Official Dynam 1500mm B-26 Marauder Thread

[Papy58]

Hi borntoolate,
Did you measure the engine consumption? The original controller of F8F bearcat is a 40A. Papy58

[Papy58]

the B26 propellers are slightly larger (10.5x8x4 for 10x7.5x4).

[borntoolate]

Hi borntoolate,
Did you measure the engine consumption? The original controller of F8F bearcat is a 40A. Papy58

Hi Papy58. I am sorry, I did not. Most, or all, of my motor/esc stuff is farmed out to a buddy who is very knowledgeable in that area. I tell him what I want/have and he recommends a course of action for me. I figured the 60amp ESC's would add a little safety in the mix for me. I just had some new ESC's on hand and I am not overly pleased with Dynam equipment. (retracts, ESC's)

Bob

[borntoolate]

My B-26 had an unfortunate mishap about a month ago. Since I needed to repair the fuselage anyway, I opted to modify the bomb bay to a newer version. Thanks to Quitcherbitchen's advice, I decided to move the rudder and elevator servos further aft. I ended up moving them about 10 inches (254mm) back towards the tail. The allowed me to gut the bomb bay area under the wings. I could have fit 4 or 5 "Adam Bombs" in a free fall (when the doors opened) or 2 "Adam Bombs" with a bomb drop device. I already have a B-17 that will drop 4 or 5 bombs so I went with the toggle device. I am not finished but I took some pics of the progress so far if anyone is interested. I would also like to give credit to Tom Hunt. His bomb bay design for the B-17 inspired me in regards to the toggle device. Thanks Tom and Adam!

Bob

[CFIT rob]

Love the bomb bay bomber bob. Thats my next upgrade. For those new to the b26 and dynam, the fit/finish often requires modification to turn into a more "model scale". Beacon foam filler and a paint job can go a long way in covering up these issues. Mine is totally stock with the only non-cosmetic mod being improving the wing bolt mounts with a little ply. Weights in the tail,elevator 3mm up. It flies great, lands easy,and even at 3/4 throttle i get 9min of safe flight with a few in reserve. (4000ma 30c chinahobby line). Mine is the one of the pre-order first batch. The gear is a problem in cold weather (my third batch p-61 does not have the issue). Its worth the money. Even with the dynam quirks. Finger shows my CG with gear down. Foil is 338012x12 ,6 per pack alum foil tape from amazon.

[borntoolate]

Love the bomb bay bomber bob. Thats my next upgrade. For those new to the b26 and dynam, the fit/finish often requires modification to turn into a more "model scale". Beacon foam filler and a paint job can go a long way in covering up these issues. Mine is totally stock with the only non-cosmetic mod being improving the wing bolt mounts with a little ply. Weights in the tail,elevator 3mm up. It flies great, lands easy,and even at 3/4 throttle i get 9min of safe flight with a few in reserve. (4000ma 30c chinahobby line). Mine is the one of the pre-order first batch. The gear is a problem in cold weather (my third batch p-61 does not have the issue). Its worth the money. Even with the dynam quirks. Finger shows my CG with gear down. Foil is 338012x12 ,6 per pack alum foil tape from amazon.

Thanks, CFIT rob! You are correct - with a little bit of tweaking and some cosmetic work, these Dynam planes can be really nice flyers.

Bob

[Builda]

The 11Hobby motors were nearly a drop-in fit. The stock X mount was a close fit. I did need to slightly open the holes in the X mount - but just slightly. I did change the ESC's to new 60 amp units. I was able to use the stock propellers as well.

Bob

Thanks Bob. I haven't looked at my B26 to see (at the time of writing this), but were you able to swap the ESC's without removing the Nacelles from the center wing section?

[borntoolate]

Thanks Bob. I haven't looked at my B26 to see (at the time of writing this), but were you able to swap the ESC's without removing the Nacelles from the center wing section?

If I remember correctly, I was able to get the ESCs out but we did remove the nacelles to replace the stock ESC's as the 60 amp ESC's had a different gauge wire. It was not really difficult as the nacelles are glued on and with some steady pressure we were able to separate them from the wing section.


Bob

[Phantom]

I currently fly a multi-engine turbo prop STOL aircraft that incorporates aerodynamic/geometric wing twist along with wing fences to ensure a nose first drop wings level stall characteristics. It is almost impossible to have a wingtip stall, short of getting myself into VMCA. Has anyone played with modifying the leading edge of the outer 1/3 of the wings on this bird.... because I am about to start... I thinking of using some extra wing fences from a Delta Ray. Then either add to or change the angle of incidence on the outer one third of the leading edge,... just brainstorming...

[quitcherbitchen]

No one has modded the outer third of the wings as far as I know. Just the tail incidence, which is way off. I don't think the tip/accelerated stall is much of an issue as long as you don't use too much elevator throw. My biggest problem with flying this model is lack of power and wind issues causing it to get really tossed around in crosswinds. I plan on putting a Gyro in mine. Power wise stock is just sufficient. In wind it is barely sufficient. Flying around at full power in a 8 knot breeze is not comfortable.

[Phantom]

I have just completed the removal of the two lead weights in the tail and the 3mm tail incidence mod. Before reading this thread, I was ready to borrow deeper aft into the foam to shift the battery further back, in order to get the aircraft to stop flying "nose heavy", however I am hopeful that the incidence mod on the tail will improve that undesireable characteristic. The only thing worse than flying around in a underpowered model in a stiff breeze, is flying one where your are in the upper 3/4 of your power quadrant and having to keep the speed up and the elevator stick pulled back because you've run out of up elevator trim adjustment on your radio. :( I have experienced the wing tip stall on my second flight right after take off. The first flight was uneventful aside from the rodeo that the elevators sensitivity took me on haha. The second flight she flipped right over on her back before I could think. My take off/ rotation technique is simple and in my personal opinion a tried a true method. I set take off flaps somewhere between 10 and 25 degrees depending on the model, accelerate to full throttle at a moderate pace, and when tracking true I apply a little back pressure on the elevator stick and let the plane decide when to become airborne. I never yank her off the runway. On that second flight she decided to become airborne, and then about 10 feer AGL, at a very modest AOA in the climb, snap rolled inverted. So I am going ahead with the aforementioned mods, and I'll post some pics after there completed with a flight report. :Cool:

[quitcherbitchen]

3mm isn't enough. Try 4 to 5mm

[Phantom]

Really!? Well I basically raised it to meet my programmed up trim after turning on the radio. I have three successful flights on it since programming that up trim, of course as soon as I start to slow down and configure for landing, I have to start pulling back on the stick to maintain level flight so.... I'll try it with the current 3mm. I can always increase it. Thanks for the tip.

[themudduck]

Really!? Well I basically raised it to meet my programmed up trim after turning on the radio. I have three successful flights on it since programming that up trim, of course as soon as I start to slow down and configure for landing, I have to start pulling back on the stick to maintain level flight so.... I'll try it with the current 3mm. I can always increase it. Thanks for the tip.

Hey Phantom, I did what you did (increased the stab incidence about 3mm to match the up trim) - but I am also using a smaller 3600 battery (and no tail weights). Lighter weight means the motors aren't working quite as hard, plus it won't be as nose heavy. You don't need a 4000mah batt in this one.

[Phantom]

Thanks for the info Marc, my last 3 flights were with a 4000mah 4s pack. I've tried 2200 4s all the way to a pair of 2650mah packs in parallel. So I am hoping that I can still use the 4000 4s pack because of having to fly this bird at such a high power setting I'm not getting the flight time I want with a lower mah capacity pack. Hopefully matching the previous up trim on the elevators with the incidence mod will give me level flight, and further more the mods I am making to the leading edge of the outer 1/3 of the wings will allow me to fly at a lower power setting without wingtip stalling. The only other option is repowering her if this mod doesn't yield the desired results.

[Phantom]

Step 1 of mod

[Phantom]

Removed about 6mm tapered down to 3mm at the wingtip, leaving about 2mm of foam depth on the top of the wing to allow bending.

[Phantom]

Creates a "V" incision inti bottom edge of the wing's underside

[Phantom]

The end result is increasing the camber on top of the outer 1/3 of the wing so that in landing attitudes the lift is evenly generated the full length of the wing. More importantly the outer 1/3 of the wing doesn't benefit from the induced lamenent flow of air, what we call "apparent wind" from the props. That portion of the wing's ability to create lift lies solely with your head wind and the aircrafts forward speed.

[Phantom]

At higher AOA it ensures that the 1st 2/3 of the wing stalls before the wing tip, thereby ensuring the preferred nose down stall instead of the wingtip stall. Sorry forgot to add, just add some hot glue and bend and hold the leading edge down for a minute to complete the mod. Wing fences will go on tomorrow.