DLuders

I'll ATTEMPT to explain. On his webpage, Philo wrote that "These [synthesis] charts [below] summarize the above curves. The most meaningful shows the various motors sorted by maximum power they are able to deliver at 9V. Because rpm/torque curve is linear, a motor provides maximum power when load slows it down to half of no-load speed." Looking at the graphs above, the no-load speed for the Power Functions XL Motor (at 9V) is ~225 rpm, so half of that is ~113 rpm. The no-load speed for the 5292 RC Buggy Motor (at 9V) is ~925 rpm, so half of that is ~413 rpm. Looking back to the topmost charts on this post, one can see that the PF XL motor's torque is ~22.5 N.cm at ~113 rpm, and the 5292 RC Buggy Motor's torque is ~8.8 N.cm at ~413 rpm: This definition of a "Watt" is: "One watt is the rate at which work is done when an object's velocity is held constant at one meter per second against constant opposing force of one Newton." In other words, 1 Watt = 1 Newton*meter/second. For the PF XL-motor: (~22.5 N.cm) x (113 rev/min) = (0.225 N.m) x (113 rev/min) x (1 min/60 sec) = 0.42 Watt. For the 5292 RC Buggy Motor: (~8.8 N.cm) x (413 rev/min) = (0.088 N.m) x (413 rev/min) x (1 min/60 sec) = 0.60 Watt. Philo's chart "shows the various motors sorted by maximum power they are able to deliver at 9V....a motor provides maximum power when load slows it down to half of no-load speed." @ Philo: Can you help explain why my calculations don't match your chart above? Philo continues by saying "The following chart sorts motors by torque and by no-load rotation speed (of course this depends a lot on internal down-gearing of the motors!!!). Torque chart lists torque at half speed point." [The "Maximum Power" point mentioned by Philo above]

You really cannot go wrong with any of these excellent Lego Technic sets. Recommend reading the set reviews on http://www.Brickset.com ; just type in the set number in the top-right box and see what others say about them.

@ Kisvakond: Nice mods! Could you rank-order the relative importance of your five modifications to the 9398 set? I viewed your High-Definition video in its entirety, and came up with this order: #1 Importance to 9398's Rock-Crawling Ability: "- Third party tires for better crawling performance" #2: " - Wheel hub gear ratio changed to 8/24 for more torque" #3: " - Modded front & rear axle for higher ground clearance" #4: " - 8878 LiPo battery box for lower center of gravity" #5: " - Added extra nose weight for better climbing perfomance" Do you agree?

On his "LEGO® Power Functions Servomotor" webpage, Philo (Philippe Hurbain) measured the response of the SM to the Power Functions Receiver's signals. He wrote that "Spikes of current at 8.5N.cm load reaches 600mA." On this Powerfunctions.Lego.com webpage, The Lego Group wrote that "The Servo Motor delivers a maximum torque of 250 mNm (300mA). Without load it rotates with 360 degrees per second. This corresponds to the output turning from center to horizontal position in 0,25 seconds. "The current consumption will depend heavily on the load it is driving. Under normal conditions it can be around 150 mA and it should never exceed 300 mA." - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - On his "LEGO® 9V Technic Motors compared characteristics" webpage, Philo wrote that the PF L-Motor rotated at 390 rpm at no load. At 9V, the current was 0.49 Amp and its "stalled current" was 1.3 Amps. On this Powerfunctions.Lego.com webpage, The Lego Group wrote "It delivers a maximum torque of 45,4 mNm (430mA). Without load its rotation speed is around 384 rotations per minute [VERY CLOSE to what Philo had measured]. "The current consumption will depend heavily on the load it is driving. Under normal conditions it can be around 225 mA and it should never exceed 430 mA." - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Philo wrote that the PF XL-motor rotated at 220 rpm at no load. At 9V, the torque was 14.5 Newton-cm and the current was 0.55 Amp. Its "stalled current" was 1.8 Amps. The Lego Group wrote that it "delivers a maximum torque of 90,4 mNm (406mA). Without load its rotation speed is around 224 rotations per minute." [Very close to Philo's measurements] "The current consumption will depend heavily on the load it is driving. Under normal conditions it can be around 300 mA and it should never exceed 406 mA." This is a bit lower than what Philo measured.

On that Powerfunctions.Lego.com website that legolijntje and Zblj found, it says that "SM (Servo Motor) -- The Servo Motor will not be available through LEGO.com until March 2013" and "LM (Large Motor) -- The Large Motor will not be available through LEGO.com until March 2013." If you have not bought the 9398 4x4 Crawler set yet, it may be the only way to obtain these new PF motors for 7 months! There is no mention about the new "Version 2" 8884 Power Functions Receiver in the PF Products lineup -- I guess the existing supply must be bought-out before The Lego Group offers them for sale....

You can see from the replies above that it is not true that you got "NO" reaction. 'Bye.

What a nice Technic MOC! It's great that you could fit 484 pieces in such a small vehicle. You can drive it outside in bright sunlight without having to worry about the sun's infrared light interference with a Power Functions Receiver. The custom stickers are a nice touch.

@ Thelonious Monk: People DID reply to your original MOC, and liked it. It is inspiring. Heck, I doubt I would have thought of it. Please don't stop posting your creations.

Are the antennas screwed in all the way on the two units?

@ Saberwing40k: There are some nice Lego Rover Wheel designs on this BrickVista website.

Whoa, that's one LONG Top-Fuel Dragster! I always wanted to build a Lego Technic dragster, but I never could get it right. There's got to be a fine balance between Speed, Torque, and Weight in such a MOC. If you could get some of those new Power Functions L-Motors connected to the "Version 2" Power Functions Receiver (that come with the Lego 9398 4x4 Crawler set), maybe you could get almost the same speed (and a lot more torque) by using fewer motors (and fewer battery boxes). This will decrease the weight and allow the dragster to accelerate faster. From Philo's Lego 9V Technic Motors Compared Characteristics webpage, you can see the relative properties of the PF M-motor and new PF L-motor:

Lego Technic Ambassador Jetro de Chateau told me about the newly-available Hispabrick Magazine 014. He said, "HispaBrick Magazine 014 is out and once again there are tons of goodies for the Technic fan. I'm sure it'll appear on the frontpage soon, but I wanted to give you the heads up: http://www.hispabrickmagazine.com/en ." I downloaded the 104-page 34.5-MB PDF file (available in English and Spanish), and found these interesting articles related to this forum: (Page Number and Topic) 20 GBC with character 50 Mechanical Technic parts and how to use them 52 Tutorial: Pneumatic Sequencing (II) 58 An introduction to Robotics with LEGO® MINDSTORMS (XI) 87 Review 9398: 4x4 Crawler [by Jetro!] 91 Model: 1980 Citroën 2CV Charleston Thanks, Jetro, for all of your work to enhance the hobby!

I believe you are talking about JunkstyleGio's 9395 Hinged Loading Platform. His PDF Building Instructions were posted on the (now defunct) MegaUpload, but I saved a copy of it on my hard drive. Send me an e-mail at LudersDG@MSN.com and I'll e-mail the 564-kB file to you.

Maybe he will next make a Lego Technic version of James May's Lego House!

The Lego-compatible Rotacaster Wheels really make this wheelchair very nimble!

@ vliet: I tried 3 different 1.9" offroad scale tires on the Power Pullers 22969 wheel, but the rubber could not stretch past the inner rims to be able to mount both sides of the tire equally. So, the next regular size up in commercial RC tires is 2.2".

I like the orange truck's aerodynamic cowling that forces air SMOOTHLY around the towed trailer. The slanted windscreen is also more aerodynamic. I like how the Power Functions Receiver is hidden in the orange truck too.

There are answers to many of your Lego Power Functions questions on the official Powerfunctions.Lego.com FAQ webpage. "How many Power Functions Motors can I drive from one Power Functions Battery Box?" "As a rule of thumb, you can drive 2 Power Functions XL-Motors, 3 Power Functions Train Motors or 4 Power Functions M-Motors at the same time from one Power Functions Battery Box. If you wish to run a combination of motors, you can e.g. have 1 XL and 2 M running together. The XL-Motor requires about twice as much power as the M-Motor. The Battery Boxes and the IR Receiver have overload protection, so attempting to drive too many motors will not damage anything. The power a motor consumes depends on what function the motor is performing. Motors will operate best when driving a small load."

@ Gen1US: Welcome to Eurobricks! This is a nice small model that would look great in a Lego City scape -- do you plan on building it with real bricks? The front badge looks like a Renault....

Their advantage is "minimal space" taken up on the narrow, congested roads in Europe. I lived in Berlin, Germany for 3 years and know that all of the American vehicles there looked ABSOLUTELY RIDICULOUS and out-of-place, due to their large size. American semi trucks (operating in the wide-open spaces) have a "longnose" design to allow for easier access to the engine compartment, and to allow for better "crumple zone" crash protection in the event of a front-end collision.

@ AVCampos: We've all got it!

Conchas wrote in his video that the sand was clogging up the 9398's Portal Axle gears -- that's why the travelling speed was slow. In addition, he uses Rechargeable AA batteries which only produce 7.2 Volts total (instead of 9V total with Alkaline batteries).

Yeah -- I didn't drive my 9398 into the water like Conchas did with his!

My son and I just made . See the Lego Technic 9398 alternate B-Model in action against the A-Model. We tested:1) The difference in performance between using 1.5V alkaline batteries and 1.2V rechargeable batteries, 2) The susceptibilty of the stock B-Model to rollover crashes, compared to the A-model's lower center-of-gravity, 3) The effect of swapping Lego tires to help resist rollovers. We tested the stock Lego 54120 balloon tires against the Lego Unimog's 92912 tire and the Lego "Power Puller" 32298 Tire. No permanent damage was done to the two models shown in the rollover carnage!

@ vliet: I believe that the RC4WD Hollowpoint Scale Comp 2.2 Tires would fit onto the Lego Power Puller 22969 "Wheels 62mm D. x 46mm Technic Racing Large". Their specifications (Outer Diameter: 5.28" (134mm), Width: 1.92" (48.75mm), Inner Diameter: 2.2" (56mm)) should work without the need for CA Adhesive (Superglue).