!Introduction

| spec2
| @903803
|> <b>Wingspan:</b> |< 70"
|> <b>Wing Area:</b> |< 862 sq. in.
|> <b>Weight:</b> |< 172 oz.
|> <b>Length:</b> |< 59"
|> <b>Wing Loading:</b> |< 28.7 oz/sq. ft.
|> <b>Servos:</b> |< (7) JR ST47 Standard
|> <b>Transmitter:</b> |< JR XF631
|> <b>Receiver:</b> |< JR RS600
|> <b>Battery:</b> |< Expert 2800
|> <b>Engine:</b> |< (2) Evolution .46NT
|> <b>Manufacturer:</b> |< <a href=http://www.horizonhobbies.com>www.horizonhobbies.com</a>
|> <b>Available From:</b> |< local hobby shops

The number of twin-engine ARF’s is growing, but mostly in the scale arena. There's been few offerings in the 'scale-ish' arena meant to help a modeler get into twins. Seagull Models have one ‘upped’ the most common "twinstar", with their even more scale version of a scale-like twin-engine sport plane. They call it the Dual Ace. The Ace sports a handsome 70” wingspan -- a two-piece wing so transportation is less of a headache as well.

In addition, the clear windows in the fuselage provide the modeler an option of adding a pilot and/or passenger(s), rendering this ‘sport’ model a very scale-like addition! Plus, the cockpit area is removable to enable access to the radio installation, and there is a lot of open space inside that cockpit for some detailing if you so desire. Interested? Keep reading if you are!

!Kit Contents
@903804:
@903816:Just some of the servos needed. These Sport servos functioned perfectly.

*What you will still need:
*(2) .40-.46 engines
*(1) Four channel radio (minimum)
*(2) 12” aileron extensions
*(3) “Y” connectors
*(2) Large aileron servo arms
*(7) Standard servos
*Fuel Tubing

!Assembly

Assembly of the Dual Ace is straightforward, well thought out, minimized in most places -- typical of the quality ARF's being offered ... with the only exception being the requirement of installing two of a few things -- engines, tanks, throttle servos, etc.

*Other than a few challenges (mentioned below), you don't get easier than this! Assembly sequence was as simple as installing...:
*hinges;
*aileron servos;
*engine box/engine/tank;
*engine nacelles;
*landing gears;
*tail feathers; and finally
*receiver/remaining radio installation.

The time required to proceed from opening the box to going to the flying site is probably about 10% longer than a normal single engine ARF. Of course some of us can convert a simple 10-minute job into an all day adventure, but that is just part of the fun when building a remote flying aircraft!

@903805:You will need a total of 7 servos for this one!

!!Wing

<div class = "leftside">
!CG Challenges & Solutions:

The CG recommended in the manual (80-90mm) is incorrect. The correct location should be 95mm-110mm back from the leading edge!

When the suggested location of the servos was tried, it was quickly apparent nose weight was needed. To reduce this amount, the servos were placed as far forward as possible. This presented some minor engineering challenges... longer pushrods were needed and the rudder pushrod had to be extended. Some copper wire and a scrap piece of wire solved that in a hurry. The rudder servo arm's screw prevented the cabin area from fully seating, so a portion of that crosspiece was removed.

The next challenge was the wing hold down bolts. The servos and pushrods now hampered access to this bolts, so the supplied bolts (which I felt were too long anyway) were replaced with DuBro's Hex head nylon bolts (P/N 142). An Expert 2800 mAh battery was installed in the fuse as far forward as possible. The reason for this selection was its weight. In spite of moving the servos forward and using the 'overkill' battery, 10.2 oz. of lead shot was still needed in the front of the fuselage (remember, I was trying to meet the misprinted CG!). The good news is that the final flying weight was still less than the recommended 11 pounds!

After a couple of flights some of the 'dead lead' was removed and the CG shifted closer to the 110mm area, and we found the plane handled much 'lighter' on the sticks and still did NOT have any snaping tendencies.

@903814:Using a balancer to guide my work, I repositioned the servos.

@903815:Some lead shot mixed with epoxy resulted in the CG at the 95mm location.

@903817:At this location the servos hamper, but do not prevent, access to the wing hold down bolts.

</div>


The two-piece wing made the assembly much easier than accomplishing the same feat with a large 70” one-piece wing.

The wing attachment bolts supplied were far too long and took a long time to thread so about 1” was removed. Due to the forward placement of the servos (my choice) hex head wing bolts were employed because of the reduced area. Apparently all the hardware is metric except the 1/4-20 wing bolts -- and it all works just fine!

Two of JR's Sport servos are now neatly hidden from view and drive the ailerons. Installation was quick and simple and large servo arms were required to clear the pushrod from the wing. Two (2) 12" extensions were needed to reach the wing root. Two additional servos were needed for throttle control and did not need any extensions.

@903806:Port side engine top view.
@903807:Port side engine bottom view.

Another plus for the Dual Ace occurred when the engine boxes were glued into position. Both boxes were very tight and aligned themselves perfectly without any modification on my part. The formers and servo location limited the tank size to I believe 8 oz.

These 'boxes' were epoxied in place and don't worry, due to the angle of the box and the slot in the wing it would be very difficult to glue the wrong one in place. The tanks and throttle servos were then installed for both engines. If you were paying close attention you now know why three (3) "Y" connectors were needed for the Dual Ace.

@903808:Tanks are relatively small, so watch your flight time.
@903809:Throttle servo installed.

I was afraid the fiberglass nacelles installation would be a challenge at first because I was worried about missing the ‘magic’ mark on the wing that was called for in the instructions. What mark? Was I to put a mark on the wing for the nacelle? Can't seem to find that instruction. Oh well, the bottom nacelle was then relieved of some fiberglass with my handy Dremel tool to clear the way for the engine and muffler. With the nacelle bottom tight against the leading edge of the wing, six screws were installed holding the nacelle firmly against the wing. That was simple!

Those six securing screws have very large heads and I felt it detracted from the great looks of the plane. So the supplied screws were used - but only on the bottom - and some more attractive socket head screws were used on the top and sides of the nacelle.

@903810:Almost a perfect fit. Note the screws holding the two halves together.
@903811:Nice combo!

With the bottom nacelle in position, a light plywood ring was installed to assist in securing the top nacelle. Then the fun began: installing the top fiberglass nacelle. It is designed to fit over the bottom nacelle and flush with the wing. That didn't happen - BUT by installing the spinner backplate and using that as the guide, I was able to force the top nacelle into position! The result was less than perfect but the author takes full responsibility for not getting a perfect match with the spinner. The engines were mounted 11 cm from the firewall and still resulted in a spinner/nacelle gap of about 4 mm.



With the two wing halves out of the way, attention turned toward the landing gear and tail feathers.
The main gear was a 'torque' style, held in place with the customary two nylon strips. The foam wheels were put on the axles after the bottom portion of the strut was flattened so the wheel collars would have a flat surface to be securely mounted.

The nose gear is also typical of most ARF's offered today. The nose gear block was already installed with wood screws. The control steering arm not only nicely fit the block but also lined up with the pre-installed pushrod housing. I have to admit, I have my doubts concerning the nosegear, both in strength and function. A very thin pushrod controls its movement and time will tell if the weight of the plane will cause any difficulty steering. I fly off asphalt so the wheels might have to be replaced. The 10" props clear the ground easily, but if you would like to use a 11" prop, larger wheels would be a must.

On the plus side, the Dual Ace really eases popular engine selection(s) -- any pair of .40-.46 will do this plane justice. Horizon was very generous in supplying two Evolution .46NT engines for our test model. Only a brief testing of the engines was needed before the Dual Ace was ready for its series of test flights. Both engines started from the very beginning by hand propping! No starter was ever needed.

!!Fuselage

Fiberglass nacelles, nose and tail cones arrived with the correct colors already painted to match the appropriate colorful scheme. The color scheme of our nose cone didn’t quite line up with the markings on the fuselage whereas the tail did.
@903812:Awaiting the radio installation.
@903813:Canopy sure needs some attention!

!!Tail
The tail feathers are approximately 3/32" thick sheet balsa. To remove the UltraCote, a Hot Knife was used to cut, err burn, through the covering.

!!Completion

Some of the trim needed to be reapplied, so a Trim Iron was used. Low heat was used after some high heat distorted one of the straight lines, oops! Overall the covering was reasonably bubble free.

When the wings and cockpit were added to the fuse, one beautiful looking twin filled our camera's lens. This is one bright colorful looking airplane. A lot of debate concerning what scale model I'd brought this time -- was it a Beechcraft, Piper or "who knows what" full-scale airplane -- was heard along the flight line.

!Flying

This bird is low-drag and easily flies relatively fast, as its streamline frontal area cuts through the air smoothly. With both engines running at full bore, it has nearly unlimited vertical (depending on prop selection). We found using a 10-6 prop produced much better results than the 11-5 we used orginally.
@929362
@929453

!!Taking Off and Landing

Takeoffs were easily accomplished as the Dual Ace broke ground at just less than full throttle, after advancing the throttle slowly. We had to be easy on the rudder as the nose gear was somewhat sensitive. Nonetheless, center line takeoffs were common as were the landings. Twice we landed with only one engine running and that did not present any problems. We like to keep the speed up 'just in case' one engine quits, but there have been times when we brought the plane in very slowly without any hint of snapping.
@929358
@929359

Twice we managed to break the nose gear - once was my fault (didn't flair enough) and the other was just too fast a landing. Either way, my fears were realized -- the nose gear needs reinforcement or better yet, a better quality unit.
@929361
@929365


!!Aerobatics/Special Flight Performance

Ah, the sound of a twin! Can't beat it (except maybe for 4 or more engines).

The Dual Ace rolls very true and required only a bit of compensating elevator to remain axial. Loops were as large as we would like.

Vertical climbs were uneventful, except when one engine decided to quit (on its first flight no less). By immediately throttling down to idle, a smooth glide was established and an uneventful landing ensued right at our feet.

Knife edge was difficult to maintain.

@929364
@929363

After a couple of flights some of the 'dead lead' was removed and the CG shifted closer to the 110mm area, and we found the plane handled much 'lighter' on the sticks and still did NOT have any snaping tendencies. I believe one of the reasons the nose gear was accidently made into a 'retract' was because of the noseheavyness during one of the first test flight...the Dual Ace just ran out of up elevator on a landing attempt. Because it is so easy to access the nose weight, I'd recommend starting at 100 mm back from the leading edge for the initial flight(s) and then continue to remove weight until it flys the way you like.

!!Is This For a Beginner?

This plane is not for a beginner - but it is easily recommended for a first time twin-engine aircraft by an experienced pilot.

!!Flight Video/Photo Gallery
+929344:The Dual Ace flies well, expecially at full throttle low level passes.


!Conclusion

*Hits:
*GREAT looks - is it scale? what model is it?
*Ease of flight, one engine or two
*Did I mention it looks great and flies even better?
*Easy, straightforward assembly with few difficult spots

*Misses:
*CG mistake in instructions
*The instruction manual's photos weren't the clearest, nor was the wording
*Covering had some minor bubbles
*Trim required very low heat to avoid melting/damage
*The fiberglassed engine nacelles were a challenge & needed some rework
*The nose gear requires additional support or replacement

If you want a head turner - check out the Dual Ace, and don't forget to 'finish' out the cockpit - this sure looks like a scale bird!

@929362

LOL
Check where leads "local hobby shops" link!

Great review Jerry! That video was really first class. There's nothing like the sound of a twin to get the blood pumping. The Dual Ace looks very "scale like" on the ground as well as in the air. Remember, it's not a bad thing to keep the crowd guessing as to exactly which real plane it may have been modeled after. I really like the idea of the removable wings. How difficult is it to remove and then reinstall the wing panels on the Dual Ace?

As for knife-edge flight with twins, the only success I've had was to use differential thrust mixed with the rudder channel. However, you have to be careful that you don't overtravel on the idle point for the slow engine and accidently kill it. Here's how I programmed it for my twin:

https://www.rcgroups.com/forums/showthread.php?t=489099

Mike McD

Wings are self contained, only have to connect the throttle and aileron leads and instert two bolts. The trouble is one side will fall as soon as the other wing panel is removed

How'd that link get in there???? HELP????

Originally Posted by Szymon Bartus

LOL
Check where leads "local hobby shops" link!

lol yeah someone needs to change that, i was at work when i clicked it :X hope no one was watching!!!

Could you make this plane a tail-dragger?? You'd get rid of a servo and the questionable nose gear. Just a thought.

oooooooo!!!!! I bet it woud look really cool too. Try it may be worth it. You could switch back to the 11 inch props.

Now wait. The CG would be off on the mains. So no it wouldn't work.

Hum,CG is off in the book.Thats why mine likes to land at about 50 MPH.Bet I change that.

I finished my new Dual Ace; very happy with that plane and indeed it is the club's attraction!!. I've also noticed that even with 40's engines it is overpowered. I started using 10x6 propellers and now I've changed to 10x5. This monday I will try this new configuration. I also installed on-board glow plugs which give me more confidence. Also I am expecting a couple of scale pilots to give a more realistic touch. Something that I did not install was the large DUAL ACE decal on the wings. This way everybody believes that this is a scale Piper Seneca.

Pictures to be posted later.

Really work on the cockpit area as it appears to be in a fishbowl! Pretty quick too

I have one of these and I'm thinking about using two Saito 56's. Do you think that will be enough power for normal flight?

Oh yes.....

you think the Evo 52's will be too much... I fly at 5000'msl
what about flaperons to help slow for landings??

Mile high eh? Yeah 52's will do you well and flaperons will help but watch out that you loose your aileron control when those are deployed. Stay on the rudder....