Protos tru-500 super stretch

[Jomaba4308]

I know it's been done already but I can't find the info again. I have found a 3M-1530-6 belt which would add 33mm to the length of the tail. The standard stretch belt is 3M-1464-5 and will clear 480mm main blades with about 6mm to spare (give or take), if my math is right this 1530mm belt should clear 510mm blades with about 9mm clearance (give or take).

How did it fly?
What is the length and diameter of the MSH stretch boom?
Could the airframe/head /motor withstand the added stress of the longer blades?
Possibly need lower kv motor? If so what motor?

Blade choices that I've found so far:
SAB 500
Cyclone 505
Halo 510 (I like the 360's on my Mini P)
Zeal 500 (very sceptical of Zeal)

[Stoparach]

What a funny idea... I don't think protos flies better with 500 mm blades. It's already a super light heli with a low disc loading. You should try a true 550 before that.

[Jomaba4308]

550 is too big for me right now. I watched friends fly Trex 550's and that size still scares me but the Goblin 500 doesn't. I've thought about getting one but can't afford Goblins.
I found Cyclone 505 blades which are more appealing to me than Halo.

[TitaniumFreak]

well this might be the older thread .https://www.helifreak.com/showthread.php?t=597884

I currently have rail 516 in it now . I still have the pictures in my albums

[Jomaba4308]

That's the thread I saw. How does it fly with 516 Rails?

[TitaniumFreak]

it is pretty light on the pitch and cyclic. now the plastic blade grips are a problem . ive had failures with the long stand ball links on the grips breaking . and with the limited number of motors with the lower kv is a problem with the protos 500 gearing to go lower headspeed . but man is it stealthy at the lower headspeeds. I really haven't flown it much still . I kinda of lost interest in it. I have thought of running a 4 cell battery with the tareq motor and keeping the 15 or higher pinion for the rpm I choose. but I really haven't given it much time lately.

[Jomaba4308]

Actually I've read that some fly the Goblin 500 with 500 blades as high as 2800 rpm so I don't see why 2500 would be a problem for the Protos. I just set mine up with the 13t pinion and 1900 up to 2300 rpm.
Is it the plastic grips at the long stand balls or the link balls themselves that are breaking? Luca told me he is working on DFC head for the P500 which knowing Lynx will be metal but he didn't give an eta. Maybe there are metal grips from something else that will fit the Protos wether they fit the Protos spindle as is or you import the spindle & dampers to the Protos head.

[deebee]

I know rjx makes a metal protos 500 head goes for around 65 or 70 dollars and has multiple j-bolt holes allowing adjustable head height.

I have been experimenting with the X4 head it will fit but the Protos main shaft has to be re-drilled, swash balls for the washout arms need to be changed to X4 size as do the ball link ends where the connect to the grip arms, or the x4 grip arms need Protos balls your choice.
The X4 head is 15 or so mm longer adding to the total rotor span.

The one thing I am not yet sure of yet is if the protos swash will have enough throw to get good blade motion with the longer X4 grip arms.
I need to take some measurements and do the calculations to figure out how much cyclic and collective will be available. If the swash has to be changed to the X4 swash, cost and difficulty would make this a poor choice beside the rjx head. Unless the additional length bolt to bolt on the grips would provide a better fit for a standard sized blade with a certain size belt.


I just pulled the trigger on a 1530mm x 6mm 3mm pitch belt and a 15mm id X 17mm od x 500 mm piece of carbon tube which I plan to cut to fit the 1530mm 510 tooth belt. Should allow clearance for true 500 blades. I got a feeling that I will need that heavy 4000mah 6s battery I just let go of.
Curious if I got the right belt
http://www.ebay.com/itm/321195839283...%3AMEBIDX%3AIT
And the boom 17 x 15 x 500
http://www.ebay.com/itm/131408420468...%3AMEBIDX%3AIT


I also have a 4260 600kv motor w/ 5mm shaft laying around. If i can get this to work i should be able to use a larger pinion hopefully eliminating excessive wear. 20t pinion or possibly a 7s lipo and a 16t or 17th pinion.
It's 42mm od by 60mm long. hopefully will fit just right by the time I space the motor down enough to clear the frame. Thinking I might stack another motor mount under the current one, with maybe a washer or two in between if I must.

Has anyone done this or seen it done on a Protos? I have heard of people using 3226 motors 41mm can ( it has a taper at the top), and I think someone had used one a little bigger than that......I however cannot recall how they spaced the motor down to clear the frames and if the shaft was cut down or not.???

I know this is alot of info, speculation and possible options and this is exactly why I am asking for input from those who have been there, or have already cleared some of these hurdles.

[TitaniumFreak]

this was a cobra 3525-780kv motor he trimmed the frames

[deebee]

That was a pretty slick mounting job, unfortunately the motor I have would require shaving the frame all the way along the mount and certainly weaken the mounting slots.


I doubt I will end up putting a 600 kv motor in my Protos.
7s really isn't a viable unless I custom make a 7s 2600mah pack, or run 2x 4s 2200mah packs.

I do have a 3226 that has already been torn down. I could always rewind it, would need nomex, fg wire sheaths, wire and a new set of skills....lol
I was looking at a chart with various winds x turns and the resultant KV looks like I could get high 700 ' s maybe 800 ish kv.

Anyway sorry to hijack....
I recently put on a semi-generic set of 470mm blades, dropped to 13t pinion and am loving it. Makes me anxious to give a 500 mm plus stretch a shot.
I was actually able to find a belt and boom, both on flea-bay, that i think will work ok.
Not sure about the belt at 6mm wide, it is a 3mm pitch HTD (1530-3m-06) <----Not sure how this matches up to GT-3mm or S3M?

[DoubleCH]

Originally Posted by deebee

That was a pretty slick mounting job, unfortunately the motor I have would require shaving the frame all the way along the mount and certainly weaken the mounting slots.

Instead of shaving the frame, shim the motor from the motor mount to clear the frame.

[deebee]

I had considered placing an additional motor mount between the stock mount and the motor. Should be sturdy and will clear the frame.
What I don't know is if it will drop the shaft to where it needs to be to high I can trim it to low and maybe I can use something else to shim it the correct distance?

[DoubleCH]

It's very likely the shaft is too long because stock shaft is short and specifically cut for protos to run shaft adapter.

Don't worry too much about cutting or shimming to the exact height. There's a little bit of leeway to mount the shaft adapter onto the shaft.

[deebee]

That will definelty help, I got a set of 500 blades in today they are a full 10 mm wider (48mm) and nearly 40 mm longer than the 470mm blades I am currently running 2350, 2400, 2450 with. This is down from 2400, 2500, 2600 the latter which was pulling more power than I wanted. Looks like I will be able to run down around 2200 or less with 500 blades.


Anyhow cf for tail boom, extended boom struts, and pitch rod is on the way as well as some 76 or 78mm or so tailblades they are supposed to be 6mm longer than other 500 sized blades. I probably will end up using 80 something tail blades before its done. Also found a 1569-3m -05mm belt (source in the other P500 stretch thread is back up), also found out that a 6mm wide belt would almost certainly need to be trimmed down.

I have still yet to get the additional motor mount and 17t or 18t pinion for the 600kv motor.
I am looking fwd to doing something a little different, even if not totally unique.

Headspeed /((600kvX22.2vX.85eff) / 93) = MPt
2200rpm = ~18t
17t = 2069rpm

Mr. Mel's says (with 35c and 85% Peak eff.)
17t 1974, 2053, 2112
18t 2090, 2174, 2236
19t 2206, 2294, 2360
20t 2323, 2416, 2486

Going to 45c adds ~50 rpm across the board
Going to 90% Peff adds ~125 rpm
Think i will start with 18t.


Ordered these as well.
SAB Blackline 2Dhttp://www.helidirect.com/sab-500mm-...orange-2d.html
500mm long, 43mm chord, 10mm grips,4mm bolt hole.
Should do nicely. I hope

[deebee]

link for 1569-3m-05mm belt is. You have to buy at least two
http://shop.polybelt.com/1569-3M-05-...9-3M-05BNG.htm

And for a 17 x 15 x 600mm boom is.
http://www.ebay.com/itm/221607275420...%3AMEBIDX%3AIT

These have been tested and verified to work by other HF members who have also stretched their Protos helis.
600mm boom allows for up to 90 mm longer blades 475 -> 565 or basically it will clear 550 ' s or better.
The 1569 belt is said to need a 550-560mm boom length. 50mm more boom length gives us about 520mm or so for usable blades as well as a little room for 80mm tail blades maybe more.
Looks like it would take around 1650mm or more belt length to hit 550 blades and have room for 58mm tails seems 1800m is the next size available.

I don't know how the disk loading will feel with 500 - 520mm blades, but I do know efficiency will go up, and headspeed will go down for longer blades with similar chord and thickness.
In the 500mm range seems 42-51mm is the thinnest chord, which is similar to some of the wider chord 430mm blades which the Protos seems to have plenty of power for.

Makes the argument for a more powerful motor seem pointless, the main advantage is to be able to go to a lower KV motor 600-700, while keeping pinion size at 15mm or above. this will allow you to avoid switching down to a 4mm shaft and 12t pinion, which probably wouldn't last as long.

[deebee]

Finally I have all the bits together in one place.

Belt, Boom, pitch rod +ends, longer support rods( may not be needed).

I currently have SAB 500mm Blackline 2D, HTB 500mm and 510mm blades (12mm root, wide, heavy), and a set of Zeal 500mm, 43mm chord on the way.

As well as an 80 amp esc, 4260 600kv motor, 18t and 20t pinions

BELT 1569mm X 3M HTD X 05mm
Boom 17mm X 15mm X 600mm
P rod ends 3Rd party Rex 550 on clearance helidirect
Tail Pitch Rod 5mm X 3mm X 750mm ?cut in half for boom supports?
Boom supports 4mm X 3mm X 750mm 2 pieces ? Pitch rod?


Main Blades SAB 500mm X 43mm X 10mm X 4mm 90g
Zeal 500mm X 43mm X 10mm X 4mm 95g
Tail Blades Lynx 72mm, Mav 80mm cf (wide), China 80mm plastic

ESC Hifei 80-KK-6s 80 amp Data logging esc
Motor China 4260-06 600kv 1500watt 42mm x 60mm x 5mm shaft

MSH 18t and 20t motor pinion
MSH 18t tail pulley
MSH +1 Motor mount to space motor for fit.

[TitaniumFreak]

Looks like your ready

[Jomaba4308]

I'm anxious to see it and hear how it flys. [emoji15]
For that matter post a flight video if you can.

[deebee]

I am super excited. But then again I was super excited to get a couple flights in today with the stock stretch 470mm form.

But as far as I know I got all the pieces. I plan to fly right up until everything is ready to bolt up, then do the swap in stages.

I will try to get a decent video, although I'm pretty sure my thumbs are not up to the task of showing what a Protos 500mm is capable of.

Lol, No shame here tho', I have been on cp for a little over 2 years, hardly get to fly, and rarely hit the sim. It is a wonder I don't forget how to hover.


NItty Gritty Numbers and such
To TitaniumFreak, Jojamba, and anyone else that's already been there. Please correct me where I'm wrong, let me know if I miss something and don't hesitate to add or suggest a better way)


First order is to measure cut and fit the Boom, belt and pitch rod.

1569mm new belt - 1464mm factory stretch belt =105mm difference
I need a boom 52.5mm longer than a 510mm factory stretch
I know 18 and 20 pinions will take a bit more belt.
you gain 3mm belt length per tooth or 1.5mm boom length
I plan to go with 510 + 50mm or 560mm boom length.

Initially i want to hold back 2mm on the slot until I get a test fit and verify the belt will still tighten on the 13t pinion on the 880kv motor.
Then once I go to the 600kv motor and 18 or 20t pinion I will add the extra 2mm to the slot if needed.

Also will have to add another 52mm to the tail pitch rod as I want to keep the servo as close to the frame as possible.
Then the placement of the horizontal fin and boom strut mount will have to be worked out, 26mm to 40mm lon get struts should get the mount where I want it.
I have trimmed the tail rod guide on the H-fin/strut mount in favor of a Lynx guide, the new stretch will have 2 as they are quite light.

It might look cooler or longer w/o the struts, I will probably opt for struts with dual bracing unless it starts getting too tail heavy.

Bolt on the thinnest, skinniest, lightest set of 500mm blades I have
At this point a maiden and round of testing is I order
Adding the 80 amp esc, really nothing special here I will gain 20 amps of power handling and Data Logging, and loosing Active freewheeling.

The motor is 42mm wide which puts it just a tiny bit to wide to fit between the lip of the frame halves, also the Shaft is a bit long. My plan is to space the motor down securely by adding an additional factory motor mount under the existing one and run all 4 motor bolts through both mounts.
At 600kv and 1500watts, we gain 200 watts (on paper) and the ability to make use of larger pinions.
I say on paper because when you bolt up a Scorpion 3026 or 3226 you know just what you are getting. When you fire up a off brand motor yon really can't be assured of accurate KV rating, Power handling, efficiency, or what will happen if you push a little too hard

That said the motor I ended up with is rated for up to 7s 1500watts, in this case I plan to run both on the data log esc to try to get an glimpse of what each is doing.
Should be interesting.

[deebee]

Here it is at the end of stage 1, lengthened boom, belt, tail rod, and added 500mm blades.

The blades had a 4mm brash bushing in place on the root, I used 2 3mm id X 4mm od bushings from a 3rd party thrusted tail kit, trimmed to 10mm length, to bring the hole down to fit the stock 3mm blade bolts.



testing today....
Edit:
Didn't get to really fly today, my camera (woman) backed out. I did test COG, and get in a quick hover at 1800rpm. With a 2600 45c Gens Ace and Poly Shamu canopy it was a little bit tail heavy. A 3300mah or 4000mah Lipo and a standard FG canopy should balance it out nicely. From just a quick hover it seemed a little lighter than before. A pitch pump or 2 at this rpm left me unable to notice any signs of additional loading, and the tail held about the same as with 470mm blades.

Looks like it has plenty of room to clear another 15 to 20 mm of blade main or tail. Maybe more.

Next mods, will include possible lengthening of the boom supports, working out best tail blades to use, and addressing any COG or strength issues.
The motor which I plan to add in the final step is a bit heavier and may help COG, but also may negate the benefits of 500mm blades.

I am dying to actually fly, the wife promised to let me make up the time I lost today! So hopefully I will get to try it out 2 morrow in the am. At this point I expect that running 500mm blades, although different, may not necessarily be any better than running the stock stretch.