Saving another MiniProtos

[sp00fman]

Beginning this year i got a used mini that i fixed, It was in pretty bad shape the way it was build up. No eye for detail and links and levers binding all round. The thing was crashed twice. but with a few spares (most came with it) and bearings it is just as new. I really like this heli and comparing the belted Trex450 clone is a maintenance nightmare. Prone to belt slipping and wear of front and rear pulley.

Thursday stumbled on another used miniP and could not resist, I am now half way in the rebuild. It is an older kit with old swash and an motorshaft adapter, looks like is has seen at least one other previous owner and lots of ground contract.

The guy i got it from stated the miniProtos showed him that flybarred helis are not worth it.... and he stated this heli might need longer tail blades because it wont hold well.

I can imagine that now! .... the complete head was binding up so badly the servos would have struggled even to lift off, He used a flybarless feathering shaft on his flybar-setup and got the wrong washers between the thrustbearing and outer radial bearing, so it would compress the bearing instead of relieving the stress. The bearing in the A-motor shaft support was all but gone, the tailgrip bearings were so notchy they could just as well have fallen apart.
I cleaned everything up and the only bearings i did not replace was on the pitchslider, one mainshaft and the roller bearings. The rest was shot!

Is there truly no love for these beautiful helis in the Netherlands? Maniac heli butchers!

All is not bad with my purchase, came with original canopy in decent shape. The frame only has a scratch and with the few spares that came with it, there was a low FBL hub! I kind of wanted that already!
New Align DS525m tailservo and the original motor (yet to inspect and put in long shaft)
Had all the bearings on hand, so no big loss.

Put in new dampners and FS to be safe and the head and tail parts are all done now. The tail is butter smooth and the head is not notchy at all.

All that is left is clean the frame sides and rip the electronics from the 450. One roller has a bit broken off, and i might need to replace that before the test flight.


Anyone have a spare plastic roller for me?

[Chris Nifty]

Wow, what a story. Good karma to you for the Mini rescue. I'm waiting to hear about the successful maiden

[Mikej]

Spoofy,

I saw your other post saying that you had almost finished your build and was completely confused since you had your M-P earlier in the year

Great to hear that you are building a Mini Protos sanctuary / hospital, i'm tempted to follow suit . I did manage to get a second Protos 500 for a very good price that someone had crashed and couldn't be bothered to fix, just need another Mini protos now ...

Cheers,
Mike

[sp00fman]

Hey Mike! Join the club!


The fact all the important bits are still usable after all the abuse it took really is a testimony of the quality.

By the way, i though the hollow mainshafts were black. this one came with two metal colored ones. Dimensions are the same.

This heli will be equipped with led strips for night-flying. I need something that lasts and holds its tail.

I have also been eyeballing the Protos500. Not as many good deals to be had, and most fly-barred and overpriced. Not looking forward to fork out extra just to upgrade the head. Also i think the P500 is just a bit on the small side, not being different enough from the mini.

But perhaps one day i might just try one, if the conditions are right.

[jmisuraca]

Nice save.

I have one but think shipping to you would cost more then buying new.

[dr dremel]

Can relate to this as this bird just keeps going with little maintanance and I need something to wrench on over the winter.

I´m biting my *** over a missed ebay opportunity a few weeks ago, naked used airframe sold for 80€, would have been nice to resurrect another.

[Mikej]

Originally Posted by sp00fman

I have also been eyeballing the Protos500. Not as many good deals to be had, and most fly-barred and overpriced. Not looking forward to fork out extra just to upgrade the head. Also i think the P500 is just a bit on the small side, not being different enough from the mini.

But perhaps one day i might just try one, if the conditions are right.

The P500 that I got was advertised pre-crashed for "offers" - so I made an offer that I thought he would reject and I would get it for a few pounds more - and he accepted it .

FBL, with Hyperion motor and 3 DS510 servos (one with stripped gear), but no undercarraige or tail blades - everything else (except FBL unit, tail servo and ESC) included - even had a nice canopy and blades.

I bought some new gears, fitted a FUBar and tail servo that I had waiting for a heli, and bought a new YEP esc, undercarraige and tails and it was in the air for about €120 (not including the bits that I had already bought)

I know that a lot of people won't buy second-hand, but for me it's an no-brainer

[sp00fman]

I was wondering why the seller was so quick to react, and it was in my hands within 36 hours. Considering the state it came in i might have gotten it cheaper, but the Low hub + €25 Align tailservo, the kit with motor cost me €100. hellofa deal imho. The Chinese bearings i put in would be under $10 and they tend to hold up fine for me.

Put in a few hours of cleaning and assembling all the bolts. Its the part that gets tedious, but it is a helicopter again, ready to accept the servos and electronics.

I still need that roller. annoying there are no resellers with mini parts left in the netherlands.

[Mikej]

Originally Posted by sp00fman

Considering the state it came in i might have gotten it cheaper, but the Low hub + €25 Align tailservo, the kit with motor cost me €100. hellofa deal imho.

Sounds like a bargain

Originally Posted by sp00fman

I still need that roller. annoying there are no resellers with mini parts left in the netherlands.

Let me know if you still need one, I'm fairly certain that I have a spare that I can send you ...

[sp00fman]

Found a set for €12 shipped. Have to wait a few days before ordering. Perhaps look a bit further for the metal ones. Servos and drivetrain assembled. I can start checking if everything spins true and then install the rest of the electronics.

[sp00fman]

First spoolup showed a vibration on the tail, so installed a new tailshaft, Much better now but the pitch slider is not smooth at target RPM. if i push it, it resists and then jumps over a little. Does not get back to center on its own. Looks like one of the radial bearings is not playing along with all the axial load. Instead of messing around with more bearings i took my Tarot thrusted tailrotor and got it installed on the MSH hub with a few simple modifications.

Oh boy does it move smooth when spooled up!

The whole heli runs smooth with just a hint of vibration from the tail. I should get it even better with a piece of balancing tape on the tailblade.

Everything set to take the FBL controller and Rx. This 2218 2500kv motor is known good, but the scorpion has less bogging and runs cooler. Will make the switch later on.
Running 335mm mains (root to tip) i measured everything up and can conclude i have a theoretical minimum of 5mm space between the main and tailrotor, should the rotordisk deviate in a hard cyclic move.

Note that i extended the swashplate antirotation pin with an extra bearing. There is no way it could jump off in flight. The hole in the bottom plate was the prev owners modification, to be able to stock a hex key through for the mainshaft bolt. I like it! made the build even more enjoyable.

[jmisuraca]

Originally Posted by sp00fman

The whole heli runs smooth with just a hint of vibration from the tail. I should get it even better with a piece of balancing tape on the tailblade.

Awesome job. Yep. A little balancing tape does the trick every time.

[maarset]

How did you modify the tarot thrusted tail grips to fit on the mini protos spindle?

[sp00fman]

The tarot grip bearing slips over the 4mm part of the hub spindle. the other bearing and thrustbearing match the 3mm part of the hub.
I had to put ~1,4mm of washers between the bushing and the tailgrip lever to get geometry back. The rest is almost a perfect fit. The MSH tailhub spindle is 1mm short, so the outer radial bearing is only partially supported on the ID. I rust ran it like it is now. don't expect any problems in flight. Just dont overtighten the screw, or you will crush the inner radial bearing onto the hub root.

If you can find a fitting busing to put in the outer radial bearing it would be better. Should be something like 2x1,5x3 mm.

The whole mod only makes the tail rotordisk 2 mm bigger in diameter.

[maarset]

Very Cool. Thanks for the info.
I might give it a try

[sp00fman]

Just ordered the metal pulleys and a long motor shaft to upgrade the stock motor with.
Will arrive in a few days so time to get off my ass and install the FBL controller. I will use the Tarot ZYX-s again, so i have two electrical identical heli's,
One stock, and the other with low head, metal pulleys, CNC third bearing support and thrusted tailgrips.
I will be able to directly compare the two and test some more things. I dont really expect a lot of difference, but who knows

[sp00fman]

yesterday evening i installed the FBL controller and copied the FBL settings to the new heli. Only needed to set the trims, the rest was dead on. I noticed the servos buzzing because of binding on the head at the cyclic extremes. I see the old style swash does not allow for the same amount of cyclic throw, because the bottom of the swash will hit the mainshaft. I deiced to trim off some material from the inside of the swashplate. It was pretty easy to do with just a sharp exacto knife chipping the material away and respecting the angle of the shaft at cyclic extremes. Lucily it worked and the swash did not fall apart in 2 pieces. I dont have any binding left.

CNC roller bearings are in. Tomorrow I might be able to prefect my swash linkage lengths, do a complete assembly check and maiden the heli.

[Mikej]

Spoofy,

Are your electronics similar on each heli?? - I'm keen to see what difference the lower head makes to flight characteristics. I would love to change to the lower hub, but don't want to change how it flies.

Cheers,
Mike.

[sp00fman]

Exactly the same except tail servo. It is all set up for the maiden flight, but am waiting for the right moment. After the first tuning flights i will take both heli's to the bigger field to get a direct comparison.

I will report back here.

After that it is upgrade time form one (bling-bling) and the other heli gets all the nice led lights strapped around.

[pgleesonuk]

Originally Posted by sp00fman

The tarot grip bearing slips over the 4mm part of the hub spindle. the other bearing and thrustbearing match the 3mm part of the hub.
I had to put ~1,4mm of washers between the bushing and the tailgrip lever to get geometry back. The rest is almost a perfect fit. The MSH tailhub spindle is 1mm short, so the outer radial bearing is only partially supported on the ID. I rust ran it like it is now. don't expect any problems in flight. Just dont overtighten the screw, or you will crush the inner radial bearing onto the hub root.

If you can find a fitting busing to put in the outer radial bearing it would be better. Should be something like 2x1,5x3 mm.

The whole mod only makes the tail rotordisk 2 mm bigger in diameter.

I'm having a into this look at this too. (Tarot thrusted tail grips)

Seems to be you can get the bushings you need by taking an MR31 bearing (1x3x1.5) and punching the balls out. It's the accurate OD and width you want.

Also, using M2x8 bolts, they bottom out on the threads in the hub, giving just enough gap, so you can tighten the bolts properly and not put pressure on the inner radial bearing.

As an alternative, I'm also trying turning down the Mini Protos standard tail shaft to 3mm, if I can find a friend with a good lathe.

Let's see