Nigel Heather

This seems to be a better listing. You can select ARF and PNP, different prices and it has a table showing the difference. You can also choose between the two different colours. https://iactiverc.com/products/omphobby-challenger-49-balsa-airplane?variant=41837155516568 Personally I think the Sussex Model Centre listing is wrong.

There’s this natural human nature to think you can save the plane. Decades ago, in my IC days I built a lovely ARFT Chipmunk. I took off and it was immediately apparent that it was very tail heavy. What I should have done is as soon as it lifted off was put it down, low altitude, lowish speed, yes there would have been damage but it would have be repairable. But natural survival instinct kicked in, I was determined to save it. As it bucked and looped, it gained altitude, totally uncontrollable, until it eventually won and went it the ground from a much higher height and much faster - bin bag full of match sticks and firewood. In the video, the guy with the B25 did similar, he should have accepted the heavy landing but he fought to save it, aborted the landing, went round again and end up digging a hole in the mountain with a vertical dive into the ground.

So it does, and that is my nearest RC Hobby store. But that leaves me puzzled about the difference between the ARF/ARFT and PNP versions. This is the PNP version https://www.hely-shop.co.uk/omphobby-challenger-49-balsa-airplane-electric-green-pnp/ Traditionally, ARF/ARTF has meant the airframe is pre-built and covered, just needs minor assembly and installation of electronics of your choice. But here, OMP have ARF/ARTF and PNP versions which appear to be identical (apart from colour scheme) but have a £70 price difference.

Always envious of these Americans with their flat tarmac runways. Cheers, Nigel

Yep definitely good advice - I would do that if I bought another - unfortunately, like many, I only came across that sage wisdom after the event. The other thing I’d recommend is to fit bigger wheels. Slightly spoils the lines but the stock wheels are tiny so dig into divots and the longer grass at the edge of the strip. What happened to me, a few flights in, coming in nice and slow, looked like it was going to be a really gentle landing but misjudged the descent and just clipped the very edge of the strip on touch down. The strip is mown short, the grass around is unmown but short because we share our field with sheep - so an inch or so - but that was too much, I was shocked, such a slow landing but those tiny wheels just grabbed onto the short grass and ripped the undercarriage from the fuselage.

Where is it £180, seems to be landing around the £250 in my search. That’s for the PNP version including motor, esc and servos. There is an ARTF version for £180, not entirely clear what you don’t get but I assume all the electronics. That being said, £250 is still a good price - if I’d seen this earlier this year I would have bought one instead of what I decided to go with (Ruckus). What I particularly like is the well thought out installation - this is where the battery goes, this is where the receiver goes. Really like that. Currently fighting with how to install ESC, battery and receiver in a Ruckus - they all go into the same space complete with protruding undercarriage and wind bolts (battery puncture risk). Feel like I’m going to have to build some extra structure like others have done. With receivers often having built-in 3-axis gyros gone are the days where you can just push them in anywhere and not bother about orientation. So top marks for OMP for actually thinking about the installation.

Not quite - the price includes a standard connector - it has been Deans for all the ones that I have looked at but maybe that changes for bigger batteries. The +£1 is if you want a different connector. So for the batteries I was looking at, Deans was included in the price but EC3 or XT60 were £1 extra. BTW I quite like Deans although I have started to standardise o XT60. Still use Deans on my AcroWot foam-E because the Deans are much smaller and the battery compartment is very cramped.

Thanks for the suggestion. Mine isn’t marked as a Quantum 40, it has Century branding. I tried the instructions anyway but they didn’t do anything. I must admit, I don’t recall ever having to set anything up, it just worked. Cheers, Nigel

Does anyone know if the ESCs that come with the Wot foamies (Wot4, AcoWot, Wots Wot) are configurable - in particular do you have to 'tell' it the full and zero throttle. I've looked through the instructions and can't see anything. I can understand why the configuration could be hard set (non-configurable) but I would have thought you would have to teach it the full and zero throttle position.

Usually with ESCs, you have to, as a minimum, tell it the full and zero throttle stick positions. Additionally, most ESCs are programmable, either by using a programming card or through a series of beeps and throttle stick positions - this can be used to set things like brake, timing, BEC voltage, LiPo voltage protection. As far as I can see, you can't do any of this with the Wot ESCs. To be honest I get that for the configuration, as they know the model they can hard-set the configuration but I would have thought you would still need to tell it the full and zero throttle.

I've never tried the 'glue-fix' myself just read that others had done it. So I'm speculating to a degree - the reason I'm not so sure about epoxy is that it is quite brittle. The nature of the foam is that it will flex and I'm thinking that when it does the epoxy will crack or detach. So if I were doing it I'd use UHU POR which it quite tough, grips foam very well, but is also slightly flexible too. It is the best glue I have found for foam repairs so at some point you are probably want to get a tube.

Question about the ESC - do you have to have to set the max and min on it - you usually have to tell an ESC what is full throttle but can't see anything in the Acrowot instructions. I ask because I'm not convinced my motor is running at full speed.

And the undercarriage mount.

Apologies, I'm a bit behind with this thread so have missed a few questions I don't know whether adding a flexible glue to the motor mount where it slots into the foam will help or not, I have read that it does but I have never tried it myself. The reason I think it would be best added when new rather than when it gets loose is that you are fixing it at the correct thrust angle. Once it becomes loose you can move the motor around a little so how do you know what angle to fix it at. The model comes with the motor preinstalled but it can be removed and replaced afterwards - it's a little fiddly, but undo the four screws on the front attaching the motor to the mount and then ease the motor through the battery hatch. You may have the cut the zip-tie fixing the leads to the mount. The engine mount is a different matter, this is installed at the factory when the fuselage is in two halves. Once you receive it there is no way of replacing it. This is different to the Wot4 which can be replaced. If you look at the list of Wot spares there is a Wot4 mount but no Acrowot mount - this is because it is impossible to remove or replace. The undercarriage mount is a similar story to motor mount. It is installed during factory assembly and there is no way to replace it when it (inevitably) snaps off - once that happens you need to come up with a home-made DIY fix - or, as Ripmax would prefer, buy a replacement fuselage (if they ever have them in stock).

Yes I've seen them before, don't think they look as nice as the Cambrian Fun Fighters.

As I said in my previous post, it is possible. At the front you can see the 25mm circular hole that the motor shaft will poke through. Already installed in the fuselage is a metal mount which is a square U-shaped metal bracket - the flat end points toward the hole at the front and the two arms point backwards and have ears that jam into slots in the fuselage sides. The motor mount can only be fitted during assembly at the factory. Underneath in the nose is the battery compartment, you can see the hatch for it in the picture. To install the motor you must first ensure that the prop adapter is not fitted and then you thread the motor up through the battery hatch and wriggle it into position so that the shaft pokes through the hole at the front. You can then secure the motor to the bracket using four screws made out of Chinesium - this ensures that when they have been tightened up the screw heads will be so deformed that anyone wanting to remove them will have a tough job. Once the motor is in place you can install and tighten the prop adapter - this partially obscures the screw heads making them impossible/difficult to access without first removing the prop adapter. Yes if I had another, the first thing I would be inclined to do would be to remove the motor and then apply UHU POR, or silicone sealant to the area where the metal mount slots into the foam. Access is poor but should be possible using a combination of through the motor and vent holes in the front and through the battery compartment. When refitting the motor I would throw the screws in the bin and replace with some decent ones.

I have seen several mentions that the Cambrian Fun Fighters are a bit porky and land fast. Are there any alternatives that you could recommend. The Cambrian Fun Fighters do appeal because of the price and the range of models offered but always interested to hear other suggestions. Also of the Cambrian Fun Fighters, do any stand out as flying better?

Unfortunately not. There are a lot of things I like about the Acrowot Foam-E, but the motor mount is not one of them. There is no cowling, the motor mount is encased in the two halves of the foam fuselage wedged into slots - this is the cause of many complaints as the plane gets older because as the foam compresses, stretches and flexes the mount become more loose and the thrust angle starts to drift around. But back to the motor - the prop adaptor and the motor mounting screws are accessed through a 25mm circular hole in the front of the fuselage behind the spinner. Through this hole you can see four screws made of Chinesium, and using your skills gained through years as a practicing gynaecologist you can undo these screws and then coax the motor down through the small battery hatch. The kicker is to be able to loosen those screws you need to remove the prop adapter first as it is blocking access to them. In this case there were only two options - a puller, though I'm not convinced that you could get the claws through the 25mm hole and behind the collet, also the threaded shaft is aluminium and quite long so there is every chance that it will bend - or dremel it off and buy a replacement. I did the latter.

It’s bit moot in my case now as I have dremel’ed the prop adapter off. But I don’t think a blowtorch would work, no matter how tiny, the foam is just to close and would melt.

Fancy doing a fun fighter warbird, so a belly lander, but have a question about the propellor. With IC powered planes you can fit the propellor relative to the compression so that the prop will stop horizontal, but as far as I am aware, even if you can stop an electric motor (unlike a cut IC motor a stopped electric motor will still free-wheel), it could stop in any orientation. So what is to stop an electric powered belly lander from breaking a prop every few flights. Do you have to go with a folding prop or is there another way, or is it that this isn’t even a problem.

No I didn't know that. I had just been looking at my locals shop that sells lots of different sizes but not an assorted pack - so you need to know what size to buy. What I'm sure about is how much tension - the balance of tension and not crishing the wing.

No that’s how it works on the Ruckus. The Wot4 has a plastic cowling that comes off and gives good access. But with the AcroWot the motor is essentially encased in foam. Decided to dremel it off and buy a new prop adaptor.

Any tips on how to remove a collet type prop adapter - it’s on very tight. I tried pulling the cone with pliers but it is on there too tight. It’s in a AcroWot foam-e so access is very limited and I can’t use heat. I looked up commercial pullers and apart from the expense, I doubt they would be able to get in behind the cone because access is so limited. Plan is to make something but before I go to that effort thought I’d check here to see if there clever ideas.

Have a plane to build that uses wing bands. Haven't used wing bands for decades and then they came with the kit. This time I have to buy them - is there a good rule of thumb of what length to buy - obviously shorter than the distance over the wing between the dowels but how much by?

I wonder whether normal aliphatic mixed with acrylic thinners would make a SuperPhatic like glue? Cheers, Nigel