JunkMan304

My Feedback: (3)

Whta would be the best performance 4-stroke or gas engine for the Dynaflite Giant Super Decathlon? Anyone?


Thanks,
Kevin

Rcpilot

My Feedback: (78)

Gas. 40--50cc

Rcpilot

My Feedback: (78)

I should clarify my last post.

A 4-stroke glow engine will most likely put out more power than a gasser of the same displacement and it'll be lighter.

A 4-stroke glow engine big enough to fly this plane will also eat fuel at a rate thats going to leave a huge hole in your wallet.

A gas engine will be a lot more user friendly. Adjusting the needles on a gasser is not hard--just a teeny bit different than a glow engine. Once you set the needles on a gas engine--forget about it. Your done messing with the carb. No need to adjust it every day.

A gas engine will not use anywhere near the fuel that a glow engine will use. Gas is cheap. Figure about $4 per gallon by the time you add the 2-stroke oil. Compare that too the cost of glow fuel. Glow fuel costs about $15 per gallon. Thats 4 TIMES the cost of the gasoline--and you'll get TWICE the mileage out of the gasoline. So, really--a glow engine costs about 8 times as much to operate as a gasser.

The cost difference between a gasser and a glow engine big enough to fly this plane will be negligible:

A Saito 2.20 costs around $500. The GK version costs about $525.

You can buy a Zenoah G-45 for $400 NIB or sometimes you can get them NIB for $300--$350 on Ebay. Buy one on Ebay and slap an electronic ignition on it for $125 if you want. Or leave it stock. Either way will work.

You can buy a ZDZ 40 for $525 and then the muffler costs between $60--$100 depending on which one you want.

You can buy a 3W-42 for $530

You can get an MVVS 35cc for $440

You can get an RCS 180 (30cc) for $440

ALL these gas engines will fly the Dynaflite Decathlon. And they are all the same price or cheaper than a Saito 2.20.

Who cares about the weight? It's not a 3D plane. It's got enough wing area to carry an extra 15 pounds of payload and still fly with a 40cc gas engine. The weight of a gasser won't be more than an extra 1/2 pound AT THE MOST.

I want to build one of these and put a G-62 on it--but I also want to be able to fly it in IMAC--so the extra power will be needed.

RCVFR

My Feedback: (7)

Maybe you can elaborate on your idea of "best" performance? What do you want to do? I run a G38 on mine, and I think it's about ideal. My plane flies a bit hotter than scale, but I like to fly it close to scale because it looks so good that way. Flinging it about is not very satisfying and makes it look more like a toy than an airplane. To each his own.

Kmot

My Feedback: (24)

I am canvassing airframes for a FT-160 twin and I was wondering if it would fit inside the cowl of this model?

beepee

RCpilet has good points well presented. I will add a couple regarding the SD: Mine (at least) came out tail heavy so a little extra weight in the engine was not a problem. I used a Quadra 42 and am very happy with it. I have also found that the 18" prop is about maximum without other modifications. Still get a few prop strikes when I really shouldn't.

Great bird, have fun!

Bedford

Dave G

My Feedback: (1)

Kevin, I picked this model for my first gasser. I'm using a 25cc conversion from GCBM R/C. This combination will have plenty of pep and will be be a bargin to fly over any of my glow powered models. I'm getting really sick of the $20 per gallon glow fuel. While there isn't a nicer sound than my OS-300 twin in my Pitts, I think I'll enjoy this economy minded plane alot. I don't think any appropriate size 4 stroke twin would fit inside the cowl. I could be wrong, but the firewall is only 6-3/8" wide.

Here's a few pictures for insipration. The 3rd one is the servo operated kill switch and the throttle servo. I'm already planning on a smoke sytem. There's plenty of room in the cabin with the elevator and rudder servos mounted aft.

Pardon the clutter in the photos, but the mess grows and completion nears!

mikeboyd

I have been working on mine for over two years, off and on. It is about 90% complete, covered, just needs final trim, painting and electronics installed. I opted for monocote and a Magnum 1.8 glow. Luckily I only pay about $11.00 a gallon down here for fuel for big glow engines. We will be having a Cub type fly-in next spring in Central Texas, where these planes will qualify to fly. I will post the dates, once we get everything finalized by AMA and my club.

I will be co-cd'ing with a friend, so now have to get this one finished, test flown and trimmed before the event. Just kept putting together too many ARFs and let this one set, but promise to finish in the next few months. Should weigh about 15 pounds, since I am keeping weight down by not being too bent on scale additions.
When I started this, we didn't have the super light gas engines to choose from, so too late to go back now. There are so many light an powerful, reasonably priced gas engines out there now, that it's not even funny. I guess that's the price of procrastination.

Anyway, the new Evolution, BME, 3W55, Fuji EI, . . . etc. all look so promising for this airplane. Just remember, it has some evil tendencies and deserves respect on landing and takeoffs, but looks so pretty in the air with it's gentle roll and scale appearance.

Hope everyone has a Happy New Year!

JunkMan304

My Feedback: (3)

Thanks for all the help guys. I cant wait to get this plane finished. I beleive I will go with the gas engine I just dont know much about these smaller ones. I have mostly delt with DA 50's and such.

RCVFR

My Feedback: (7)

Really? Like what?

Chevalier

Bad Habits? I fly mine with an OS 120 III and have had no problems at all . My plane weighs in about 14lbs with 12 oz of lead in the nose. This is proof that the plan builds very, very tail heavy. If I were buildling another one, I would take all of the lumber out of the tail and rear of the fuselage. It takes off straighter than any other plane in my hanger and lands like a feather. In the air it does sweet looking snap rolls and spins. even flies some knife edge too.

beepee

Chevalier,

Nice job getting the weight as low as you have it. Mine came out at least a couple of pounds heavier and still has lead in the nose with the Quadra 42. This is not a kit design that can utilize the benefits of a very light engine. When I was putting mine together I was mounting a US41 on electronic ignition. It was SO tail heavy I switched over to the heavier Q42.

I think the Dynaflight SD flight characteristics are more myth than reality. There is enough washout in the wing to keep authority in the ailerons right down to stall. I get best landings with a little extra speed and throttle in a slightly shallow approach. Throttle back to idle after clearing the fence and just let it settle in. I can easily touch the tail first even with my over-weight condition. I have tried trainer like landings and found it will come in fine, but upon flairing the speed can be low enough that it will plop down hard. Ugly landing!

Have fun!

Bedford

RCVFR

My Feedback: (7)

Mine, with the G38 was a tad bit nose heavy - meaning when I tested for stall, it wouldn't. Stall, that is. At low throttle, full up elevator (at slow speed) it would just sort of mush forward, wings level, slowly losing altitude. Subsequent flight trimming called for some 4 or 5 ounces of lead on the aft hatch to balance out about right. It will stall, now, gently, no surprises. The aft balance also makes landings a bit slower and more comfortable. All up weight is just under 17 lbs.

I do like this plane.

Muhamed

Hi to All,

I'm a very beginner just ordered a whole combination of radio, plane kit, engine & everything form tower hobby. It's a Dynaflite Super decathelon with 6 channels radio. Is it hard to build for someone like me? is is hard to fly for me as well? thanks for replying & the advise.

AirmanBob

My Feedback: (14)

Mine came out at 18 pounds with a full size scale pilot and seats. I covered it with super-coverite and I'm using a US41 engine which gives it plenty of power. It balanced perfect with the servos in the rear. It flys in a scale like manner at about 3/4 throttle and landing are very easy. See my profile for a picture.

Bob

Rcpilot

My Feedback: (78)

Not the best choice for your first kit build.

I'd build a 4*60 or another kit first. The Dynaflite Decathlon is big and you really should have a couple kits under your belt before tackling this build.

Daryl_y

Muhamed welcome to the hobby/obseesion, If you are a true beginner you will probably have a hard time both building and flying the Decathlon, Since you say you are wanting to build I recomend the Sig LT-40 or 25 or one of the Great Planes PT series the Sig Kadet would also be a good choice it is built mostly with sticks which is more difficult to build than the others but would also give you more building practice and it is similar in size to the Decatholn. The LT's and the PT series trainers have much better instructions/plans and could be built in less than a 1/3 of the time as the Decathlon The main reasons why the Decatholn would not make a good trainer is that it does have a self righting ability like the other trainers also cost buy the time you buy a large motor (wheter gas or glow) high torque servos and 6+ rolls of covering you will be putting about $1000 dollars in the air. with one of those trainers mentioned above you will have less than $400 in the air. The Decathlon would make a pretty good second airplane I recomend building a trainer and make the Decatholn a 2nd airplane.

Muhamed

Daryl,

Thanks alot for the advise. The instructor at a nearby club told me the same & he said i will be putting a "pile of expensive stikcs on the ground soon" , i didnt know whether to cry or laugh, lol !! anyway, i will change the order to a trainer airplane. Thanks again