Ultrafly Extra 300 ARF Review

Pat Mattes explores this quick building aerobat with great looks and even better performance! Pat tests the Extra not only with the stock, included motor, but also with 2 brushless upgrades, and flies the extra with a Tanic LiPo 3-cell pack.

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Introduction

All decals installed.
All decals installed.
Wingspan:35"
Wing Area:263 sq. in.
Weight:22 oz (as flown)
Length:30"
Wing Loading:11.5 oz/sq. ft.
Servos:Futaba 3103
Transmitter:Futaba T4-NBL
Receiver:Futaba R114H
Battery:3-cell Tanic Pack LiPoly
Motor:Falcon 400 geared 3:1 (incl.)
Upgraded Brushless Motor:UltraFly A/30/24, A/30/29
ESC:Great Planes ElectriFly C-30
Manufacturer:UltraFly Model Corporation
Available Online From:Tower Hobbies

The Extra 300 hardly needs any introduction in the aerobatics world, with its instantly recognizable lines, short coupling, and aerodynamically balanced control surfaces. With clearances for large control deflections, UltraFly’s rendition of the Extra promises to deliver great aerobatics!

This review is the 4th article on UltraFly Model Corporation’s line-up of foam ARF models. The Extra 300 is their most recently released model, following in the same footsteps of previously released models with its quick assembly, interlocking parts alignment, and scale appearance. This model also boasts several product enhancements since the release of their first models which will be covered in more detail.

The lineup of previous articles on UltraFly Model Corporation and their products can be reviewed on The E Zone by clicking these links:

Kit Contents

As with all UltraFly Model products reviewed so far, the Extra 300 kit included injection-molded polystyrene foam major components, all required hardware, foam glue, decals, and a specifically engineered motor/gearbox combination. It also included two sheets of full color decals.

While reviewing the manual I noticed some definite improvements over the previous ones. There were still some translation problems, but there was no difficulty in understanding what was required in each step. Other improvements noted were better attention to order of assembly, a shaded aircraft pictorial on each page showing what section was being worked on, easy part identification for the plastic accessories for each step, and in general a cleaner, more concise appearance to each page.

Since the assembly techniques were so similar among the products reviewed so far, this review will take a higher-level approach than the previous reviews. The photographs and supporting text will cover multiple steps at a time and will not go into fine detail.

Additional Equipment provided for this Review

The following items were provided for the Hawk, PC-9, and the Extra 300 reviews. Thanks to R/C Toys Inc. for the Tanic Packs, and to Futaba USA/Great Planes for their support!

Assembly

Foam Part Preparation

The foam parts were lightly sanded to remove the mold-vent bumps and allow the decals to be installed easier. There was very little preparation required beyond that. The control surface parts needed to be cut away from the parent parts, and only small amounts of foam needed removed during that procedure. This allowed for quick removal and minimal post-separation cleanup. The elevator and rudder servo mounting locations were molded into the aft fuselage, externally, close to the tail surfaces for reduction of any potential control slop.

Fuselage and Tail

Wing

Servo Installation and Decal application

The instructions called for the servos to be installed prior to the decals, however I felt it would be easier to align and apply the decals without trying to work around the rudder and elevator servos. These decals were completely different than with previous UltraFly models. During the first two reviews I experienced problems with the decals with color de-lamination and decal fragility. The new decal material is very strong and did not exhibit de-lamination even during repositioning.

Pre-Flight Preparation

The Extra balanced a little aft of the recommended CG range, so I added an ounce of nose weight to compensate for the lighter Lithium Polymer Tanic Pack. The balance point was set to be at 70mm from the leading edge of the wing (NOT the very front of the wing). The instructions specify the range to be between 70 and 75 mm from the leading edge. I set the balance point at 70 mm for the first flights.

Since the Extra 300 was primarily geared towards performance and aerobatics, I opted to use the 3-cell Tanic right off the bat, rather than load it with Nicad packs. The Falcon 400 motor system was equipped with their “Firestone” gearbox, with a 3:1 ratio. The provided propeller was an APC 9x6 Electric, and with this setup the current draw was 16 amps on a fresh charge.

A transmitter range check was performed, and a check of all servos assured proper travel direction. Control throws could have been set lower or higher than the settings I used, but for the initial flights I chose smaller amounts (the instructions recommended +/- 25 to 35 degrees for ailerons, +/- 25 to 35 degrees for elevator, and +/- 35 to 45 degrees for rudder).

Control throws as measured for the first flights were as follows:

  • Ailerons +/-10 degrees
  • Elevator +/- 13 degrees
  • Rudder +/- 13 degrees

As always, pictures of the completed plane were taken PRIOR to the first flight....

First Flights

I secured the Tanic Pack in the fuselage since I knew I would be doing aerobatics. I also put a small piece of household tape at the rear of the canopy just to ensure the magnet joint wouldn’t separate during hard maneuvers.

The Extra 300 has landing gear, but my flying field was covered in 6 inches of snow and a hand-launch was required. I found it easier to hold the model behind the wing, rather than in front. With a little up-trim in the elevator, I advanced to full throttle and tossed the Extra forward. It immediately climbed out, and I backed off power and set the trims to normal. I spent a minute familiarizing myself with its flight characteristics, then decided to start doing some basic maneuvers. I went back to full throttle and pulled a very easy loop, followed by a tighter one. Tracking was just fine, so I rolled it upside down and did an outside loop. The outside loop was slightly larger than the inside loops, but again tracking was just fine and the Extra had no problem performing it. I went with several rolls and found the Extra did well in fast or slow rates. If I hit full aileron and compensate only with elevator, the rolls are nice but just slightly out of true axial. For a smooth roll I found it necessary to kick in just a bit of rudder when the plane was up on each wing tip. I flew the Extra inverted for a while, finding only a small amount of elevator correction was required to maintain altitude. While the battery was still fresh I pulled the Extra skyward and experimented with its vertical performance. It would head straight up fine for a short while, but I could tell the 400 motor wasn’t going to hover it. During vertical maneuvers I had plenty of elevator to manage pitch direction, but quickly ran out of rudder authority. I had intentionally kept the control throws at the lower rates, so that didn’t surprise me.

I continued flying for several minutes, curious as to the Extra’s speed range. At full throttle it moved along at a nice, scale pace, and tracked solidly. An aerobatic plane typically doesn’t slow down well, but this one slowed just fine. I let it stall, but recovery was easy without much altitude loss. After about 7 minutes of full throttle flight, the battery was just showing signs of weakening. Since my fingers had long since frozen, I brought the Extra around for a landing approach, kept the nose high for a slow landing, and set it softly on the snow. From launch, through flight and landing, the Extra 300 was as easy as flying the oldest, most comfortable plane in my fleet.

Since it was a sunny day, although still very cold, I went out for a second flight with some of the nose weight removed. I had a total of 1.3 ounces of lead taped onto the cowling, and I lowered this to about 0.8 ounces. This moved the CG back to the 75mm position. I launched again with a full charge on the 3-cell Tanic Pack, and just like the first time, the launch was right out of my hand. I went through some of the same basic flight and aerobatic regimens as the first flight, but I did not like flying it with a CG this far aft. It was too jumpy for my tastes, although it was very agile and responded immediately to input.

The second flight was short on purpose, as the temperature had gotten colder. I kept this flight the same configuration as the first, including the aft CG location. I called it a day and went back to into the shop.

Just to verify the recommended CG range, I performed a graphical calculation of the mean aerodynamic chord (MAC). The graphic is included in this review. From the MAC determination, I found that UltraFly’s recommendation of a CG location 70-75mm from the leading edge puts the balance point at approximately 39 to 45 percent MAC.

Using the analysis, I determined I had flown the Extra at the 39% position for the first flight, which is considered a good starting position for an aerobatic plane. The second flight was flown with the CG at the 45% position. This would be a good position for practicing hovering, but makes “standard” flight more difficult. For my own tastes, I decided to continue flying at the 39% position for future flights.

For the next flight, I decided to increase the control throws. The elevator and rudder were set to the limit the servo could provide using the provided arms. The aileron connectors were screwed further down on the torque rod, to the point where I had to remove a small amount of foam.

These settings yielded the following throws:

  • Aileron +/- 16 degrees
  • Elevator +/- 23 degrees
  • Rudder +/- 16 degrees

During the third flight of the Extra, I could tell the difference in the settings right away. The rolls were faster and the loops a little tighter. Most noticeable was the increased rudder throw, which helped noticeably during my attempts to go vertical.

UltraFly Brushless Motor Upgrade

The UltraFly brushless motors, the A/30/24 and A/30/29, had proven to be incredible replacements for the Falcon 400 motor in the Hawk and the PC-9 reviews. I switched out the C-30 brushed controller with one of brushless controllers, and installed the A/30/24 into the Firestone gearbox. Using the same APC propeller and 3-cell Tanic, the A/30/24 took the current to 13.5 amps. Even though the current was lower than the Falcon 400 motor, the performance increase was evident the second I launched the Extra. As soon as I had launched, I pulled vertical. The Extra remained in that condition, climbing slowly but surely. The extra rudder throw helped keep it going in a straight line. I went through several of the same maneuvers as before, and the combination of greater throw amounts and higher power of the brushless motor made those same maneuvers much more enjoyable. I brought the Extra down lower and attempted to hover. I had to back the power off slightly to prevent climb, and the Extra felt like it could hover at this power level. The only limitation was myself, as I simply wasn’t good enough at this type of flying to keep the tail under the nose. Lastly, I tried knife-edge flight. Again, the increased rudder throw helped. I performed knife-edge for about a hundred feet, but it started to lose altitude. The 16 degree throw each way simply wasn’t enough, and I needed to find a way to increase this. Flying time was just over 8 minutes, with most of the flight at full power. I probably had more time available on the battery but didn’t push it that far.

The next flight of the day, the 4th overall so far, was made with the A/30/29 installed. Current draw with this setup was 19 amps, within the limits of the battery and just slightly outside the recommended range for the A/30/29. I tossed the Extra using only about half-throttle, and it still took off with authority. As soon as it was out a few feet, I pushed full throttle and pointed the Extra skyward. It went vertical and stayed that way, climbing straight up until I was satisfied it wasn’t going to slow down. It was a fairly decent climb rate. After bringing it back to lower altitude, I put it through the familiar paces. The power was pretty phenomenal; with only half throttle it booked along well. I made some vain attempts at hovering, and had to back the throttle off to keep from going straight up. I managed to keep the nose in a decent position, enough to be satisfied that with more practice I could hover this little aerobat. Even though I hadn’t changed the relatively small amount of rudder deflection, with the added power and speed of the hotter brushless motor, I had no problems getting the Extra to knife-edge and stay that way the entire length of my field and more. This proved to be a rather potent setup for this model! Although the current draw was significantly higher, I was surprised to get the same 8 or so minutes worth of flying time. I hadn’t flown at full throttle for the entire flight, as the Extra was rather spirited with this setup. The frequent use of varied throttle settings allowed me to use the power when needed, and still provide plenty of power at even half throttle.

Going to Extremes

My higher control throw settings provided the Extra with plenty of authority for aerobatics, but were still short of the minimum settings specified. I wanted to try the throws the manufacturer recommended, but my stock servo arms were limiting the travel. Long arm servo horns are not available for the 3103 servo, so I used the clamp-on style servo arms provided in the kit. These worked quite well and prevented me from having to fabricate extensions.

With these settings, flying the Extra was just wild. With the high power, light weight, and this much control throw, I performed some incredible maneuvers. Some of them I’m not sure were even intentional! There was plenty of rudder authority to compensate for nearly anything, and enough elevator power to stall the wing on demand. The Extra 300 did some pretty impressive flips. I experimented with flat spins, lomcevaks, and just plain throwing the sticks in all directions, and it was a very exhilarating flight.

Flight Video/Photo Gallery

Editor's Note:Our author has not been able to get video of the Extra at this time, but we were anxious to get the word out on this great flying aerobat! We hope to add video footage to this article at a later date. Assuming we do, we will place the video here, make note in the article's description on the E Zone home page, and move this article back to the top of the listing. We will also add a post to this article's discussion thread, so subscribing to that discussion will make sure you get to see the added material!

Conclusions:

As pointed out in the other UltraFly reviews, the alignment features in the designs helped ensure all surfaces were straight and true. The provided foam glue worked great for all areas of assembly, and had a reasonable cure time. There were numerous improvements made to the manual which improved assembly and readability. Mostly notable however were the improvements in the decals. They were high quality, had deep color, applied well, were very durable and turned a white-foam model into a very colorful one in a very short time. And of course having performed this review with my flying field covered in snow, a little color on a white plane helped flying out quite a bit.

One item for improvement would be a better fit of the canopy base to the fuselage, since it was slightly wider than the assembled fuselage. A second item I might address in the future is changing the offset aileron linkage to an inline one to correct some aileron differential I noted. These were very minor in the grand scheme of things, and certainly didn’t do anything to detract from the very favorable assembly and performance of the Extra.

The Futaba radio equipment and Great Planes speed controller performed well. The availability of longer factory servo output arm options is limited for this particular servo but the output arms provided by UltraFly worked fine. The 3-cell lithium polymer Tanic Pack provided a light, high-power battery source that delivered consistent power throughout the entire flight.

The Extra 300 performed very well as an aerobatic plane, executing every maneuver I knew how to do, and certainly capable of several other stunts I haven’t learned yet. It was light, nimble and responsive. In addition to the stunt capability, it still behaved well at lower speeds and landed easily. As with the other models reviewed previously, the performance of the provided Falcon 400 motor and gearbox made for a very nice-flying, well-matched power system that provided plenty of enjoyable flying. With the stock motor the Extra will loop, roll, snap roll, fly upside down, and many other aerobatic maneuvers. With the brushless upgrades, the aerobatic capabilities are even greater. It was truly a joy to fly.

Thread Tools
Jan 02, 2005, 06:41 AM
Registered User
Aio_1's Avatar
From the picture in the review the Falcon 400 motor appears to be a pretty standard speed 400 type motor but with a plastic back plate rather than the more usual steel one. Is this correct?
I ask because in the review you mention that current draw with your setup was 16A on freshly charged cells. That seems awfully high for a speed 400 motor especially when operating at ~11V.

Aidan
Jan 03, 2005, 09:00 AM
6 months to finish a rtf
pulsery2k1's Avatar

ultrafly 400 motors


Some one from our club has one of these and flew it with the same
setup ,(400)which worked great for 5 flights on the 6 flight the plane
started smoking ,when out of control and crashed , it was found
the speed control had melted and the motor had completely
burned the brush's .These motor's can't take more then 10 amps
at 11.1 volt for very long.
Jan 03, 2005, 12:57 PM
Registered User
Aio_1's Avatar
pulsery2k1,

Which motor are you refering to? There were 3 motors tried in the review. The Falcon 400 and 2 different Ultrafly motors: A/30/24 & A/30/29. I don't think there is such thing as an Ultrafly 400 unless you mean the one listed as 'Falcon'?

Aidan
Jan 03, 2005, 05:46 PM
6 months to finish a rtf
pulsery2k1's Avatar

stock motor


i

Sorry it wasn't my plane I was referring to the stock motor which camewith
the plane. he (the owner of plane) didn't use a watt meter, very Important
and if the motor was ment for only 8.4 - 9.6 volts using 11,1 volts didn't
give it very long life. I learn this a few years ago when a 400 powered
sea plane wouldn't lift off the water I went to 12 v plane few better by
I went thru a few 400 till I found a PnS 12 volt 440 that gives great
power . check my models at pulsery2k1
Jan 03, 2005, 06:13 PM
Registered User
Aio_1's Avatar
The speed 400 motors work really well on 11.1V providing you reduce the load so that the current doesn't increase. You can even afford to decrease the current and still have a significant power increase. If you're using a gearbox 3s Lipo makes great sense with standard speed 400s (6V and 7.2V) and shouldn't wear them out any faster than on a lower voltage.
The standard Speed 300 motors on the other hand have a very high kV and the brushes do seem to wear out quicker at the higher RPM associated with 3s operation.

As for your post earlier:
Quote:
...These motor's can't take more then 10 amps
at 11.1 volt for very long.
If it's a speed 400 type motor then I agree, in fact I'd say even 10A is on the high side for a standard 7.2V motor. The 6V version might be okay but would last longer at 8 or 9A. I think the Falcon motor is a low kV motor for use at higher voltages which should mean it has an even lower current handling capacity.

Aidan
Jan 04, 2005, 08:14 AM
RC Player
Hi Folks,

The Falcon 400 motor compare to Speed 400 7.2V or 6V is a lower KV motor. Our KV is about 20% lower then the speed 400 7.2V. We found higher KV would contribute to better efficiency so we make this motor to work on at least 9.6V Ni-Hh. It may be used for 12V Ni-Mh or 3S Lipo but you have to watch out on the amp. This motor will burn down easily if the amp draw is over 12amp. And you should give it a very good cooling condition which means no hovering & no heli. If the amp draw is over 12amp, try to increase the gear ratio to one level higher. The recent Lipo technology is progressing fast. The 3S Lipo we have would be drawing exactly 12 amp. It is possible that a new formula Lipo may have lower resistance and exceed 12amp then cause the motor to burn down. Please test it first. By using a higher 3.89:1 gear ratio, you can still use the 3S Lipo to operate this motor properly without burning it down!

Sincerely yours,

Charlie
Jan 04, 2005, 08:38 AM
Registered User
Aio_1's Avatar
Charlie,

Thanks for the information.
Could you tell us how the KV is decreased? Are there more windings with thinner wire or are the magnets stronger? What sort of efficiency do the 12A setups you recommend have?
I would not have expected that 12A could be used while maintaining efficiency and motor life if the wire resistance is higher due to increased windings.
It seems to me that the motor case itself is the main limiting factor on heat dissipation and so the max total power losses for both this and standard motor would be the same. Above that the motor would become too hot and burn the wire enamel, soften the endplate or demagnetise the magnets.

For example

Standard Speed 400 6V:
8V * 11A = 88W
say 55% eff
Loss = 39.6W

Falcon 400:
11V * 12A = 132W
For the same loss:
(132-39.6)/132 = 70% efficiency

I'd be VERY surprised if the motor can manage 70% efficiency at this current!!!!

Aidan
Jan 04, 2005, 08:54 AM
RC Player
Hi Aidan,

The motor does has better/higher magnet then the Speed 400 series. The winding is also thinner and more wind than the speed 400. In our own test if using the same power input, we can generate 5% more rpm than speed 400. Our efficiancy is round 58-61% depends on the amp draw. The best efficiency comes on 8-10amp not 12amp.
But 12amp does give you the best power output than most 400 motors. It is usually 10.8V x 12amp=129.6watt input. Our KV is about 2200-2300. Remember to limit the amp below 12A with proper cooling then you will be fine with this motor!

Charlie
Jan 04, 2005, 09:48 AM
6 months to finish a rtf
pulsery2k1's Avatar

Speed 400 motors


Hi

As I mentioned before I had problems with stock speed
400's . I found a 12 volt 440 (same size at speed 400)
that put out higher rpms and by using a 4 to 1 gearbox
am able to get 21 oz trust at only 8 amps using a 9X6
apc prop .the 190 (seen in my posted pictures under
Pulsery2k1) has more than 90 flights and still going
strong. by drawing less amps the entire system last
alot longer. heat is no problem and even after a 8-10
flight the motor and pack is only warm (using 1050 11.1
lipo pack) the plane at 19 oz flys great at 1/2 throttle
and is areobatic at 3/4 and will go vertical at full power.
pulsery2k1
Jan 04, 2005, 11:31 AM
Registered User
Aio_1's Avatar
pulsery2k1,

Have a look at this thread about using standard 'can' brushed motors with 3s Lipos. It's a very good thread. Lots of practical data and discussion on the topic.Can motors on 3s Lipo

Charlie,

At the power input you're suggesting and the efficiencies you are quoting the losses will be approx:
129.6*0.42 = 54.4W
This seems like a lot of energy for a speed 400 size motor to dissipate.
I suspect throttle management would be essential to keep the motor running long term. This sort of power can also be used for higher KV standard motors under the same constraints (ie very good cooling and/or throttle management). The only difference is that the RPM would be higher and different gear ratios would be used. I don't think the efficiency of ~60% is any better and may be worse than can be achieved with a standard motor. I'm not trying to find fault with your motor - just confused as to it's advantages. If the pricing is similar to the other speed 400s then it's good to have a different KV motor available. How's the efficiency on 4s Lipo at say 8A if you've tried it?

Aidan

Aidan
Jan 04, 2005, 10:36 PM
Registered User

Ultrafly Extra 300 ARF Review


I thought I better chime in here! You guys write so fast, it's hard to keep up.

Due to the questions presented here, I re-checked currents with the stock Falcon 400 motor. I did NOT have a fresh charge on the 3-cell LiPo, but it was probably close to full. The current draw was 15 amps. As I stated in the review, with a FRESH charge on the LiPo I got 16 amps initially. So I stand behind what was originally posted in the review.

Now, here's where some discussion points:
1 - These are STATIC readings, the plane is not moving during measurement. You don't have that level of current draw when the plane is flying, it can drop by 10-20% during flight, depending on how much prop pitch you have.

2 - Even static readings are not necessarily so static. Both the voltage and current will continually drop as time goes by, even with the best NiMh or LiPo's. Stating an initial amp draw can be misleading, but readers wouldn't want to see volt/amp stats listed every 10 seconds. And at full throttle, every 10 seconds you will see different readings.

3 - You no longer have 11.1 volts under that kind of load. Depending on the state of your battery, and the type, etc., it could drop by a volt or more. This also drops the current level. Again, the current constantly declines as time goes by. (Testing at full throttle at my bench)

After 30 seconds of running, the current was around 13.5 to 14 amps. In flight this WILL be less, unless you can keep it in a perfect hover which will in essence be the same as static ground test. I'm willing to bet the in-flight current at full throttle was in the 11-12 amp range. The Falcon 400 performed just fine. Now, here's something else... Since the motor and speed controller have been wired up ever since the Hawk review, I've continued to use the same motor ever since. It's been through many flights with different packs on the Hawk, many flights with different packs on the PC-9, and now many flights on the Extra. It continues to be a very strong motor!

Pat
Jan 05, 2005, 02:16 AM
RC Player
Hi Folks,

I would have to explain a little more about this unique Falcon 400 motor!
As a manufacturer, we test the motor on a static bench and the top limit of this motor is at about 12amp & 120watt for maximum power input. For some formal document we even narrow this down 11.0amp. We know this motor may survive in even higher amp draw and more power input, however, we have to be conservitive to the numbers. Because people will challenge us if he burn down down the motor within our number limit. Extra, PC-9 and Hawk are all flying in a faster speed if compare to many park flyer models. The fast airflow did provide a much better cooling condition. But if you put that motor on our Cessna and using APC 10x4.7 prop, it will burn down the motor. The amp draw is about 14-15 but the flying speed is about 12-20km/h. It is relatively a slow flying model. Thus, there isn't enough cooling air to wash out the heat. It would burn down easily! We did burn down one motor once! So all of your comments are correct! 3S lipo may burn down a 400 size motor. 3S Lipo also may make many 400 size airplane rock for as many as 40-50 flights. The important thing is the amp draw, maximum watt input and cooling condition. Just watch out for that and try it. You should enjoy the out come.

Thank you for your tolerance and valuable oppinion !

Charlie
Jan 05, 2005, 11:24 AM
Registered User
Aio_1's Avatar
Pat and Charlie,

Thanks for your responses!

From what you say the motor sounds like it does survive above the power input I would have expected. It sounds like a useful motor.

I'm aware of the different variables involved such as the pack voltage/ reduced load in flight/ cooling due to airspeed etc... I used 11.1V because considering that a fresh pack is 12.6V unloaded, it is common for the voltage under load to be close to the nominal for a significant period (maybe 30s depending on the pack size and resistance)at the start of a motor run. I have not tested any speed 400 motors to destruction myself but I didn't think the case could dissipate >50W. I would have expected excessive heat beyond about 45W even with good cooling. As you say the losses can be much smaller in flight due to reduced load. I was assuming that 16A was an initial static test current and that mean flight current would be much lower. My comments on my perceptions of other motors' limitations was based on the same comparison.

I'll go away and stop being such a sceptic now!

Aidan
Last edited by Aio_1; Jan 05, 2005 at 11:28 AM.
Jan 05, 2005, 08:40 PM
Registered User
I am curious hear more of your thoughts on heat dissipation through the case. Theoretically you can build up enough heat to cause the magnets to lose their power (I forget the term), but I think its difficult to get to that temperature unless the motor is actually encased in foam. The only failures I have ever had with 400's or similar sized motors in 10 years of electric flying experience is brush/commutator failures (well, and a few bushings worn out too....).

I know that Graupner, with their Terry and Mini-Piper actually encase the motor in foam but the provided air path is through the case slot, across the commutator and brush, and out the other case slot! Their thought pattern seems to be to keep those elements cool and disregard the case temps. Another way to keep the commutator/brush temps down is to properly break them in. I've used the underwater method to great success. With the commutator and brush better matched, there is more surface area to conduct the current through and thereby less localized heat buildup in these components. Just more food for thought!

Pat


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