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Aug 31, 2007, 07:26 AM
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Build Log

Flite 40 ARF Low wing Eco plane/pwr sys w/video


Flite 40 ARF Low wing
From Dymond Modelsport Ltd. ( www.rc-dymond.com )
3904 Convoy St. #110
San Diego, CA 92111
A review, build and modificatioins by:
Ken Myers

Copied from Web page July 25, 2007.
“Closeout
List price: $119.00 (this was posted as a strike through)
Price: $50.00
You save: $69.00 (58%)
Flite 40 ARF Low wing Aerobatic Trainer. 60" wingspan Laser design wood and fiberglass construction. Fiberglass turtle deck. Can be assembled as tail dragger or tricycle landing gear Airplane. Excellent flying characteristics with Gunther 45/3 and 3S Li-Po battery. Needs 60 A ESC”

(photo 1 - box)

I received the plane on July 24 and took a photo of the parts in the box. The box the ARF (almost ready to fly) plane was packed in had no markings identifying the manufacturer. There were no markings or graphics of any kind on the box. The kit/ARF contained no written materials. There were no instructions, written or pictorial, no parts sheet, nothing. There was no way to identify what part of the world this ARF came from. My best guess would be southeast Asia or China.
On the morning of July 25, I removed the parts from the plastic wrap, inspected and weighed them.
The wood seems to be typical southeast Asian wood. That is, it is hard as a rock and heavy. The covering material seems to be some kind of heat shrink of fairly decent quality. The only covering that needed some ironing were the blue star graphics, which were lifting a bit from the white covering used for striping.
10/06/07 WARNING! after several flights, the horizontal white stripe on the left wing panel lifted from the leading front red stripe creating a gap that could not be seen when the plane was just sitting. This caused air to flow into the wing (not a good thing), create a "buzzing noise" and make the handling difficult. Iron down all covering joints on the wing and add some striping tape as "insurance". (see notes on how crazy this buzzing problem was in posts below)
The wood parts for the kit appeared to be laser cut and the actual design of the framework, tail feathers and wing were quite good.
The airfoil is flat-bottomed with a bit of a resemblance to a Clark Y.

Wing Specs:
Left wing panel
Chord: 11 13/32 in. (0.40625 in.)
Span: 26.5 in.
Weight: 287.4g + 19.75g (tip, noted below) = 307.15g
Area: 302.26563 + 21.3 (tip, noted below)= 323.56563 sq.in.

Right wing panel
Chord: 11 12/32 in. (3/8 in)
Span: 26.5 in.
Weight: 287.65g + 22.25g = 309.9g
Area: 301.4375 +21.3 = 322.7375 sq.in.

Left plastic wing tip
Widest point: 2.75 in.
Weight: 19.75g
Area: 21.3 sq.in when 3/16” is used as a gluing overlap

Right plastic wing tip
Widest point: 2.75 in.
Weight: 22.25g
Area: 21.3 sq.in when 3/16” is used as a gluing overlap
Wood wing Joiner/dihedral brace
Length: 10 3/4”
Weight: 22.4g

2 each wing bolts and plastic washers, 6.55g

Fuselage:
Main fuselage assembly from box
Length total: 43.25”
Note that the length from the tail end of the fuselage to the firewall is 43” as 1/4 in. of the sides extends for cowl attachment screws
Outside width from rear of wing saddle to firewall: 3 7/16”
Length from firewall to rear of wing saddle 17 13/32”
Weight: 285.75g

Fiberglass top deck, painted red:
Length: 36.5”
Weight: 105.6g

Fiberglass cowl, painted red
Length: 4 13/16:
Weight: 40.6g

Landing Gear:
2 Wire landing gear “legs” ~4mm dia., Weight: 55.4g
2 light foam wheels, 2 5/8” dia., 18.3g
2 wheel collets w/screws: 5.6g
2 plastic landing gear straps: 1g
4 strap screws: 2.2g
Total LG: 82.5g

Fuselage total: 514.45g or 18.15 oz.

Tail Feathers:
Horizontal Stab & elevator:
Span: 24.5”
Stab & elevator Weight: 91g

Vertical stab & Rudder:
Rudder Height: 9”
rudder weight: 21g
Vstab height: 6 5/8”
Vstab weight: 22.7g

Tail Feathers total: 134.7g or 4.75 oz.

While the written description on the Dymond site noted the landing gear could be set up as a trike or conventional gear system, no provision for a tail wheel was provided, so there is no weight listed here.

Out of the box weight: 1295.2g or 45.69 oz.
Note: My tail wheel assembly including 3/32 wire, tail wheel bracket, 1” wheel, 3/32 wheel collar, and 3 screws weight: 11.9g or 0.42 oz.

In the September 2007 Ampeer I discussed selecting a plane for a 5-cell M1 pack. At over 46 oz. with a tail wheel, the completed airframe weight is too heavy for good performance on 5 M1 cells. In that discussion, I noted that I prefer to use these cells at about 100 watts in per cell.
Since the completed airframe weight for this model is above that recommended a 5-cell pack, I looked at six cells, or 600 watts in.
For 600 watts in, the motor weight is typically between 600 / 3 = 200g and 600 / 1.5 = 400g. When doing a glow conversion, it is best to use a heavier motor, as getting the airframe to balance can be problematic if too light of a motor is used. In the September Ampeer, I noted that the mount, mounting hardware, prop adapter and prop can add up to 30% more weight, therefore the complete and mounted motor would be between 260g and 520g. The middle ground would be 390g or 13.75 oz.
A 6-cell M1 pack with Velcro, lead wires, connectors and balance plug weighs about 481g or 17 oz.
I noted that the all-inclusive radio weight is about 12.5% of the maximum target weight. If 100 watts per pound is used, which was my recommendation from last month, then the maximum target weight would be 6 pounds or 96 ounces. 12.5% of 96 ounces is 12 ounces or 340.2g.
The maximum target weight for this model is 2506.2g or 88.4 ounces or 5.5 pounds.

Step 1: Fuselage
Before starting work on the fuselage, use a pair of needle nose pliers to remove the landing gear blocks, noting which one is which. They should come out quite easily. Reinstall the landing gear blocks with epoxy and while you are at it, epoxy the joint between the landing gear plate and fuselage side.

(photo 2 - parts not used)

While the weight and quality of the fiberglass fuselage top was good, I didn’t really care for its shape.

(photo 3 - front of fuselage as delivered)

(photo 4 - fuselage front modified)

First, I removed the front part of the fuselage sides that extended past the firewall, removed the rounded top on the firewall and former F2, removed the cross members in the top of the fuselage in the tank area and the partial former that created the tank saddle using a sanding drum in a Dremel and some sandpaper. I protected the fuselage sides while sanding off the front protrusions by covering the covering with masking tape. I used transparent tape to “hold” the seam where the front of the covering and the firewall meet.
Step 2:
I constructed a turtledeck using the formers that were already there and sanding about 3/32” inch from them. A 3/32” balsa former was created and used at the rear of the turtle deck as well as the front. The formers were covered with 3/32” sheet balsa strips and sanded to shape. Masking tape was put along the top edge of the finished fuselage sides holding newspaper so that sanding the turtle deck would not mar the covering.
Step 3:
I knew that I was going to use the TowerPro/BP Hobbies 3520-7 motor that was on my test stand because it can handle the 600 watts of input power. It is a 265g motor. As discussed earlier, it is a little on the light side for this application and it did present balancing problems that will be discussed later.
The motor is mounted on standoffs using 8-32 machine screws and blind nuts (called “T” nuts in home improvement centers), which were purchased from Lowe’s, home improvement center. The complete motor system weighs:
4 8-32 "T" nuts 6.5g
4 8-32 2.25" screws 20.8g (these were 3” screws cut to length)
8 1" standoffs 12.7g
Motor, mount, prop adapter, prop washer, prop nut 295.7g
APC 12x7 sport prop 44.3g
Motor Total: 380g or 13.4 oz.
Note: The motor with power leads weighs 261.2g. Connectors, prop, prop adapter, mount and mounting hardware add 118.8g or 4.2 oz. The weight increase for all the mounting hardware and motor “accessories” was an additional 31%.

(photo 5 - hatch)

Step 4:
Using somewhat the same method as when building the turtledeck, I created the hatch from the front of the turtledeck to the firewall. The hatch is similar in design to that used on the ElectroFlying Fusion and is held in place with a couple of rubber bands from the inside.
Step 5:
Since the original cowl would no longer work with my hatch design, I built a new cowl of balsa wood. The cowl was built in place using the hatch as a guide. The cowl consists of a framework of 3/32”x1/4” balsa with a couple of 3/32” formers on the top of the frame and the whole thing covered with 3/32” sheet balsa and sanded to shape.
Step 6:
The completed turtledeck, hatch area and cowl were covered with white EconoKote and a Williams Brothers 1/6-scale sportsman pilot affixed in the cockpit with a windscreen trimmed with blue striping tape glued in front of him.

(photo 6 - battery installation)

Note: My DeWalt 9360 battery arrived from an ebay seller. I weighed the cells once they had been removed from the plastic case. The ten cells, once harvested, weighed 740g or 74g each. I made up a six-cell pack with balancing taps. The completed pack weighs 460.6g or 16.25 oz. Because of the way this pack was installed in the plane, no Velcro or pull straps were used on the pack. When I received the DeWalt 10-cell pack, all of the cells had a measured resting voltage between 3.29v and 3.31v with the majority of the ten cells reading 3.30v.

Step 7: Wings
I didn’t care for the provided plastic wing tips. New wing tips were cut, shaped and sanded from 1/2” sheet balsa. The tips were glued onto the wing panels; masking tape and newspaper were used to protect the covering while the tips were sanded to final shape. The tips were then covered with white EconoKote and a blue striping tape was used along the line between the new white tips and the red and white wing covering.

(photo 7 - hinges)

Step 8:
I don’t like hinges, particularly CA hinges! I prefer “MonoKote” hinges. If you are unfamiliar with this type of hinge, my review of the SR Batteries X-250 illustrates how to do them. http://members.aol.com/kmyersefo/x250.htm
Since this was a pre-covered ARF, there was a problem using this method. I had to be able to “hide” the hinge material. I stripped the red material from the ailerons, corrected the depth of the torque rod slots, applied the “Monokote” style hinges using white Econokote and ironed them to the wing. A white strip of Econocote covered the hinges attached to the red wing covering and was then “separated” from the red using blue striping tape. Later, the same procedure was used on the elevator halves and horizontal stabilizer.
The completed wing panels weighed; right panel 302.85g and 303.5g and each measured 27” long, giving a wingspan of 54”.

(photo 8 - root rib)

Step 9:
The wing panels were joined with 30-minute epoxy using the provided wing spar of unknown wood. The “hard” wood root ribs were drilled with several small holes to give the epoxy somewhere to go, since I thought that it would not “penetrate” this type of wood very well. The total weight of the wing, including the epoxy glue and wing bolts and washers was 645g or 22.75 oz. For those who like to keep track, the epoxy added about 10g or 0.35 oz. to the final wing weight. Later, another 16.9g were added to the right wing tip for side-to-side balance. (See step 18) That brought the wing total weight to 661.9g or 23.35g.
Step 10: The Tail Feathers
The elevator halves were prepared in the same manner as the ailerons. The wings were bolted to the fuselage and the alignment of the horizontal stabilizer adjusted. The stab was aligned with the wing with some fuselage material needing to be removed from the right side stab slot to align with the wing. The covering was removed from the stab slot and horizontal stabilizer. The horizontal stab was epoxied to the fuselage and the elevator halves “Monokote” hinged on and dressed up with white Econokote and blue striping tape. The finished and glued on horizontal stab and elevator halves weighed 92.5g or 3.26 oz.
Step 11:
A tail wheel assembly was created using a tail wheel bracket, 3/32” piano wire, a 1” wheel, 3/32” wheel collar and three small screws. The piano wire was 30-minute epoxied to the rudder in the appropriate position. The tail wheel assembly weighed 11.9g or 0.42 oz.
Step 12:
With careful alignment, the vertical fin was 30-minute epoxied into the slot in the top of the fuselage after the covering had been removed from the bottom of the vertical fin. The rudder was “Monokote” hinged to the vertical fin and fuselage and finished like the wing and horizontal stab. The tail wheel bracket was epoxied and screwed to the fuselage after the covering was removed from the area where the tail wheel bracket would attach. The finished weight of the vertical fin, rudder, tail wheel assembly and epoxy was 58.85g or 2 oz.
Step 13: Landing Gear
The landing gear legs, wheels, wheel collars, straps and screws were added.
Note: The airframe was now completed and weighed 1254.55g or 44.25 oz.
Step 14: Onboard Radio Installation, Installing the aileron servo
To install the Hitec HS-225BB servo in the wing, a 1/8”x1/4”x1 1/4” plywood rail was glued into the preexisting slot to shorten the slot. The supplied push rods, Kwik links and aileron connectors were used. The servo uses the “+” arm. The total weight of all of the parts was 37.3g or 1.32 ounces added to the 645g of the completed wing brought the total to 682.8g or 24 oz. When I weighed the wing on my digital scale I got 705g or 24.89 oz., so that’s what I’ll call it.

(photo 9 - fuselage servos installed and trial balance)

Step 15:
The preexisting plywood plate was used to mount the Hitec HS-225BB servos for the rudder and elevator. Two 1/8”x1/4”x3” plywood strips were used to shorten the preexisting holes in the servo mounting plate. Two 1/8”x1/4”x1” plywood strips were used to raise the rudder servo (actually lower it, since the fuselage is upside down during the servo installation). The total of the servos and associated hardware and wood pieces was 64.7g or 2.28oz. The elevator push rod with dual rods at the end, 2 Kwik links, 2 large nylon Great Planes control horns, 4 screws and two pushrod exits weighed 33.25g or 1.17 oz. The rudder pushrod, Kwik link, Great Planes control horn, pushrod exit and fuel tube safety keeper was 24.6g or 0.87 oz.
Step 16:
Since there were no instructions, I figured the Center of Gravity to be somewhere between 25% and 35% of the wing chord, which is typical for this type of plane. This is a constant chord wing, so it wasn’t that hard to do. With a chord of 11 3/8” (11.375”), 25% would be 2.84” and 35% would be 3.98”. I used masking tape on the wing saddle to indicate the guessed at CG placement.

(photo 10 - on balancer)

I set the plane upside down with wing attached on my CG balancer. The battery was set on the fuselage just behind the firewall. The CG was still aft of 3.98”. The Welgard 65-amp ESC was placed on top of the battery and the CG was still not quite at 3.98”. By now, I was wishing I had used a heavier motor! Finally, the 700mAh NiMH receiver pack was placed on top of the M1 battery pack and ESC. The balance just passed the 3.98” mark.

The quandary was to figure out how to actually get all of that equipment into the fuselage that far forward.

(photo 11 - battery tray parts)

(photo 12 - battery tray)

A battery tray was made of 1/8”x3 5/16”x3 3/4” plywood. Battery tray supports were made from 1/2”x1” balsa to fit in the tank compartment so that the ESC and M1 pack are bunked over each other with the ESC on the bottom. A battery stop was made with 1/2”x13/16”x1 1/8” hard balsa and a 4-40 screw, washer and blind nut.
The battery tray unit weighs 40.8g or 1.44 oz.

(photo 13 - ESC placement)

There is a cooling air slot through the firewall for the ESC and the ESC has the Welgard “sticker” removed to expose the fins of the heat sink. The receiver battery was Velcroed to the bottom of the hatch, as far forward as possible. The switch harness was installed and the Shadow 3 receiver Velcroed into a convenient position. It was necessary to use a 7” extension on for the Rx battery to allow the hatch to swing out with the battery in place.

(photo 14 - Rx battery placement)

Here is the rundown of measured weights for the onboard radio system.

Onboard radio weight:
Sombra Labs Inc. Shadow-3 “Crystal-Less” RC Receiver w/ 5.5” aileron extension and strain relief button: measured 0.44 oz./12.5g
Welgard 65-amp controller with Velcro: 2.21 oz./62.65g
BP Hobbies 4-cell 700mAh Rx battery with 7” extension and Velcro: 1.94 oz./54.9g
Switch harness & screws: 9.2g
Wing Hitec HS-225BB servo, pushrods, Kwik links, etc: 1.32 oz./37.3g
Fuselage 2 ea. HS-225BB servos, mounting materials, pushrods, etc. 4.32 oz./122.55g
Power Battery Tray and supports: 40.8g/1.44 oz.
Total: 339.9g or 11.99 oz.
Step 17: Charge the 6-cell M1 (A123 Systems) pack
Before charging the pack for the first time, I measured the individual cell voltages. Five of the cells measured 3.30v and one 3.31v. When the unmodified Astro Flight 109 charger finished charging the pack at 1C, 2.3 amps, the display read 21v, 45:55 minutes, 1.105AH. This is slightly “undercharged” for this pack as it should be charged to between 21.6v or 22.2v, but I have found that in practice this works out okay for now.

(photo 15 - side-to-side balance)

Step 18: Side-to-side balance
The fore-and-aft balance was already noted as the CG, as that is how it is commonly used, but the true Center of Gravity is actually a point that may, depending on the plane design, be inside or actually outside of the aircraft structure.
The plane was “slung” to determine the side-to-side balance and it was found that seven 8D finishing nails 2.5” long would be required to achieve this balance. The seven nails weighed 16.9g and were inserted by drilling pilot holes in the right wing tip close to the leading edge and all forward of the “CG.” The nails were secured with glue and covered with white EconoKote.

Weight Notes:
If I have copied all of the weights correctly from my notes, then the ready to fly (RTF) weight should total 2461.65g or 86.8 oz. Finally, I weighed the finished wing and fuselage using my digital scale, which is not as accurate as the balance scale used for all of the above measurements, and found the wing to weigh 705g and the fuselage with everything installed to weigh 1170g for a total of 2475g or 87.3 oz. or 5.46 lb., which is what I’ll use when noting the RTF weight to others.

(photo 17 - finished right rear)

Finished specifications: (more mtr/prop data below)
Wingspan: 54 1/16”
Wing area: 615 sq.in.
Fuselage length: 51.25”
RTF Weight: 87.3 oz.
Wing Loading: 20.4 oz./sq.ft.
Cubic Wing Loading: 9.89 oz./cu.ft. (Cusp between sport and advanced sport)
Initial Center of Gravity: ~3.5” from the wing’s leading edge
Motor: TowerPro/BP Hobbies 3520-7
Prop: APC 12x7 sport (as first flown)
Prop disk loading: 111.15 oz./sq.ft of disk area (63 oz./sq.ft. is average for sport electrics and 79 oz./sq.ft. is average for advanced sport electrics)
Disk loading factor: 1.3 (3 is average for sport electrics and 2.4 is average for advanced sport)
Note: see the September 2007 Ampeer for my personal preferences for prop disk loading and prop disk factors)
ESC: Welgard 65-amp brushless
Battery: 6S1P M1 (A123 systems) harvested from DeWalt DC 9360 pack
Motor data using APC 12x7 sport prop
Maximum RPM: 9390
Static Maximum Amps: 35.8
Static Maximum Watts: 643
Watts in/lb.: ~117
Theoretical pitch speed: 62.2 mph
Theoretical Stall speed: 16.7 mph
Pitch speed to Stall speed ratio: 3.7:1
Watts per cu.ft. wing area: 72.9 (66.5 is average for outrunner equipped sport planes and 84.25 is average for advance sport planes)
Onboard radio system:
Sombra Shadow 3 7-ch receiver
BP Hobbies 4-cell 700mAh NiMH pack
3 each Hitec HS-225BB

Transmitter: Hitec Eclipse 7 7-ch

Prop Selection:
I used Drive Calculator to determine which prop to start with. I selected the motor with 1-deg of timing on the ESC and 6 M1 cells. First I looked at 13” diameter APC props that would pull my target 35 amps. The APC 13x6 sport prop was close with about a 37-amp draw and the APC 13x6.5E showed about a 40-amp draw. (Note: both props may be tried in the future, as they would reduce the prop disk loading to ~95 oz./sq.ft. and have a prop disk loading factor of 1.52.)
Next I looked at the APC 12” diameter props, which I actually purchased so the actual weights are also available.
12x8E 40 amps, 8900 RPM, 679 watts in, weight 24.05g
12x7 Sport 35 amps, 9220 RPM, 617 watts in, weight 44.3g
12x6E 31 amps, 9550 RPM, 551 watts in, weight 23.8g
I chose the 12x7 to be the initial prop because it met my “35-amp” draw and it was heavier than the 12x8E. I wanted the extra weight, not knowing how close the CG was.
I then did a single test of the motor with the APC 12x7 Sport prop capturing 5 data points approximately 5 seconds apart.
Collected Power System Data:
8/14/07
Altitude: 286m/939 ft. Temp: 81-deg F Didn't record other readings, it was sunny and not humid
Battery: New DeWalt pack - M1/A123 6S1P 2300mAh - ambient temp
Prop: APC 12x7 Sport
17.45v, 35.0 amps, 9120 RPM, 610.750 watts in
17.41v, 34.1 amps, 9120 RPM, 593.681 watts in
17.38v, 34.5 amps, 9090 RPM, 599.610 watts in
17.18v, 34.3 amps, 8970 RPM, 589.274 watts in
17.13v, 33.4 amps, 8970 RPM, 572.142 watts in
Average:
17.31v, 34.26 amps, 9054 RPM, 593.091 watts in

New static test 09/23/07 only one run at TOP of pack, 12x7 sport prop and pack in plane made from DeWalt pack.
17.96v, 35.8 amps, 9390 RPM, 642.968 watts in

(photo 18 - front left)

Flying:
Saturday, August 18 was the perfect day to do the initial flights. I arrived at the Midwest RC Society 7 Mile Rd. flying field a little before 10:00 a.m. I was a little disappointed to find that the field had not been mowed in quite a while and the runway grass was very, very long. This field is not as nice as the 5 Mile Rd. field was. The flight line is on the south side of the field with trees at the east and west ends of the field. The trees are not all that close, but still there.
I wanted to get a feel for flying and landing at this new field, so I put up the Sonic 500 for a couple of flights to check out the field and landing approach and the effect of the long grass on takeoffs. I had swapped the Shadow 3 out of the Sonic 500 for a Berg 4 when the Flite 40 was set up. Both planes were range checked at home, so were ready to go when I got to the field. Luckily, the grass was not too thick and I was able to get the Sonic 500 up without it tripping over on its nose on takeoff.
I switched the transmitter to the Flite 40, set the timer for 5 minutes and double-checked all the controls. The takeoff was actually quite good and with just a little flying around it was easily trimmed with a couple of clicks of down and left aileron. High and slow speed flight followed with a few loops and rolls to check the throw setup. Most important was the diving test to check the CG. It was just fine. The plane “feels” very well “balanced” in the air. The landing was a non-event.
The battery was immediately put on charge. About halfway through the charge my three-year-old Marine/Deep Cycle battery gave up the ghost. Figures! I finished the charge using the battery in my truck. At best guess the unmodified AF 109 put back in about 1650mAh.
The timer was reset for 6 minutes for the second flight. I continued to feel out the plane and do several very basic maneuvers. The takeoff and landings were excellent.

I was now ready for the Pontiac Miniature Aircraft Club’s e-meet on Sunday, August 19.
Sunday dawned with rain and temperatures in the mid-50s. Shortly after I arrived at the PMAC flying field the rain abated to a light drizzle. What the heck, I came to fly so I did.
In a short time the drizzle abated to nothing. The ceiling was quite low with planes “ghosting” when reaching it. Hey, keeps it interesting.
Four more flights were put on the Flight 40. While the dive test on the previous day showed the CG to be properly placed, I could not get the plane to do a decent snap or spin. I think that part reason that it doesn’t spin well is the very gentle flying characteristics of this type of fairly thick airfoil, but I’m going to move the CG back a little to see if that helps.

On Wednesday, August 22, I flew the plane to test using an APC 13x6.5E prop. It was 88-deg F at the Midwest field. I set the timer for two minutes, as I wanted to “split the flight” and took off the APC 12x7 sport prop. Having forgotten to start the timer, again, I called for Dave Stacer to get it going for me. After flying for a little over two minutes, I landed and changed props to the 13x6.5E. The takeoff was quite different, as the plane did not “rotate” as nicely as it had been with the heavier 12x7 sport prop. That lighter prop had made a difference in the handling. The plane noticeably had more “pull” in the vertical. After flying around for two minutes, I did remember to set timer, I landed, or I should say arrived. So far, I had greased every landing up to this point. During my “arrival” I heard a crack. I immediately check the motor area as I thought I might have broken the prop. Nope. Upon closer inspection I found the gear blocks had both broken loose. This was a good thing. I had wanted to take them out originally, but had not figured out how to do it. Arrive on the landing field instead of land, that will work.
Actually, there is so little glue on them that they should be able to be pulled out easily with a pair of needle nose pliers.
On landing, I felt the battery pack, and even in the 88-deg F heat, it felt just over ambient, and it has hardly any cooling. The motor felt quite warm, warmer than any time I had felt it before.
Until I get a heavy hub and the weather cools, I’ll be sticking with the APC 12x7 sport prop, although the extra “power” of the APC 13x6E did put quite a smile on my face.

Sunday, August 26 was a beautiful day at the Midwest flying field. It was sunny with light winds and an ambient temperature of about 75-deg F. A great day for flying. The first flight went very well with no problems. It ended with an excellent landing and taxi back to the pits. The pack was recharged and the plane placed on the field for take off. The throttle was advanced and the a click, click noise was heard, but no throttle. The throttle was chopped and tried again. Click, click then silence. When the plane was brought back into the pit area and the hatch swung open, the smell of burned electronics permeated the air. The ESC had gone south.

Saturday, Sept. 1, two flights to put on video tape. Strange vibration heard during both flights that is NOT flutter.

Sunday, Sept. 2, tightened up all I could think of. Still vibration noise. Flew two very normal flights but the noise is quite annoying! I'm going to resecure the ESC, under the battery tray, and secure the other wiring and see if that takes care of the vibration noise. It wasn't there before switching ESCs. (Vibration turned out to be loose wing covering, see Warning near begining of article.)

ESC data:
I have three BP 70A Brushless ESC (http://www.bphobbies.com/view.asp?id...3&pid=B1818513) $35.95 Sept. 7, 2007
Data for all three are presented here:

Dimensions:
Length, including capacitors: ~60mm
Width: ~38mm
Thickness: ~18mm to allow for protrusions on “back”

#1 Wt. as delivered: 55.95g
Wt. w/Velcro & 5 APP connectors: 62.90g
Battery Lead Length: 110mm
Motor Lead Length: 65mm

#2 Wt. as delivered: 56.05g
Wt. w/Velcro & 5 APP connectors: 63.15g
Battery Lead Length: 125mm
Motor Lead Length: 65mm

#3 Wt. as delivered: 56.1g
Wt. 5 trimmed APP connectors: 61.40g
Battery Lead Length: 121mm
Motor Lead Length: 66mm

New Measured Motor/Prop Data: (Oct. 8, 2007)
HXT 42-60/06 #1, APC 13x9 pattern prop
Maximum RPM: 7590
Static Maximum Amps: 35.9
Static Maximum Watts: 622.5
Watts in/lb.: ~114
Theoretical pitch speed: 64.7 mph
HXT 42-60/06 #2, APC 12.5x10 pattern prop
Maximum RPM: 7950
Static Maximum Amps: 36.0
Static Maximum Watts: 647.3
Watts in/lb.: ~119
Theoretical pitch speed: 75 mph

Who is this plane for?
This would be a very good low-wing trainer for someone who has soloed on a high wing trainer at a regular AMA flying field. It is not a park flyer. It is gentle and extremely easy to fly with no surprises for a pilot with good high-wing four-channel experience.
It is for someone who wants to build a “40-size” model on the cheap. The plane was $50 plus $19.99 for shipping. The DeWalt battery pack was $114.98 delivered with 4 cells left over for another project making the cost of the pack’s cells $68.98 plus the cost of a balance plug, power wires and connectors, which means in the low $70 range. The BP Hobbies 3520-7 now list for $37.95 and the BP Hobbies 60-amp ESC (equivalent to Welgard in this review) for $24.95 on August 20, 2007.
It’s for someone who wants to have fun flying basic pattern type maneuvers with a gentle yet responsive plane.
I like it.

Catastrophic Motor Mount Failure

Once the wing “buzzing” was cured, I decided to install the HTX 42-60/06. Because the can is so long on this motor, I chose to install it so that the rotating bell was not turning the prop. The cowl was epoxied to into place and a 1/8” birch plywood front firewall fabricated and epoxied to the now firmly attached former cowl.

Photo 20 shows the attachment

On Saturday, October 6, 2007 I took off and had to do a lot of re-trimming of the plane because the left wing was no longer “sucking air”. About three minutes into the flight the motor and prop parted the airframe. It was “interesting” flying the now extremely tail-heavy plane back to the field. Its “arrival” caused little damage to the airframe. Whew.
The only part found was the firewall with the stator attached. The prop, shaft and bell with the magnets in it were never recovered.

Photo 21 shows what's left of the motor

Upon closer inspection I found that the 1/8” birch plywood had separated in a couple of places and the triangle stock was ripped away. A few of the glue joints had sheared as well. The lesson learned was to use a metal motor mount when mounting a motor in this manner!

Photo 22 shows the birch plywood firewall

Motor number 2 was attached using screws and nylon standoffs. The cowl was rebuilt into a cowl again.

Photo 23 shows the mounting of the HXT 42-60/06 #2
Last edited by Ken Myers; Oct 08, 2007 at 11:41 AM. Reason: updated flight report
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Aug 31, 2007, 04:20 PM
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Ken Myers's Avatar
Good news. On Wednesday, Aug. 29 I ordered two BP Hobbies 70-amp ESCs. They arrived today, Friday, Aug. 31. Great Service! I've got to get them to the dungeon and get APPs on them and give them a try. Looks like this bird will be back in the air for the long Labor Day weekend.
Sep 01, 2007, 06:20 PM
Registered User
Ken Myers's Avatar
Flew a couple of flights this morning with one of the new speed controls in it. No problems. Still loving the heck out of the M1 cells. First flight was 6 minutes and I put back in 1.550Ah according to my unmodified AF 109.

My flying buddy, Dave Stacer shot some video and will be editing it for the Web soon, but it is Labor Day weekend. I'll post it somewhere, if anyone is interested.
Sep 02, 2007, 01:49 AM
<- Balsa flies better ->
wolw's Avatar
Nice work

I like your well documented builds, and you know we always love some video

Peter
Sep 02, 2007, 06:51 AM
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Ken Myers's Avatar
When I put up the build thread, I forgot to post this photo from the Dymond RC site showing what the plane was supposed to look like. I want to ask if anyone around the world might recognize the model? As I said, there was no way to tell who might have manufacturered it.
Sep 02, 2007, 01:23 PM
Got shenpa?
flieslikeabeagle's Avatar
Thanks for the build thread, Ken. I always learn something from your threads (even if it's which models are best avoided. ).

A question, if I may: can you point me at a link or other source of info on prop "Disc loading factor"? I'm aware of prop power loading (watts/area), but have not run into the loading factor in the past.

-Flieslikeabeagle
Sep 02, 2007, 03:05 PM
Registered User
Ken Myers's Avatar
Can't believe I've just spent an hour looking for my original source, but I've been using and writing about it since 1996, so the original article was probably in MAN sometime before then an probably by Andy Lennon, but maybe not. I had several articles in the Ampeer about using it starting in February 1997 and it will be discussed again in the upcoming October issue. I believe I also mention it and how to use it in the current issue, September 2007. Direct link near the top of the page
http://members.aol.com/kmyersefo/

Send me your email address and I'll send you back an Excel spreadsheet with a lot of interesting data that I've collected including disk loading for both electric types and glow types.
kmyersefo@aol.com
Sep 03, 2007, 07:17 AM
know it all
thanks Ken
Sep 03, 2007, 03:21 PM
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Ken Myers's Avatar
Took her out again this morning, Monday, Sept. 3. Went through every possible thing that could be causing the rattle/vibration. Left no stone unturned, I THOUGHT!

First short flight still noisy. Dang. Landed, removed cowl, which I was sure wan't loose. Took off, still noisy!

Just then Dave drove up and commented, "Still making that noise I hear."

"Yep," said Ken in a slightly disgusted voice.

Landed. Taxied over.

Dave said, "How about motor bearing?"

After pulling, prodding and looking and looking, seems that motor bearing(s) might me be shot.

Ah, small piece of loose tape on prop. Tape is used to balance. Remove small piece of tape. Fly again. Still noisy.

Came home and ordered bearings. Shucks. :-(
Sep 07, 2007, 05:15 AM
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Ken Myers's Avatar

Video added


Dave Stacer put together some of the video he shot of the Flite 40 on Sept. 1. You can clearly hear, what I still believe is, the "bad" bearing(s).

The video is here: https://www.rcgroups.com/forums/show...87#post8132494
Last edited by Ken Myers; Sep 07, 2007 at 05:32 AM. Reason: added video link
Sep 09, 2007, 08:08 PM
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Ken Myers's Avatar
I flew the plane again yesterday with the new Boca bearings in it. It was quieter, but not quiet. Tried several other things at the field that I thought might be rattling some. Nothing. Finally came to the conclusion that I may have bent the shaft ever so very slightly on the 8th landing, as that is when the vibration noise started, flight 9. I took the shaft out when I got home yesterday and rolled it on glass and could not detect any bend, but just because I'm running out of possibilites, I ordered a new shaft this morning.
Sep 11, 2007, 11:10 PM
Foam rules
Thatovalguy's Avatar
Ken, check the wheels. They rattled real bad on touch down rolling through the grass in the vid. So in the air they are going to really rattle up a storm. I have that issue with my 60 Extra. The first time it happened I thought the motor was coming out of it. And yes I still need to fix it right but I stuffed a small block of spongy foam up in the wheel pants to fix it that day and never really fixed it proper. What was wild it took about three / four flights before it developed the problem.
Sep 12, 2007, 05:53 AM
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Ken Myers's Avatar
Thanks. That was a thought of mine as well. If it still "rattles" next time I get it in the air with the new motor shaft, I'll snug those puppies up. What is odd is that this "noise" didn't start until after the eighth flight. Actually the new Boca bearings I put in it brought the "noise" level down, but it is still there.
Sep 13, 2007, 07:26 PM
Foam rules
Thatovalguy's Avatar
Yep I had the same issue. The plane was quiet for about 4 flights then I took off and all of a sudden this massive rattle. I chopped the throttle and brought her in thinking the motor was coming apart or something. Running up on the ground nothing at all. Picked it up and ran it up and the rattle was back. One of the guys said wheels. So we stuffed some foam for around the rx in the pants and all was good. Seems like the bearing part of the wheels wore enough to let them rattle up a storm.

Now my big question is how or where do I get a true running spinner for these electrics. Man everone I've tried vibrates, even a Tru-turn spinner. And on a electric it really ruins the smoothness of the package.
Sep 15, 2007, 06:12 AM
Registered User
Ken Myers's Avatar
I put the new shaft in yesterday, Sept. 14. Next I checked the wheels. The tailwheel was really loose on the axle. It wasn't when I put it on. Seems the hole has enlarged some. I've actually tightened up the tailwheel and I've also put some tape on the axles of the main gear which also seemed to have enlarged holes in the cheap Chinese "plastic" wheels.

I'm pretty sure you are right, that the "noise" was created by the wheels and was exacerbated by the motor vibrating a little. I never heard the sound on the ground and don't know if holding it up running would have done any good as the holding most likely would have dampened the vibration.

I had hoped to fly this morning to check it out, but it is very early and the wind is already to an "unpleasant" flying level. I do fly in wind, but it is a 1/2 hour drive to the field and that's a bit much gas for a couple of flights. As I said, I do fly in wind, especially if I have driven a distance to a meet, but its not as much fun.

Hopefully I'll get a chance tomorrow to do it. Next week I'll be very busy, as the wife has the week off and I'm sure she has "plans" for me. ;-)

My only plane with a spinner is my ElectroFlying Fusion http://www.electroflying.com

It is an aluminium Tru-Turn on an AXI 4120/18. No vibration problems with it. Whisper quiet. All of my other planes have the little "spinner" nut on them. I gave up on Du-Bro and Goldberg spinners twenty plus years ago when I switched to all electrics. I have been tempted to try some of the Maxx Products spinners or the ones that Hobby Lobby sells. I know there are planes that have to have spinners to look right or be scale looking. So far, I've kind of stayed away from them because of the spinner issue.

Keith solved the problem nicely. He makes and balances his own. Unfortunately, I do not have that skill. Luckily, if I really, really needed a spinner for a project, I could drive over to his place in Ann Arbor and have him show me how to do it.
Last edited by Ken Myers; Sep 16, 2007 at 05:03 AM. Reason: Forgot to answer about spinners


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