SIG 51.5in Somethin’ Extra

Introduction

When a fellow I’ve know for decades reached out inquiring about servos for a SIG 51.5in Somethin’ Extra I was delighted to help. First, because it offered an opportunity to catch up, and second, because he’s an experienced guy. I felt honored he was seeking my advice. Here’s what I told him.

Bottom line? This is an exceedingly fun to fly model airplane which can be set up one of several ways, depending on the goals and equipment. One sees to using a 2-stroke nitro fuel .46, or maybe a gasoline powered .60. Another school of thought sees you relying instead on a 4-stroke .56 engine. And yet another would see it powered by an electric motor with a 6S4400 propulsion pack.

Obviously, the .46 2-stroke could be a .40 through .55, and the 4-stroke could be a .48-.72, the baby gasser could be an 8cc instead of a 10cc, and the electric could range from a setup for a 10in prop through a 16in prop with 3300-5000mAh pack.

Which is best? It depends on you, your needs, desire, and budget!

Servos

So I’m going to lay this out in the language of good, better, and best but this is only true insofar as what suits you. For example, our DS90DLHV is the recommended servo for ‘good’, but the mere fact it’s only $30 a pop may immediately move it into the ‘best’ category for you if money is tight.

Saying because we’re all different, how ‘I’ sort them matters not in the slightest because I don’t know you. Honestly? The only thing that matters is you, and your needs. Moreover, we’re using the same potentiometer in all of them, the 1-million cycle Nobel 1mc so there’s no difference in centering performance based on the price you pay. See what I mean by . . . it depends?

Whether you’re selecting Herb’s ARF version or building his kit version affects things, also, because with the ARF, the size of the servo mounts are set in a Chinese factory whilst with a kit you can make adjustments while you’re building it.

And no, not than an experienced modeler can’t adjust the servo mounts in ARF, just that this adds to getting it ready for flight. Might ‘still’ be what you do – but – once again, it depends! So there’s no one right answer. Let’s explore and see what’s what.

Background

I mentioned Herb. He’s the guy who bought SIG from Hazel. Then a few years ago someone made him an offer he couldn’t resist and he sold it to them. In a nutshell (because the details are not germane), mistakes were made and he bought it back again.

So with Herb at the helm, things at SIG are going gangbusters, once more. And lest you think this guy doesn’t know jack regarding this business, know this; this is the fellow who owns Evergreen Scenery and Plastistrut, both super successful companies in the model railroading community. Believe me, SIG is in good hands once again.

Servo selection should be next but actually, first I’m going to touch on pilots because ‘who’ you are and ‘how’ you fly affects the decision regarding which avionics are best for you.

Pilots

In our experience, there are three basic types of pilots. Of course there’s an infinite number, but if we slice and dice to put them in three buckets, they’re the club pilot, hotshot, and hooligan.

And look, guiding you would be much easier if we were mates. Like if I knew how you fly because we flew together then I could maybe say, bluntly, ‘You’re never going to perform a crankshaft, forking over $80 for DS205 brushless mini-class servos is stupid because the only place you’ll feel the performance difference is in your wallet!’

Or maybe, ‘I’ve seen you fly inverted on purpose once, and I could hear your knees knocking, those $30 DS90DLHV standard-class hybrid-servos are plenty good enough for what you do.’

But since we’re not mates, meaning I don’t actually know how you fly, then we have to trust you to be true to yourself in making the decision. So the best ‘I’ can do is try and help you see yourself more clearly.

Club pilot

The club pilot is what’s often referred to as a gentleman flier. Pilots fitting the description of ‘club pilot’ encompass a wide range of skills.

For example, on one end of the scale are pilots like the one in the above photo. These are the ones who fly a lot. They burn lots of fuel. They know everybody, everybody knows them, and they’re totally solid pilots who appreciate good centering and saving money.

Then there are those who don’t fly as often. They fly fairly high and rarely fly inverted. They’re perfectly happy flying circuits and making the occasional low pass and on their way home at the end of the day, quietly utter a sigh of relief and reflect on the successful landings.

This fellow flies once or thrice on any given weekend, and enjoys visiting most of all because for him flying is about the fellowship and a break from the M-F grind. It’s about the fun.

Then there’s an in-between type of club-pilot. Talking about pilots with solid technical skills. Talking about the über competent sticks who attend a lot of events, fly a lot, and for whom centering is supremely important.

Hotshot and IMAC pilots

All clubs have the guy who can competently perform 3-rolls down low. They’re considered hotshots pilots. Some like to show off, others just do their thing because it’s what they love to do . . . whether there’s anyone there to watch, or not.

And they’re such good sticks they’re asked to test fly for others.

But there are actually two types of pilots in this group. There’s the disciplined guy who practices several times a week and goes on the contest trail but flies a Somethin’ Extra for fun. Talking about the guy seriously into IMAC competition.

These are the guys at the very top end of the pilot skill set. They’re totally into performing maneuvers smoothly whose repertoire of maneuvers includes credibly performing many from the old FAI schedule.

Then there’s the guy who is an utter natural sticks. Now we’re talking about guys blessed by God himself with a talent that brings the show to a stop when they take to the sky. Didn’t get there without practice, but they make it look easy.

You know what I mean, the ones for whom folks stop flying just to watch as they performs crankshafts, rifle rolls, and wall maneuvers. Plus Harrier rolls within ten feet of the ground the length of the field!

They can do this with anything with wings, Somethin’ Extra included!

So bearing in mind who ‘you’ are pilot-wise, we’ll make equipment recommendations for your 51.5in SIG Somethin’ Extra. Just remember what Shakespeare said . . . to thine own self be true.

But first, let’s touch on budget.

Budget

After pilot type, budget is second on the list of considerations. Money lurks in every decision. Be one thing if we were all rich but the facts are money doesn’t grow on trees, so selecting servos involves a keen focus on what’s important.

I’m going to concentrate on three servos, one ranging in price from $30, through $60, to $80 (although I’ll mention others worthy of contemplation).

However, beyond servos, I’m also going to present servo arms for which you should budget because they’re not all the same. And the proper ones are crucial in achieving the proper setup. Yes, setup!

And we’ll lightly touch on stuff like getting enough juice to the servos. If you don’t, they just won’t function as designed. This last being true whether you use our servos, or opt for a competitor’s because we’re not dealing with opinion, but with physics, instead.

These things aren’t expensive, but they’re money out of the budget.

Goals

After pilot type and budget, third on the list of considerations are your goals. Every pilot is on an arc of development.

Like there’s the guy getting started with 3D who will put himself out there for two hours every evening on a simulator. Why? Because he’s seen YouTube videos of Jase and wants to reach for the brass ring.

Believe it or not, the SIG Somethin’ Extra is a good step on the path. Look at the sheer size of the rudder and elevator surfaces. This being the part of the horizontal stabs that actually move.

The elevator is easy 40% if not more, and the rudder is more than 50% so the model will react right NOW is you want to horse it around. Means you need servos that aren’t just powerful enough, but also capable of moving the surfaces fast.

Then there are guys who have enough stress Monday through Friday and fly a model like the Somethin’ Extra just for the fun of it. They love the look of a scale Extra but they have absolutely zero intention of ‘ever’ doing a Harrier rolls or Crankshaft maneuvers.

This circles back to budget and what I meant about being true to yourself because you may ‘choose’ to equip your model with our fastest servos, and long ass servo arms to impress the peanut gallery with 45° throws in the blink of an eye – but – if you never actually doing those kinds of maneuvers, then you’ll just be pissing away your money. Saying, choose wisely.

Note; I recognize for many of you it’s not so much because you can’t fly like a hooligan if you really set your mind to it (because you’re a decent stick and can learn, especially using a simulator). Suspecting it’s more like you’re not really into stressing over things and want the aircraft to perform realistic flight – more like maneuvers the aircraft would do at an airshow – instead.

Anyway, most serious of all are old IMAC pilots. These guys have stepped back from competing in pattern and these days are now just flying for fun – but – making serious demands of their equipment in terms of centering and repeatability (as if they were still on the contest trail) simply because old habits die hard.

And all of these different types of guys, each with their own goals, need servos that can take what’s dished out – and – get in return, equipment you can depend on.

Next we’re – finally – going to sort servos in terms of three broad categories of good, better, and best, and along with servo arms and extensions make equipment recommendations for your SIG Somethin’ Extra (or the Somethin’ Xtra the electric ARF version).

Equipment recommendations

For pilots who want the good stuff, but don’t want to spend stupid amounts of money, allow us to introduce you to the ProModeler DS90DLHV and DS180DLHV – both DL-series standard class servos.

Good – as in good enough for most

• Qty 5) DS90DLHV – 2 aileron, plus rudder, elevator, and throttle
• Qty 5) stock servo arms

Gooder (yes, I know it’s not a word)

• Qty 5) DS180DLHV – 2 aileron, plus rudder, elevator, and throttle
• Qty 4) PDRS101 heavy duty polymer servo arms
• Qty 1) PDRS105 throttle servo arm

To know the DL-series is to know there are five in the series, each as alike as peas in a pod but due to different gears and motors, outputting in a range of 90-360oz-in . . . and priced accordingly.

And here’s the thing, how do you know if one of these servos is right for you? Well, maybe the best way to figure this out is by seeing how an equivalent ProModeler servos compares to a very well regarded competitor, like the Hitec D645MW.

• matchUP: Hitec D645MW vs ProModeler DS180DLHV

So both of these cost $40, output 180oz-in, transit in 0.17sec/60°, but only one has stainless steel gears, meets eight MIL-STDS, has 13 seals and o-rings. We tend to think choosing the ProModeler is a no brainer (as we should since we’re the ones offering them to you) but everybody has to reach this conclusion on their own.

Note, the above benefits are ones you get across the entire DL-series. So in reviewing how these servos match up, you’re effectively also seeing exactly how a DS90 is made, as well as a DS130, DS270, and DS360 because they’re all pretty much the same.

And yes, implicit in this list is ‘gooder’ for you might be the DS130 or even the DS270. As always, it depends! So without reading the full matchUP article, let’s touch on a few things worth considering.

Gear train

At $30 for the DS90DLHV, and $40 a pop for DS180DLHV what you get are servos with the most durable and vibration resistant of all gear trains, stainless steel. And not just any stainless, 330 for the bull gears and hardened 412 pinion gears.

Spot Welding

But there’s more because if you’ve been flying servos equipped with brass steel gear trains, let me show you what you’re gonna get with these rugged servos, instead.

Part of making us different, the whole reason we give engineering a free hand, and behind ‘why’ for contracting officers and industrial users selecting ProModeler are thoughtful touches. Like spot welding the 6/7 compound bull and pinion gears together to reinforce them.

Or as has been observed, God is in the details

Bronze Bushings

DL-series servos also feature a rugged impact resistant upper case. One that’s injection molded of Nylon 6.6 fiber-reinforced polymer. This is the same kind of stuff used in a Glock handgun frame – and for pretty much the very same reason . . . lightweight and tough!

Moreover, to give you a long service life, one easily rivaling a pricey all-alloy case (whilst keeping weight low), and unlike others their class, you get bronze bushing reinforcing the gear shaft pockets.

13 Seals and O-rings

Another thing you get with DL-series servos, important because they’re mounted external to the aircraft, are 13 seals and o-rings. This matters not just because of the oil in the exhaust due to the premix, but because so many of you love to fly with smoke oil.

Saying this is also a big deal.

Million-cycle Pot

Also worth noting is this; you get the same 1-million cycle Noble 1mc potentiometer in a $30 servo as in our $100 and $140 servos. Means exactly the same great centering performance.

By the way, we’re occasionally asked why we don’t use a Hall Effect potentiometer like some newer brand imports. We don’t for good reason and to keep from going into a dissertation, maybe just review this brief article and learn more:

• About pots vs Hall Effect sensors

Heat Sink Center

So it gets better as you consider using DL-series servos because you also get a center case CNC-machined from a solid billet of 6061-T6 aircraft aluminum. What for? Simple, to give you better cooling.

As for when this is super important, it’s when your servos are working hard because heat is the enemy of electronics. Moreover, I suspect if you look at servos you already own, ones also equipped with alloy centers, what’s often missing are cooling fins.

This is a case where less is more because it’s within what we removed, excess aluminum by machining the fins, that you benefit. Point being, ProModeler servos use the center case as a heat sink!

Potting Compound

Something else you get with DL-series servos are how we coat the PCB with potting compound. This protects them from vibration and shock. It’s an aerospace technique, which flows and surrounds the surface mount components in sticky compound (which stinks to high heavens, and which we call monkey snot).

What costs about doing it is the time to apply – and – because we have to wait for it to cure. So time really is money during assembly. As for what’s in it for you, and why hobby grade servos don’t do it, just follow the Benjamins because unlike our direct business-model, their business sees a lot of folks wetting their beaks in getting servos into stores (e.g. the importer’s 15% cut, distributor’s and their 25% cut, and the hobby dealer’s 40% cut – all for just touching the servo and – for which you pay).

So back to the monkey snot; the end result of using it your servos are more shock and vibration resistant because of it. And what’s the alternative, doing without? This is what the hobby grade servos do.

Why? They’re rely just on the strength of the solder to securely hold delicate surface mount components like microprocessor, diodes, resisters, and FETs to the circuit board. This is a problem awaiting a ass to bite.

Saying there’s a reason the airlines, NASA, and the Air Force insist on potting compound within the avionics. And this is probably why you’d prefer your servos have it, also. Basically, solder easily fractures due to vibration.

Anyway, if you agree vibration is bad juju for your servos, then this matters! And it’s what engineering-driven means, and why modelers are switching to ProModeler.

MIL-STDS

Know what else you get with DL-series servos? Eight MIL-STDS.

Our principal customer insist on them and you benefit, too because we’re not building two grades . . . so you don’t pay a thin dime more!

What do you give up?

It’s reasonable to wonder, ‘What do I give up buying $30-50 servos?’

Maybe a lot, maybe nothing. Maybe nothing important to you. And probably less than you might imagine because it depends.

For example, while the DS90DLHV is fast enough for sport maneuvers like rolls, and snaps at 0.18sec/60°, they’re not quick enough for hovering and torque rolls where you need to really get into the range of 0.12-0.14sec/60° or faster.

But on the flip side, if these aren’t the kinds of maneuvers you fly, then spending more money is pointless, agreed?

Output Shaft Reinforcement

And while the DL-series are really good, they’re better now than when we introduced them. This, because back in 2023 we reinforced the DL-series around the output shaft with more material and switched from all-metal to all-stainless gears. Point being, we’re never standing still.

Eyeball the before and after to see how this iteration is stronger around the output shaft for our having modified the mold to increase the size of the ring of material supporting the ball bearing.

Better – intro

Nevertheless, there’s a reason why highly experienced pilots may be more inclined to fork over for different servo. And not necessarily more expensive. Different.

BUT you first have to look to yourself to assess your goals, needs, and budget because to the question; ‘Can I really use $30 servos and be happy?’ The answer is . . . yes, you can!

Like if you’re a sport pilot, or one who doesn’t fly a lot, then it’s crazy to be spending more money for servos. Especially when you probably won’t even notice the difference!

But whether the next set of servos we’re going to mention are right for is something of an open question. And it’s one with only one answer . . . it depends on you and how you fly.

So let’s look at what ‘may’ be some better alternatives servo-wise.

Making the better-list are our DS100DLHV and DS150CLHV micro-class servos. And what’s important to note is these are significantly smaller and lighter than standard-class servos.

Standard at the far right, micros are the ones second from the left.

Better

• Qty 4) DS100DLHV – 2 aileron, plus elevator, and throttle
• Qty 1) DS150CLHV – rudder (more knife edge authority)
• Qty 4) PDRS101 servo arms (or PDRS20-25T if you like good stuff)
• Qty 1) PDRS105 – arm (throttle)

Better-er . . . not a word, a concept

• Qty 3) DS150CLHV – 2 aileron, plus elevator
• Qty 1) DS150CLHV – rudder (more knife edge authority)
• Qty 1) DS100DLHV – throttle
• Qty 4) PDRS101 servo arms (or PDRS20-25T if you like good stuff)
• Qty 1) PDRS105 – arm (throttle)

Why micro servos? Simple, because the lighter the model ends up, the lower the wing loading, so the better it flies. Making the micros work is a bit tricky because the model is pre-manufactured with larger/heavier standard-class servos in mind.

Point being, you’ll have to adjust the servo mounts to fit the smaller servos. So in this next photo we see the standard servos installed within the supplied Somethin’ Extra light-ply servo tray.

By comparison, the micro servos are so small they’ll fall right through!

So making the micros fit can be, a) as difficult as cutting out the old light-ply tray using a #11 X-Acto (with a bit of patience) so you may fit a new mounting tray (or rails) better suited for micro servos, or b) as easy as CAing two short pieces of Popsicle stick at each end of the existing servo opening to bridge the gap. Macht nichts!

As always, the best depends on you and your way of doing things.

The trade off (beyond micro servos being quicker and costing more) is the gear trains are smaller and more fragile. Means exercising more care in handling the aircraft.

Like when getting the model in and out of the car, e.g. to ensure you don’t bump the control surfaces against the door opening. This, because it’s infinitely easier to inadvertently strip the gears because they’re so much smaller.

Still made of metal. Still plenty strong enough to fly the aircraft. Not strong enough for the ham-handed. Consider yourself warned!

So I’m sharing this photo to make a point, this fellow is a competitor. Flies his Curare on what’s on called the Senior Pattern Circuit. These are guys who recreate competition pattern class models from the 1960-1980s (befoer the FAI turnaround schedule came into effect).

These are models equipped with screaming .61 engines, retract gears, going 7-1/2 pounds and hitting 120mph straight and level. To say these guys are assholes when it comes to demanding the best in centering performance and precision is NOT an exaggeration.

Saying if micros are good enough for them, then you don’t need to fret about them being good enough for your Somethin’ Extra build. Especially if what you’re trying to extract from the model is going to see its performance benefit from weight reduction.

So in exchange for more money and fragility, with the micro servos you get a setup strong enough to fly the model very well ‘and’ reduce the overall weight a bunch. Lighter to the tune of maybe 6oz, which in this class of aircraft is a bunch!

When would I ‘not’ do this? Maybe if I were going to use a four-stroke or gasoline engine. These engines are so much heavier than a 2-stroke equivalent it probably doesn’t matter.

When would I definitely do this? Same reason, because these engines are so heavy it definitely ‘would’ matter.

Aren’t I speaking out of both sides of my mouth? Sort of.

The facts are, for a novice or sport pilot reducing weight and sacrificing durability likely makes zero sense. But for a more expert pilot, then these super light servos make perfect sense.

And we’re back to what I’ve been trying to tell you. The ‘best’ servo always depends on you and what you’re trying to get your build of this SIG Somethin’ Extra to do!

So next we’re going to delve in best, and with these we’re now getting into even more ‘trick’ components. Smaller than the micros?

Nope, larger? Confused? Don’t be.

we’re going to be depending more on mini-class servos. These are the one sized between the micros and the standard class. And making life easier when fitting minis into a Somethin’ Extra cut for standard class servos are CNC-machined alloy M2S mount adapters.

Best

• Qty 3) DS160CLHV – 2 each for aileron and elevator
• Qty 1) DS210CLHV – rudder (more knife edge authority)
• Qty 1) DS100DLHV – throttle
• Qty 4) PDRS20-25T arms (or PDRS15-25T if you detest touchy)
• Qty 1) PDRS105 – throttle arm

Best-est . . . again, not a word

• Qty 3) DS205BLHV – 2 each for aileron and elevator
• Qty 1) DS355CLHV – rudder (more knife edge authority)
• Qty 1) DS150CLHV – throttle
• Qty 4) PDRS20-25T arms (or PDRS15-25T if you detest touchy)
• Qty 1) PDRS105 – throttle arm

Pluses and minuses

So what do you get, what do you give up? To begin, the DS160 and DS210 are often used in 3D models of the class represented by AJ Models, Extreme Flight, and Pilot RC.

So here’s the thing; whilst the Turbo Raven (below) spans 69in, area and weight-wise it’s not a lot different from a Somethin’ Extra. What’s more, propulsion-wise it uses a 6S4400 pack and is pretty much the same type of electric system you may choose to fit to an electric version of the Somethin’ Xtra ARF.

• EF 69in Turbo Raven servos

So depending on the pilot, these same servos may be perfect for your model, also! Especially if the thought crosses your mind the next aircraft you want is one of those specialist-type 3D models in which case, presto . . . you already have the servos!

No clue what the numbers and letters mean? No need for Cliff Notes:

So while you get all the goodness of a DL-series, the price for minis are higher and even more so if you opt for alloy case with brushless motors. What do you get in exchange? This is what’s better;

• 4X more durable alloy case versus polymer
• 255% more torque in going from 355oz-in to 100oz-in
• 246% increase in transit speed from 0.052sec/60° to 0.18sec/60°
• 5X longer motor life and cooler operation with brushless motor

Final thoughts

Allow me offer a few final thoughts. The right servo for you is a reflection of yourself, your goals, your dreams, and your budget. We put a better grade of servos in your hands. But nobody can make you buy them. This you decide for yourself.

Any questions? Feel free to reach out, we’re readily available;

• Telephone: 407-302-3361
• Email: info@promodeler.com

. . . maybe together we can suss out what’s best for you!

I’ll close with this, one thing’s certain, best is a race that’s never finished. Best right now? ProModeler, but far from David vs Goliath, we’re more akin to a flea on the elephant’s back in this battle.

Means we need your help. Presuming you like our servos, then do us the favor of taking one to a club meeting. Pass it around. Maybe even pull out a 1.5mm Allen driver and open it up – you’ve seen how they go together, there’s nothing to be afraid of. And please, show them to a pal.

But most of all, kindly grace us with a photo sharing your thoughts. What for? To put on the website, and within articles like this. Basically, for telling the next guy what you like about our servos.

We’re Jones-ing for photos like this one because your favor is priceless and can’t be bought. We know this. So do others.

Last thing

Have you enjoyed this? If you like reading and are interested in learning more, then maybe find time to review more articles like this;

• On the batteries John prefers using
• About pots vs Hall Effect sensors
• On selecting battery packs
• Pro tips for improving your ARF
• Amazon servo vs DS505s
• Why’s my pack got two JR-connectors?
• Rip Van Winkle, on returning to RC
• How to guide a rocket using servos
• Phoenix Models 70in Strega guide
• Advantages of pull-pull via pulley
• Bret Becker: Mr. Top Gun
• Will ProModeler servos work with NiCds?
• How to determine flight time for a 2S850 LiIon
• Hangar 9 60cc Pitts S-2B servos
• Fear of loss, or how to stack the odds in your favor!
• When LiFePO4 is mistakenly charged as LiIon
• Idle thoughts regarding chargers

. . . and hundreds more. Best part? They’re all free!