No Limits - Review of the Protech Unlimited

Bought as a second hand bargain, this untouched kit set me back half the normal price. Who could refuse? This article is a little late and I apologise but work and other social events kept me from the keys of scripture.

Electric powered aileron sailplane. Wing span: 63"(1.6M) Length: 40" (1.02M) Weight: 2.4 lb (1.1kg) approx. Having built the Topic 400 in less than the hour quoted and seen Choddy's Alpha 180 go together with equal ease, when I saw an advert for 'Untouched Kit ~ Protech Unlimited' ~ I could hardly wait for pay day. Choddy's 180 had also been flown with a aileron wing and he reported it flew very fast. I picked up the kit (complete with coat of dust on brand new box) and set about putting it all together whilst trying to better my 45 minutes on the Topic 400.

Pre-built fuselage with 540 motor & folding prop pre-fitted, pre-covered tail & wings, wiring for aileron servos pre installed, comprehensive instructions & the all important sticker set. Again I am impressed with the quality of the Protech ARTF kits. Components are secured in the box with dividers and each part wrapped individually in plastic bags.

JETI 35Amp speed controller. Hitec 5 ch. mini receiver. Two Protech mini servos. Two Futaba 148 std servos. Nimh - 3000mAh flight battery.

The tail is the first thing to be assembled and I recalled the problem I had with the Topic tail fin moving and splitting the wood around the locating pins. To this end I applied the modification suggested (be it too late by then) using servo mounting ferules to strengthen the holes while dispersing any abnormal loads more evenly.


Enlarge the holes slightly and gently press the ferules into the wood. This mod works very well and I would think any pin located surfaces would benefit from this adaptation. The next thing to go were the plastic clevices. Fuel tube is pushed over the metal clevice to prevent it popping open or rattling around too much.


Ensuring the tail is square is very important as any amount of play can cause it to be fitted crooked. The control horns are particularly nice and feature small nut shaped cutouts in the domes. The whole tail is bolted to the fuselage with the tail fin pins and secured with small nuts from below. Use threadlock or a small dab of cyno on the threads to prevent them coming undone.

Wing is joined with 2 alloy braces, pressed firmly together then secured using narrow fine weave glass tape then another strip of wider glass strand reinforced tape all the way round.

One criticism (about the only one too) I had with the Topic was that if the elevator up travel was set too far the pushrod could jam behind one of the cross braces in the fuselage behind the servos. To this end I fitted a small liteply shelf under the back of the servos and extended it past the beginning of the pushrod so it would have nothing to jam against.


On the unlimited this is even more of a problem, with part 1 in the picture jamming against point 2. It is very difficult to get the same shelf modification into place.


To counter this I turned the pushrods upside down and had the z-bends located to the servo arms from below. The bend in the pushrod wire at the servo end may need to be altered so it sits correctly at the sides of the servos throughout it's travel range. Set the servos to central when adjusting and ensure control surfaces are aligned correctly by using the clevices.

Gold bullet connectors are soldered to the motor wires to allow for the speed controller to be removed easily. 35Amp ESC used with BEC and Auto cut off. 5 channel receiver used to try out the twin ailerons as speed brakes or flaps at some point in the future. There is plenty of room inside the fuselage for a variety of speed controller/receiver/battery combinations. I chose a 7 cell, 8.4v, 3000mAh Nimh pack for added duration.

Servos fitted side by side in fuselage tray for rudder and elevator controls. Receiver wrapped in saver foam and fits just nicely in front of the servos with the aerial passed between them and out of the top of the fuselage behind the wing in a short antenna stalk made from a few inches of spare control snake inner.


Speed controller secured to front of battery frame with a quick release cable-tie with connector terminals positioned for easy battery connection. Cell pack fits snugly into the fuselage above the r/x and should be on the C of G to allow for minor adjustments. Canopy can be seen in place here as well as the new switch that had to be fitted to the ESC. (see Electra Fly in the Bumpy Graveyard for why this was needed)


The join of the fuselage and the body is perfect, no gaps anywhere. Wing is secured using 2 nylon bolts but provision has been made for dowel and band fixing if desired. Without the flight pack it is tail heavy and if the intention is to slope soar, it would require the r/x & r/x battery pack to be located quite far forward to balance correctly.

Very nice flyer. The C of G given in the instructions was a little tail heavy so I moved the flight pack forward during the next flight. The rolls are also a little slow even with full movement on the ailerons and it loses speed very quickly during a loop and does not always follow right over but drops out of the top. The stall is quite gentle but it does tend to tuck in if the nose is not kept up during a tight turn. With power off it will glide for quite a distance and comes in a lot faster than you might think. A stall at less then 10ft from the ground may result in an arrival nose first so keep the speed on until it wants to settle by itself and there should be no problems. This is not a beginners model, it is an ideal progression from the Topic-400 or Alpha-180. Although the assembly is very easy the flying requires it to be flown, it won't just float around by itself. It is also a very narrow airframe and it soon becomes hard to judge the orientation at a glance so keeping the model in sight at all times is a must. I also flew it without any stickers and being plain white it can soon get lost against a cloud. Bumpy Green Stripes are needed I think.

An easy model to build, instructions are quite clear and with a little common sense there should be no problems. It actually took me around 2 hours to complete this project, way over the 60 minutes quoted on the box. This was due to the soldering that needed to be done on the motor, ESC & servo extensions in the wings plus the mods I carried out. The mods I made are not critical to it flying, they are just my choice. Soldering is one thing I have had to learn to do properly and most people can get hold of a cheap soldering iron or at least know someone who knows how to use one. I would recommend this model to anyone with a bit of experience under their belt rather than a novice.

Article by Chinman from Bumpy Green Model Aerodrome
27th October 2001

Comment by Paul V on 00000000000000. Rating 5

Can anyone tell me what kind of duration they are getting from this model? I am umming and ahhing between the topic & the Unlimited, I have three planes under my belt (zagi, twinstar, cub), and want my first glider.

Comment by John on 00000000000000. Rating none

Hi Paul The duration for the Unlimited is variable, depending on the cell pack used and the amount of aerobatics performed over straight flight. I have no accurate timings but with an 8 cell 2400 it flies very well for around 8 - 10 minutes. With an 8 cell 3000 Nimh it is less potent but about 12 - 15 minutes is normal. With 10 cell 1700 it is ballistic for about 5 minutes. It is a very fast glider, not a soarer. For outright duration I would recomend then Topic 400 with 1300 or 1500 NiMh 8 cell packs. Alternatively the Java150 was flown by Grot with a 1500 pack on a breezy day for an hour. However the Topic & Java are not really able to do aerobatics, and are both 400 size soarers so a lot lighter.

Comment by martin on 00000000000000. Rating none

Hi,Can anyone tell me the C.G. for the unlimited please. Plus the canopy is missing, Protech e-address would be nice Thanks Martin P.S. Nice site, very imformative.

Comment by Daniel on 00000000000000. Rating none

Does anyone have a copy of the instructions for the protech unlimited 600 they can email me? I was given a second hande kit, all seems to be there but the instructions. Thanks Guys

Comment by Daniel on 00000000000000. Rating none

Don't worry, I found the Protech website & they have all the instructions available online in pdf format. here is the link http://www.protech.be/index.html

Comment by Terry Sullivan on 20040701193456. Rating 3

I have two freinds who fly the unlimited, and both have found it has the wrong name. With the standard motor, it is not very interesting. One has fitted a brushless 600, the other a gearbox. These mods both work very well. The guy who put in the gearbox has also fitted the speed brakes as suggested in the article, and finds these very useful.

Comment by Pete Moseley on 20050810225127. Rating 4

Recently put together a Protech Virage , which I understand is the same as the Unlimited but with a V tail...this, out of many planes I've had over the years, has proved to be the most troublesome to get to fly!!! I set the CofG as per the notes and in calm weather did power off hand launches - about 20metres and just flaring out at about 3foot up and every time it did a tip-stall flick to either left or right. No warps, ...then I spotted the likely culprit : the rounded wing tips in effect give a severly tappered wing at it's extremity and there is no noticable reduction in aerofoil thickness at this tip tapper point , so if you draw the angle of attack line from the mid leading edge to the trailing edge , then you can quickly see that the maintained thickness has the effect of increasing the angle of attack of the tips , so they can't help but stall furst ...so I cut them off!! and rebuilt almost square tips that reduced in aerofoil thickness over about the 10cms of the tip.. now we no longer had the flick tip stalls ....but now a gentle wingover - uncontrolable to nose in and crunch !!Why was the tail correcting this ? then I found out the fusalage is so flexable - especially side to side - that it would bend the tail assembly with any side force from the air stream so would not correct deviation from a straight flight path !! to prove this i temporarily tapped a length of carbon fibre tube to the outside rear section of the fusalage... a throw and bingo we have completely different flight characteristics - I now have control!! but now appears to feel a bit nose light and I've read someone else's comment that the c of g needs to be more forward that Protech say - i have yet to try this... but it's eventually getting to being flyable, at long last .. guess I'll have to find a way of putting and securing the rear fusalage carbon fibre stiffening inside the fus .

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