Greg Covey

Although the weather was nice this weekend, the winds were too strong to test fly the third scale Cub from World Models. I decided to test everything in my backyard and check the CG. The CG was a bit nose heavy which will be fine for the initial flight. I measured 87.5 amps on one of the paralleled packs which means my current flow is 175 amps near full throttle. This provides 175amps * 14 cells * 3.4v per cell =8300 watts or 11h.p. which is 2300 watts over my target 6000 watts. I can either reduce my prop size or cell count to approach my goal. Either way, the XTRM 7050/06 from [link=http://www.hangitrc.com/motors.htm]Hang-It R/C[/link] has tremendous power!

My friend, Paul Weigand, made a spinner hub similar to the TruTurn [link=http://www.truturn.com/cgi-bin/store/agora.cgi?p_id=tth1500bcu&ppinc=pro]TTH-1500-B-CUB[/link]. It really gives the nose an added scale look.

We made a short video showing the power test and some taxi turns in my backyard.
[link=http://www.gregcovey.com/reviews/CubTesting.wmv]Cub Testing Video[/link] (2meg)

Greg Covey

While waiting for good weather to test fly the Cub, I discovered that Dubro makes [link=http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=dubro+cub+wheel&search=Go]Cub Wheels[/link] in 1/5, 1/4, and 1/3 scale sizes. The 1/3 size wheel mounts right on the 1/4" diameter gear rod.

Instead of using the supplied yellow Cub Hub Caps that came with the Dubro wheels, I cut the hubs from the World Models kit down to size for a better color match with my red and white clipped wing Cub.

Greg Covey

Our "Chamber of Commerce" day finally arrived on the first weekend in November. A plane this size requires a team to help assemble as well as document the results through photos and video. My pilot for the test flight was Ron McGrath, the father of Team JR's Devin McGrath. Ron has several decades of flying experience.

We had to drop the cell count down to 12s in order to obtain a reasonable power output level. I measured 156 amps which provided a full throttle power level of 6700 watts. This was much more power than needed and everything was well within specification.

The Dubro Cub wheels looked great and all the control surfaces were checked out. We range checked the Spectrum receiver using the convenient button on the back of the transmitter while walking several hundred feet away.

I discussed the flight plan with Ron and we were ready to go...

photos by "Papa Jeff" Ring

Greg Covey

The Cub took off with only 1/3 throttle and the tail lifted without any elevator offset. No trimming was needed so we flew it around for a while to test the maneuverability.

photos by "Papa Jeff" Ring

Greg Covey

The Cub had much more power than needed so most of the 12 minute flight was under 1/3 throttle. It could loop and roll without issue. Our rolls (in the video) used rudder compensation but did not have any differential set up. The 10AH 12s battery pack was only 50% discharged upon landing.

photos by "Papa Jeff" Ring

Greg Covey

The Cub landed gently with or without power. In the maiden flight video, we landed after a few minutes to adjust the throttle trim. This allowed the prop to stay spinning as it eliminated the dead zone and gave the pilot finer control. Although we had no issues with the Cub performance, something bad happened and we were forced to land after 12 minutes. The big 1/3 scale Cub was safe on the ground.

[link=http://www.gregcovey.com/reviews/WMthirdCub.wmv]Clipped Wing Cub Maiden Flight Video[/link] (18meg)

photos by "Papa Jeff" Ring

Greg Covey

As Ron and I walked back to the pit area, we discussed what happened to the motor that caused the flight to end. It turns out that several magnets had broken free, causing the motor to completely seize up. Fortunately, the Cub wingloading was so light that it didn't require any motor power to land. It was safe on the ground.

I reported the issue to Hang-It RC and they immediately took the 7050 off their Web site. I felt this was a very responsible move on their part and they conveyed that they were very concerned about the motor issue, yet happy that no damage occurred to my Cub.

They have since reported that after speaking with the manufacturer, the 7050 is already undergoing changes to assure this doesn't happen in the future. The motor will now have a new casing (housing) to better support the magnets at each end. They are also looking into filling the gaps between the magnets with resin for additional support.

I will post updates to anything I hear from Hang-It RC and hope to get the Cub back in the air next Spring.

Since I discovered that 3000-4000 watts is plenty of power to fly aerobatic maneuvers with the third scale Cub, here is another suggestion for a usable setup:[ul][*] AXI [link=http://www.hobby-lobby.com/brushless-axi5345.htm]5345/16[/link] motor[*] Jeti 99-amp [link=http://www.hobby-lobby.com/jetispin.htm]SPIN[/link] ESC or[*] Castle Creations [link=http://www.horizonhobby.com/Products/Default.aspx?ProdID=CSEPHX110HV]HV-110[/link] ESC[*] 12s 5AH-10AH LiPo pack[*] APC 24x12 [link=http://www.hobby-lobby.com/elecprop.htm]e-prop[/link]
[/ul]

Greg Covey

The first of the new redesigned [link=http://www.hangitrc-estore.com/XTRM-7050066000-watts-NEW-CASING-DESIGN_p_3-101.html#]XTRM7050-06[/link] 6000 watt motors arrived from Hang-It RC. It was displayed at the SEFF 2008 event and then shipped to me for testing.

The casing has been redesigned to hold the magnets more securely in place. There are also several very impressive bearings on each end of the motor.

The XTRM 7050-06 is a 176 KV Brushless Outrunner with a current capacity of 150 amps @ 60 seconds. A maximum efficiency of 90%, a no load current @ 10vdc of 2.8 amps and an internal resistance of 15 Mohms. This outrunner is designed to run on 40 NiCad/NiMH cells or 12-15 LiPo cells. Dimensions are 82x90mm and weighs 3lbs. 7oz.

Greg Covey

Since a prop adapter was not yet available for the XTRM7050, and, I did not want to screw the prop directly to the motor, I needed to create one. My friend, Paul Weigand, a retired machinist from Kodak, came up with a solution to allow me to use my existing APC props and hub with a 12mm center hole. This elegant adapter design used a section of 12mm threaded steel rod which gets screwed into the hub first and then into the mounted aluminum adapter. The length of the rod ensures that it gets recessed into the motor hole but does not touch the bearing. The metric screws were supplied with the motor.

Greg Covey

The prototype [link=http://www.hangitrc-estore.com/X70-Radial-Mount_p_11-65.html]X70 Radial Mount[/link] had several issues. The six screws supplied with the mount did not fit as the heads would hit. We decided that 3 screws were sufficient to properly hold the motor to the mount. Since the large 12mm mounting holes were too far apart for my steel box, I decided to make my own adapter from 1/4" thick aluminum stock. Extra weight wasn't an issue on this big third scale Cub.

I had screws and bolts that I used to mount the 1/4" aluminum block and 3/4" hardwood spacer to the steel 4x4 post cap. I wasn't certain of the size but it fit perfectly into a 3/8" hole.

Greg Covey

I tested the motor in my backyard like before. First, it was tested without a prop and then with both my 26" and 24" APC e-props for balance and vibration. Since I don't have an easy way to make a 12s 10AH Lipo supply, I will likely test fly it using the 24" APC prop on my 14s 10AH Lipo supply.

The photo shows the 26" prop mounted with the 12mm hub.

Greg Covey

We tested the Cub using a 14s 10AH LiPo supply and a APC 24" prop. Although the Cub flew just fine, the motor did not perform to expectations and we decided to land before trying any aerobatic maneuvers. Upon inspection of the motor, we found issues with the magnets breaking and the aft end becoming unscrewed against the aluminum mount. I cannot recommend this motor for others to use.

Since I plan to perform aerobatics with the clipped wing Cub this summer, I will now use my recommended AXI 5345 setup from the [link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=952]review[/link] and keep you posted.

[link=http://www.gregcovey.com/reviews/WMthirdCub2.wmv]Clipped Wing Cub Flight Video with XTRM7050[/link] (7meg)

photos by "Papa Jeff" Ring

Greg Covey

My AXI [link=http://www.hobby-lobby.com/brushless-axi5345.htm]5345/16[/link] motor arrived in three days. It comes with two 12mm prop adapters that allow you to mount the motor either behind or in front of the firewall.

I prepared the motor by soldering on the mating connectors for my Jeti [link=http://www.hobby-lobby.com/jetispin.htm]SPIN200[/link] ESC and then installed the additional collar on the drive shaft which provides extra security when using the radial mount position in front of the firewall.

In order to obtain the proper distance from the firewall to the prop, I decided to use the [link=http://www.espritmodel.com/index.asp?PageAction=VIEWCATS&Category=729]AXI 53xx[/link] HD Universal Aluminum Mount from Esprit Model.

Greg Covey

After first marking my center lines, the HD Universal Mount was secured to the Cub firewall using 1" long, #10-32 hex head screws and T-nuts. I used the 3.5" extension rods. The mount is a bit pricey when compared to my original inexpensive 4x4 post caps but it is a quality machined mount that is very easy to install.

Greg Covey

The motor was secured to the front plate using four M4 x 20mm screws.

My plan is to use the APC 24x12 e-prop on a 14s 10AH LiPo supply. This should provide about 4500 watts which will be plenty of power to perform aerobatics with the third scale Cub.

Greg Covey

The AXI 5345 power system proved to be a winner. After making some changes to the prop size and cell count, I was fortunate to have it test flown by Team Futaba's Dan Landis. It didn't take Dan long to get comfortable with the Cub as he performed aerobatics, slips, slow flying around the field, and a few tricks like hammer heads and one wheel touch-n-gos.

Here is my final setup that delivers strong aerobatics and vertical climbs. The throttle can be set to full without cutouts.[ul][*] 13s 10AH LiPo[*] 22x10 APC e-prop[*] Timing reduced from 5 degrees to 0 degrees on the Jeti SPIN ESC.
[/ul]
photos by Richard Landis

Greg Covey

The third scale Cub got a chance to perform for a crowd at the Hamburg, NY event this weekend, just South of Buffalo. The strong vertical climbs and knife-edge passes across the field were mixed in with plenty of beautiful scale flying by NATS competitor, Scott Miller. After a 10 minute flight, the 10AH batteries were still half charged.

hanko

where can you buy one of htese