mounting looks quite good.

But it is easier to change and fix batteries simply with a rubber ring for mounting, and this way you can use many different types of batteries. Disadvantage: cable outside, not hidden. Changing batteries is very easy this way.

I tried also the new (huge) Zippy 240 mAh 30C – this battery is not better than the other ones in the MIA S300 (and way too big for it). This strange battery (about the same size as the 400 mAh one, only thinner, 240s: ~ 63 mm x 24 mm, 400 are 4.1 mm in diameter, 240s - 2.85 mm, weight of the 240 is 9,68 g, 400 13.14 g, including long wire and JST plug. After discharging to 3.0 V I could charge 345 mAh to the 400 Zippy and 206 mAh to the 240). Of course I have changed the mini JST plug to a micro one to fly it in the S 300:

The soldering joints on the rx are quite weak. When changing batteries, there’s always little force (pulling) to the joints, so they can break and the connections can get loose. I made this mod, a small plastic joint bar (from a Walkera 4g3 foam blade), screwed to the rx, takes all pulling force from the soldering joints – they cant break anymore:

The MIA S300 has about the same weight as the Bravo SX, about 29 g:

This is a perfect little heli. It is extremely durable – did not have any problems yet. No flybar strikes, as we know from the Solo Pro, no broken skids (in a crash the alu skids are maybe bent – can be bent back easily without any damage), and if something of the MIA parts breaks, then in the joints – can easily be glued again.
Because this heli flies so well, I did not use any upgrades (Xtreme swashplate, …) – simply not necessary.

This MIA S300 is highly recommended to anyone who likes tinkering and wants a special, „better“ Nine Eagles heli.

My "first version" - afterwards I have changed the blades to black ones and used black shrink tube on the tips of the alu-skids:

On this short video you can hear, how "silent" the MIA S 300 Bravo SX is:

Nine Eagles Bravo SX - MIA Microflight S300 (0 min 31 sec)

And here the sounds of Solo Pro and Bravo SX:

Nine Eagles Bravo SX vs. Solo Pro - loudness (0 min 30 sec)
Last edited by Donaldsneffe; Apr 26, 2011 at 06:39 AM.
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May 24, 2011, 01:49 PM
Registered User
McCauley's Avatar
Good job, pretty copter! Nice videos; great explanations. Very cool.
May 25, 2011, 06:12 AM
Registered User
StefanS's Avatar
nicely done - looks very solid. The detailed description and all these pictures combined, make a nice how-to on modding Nine Eagles helis. thx!

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