Sig Distributed Herr's Lil Somethin' Extra ARF, Electrified ala MP JET Power - RC Groups

Sig Distributed Herr's Lil Somethin' Extra ARF, Electrified ala MP JET Power

Mike Llewellyn has a blast exploring Herr's little brother of the Sig Somethin' Extra ARF, including electrifying it. He finds the little extra to be so much like its bigger brother, he finds himself confusing them!

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Wingspan:36.5" 927mm
Wing Area:344 sq. in. 22.2 sq dm
Weight:Advertised glow 25.4oz.(720g) Actual 29.6oz
Length:34.75" 883mm
Wing Loading:12.4 oz/sq. ft.
Servos:2 Hitec hs55's aileron and 2 GWS Naro +BB
Transmitter:Airtronics RD8000
Receiver:Hitec Super Slim 8
Battery:Tanic 2220 3s LiPoly
Motor:MP Jet 28/10-13 Outrunner
ESC:25 Amp Cool Running ESC
Manufacturer:Herr Engineering
Available From:Sig

I must admit that the Herr Engineering kit line has always impressed me. I was thrilled to learn they were adding an ARF to the line. I was especially excited when I learned the ARF would be the little brother of the very popular Sig Somethin Extra.

The Herr Little Somethin Extra and the Sig Somethin Extra both share the rough lines of the Extra 300s full scale aircraft. But it was easy to see this was no scale ship, starting with the thick wide wing.

I placed an order for the Herr Extra from Tower Hobbies and was happy to see the email indicating mine had shipped. My ARF arrived in great shape and I could immediately tell this was going to be a quick assembly, and a very easy conversion from glow to electric.

Kit Contents


Assembly is right – this ARF came with everything I expected and it was nearly completely assembled out of the box. I fully anticipated a 10 hour build time, including the conversion. The manual was the standard step by step with black and white photos. It matched the expected Herr/Sig quality and it was very complete and thorough. They also included this nifty exacto knife holder…


The wing was fully assembled -- unlike its big brother, the Little Extra had a one piece wing. It was factory joined, so the only work necessary was mounting servos and installing the ailerons. Every surface on the Herr Extra had slots cut and hinges ready for thin CA glue.

I did learn one trick, and I must admit it was not easy to do that after 27 years in this hobby. The standard CA type hinges that were included had a cut slot down the length directly in the center of the hinge. This allowed me to slide some cardstock into the slot in the hinge and when I slid the hinge into the corresponding surface it kept the hinge from going too far into either the wing or aileron. I simply slid the aileron into the wing, and when I was satisfied with the surface alignment, I removed the card stock and applied thin CA. A great idea that worked perfectly. I can not tell you how many times I have worried that the hinge was inserted too far into the wing or aileron.

Wing servos, one for each aileron, were installed using a plastic cover and hardwood blocks. This had a much cleaner finished look than the top of a servo sticking out of rib bays.

The wing dowels required very slight rounding before the wing fit in the saddle with a snap. The fuse had the blind nuts for the landing gear and wing installed. The included 4-40 single nylon wing bolt fit without adjustment. The holes were all predrilled and aligned! Anyone who has built an ARF type kit with misaligned holes knows the pain that causes. Hats off to Herr for spending the time necessary to make a straight and aligned ARF.

Two and a half (2.5) hours and the wing was completely done. This was going to be a quick build!


After the wing was complete I glued the tail surfaces on. The elevator slid into the rear of the fuse, and it fit perfectly in the provided slot. The rudder keyed into the elevator for a super strong joining system. Once again the fit was snug and perfect. A quick addition of the tail wheel had the tail feathers done.

Total Time after the Tail – 3.5 hours.


Next I installed the landing gear and wheel pants. The pants were completely finished and ready to install, one screw installed them so they would be easy to add or remove at the field.

Radio Installation

I used GWS Naro BB+ servos for the rudder and elevator. Preinstalled plastic tubes in the fuse made the solid wire pushrods a snap to install. They even had a pre-cut exit hole in the tail of the fuse. I did deviate from the recommended method of installation by using Dubro Mini connectors. I am a long time fan and they make fine adjustment so easy.

A Hitec Super Slim 8 receiver was mounted in the area just in front of the pre-installed servo cutouts. This RX allowed me to use the dual aileron servos as flaps and ailerons.

I used the supplied horns (glue in type) and keeper type arms. They were all of good quality. The horns had spikes on them, but the pre-drilled holes in the surfaces did not allow the horn to be at 90 degrees to the surface. That was the only mis-alignment in the entire airplane. I simply redrilled the holes so they aligned the horns properly.

Total build time so far - 4.5 hours.


The attractive two finish colors arrived in Sig AeroKote Lite covering. When these ARF’s were built in high humidity countries and brought to lower humidity areas of the world, wrinkles developed. It was low temp covering so I used care when getting the wrinkles out.

Electric Conversion

The first thing I have always done when converting a kit or ARF to electric power was weigh everything. I liked having an idea of the estimated completed weight so I knew what power system to use. Here are the weights of various components of the Herr Little Extra:

All surfaces:2.1oz
Wheel pants:.8oz
Landing Gear (minus pants):1.1oz
Total of all parts:15.4

I was hoping for a 22oz AUW, but it was clear that would not be attainable. I was a bit disappointed by this, as the Herr kits use light balsa, not too much ply and are typically very light.

Power system

Due to the anticipated all up weight I knew my PJS 550e motor planned for this plane would simply not be adequate. So I planned on using my Mega 16/15/5 turn motor running direct drive for my first flights. I had selected the Tanic Packs 2220’s running 3s cells and a 7x5 APC-e prop for starters. When I attached that combination to my meter, it drew 24 amps at 3/4 throttle. That was well above the 20 amp maximum for the motor. I did not want the lack of thrust with a six inch propeller, so I decided a new power system was in order.

I wanted a power system that would produce and honest 200 watts at about 20 amps. A quick search revealed a motor I did not know much about. I decided on the MP Jet 28/10-13 outrunner motor, with the firewall mount option. This motor arrived quickly from Todds Models along with a 25 amp ESC from Cool Runnings ESC.

Tests on my new MP Jet 28/10-13 motor revealed the following numbers. As you can see it was going to need to swing a large prop to get the 200+ watts that I wanted.


With a completed plane that weighed 29.6oz, the 10x7 APC-e propeller should yield just about 116 watts/lb. That should provide excellent performance...let's see!

Motor mount system

The Herr Extra came with a beam type mount pre installed. I knew that I would have to remove it for the MP Jet motor. If I used another motor type I could easily have adapted it for a clam shell type mount.

Battery Tray

Decisions decisions. I hate cutting into new ARF airplanes. I also dislike taking the wing off for battery changes. I knew from my initial CG tests that the battery would need to nearly touch the firewall. With the battery that far forward I did not want to try to slide a pack into the nose of the plane. So, I opted for cutting a hatch for battery access.

To begin I cut away the bottom sheeting of the nose area. I was very pleased to see good quality balsa here and that they used plenty of glue on all the joints including the formers and sheeting.

I trimmed the F2 former in the middle of the tank section to allow for the depth of the battery and tray. To regain the lost strength of the former I installed a 3/8” square balsa brace on that F2 former. I also installed the balsa stick on the back of the firewall to support the end of the tray. I used a piece of 1/8” lite ply for the tray itself. I sized the tray so it would be the width of the pack, and just short of the length of the pack. That would allow easier fit of the pack between the landing gear mount plate and the battery tray itself.

For a more finished look I trimmed the F2 former so that it would be flush with the fuse side doublers. I left this area exposed for cooling and ease of battery access. I found it might have been easier to make a hatch using the removed sheeting and rare earth magnets for attachment.

Now I was at less than 8 hours of total build time. That included all radio installation, modifications for e-flight and re-shrinking covering. Very impressive.



Per the instructions, the battery was adjusted to achieve the 2 5/8” CG mark. Note the battery only had about ½” of front to back movement before it hit either the firewall or F3 former.

Rates and transmitter setup

Rates were set according to the manual. I normally use expo on elevator and ailerons as well as dual rates for insane aerobatics. The Herr Little Somthin Extra was not really a 3D ship so I did not set it up for extreme rates required of those aircraft.

Sig Now Provides Directions to Electrify the Lil Extra ARF!

Since the beginning of this review, Sig has also tested this great little plane with electric power, and is in the process of writing a single page instruction, including photos, which will be included in all future kits. The following information is directly from Sig:

Our Recommended Lil' Extra ARF electric conversion uses the following:

  • 1 each Maxx Products Himax HB2815-1400 Brushless Motor ("In-runner" type)
  • 1 each Maxx Products Clam Shell Motor Mount #ACC314
  • 1 each 25 amp Brusless ESC (we used the Phoenix 25 progamable unit)
  • 1 each APC 8 X 4E Thin Electric Propeller #LP0804E
  • 1 each LiPoly Battery Pack, 3S, 11.1v, 1500maH - 2100maH
  • 1 each Radio Shack DPDT On/Off Switch

The above components, easily installed per our instruction sheet, yielded a finished, ready to fly Lil' Extra ARF model that weighed exactly 27.9 oz. (Nice to be less than Mr. Llewellyn's listed weight of 29 plus ounces.) The flying characteristics are spectacular. We've flown this model in relatively high winds with no real problems. The model is capable of extreme aerobatics yet remains quite comfortable to fly. Flight times - using the Thunder Power 2100maH 3S pack - are in the neighborhood of 15 minutes. Take-offs are less than 10 feet on our grass field. Using full rudder deflection, the knife-edge characteristics are very good and more than acceptable. Of special interest is the fact that no additional access hatches were required to fit the batteries into the model - sometimes daunting for some people.


As is my normal procedure I snapped some pics of the plane before first flight. It is a great looking plane!

Time to head to the field!

Well, the weather finally cooperated. We had significant rain and thunder storms all through the night, but the wind had dropped to nothing on a clear May morning. It would not get better than this. I tossed the Herr Somethin Extra and my little Dystraction in the car. I needed the Dystraction as a warmup plane as I had not flown in almost two weeks.

I tossed the Dystraction in the air and at the three minute mark I heard a horrible sound. It sounded like the plane was flying apart (it was!), I cut the throttle and landed quickly. The propeller had broken in mid air! Was this a bad omen for things to come?!?

First flight

It was time, so I installed the battery, checked the control directions, dual rates and flap settings. I was alone, not a common practice for me with first flights. I usually fly with a friend to be there for urgent trim help and encouragement if needed.

The wind was blowing at about a 20 degree angle to the runway, so I lined up on the downwind side of the runway so I could drift over a bit. As it turned out that was not necessary. I advanced to full throttle and the model tracked straight and true down that side of the runway. I applied a touch of up and it lifted off smoothly. Yea!

I always have a set procedure flight for new airplanes. I climb to about two mistakes high and cut power a bit. Then I focus on initial trims. The Little Extra needed some minor trim adjustments, with two clicks of up trim and one click of left aileron. I then take my fingers off the sticks to confirm trim and that is my mental signal to relax and fly the airplane.

Once happy with the trims I check power pitch settings. Does it climb at full throttle and drop like a rock at motor off? The Extra did very well here with a very slight climb at full and it pitched down a bit at motor off. No significant trim changes from one to the other. This was just like I would have expected on this plane. It would likely have had less power pitch coupling but I moved the motor thrust line up about half an inch. That can cause issues on some planes, but no apparent ill effects here.

Next I checked rolls. With the controls set for the rates recommended in the manual I found roll authority much too slow for my liking. Plenty of roll control to fly, just not enough for me. I switched to high rates and that was just rolled about one per second. I like planes touchy in roll and not so much in pitch. The rolls were very axial and with the increased rates fast. Excellent.

Now on to pitch. Loops were nice and tight. The switch to dual rates was super tight. I liked the settings there, maybe just a touch more on low rates. I fixed that at home later. It had no tendency to snap out of the loop. Excellent.

Now to check the stall characteristics. I cut power and she did not bleed off speed! The Extra just continues right along, so long approaches will be necessary. Finally after what seemed an eternity of no power she was getting sluggish on the controls. No wing drops at all, just a gentle nose drop. It was clear I would have had good control authority down to the very low stall speed. Excellent.

Next I shot landings. I didn't plan on landing yet, I just liked to have this down for the inevitable. The Extra did take a while to bleed off speed, so a nice long approach was necessary. The first setup was so good I commited and landed! Perfect! Right on the center of the track errrrr I mean runway. OK not perfect, it was too fast, but it had great ground control. I brought the plane around and took off again.

Flight 2 – more aerobatics

Since we had no bad habits noted, I decided to try some more advanced aerobatics.

Inverted flight

Inverted required a bit of down stick, indicating the center of gravity was plenty far forward at the manual recommended CG. I decided to move the battery back about a half an inch. Hopefully that will eliminate some of the up trim (that becomes down when inverted!) and make inverted flight more neutral. I hate flying inverted and always have, so let's move on.

Split S turns

Just a thing of beauty. A touch of aileron for roll to inverted and cut throttle and pull the stick for the half loop. Perfect! I did a few more and it tracks like it is on rails. My favorite turn around maneuver.

Immelman turns

No issues here. Up elevator and a half roll on top. Great again!

Knife edge

Well most planes don't do everything well. Here was one area for improvement. I rolled ¼ and kicked in the rudder. It tucked and rolled. Bummer. I figured I was just flying too fast so I tried it again. Roll and apply rudder very slowly. Better, but it still rolled and tucked to the canopy side. I realized it would need lots of mixing to cure that. I must admit, I am used to KE on nice long sleek pattern ships. These ships give you more time to “play” and make small adjustments. I had as much rudder throw as I could, my norm, and I can say the rudder was very effective. I will practice more, I need it anyway!


I like to do first spins pretty high to make sure the plane has plenty of time to recover. So I get about three mistakes in altitude and slowly cut throttle and add elevator. Once the plane was climbing straight up and almost to a stop I kicked full left rudder, aileron and gave full up. It snapped instantly and did two full turns before running out of speed, dropped the nose 180 degrees and continued spinning. The nose stayed almost straight down. I liked this! Centering controls stopped the spin almost instantly. No opposite rudder needed. Nose stayed almost vertical and a touch of up and ¼ throttle had the plane straight and level in a flash. Excellent!

Snap Rolls

Two words: fast and wicked. They stopped instantly when controls were centered. No opposite correction needed. Wow! I am going to like this plane!

Hammerhead turn

Pulled up, slowly decreased throttle, when almost out of forward speed, kick the rudder and over she went. The rudder was very effective and it kicked the plane over with authority. The short tail moment helped with that. It was still smooth and pretty.

Outside loop

Just like inside it did it well and no roll out. Nice big ones too!


I did the third landing with flaps and had to hold too much up elevator. It was not pretty, so I decided to wait to get home and add elevator mixing. On the fourth flight I really worked on slowing it down for landing. It did so much better and I greased this landing in right down the centerline of the narrow track. This will be a keeper for sure.

Is This For a Beginner?

The Herr Little Somethin Extra is not a beginner airplane. This is due to the fact that it required constant control inputs to maintain controlled flight. I feel it would make a great 3rd plane and aerobatic trainer.

Flight Video



The airplane came with a complete hardware kit, and was nearly complete out of the box. It was very easy to assemble with a total build and e-conversion time of eight hours. The plane was built straight with surfaces and wing aligning properly. Construction appeared to be excellent with plenty of glue used. It was built tough and a touch on the heavy side. The covering had some wrinkles, but the color scheme was attractive and it was easy to see and keep oriented once airborne.

This plane did like the pitch speed of the 10x7 prop I am running. I like faster planes so that may just be me talking here. At 20 amps and 116 watt/lb performance was excellent, but it was not significantly overpowered. It felt perfect to me. Takeoffs used 10 feet of runway.

I was also very pleased with my power system choices. The MP Jet out runner was strong, quiet and powerful. It was also a huge value at $55, $68 with the shown firewall mount. The Cool ESC performed flawlessly. I find it was easy to program and like the fact that I set the cutoff voltage 2.6v-3v at .1v increments. A nice touch. My Tanic packs performed flawlessly. In my opinion Tanic packs are the ones to beat. They always give me an honest 10c and are not over rated on capacity. I like getting 2220 mAh into a pack rated at that capacity.

The plane was a great flier. It groved well for a short coupled plane and it had no bad habits. It was very much like its big brother. In fact, at times, I had a hard time remembering it was not the bigger ship! It looks great and is rugged. It would make a great addition to anyone’s hangar. Herr has a hit with the Little Somethin Extra. I highly recommend it.

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Jun 09, 2005, 01:56 PM
Registered User
pda4you's Avatar
Let me know if you guys have any questions. This bird has much more airtime now and I can say that it is an amazing flier. I am very happy with it!

Jun 10, 2005, 10:09 AM
Fly Every Day
pmmartin's Avatar

This a very nice review that you did. I am just completing a conversion of this plane and it should be flying in the next day or two. It is a twin of yours right down to the color. I am however using the MP Jet in-runner with the 4:1 gear box and initially a 10X6 prop. We will see how the performance compares to yours. It is amazing as I had done most of the same changes concerning battery access etc. I had it pretty much done before your review appeared.

We hope to see more reviews from you in the future.
Jun 10, 2005, 10:14 AM
Registered User
pda4you's Avatar
Great minds think alike!

Glad to know we were on the same track. What size MP Jet motor are you using?

Jun 13, 2005, 09:20 AM
Nice review. I also just finished electrifying the Little Extra (Turquoise & Cream) after seeing it at the Toledo show. I installed an Axi 2212-20 using an APC 9-6E prop and Kokam 1500 3S1P pack. All up weight was right at 26 oz ready to fly (at 1/2 throttle, I might add!). I simply cut the glow engine mount off at the first set of motor mount holes and installed a firewall at that point, keeping the fuselage the same length. I also cut a hatch in the bottom, but only as far back as the former. Great flyer! Everyone is impressed. I love it!
Cliff Tacie
Jun 13, 2005, 09:30 AM
Registered User
pda4you's Avatar
Thanks Cliff and welcome to the eZone!

I wondered about a lighter power system, glad to know that works well. You are 3oz less than my AUW.

It is a great airplane, I am also very happy with mine!

Jul 04, 2005, 08:37 PM
Registered User

Herr Engineering Little Extra

I really enjoyed the review. As it turns out, the review came out just a few days before I finished mine. So much for being original or the first...

Based on what I have read, it appears that I have the lowest powered version of the plane. I am using an AXI 2212/26 turning an APC-E 10x7 prop. As for a battery, I am using a Thunder Power 1320 3S1P pack. After the conversion, the ready to fly weight came in at 25.5 oz, including the 0.5 oz I had to add in order to balance the model properly. I later found out that the plane did not need the additional nose weight.

With this set up, the motor draws about 13 amps (static) giving the plane about 130 W of power to fly on. This is slightly more than the 12 amp maximum for the motor, but while in flight, the plane draws about 7.5 amps. The plane flies really well and it makes for a very nice sport plane; however, it could use a little more power. I have also tried different props (a 9x6, 9x7 9x7.5 and a 10x7) and have found that the 10x7 works best. It was interesting to note that all the props drew nearly the same current and power (watts) from the battery. I guess that the plane likes the additional static thrust from the larger prop (it gives it better acceleration).

All in all, it is a very nice plane and I would highly recommend it. The kit was very well built and the conversion was quite easy. The only suggestion that I would make is to use a power system that can deliver at least 150 Watts (such as an AXI 2212/20).

Jul 05, 2005, 08:52 PM
Registered User
pda4you's Avatar
Thanks Teo.....glad to know you have it working with a "lighter" power system....
Mar 20, 2008, 03:50 PM
Registered User
alan west's Avatar
Mar 28, 2008, 06:10 AM
Registered User
As much as I DO NOT like elctric stuff, I also have this exact model sitting on my shelf, and NORVELS are pretty much impossible to get most of the time. I suspect I am going to have to go electric to get my Little Something Extra in the air. I really like 4-strokes and had given some thought to a .30 Saito but I think even that is a bit large for it.

Mar 28, 2008, 09:08 AM
Registered User
pda4you's Avatar
The .30 Saito is far too large for this small ship - prop clearance would be an issue as well.

If you don't want to go electric the OS .10 would be perfect -

Mar 28, 2008, 10:14 AM
Registered User
alan west's Avatar

Wow, over three years watching this for thread to come to life. As if it was yesterday. Right where you left off.

Mar 28, 2008, 02:45 PM
Registered User
Whatever I do, I won't be using anything with bushings. If it doesn't have bearings, I won't use it. If I can build LEETLE tiny bearings into dental handpieces and they turn 300,000 RPMs, a small Glow motor from the factory can have them too. They cost maybe 4 or 5 bucks a pair.
I'm sure I'll find a decent motor for it once I get into that project. It's small, maybe it being a bushing motor won't bother too much. As long as it has a decent carb with proper adjustments. Air bleed carburetion is as bad and maybe even worse than bushings, in my book..

I'm sure there is something out there that can meet my specs the way I like it. The Little Something Extra is a really cool little plane. Now all I've got to do is replace the motor mount I carved out when I was going to go electric with it (before I decided I hate electrics). Hey, if this hobby was easy, everybody would be doing it. Hey, wait. Everybody IS doing it these days...hrmph.

Dec 28, 2008, 08:44 AM
Promoting Model Aviation...
Murocflyer's Avatar
Originally Posted by ARFY
Whatever I do, I won't be using anything with bushings. If it doesn't have bearings, I won't use it. If I can build LEETLE tiny bearings into dental handpieces and they turn 300,000 RPMs, a small Glow motor from the factory can have them too. They cost maybe 4 or 5 bucks a pair.
I'm sure I'll find a decent motor for it once I get into that project. It's small, maybe it being a bushing motor won't bother too much. As long as it has a decent carb with proper adjustments. Air bleed carburetion is as bad and maybe even worse than bushings, in my book..

I'm sure there is something out there that can meet my specs the way I like it. The Little Something Extra is a really cool little plane. Now all I've got to do is replace the motor mount I carved out when I was going to go electric with it (before I decided I hate electrics). Hey, if this hobby was easy, everybody would be doing it. Hey, wait. Everybody IS doing it these days...hrmph.

A thump on the chest to get this thread breathing again.


What motor did you go with?


Mar 25, 2009, 09:01 AM
big-john-52's Avatar
saw this plane for the first time yesterday and man what a sweet bird this will be my next build and fly. the guy at the hobby shop said he is getting a few more because of the interest in this little plane. all I need is money and a little lime mabe next


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