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Jul 24, 2017, 04:26 PM
What could possibly go wrong?
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RCM Trainer 60


I'd been asked by a couple of people to desctibe this design in its design role as a trainer, here goes. I'd say it's really pretty good, but these days I don't know any in production as a kit or ARF. Not too many people would be mad enough now to build their own trainer from scratch as I did, but I love it. Now I'm flying solo, it's stable and easy to fly, so long as you set that CG forwards. The plan shows the forward point at the back edge of the wing spar, my last instructor adjusted it to the front edge, and that's pretty good, positive stability and it tends to return to stable flight.

What I like about it though, is it's not a *basic* trainer, in fact this is almost the same design as the RCM Advanced Trainer, and the plain RCM Trainer (very minor differences with the latter, can't find any with the advanced). It's faster, for one thing, but I hasten to add it's still very easy to fly, you just need to keep up a little airspeed, so those turns come up a little sooner but it's no problem and still well behaved. As soon as the airspeed drops below a certain point it really starts sinking. That takes away one problem I find with today's light ARF trainers, they float and sometimes don't want to settle. You can always point the nose down and dive, but you'll build up too much speed, lessons teach you to sink for the ground, not dive for it, when it's time to approach for landing. Turns are good and steady, but I just found out you do want to learn to use coordinated turns, with rudder that is, soon as possible, you'll have a lot more control over how those turns come out. I'm powering mine with a Saito FA-56 4-stroke, if you're a beginner and you place a recommended .60 2-stroke in there you'll have more power than you'll want. The Saito is a great match for it, enough power without overdoing it, and never lacking.

It's a rugged design, just as well because early on I got cocky and tried to solo it before I was ready, and pranged it. It was also badly trimmed and with a stronger engine and thrusty prop, it just wouldn't slow down enough for me to handle, and ended up going nose-first into the ground at speed. The front was damaged but that was all, the wing didnt' get a scratch, and the build log shows that repairs weren't that big a deal. If you have a good place to work it could have been done in a day or two, I took longer.

I've seen other people post that they've long since moved onto more advanced designs, but still enjoy flying this one for its own sake. It looks like a classic, boring, stodgy old trainer, actually like a Cessna 152D I think, but it's a nice flyer and surprisingly agile, it'll do much more than plain old circuits. I've tried brief inverted flight and it was a ton easier than in anything else I've tried with a high wing. I think there's no reason not to recommend it if you want to learn to fly and are prepared to build your own, BUT... you *must* take lessons with an instructor, use a buddy box or some kind of dual control, and practice at home on a simulator. Do so and this model will take you all the way.
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Jul 25, 2017, 05:56 PM
Modeling Retread
I built two RCM Trainer 40s, same basic design, just smaller for a 0.40 ci 2C engine. I didn't dork the first one immediately, but when I did, I too went straight in destroying the fuselage through the wing saddle. I built a new front end with heavy duty foam board that I covered with Coverite for extra strength. I flew that for a long time. The symmetrical airfoil makes it much more aerobatic. The dihedral, however, works against that.

I built a second RCM Trainer 40 with modifications. I made it a tail dragger and eliminated the dihedral. Now since it's a high wing it still has some effective dihedral but it was way better suited for aerobatics. I do know what happened to it. I did a split S from a reasonable altitude but suddenly the half loop became much bigger than normal. I was still a novice flyer in some ways so, rather than roll out and pull up, I held on for dear life. That was a big mistake.

It leveled out and flew into the tree line at max speed followed by a resounding crash sound. It broke everything- everything. The single biggest piece was the glassed center section planking. Not the center section, just the gutted wood and glass planking. Radio destroyed, wheels broke and the engine embedded in a tree trunk. It even folded the "as advertised" unbendable and unbreakable Hallco landing gear. It was spectacular. If you push the limit, things happen - some bad.
Aug 27, 2017, 09:36 AM
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I really enjoy flying my RCM Advanced Trainer (and to be honest, I don't see much difference between the RCM Trainer and the Advanced Trainer, other than the name.) It is a nice, stable platform, with decent aerobatic abilities - at least for my flying skills!

I am happy about my decision to add additional throw on the ailerons, which cured the sluggish roll rate, and added the flaps to help slow things down for landing. The flaps especially make a huge difference. I'm going to be incorporating flaps into my build of the Avenger, which I hope to be able to start building over the winter.
Aug 27, 2017, 09:56 AM
What could possibly go wrong?
Thread OP
I added extra aileron throw too, for exactly the same reason. You've seen that video, you can hear the instructor say the roll rate was sluggish. I just attached the aileron clevises one notch closer to the pivot and I'm much happier with it. I would like to have flaps, I'll do something about it one day. I'm half considering making a new wing, this one has 6" additional span so I might make one the original 58" and with real flaps, one day. But it wouldn't be very hard to add 2 more servos and flaps the same way as the ailerons operate on this one either. Many thanks for the idea regarding the steering linkage, the epoxy is curing now connecting a shaft to my new spring-loaded fitting, copied direct from yours. I even ended up using biro springs just like you said Yes it's truly a fun model, but stable enough to learn with, a good balance of features. It's also proven rugged enough to handle some abuse and always fly another day. Best of luck with yours too.
Aug 27, 2017, 09:59 AM
What could possibly go wrong?
Thread OP
Quote:
Originally Posted by GRW3
...I built a second RCM Trainer 40 with modifications. I made it a tail dragger and eliminated the dihedral. Now since it's a high wing it still has some effective dihedral but it was way better suited for aerobatics.....
That could make this model a lot of fun. It's basically nimble enough, but I do wish sometimes it wouldn't roll on rudder, or turn on roll, thanks to that dihedral wing. That's about all that makes it a trainer, it's more of a high wing sports model IMO now. If I do build that 2nd wing I will consider making it flat, and with flaps.
Aug 28, 2017, 11:03 AM
What could possibly go wrong?
Thread OP
Quote:
Originally Posted by StayQuiet
I really enjoy flying my RCM Advanced Trainer (and to be honest, I don't see much difference between the RCM Trainer and the Advanced Trainer, other than the name.) It is a nice, stable platform, with decent aerobatic abilities - at least for my flying skills!

I am happy about my decision to add additional throw on the ailerons, which cured the sluggish roll rate, and added the flaps to help slow things down for landing. The flaps especially make a huge difference. I'm going to be incorporating flaps into my build of the Avenger, which I hope to be able to start building over the winter.
I'm interested in those flaps you added, in particular the dimensions. Did you just split the ailerons into sections, to make ailerons and flaps, and keep the original chord, or did you modify them? I was just thinking that if the flaps were about 1/3 the span and the same chord as the original ailerons, that's not a great deal of area. though if they had enough deflection they still should be effective. You say yours are handy for landings though so the dimensions must be right. So, at full flap, how much deflection is that, either in degrees or distance?
Actually there are a few more questions I'd like to ask, if you have time to answer. Did you use separate servos for all your flaps and ailerons, for a 4-servo wing, or another arrangement? Because I was thinking that since dividing the ailerons into 2 originally reduced your roll rate, I could take advantage of a feature of my radio - you can set up a 4-servo wing like that so the flaps move with the ailerons, to effectively restore area, until you want to use them as flaps and then they move separately. If you did that, they have to be able to move up as well as down. You'd also be able to program them for crow or butterfly-type air brakes.
I was considering extending the chord of the ailerons at the root, so they taper towards the tip where they have the original chord, and then dividing them at about 1/3 span into flaps and ailerons. That way the flaps have extra area and the ailerons get back some of the area they lost, but it changes the nature of the wing, especially lowering the aspect ratio.
If I do this, I'd probably build a whole new wing of the original span, as mine has been extended by 6", and I'd reduce or completely eliminate dihedreal. This model with a flat wing, flaps and restored aileron area, plus the air-brake function, could be very interesting!
Lastly, what about for takeoff, does adding flaps give you a shorter takeoff run? Or are they more like just air brakes when you land? Thus allowing you to keep up some throttle without gaining too much airspeed.
By the way have you guys seen these? https://outerzone.co.uk/plan_details.asp?ID=6558 It's the RCM Floats specifically designed for the RCM Trainer 58" span versions (the Trainer 60, and I think that also means RCM Trainer and RCM Advanced Trainer... they're basically re-prints AFAIK), and especially designed to be fitted to existing finished models with a minimum of modification. One day I'd love to try it off the river near my place.


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