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Oct 31, 2017, 06:02 PM
Mumbling in the corner.
flyboy2610's Avatar
Sounds like a re-covering job is in order. Unfortunate, but ya gotta do what ya gotta do!
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Nov 05, 2017, 10:36 AM
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Open day at WAMASC


Today was the AWA-WAMASC RC Expo day Aeromodellers West Australia - West Australian Model Aero Sports Club), and I needed to do some volunteer hours for them. I ended up as the announcer - compere armed with a radio mic, and it was a great day. Lots of great flying and very impressive models. I've got a bunch of pictures online at some startup that does internet searches or something I hear - https://drive.google.com/drive/folde...TQ?usp=sharing
Great except for this guy on the sound system who wouldn't shut up. Everyone was there to see the giant 4-turbine 747, 1/12 scale. See for yourself:
WAMASC Expo 2017 - World's Largest RC 747 - Andy Herzfeld (5 min 9 sec)

I wanted to see the Stearman PT-17 with the Moki 7-cylinder 250cc, but it didn't fly. You can see how nice it is in the goggle drive photos.
Nov 12, 2017, 09:00 AM
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Thread OP
I just did some tests on different clear coats for fuel-proofing, at least for glow fuel. In short, we knew epoxy resin is totally fuel resistant, but I found that oil based polyurethane is suitable too. Matter of fact I think I used it on the firewall of this model after the first crash, I don't really remember but it sure doesn't look like the epoxy around it. I tested some others I thought would work, but they didn't. See:
https://www.rcgroups.com/forums/show...60-kit-Samsara
Nov 21, 2017, 11:13 AM
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Thread OP

Building a Trainer 60?


Hi, if you've found this thread because you're interested in the RCM Trainer series, there's a lot of great advice that was given to me by many very competent model builders and flyers. I recommend you make your way through the build, even though it's a long log. The build part of it is the earlier section, though with a lot of discussion along the way. Feel free to contact me or post your questions here for others to help you with any time you like.

There are still companies making and selling kits of this design, eg. Eureka Aircraft Company http://www.eurekaaircraft.com/ and they offer several options on kits of this design: http://www.eurekaaircraft.com/plan_kits/rcm-trainer.htm They make just a few modifications to the original Bridi design, and in fact it turns out they made just about the same changes I did - obviously few people still build an early 70's-style hardwood engine rail mounting, it's just so much easier and better to use a hobby store commercial engine mount. They also simplify the centre wing rib(s) just as I did here - instead of making one big thick one and trying to bevel the dihedral angle into it, they simply make normal ribs and lean the centremost (inboard) rib of each wing panel over at a small angle to allow for the dihedral of the wing. But there's not much else, it's basically the same design RCM published as designed by Joe Bridi in the early 70's. I did one thing though - I extended the wingspan by 6", or one extra rib at the same spacing as the others, each side. They list the other modifications, I'll quote from their page:
"1. Changed to a solid firewall, with standard motor mount. As a result of this, I straightened out the nose of the plane, so it is easier to build, and there will be no problem fitting or cooling any engines / motors. Most people changed this when it was scratch built anyway.
2. Firewall is set to 2 degrees right thrust, and 2 degrees down thrust, so the engine is at the proper angles automatically.
3. The 3/16" balsa nose doublers are cut to automatically place the fire wall at the proper location and angles. The left and right set are different, so the left side set will be marked on the wood
4. The 1/16" PLY landing gear braces are replaced with 1/4" braces to make the gear mounting stronger
5. The center of the wing has been modified... (see above)
6. The wing ribs have both building tabs for accurate building without a wing jig, and 1/4" holes for use with a wing jig."

Other than #6, I think I made all those exact changes. You might notice I also built in a simple hatch held down with 2 bolts, and a divider tray between the fuel tank compartment and battery area. I quite like the way that turned out and it works very well for me in the field, but remember it's an ad hoc mod. I made myself and you might wish to do the same.

Anyway, obviously the "build" is long since over and I've been flying the model for some time now. I'm going to continue the flight logs, not every single day's flying but just when it's worth reporting, on my blog page (click my name to the left, and look for the RCM Trainer 60 headings, I'll make sure they're labelled). If I modify the model itself or anything major happens to it, I'll also post it in my blog but I'll post it in this thread too. Otherwise, I won't be adding too much here off my own initiative, just what I think is relevant to people considering this design.

However, if you're building, flying or considering the RCM Trainer 60 (or any of the other versions of this design, such as the RCM Advanced Trainer, RCM Trainer Jr., RCM Trianer 40, RCM Trainer... which are often the same design simply re-published later, with or without further changes but always minor if there were any), please feel free to post anything relevant right here, and I'll try to help. I'm sure others will too, that's what RC is like. They're great people. I hope you *do* try this design. If you are interested in building your own RC planes, this is a great design to start out with, it's not a basic trainer and if you're learning to fly on it, you WILL need an instructor! Trust me on this. But it's definitely much more fun than most other high-wing trainer designs. Faster, more agile, more capable, and yes, maybe a little more challenging. But as soon as you've got past basic turns and got used to the idea of flying, those super-stable and conservative club basic trainers get a little unsatisfying, pretty quick. I've become very comfortable flying around and come a long way on this one, but I still think it's great fun, and so do many other I've heard from. Even people who fly much more advanced planes sometimes keep one around, just for fun. There's also a matching set of floats for this design too, if you check Outerzone. That could be very interesting!

OK so the floor is yours. I know there's probably nobody left by now, but like I say, if someone DOES become interested in this design, by all means please do use this thread to find some help, ask questions, and generally put it to work. I'd be more than happy to help if I can. Best of luck.
Mar 05, 2019, 03:28 PM
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Thread OP
Current plan is to clean up this model and start flying it again, as it's been so long since I could go flying I'm too rusty for my Venture 60. So back to the Ol' Faithful RCM Trainer 60 for a while. While it was *sweet* with a Saito FA-56, I intend to fit the FA-82B to it. I've got the 56 in it now and I'll get it going again with that, then switch to the bigger engine. From the start that was the intended engine but once I had the 56 I fitted that and found it a great match. With this model's thick wing and draggy body it won't go a great deal faster with the bigger, more powerful engine, but it will have shorter take-offs and better climb and acceleration. Let me say, with the FA-56 this model had good performance for a trainer as it was, the 56 was definitely adequate, but having flown it many times now I found myself wishing for a little more poke sometimes.
Anyway it'll be a while till I get it flying. I am considering completely re-covering it, the fuselage is looking a bit tatty these days and the wing is full of sand from the last crash, I can hear it shifting around in there. It will only wear things out.
I'll try not to be so fine-grained in my posts and coverage this time Pic's when something happens.


Anyone building an RCM Trainer 60 or the other Bridi RCM trainer designs, please say hi and let us all know you're doing it. This is a great little model, a good trainer though let's not forget it's an Advanced trainer design, not a super-gentle, very slow putt-putt. It's actually good fun, I regard it as a mild sports model suitable for training, put it that way. I see a few builds of this or other similar RCM designs on RCG and there are some kits around the place of this classic design, so I'd love to see your pic's and flight or build reports. Thx.
Sep 22, 2019, 09:13 AM
Perpetual Novice
ernardW, others

I stumbled onto this RCM Trainer '60 thread and thought I would respond in hopes of giving myself an inspiration. And I have a question at the end...

I remain a big fan of this Bridi design, I regard the kit as one of the best all-around airplanes I've owned. Unfortunately, years ago I pulled up while making a highspeed, inverted lowpass over the runway. Simply, was paying attention to work thinking in my head, not my flying. As I was able to salvage the vertical stab and landing gear, I've always planned to rebuild (takes very little for me to regard an otherwise new build as rebuild). And over the years I've acquired '20 & '40 Trainer kits along w/ a '60 laser cut balsa clone kit (not even sure who's). My goal is to build all three versions, my tribute to the old school days. And need for inspiration.

Getting to my question; I took out much of the dihedral so as to have more responsive flight characteristics but don't recall what I used. I believe the original design called for ~1 1/4" height @ one tip (other flat on table). I am guessing that I reduced it to 50%. I've seen the '60 as a flat wing but don't particularly like the LQQK; although it might be a great flyer.

Any thoughts?
Sep 22, 2019, 09:39 AM
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Thread OP
Thanks for posting, been a while since anyone was here. OK my thoughts, yes 1-1/4" is the dihedral measurement on the plans under each wing-tip, and I always wished it were less once I started flying the plane. I have long intended to build another wing with less, or no dihedral. How much then? I really don't know enough about aero design to say, but halving it sounds like a good start.
That said, you COULD play with modifying a similar design in an RC simulator. I put in a lot of hours on ClearView SE while learning and it was a great help. It's highly data-driven, meaning you can play with the data in many files to control just about any aspect of it. The Aileron Trainer model provided with the standard version is not too far off in behaviour to the RCM Trainer 60 / Advanced Trainer, IMO. Now, I don't know even nearly enough about it to say what variables you need to change, but somewhere in the data files for each model, you would add or edit a line to control it. Only trouble is, the model will still LOOk the same in the sim as you'd still be using a 3d constuct with that amount of dihedral baked into it.
I've always thought the dihedral was a little too much in this model for an advanced trainer. On one hand, you use dihedral in a high-wing trainer for all the understood reasons - stability, self-righting, and the possibility that it might be built without ailerons. In this day and age that last point doesn't really apply. With this model you really need to use coordinated turns, ie a little rudder as you bank, so the roll-yaw coupling you get with dihedral is less critical IMO. It also means there are certain manoeuvres that you can't do easily, like a wing-over, and others unless you actually try to neutralise the roll coupling by banking opposite to the rudder direction... maybe I'm not explaining this too well but basically I wanted to try this model without so much roll-yaw coupling thanks to all that dihedral.
I haven't built enough models to know how much is enough, but I suspect you could reduce the dihedral down quite a lot and still see it work, say down to 1/4 of the original amount. I'd like it to be subtle, if it's there at all. It might indeed look a little funny with a flat wing, but up in the air, who's to know? I guess all you can do is build one and try it out... or do a degree in aeronautical engineering and calculate. The sim approach, altering the variables, might offer some help.
Final thought, I have seen a couple of modern pattern designs with very slight dihedral, I'll try and describe it. The wing has slight taper in chord, viewed from above. But viewed from the front, the top of the wing is dead flat across the whole span, so the bottom spar on each side makes a very slight Vee shape, since the taper means that the wing thickness reduces towards the tips and the top surface is flat. So this isn't very much dihedral but even that is considered worth keeping, rather than simply having the taper even from top-to-bottom, so that looking front on you'd have a kind of diamond shape.
Summary, I think even less than half the original dihedral would be interesting to try... but I really can't predict how it'll behave. If you do build a modified wing, PLEASE post back here and let us know how it goes!
I do intend to fix up my RCM Trainer 60, Ol' Faithful as I think of it (or Kelly's Axe - "It's had 2 new handles and it's on its third head, but it's still my old axe"... an axe has a handle and a head, right? So you replace both and what's left of the old one, not much. Maybe the wedge...? My trainer has most of the original woodwork in place, though I replaced everything forward of the LE after a crash, but just about all the fittings inside have been replaced at least once and often more). I'm so rusty after very little flying recently, I want to go back to a trainer for a while before I risk any new builds on my forgetful thumbs.
Sep 22, 2019, 03:19 PM
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Thread OP
FS3733, since you asked for thoughts on dihedral I've also been thinking, this is pretty sporty for a trainer, compared to some. It's also been published as the Bridi/RCM "Advanced Trainer", AFAIK the same design.
I mostly flew mine with a Saito FA-56, which worked out great, it's a good size, weight and power for this model. But I originally planned to use my FA-82B, the first RC engine I ever bought. After flying the model for a while there were two things in particular I started to really want - less dihedral and more power.
I built mine from plans, not a kit, so I added a few minor changes from the original to simplify and slightly modernise it, mostly at the nose. First, I got rid of the curved taper from the windshield to the front of the cowl cheeks, which was built in by shaping the original hardwood engine mounting rails. I was using a store-bought plastic engine mount, as almost everybody does now, so I didn't need those rails and there'd be nothing to make those cheeks curve inwards.
These days the only kit I'm aware of for the RCM Trainer 60 (or whatever name it's under) is by Eureka Aircraft Co., https://www.eurekaaircraft.com/plan_...cm-trainer.htm. I read some posts by someone saying that it was pretty good. That page lists 6 changes made from the original design, and I built mine before hearing of their version but it turns out I made just about the exact same changes. They're all pretty obvious.
Anyway, one possible option for you is that they offer foam wing cores to suit the RCM Trainer. They do a full kit with the wood, build-up wing for $US120 or with the foam version for $US160, that sounds pretty good to me... these are short kits, however, so they will need some input from the builder. I would really like to set myself up to make foam-cored wings, and I did find that the local foam supplier here is able to cut cores from a template (I did this for the D-tube wing skins for my next project, a much-modified Ugly Stik. See posts 432 and 351, and earlier.
(Just looking through their site now they have several kits I'd like, particularly the Bridi Dirty Birdy and Kaos 90. I already wanted to build both, I've got a Saito FA-182 flat twin I'd love to chuck in a Kaos 90, and I really want to try a classic old pattern plane. The Dirty Birdy is certainly that and at that price, it could be a winner).
So my take is that this may be a trainer, but it's not for first-time flyers, as you know. It's reasonably sporty for a high-wing trainer type, more like a Decathlon. Therefore I think hot-rodding it with reduced dihedral and more power is a good idea, you'd end up with a model with more ability to fly interesting manoeuvres, which I believe are really restricted by the amount of dihedral in it. I've always thought it was a bit of an odd bird... as a trainer it's certainly not for your very first lesson, and the name Advanced Trainer is well suited. It was especially for wing-overs that I really started to wish it had a flat wing, or at least flatter. How flat? That's the question, isn't it. I've been told you want *some* dihedral in almost all cases, all but for all-out 3d, pattern and certain other performance-oriented models, but I think it would be interesting to try it with none. My Stik will have zero dihedral, at least for the first wing. If I find it too full-on then I may build another with some, but it wouldn't be much.
Adding power by dint of a bigger engine, I'm sure I would want reduced dihedral in that case too. There's just too much as it is. I did install the 82 for a while, I found it was great for take-offs, climbs and certain manoeuvres but it really didn't raise the top speed by a great deal, as I guess drag builds up very rapidly in a design like this, it's decidedly non-sleek. So it's about flying for fun, not fast-ness.
If you don't wish to use zero dihedral then my suggestion might be for say, half an inch under each wingtip, as opposed to the 1-1/4" in the plans. But I'm absolutely guessing, I've never had the chance to compare models that were the same otherwise but for the amount of dihedral.
I should point out, I modified this one by extending the span by 6", one additional rib bay each wing panel. So the 1-1/4" dimension applies under the 2nd ribs in from the tips, not the outer-most ribs. I've never bothered to measure that final distance. It's another reason I'd eventually like to build a new wing for it, so I can try it with the original span and wing area intended from the original design.
Maybe my changes have magnified the roll-yaw coupling; the idea was to reduce wing loading. As it is, it sinks fast and is definitely not a "floater", even though I kept the all-up weight right on the original spec. I forget what that was, I think off-hand it's 6.25 or 6.5lb, but mine basically came out right on that. Even so with the span reduced from what I've got back to the original figure (I think 59.5"? Something like that) it would be slightly faster, slight sink-ier and slightly "funner", I expect.
I've had a new wing in mind for a while, but one last comment on the one I built... it was my first upon entering the hobby (not counting 30 years ago when I built a Carl Goldberg Gentle Lady glider, which never flew) and I had a bit to learn, needed to get experience, but it's a good design and it turned out really well. It wasn't difficult to get it right. I included a little wash-out, maybe 3mm / 1/8" I think. It's all balsa, I didn't use any fancy spruce spars or anything, except for a fibreglass wrap around the centre. It's light at about 650g and amazingly stiff for that weight. I haven't tried really forcing it, but I can give it a pretty good twist with my hands and it stands up to it.
That model has also been though one serious and several minor crashes, and of course all sorts of bumps, dings and knocks, and the wing has withstood them all with barely any damage. I was amazed to find it basically unscratched after the major crash - that was a power-on, near-vertical dive straight into the ground. I was totally out of control and had no idea how to fly yet, I was well out of my depth. Hubris! Arrogance! And punished for it! The entire front of the model was smashed (see earlier in the build log, I can't say what page) from the windshield forward and I rebuilt it, but the rubber band wing mounting did its job and the wing came away and was spared all damage. I didn't even need to fix any holes in the covering, it literally just had one scratch, not a big one either.
For that matter, the entire fuselage came out of that remarkably well. The battery at the time was mounted behind the servo compartment, so it came loose and broke through a bulkhead, but that was the only real damage other than the smashed front. The vertical fin broke off but I'd already broken it off a few times before it even flew, that was no trouble to fix. The whole design is rugged and durable... over-engineered and over-weight, even, but considering its intended role I think that's reasonable, and it certainly paid off that time.
Anyway good luck, I'd love to hear about it if you do build a new wing. Please post it here if you do!
Jan 14, 2020, 08:00 PM
Registered User
Any chance I could get your PT60 plans from you, after your done building yours? I'd be will to pay something for them. I inherited my first build and they didn't have the plans.
Jan 15, 2020, 08:11 AM
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Thread OP
Quote:
Originally Posted by Binerman
Any chance I could get your PT60 plans from you, after your done building yours? I'd be will to pay something for them. I inherited my first build and they didn't have the plans.
Hi, I haven't found any PT-60 plans available online but there is the Great Planes PT-40, plans for which are available free on outerzone.co.uk
https://outerzone.co.uk/plan_details.asp?ID=8015
Also I saw an older thread where someone wanted the same plans, and someone replied with a link you can use to purchase a new set of plans from Great Planes - /forums/showthread.php?1778486-Wing-Plans-for-Great-Planes-PT-60-Trainer
or try http://www.greatplanes.com/parts/gpma0119pl.php
Failing that, this RCM Trainer 60 is a good choice too. If you elect to go with that then please feel free to post any questions regarding the build right here, and you should find just about every possible question and answer already, somewhere in this giant, rambling 100+ page build log - it's just a matter of wading through and finding it. I've got hundreds of photos from when I built it, still on my hard drive, so even if you're building some other design and get stuck there's likely a solution you can adapt from there.
I also found someone's old build log for a PT-60, though I haven't read it yet or seen if it's any good. https://www.rcuniverse.com/forum/kit...ld-thread.html


Please let us know what you decide to do and how it goes! Best of luck
PS I built this trainer from downloaded plans... I never got them printed on a big A0 or A1-type sheet of paper at a plan printer's shop. Instead, I use Adobe Reader printing out in Poster mode, and copy/paste the section I want to a new file (using GIMP) then print that across however many pages of standard paper, on my cheap inkjet. Even the biggest pieces, like the fuselage sides or a wing panel, take 4 or maybe half a dozen to 8 pages. Most are 2 or 3. I find that more convenient than one giant rolled plan, but others prefer to work that way.
Printing that way Adobe adds alignment marks. I use a steel ruler and sharp blade to trim one edge off then double-sided tape to join them up very carefully, using a straight edge to make sure the lines of the drawing (not the edges of the paper - you don't know if each piece aligns the same way as it goes through the printer!!) are all exactly lined up.
If you want the same plans I used they are there to download on post number 1 of this build log, but they're RCM Trainer 60 plans, not the Great Planes PT-60.
EDIT - PS over at eurekaaircraft.com they have full kits of the RCM Trainer 60 and I notice they also sell just the foam wing cores. I've always wanted to try a foam wing and I've also been interested in a 2nd wing for this model, might be the way to go? Only $45 US, though shipping to Aust. would be more than that no doubt
Last edited by BernardW; Jan 15, 2020 at 01:03 PM.
Jan 15, 2020, 12:11 PM
Registered User
Even in the States, I found shipping made the foam wings pretty expensive.

I had them make wings for a Big John bipe, and they were light, straight, and strong.
Jan 15, 2020, 01:15 PM
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Thread OP
I can't believe I forgot this, but I did get half a wing core cut for me at a local foam shop and it was about $30 ($AU) and a 2nd one would have only cost another ten I believe. I used it to mould a balsa LE but they were familiar with the type of thing and can make cores up from either templates or a DXF file. I had a lot of trouble converting the PDF's of the aerofoil section I wanted into a DXF they could use, so i gave up and just made them a physical template out of thin sheet metal. The result was just fine at a good price.
If anyone in Perth or West Aust is wondering, I got that core cut at Foam Sales in Myaree, if you build any foamies in Perth I'm sure you would know this place.
Last edited by BernardW; Jan 16, 2020 at 02:25 AM.
Jan 15, 2020, 05:46 PM
Registered User
Yeah, makes a lot more sense to have it done locally.
Jan 21, 2020, 11:42 AM
Perpetual Novice

LQQKing for that inspiration


I enjoyed all the Bridi comments and the luv for his Trainer 60. I dug through my stock and located a 60 short kit, 2 ea. complete Birdi Krafty 40 kits, and a complete Bridi Trainer 20 kit. I'm now leaning towards 1/2" dihedral @ each 60 wing tip.- I'm sure I used 3/4" on my original (reduced from 1-1/4" on plans). LQQKing to make it a bit more sporty & still appear stock_ish. I will likely keep the smaller ones @ stock values. They will make fun student trainers following some flight time on Nexstar's.

Still LQQKing for my original 60 Kit/Box as I always keep my plans in their original box and I keep all my boxes. My vision: Build a livery of the Bridi Trainers. I'm betting I can easily convert the lines of the Krafty to those of the Triner 40 to easily complete a livery.

Now to find that ambition...
Feb 05, 2020, 04:22 AM
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Thread OP
Quote:
Originally Posted by fss3733
...My vision: Build a livery of the Bridi Trainers. ...
That's a great vision! I'd love to try some of the others. I find the Trainer 60, aka Advanced Trainer et al, to be just that, Advanced as far as trainers go. It's a little more sporty, needs a little more air-speed and sinks a little faster than the sort of trainer you'd do your very first lessons on. You COULD use it that way but I'd strongly advise doing so with a proper qualified club-endorsed instructor, and definitely a buddy box system. Better yet do what I did and get all the practice you can at home on an RC Simulator, those things are worth every penny.
I believe some of the other Bridi trainer series models are a little more gentle in their behaviour, more suited to someone who is having their first attempts at RC flying. That means they're forgiving, stable and usually pretty slow... sometimes that's how you want to fly long after your lessons are finished too. But for me, I do like going a touch faster. I enjoy flinging them around a little more than that. That suits the Advanced Trainer / Trainer 60 etc.
The Advanced Trainer / Trainer 60, and from what I hear the Junior version, all require coordinated turns, rudder as well as ailerons and elevator. One person posting early in the thread said he keeps a Trainer 60 around just to get his thumbs warmed up again at the start of each flying season before flying the more advanced models, as it's good discipline being required to use both sticks for a turn.
I remember at one early lesson before I got my solo wings, somehow I'd decided Hey Look you only need ailerons!, and it was true, I could get around corners that way, but I did find the accuracy of the turns was terrible, I was exiting at anything but the 90 degrees I wanted and those turns were very ragged. Then when I started using just that touch of rudder with it too, suddenly I had proper control again. The instructor noticed it straight away, after flying all day making these rotten turns and him getting frustrated, all of a sudden I was back on track making good turns. And that's all it was, coordinated turns using rudder. Worth remembering, if you're still doing your flight lessons. Sure, some trainers don't *need* rudder for coordinated turns, but it's excellent practice and a great habit to get into, because most other models definitely do need it.


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