Martin

I would assume from Evolution Models. Their website seems to be a work in progress and doesn't show it, but it does have a "sales" email address.

http://evolution-models.com/

sales@evolution-models.com

Personally, I am quite interested in the glider that James was talking about.

What was the problem?

Please can you update my permissions so that I can edit the origional post of this tread.

I can't edit user permissions, but I can edit posts, so I've done that as the next best thing. Can you please check it to see that I've done it correctly. I'm not sure why you can't edit the post - I thought all users could edit their own posts.

I have a backup of the old website CMS database that I took on 28th February last year.

I checked, and the SMAS article does appear in the backup. I've managed to extract the article text and HTML formatting, have fixed some punctuation that got broken in the process, and I have this in a file on my computer. I can email it to you or anyone else, but I don't have access to the new website to put it back.

funflyjames said:

Last time I looked the Irvine 39 was about £80, but most places are out of stock. I think Ripmax must have a stock of them to get rid of which is why they are selling them with the Wot 4.

Is it the 39 or the 36 that they're selling with the WOT4? When the guy from Ripmax gave a talk at a club night a couple of years ago he gave the impression that they had loads of Irvine 36s, which is why at that time they were doing a giveaway bundle price for the engine with their Jive funfly ARTF. I think these were still the UK-manufactured 36s, too.

I know that it says 39 on those pages, but I just wonder if wires have got crossed somewhere. Or maybe the "39 Special Edition" is some modification of a 36!

As far as I'm aware, the 39 and 53 are both pretty much impossible to get other than second-hand, and even there people hang on to them. The odd unused one might pop up from time to time, but that's it. Certainly when the Ripmax guy was asked about the 53 he said that Ripmax have no stock and none were being manufactured as they hadn't worked out a way to do so cost-effectively. The last generation of the 46 and 53 had been manufactured by O.S., but that deal had finished.

Martin

ChasePlane said:

If it is 66A shouldn't the esc be rated higher?

No - this just means the pack is capable of supplying 66A if called upon to do so. Generally people will allow a bit of a safety margin when specifying ESCs and batteries.

From the motor specification at https://www.emaxmodel.com/gt2826.html , the motor is quoted as drawing 51A off a 4S pack with a 14x7 APC prop, so around 60A capability for ESC and pack seems fair.

Generally, people will select the pack capacity based on size and weight once the number of cells is chosen. The required C rating then comes from the motor's rated maximum current draw divided by the pack capacity - in this case 51A divided by 3.3mAh which is about 15.5C, but to allow a bit of headroom and because no-one makes batteries under about 20C they specify 20C. The required C rating is only ever a minimum requirement - anything higher will be fine though usually more expensive.

What does the recovery do? I assume return to vertical, but does it return to a static hover or just to a state where the only acceleration is 9.8m/s/s downwards? (That would require the ability to detect velocity/position rather than just acceleration, so I assume it's just return to vertical.)

Interesting. I have an MCP-X (the old brushed version) which I bought as an upgrade from an MSR-X. (Actually, I have two, as Wheelspin were selling them so cheaply when the brushless version came out that I bought a second one to have a supply of spare parts.)

How capable is the recovery mode in the new ones? With me it wouldn't be recovery from 3D, more recovery from basic flying like trying to turn without having to come to a static hover first...

Bravedan said:

 

One MAJOR problem is that some manufacturers state dimensions by external size (as Martin intimates) and some by the STATOR dimensions (the internal rotor max dimensions). EMax is a case in point as they identify the motor as 2826 by title, but this is not its overall size without shaft, which is variously stated but is on their own site stated as 47.5x39, with a drawing published showing these overall dimensions!

 

 

 

Ah! I had missed that in writing my post. That might explain why Hobbyking didn't have any motors matching that size and kV - I did think it seemed odd that the offered ranges (considering both kV and stated numbers of winds) were so far disjoint.

Thanks for the great information. I nearly did write in my original post that you'd really be the person to ask about this!

Also, your mention of "on their own site" made me check again, because I'd posted a link to emaxmotor.com which has no mention of case size being bigger! I have since found the page:

https://www.emaxmodel.com/gt2826.html

which does indeed include the drawing of external dimensions as you say - I assume this is the official site and emaxmotor.com is a reseller? Confusing!

A 2826/06 and a 2826/09 are both the same size, and will both look the same from the outside, but they are not equivalent motors.

"2826" simply means that the motor is 28mm in diameter and 26mm in length (not including the shaft).

The "/06" or "/09" refers to the number of turns of wire in the motor. This affects the "kV" rating of the motor, which is also often quoted for motors, and refers to the speed (in rpm) that the motor will turn for a particular supply voltage.

Using a motor with a different kV rating may require you to change any or all of the prop size, the battery pack cell count, and the ESC. If you just substitute a motor without doing the calculations then you could end up with insufficient power, or overload your motor/ESC.

If you want to use a different motor, it's better to instead look up the specs of the recommended one, and try to find another motor with the same kV rating. I found the specs of the Emax motor here:

http://www.emaxmotor.com/emax-gt-2826-p ... -1235.html

(Note that the name of the page is wrong - they describe the /06 one as equivalent to a "Power 32" not a "Power 25".)

This page says that the 2826/06 is a 710kV motor. It should be OK to substitute another 2826-size motor with similar kV rating. I had a quick look on the Hobbyking motor finder, but didn't find any, unfortunately - they seem to only sell significantly higher kV motors for this physical size.

If substituting parts (even ones with similar specs) into an electric powertrain, you may also want to check the result with a wattmeter to make sure that your motor, ESC and battery are all being asked to perform within their specified maximum current.

Do you think they deliberately put it on late in the day at that airshow so people could see the flames? The sky looks pretty dark in the video.

Well, when you say "turns over perfectly", does that include still having the same feel to the compression as it did before? Merely spinning round freely with little or no compression is a very bad sign!

But as you say, we can have a look at it tomorrow.

black oil/gunk coming from the exhaust and cylinder head itself

Oily residue from the exhaust is normal, though obviously more than usual may indicate something wrong. If there is genuinely residue coming out somewhere other than the exhaust or a tiny amount from the front bearing, this is definitely a problem! Have a look to see exactly where it seems to be coming from, and also check that everything that should be tight is. Is the plug still tight? Is the silencer still tight? Is the cylinder head still tight? Don't force anything tighter than it should be, but do check to see if things are loose. Heavy bits attached by a couple of screws (such as silencers, rear needle assemblies, etc) have a tendency to vibrate screws loose. I once lost one of the screws that held the backplate onto an OS 46 LA because they also held the rear needle assembly - when I noticed the problem one of the screws was gone and the other one holding the needle assembly was loose by several threads. (The engine still ran fine in that case though - I just noticed the needle valve rattling when I was refueling for another flight...)

Of course, if there is a lot of oily residue coming from the silencer it may have just covered everything else and there may not be a specific leak. I would also check the plug - if you ran the engine very rich it would produce a lot of residue and may have gummed up the plug. Everything covered in "black oil goop" sounds like very rich running to me.

Is there anything else unusual about the engine? Is there any discolouration to the engine after you've cleaned the oil off? Does it feel different when you turn it over slowly? Did you notice anything unusual before the engine cut (e.g. a loss of power)? What were you doing at the time (e.g. mid-throttle circuit flying, or part way through an aerobatic manouevre)?

You've included two electric-only WOT4s on your list of possibles, but you should also know that the "normal" WOT4 ARTF also now has designed-in electric support: http://ripmax.com/Item.aspx?ItemID=A-CF ... ry=010-020

Note that the new Chris Foss ARTFs all need an "IC" or "EP" option pack, sold separately. The latest version of the WOT4 ARTF now follows this approach.

I think most of the newer Seagull models also support electric as designed. It's pretty common on current ARTFs, though some do it better than others!

I keep all of my fuel planes indoors, hanging engine-upwards on the wall, so any fuel/oil residue inside the engine drops to the back of the engine. There was a thread about this on the forum a couple of years ago: viewtopic.php?f=22&t=3715&p=21037 - I keep meaning to update this with photos of what I now do (using horizontal storage rails and hooks from B&Q).

To avoid getting oil everywhere, I do two things:

• Clean the plane off with detergent at the field before putting it back in the car. I personally use "Flash" brand lemon flavour kitchen surface cleaning wipes from supermarket - I find these more effective than supermarket own-brand. Other people seem to use various detergent sprays and paper towels.

• Plug the silencer outlet with a small twist of paper towel or tissue. If you don't do this then you will definitely get drips as oil slowly runs down inside the silencer. Make sure to use a big enough twist that wedges in well to plug the hole, and do check that it's still there before you hang the plane up!

Some brands of fuel are much cleaner than others - usually the ones with a high synthetic oil content. I use Optipower "Optimix" fuel (18% fully synthetic oil) which I find very clean, even though I tend to run slightly rich for safety. This is slightly out of specification for some engines (I think it's Irvine that specify a minimum of 20% oil and minimum 3% castor), but I've never had a problem.

If you sit the plane on its undercarriage on a flat surface, rather than hanging up with prop shaft upwards, then you may get drips from the front bearing. I've never had any such problem since hanging the planes up.

Don't rely on things like cowl shape to keep oil in - if anything you're probably better off with a cowl-less aircraft where you can definitely get at the whole engine to clean it off with a detergent wipe!

I wouldn't bother keeping the plane in a bin bag - if that's necessary then you're not keeping it clean enough in the first place! If you're really worried then I'd just put something sacrificial like a piece of cardboard under the aircraft. You don't want to leave oil residue on the airframe even if dripping isn't a concern.

Another view, of course, is that if you're mostly interested in electric, and you're worried about mess, then why bother with an IC aircraft at all? If electric works for you then it's capable of powering anything designed for IC, not just foamies. The main things that might be an issue are flight time (a bigger battery adds a lot more weight than more fuel) and the cost of multiple batteries per aircraft so you don't have to sit around waiting for them to recharge. Most modern aircraft that support IC are also designed with electric support - the issue tends to come with older designs which you might need to modify to fit a battery hatch to avoid having to dismantle the whole thing to change the battery. Electric doesn't have to mean foamie!

martin said:

If you want the mains input GT Power charger you can have it. I never use it any more and I can't see when I would. The fan is noisy but the charger works. I had meant to list it on the forum Buy & Sell but never got round to it.

 

Do you want this?

I've got several chargers, but only two brands. I've never bought any of the big-name RC brands (Ripmax, Graupner, Overlander, etc), so I don't know what they're like. The reason for having so many

In the order I bought them, I have:

• A GT Power 200W charger that lives in my transmitter case (since there was a space in the flight case) but rarely gets used these days. This was my original charger. It's DC input only, and I also have a 200W mains PSU for it, which never gets used these days as when this charger does get used it's for field charging.
• A GT Power "606-D" 50W charger with mains or DC input, which never gets used. The reason I bought this is that the 200W mains PSU I had for my first charger had a very noisy fan, although the charger itself was silent other than when discharging. However, this charger does have an internal fan, which always runs when on mains power, so was actually more noisy than the combo! Additionally, the fan is actually noisier than it should be (sounds like a bearing problem).

A GT Power "X-Drive" 6 4-output charger (yes, I know Dave's opinions and to be honest I would agree but didn't think clearly enough when I bought it). This is actually the one I use most often for charging Tx and Rx batteries. If I were doing this again I wouldn't buy the 4-output charger but instead buy multiple separate small chargers, which were only about £20 each on Hobbyking last year (presumably more now due to the current state of the British Rouble). In any event, the 4-output model is less capable than 4 separate units (for example, not all of the ports support temperature sensors), yet the price is always barely less than 4 separate ones. A Revolectrix "Cellpro Powerlab 6" which is my main charger for LiPos. This is an expensive luxury, but it's easily the best charger I've ever used. It has lots of nice features that cheaper chargers don't, including the ability to do regenerative discharge of batteries under cycle (so rather than having to slowly discharge the battery through a resistor and waste the energy as heat, you can charge up the source battery as fast as that can handle, which means you can cycle and test batteries under more realistic loads). It has PC software that allows you to graph the performance of your batteries over time, measure internal resistance, get an accurate estimate of capacity remaining, and so on. It's rated up to 1000W which is far more than I will ever need (and actually needs 24V input).

If I were looking to start again and money were no object, I'd get the Cellpro again. If I were on a budget, I'd get one of the GT Power or related clones (Turnigy do a range that seem almost identical, as do others). If you only have one it's worth trying to get a higher-rated one (more than 50-60W, like say my 200W one) as this allows parallel charging of LiPos, which is the best way to quickly charge multiple LiPo packs with the same number of cells.

The reason I got the 4-output was to be able to charge multiple different packs at the same time (i.e. Tx, Rx, glow stick, etc), as I prefer to charge nickel batteries at 0.1C rate, which takes a while! As noted above, if I were doing this again I'd buy several small cheap chargers instead, giving more flexibility.

If you want the mains input GT Power charger you can have it. I never use it any more and I can't see when I would. The fan is noisy but the charger works. I had meant to list it on the forum Buy & Sell but never got round to it.

As others have noted, a second-hand car battery makes a good field-charging power source. You can use your LiPo charger to recharge it if you have some sort of mains power input. Be aware that most car batteries are not designed to be discharged more than about 15% (so a 60Ah battery is only really designed to have about 10Ah taken out of it before it's recharged). Going further than this (and in particular leaving the battery in a partially-discharged state) will shorten the life of the battery. Then again, if you got it second-hand for £10 or so then you may consider that it's fine to do this and just get another when it won't hold an adequate charge any more.

If you have a charger with only DC input, an old laptop PSU makes a good power source, especially if you can find one with a standard type of plug like one of the coaxial DC plugs. Check your charger's rated input voltage - many can go to 15 or 18 volts and some even higher, and there are plenty of laptops that use PSUs around the 12-18V mark. Many laptop PSUs will put out 80-90W which is more than sufficient for a small charger as it can't draw more than that anyway. These are usually fanless, which is good since you will obviously want to be in the room with your LiPos while they are charging! You may need to solder up a suitable adaptor lead - Maplin sell coax sockets in all the different sizes (measure the plug on your PSU before buying the socket). I also have a GT Power 15V PSU which I bought with one of my chargers (probably the 4-output one), which is basically an unbranded laptop style PSU. eBay is also a good inexpensive source of this type of PSU - they are sold as aftermarket replacements for older laptops. You may even find something in a car boot sale or the like, or you may have an old dead laptop, LCD monitor, etc kicking around at home. Note that the small PSU-in-plug type adaptors are very unlikely to put out enough power!

If you've never done it before then it might be a better idea to get a foam one first! We've had a couple of CAMFC slope soaring outings, and generally the people who turned up with built-up balsa gliders as their first attempt didn't really get much flying in, as a couple of heavy arrivals would lead to more repairs than could be done at the field.

Dave recommended the Flying Wings Slipstream, and I can certainly vouch for its beginner-friendliness as well as high resilience (though I recommend reinforcing the Correx wingtips with fibreglass tape as otherwise they can be ripped off in a crash). I have had many more crashes than actual landings, and other than wingtip damage the only repairs I've had to do were where the tape covering lost strength due to heat/sunlight.

As to how you land, that depends a lot on the site, the model, and conditions on the day! Flying along the slope as you suggest means you're landing in a major crosswind, but if you fly downwind and land into wind then you're probably landing downhill! (Also, not every site has enough space behind to be able to land into wind.)

Speaking as still a beginner to slope soaring, I would say that the biggest things I found hard to get used to in transitioning from power flying were:

* Using down elevator as a matter of course. If you want to penetrate out into the wind you will need to use down. Things like banking into a turn and pushing down rather than pulling back took a little while to get used to.

* Having much bigger throws than I was used to, but using only a tiny bit in the middle for a lot of flying. You'll probably be flying at a much wider range of airspeeds than you might be used to, and so want big throws to give you some control at almost-stalling speeds, but then using tiny fine adjustments to fly straight and level. Expo helps, but if you use too much then the big control movements end up a bit all-or-nothing.

* Being aware of wind direction and speed to a much greater degree than I would for power flying. For example, you need to launch straight into wind. If the wind were blowing diagonally down our runway you'd probably still take off straight along the runway, but when launching a glider you don't want to do that.

* Simply flying in much higher wind than I would ever consider for power flying! I hadn't really considered the need to look at wind conditions and maybe re-trim the model until I turned up at Mill Hill in a 20-25mph wind with my Slipstream still trimmed for the last time I used it, in 8-10mph wind at Jack and Jill. I think the difference between the two needed something like 10-12 clicks of down elevator trim to remove most of the reflex on the wing - before I did that every launch just went back over my head! I've never had my hat blow off my head while flying before, either (I've since bought a sailing cap that ties on after seeing Rod's one).

A useful thing to practice (and to be honest the main thing I still do when I go slope soaring) is to fly figure eights along the slope, allowing the aircraft to drift slightly downwind (back towards you) on the cross legs, and always turning into wind (alternately left and right) at the ends of the slope. Try to maintain a constant altitude.

I'm sure other people more expert than me may have more to add...

You could try one of them newish Li-FePO4 / A123, 2 cell batteys, they come in all sizes and mAh's! They do cost a bit more than a standard battery, but give you so much more! "just a thought".....

I was going to suggest that myself! They don't have to be expensive:

https://hobbyking.com/en_us/zippy-fligh ... -pack.html

https://hobbyking.com/en_us/zippy-fligh ... -pack.html

https://hobbyking.com/en_us/turnigy-nan ... -pack.html

... etc ...

They also have the advantage of being smaller and lighter, and providing a much better discharge rate (so you don't have to put in a huge pack just to get the current rating for multiple heavy servos). Even the small ones are fine for 4-5 servo planes. My WOT4 with 4x Hitec HS5485HB digitals and 1x Futaba S3001 flies fine on a 700mAh Zippy Flightmax - though I am tempted to up this to 1100mAh. Either the 700 or 1100 should be fine in a Cougar.

Also, you can check them at the field with your LiPo balance checker, and if it's low you can top it up with LiPo charger in half an hour or so. I love them as there is no more worrying about when I charged the receiver pack or whether it has self-discharged - just connect it to the charger and if it's already full charging will terminate within 2-3 minutes. Compare that to NiMH which take 1 hour plus just to notice that the pack is already charged!

(On a tangentially related note, why on earth have Hobbyking decided to mess up their site so that it's no longer possible to link directly to an item in a particular warehouse? Sigh.)

Yes, my main concern with that prop on a 35 was how quickly the engine would be able to spin it up on demand. A 12in IC prop has a fair amount of momentum.

I think 12x7 in that list has to be a mistake. I'd expect to see a 12x7 on a .55 not a .35!

12.25x3.75 might be a bit on the heavy side. I used a 12x4 on several different .46 engines (albeit not an AX) and it was fine there but it appeared to be at the upper end of what the engine could cope with. That said, the other propellers in the recommended list (e.g. 10x7, 11x6) are also ones I'd expect to see on a .40 or .46.

There is a useful rule of thumb to compare the rough load that a propeller places on the engine or motor, which is to take the square of the diameter multiplied by the pitch. (This is proportional to the notional "pitch volume" swept by the propeller.) You can use whichever units you want (inches, millimetres, etc) as long as you're consistent between the ones you're comparing. This is only a rough approximation - many engines have quite a limited rpm range for good torque so you're more limited in prop choice than you might think. It's more useful for working out what diameter/pitch you should be looking at when you decide to try going up or down on one or other.

For example, based on the list you posted:

* 10 x 6 -> load value 600 (10 * 10 * 6)

* 10 x 7 -> load value 700

* 11 x 6 -> load value 726

* 12 x 7 -> load value 1008 (note how this is MUCH more than the others)

The others discussed:

* 12 x 4 -> load value 576

* 12.25 * 3.75 -> load value 563

As Dave said, for a fun-fly type plane (and indeed anything else that you want to fly slowly but with max control), you want to be looking at the largest practical diameter and the lowest practical pitch. The prop you have sounds like a good option if the engine is happy with it.

It depends on how serious you are! I know that the people who enter rubber free-flight competitions do things like buying only sealed boxes of rubber, making up individual motors and bagging these individually, and testing each such motor once during the trimming flights on the day of competition, so they can use the best ones for the more important competitive flights...

Personally, I don't take particularly good care of my rubber. I do use lube on it when flying (I'm currently using the silicone oil from Free Flight Supplies, but I know Duncan uses KY Jelly), and I keep it in a plastic bag mostly to prevent this from then getting all over the model (and because putting the motor and lube into a plastic bag is the cleanest way to actually lubricate the motor). I haven't put talc on the rubber I last used, but I haven't taken that out of the bag since the club BBQ competition, so I don't know what state it's in. That motor was losing quite a bit of power by the end of that day anyway.

My understanding of the rationale behind talc is that it's not about protecting the rubber so much as absorbing water and/or oil that may be around. I certainly keep wing bands for IC planes in talc, as it seems to help with any traces of oil (or the detergent wipes used to clean it off). Generally though, I regard any rubber part (whether wing bands or motors) as essentially a consumable - even with the best possible care it won't last forever.

I have a stock of new rubber (also from Free Flight Supplies), and I simply keep this in a ziploc-type bag with air expelled, in a cupboard to keep it cool and away from the light. Sunlight and heat are definitely enemies of rubber (they also destroy a lot of other things such as the glue on the tape on foamies). I have heard of metal biscuit tins being used for this (also lightproof and reasonably airtight), but I didn't have one handy. I just folded it end-to-end repeatedly until it fitted in the bag.

I am sure there are 3 "airworthy" Mosquito's still!

It turns out that there are, but only since about a week ago!

I had been aware of two:

* KA114/N114KA is a restoration using most of the original metal but with all new wooden parts made by a company in New Zealand a couple of years ago, on behalf of an owner in the US. First post-restoration flight was 29th September 2012. Annoyingly, when I was in NZ a couple of years ago I was a couple of weeks too late to catch its last NZ airshow appearances before it was shipped to the US.

* VR796/C-FHMJ is a mostly-original airworthy one in Canada - one of the RAF surplus ones that was sold to Canada in the 50s for use in mapping their vast northern expanses. There is a good TV programme about the restoration, which is well worth a watch. First post-restoration flight was 16th June 2014.

What I hadn't realised was that the same people in NZ who rebuilt KA114 have just had the first post-restoration flight of another Mosquito: TV959/ZK-FHC. First post-restoration flight was 26th September 2016 - i.e. Monday just gone!

Ooh! A real 109 rather than a Buchon!

Newly built Mosquito? You mean the one built in NZ and now in the US?

Yes I'm doing the u/c mod. The nylon nuts are there because I cracked the ply and damaged the foam in the rx bay in an emergency landing as I got a "signal loss" warning. It takes 2 secs to replace the nuts and not a day to fix the fus.

You need a thicker bit of ply, then! I certainly have cracked one bit of ply, but it's not hard to make another, and you could always make a spare and keep it in your box... Generally I find that the undercarriage is the one bit that survives when I crash yet another WOT-4 foamie!

Also, can anyone remember how long their bolts were???

Having just looked up the relevant Model Fixings order, when I was using M3 socket cap screws they were 60mm long. However, that's only enough to get through into a T-nut, not to protrude the other side as you'd need if you're using studding with a plain nut on the end. 65-70mm is probably about right, but personally I would measure it to be sure (use a spare bit of pushrod or something, a pen, and a ruler). I can't get to the old bits of studding right now to measure them. If you're using the breakaway nuts idea then the length becomes quite critical.