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Author Topic: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)  (Read 226 times)
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Konrad
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« on: September 11, 2017, 04:50:26 PM »

Let me admit that I have this addiction. I as a modeler am ashamed to admit that I’m addicted to foam ARFs. True modeling to me is where one creates a representation of a subject or a simplified testing tool.
What I have here is a no bones example of check book modeling. For $260 (Labor Day sale)I found this Taft Super Scorpion 90mm 8 cell sport jet for the same price as the 80mm 6 cell Freewing.
http://www.bananahobby.com/6-ch-taft-hobby-red-super-scorpion-90mm-rc-edf-jet-arf.html
https://www.motionrc.com/collections/jets-and-ducted-fan/products/freewing-super-scorpion-80mm-edf-jet-pnp

This is exactly the type of model I like to get. That is one that has a bad reputation on the forums. For about 3 hours of hobby work and $50 to $100 dollars in replacement parts (if any fail my burn in) I’ll have a model that will out perform the $450 FMS 6 cell Super Scorpion. Here is a photo of the Super Scorpion next to the Dynam Meteor. I will say that transportation might be an issue!
https://www.horizonhobby.com/product/storefronts/plug-n-play/fms-brand/super-scorpion-90mm-pnp-p-fmm099p

Yes, this will become a detailed review of the Taft Super Scorpion. On first blush it looks to be a good value for the current asking price of $299. Everything worked straight out of the box. My JDPower's initial customer quality evaluation is that the Taft Super Scorpion is not up to par with the FMS offerings. Initial quality appears to be much better than what I've experienced with Dynam models. I'd place the quality right around what we might expect from say Freewing. That is good but in need of some work prior to first flight. To be brutally honest the quality we find in the  Taft Super Scorpion really is just half a step below the Freewing models. On balance the Taft Super Scorpion a great value for real modelers who have the skills and fortitude to put a little work into their models.

We shall see if at the end of this exercise I can hold my head up as a real modeler.

All the best,
Konrad
Attached files Thumbnail(s):
Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
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Konrad
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« Reply #1 on: September 13, 2017, 12:29:14 PM »

Keeping with my trust but verify approach to these mass market toy EPO models. I’ve inspected the power system. For the most part I’m pleasantly surprised at what I found. I was really happy to see that Taft added a cap pack to the battery side of the ESC to combat the issue of damaged MOSFETs as a result of the long battery leads. ALL OEMs should ad these if the anticipated battery leads are to be longer than 6” to 8” long! I was also surprised to find dual switch ESC’s included in the power system. Very nice touch.

I was a little disappointed in that I found a mis-marked motor. The sales brochure and the kit manual clearly state that the motor is a 1300KV motor. Unfortunately the motor in labeled as a 1500KV motor. Modeling the fan on 8 cells would indicate that the motor is close to a 1300KV motor the current draw measured of 66 amps closely matched that of a 1300KV motor.

What little I could find about the X-team motor is that this 3674-1300KV has a current limit of 48 amps yet has a power limit of 2.4KW. This isn’t as bad as one would first think. The motor really is designed for “buggy” use. Being as this is in an EDF it is in the cooling blast of the efflux which allows for huge over amping. As measured I’m getting 66 amps but at a voltage of 32V the power output is well below the 2.4KW limit as it is only 2.1KW. That being said the 309g mass of the motor really is a bit on the light side. One really needs to add a finned heat sink to the motor.

I was a bit shocked to find that I could not remove the EDF unit from the airframe without taking it apart. One needs to remove the inlet lip to draw the EDF unit through the hole provided by Taft to service the EDF unit. This cause some issues at the point of manufacture as glue was dripped onto the rotor blades when trying to glue on the inlet ring. This might account for some of the rough running I noticed in my testing.  I’ll try to balance the rotor to see if this smooths things out.

Edit: Current limit is 48 amps per X-Team.
Attached files Thumbnail(s):
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
« Last Edit: September 13, 2017, 02:16:08 PM by Konrad » Logged

Cut it twice and it's still too short!
Konrad
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« Reply #2 on: September 14, 2017, 06:18:06 PM »

Plugging away at the Taft Super Scorpion I’ve found some Good Bad and Ugly points.

What I really like is the look of the anhedral stab. This combined with the splayed out vertical fins make this a great looking model yes even better than the MD F-18 E/F US fighter! On a more practical note I hope it addresses an issue I’ve notice with the other offering of the Scorpion. Having flown the Freewing 80mm Scorpion and the 70mm ROC/FMS Scorpion I notice that the elevator response was a bit lethargic with the straight stabilizers. I suspected that this might be due to some separation bubble on the stab or wake turbulence from the wing. With the anhedral stab Taft is insuring that some part of the stab is working in clean air regardless of the plane’s attitude.
I have to admit that seeing this stab anhedral gave me concern about the attachment points to the fuselage. Clearly Taft is NOT using a through spar (rod) to mount the stab and its associated pivots. Taft has give the stab a nice wide bearing area inside some large plastic load spreaders. What I do have are some grave concerns about the length  of the stub to which the stab is bolted.

I did notice a no fly item and that is the stab push rods. Taft (and most other toy EPO vendors) is using a low grade 1.2 mm wire with stamped thread. This wire is so flexible that Taft added a carbon tube to try to stiffen it from flexing mid span.  This weak wire and the poor quality spherical end combined with the gross course 0.75 mm thread pitch necessitated a full rework of the push rod. I’m using Dubro 2mm Swivel Ball Links Cat# 368. I’ve threaded a 2 x 0.4 pitch thread onto a 0.078” (nominal 2mm) music wire. You might have noticed this means that you will end up with the rod that allows for twice as fine a length adjustment! The wire is 110mm long with 2@ 14mm long threads. (To thread music wire you need to anneal the wire otherwise you are likely to break you 2mm die).

I do have a concern with the stab elevator servos. Not with the brand or quality of the servo. If Quique Somenzini is willing to put the reputation of his new venture “Flex Innovation” on the line with Potenza, I’m sure he has vetted them well. My issue is with the size/power a 19 gram 2.9 Kg-cm sounds rather weak for this weight and speed of aircraft. With proper geometry it might work. But I read far too many folks are crippling the servo’s performance by limiting the motion of the servo to 50% or less. You should alway try to set up your servo/surface throw so that you are using 100% to 120% of the servo’s normal rotational throw. This keeps the power torque up and improves the surface resolution. MOVE THE PUSH ROD CLOSER TO THE SERVO CENTER LINE!

The battery area appears to be huge, at least 87mm wide and 56mm tall. This space goes all the way 30mm past the wing’s carbon through spar! I can’t understand why so many folks claim to have issue making the CofG with the appropriate batteries.

The ESC mount, well that is just a bad idea!

All the best,
Konrad
Attached files Thumbnail(s):
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
« Last Edit: September 14, 2017, 07:21:43 PM by Konrad » Logged

Cut it twice and it's still too short!
Konrad
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« Reply #3 on: September 14, 2017, 06:20:07 PM »

Flight is all about fluid flow.

Over all I’m NOT impressed with the flow ducting on ether end with this large model. The upthrust really has me concerned. I recall having a horrible time with changes in flight trim with changes in power setting with the Multiplex twister (it had down thrust in the thrust tube). I fear that Taft is using upthrust to over come some concerns about being nose heavy. Upthrust is the wrong trim variable to adjust for being nose heavy!

All the best,
Konrad
Attached files Thumbnail(s):
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
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Cut it twice and it's still too short!
Konrad
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« Reply #4 on: September 15, 2017, 01:43:41 PM »

Some corrections are needed.
While Taft does provide 2 SBEC they are not redundant. One is a set for 5.5V. I assume this is to power the radio and servos. The other is set at 7.45V with a 2 pin JST connector on the output. I assume this is to drive some other accessories, such as brakes (No brakes are provided on the wheels).

I was in error saying that the FreeWing 80mm Super Scorpion was a flat tail ship. She does have a slight anhedral stab. This is much like this Taft Super Scorpion but at what appears to a lesser angle. (I'd like to make note that the stab pin purchase area appears on the Freewing 80mm Super Scorpion to be twice as large as the area on this Taft 90mm Super Scorpion.)
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Konrad
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« Reply #5 on: September 15, 2017, 11:11:38 PM »

Cleaned off the glue from the Taft rotor and rebalanced the rotor. Wouldn’t you know it, the glue (weight) was almost 180° away from where I needed to add weight to get a smooth running EDF unit.

I performed my 5 minute burn in on the Potenza DS19 servos and they past with no issues. But looking at the size of the stabilators I wasn’t comfortable driving them with a 2.6 Kg-cm servo. As I had a few HS5085 laying around I felt these were more suitable. Luck would have it that removing the plastic pocket, Taft uses as a screw pad to mount the servo, leaves a foam pocket that fits the HS5085 perfectly. Keeping with my belt and suspenders approach to flight safety I glued in the HS5085 with both Welders contact cement and hot glue. The bond area is close to the same as with plastic pocket. The only down side with this is that it will take some effort to replace the servo should the need arise.

I will reuse these Potenza DS19 servos to replace the 13 gram aileron servos.

Something to be aware of is that regardless of the level of modeling good mechanical protocols need to be adhered to. In the case of these metal servos there needs to be some form of lock washer added. Without the lock washer (star washer) the servo arm screw WILL vibrate out, with the result being total loss of control from that servo.
Attached files Thumbnail(s):
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
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Konrad
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« Reply #6 on: September 18, 2017, 06:45:05 PM »

More correction/clarification!
This is the price of doing these builds live.

The power from the stock EDF unit just jumped from a current draw off 66 amps to that of 107 amps with a steady draw of 98 after 30 seconds.
I can only attribute this to better batteries; 25C for the 66amp reading and on the bench, 55C (TP Lightning series) for 107amp and with the EDF in the fuselage.
Will definitely be adding that finned heat sink!!! And limiting the flights to 3 an hour to keep the duty cycle (heat build up) in check.

Well, Taft isn’t making it easy for me to up grade this ship. I wanted to move the Potenza DS19 from their location as stabilator servos aileron servos. While the aileron servo cover/mount will hide the larger Potenza DS19 the aileron pocket and liner Taft provides to hold the cover/mount will not allow an easy upgrade.

P.S.
It has to be more that the battery impedance! I was messing around with the ESC programing this weekend. Maybe I released some hidden monster in the ESC programing. Re-running the numbers in the predictive programs it is looking like the motor may in fact be a 1550Kv motor (I owe X-Team an apology the motor may not be mis-marked). If it is indeed a 1500Kv to 1600Kv motor the nominal amp limit rose from 48 amps for the 1300Kv to 70 amps the motor 1500Kv labeled)

PPS
Not sure I trust any of these EDF simulators. I should just remove the fan and measure the Kv directly. Unfortunately I can't safely remove the fan as there is no motor hold feature on the Taft adaptor and the nut appears to be held on with a very strong thread locker.
Attached files Thumbnail(s):
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
« Last Edit: September 18, 2017, 08:19:03 PM by Konrad » Logged

Cut it twice and it's still too short!
Konrad
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« Reply #7 on: September 19, 2017, 01:27:54 PM »

Well, just incurred my first of what I’m sure will be the first of many added expenses, spare parts.

This has nothing to do with Taft or any quality issues. I just like to have replacement parts on hand for all the models I have in flying condition. And the things that first hit the ground, spinner and landing gear, are high replacement items for me. So I got some retracts.

Again luck would have it that Horizon Hobbies (HH)is closing out their inventory of Taft parts. While HH carried the Viper jet but not the Super Scorpion.
Many of the components are the same between the Viper and the Super Scorpion.
https://www.horizonhobby.com/SearchDisplay?searchTerm=taft&categoryId=&storeId=10151&catalogId=10051&langId=-1&pageSize=40&beginIndex=0&sType=SimpleSearch&resultCatEntryType=2&searchTermScope=2&showResultsPage=true&searchSource=Q&pageView=
« Last Edit: September 19, 2017, 01:53:29 PM by Konrad » Logged

Cut it twice and it's still too short!
Konrad
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« Reply #8 on: September 20, 2017, 02:30:03 PM »

Just got back from the machine shop where I fitted a 28mm long (actually the fins are 24mm) finned heat sink to the motor.  I’m using “Arctic Silver Thermal Adhesive” both as the heat transfer compound and as the adhesive to attach the heat sink. I took the opportunity to machine a 4mm long pilot diameter into the finned heat sink. Lacking any other data I machined this pilot diameter to have a wall thickness of 1mm. In hindsight it might have been better to make the wall 0.5mm or 0.7mm thick. The purpose of the pilot diameter is to give added support to the rear of the stators and to add some rear support to the long motor.

I find it odd that most heat sinks are supplied with an anodized finish. This is odd for a heat sink as aluminum oxide (the anodize without dye)is an insulator! I did grit bast the ID of the heat sink to get improved thermal transfer from the motor case to the heat sink. I’m ashamed to say that I kept the blue anodize as it looks good against the red fuselage of the Super Scorpion.
Attached files Thumbnail(s):
Re: Taft Super Scorpion 90mm 8 cell, Sport Jet (Banana Hobby, Thanks Alex)
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Cut it twice and it's still too short!
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