Greg Covey

Hi,

After seeing this great looking plane in the magazine and on-line promotions, I decided to review the ParkZone Super Decathlon RTF plane. The covering scheme not only looked fantastic but it is just the right combination of colors that I love to see for great flying orientation!

You won't need anything to get this plane up and into the sky. ParkZone has included everything right in the box.

Here are the features of the [link=http://www.horizonhobby.com/Shop/ByCategory/Product/Default.aspx?ProdID=PKZ1400]Super Decathlon[/link]:
[ul][*] Realistic features and scale appearance[*] Proportional elevator, rudder, and throttle[*] Mode-Change Flight Control System allows users to fly in two modes[*] All components needed for flight are included in one box so you can get up and fly fast![*] Docile flight characteristics allow you to do large field moves within a small field of space[*] Reusable 27 MHz proprietary radio system with Rx/speed control module and separate 5-wire servo motors[*] One-piece wing with scale wing struts[*] Gear-reduced 370 class motor with large propeller[*] Stainless steel landing gear, including wheel pants
[/ul]

Specifications:
[ul][*] Wing Span: 35.4 in (900mm)[*] Overall Length: 25.3 in (640mm)[*] Flying Weight: 16oz (450g)[*] Motor Size: 370 class with gearbox[*] Radio: Proportional 3-channel FM[*] Trim Scheme Colors: Red Fuselage - Blue Trim with white borders[*] Recommended Battery: 8.4 V 600 mAh Ni-MH[*] Throttle: Proportional[*] Approx. Flying Duration: 13 minutes[*] Approx. Assembly Time: 5 minutes[*] Transmitter Range: 2500 feet (762m)[*] Available Frequencies: 6 Frequencies on 27 MHz[*] Smart Trak: No[*] X-Port: No[*] Charger: DC Peak[*] Landing Gear: Stainless steel with wheel pants
[/ul]

Greg Covey

Everything you need is supplied in the box. This includes the RTF plane, transmitter, flight pack, peak charger, and support hardware. The box even includes AA-size batteries for the transmitter!

Greg Covey

It takes longer to charge the 7-cell, 600mAh NiMH flight pack than it does to assemble the plane. I simply installed the eight AA batteries into the transmitter and then pushed on the pre-finished landing gear into the fuselage bottom.

The control linkage comes ready to go on the lowest throw setting. Since the transmitter has a dual-rate switch, I decided to increase the throw range by moving both the elevator and rudder clevises to the 3rd hole from the end of the control horns. The clevis was re-adjusted outward (by unscrewing it a few turns) to re-center the control surfaces after first centering the transmitter trim tabs.

Greg Covey

A look inside the fuselage reveals the radio components. The ESC is integrated with the receiver in an assembly that can be pulled up for changing the jumper settings. The Super Decathlon stock settings were what I wanted to use so no jumpers needed to be changed.

Jumper settings were provided for the following features:

Jumper 1- Mix of Elevator and Rudder:
You can add the jumper to utilize software that will allow a slight mix of elevator and rudder. In this mode, when rudder input is given, a slight amount of up elevator is added. By doing this, the nose of the airplane will be more likely to “stay up� when rudder input is given. This can be of great help to pilots that are transitioning from 2 to 3 channel aircraft and are not used to pitch control.

Jumper 2 - V-Tail/Standard Tail:
Tail control: Your Super Decathlon comes with the plane set for conventional “T� tail control. If you remove the jumper, you will switch the control to “V� tail function. This would allow you to transfer the radio system to a “V� tailed aircraft, such as the ParkZone™ Slo-V™, or elevon equipped aircraft such as the ParkZone™ F-27 Stryker™.

Jumper 3 - Auto Cutoff:
Auto Cut-Off: Your Super Decathlon comes with the jumper included in the third port. This sets the auto cut-off to function with 6-8 cell Ni-MH battery packs. If you remove the jumper, the auto cut-off will function with a 9 cell Ni-MH battery pack or a 3S LiPo battery pack.
When your Super Decathlon goes into auto cut-off, prepare to land immediately. You will maintain control of steering and pitch, but not have access to throttle at this time. You can “blip� the throttle to try to re-arm, but only attempt this once as you are preparing to land.

Greg Covey

I was happy to see that the flight pack was positioned near the CG. This meant that a change in the pack weight by changing cell type or battery technology would have little impact on the balance.

Although the plane was suppose to weigh 16oz (flying weight), I measured 15.6oz for the empty plane and 3.6oz for the 7-cell, 600mAh NiMH pack. My plane weighed 19.2oz ready to fly. This additional 20% in weight could play a factor in how well the plane performed with a geared Speed 370 (aka Speed 300) power system.

Greg Covey

My Super Decathlon was ready to fly before the battery finished charging. It looked great right out of the box and I was anxious to give it a test fly.

The wing measured 35" by 6" so the wingarea was about 210 sq. in.

The wingloading would be 19.2/(210/144) or 13oz/sq. ft. which is a bit high, but functional, for a geared Speed 300 plane.

Greg Covey

I flew the Super Decathlon on a cold grey day with a moderate wind. The temperature was around 35 degrees F. The wind seemed to change directions and the speed was 5-15mph.

On my maiden flight, I was both impressed and a bit dissapointed. I was impressed that the plane flew straight with neutral trim settings on the control surfaces and transmitter trim tabs. Since most of the flight was at full power, I was a bit dissapointed in the power system.

Although I knew that the plane would fly better under nicer weather conditions, I decided to investigate the power system.

Here are some photos from the maiden voyage.

Greg Covey

The prop removes easy by pulling off the spinner and unscrewing the nut.

The cowl can be removed with a single screw after first peeling off the black sticker. The side decals must be either cut or peeled back. I choose to cut mine at the cowl edge.

The power system looked neat and easy to repair. Note that the motor is reversed so that it can still spin in the forward (CCW) direction in the gearbox. I thought this was a clever design overall.

A 0.1oz nut was wedged onto a plastic post in the front of the cowl. This was most likely a fine adjustment to the CG. Since my plane flew perfectly straight when the control surfaces were at neutral, I feel that ParkZone did a good job in both balancing the plane and obtaining the correct thrust angle.

Greg Covey

The motor is mounted to provide both down thrust and right thrust.

I noticed that my prop was not perfectly balanced so I added a small piece of masking tape to the back side of one blade. This eliminated the "double vision" seen when watching the prop from the side at full throttle and also reduced the vibration felt from the fuselage.

Since I could not easily measure the current with the 7-cell, 600mAh NiMH pack, I decided to put the front end back together and give it another test flight. Perhaps I would see more power once the NiMH pack and gearbox had a few flights on them.

75lover

I just got a Super Decathlon. Good review. What do you mean you were dissappointed in the power system? It doesn't go fast enough? ??

Rat1

It runs the same power system as the ParkZone J3 cub and in my opinion the cub is slightly under powered in stock trim ie it is too heavy for the amount of power you have available. Now the Super Decathalon is heavier then the cub by a little bit and that little bit is alot when it comes to flying models. So yes the Decathalon will fly but you will need full throttle to keep it in the air. maybe a dif prop, gws 9070 or gws 0947, might help it out a bit. It might rub the ground on take off or landing but you could always hand launch and land it in the grass.

andy98801

I agree use a GWS 1046 I work for my LHS and got one when it came out. In the beggining it crashed alot due to me not giving enough throttle and stalling, changed the prop and using a 2s lipo taped to the bottem this thing flew like a dream. I love it. I am going to try my 3s lipo should give a very noticable power boost to eliminate the under power situation. One thing i do have to say is that it is very durable. during a crash either nothing happens or the wings pop off. Nothing broke so far after about ten hard "landings"
Great plane overall. Later
Andy

dhsc19

Anyone having problems with very jittery servos on the Decathlon RX?

Greg Covey

Thanks for the suggestions. I'll find a way to get my watt meter in-line to measure the current differences on the various setups.

No problem with servo jitter here.

Greg Covey

I found a way to connect my watt meter using a series of adapters. The stock ParkZone connectors are not my normal choice for other planes.

The stock setup measured as follows using the 3.6oz, 600mAh, 7-cell pack:
[ul][*] 5.8amps, 43 watts, stock prop (perhaps an 8x6)[*] 5.8amps, 43 watts, GWS 9x4.7 SF prop[*] 7.0amps, 47 watts, GWS 10x4.7 SF prop
[/ul]

In essense, the stock setup, although properly designed, is a bit low in power for this plane at 36 watts/lb. The change to a GWS 10x4.7 prop provides an additional 10% more power but also taxes the motor more. This may be ok due to in-air unloading.

I also tried a few 2-cell Lithium packs with the GWS 10x4.7 prop:
[ul][*] 6.3amps, 40 watts using 3.0oz Kokam 1500mAh pack[*] 6.3amps, 40 watts using 1.6oz ThunderPower 860mAh pack
[/ul]

Of the two Lithium packs I tested, the lighter weight ThunderPower pack reduces the flying weight by 2oz or about 11% at 17.2oz.

While the plane would certainly fly easier in a calm summer morning, the cold temperatures in a New England winter season put greater demands on the power system. Perhaps a GWS 10x8 prop combined with a lighter 2-cell Lithium pack would supply the easiest upgrade for increased power and reduced weight. The upgraded power system could deliver about 50 watts/lb. with a lighter wingloading.

AgCat1982

Greg, in what way are you implying heavy demand due to the cold weather. Cold battery? The air is thicker when cold and a plane flies better, normally. That's why I am asking. I know cold batteries do not supply as much power.

Thanks.

GeneR

Greg,

Did you purchase the model you reviewed, or did Horizon provide it? I only ask because of my experience which I will relay below.

I purchased two Decathalon models about 2 weeks ago. In addition I bought an extra fuselage with electronics and an extra rx directly from Horizon.

I notice that both servos jitter constantly whenever the flight battery is connected. Now, let me say that I have been flying RC models for 25 years, have a basement full of other planes and 2 Slo V's, a Stryker, and a J3 from Parkzone and none of them have the servo jitter problem. I fly 27MHz all the time and so interference here is not a problem either. The ends of the arms move about 1/16 of an inch each way constantly even with the push rods disconnected, tx moved far away, etc.

I checked both boxed models which I purchased and both do exactly this same thing as does the Decathalon rx I purchased separately and the fuselage with electronics. I then went back to the LHS and their models also jitter to beat the band.

I called Horizon last week late and their product support guy told me the servos should not jitter and he sent me another rx to try. The new rx is the same as all the others. I simply hook it up on the bench and the servos jump all over the place.

Clearly this is not right. I am certain that all this movement, even if it does not effect the range of the rx (I am afraid to fly the plane like this) will certainly wear out the servo feedback pot. I suspect it will be noticable in the air as well.

I will try to contact Horizon again tomorrow. This is clearly a problem with the rx as I can move my J3 rx into the Decathalon and it does not jitter and I can put the Decathalon rx (any of them, I have a bench full<g> in the Cub and the servos now jitter.

I am just trying to see if all these rx's do this (maybe they sent you a prototype which worked) or if there are some which work fine.

Thanks
Gene

Mountain_Flyer

GeneR , mine "had" the servo jitters.. ive been flying it every chance ive had for about two weeks now .. no more servo jitters
it progressively went away the more i few it now there just a very faint hum ( same sound my ABX makes and it has about 100 flights on it ) so "maybe" the jitter will go away with a little use

Greg Covey

In cold weather, a plane only flies better if it has sufficient power. The thicker air makes the Super Decathlon look weaker and there is no rising warm air to help lift the plane. The colder temperatures also reduce the flight pack output. This is mostly on NiMH and Lithium packs. In the cold temperatures, a slight breeze will just about stall the Super Decathlon.

Servo jitter can be caused by many reasons. On 27MHz, I would first suspect outside interference. Next, I would try increasing the distance between the transmitter and the plane to see if it changes the amount of jitter. The lower cost servos could also have some bad pots so they don't zero properly. Lastly, I would try replacing the receiver itself or just the crystal and if this failed, try replacing the transmitter. If it all fails, go back to my first suspicion.

Good luck!

GeneR

Ok Greg,

Thanks for the help, as I said in my post I knew all of those things and tried them. It just seems odd that I could have 5 defective receivers... I am sending the whole mess back to Horizon. We will see what they think. Hopefully they can find 5 receivers like you got that don't jitter.

Gene

dmhines

My Decathlon has the jitters as well as a friend of mines. It does not seem to affect the flight so maybe they are just getting swamped with the transmitter being too close -

mectf

Why does this thing appear to be so much more of a turd in performance than the J-3? The J-3 doesn't appear to have any of the problems this thing does. I haven't red the comparisons back to back but it obviously shares some parts and appears to be pretty much the same plane but in a little different style and color.. Whats up wit dat?

GeneR

I have had the transmitter from right next to the rx to half way across the yard. Still jitters. Spoke to Horizon today. They say should not jitter. I indicated I had 5 rx's that jitter and have had a number of folks on the internet tell me that as well. They deny any knowledge of the problem.

Hard to imagine they did a QC on some of these and did not see any problem. Well, I am going to send back all the receivers. The jittering is not right. None of the Slo V, Stryker, or J3 Rx's jitter at all. I have said all along I love my Parkzone gear, they just need to make these receivers right.

As far as the flight performance, I have not flown mine but once I send the rx's back I will put a J3 receiver in it and fly it. It has a thicker fuselage and is heavier so I expect more drag.

We will see.

Gene

combatroy

Hello all -

I'm kind of a noob but I noticed some jitter sound on my Aerobird extreme and here is what I discovered. The more tension I had on the servo's (via the fishing line) the louder it sounded. I loosened the tension a little and the servo jitter went away.

Help this helps.

Ur_Dad

Hey Greg - I have the Cub and haven't yet flown the Decathalon, but I've noticed the same thing as you with the twitching servos. You will notice, however, that this only happens when you first plug in the battery and the transmitter is powered up and right next to the plane. As soon as you put a few feet between the radio and the plane (i.e. when you take off), the twitching stops and there don't seem to be any related problems when flying. I wouldn't worry so much about it.