Official Dynam 1500mm B-26 Marauder Thread

[Hardway]

My B-26 Marauder....

Nice job and welcome to Hobby Squawk!!!! :Cool:

[F4ucorsair]

thanks guys,will put all that into practice .. snap rolls not just yet

[Builda]

Yes, much easier to read. Thanks. I believe the weights were put there (and sometimes, one or both are loose and just rattle around back there), to aid in balancing with the recommended battery and also to reduce the amount of UP elevator for it to fly level. Some have observed that the angle of incidence of the horizontal tail surface is incorrect and needs to be shimmed or re-positioned, thereby needing some UP. If not for those weights, it would need lots of UP, which many find disconcerting. The plane flies fine once trimmed out properly even with some UP elevator dialed in. I fly with a 4000mah battery pushed as far back as it will go and I still need a bit of UP and my weights are still in there. When it's back there, it's hard to do up the strap. If you fly with a lighter battery, it might be better for balance but then, your flight time will decrease. You'd have to experiment with it to find what works for you.
PS, You should do a range test (or two or three) with the plane in different orientations before taking it up.

I'm glad you cleared up the tail weight issue-nothing worse than misinformation in these forums! The way I see it these companies spend thousands in dollars and manhours doing R&D and testing on these models, so when I see people in forums saying "Remove this, change that" I'm very dubious and especially cautious. I like this forum because it's nowhere near as bad as RCG for misinformation and "half a story". I'd been wondering about the weights in the tail as one of mine had fallen out in transit, so I was going to initially fly it with one weight and see what happens-after reading this I'll slap the weight that came out back in the tail end of the fuse.

[xviper]

I'm glad you cleared up the tail weight issue-nothing worse than misinformation in these forums! The way I see it these companies spend thousands in dollars and manhours doing R&D and testing on these models, so when I see people in forums saying "Remove this, change that" I'm very dubious and especially cautious. I like this forum because it's nowhere near as bad as RCG for misinformation and "half a story". I'd been wondering about the weights in the tail as one of mine had fallen out in transit, so I was going to initially fly it with one weight and see what happens-after reading this I'll slap the weight that came out back in the tail end of the fuse.

It will fly fine with one or both or without either of the weights. You just need more UP elevator without them. The worst one for requiring UP ELE is my old LX 70mm A-10. It needed a LOT of UP, but it flew OK (for an LX model). Even today's premiere A-10 (Freewing) requires a wee bit of UP to fly right. Sometimes, when transposing specs from the real thing to a flying model, something just doesn't work the same way and some compensatory mod is required.

[themudduck]

:Thinking: Guys really? Misinformation? After 1600 posts here, now we're saying "oh the plane must be fine since it was carefully designed by experts and we should leave the weights in there"? These Dynam planes have SO many problems and now we're saying that they must be our fault?

Look, I like this plane and I think it was designed well. (It sure wasn't built well). But the recommended battery is too heavy, so the simple factory solution was to add tail weight.
Using a lighter battery means you can ditch the weights and balance it perfectly! What's wrong with that?

Adding weight to the tail is shameful. It literally means "something is wrong and so we need to ADD WEIGHT to fix it."
This is not the hallmark of excellent design.

So... what happens if you take out the tail weights? Its way nose heavy! Solution: use a lighter battery!

But it STILL wants to fly with up trim. With a couple of years and thousands of posts behind us, we've already proven that you can shim the TW of the stab up a few mm and the plane flies great that way, without any up trim and without the tail weights. Now you can certainly fly it "Stock" with the weights and a big-ass battery if you like! But there's nothing wrong with making a plane lighter and helping it fly better. MO, 2 cents, etc.

[F4ucorsair]

its all new information 4 me,, i no the dynam planes r cheaply made , but they r cheaper to buy ..here in auss i paid $450 4 an e flight 1200 f4u.. and then $225 4 a dynam f4u ,, from a local hobby shop 2 miles from me,,,, so as a begginer great value, when u r still crashing them... no buddy box 4 me..just crashed till i could fly..motian rc makes the point ,,2 price points,,,, perfect.. i WILL own a flightline 1600 f4u as soon as humanly possible ... thanx 4 all the great info.. one last thing my first plane was an horizon cessna trainer..i imagined id have a bit of fun ..... now im hooked .. great fun ,,i have about 8 cya

[Builda]

:Thinking: Guys really? Misinformation? After 1600 posts here, now we're saying "oh the plane must be fine since it was carefully designed by experts and we should leave the weights in there"? These Dynam planes have SO many problems and now we're saying that they must be our fault?

Look, I like this plane and I think it was designed well. (It sure wasn't built well). But the recommended battery is too heavy, so the simple factory solution was to add tail weight.
Using a lighter battery means you can ditch the weights and balance it perfectly! What's wrong with that?

Adding weight to the tail is shameful. It literally means "something is wrong and so we need to ADD WEIGHT to fix it."
This is not the hallmark of excellent design.

So... what happens if you take out the tail weights? Its way nose heavy! Solution: use a lighter battery!

But it STILL wants to fly with up trim. With a couple of years and thousands of posts behind us, we've already proven that you can shim the TW of the stab up a few mm and the plane flies great that way, without any up trim and without the tail weights. Now you can certainly fly it "Stock" with the weights and a big-ass battery if you like! But there's nothing wrong with making a plane lighter and helping it fly better. MO, 2 cents, etc.

The last time I followed the advice of ANYONE on RCG it ended with the motor mount board severely melted And if I had continued to fly it would have ended with a fire. One of these "forum experts" was saying to use a certain motor in my Dynam Hellcat as a power upgrade etc etc and he had done it etc etc...I flew it for about 3 mins at half power with his recommended upgrade motor in before the plane started acting odd-when I landed it the motor was so hot it had melted the motor mount, popcorned all the EPO around the motor, and melted the prop to the alloy prop adapter. When I eventually got it all off the plane and set the rig up on a friends thrust bench the motor was something like 600W over its max rating-600W that was released as heat, doing some pretty serious damage to my plane. Ever since that day I've ignored anything like that kind of "helpful advice" unless it's come from a reputable source (Rich baker aka rcinfomer for example). Something I've noticed in these forums Is that a number of people will complain about weak landing gear or other issues, but they conveniently forget to tell people they used a bigger than recommended battery and that their idea of a "greased landing" is more akin to slamming it down on the wheels the right way up.

Thats why why I say "misinformation"

thankfully this forum is nowhere near as bad as RCG for people with "misinformation". As far as weight in the tail goes I agree NORMALLY it's a big NoNo-in fact any ballast on an airframe is something you don't want, but the truth is that it can be easier to tune the CG by having a "default" location for a lipo (which ideally in itself is weight spread either side of the CG) and add ballast to correct it than to make multiple changes to moulds at great expense to try and get the lipo location perfect and not need ballast-then you have the fact that no 2 lipos weigh the same to think about, so designers have to work off "general ideas" of theoretical lipo weight etc. I look at my B26 and if the incidence angle was indeed that bad it needed 3mm added to either fwd or aft of the Hori stab it would stand out like dogs balls-mine looks to be spot on level in relation to the wings and fuse. I'm not 100% clear on what everyone means when they say "up elevator" so I can't comment further on that. In my mind you give it "up elevator" if it's nose heavy (up meaning point the nose of the plane up)-in this scenario the tail weights would in effect be added to cancel that FwdCG condition out (possibly caused by incorrect lipo location). However some people say "up elevator" and mean it in the context that it raises the tail and pushes the nose down, which would give people reason to believe the weight in the tail is too much as it obviously presents the plane has an "aft CG" condition-in this case though reduced aileron authority would instantly backup that the plane is tail heavy with the weights in.

End of the day I just want to fly my damn plane without issues So in closing I guess the real question should be "who has actually taken the time to put this plane on a CG machine, and also setup an Incidence meter on it to see what the REAL issue is"?? Making hypothetical guesses can cost people their models. I will sit it in my Great planes CG machine to see how it stacks up initially, but I don't have an incidence angle meter so I'm not going to trust any advice in here to "shim the hori stab" as experience tells me I know better than to follow such advice. i dont profess to know everything and I'm not "having a go" at anyone, I'm merely stating that in my experience of these forums (and also my decades as an engineer, with a number of years in aeronautical engineering), people that post "advice" in these forums do need to be taken with a pinch of salt because often we only get half the story.

[xviper]

"UP" elevator (aka "reflex") is a situation where the elevator needs to be artificially set (manually or by trim) so that it's like holding your elevator stick to "normally" make the plane climb. However, on certain planes (like this one and the LX A-10), when the elevator was set up to look like it was perfectly level with the tail surface, the plane would slowly dive when you take the hands off the sticks in flight. Planes like these somehow didn't convert well from the full scale to the model and even though the tail surface looked perfectly level, it doesn't act that way. To combat the slow dive (hands off), it needed something. Dynam decided it needed the weights in the rear, but that wasn't enough. It still needed some "reflex" set in. Some don't like having the weight added to the back, so they took them out and this required either to set more reflex or to shim the whole horizontal tail surface entirely to produce that reflex while keeping the elevator inline with the h. stab. Sure, the better way would be to move the battery around, but on some planes, that is not possible without modifying the battery compartment. On this B-26, the battery is as far back as it will go. Gouging out foam to move it further back would mean not being able to access it easily or getting into areas that needs the foam for structural support.
As for balancing on a CG machine, I have one but have stopped using it a long time ago, preferring to just do it on my fingers at measured points on the wings. This is because the published CG for any model plane is only a recommendation. What the final CG is determined by the end user from how the plane flies and how the user flies the plane. I've got planes (have had over 150 of them) that can be flown quite well with CG ranges varying 10 to 20mm. When I started this hobby only about 8 or 9 years ago, lots of people would preach up and down that CG MUST be to the mm and veering off from the posted CG will not end well. I don't see a lot of people spewing off at the mouth about that anymore. In this hobby, you do what is necessary and what is best for you when it comes to making a plane fly well.
As for RCG, well, that's RCG for you. There, you get a lot of "armchair" aeronautical engineers who think their "real" plane background makes them experts in flying models planes. That is not always the case, especially when they only just started flying models. Then there are those who just started with models and after that first decent landing, they suddenly become "all knowing". It reminds me of the movie "Flight of the Phoenix". In that movie, it was the other way around. It was the model guy who translated his knowledge to make a real plane. Of course, in the movie, he made it work, but in real life, would it have? RCG has had a tendency to make the sanest grown man become completely brain dead and it accentuates their ignorance. Lately, I've seen a guy post up statements about how certain things in this hobby are "normal" and not normal. Then we discover that he comes from a background of flying real planes but in this hobby, he's still a beginner. He makes a lot of mistakes when he flies models as witnessed by his videos and his understanding of models is so hampered by his "expertise" for real aircraft, that he's almost always got his foot in his mouth. When confronted with proof of his incorrect thinking, at least he admits it, YET, he continues to spew out facts that are so left field as to be comical. It's up to the intelligent reader, regardless of being a beginner or expert RC pilot, to sift out the garbage. At RCG, there seems to be more garbage than anything. Fools have a much bigger audience to perform for over there and perform they do.

[F4ucorsair]

id also say, most fly rc 4 different reasons.. some like to be technical,, some just wana fly ,, cause its fuuuuun.. many r warbird freaks,, and some just 4 freindship...theirin lies a large variety of opinions etc.... back to the b26,in real terms these r just big boys toys,, if they were all rolls royce aircraft quality,, we would own 3 or 4 maybe .. i would rather own heaps ,, and modify to our desire .... ps those 850 mm mustangs look fun,, do rc guys use ribbon , and dogfight ?? HAPPY FLYING

[xviper]

id also say, most fly rc 4 different reasons.. some like to be technical,, some just wana fly ,, cause its fuuuuun.. many r warbird freaks,, and some just 4 freindship...theirin lies a large variety of opinions etc.... back to the b26,in real terms these r just big boys toys,, if they were all rolls royce aircraft quality,, we would own 3 or 4 maybe .. i would rather own heaps ,, and modify to our desire .... ps those 850 mm mustangs look fun,, do rc guys use ribbon , and dogfight ?? HAPPY FLYING

I prefer "heaps" myself. Most RC clubs have "combat" competitions. They sell specific planes for dogfighting where they try to cut each other's ribbons but people have used all manner of planes to do this, not just dogfighters.

[Builda]

id also say, most fly rc 4 different reasons.. some like to be technical,, some just wana fly ,, cause its fuuuuun.. many r warbird freaks,, and some just 4 freindship...theirin lies a large variety of opinions etc.... back to the b26,in real terms these r just big boys toys,, if they were all rolls royce aircraft quality,, we would own 3 or 4 maybe .. i would rather own heaps ,, and modify to our desire .... ps those 850 mm mustangs look fun,, do rc guys use ribbon , and dogfight ?? HAPPY FLYING

I just fly because I enjoy the "brain time" (if that makes sense). I don't get a kick out of making my plane "look" like a "scale rendition" with airbrushed oil smears etc as for me it's about what they look like in the air and you can't see any of that when it's flying as you know-in fact I usually try to keep them looking as pristine as possible. As for friendship, I also enjoy a bit of that too flying with my Dodgy mate here who has a YouTube channel or two lol. We do the combat thing too with ribbons on occasion, either that or Bruce will drop a toilet roll from up high and we all try to chop it up as much as possible.

And yes Xviper, your spot on with these "armchair aeronautical engineers" on RCG lol. When I had the Hellcat incident I was still somewhat a beginner of sorts with RC planes and hadn't modded anything at that point-unlike now where I have a thrust bench of my own and I usually do all the sums etc before I go swapping motors on a plane for more power. I can't stand that forum, so many "experts in their own minds" on that forum, not to mention the incessant bloat posts in each thread! With this B26 I'll just put the second weight back in that had fallen out and go from there-chances are I'll probably end up selling my B26 after all this anyway to make room for other planes, but you never know-if it flies nice I'll keep it.

[boomer108]

I just fly because I enjoy the "brain time" (if that makes sense). I don't get a kick out of making my plane "look" like a "scale rendition" with airbrushed oil smears etc as for me it's about what they look like in the air and you can't see any of that when it's flying as you know-in fact I usually try to keep them looking as pristine as possible. As for friendship, I also enjoy a bit of that too flying with my Dodgy mate here who has a YouTube channel or two lol. We do the combat thing too with ribbons on occasion, either that or Bruce will drop a toilet roll from up high and we all try to chop it up as much as possible.

And yes Xviper, your spot on with these "armchair aeronautical engineers" on RCG lol. When I had the Hellcat incident I was still somewhat a beginner of sorts with RC planes and hadn't modded anything at that point-unlike now where I have a thrust bench of my own and I usually do all the sums etc before I go swapping motors on a plane for more power. I can't stand that forum, so many "experts in their own minds" on that forum, not to mention the incessant bloat posts in each thread! With this B26 I'll just put the second weight back in that had fallen out and go from there-chances are I'll probably end up selling my B26 after all this anyway to make room for other planes, but you never know-if it flies nice I'll keep it.

Hey Builda, the way I see it is whatever makes you enjoy the hobby is what you should do and the friendships we establish in the hobby are great also. And by the way nice pair of beavers.LOL

[F4ucorsair]

hey builda how r u.. seen u on u tube many times...... not sure of the lowest voltage per cell before u kill the lipo??.. hope u can help thanx,, maybe better question is recommended lowest per cell??

[Builda]

hey builda how r u.. seen u on u tube many times...... not sure of the lowest voltage per cell before u kill the lipo??.. hope u can help thanx,, maybe better question is recommended lowest per cell??

Hi mate, I'm no pro but I generally don't run my lipos below 3.8V/cell. Way I keep track is I run a lipo in each of my planes at WOT Anchored down, then keep track of the cell voltage vs time-nothing overly complicated! Then I set a timer for each plane so I know when the timer goes off on my Tx I need to look at landing-pretty simple really. I've got a few lipos still that are 3 years old and their cell resistance shows about 10 milliohms/cell so my lipo care must be on point I guess. FYI too I always fly sitting down due to my poor health (I can't stand up for very long or walk very far-it means I always set up next to the runway too whereas most of the guys set up outside the hangar). Next summer I may start to take my mobility scooter down so I can be more sociable with the guys over at the hangar.

I have a YouTube channel too which has a few videos from tokoroa on it: https://www.youtube.com/channel/UCLx...BR-fLrwZZ5jtHQ

[BOSSman760]

how come after connecting my flysky radio and receiver, the props are spinning same direction not counter rotational? i tried reversing one of the wires on one motor but the receiver loses power when i connect like that

[xviper]

What do you mean you "reversed one wire"? Each motor has 3 wires going to it from the ESC. To reverse the motor direction, you need to swap TWO of those wires. Unplug any two and plug them back into the other.

[Ah's Availble]

Hi All,

New to this site. I just built and flew my Dynam B-26. It took off fine, but pulled hard to port requiring full aileron trim and some rudder trim to get it stable. Then I had to crank in the aforementioned elevator trim. to get the nose level. Once I did that I found the plant to fly sluggishly at anything less than 3/4 throttle. My guess is that the deflection on the aileron and elevator was providing a lot of drag.

When I throttled down to try an approach I was greeted with a tip stall and almost lost her. Fortunately I was at least two mistakes high.... Then I was a little shaky and forgot to drop the flaps and made a hot landing, losing a prop to the grass when I went off the end of the runway.

My CG is currently at 60mm with the tail weights still in. I think I will try to put in the elevator shim to correct for the down trim. However, has anyone had the experience with the roll issue? I have 2mm of aileron in each side to correct.

[xviper]

Interesting that you posted today about this plane. I flew mine this morning for the first time this year. I've had it for a couple of years. Mine has both weights in the tail and all retracts have been replaced by left over retracts from other planes that I had laying around. The original retracts were problematic whenever the temperatures outside got below about 60F. I just checked my trims for today's flight and the AIL trim is almost dead center. The ELE trim is actually quite a bit DOWN. I guess if I took out the weights, it would be more neutral, but it's been flying quite well for me for 2 years, so I'm not changing anything. Rudder is slightly off center for better ground tracking. This plane (IMO) is a bit underpowered and should be flown at high throttle most of the time. I fly mine at 3/4 to full throttle the whole flight. Below that, the plane goes too slow in turns and drops a wing badly and stalls. Keep the throttle high and it will fly just fine. It has been noted that the wing doesn't sit flush at the saddle. You can see this in my video when the plane is on the ground. Some guys have shaved foam to make it flush, but mine flies fine, so I didn't bother. Dynam is an "economy" brand and I expect some flaws.

Here is the flight from a couple of years ago:

I wasn't going to post this video as it's "old news". I took it just for my own records. This morning's flight was in very strong winds and high wind gusts. I should not have used 1/2 flaps for take off in such high winds as the wind nearly flipped it over as it took off. Other than that, it has no adverse roll tendency.

[quitcherbitchen]

Try syncing the throttle. Plug in with full throttle( props off ) and once it beeps pull down to off.

[TiredIronGRB]

Try syncing the throttle. Plug in with full throttle( props off ) and once it beeps pull down to off.

Beeps twice :)