Official Dynam 1500mm B-26 Marauder Thread

[rifleman_btx]

Wow my 4000 without the weights is just about to the forward end of the mount ramp. Very strange indeed, while my 5000 is pushed back around 2in farther aft the cg is set to 65mm on the button

[xviper]

I suppose what brand of 4000's you have might make a difference. The ones I've been using in my B-26 are Gravity brand that weigh 428g. My Admirals weigh in the high 300's. When I start using those, they'll probably be where yours is.

[themudduck]

I am using a 3600, with no tail weights, and I have a 1-inch chunk of foam behind the battery to keep it from slipping backwards.

I am using the 55-60 point and I find that it flies very well-balanced there (as determined by flight testing for balance).

You can use a bigger battery, and use the tail weights, but you guys are flying a heavier plane at the same balance point. That provides advantages and disadvantages, and consequences.
Heavier planes need more power and penetrate the wind better (higher wing loading). But they crash harder as well.
Personally I've always felt that lighter is better. That's my mantra. Ommmmmmmmmmmmmm

[quitcherbitchen]

Lighter battery as Themmudduck mentioned is the obvious solution. I don't think this plane needs a 4000mah battery. I modded my HSD Zero by taking out all the nose weights adding a Esse sound system and a bigger motor. If flies 10 minutes to 40% on a 3300 4s battery. Super efficient. Normally it would use a 4000 4S as stock. Mine is light and nimble.

[rifleman_btx]

I suppose what brand of 4000's you have might make a difference. The ones I've been using in my B-26 are Gravity brand that weigh 428g. My Admirals weigh in the high 300's. When I start using those, they'll probably be where yours is.

Agreed, I'm just using a standard zippy flightmax. I'm not sure the weight on it, and the 5000s are nanotechs

[Bearcat]

I am using 3600 and 4000 Admirals so I do have them marked inside, I noted that old marks inside and the new ones, the biggest change was the 4000 was moved about 10 mm backwards while the 3600 was moved 5mm forwards and the plane has a slight nose heavy balance and I do mean slight..

[rifleman_btx]

Bingo! There ya go! :)

[quitcherbitchen]

I noticed a few things. One, the horizontal tail has a lot of flex At least mine does. Reinforcing this might be difficult as I would have to make a custom spar. Two, the leading edges of the wing have a lot of mold flash. I sanded this off. Three, the outer wing panels may be able to be warped to put in some washout. Maybe put some shims under the trailing edge and put some weight on it for a few days. All three of these things can maybe tame the tip stall issue.

[rifleman_btx]

I had to add full trim from out of nowhere with mine today, I don't know if I have a warped wing or what but I did max the aileron trim on her today. Other than that she did fly well once she was trimmed. Looped and rolled just fine.

[xviper]

I had to add full trim from out of nowhere with mine today, I don't know if I have a warped wing or what but I did max the aileron trim on her today. Other than that she did fly well once she was trimmed. Looped and rolled just fine.

That's a bit alarming. Check to see if one or both aileron hinges are separating. I had a similar occurrence with my Canadair water bomber last time out. On the second flight, I had to use almost all of my UP elevator. Upon inspection, I noticed that the elevator hinges was pulling out of the control surface. This plane has a left and right elevator that are connected by a wire that holds both sides in sync and only one side has the horn that is connected to the servo. With one side being so sloppy, it needed a lot of UP to average out the other droopy side.

[fhhuber]

Sudden trim change definitely means something broke.

[quitcherbitchen]

Maybe a loose servo in the pocket

[Bearcat]

I am using a 3600, with no tail weights, and I have a 1-inch chunk of foam behind the battery to keep it from slipping backwards.

I am using the 55-60 point and I find that it flies very well-balanced there (as determined by flight testing for balance).

You can use a bigger battery, and use the tail weights, but you guys are flying a heavier plane at the same balance point. That provides advantages and disadvantages, and consequences.
Heavier planes need more power and penetrate the wind better (higher wing loading). But they crash harder as well.
Personally I've always felt that lighter is better. That's my mantra. Ommmmmmmmmmmmmm

I agree- I took out both flew her this way using a 4000 and 3600 Admiral batteries..I do like the 3600 for the speed but wind does affect her some, the 4000 size is no issue at all.

[rifleman_btx]

I'm gonna definitely check into those as possible issues and have checked for a loose servo already. Thanks guys!

[Mad Baron]

I know this might have been brought up already but here goes I took my B-26 to the flying field today but didn't fly it because the retracts were not cooperating. When I plugged in the battery and I waited for the gear to initialize just 2 would work and a several seconds later the 3rd gear initialized before it extended and when retracting it had the same issue. After several cycles of the gear they worked ok but I was worried that the gear would not work in flight. It was in the mid 60s today so I don't think the temperature was to blame. I really don't want to modify another brand of gear into my plane but it might come to that. Any thoughts?

[xviper]

Dynam retracts have always been intermittent. The cooler it gets, the more intermittent. Even in warm temps, they sometimes don't work. Once near freezing, they are more likely to not work at all. Since I replaced mine with retracts from old, dead planes (FMS, Freewing), they work all the time regardless of temperature outside. Yours has proven to be temperamental. I wouldn't trust them even in the summer months. I've done many belly landings because they stopped working when it came time to land.

[rifleman_btx]

Yeah that's why mine now has freewing in it as well

[quitcherbitchen]

Which Freewing? My nose gear only works every third try. Are they direct drop in?

[rifleman_btx]

I posted the extreme surgery I needed to do to make it work in the thread.. it wasn't easy at all unfortunately. In fact it very much sucked as I had to redesign the entire retract body on the nose gear by using the original dynam mount plate.

[quitcherbitchen]

OK then maybe do a board transplant from another retract. Seems the Dynam boards are the problem.