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Liftoff XS review

Allan Wright reviews the new Simprop Hotliner, the Liftoff XS. Imported by Hobby Lobby, this exciting little brother to the Liftoff offers a superb quality fiberglass fuselage kit and amazing flight performance.

Splash

Introduction


Wingspan:62”
Wing Area:341 sq. in.
Weight:40.7 oz as tested
Wing Loading:8.4 oz/sq. ft.
Servos:2 HS55 (ail), 1 HS85MG (el)
Transmitter:Hitec Eclipse 7
Receiver:Hitec Super8 Receiver
Battery:8-cell CP1700mAh SCR NiCd
Motor:AXI 2820/10
Prop:Aeronaut 12.5/9 folding
ESC:Jeti Advance 40-3P
Manufacturer:Simprop
Available From:Hobby Lobby

The Simprop Liftoff-XS is the next step in my ever-increasing 'need for speed' in electric R/C airplanes. My fastest previous model was the excellent Kwik-E by Gary Wright, which I overpowered with a Jeti brushless motor for some extra punch. The Liftoff-XS is a downsized version of the Simprop Liftoff and shows the distinctive lines of its larger brother. The airfoil is suitably thin to allow the Liftoff-XS to be considered as a proper hotliner if powered appropriately.

When Hobby Lobby announced that it was going to be carrying the Liftoff-XS, I was immediately interested in getting one of the first models available as I liked both the look of the model and its two-piece wing.

Kit Contents and Equipment

My kit came from Hobby Lobby with its usual high-quality packaging. Both wing halves came in a bubble-wrap wing bag with two separate compartments, a feature I'm planning to keep to protect the wing from damage when stored and transported. Hobby Lobby separately supplied all of the equipment needed to complete the airframe, including motor, ESC, servos, radio and accessories such as servo extensions, motor mount, etc; everything in their recommended set-up except the transmitter. (These items are not included in the regular kit but were provided so that this review would be complete using all of the manufacturer's recommended equipment.)

The Liftoff-XS's wing and stabilizer are sheeted foam and come precovered, with control surfaces installed and hinged. The wing's servo bays are precut and ready for servo installation. The wing covering on my Liftoff-XS was nicely done, even around the compound curves of the wingtips. There were a few spots that needed a pass of the iron to smooth areas where the covering had relaxed, but these were quickly and easily fixed.

The fuselage is gel-coated fiberglass, including the fixed rudder. A carbon fiber canopy and extensive graphics also are included. Finish of the carbon and fiberglass parts was also excellent, and the canopy on my plane fit perfectly.

I was excited to get started on the plane. The power system provided by Hobby Lobby included a Model Motors AXI 2820/10 outrunner brushless motor, Jeti 'Advance' ESC, an 8-cell CP-1700 mAh SCR Nicad battery pack and an Aeronaut 12.5/9" Folding propeller. There also were additional laser-cut plywood motor mounting plates in the kit's accessory pack.

Two HS-55 for the ailerons and one Hitec HS-85MG servo for the elevator were provided for control, along with several servo extensions and a Hitec Super-8 receiver. I was pleased to see a metal geared servo on the elevator of such a fast airplane. I expected the elevator servo to see some stress at high speeds. Since the Liftoff-XS has a two-servo wing, I chose to use my Hitec Eclipse-7 transmitter so I could use flaperon/spoileron functions during landings.

Assembly

Electronics and Propeller

At the time of arrival of the Liftoff-XS, we had two feet of snow here in New Hampshire – not ideal conditions. Anxious to get out as soon as possible, I did what I could by preparing the electronics first.

The AXI motor came with 3.5mm bullet terminals preconnected, but I had to solder the mating connectors to the ESC as well as adding Deans Ultra connectors to the battery and ESC. One thing I like to do is to add additional strain relief to the wiring attached to the Deans connectors. I do this by adding a layer of shrink wrap over the entire connector and wires. This prevents accidentally pulling a wire or shrink wrap off the wire when disconnecting the battery. Some of the better battery pack manufacturers do this, which I now replicate on my own packs and ESCs. Sometimes taking care of details allows you to spend more time at the flying field in the air and not on your tailgate making repairs.

I didn’t need to use my building board to assemble the Aeronaut folding prop. The part fit is excellent, and I liked the way the locking nuts held on the folding blades, allowing me to adjust the tension on the pivot for free-folding movement without any extra slop. The carbon-filled blades needed sanding to remove mold lines and balance them on the yoke, but once this was done, the final product was well worth the time. To balance the blades on the yoke I tightened the locking nuts so the blades wouldn't fold. The yoke fit my prop balancer like a conventional prop. Once the prop was balanced, I loosened the locking nuts to allow the blades to fold easily and installed the yoke onto the spinner and collet. Total assembly time for the electronics and propeller was about an hour including taking photographs and notes for this review.

Airframe

The instructions for the Liftoff-XS come in two parts: the original instructions from the manufacturer with diagrams, but with German text, and an English instruction sheet containing text only. There was plenty of information to keep me on track, although on some steps the translation was confusing reading. Since hotliners aren't beginners models, I'm sure others also will also be able to work their way through the assembly steps without much difficulty, but a complete English translation with images would've been nice to have.

Wings

The wings come completed and covered so all that needs to be done to it is to reinforce the aileron hinges with the provided hinge tape and to install the HS-55 servos. I prefer to remove the mounting lugs on my wing-mounted servos and cover them with shrink tubing so I can glue them in place, but still be able to remove them later by cutting the tubing. Since I was out of clear shrink tubing, I had to use the ugly orange tubing seen in the photo. Simprop includes some interesting adhesive strips in the kit to attach the servos, but I chose to stick with my method.

I've had trouble with servo extensions when I remove the connectors to run the extension through the wing, so I simply cut the extension, installed it in the wing, and soldered the wires back together. This prevents the connector's terminals from getting damaged, and I've yet to have a problem doing it this way.

I installed the supplied aileron control horns with epoxy to prevent damage to the aileron's foam core. The provided pushrod hardware is a single clevis and a threaded pushrod, which gets a Z-bend. Since the linkage was short, I used Sullivan 6-32 threaded rod and a second clevis to make the pushrod. This made a nice secure, slop-free, adjustable connection. Notice the fuel tubing used to secure each plastic clevis. This is another case of taking care of the details to prevent a possible failure later. On park-flyers, this step isn't always necessary, but on a fast plane like the Liftoff-XS, I consider it mandatory. I chose to tape on the servo covers instead of gluing them on, as the instructions indicated, in case I needed to remove them.

Fuselage

With the wing assembly completed, I installed the mounting hardware into the fuselage decking. First I reinforced the underside of the decking by gluing in the plywood reinforcement with epoxy. Once the epoxy had hardened I temporarily mounted the wing, marked the hole locations, drilled the holes and installed the provided T-nuts to accept the nylon wing bolts.

I mounted the wing onto the fuselage and began working on the carbon-fiber canopy. My cover fit perfectly as shipped. A piano retaining wire is used to secure the canopy in flight. This is a tried and true method used in a lot of sailplanes, and it works particularly well on the XS since the fuselage has a recessed groove for the canopy...Once I bent the wire so that it worked appropriately, I epoxied it to the canopy with five-minute epoxy using the provided plywood blocks for support. For the rear end of the clip, I used a small needle file to shape a 'V' groove into the underside of the lip in the fuselage. For the front side I drilled a simple hole into the fuselage.

Two items also shown well in the photos above are the cooling holes in the nose of the plane and the plywood front battery mount. The cooling holes come premolded in the nose of the plane as 1/8" indentations in the fiberglass molding. The holes are made by carefully cutting out these indentations. I did this with hand tools using an X-Acto knife for the initial cutting, followed by needle files and a sanding stick. More aggressive or skilled modelers could use a Dremel tool, but I wanted to be cautious to insure a nice looking hole. The parts for the front battery mount came precut so I assembled them and glued them into the fuselage with epoxy once I roughed up the inside of the fuselage with sandpaper and cleaned it with acetone to remove mold release agents.

The next step was the motor mount. This was the only part of the build where I needed to improvise to achieve a perfect result. Hobby Lobby provided some nice laser-cut motor mounts with the accessory package, and I used those to mark the front of the fuselage for the motor mount. The instructions call for gluing the provided plywood motor mount inside the fuselage with epoxy, after making sure the inside mold line is sanded smooth. With all of the tools available to me, I was unable to get anything into the nose of the plane to do this, so instead I mixed up some epoxy with micro-balloons and glued the plywood motor mount into the fuselage, allowing the micro-balloon-filled epoxy to fill any gaps between the mount and the nose of the plane. After this had set, I put some additional full-strength epoxy behind the mount to insure a strong joint.

Once the epoxy hardened, I drilled the motor mount and cooling holes and refined the mount using some round needle files. I used all four mounting screws on the motor to insure a secure mount. When I first mounted the prop onto the motor, I found that the aeronaut prop hub made the propeller stand away from the fuselage a good 1/4-inch, making the gap from the spinner to the fuselage unacceptably large for my tastes. To remedy this I enlarged the center hole in the motor mount to allow the hub to sit inside the fuselage 1/4-inch and used one of the laser-cut motor mounts provided by Hobby Lobby as a spacer inside the fuselage. With this slight modification, the fit of the spinner and folding propeller was perfect.

The rudder of the Liftoff-XS is integral to the fuselage and has a slot molded into it to accept the horizontal stabilizer. Before I attached the stabilizer, I mounted the control horn on the pre-attached elevator since it is much easier than after the stabilizer is mounted. I also used my Dremel tool to cut out the servo opening and pushrod exit on the rear of the fuselage. Once I test fitted the stabilizer and was sure it was aligned properly, I marked the covering and removed the portion at the glue joint. I used five-minute epoxy for the joint.

I used more orange shrink wrap on the elevator servo, and after several test fittings I was able to get the pushrod bent to a shape that moved the elevator without any binding. I marked the shrink wrap with permanent marker so when I epoxied it in I could locate it easily. The decal sheet contained a cover for the opening that shrunk nice and tight with a covering iron after it was applied.

The last part of the assembly is locating all of the equipment in the fuselage. I found it easiest to mount the receiver in the rear of the fuselage under the wing mount. I prefer to use short 6-inch extensions on my receiver for wing-mounted servos. Having them makes hooking up the wing servos much easier at the field. It's important to mark the extensions so you can tell which one is the right and left. I use white electrical tape on the right servo extensions.

In front of the receiver is the battery mount, which I added a Velcro 'seat belt' to insure a solid hold on the battery during high-G maneuvers and inverted flight. The Jeti Advance ESC has an arming switch which I mounted under the canopy on a small balsa block. The ESC is attached to the fuselage bottom with Velcro. I secured the power leads from the motor to the ESC against the side of the fuselage with fiberglass strapping tape to make sure that they didn't accidentally rub against the rotating can of the AXI motor. Finally I marked the CG range on the wing saddle so when I change batteries I can double-check that the plane is balanced.

The Liftoff-XS comes with a generous sheet of adhesive-backed decals to decorate your plane in full livery. Some of these markings are quite large so I used some window cleaner on the surface first and 'floated' the decals into position. Once I was happy with their location, I used a damp towel to squeegee most of the cleaner out from under the decals. After drying overnight they were fully dried. The main wing decal was applied in one piece, then cut afterward. This gave me a nice clean split with both halves perfectly aligned.

CG Balance and Radio Setup

I found that with the equipment located where I installed it, I could easily adjust the CG throughout the full recommended range by simply moving the battery forward and backward on the Velcro. No additional nose or tail weight was necessary. I set my radio up to allow the ailerons to be used as flaperons on landing with 10% down elevator mixed to the flaps to prevent the nose from ballooning when the flaps were deployed. I also programmed the ailerons to have only 50% travel when below the wing, and 100% above to help reduce adverse yaw in aggressive turns. Finally I programmed in some mild exponential on both the ailerons and elevator to allow me to do gentle sailplane maneuvers while gliding while still having the ability to fly aggressive aerobatics while under power.

Flying

Much to my dismay, it took a good six weeks for the weather here in New Hampshire to improve to the point where I could attempt a maiden flight of the Liftoff-XS. Once the snow melted and the spring rains passed, I headed out to a large 100+ acre hayfield. I wanted plenty of room on the first flights with such a fast plane. My friend Robert Anderson accompanied me as photographer. Please forgive the graininess of some of the photos; photographing such a fast plane with a digital camera proved to be very difficult.

The climb out with the recommended AXI outrunner is very good. With just a couple seconds of level flight to allow the prop to get 'on step', the liftoff can climb out at well over 45 degrees, in fact very close to vertical. From full-speed level flight vertical climbs carry momentum at least 500 feet. Power-on level flight was much faster than my Kwik-E, which has been estimated to be at least 60 mph, so my estimate is that the Liftoff-XS is over 70 mph. Dive speeds are blisteringly fast, in fact the slick profile of the fuselage and wing actually make power-off dives with the prop folded faster than power-on dives.

The liftoff will do giant loops from level flight, and rolls can be nice and axial with some slight correction with the elevator while inverted, as seen on the video.

Downloads

When slowing down for power-off approaches, the plane doesn't seem to favor either wingtip in a stall, but the altitude loss during a stall is abrupt. By applying the ailerons as flaps or flaperons, this is prevented and landing approaches are much less 'tricky'. I found it necessary to mix about 8% elevator with my flaps to have the plane maintain a level glide instead of ballooning. On one of my landings on this session I caught a wingtip on an uneven clump of hay and stripped one of the aileron servos. There was no other damage to the wing as it appears to be strong enough to take the occasional rough landing at speed. I'm sure this wouldn't have happened on a proper R/C landing strip, even a grass one, but it did on my farm field.

At home, I realized I didn't have a replacement HS-55, so I chose to replace both wing servos to insure that they remained matched. I used a pair of HS-81 servos as replacements. The HS-81 servos fit comfortably in the pre-cut servo bays and the plastic servo covers also fit the larger servos with ease. An additional benefit to the larger servos was that I was able to get more deflection when using the ailerons in flap mode.

Since replacing the wing servos, I've had several more flying sessions with the Liftoff-XS. A recent flying session yielded the video used in this article, which was taken by my wife, Lori. I've found the Liftoff-XS to fly predictably both under power and while gliding, but I also continue to find the high speed of the Liftoff-XS challenging.

Conclusion

The Liftoff-XS is a high-quality high-speed electric powered glider that well deserves its label as a 'hotliner'. It was an exceptional quality kit and easy to assemble. Both the airframe and the recommended equipment provided by Hobby Lobby perform as advertised and exceeded my expectations. This is a plane that will excite and challenge experienced pilots with a 'need for speed' and a flying area large enough to accommodate a very fast plane.

Last edited by jbourke; Apr 26, 2004 at 09:23 PM..

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Old Apr 26, 2004, 04:46 PM
Mebbe I'll fly this year??
Speed E Freak's Avatar
Colne, Lancs, ENGLAND, UK
Joined Aug 2002
1,092 Posts
Great Review!
I'm just in the market for something along these lines. I was looking at either this or the bandit. Both have axi 2820/10 recommended. I did have one of these, but i sold it on. I do however have a hacker C40 12S awaiting a plane.
Could be possible, i've got 10x1700cp's or 10x1950 faups that should fit.
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Old Apr 26, 2004, 06:40 PM
Gambler-AG DLG Designer
Allan Wright's Avatar
Lee, NH, USA
Joined Jun 2001
5,187 Posts
My 1700s are shown in the article photo, if your packs are that type (side by side) then the 1950s should fit fine. I've never seen a Bandit fly, but I can tell you this thing is FAAAAAST. Landing with flapperons isn't too bad, no tip stall, which I hear is
a bugger with the Bandit.
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Old Apr 26, 2004, 06:47 PM
BANNED!!!
soholingo's Avatar
Laurel, MD
Joined May 2001
12,687 Posts
I think selling the simprop with an axi is doing this plane a disservice. Its a good motor for a beginning hotliner pilot but if you are going to really wring it out, put a stronger motor in it. I have one, and I am going to put either a hacker fai f5f 5l or a plettenburg 7 cell setup. (I may even cut flaps into the wing). I don't understand why hs55's were used for wings, VERY weak servos for a plane with these capabilities. Lastly, there are better cells than the cp1700.

I know this setup was done with HL materials in mind, but I don't think it will show the real potential of this setup until they use the latest components.

jay
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Old Apr 27, 2004, 12:20 AM
Mebbe I'll fly this year??
Speed E Freak's Avatar
Colne, Lancs, ENGLAND, UK
Joined Aug 2002
1,092 Posts
I'll be new to this hotliner game. Flown plenty of small fast brushless planes, and a few moulded gliders, but not merged the two.
Anyone think the C40 will be of any use? Recommended gear ratio and prop size for 10 cells?
Thanks
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Old Apr 27, 2004, 12:58 AM
Registered User
Singapore
Joined Jul 2003
643 Posts
Allan,
Thx for the review. I've been there and done that and agree completely with you that despite the speed the LO likes, it has no bad tip stalling habits. I think however that a larger prop can be used - I prefer a 14x9.5 or 13x11. Amp draw would be around 45A with 8 CP1700s.

Also, I'm grateful that you swapped out the HS55 servos - that spells diseaster to me. I bet you haven't tried a roll after a 1000ft vertical dive yet? The aileron squeal can be deafening... I can imagine that amount of force the servos have to put up with...

Now for a Hacker B40-6L power setup to get a taste of F5B...
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Old Apr 29, 2004, 04:42 AM
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mattg's Avatar
Sydney, Australia
Joined Feb 2003
486 Posts
Flapperons

Hi Allan,
I'm keen to know why you chose to go with flapperons as opposed to spoilerons. Am I right in assuming the ailerons account for roughly the outer half of each panel?

Will be keen to hear how this plane handles a bit more abuse, especially given it's sold in Europe as a one piece wing. Please let us know through the thread as time goes by.

Thanks for the review, the kit looks very impressive in terms of it's completeness, have fun.

Matt.
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Old Apr 29, 2004, 06:50 AM
Mebbe I'll fly this year??
Speed E Freak's Avatar
Colne, Lancs, ENGLAND, UK
Joined Aug 2002
1,092 Posts
Quote:
Originally Posted by mattg
Will be keen to hear how this plane handles a bit more abuse, especially given it's sold in Europe as a one piece wing. Please let us know through the thread as time goes by.



Matt.
That's an interesting point. I've ordered one, and it says on j perkins (uk distributors) website that it is a one piece wing. This is the kit version though, I don't think they import the artf version. Hopefully it'll be able to take a bit of hammer!
It's looking like i'll have to make do with either the C40 i've got, or buy an AXI 2820/10. Should climb well enough with either (i hope!)
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Old Apr 29, 2004, 08:08 AM
Gambler-AG DLG Designer
Allan Wright's Avatar
Lee, NH, USA
Joined Jun 2001
5,187 Posts
The wing joiner on my 2-piece wing is a 3/8" diameter steel rod, and the in-wing tubes are brass, so I don't think I'm going to have too many problems with the wing strength. I've done some agressive loops and pull-outs from screeming dives and so far no problems.

The HS-81 servos for me are a much better choice for the wings. Nice and strong.

I chose flaperons, because I've used them before, plus they seem to keep the wingtips from stalling so I get a nice predictable 'mush' on landing.

I'll try using a larger prop as suggested. I understand Sholingo's need for additional speed, but for now the AXI is still giving me plenty of adrenaline when flying. This plane is a HUGE step up in speed from my Kwik-E
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Old Apr 29, 2004, 09:12 AM
Mebbe I'll fly this year??
Speed E Freak's Avatar
Colne, Lancs, ENGLAND, UK
Joined Aug 2002
1,092 Posts
Allan,
I've been using the HS81's for a few years now. probably had about 16 of them altogether. I have had about 5 of them with potentiometers that have gone duff though, and one that just died a sudden death mid flight. Maybe i'm just unlucky - has anyone else had issues with them?
I'm certainly looking at a metal geared servo on the elevator at least. If you loose one aileron you can still land. Loose the elevator, and it's goodnight vienna!
Any recommendations?
On the flapperon / spoileron discussion, is spoilerons both up, and flapperons both down? Any reasoning behind one rather that the other?
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Old Apr 29, 2004, 10:34 AM
Registered User
Singapore
Joined Jul 2003
643 Posts
Allan,
Actually a 13x11 or 14x9.5 prop will not give a significant increase in speed - but it will give a much better climb in my experience.

I use the JR/Graupner DS368 on the elevator - sits perfectly in the cutout and is super precise. I used spoilerons (ailerons up) for landing with down elevator compensation. The spoilerons do not really slow the XS down very much but they prevent the speed demon from accelerating again when down elevator is applied to bring the plane down.

Also, the find the 2-piece wing (with that steel joiner and brass tubes) strong enough for any manoveur in the air.

Rgds.
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Old Apr 29, 2004, 01:00 PM
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Neil Stainton's Avatar
United Kingdom, England, Stratford-upon-Avon
Joined Feb 2001
3,906 Posts
Nice review, but I think the wing loading is wrong:
<<
Wingspan: 62”
Wing Area: 341 sq. in.
Weight: 40.7 oz as tested
Wing Loading: 8.4 oz/sq. ft
>>
I calculate it as 17.2oz per square foot!

Neil.
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Old May 06, 2004, 09:25 AM
Registered User
Hervey Bay, Sunny Qld, Australia
Joined Jun 2001
1,773 Posts
The figures must be mis-printed. Neil IS right. 40.7oz / 2.36ft2=17.2oz/ft. No wonder the Simprop XS is a screamer. 17.2oz should be fine though I guess. Are the figures mis-printed Allan?
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Old May 21, 2004, 02:24 PM
Gambler-AG DLG Designer
Allan Wright's Avatar
Lee, NH, USA
Joined Jun 2001
5,187 Posts
Figures are correct, my math is wrong. 17.2 is correct. Still with the flaps deployed ti does slow down fairly well. In the air it's a screamer though. The best part is hearing the wind whistle over the wings in a death dive. Energy retention seems to be great at all speeds.
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