Dynaflite Super Decathlon 89" WS

[Carl Petersen]

I can't find any info on an electrified version of this plane. Anyone have a suggestion on motor/battery specs?

Wingspan:89 in (2261 mm)
Wing Area: 1237 in² (80 dm²)
Weight:16-18 lb (7258-8165 g)
Fuselage Length: 69 in (1753 mm)

I'm thinking Hacker A60-16L / 24x12apc-e / 10S4P-8000 but that might be overkill.

[Sabrejock]

Carl: I built mine to fly on E-powr, but that was round cell (36) and astro 60 beltdrive days. I'm sure there will be better systems nowadays. However, when I switched it to gasoline, I can tell you that a 16x10 CF Bolly at 9500 rpm is what will make the plane do well. You can reverse compute those numbers for Watts needed and maybe go from there. Cheers, Tex.

BTW, I took 3 lbs off the box standard airframe without much trouble. T.

[cooper998]

Perfect timing, I have one "On the Bench" as I type. The fuselage has been lightened by about a pound but the wings are heavy due to the heavy wood used by Great Planes (Dynaflite, GP Brand, Top Flite, Hobbico, etc), I could easily build the wing at half the weight if I substituted lighter weight quality wood. Right now I am expecting a 7~8 pound finished weight without motor, esc, and batteries then add about another 4 pounds should get me flying at 11~12 pounds all up which is a couple of pounds under the recommended weight. Many gas versions are flying at up to 20 pounds without problems. I will be using an Axi 5330/18 on 8s2p 8000mah pack spinning either a 17x10 or 18x10 Apc e prop. Its the same combination I used in my dearly departed Sig Rascal 110 (http://www.rcgroups.com/forums/showthread.php?t=685836) so I know it will fly with authority.
Smaller motors will work fine also, I just happen to have the 5330 but a 4130/20 on 8s spinning a 16x8 prop will knock about 2 1/2 pounds off the total weight so again it should fly fine.
The Hacker is an excellent motor with plenty of torque, but you are right in thinking its overkill but then again so is mine somewhat. Look into less motor and battery, low amps high voltage and you will have a sweet flying plane.
Good luck with your and keep us posted on your progress.

cooper998

[Sabrejock]

For starters, I used balsa spars. Make sure your strut hard points are really functional. I "picture framed" the ply fuse sides and inserted light balsa. The three pieces of 1/4 ply wing joiner: I scrapped two of them and used just one. I even hollowed the wing tips, labour of love, because I might have saved two ounces. But hey if you want the plane to fly better than anyone elses that's what you do.

I didn't sheet the tail feathers, sanded everything to the n'th degree. I plugged the tail servos in at the back (no pushrods). I used UltraKote covering. All this made a superb flying plane. Tex

[Carl Petersen]

Thanks for the info guys.

Looks like I could get away with an A50 if I shed a few pounds off the kit. Getting the CG right could be a little work.

I've been looking for something to build over the next few winter months and this looks like fun. Just ordered the kit :)

We need pictures.

Thanks again.

[cooper998]

For starters, I used balsa spars. Make sure your strut hard points are really functional. I "picture framed" the ply fuse sides and inserted light balsa. The three pieces of 1/4 ply wing joiner: I scrapped two of them and used just one. I even hollowed the wing tips, labour of love, because I might have saved two ounces. But hey if you want the plane to fly better than anyone elses that's what you do.

I didn't sheet the tail feathers, sanded everything to the n'th degree. I plugged the tail servos in at the back (no pushrods). I used UltraKote covering. All this made a superb flying plane. Tex
Sabrejock,
Not sure if we are talking about the same kit or not but my Dynaflite Decathalon uses an aluminum tube wing joiner and the tail doesnt call for any sheeting whatsoever,did you by chance have a different kit? The online manual for my kit can be found HERE (http://manuals.hobbico.com/dyf/dyfa3035-manual.pdf)

cooper998

[GWRIGHT]

Carl,.. I use the 18L on 12S with that prop and have full 3D capability with a 16+ lb plane. It's 4+ Kw. I think dropping to 10S and maybe a 20 or 22 inch prop would be nice for your setup (assuming you don't want to hover a decathlon <G>). I would go for the 18L, not the 16L. For non-3D flying and think the 16 turn motor would be way overkill.
I can't find any info on an electrified version of this plane. Anyone have a suggestion on motor/battery specs?

Wingspan:89 in (2261 mm)
Wing Area: 1237 in² (80 dm²)
Weight:16-18 lb (7258-8165 g)
Fuselage Length: 69 in (1753 mm)

I'm thinking Hacker A60-16L / 24x12apc-e / 10S4P-8000 but that might be overkill.

[Carl Petersen]

Thanks Gary, great advice as usual...

[cooper998]

Carl,
here is a shot of my current motor setup, Axi 5330/18. I may be switching this out to a Scorpion 4025-16 since I will be needing the Axi for a 1/4 scale Lanier Taylorcraft which is scheduled to hit the building board next month.
I make my own aluminum mounts, the standoffs are drilled for 8-32 threaded rod and 2 5/8" long. The motor box is 1/4" ply reinforced on the insides with basswood tri stock and finally epoxied and screwed to the stock firewall.


cooper998

[Sabrejock]

Sabrejock,
Not sure if we are talking about the same kit or not but my Dynaflite Decathalon uses an aluminum tube wing joiner and the tail doesnt call for any sheeting whatsoever,did you by chance have a different kit? The online manual for my kit can be found HERE (http://manuals.hobbico.com/dyf/dyfa3035-manual.pdf)

cooper998

It sounds as if they've done an upgrade. Good. Tex.

[Carl Petersen]

Copper998

Nice work. Great way to make a very solid mount.

Still waiting for my kit so your way ahead of me. Any gotches you've found along the way?

Thanks

[cooper998]

Copper998

Nice work. Great way to make a very solid mount.

Still waiting for my kit so your way ahead of me. Any gotches you've found along the way?

Thanks
Other than the crappy three piece cowl and some heavy wood the build is pretty straight forward.
I do plan on changing the elevator setup from two servos to one and add a wire joiner to the two elevator half's. The stock setup is fine but would require either a reversed servo or computer radio mixing to get it working in the right directions. I am using 100oz torque servos so one is more than enough to do the job.
Check your wing sheeting and ribs for weight and density and seperate them as equally as possible from left to right so you dont end up with one wing heavier than the other.
oops almost forgot, I used a 1/4" 5 ply landing gear plate instead of the whimpy 1/8" plate supplied in the kit.


cooper998

[Carl Petersen]

I thought as much and ordered a fiberglass cowl and wheel pants from Fiberglass Specialties at the same time.

Thanks

[Carl Petersen]

Carl,
here is a shot of my current motor setup, Axi 5330/18. I may be switching this out to a Scorpion 4025-16 since.
--snip--
cooper998What would you run with the 4025-16? Scorpion_Calc says 8S with an APC 16x12 is about 2KW at 75 A. Can these motors be pushed further?

[cooper998]

Carl,
I am planning on running a 16x8 Apc E prop which puts the amps at just under 60 at wide open throttle. The 16x12 is way too much prop and is not efficient for this type of plane. I fly scale aircraft in a scale manner and with a pitch speed of 63mph is still a bit fast for a 1/4 scale model. The 16x12 gives a pitch speed over 85mph which is way too fast for a 1/4 scale model. Motocalc predicts the 16x8 will give sufficient thrust to hover or perform any aerobatic maneuver so that will be my starting point with props.

Scorpion rates this motor at 75 amps continuous and I have no doubt it will survive but... I don't think it needs to be pushed that hard. I have had great results with other Scorpion motors and hope to have the same results with this one.

If I have some time tomorrow I will post some pics of my battery access hatch I added to the bottom.

cooper998

[Carl Petersen]

Copper998,
For some reason I missed all the info on the Scorpion line of motors until I read your post. They do look good and with a competitive price. I'm going to order a couple and check them out. Thanks.

How many cells on that 16x8?

Look forward to the battery hatch pics.

[cooper998]

Here's a few pics of the bottom hatch I fabbed up to allow quick battery removal without having to remove the wing. I started by making a couple of new formers to sit an inch and a half in front of the landing gear, one was to hold the sheeting and the other was for the hatch. I moved the front former further forward and also cut the bottom of the firewall to allow the battery tray to angle in. I still need to fabricate the actual tray once I have all the structure done and covered so I can get the C/G correct without having to add ballast anywhere.
I am going to use 2 4s 5000mah packs in series or possibly 2 sets of 4s2p packs in series for 8000mah, i wont decide till the plane is almost done. I have the 4000mah packs now and would have to order the 5000's if I decide to go that route. Either way the hatch is big enough to provide enough clearance to install and remove the packs.

cooper998

[cooper998]

My Scorpion Motor showed up today and with nothing else to do I fabbed up a new mount so that I can interchange the motors if I feel the need. The back plate is 6061 T6 aluminum with 3/4" long 1/2" diameter aluminum standoffs.
I sure am glad I never sold my lathe and mill :D

Merry Christmas everyone,

cooper998

[Carl Petersen]

Looking good! Excelent idea for the hatch. I hope you don't mind if I copy it :)

Also the motor mount. I should have one of the 4025-16s after the holidays to play with.

[cooper998]

Carl,
Any updates on your Decathalon? I have been busy with other projects and still haven't finished mine. I have decided to switch my battery thoughts over to A-123 cells, with two 10cell packs providing slightly higher voltage the extra weight wont be a concern. The capacity is a little less than using the lipos but the recharge time is way faster.
I should be finishing up mine in the next couple of weeks, with so many projects lined up I need to get crackin'.

cooper998

[Carl Petersen]

I'm still finishing up another project but the Decathlon is next in the queue. I ordered a fiberglass cowl and wheel pants which should be in by the end of next week. That should spur me on.

I've been thinking about using the A123 cells since I upgraded the software in my TP charger. Where are you getting yours? Two packs should give you about 4600mah, right?

[Sabrejock]

I've been using the A123 in a 2P config for quite a few cycles. I pull about 70A total and each pack is really idling. No heat gain at the end of the flight. A true 4600 MAh is available, but don't rely on it because when it decides it's had enough, it calves. Tex.

[cooper998]

Carl, I just ordered my packs from Toolking.com. Two pack came to $228 with the shipping. I just need to strip them down and add some balance taps and connectors. At less than half the price of lipos I can deal with a little less capacity, 4600 vs. 5000.
My Extrema charger already works with the A-123 cells and I have a set of their new balancers coming any day now.

Tex,
I have seen fellow flyers use the A-123's and after a couple of flights they get accustomed to the rapid dump at the end of its charge. I am hoping to get several short flights in and work up to max flight time so that I can judge its duration and work backwards from there. I really don't want to dead stick if I can avoid it,

cooper998

[Carl Petersen]

cooper, which packs did you order from ToolKing?

[cooper998]

Carl, follow this link, http://www.toolking.com/dewalt_dc9360.aspx

I will be breaking down the Dewalt pack and setting up the cells into 4 separate 5s packs so I can use them in other smaller planes I have as well.

I have seen them cheaper on E-Bay, but I have read reports about ToolKing and he only sells new factory packaged batteries unlike some dealers on e-bay who sell refurbs as new.

cooper998

[Carl Petersen]

Carl, follow this link, http://www.toolking.com/dewalt_dc9360.aspx

I will be breaking down the Dewalt pack and setting up the cells into 4 separate 5s packs so I can use them in other smaller planes I have as well.

I have seen them cheaper on E-Bay, but I have read reports about ToolKing and he only sells new factory packaged batteries unlike some dealers on e-bay who sell refurbs as new.

cooper998Thanks, I'll check it out.

[Carl Petersen]

So I've started this project and I just have to report that the Dynaflite kit is one of the better kits out there. The wood is a tad on the heavy side but more than makes up for that on the quality. I haven't enjoyed building a plane as much as this since I built Gary's E3D-63 and that was fun.

I'm going with cooper998's suggestion using a Scorpion 4025-16 (2000 watts), a CC 85HV controller, and a ten pack of A123s. Should be enough to keep it off the ground.

If you're looking for a project that's on the larger side give this one a look.

Thanks to cooper998 for inspiration and pics.

Carl

[cooper998]

Glad to hear you have started, I agree on the quality of the kit its definitely one of the better offerings from Great Planes/Dynaflite. I have been doing some final sanding on mine before I start covering. Still need to finish the cowling, its been to0 cold here to do any painting.

cooper998

[Carl Petersen]

I went nuts and bought the fiberglass cowl and wheel pants. The excuse is it will get me in the air quicker.

I've been thinking about covering... I might try some coverite to get that cloth look but I haven't used it before. How are you covering yours?

Carl

[Sabrejock]

I've been thinking about covering... I might try some coverite to get that cloth look but I haven't used it before. How are you covering yours?

Carl

Next time you're at an airport check out the paint jobs on fabric covered aircraft. You don't see any "cloth look" if it's been done right. Tex.

[cooper998]

I will be using a combination of Pearl white and teal monokote with the black stripes on the bottom and white star bursts on the top. I looked at the glass cowl prices and could not justify the costs since I was trying to keep this plane "low budget" which is the main reasons for the monokote (I already had plenty). The cloth covering which may look better as a model may not be the lightest way to go, coverite is very heavy compared to film coverings. Having seen several full scale Decathalons the weave in the cloth is barely visible and the covering looks amazingly like "full scale" monokote or similar film covering. Either way I am not looking to build a true scale model, just something to fly for fun.

cooper998

[TaSaJaRa]

I am new to doing a full kit... So I have a newbe question.
What is a good building surface to build on?
I was thinking of getting a hollow door to use the "T" pins on , this sound ok?
I also have made a few of the A123 packs. They are a bit more in weight, but you can charge them much faster, along with less cost.

[cooper998]

TaSaJaRa,
I would recomend a solid core door since over time the hollow core flexes and bows. If using pins is important (I don't) you can then use either ceiling tiles or Homasote board on top of the door. Homasote is a pressed paper product and comes in 4x8 sheets and ceiling tiles are normally 2x4 and not quite as smooth as the homasote.

cooper998

[Carl Petersen]

cooper998,

I've got to pick up some servos. Out of curiosity which servos did you use?

[cooper998]

Carl,
I am using Futaba 3305 metal gear servos, they have worked well in all my recent large planes and I have bunch on hand from my dearly departed Rascal 110. With 99 oz. in. of torque they are a bit overkill on the elevators and I may switch those to dual Hitec 635hb servos at 69oz each.
I havent had too much time into mine, too many other "things" occupying my time lately.
Any pictures of your progress?

cooper998

[Carl Petersen]

The reason I'm asking is that I have a few JR DS821 servos at 88 oz/in left over from another project and I'm trying to convince myself that they would work here.

Have you checked the CG yet? Where did you mount the elevator servos?

I'll post some pictures later.

Carl

[Carl Petersen]

Here's the progress to date. I think I'll start the fuse today just to get a break from building wings. I need to go back and look at your hatch design.

Carl

[cooper998]

Carl,
Any further progress?
After finishing my Cherokee sailplane I dove back into the Decathlon and have it just about ready for covering. I decided to add a tow release for aerotowing since our club is going to need as many tugs as possible this summer.

Cooper998

[Carl Petersen]

Hi cooper,

Very nicely done! I've got everything framed up and all the covering material in house. I've just been finishing up some other stuff waiting for some nice sanding weather, I like to do it outside, and it will be covering time as well.

Tow release looks nice and strong.

[Carl Petersen]

Hi Coop,

In the best tradition of "monkey see monkey do" I'm going to put a tow release in my Decathlon. Did you fab your own or was that a bought part?

Covered yet?

[cooper998]

Carl,
That is a custom fabbed piece by me. It was originally made for my Rascal 110 which bit the dust last year. I am fortunate to have a small lathe and mill (one of my other hobbies) and I can whip them out in a few hours. A commercial unit is made by a guy named Ben Diss who is a member on this forum, his price is pretty reasonable too.
Unfortunately the wings still need to be covered and it will be ready for a maiden.

cooper998

[Carl Petersen]

Thanks, I'll give Ben a holler. I've got a small lathe but I often wish I had a mill as well. Post some pics when you get a chance. I bet it looks real nice:)

[Carl Petersen]

Got my tow release from Ben Diss. Such nice workmanship I thought I would give him a plug here in case anyone else is looking for one.

[cooper998]

Finally flew my Decathlon this morning. Three flights and all is well except for having to change the receiver battery (drained too quick). I had originally intended to use A123 packs but in order to get the capacity needed it would add too much weight to the plane. I flew this morning with 8s 5000mah lipos and total weight of the plane is right at 14lbs.
I had originally intended to use a Scorpion motor but found I needed to add weight to the front to balance the plane so instead I put in the AXI 5330/18 from my dearly departed Rascal 110.

First flight she tracked straight and lifted off at 1/2 throttle. I checked the trims (only two clicks of down needed) and proceeded to check slow speed flight as well as stall characteristics. All was well as she slowed beautifully and when she did stall it was a slight mush down but straight ahead. I brought it in for a two bounce landing and checked the motor and batteries, both just warm to the touch.

The second and third flight were uneventful and I tried some mild aerobatics as well as a couple of full throttle climbs to simulate aerotowing. She has more than enough thrust for towing and the true test should happen tomorrow afternoon. Hopefully I will have some pictures tomorrow also,

cooper998