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View Full Version : Ever heard of larger servos in a 250?


B2TheEYo
12-24-2009, 12:01 AM
So, no one scold me or think I'm some whack job, just curious. We all know the 250 accepts 9G servos (one of the ways of describing them), the same ones we toss in our common 450's. Question is, anyone ever heard or seen bigger servos used?

Look at this as "building up the momentum" or market research... ;)

May be useless, maybe overkill, nonetheless... It'd be unique.

heli-on
12-24-2009, 01:33 AM
Sub-micro is what is used in the 250 & 450. You'd be faced with enough of a challenge trying to fit micro-sized in a 450. Therefore, it'd probably next to impossible to fit anything larger in a 250. Have you ever seen how little amount of space there is between the motor pinion and the lower servo? Not sure why you're asking this question. If sub-micro works well enough in a 450, why would a 250 need larger servos?!?!?!?! :confused:

B2TheEYo
12-24-2009, 03:20 AM
Yup, quiet aware on the size challenges and the servos being more the adequate for the job, worked with so many 450's, where I started at, this is my first 250. ;)

More or less was just curious if I actually just did a first or if this has been done before is all. Dumb founding as to why, but hey, when the opportunity strikes - right? :YeaBaby:

I just obtained my 250, and have all the electronics for her, besides some cyclic servos. I'm in a bit of a finacial slump with xmas being day(s) away among the crappie economy, so blowing $90 on three GOOD servos isn't a option for the time being (I'm a do-it-right kinda guy with electronics, I don't like to use "value" equipment). Since I have a whole new upgraded carbon set coming, which is thicker than the factory carbon, I decided to try out a little idea I had in the back of my head. I have two spare sets of high-end cyclic servos for my 500 laying around, their identical to the same servos in 250's and 450's, just a bit bigger in length and depth.

So I did some modifications. Perfect fit turns out. No weight issues or power issues to be concerned about and the everything is still mechanically and structurally sound! :D

I'll be maddening her tomorrow and shall report back.

Crazy sure, but hell when you can save a wad of cash and have the fun of experimenting, why not?

If all works out, I'll be buying some carbon plates and copying the original top halfs into my 3D suites and modifying them for the larger servos and get them cut out at the flow-jet. :D

heli-on
12-24-2009, 09:14 AM
:Pics

Mikej
12-24-2009, 09:32 AM
Sorry - can't help it, got to respond :tongue:tongue:tongue

so blowing $90 on three GOOD servos isn't a option for the time being (I'm a do-it-right kinda guy with electronics, I don't like to use "value" equipment).
I'm not sure how you can claim to be a "do it right kinda guy" when you are suggesting using completely inappropriate servos :YeaBaby::YeaBaby:


I have two spare sets of high-end cyclic servos for my 500 laying around, their identical to the same servos in 250's and 450's, just a bit bigger in length and depth.
So identical except for being longer deeper and heavier :confused::confused::confused:

So I did some modifications. Perfect fit turns out. No weight issues or power issues to be concerned about and the everything is still mechanically and structurally sound! :D
Is this on a 250 or a 450 - for a 250 low weight is key to getting good flights characteristics - with this much extra weight you would probably need the 2000maH battery that the guy in the other thread is using :YeaBaby::YeaBaby::YeaBaby:

As heli-on said :Pics

B2TheEYo
12-24-2009, 10:18 AM
Mike, honestly not thrilled with your comments in some ways. I almost get the sense you posted to only poke fun at my writing that I did at 3AM, which is a bit of a buzz kill to be perfectly honest. So hold off on scrutinizing everything in such a literal way and read below so you understand a bit better. :cheers

I'm not sure how you can claim to be a "do it right kinda guy" when you are suggesting using completely inappropriate servos :YeaBaby::YeaBaby:

Never seen a mod that was "by the book", somehow you forgot what the subject of this whole deal is? I am a do it right kinda guy, I don't believe in cheap electronics or shotty setup. Do it right the first time by buying quality not quantity. :thumbup:


So identical except for being longer deeper and heavier :confused::confused::confused:

If you've ever worked with a verity of servos you'll know plenty of them are very different in form-factors. IE, some are a very large bold rectangular shape, where as some are a more narrow rectangular shape. These servos are identical in form factor to the original ones, just marginally wider and deeper... Hence why I said the same "size" essentially, but very loosely put.

Maybe a picture might give you an idea of the point I'm trying to get across..... :roll:

http://www.helidirect.com/images/servos/hitec/hrcm1008.jpghttp://www.helidirect.com/images/servos/hitec/HS81.jpg

These larger servos I'm using are only weighted 5g heavier than the HS-65MG's many others use in 250's and 450's. So weight is not an issue, especially when a Scorpion will be going under the hood soon. :D



Is this on a 250 or a 450 - for a 250 low weight is key to getting good flights characteristics - with this much extra weight you would probably need the 2000maH battery that the guy in the other thread is using :YeaBaby::YeaBaby::YeaBaby:

It's obviously a 250, why else would I post it here! :D

Something in that case might be a possibility, sure. Never said it wouldn't be, more or less I just asked everyone if this has been done to know if I'm the first crack-head or not. But hey this is all part of the "creative process", if it works, fantastic, if it doesn't, I'm not at a loss, at least I tried something different and had a good time doing it. Right?! :D

Having said that, the weight of the model is actually not all that heavy compared to those using Align nylon gear'd servos. We only have 15g's added to the whole model, that's less than the weight of all the CNC frame fittings and bottom tray majority of people commonly toss on and upgrade to and have zero problems flying with.

But, I'm heading out to dial her tail and cyclic in and maiden her, I'll report back on how it all goes and add pictures! :D

Merry Xmas guys! :D

Mikej
12-24-2009, 11:31 AM
Too right I was poking fun :lol::lol: Didn't mean to upset you though, all done in fun.

I have HS-82s on my 500 and know how big they are - I just don't get how things can be identical but different in a number of significant ways.

Good luck with it - looking forward to seeing the pics.

Cheers,
Mike.

B2TheEYo
12-24-2009, 11:51 PM
It's all good Mike! I sometimes have a difficult time grasping if people are doing things just for kicks and giggles or just to be a arse. LOL! I kinda expected to flanked with some very heated comments. Luckily, nothing bad. No no, didn't mean they were identical in every way, just form-factor. Seems to be quiet a verity of them!

Anyways, I flew the 250 today, the maiden flight! Flew great not as squirrely as I actually thought it would be. It was quiet docile but responsive when needed. Kinda dumped it twice into the snow, no damage, so I love this thing already!

Photo's will follow, I'm just cleaning it up now, did some more modifications, now that I know the concept works, I can push through to working on a set of properly cut frame sides, these ones I cut with a chainsaw file since I don't have a Dremel handy. :P

B2TheEYo
12-27-2009, 04:52 PM
Hey guys, here are the pictures. Flew her again tonight after dialing in my entire setup and wow, this thing fly's as nice as any 450 I flew or owned. The roll rates and punch-out's on this baby are out of this world, clearly there isn't going to be a weight issue of any sort!

Anyways the mod looks a bit incomplete, as it's still a prototype or more a less a "proof-of-concept". I got a sheet of carbon fiber coming, 1.5mm thick (thicker than stock) that I'm going to get the final frame side designs I've done up in CAD cut out by a flow jet. It'll look factory then and not so much a homebrew mod. :D

I was a bit mad at myself when I was filing out the cuts with a chainsaw file (Dremel wasn't handy) I broke off the tiny peice along the front servos. None the less, when I just fit the servos and didn't secure them with screws, everything was VERY rigid and strong, no flex what so ever. Now that everything is fastened it's a solid as can be!

Definitely a fun little project, saved myself $90+ in getting stock fit servos by using these new 82MG's I had laying around and killed some time doing it. Only cost me $13 for the sheet of carbon fiber on the way.

Enjoy.

http://www.helifreak.com/attachment.php?attachmentid=130944&d=1261954076
http://www.helifreak.com/attachment.php?attachmentid=130945&d=1261954076
http://www.helifreak.com/attachment.php?attachmentid=130946&d=1261954087

heli-on
12-29-2009, 12:18 AM
Good job. So you're saying you're not getting any weird cross-cyclic interactions. The geometry of the servo links looks to have changed significantly.

Vibrations are pretty high on the 250 and if you're servos are touching, I can see it being an issue over time. There's nothing holding the front of the forward-most servos, either. Looks strange. Like something in WIlly Wonka's office.

How's your clearance with the pinion. It's extremely tight, along with routing the servo wire. Looks like you lucked out and the wires come out on the opposite side so you didn't need to route them on the outside of the frame.

sethf8403
12-29-2009, 01:49 AM
wow those things are huge! to be honest i woulda just waited for some hs65's...those giant servo's look like they are hog piling your poor little heli....no offence, i just don't like the way they look on it...

very ingenious though, but i don't think it's really going to catch on, lol

Tomstoy
12-29-2009, 02:43 PM
Looks good, Mike! I think you're crazy, but that's nothing new, LOL. Like you said, it's all about the experience. If it don't work, find a way!

So what do you have your swash mix at now? I'll have to check and see what I have mine set at.

How's your tail working out. When I built mine I wasn't impressed. You've seen the mods, now I'm so damn pleased.

Keep her in close, buddy. I only take mine out about 1/3rd the distance I do a 450. Not saying that stops the crashes, it's just too much fun to experiment with.

B2TheEYo
12-29-2009, 06:35 PM
Thanks for the comments guys. :D

The swash interactions are just as they should be, with or without the mod, everything operates quiet well. Though as has been noticed there is a bit of a slant on the links, not all happy with it but after all this is a really light and small model so it doesn't hold much up to being an issue. More or less just something you frown upon or live with. They run perfect from the front, bang on straight up but from the sides you see the noticeable slant.

But the servos are very secure, the bottom front one is held in by the material coming up for the battery tray to secure too, the top well, it's so snug it doesn't move. You can practically get away with not securing the servos with screws. Which is what I was after - a tight fit. this way the frame has a bit more stiffness. I do hate the fact I messed up when modifying the frames and broke off that front piece as if I didn't it would still be there but that what happens when you use a chainsaw file in the absence of the Dremel.

As far as vibrations, definitely notice this model has horrible vibs. Though I've isolated it to the blades, nothing else. Without them the model has no more vibrations other than from the motor running, which isn't unusual. I'll be trying out different carbons to see if I can get rid of them, so far, not an Align carbon fan, or I just got whacked sets.

Tom, the tail felt fine when I maidenend and dialed it in. In fact it felt just like my 450, but the wind can do some wild stuff to this poor little guy.

I was going to take her out for a good stick'bang'n but it's so gusty and stormy out.. Sigh. :P

Tomstoy
12-30-2009, 02:05 AM
I hear you on the vibes. Mine started out that way too. But it wasn't the blades, it was the lack of stiffness using plastic instead of metal. Once I got rid of the plastic the frame became rigid and my vibrations were history. I wonder if you aren't experiencing resonance too?
The stock lever arm at the ball is a lot of slop. My servo got so hot from overworking the tail that I had to do something. Once I upgraded to the MH slider the slop totally disapeared. I highly recommend this.
The gyro I moved to the top of the boom. I just couldn't get over the idea of hanging the gyro on a plate suspended. I have no Idea if moving helps it or not, nor do I care. It bugged me so it's gone.
After all that I was left with a machine that is rock solid, can piro at blinding speeds and stop with out any bounce back. It holds every bit as well as my larger birds not only in the tail but in it's stability.

Enjoy the little bugger, my friend. Stay warm.

RyuuChi
12-30-2009, 03:08 PM
Sub-micro is what is used in the 250 & 450. You'd be faced with enough of a challenge trying to fit micro-sized in a 450. Therefore, it'd probably next to impossible to fit anything larger in a 250. Have you ever seen how little amount of space there is between the motor pinion and the lower servo? Not sure why you're asking this question. If sub-micro works well enough in a 450, why would a 250 need larger servos?!?!?!?! :confused:



I'm not trying to nit-pick, but based on the way most sites (well, readyheli anyhow) list their servos by size, the hs-65 (recommended servo for the 250) is classified as as a micro and servos the size of the s9257 are listed as mini and the 9254 as full sized... is there some way that this is wrong??


also, nice build. definately overkill and may affect the flight characteristics a bit, but at least its a clean looking install. maybe i'd recommend trying to find a way to stabilize the front of the front cyclic servos though.