Lightweight 250 pro dfc

[Phil79]

Out of topic question,

what head speed are you running for sport flying? or what hs you will recomend? im geting 5000 rpms at full throttle! but i just want to do sport flying.

[bmc76]

I've never put a tach on it, I run stock gearing with 90% in iu1 and 100% in iu2. Even after calibrating throttle max motor rpm for me is still around 81%, I lower my throttle channel endpoint to match.

[helimaddness]

Thanks for the thread. Very interesting read. Mine is a total porker and suffering from a heavy head. I wont my 250 to have its place in my fleet as it is so easy to travel with compared to the bigger helis but just hate the way the cyclic feels because of the weight. Exactly what you have described.

I have a questions.

I had some Emax servos but after problems I changed to MKS which are great but heavy. Turned out the problem in the end was 3GX related. (again) Have since moved to Kbar (vbar clone) and its sorted. Now to get the weight down.

With the emax servos you cant get the horn very close. On the MKS I can get them much closer. Even with them I am on the limit of the "happy range" for the kbar setup. Move the horn out and the setup numbers are way small. Lose all the resolution.

Guess you just dont worry about that ?

Cheers

[jypt01]

Originally Posted by helimaddness

With the emax servos you cant get the horn very close.
Cheers

Have you tried using the longer ball connectors?

[helimaddness]

Originally Posted by jypt01

Have you tried using the longer ball connectors?

Nope didnt think about that. Any idea on the part numbers for them? Assuming longer on the swash so can be shorter on the servo arm?

Was half thinking about using aeroplane clip on ones that clip either side of the servo arm The standard ones are kinda at a funky angle as well. Longer on the swash would help.

Cheers

[jypt01]

Originally Posted by helimaddness

Any idea on the part numbers for them?

Linkage Ball A(0#x1.8) x 2 - H25108

[helimaddness]

Originally Posted by jypt01

Linkage Ball A(0#x1.8) x 2 - H25108

Thanks for that. Makes a lot of sense.
I noticed after checking more the elevator is a mm or so further away from the main shaft. So adding longer ones to the front will make the front further from the main shaft from the elevator. I guess I can just trim out my swash travel in the Kbar software. I actually had to make a small adjustment before to get full pitch climbs level.

Cheers

[helimaddness]

so have ordered some Emax ES08 plastic servos. I had some before and they seem ok. Readily available here and cheap. will bring my porker down about 25g. Currently 366.

Has anyone tried a 5g servo? If the 8g ones can work on a 450 then maybe the 5g ones can work on a 250? Might be worth a shot?

Model.: DM-S0050
Weight: 5g
Size: 21.5 * 11.6 * 18mm
Speed: 0.08sec/60degree 4.8V:
Stall Torque: 1.1 kg / cm 4.8V:
Working voltage :4.8-6Volts
Cable length: 15cm
Compatible with Futaba, JR, SANWA, Hitec other well-known remote control system.

Also what about changing to a carbon boom and leaving off the boom supports.? The booms are fairly short and stiff maybe dont need ?

Cheers

[im2tall]

I just PM'ed a fellow member a couple of weeks ago about the boom supports,because he used to fly without them when he had a 250,and he told me they weren't necessary because the tail is stiff enough! I've since removed mine while I rebuild! I should know by next week when I do my test flights with new equipment!

[helimaddness]

Originally Posted by im2tall

I just PM'ed a fellow member a couple of weeks ago about the boom supports,because he used to fly without them when he had a 250,and he told me they weren't necessary because the tail is stiff enough! I've since removed mine while I rebuild! I should know by next week when I do my test flights with new equipment!

Cool let us know how you go. I had a bolt fall out of one the other day and didnt notice until I landed.
Also keen to try the 5g servos. Those ones above are 1.1kg so I would think plenty for a 250. Might just have to make a mounting plate up for them.

Cheers

[scott s]

These at 5.8 grams might be a better choice than above. Digital and 333 hz capable for the tail also. A mounting plate or some kind of extension to the stock frame mounting points will definitely be needed but probably enough torque for the cyclics on the 200mm blade trex. Metal gears!!
If align was smart they would make servo adapters or change the frame to accept a smaller lighter modern servo. This heli does not need 450 size servos LOL!

http://www.ltair.com/index.php?route...product_id=126

[helimaddness]

Originally Posted by scott s

These at 5.8 grams might be a better choice than above. Digital and 333 hz capable for the tail also. A mounting plate or some kind of extension to the stock frame mounting points will definitely be needed but probably enough torque for the cyclics on the 200mm blade trex. Metal gears!!
If align was smart they would make servo adapters or change the frame to accept a smaller lighter modern servo. This heli does not need 450 size servos LOL!

http://www.ltair.com/index.php?route...product_id=126

Wow they are little rippers. Light fast should be strong enough and metal gears at that weight. I was thinking cutting a square of credit card size plastic out and gluing the servo in to full the gap. I guess that will lose a gram or to.

Have just ordered some Emax ES08 plastic gear ones as only a few bucks and 8.5g down from the 17.45g MKS ones I have in there now. Will save a fair chunk. Was going to leave my MKS95i on the tail but maybe i try one of those little ones out. Would save another 11.65g on that alone......

Wow my 250 is about to go on a 10% weight loss diet with servos alone.

Now to really start looking :-)

[Miracle Boy]

Hi bmc76,

I've got hold of 3 x Ds76 and 1 x DS76T servo's, What BEC voltage are you running the ESC at? With the stock blue or yellow ESC re-flashed with BLHeli code, can you still change the BEC voltage?

Thanks!!

[bmc76]

I have the carbon boom and plus canopy on order from Amain, the talon 15 is preordered from tower. Below the rest of my planned changes are listed. 3 down, 2 to go.

Estimated flying weight is 298.8 grams after all changes are done, this is without adding any plus plastic parts, just the canopy, lighter servos, lighter boom, lighter gyro/rx, lighter esc with sufficient bec, and trimming wires.


talon 15: -8 grams
plus canopy: -6 grams
carbon boom: -1.5 grams
zyx-s2 w/sat: -4 grams
trim servo wires: -1.5 grams.

[bmc76]

Originally Posted by Miracle Boy

Hi bmc76,

I've got hold of 3 x Ds76 and 1 x DS76T servo's, What BEC voltage are you running the ESC at? With the stock blue or yellow ESC re-flashed with BLHeli code, can you still change the BEC voltage?

Thanks!!

5v, I don't remember seeing a voltage switching option in blheli, but I think it's been added, may check with Steffen.

[Argypak]

Hey guys, I'm using the DS76t an d noticed that my sbec is outputting 5.5 volts.
Do you think its necessary to step down?

If so what sort of diode do I need? Volts, Amps, Type

Thanks in advance

[jimmy77611]

I'm running my ds76t at 5.5v...been good for a bunch of flights.

[Argypak]

Thanks, but I can see a slow death for that servo if I don't step down


Sent from my iPhone using Tapatalk

[Yfbb]

Originally Posted by helimaddness

Wow they are little rippers. Light fast should be strong enough and metal gears at that weight. I was thinking cutting a square of credit card size plastic out and gluing the servo in to full the gap. I guess that will lose a gram or to.

Have just ordered some Emax ES08 plastic gear ones as only a few bucks and 8.5g down from the 17.45g MKS ones I have in there now. Will save a fair chunk. Was going to leave my MKS95i on the tail but maybe i try one of those little ones out. Would save another 11.65g on that alone......

Wow my 250 is about to go on a 10% weight loss diet with servos alone.

Now to really start looking :-)

I would leave the 95i on the tail. The extra authority is worth the 14g IMHO. The cyclics can be weaker, but the tail on a 250 should not be skimped on.

[helimaddness]

Originally Posted by Yfbb

I would leave the 95i on the tail. The extra authority is worth the 14g IMHO. The cyclics can be weaker, but the tail on a 250 should not be skimped on.

I had all sorts of tail problems in the beginning so hear where you are coming from. In the end the final fix was changing from 3GX to Kbar.
Have swapped the cyclics out so around the 340g mark so a lot better but still ways to go. Have got one of those light weight servos coming so will do some flights as is then try swapping to it and see the difference. If the tail is a problem can always go back.

Want to try and undo some of the tail mods to work out how much of it was caused by the 3GX crap gyros. Was going to try going back to the bigger tail blades as well.

Where so the light weight canopy's come from ? I was thinking of having a go at plastic molding one. Looking on youtube vacuum molding is not impossible.