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Old 02-28-2014, 03:07 PM   #1 (permalink)
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Default My Stealthy Stretched Mini Protos (Build Report)

My Stealthy Stretched Mini Protos
With the help many of the great Protos forum guys, this heli has been a fun build. I ran into some gnarly problems early on getting the bearing blocks to line up but once I got past that hurdle everything went smoothly.

I was a bit taken aback initially that there was no paper manual since I like to write notes on my manuals, but that was a non-issue after I printed one out. I have to admit that occasionally it was pretty nice to look at the electronic version and blow in up on screen to look at specific details. It was also cool that an updated manual came out mid build.

I didn’t take the choice of the Mini Protos lightly. I was in the market for a high quality 450 size heli that I could put my first bail out system on in hopes of it becoming my "go to" trainer. The consensus after this thread was the MiniProtos or the JR Forza:

The MiniP was a proven design and readily available so it was my choice.

The next question was whether to stretch or not. I’ve always found smaller helis to be somewhat squirrelly so stretching to larger blades seemed worthwhile.

The next question was 3S or 6S. This one was a bit harder. I opted for 3S since it was the stock configuration and so that I can swap batteries with my planks and my TREX 450SE. I may still shift over to 6S if I’m not happy. Time will tell.

I opted for the short head tee since I didn’t like the looks of the hole where the flybar could have gone on the stock head tee and I liked lowering the disk. I also opted for aluminum pulleys just because I liked the looks of them as well.

Finally which pinion to use. It comes stock with a 16 tooth version but I opted for a 15 tooth for longer flight times. Only problem is that I ordered a 15 tooth for the 500 size Protos, like a dummy, so I am using the 16 tooth, for now.

The Mechanical Build:
Do NOT follow the manual and put together the servos and bearing blocks first. Put together the frames and bearing blocks aligning them with the main shaft as you go. Once you have the frames and bearing blocks aligned and tightened, proceed to tighten screws on the rest of the frame and add the servos. (make sure you have the bearing blocks properly spaced for your servos though)

If you want to mount the DS95s using 4 screws rather than 2, you will need to do some work. I widened each mounting hole with a rat tail file on the DS95s to allow the screws to fit properly. I had some stainless screws laying around that I sell with certain products so I used them to mount the servos and all my aluminum parts. I'm not usually into bling but they do look pretty nice IMHO. Also, I had to lengthen the middle bearing mount slots in the frames to allow the middle bearing mounts to shift low enough for the DS95s to fit in properly. Its much easier to just mount them with 2 screws and I'm sure they work just as well. I'm just a glutton for punishment I guess.

Note: The frame sides are not identical. Make sure the holes next to the boom blocks are on the correct side.

This thread outlines everything you need to know to get your bearing blocks aligned.
I highly recommend the aluminum bearing blocks.

For the FBL head, use the long spindle and wide spindle spacers. Its normal for the grip to be a little notchy with no load. Thread here:

When you put together the plastic halves of the tail assembly, you may find that it will not close flush. I tried different bushings on the shaft to make everything the right width but ultimately I didn’t have anything laying around that would make it perfect. I had been told not to tighten the two halves together snugly and I assume if it had it would have deformed them. As an alternate approach, I put in a spacer between the halves on the rear screw. It seemed to solve the problem and I’ll look for vibes later.

When you build the tail slider, make sure everything slides smoothly. If there is any binding whatsoever, takes steps to resolve it. On, mine, the arms that push/pull the slider were binding just a little. I reamed out the two holes in the arms with a 1/16” drill bit in a hand chuck. Do each hole from the outside rather than trying to align the bit and go the whole way through both. Don’t ream out the inside holes on the edges of the slider since they hold the pin in place.

There is not much to note for the rest of the build other than the link lengths for the cyclic servos were changed from 17mm to 18.5mm in the new manual. Mine links ended up spot on and my swash perfectly level with NO adjustments. That was a first!

Other than the bearing blocks, the mechanical build was sweet. I like the innovative belt design and how quiet it makes the drive train along with how simple it makes the overall design. I’m still a bit worried about the pinion/OWB. Time will tell how that holds up in my particular build

I really like that there are three bearings on the main shaft and that the motor has a counter bearing as well as the sliding motor mounts. These are all things I like to see but seldom see on small helis.

The socket head screws are high quality and much better than the button heads used in some designs.

I also like the other little niceties like the screws ends for the CF tail rod linkage and the holes pre drilled at the right locations in the frame for wiring. I only had to drill one extra hole during the wiring job.

Overall, other than the plastic bearing blocks, I thought the mechanical build was very well done.

One nit: I love the look of the stock canopy but I’m not that thrilled with how difficult it is take it on and off. I may well replace the stock mounts with some quick connects but I hate to add any more weigh to a heli that’s already a tad tail heavy.

Update from dr dremel: For easier canopy removal/attachment you can smear a little silicone/oil on the posts. I also glued the rubber grommets in the canopy so they do not deform during install. Further more I would recommend to coat the ears of the canopy (from the inside) with a thin layer of epoxy or similar to prevent cracking.

Update in response (Thanks Doc):

The Electrical Build:
Since my earliest builds, I have always followed the following set of rules. That proved to be very easy with this build.

1) Isolate high current noisy components (Main Battery, ESC, and motor) from low current parts (Antenna, Battery, gyro, gyro controller, and receiver)
2) Protect all components from crash damage
3) Make heli parts you replace regularly easy to replace (Bottom Plate, Tail boom, belt, tail pulleys, etc)
4) Keep wiring runs short
5) Protect all wiring

I’m always a bit leery about static buildup with belt designs, but I was convinced by the helifreak community that static is not a problem with this heli. My guess is that the belt from motor to tail keeps the entire heli at the same potential so no hot spots of electrical potential are able to build up at inopportune locations. Thread confirming no need for anti-static strapping here:

I opted to use the stock ESC since it seemed up to the task and the community likes it. It also fits well in the intended location under the battery mount. The one drawback to this mounting is there is no easy way to disconnect one motor wire for safe maintenance. I was tempted to run the motor wires along the outside so I can get to them, but I like the clean look of hiding them for this small heli.

Update thanks to dr dremel: Instead of disconnecting the motor leads I just remove the belt from the pinion. If you slide the belt down from the maingear there should be enough slack. One of the nice details IMHO, no pinion mesh to mess up

The main point of this build was as a trainer so I knew I was getting the Baverian Demon well before I even knew which heli I was going to build. I basically built a heli around the BD. It turns out the wiring to the BD is very simplistic like the VBARs I am used to so it allowed for a very basic wiring task. I did use a custom lexan mount as a more solid mounting surface that was big enough to accommodate the BD.

I took Capi’s lead and used heat shrink to protect my wiring for this build instead of braid. Both do a nice job and I do like how the shrink keeps the wires in place with no stress on the BD.

I like that it will be really easy to connect the PC line to the BD when I am doing adjustments.

I used one satellite for now but I may add a second underneath if I have any connectivity problems. I used the 3 position Aux3 switch on my JR X9503 transmitter to control the bail out feature but I’m up for suggestion of a better place for that. I still have some homework to do on that one.

Edit: Found a great thread on this:

Left Side

Right Side

With Canopy

Thanks to MSH for a design well done and all my helifreak friends that helped to make this build go so well. Building this was a blast and many thanks to Bill at for feeding my addiction!

I hope this build was informational and fun and hopefully it will make other peoples builds go more smoothly.


Some of my other builds:

Ravenous Rush 750 Build

Sexy TREXY 500 Build:

Lovely Logo 400 Build:

Wiring Sheathing Tutorial:

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Last edited by rdlohr; 03-02-2014 at 11:19 AM..
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