Official Black Horse 1724mm Dornier DO335 Pfeil ("Arrow") Thread

[MrSmoothie]

Thanks for sharing the vid. It didn't seem to be lacking for power on 4S. Interesting that he had to push the two 4S 4000 lipos all the way forward and still had to add 100g of lead to the nose.

I agree, it did not seem to be lacking. Not that I'm advocating for 4s -- still plan to go 6s. However, my aforementioned VQ A-26 is powered with 4s, using the "upgrade" motors MRC sells for the FW P-38, and it really scoots.

I was also interested in what he had to say about CG -- and am awaiting OXO's experience since he's using what I'm guessing is a heavier motor on the tail end than our Aussie friend. Given the moment arm, it could take a lot of lipo or lead to counter. This was partly why I asked in my earlier post about using a potentially smaller motor aft, and if you can run two dissimilar motors from the same lipo.

[Oxotnik]

Yeah, I've been a bit worried about the 5055 on the rear of the 335. I hope that I don't have to add a ton of nose weight.

I use the Chief Aircraft multi-servo connectors on my 91" Phoenix Model, as I do remove its wings for storage and transportation. The multi-servo connectors at the wing interface make attachment of the wings quite easy.

[downwind3zero]

Yeah, I've been a bit worried about the 5055 on the rear of the 335. I hope that I don't have to add a ton of nose weight.

I use the Chief Aircraft multi-servo connectors on my 91" Phoenix Model, as I do remove its wings for storage and transportation. The multi-servo connectors at the wing interface make attachment of the wings quite easy.

I'm thinking of using a Tru-Turn in the front and a light weight spinner in the rear for hat reason, also using the 5055's.

[OV10]

Lets blow the whistle on the nervous nelly concerns about CG and the rear motor weight affecting it based on a vid that didn't have any detail other than it was flown on 2 4S 4000.
Lets assume that it had the standard 42xx 4S capable motor driving a 14" MAS prop.
Those motors weigh approx. 8 oz versus the Spitty 5055 motor @ 14.5 oz.
So you are six ounces heavier (both rear and front) but the medium distance of rear/front moment arm is like a 55/45 distance from CG on the fuse X axis.

The counter balance to the rear motor weight offset which is gonna be minimal will be done with the heavier 6S LiPo's.
An average 4S 4000 weighs approx 13.5 oz and the 6S 4000 @ 20 oz.
So you have an increase of 13 oz for two 6S in the nose to off set any differential in the tail.
If you need more weight???? then it looks like a 5000 (25oz) will fit which adds another 10oz to the total to offset with.
Chuck - Your not gonna have to add any dead weight as if you are powering up a short nosed radial warbird.

[Oxotnik]

Only one 6S-5AH battery will fit in the battery bay. I'm wishing that I could fit two 6S-5AH batts in the bay. I should probably be looking for a significantly larger capacity battery.

[Creative RC]

Mine arrived as well and luckily there was no damage to the tail but can easily see why that can happen. I agree Mr. Smoothie, I hope the covering will be easily accept paint but maybe the wall paper like finish will grow on me after a while. Is this a plastic film with paint on it or a painted paper type covering? Maybe add some saffron yellow or red to it and not red spinners. I tried the link from the 4s application video but no luck. I would like to know what motors etc. he used. I am thinking he went that route, 4s and 8000 mah, to improve flight time, preferring scale flight over speed. Like you Oxo, I am wondering whether a second 5000 6s battery could be added, maybe by making the canopy/pilot area a removable hatch and getting a second battery in over the wing? Not yet sure what the complications would be to try that. The model seems big enough to carry a second one, but as you say a battery larger than 5000 seems needed. It is my first twin which will be a learning experience. I am toying with the idea of using a lighter FMS predator 4258 550 kv motors which can run up to 1400 watts on 5-6s (only because I already have one on the shelf). That is one long power lead to the back. Is it possible to have two separate power systems and receivers? I am still early in my ideas for this plane and eager to learn more about that 4s setup and how things go with Oxo’s well advanced production with his 5055 setup. It will no doubt be powerful and quick.

[Twowingtj]

Here's the direct link to the Aussie guy's set-up...

I'm leaning toward 6S myself.

[Oxotnik]

Mine arrived as well and luckily there was no damage to the tail but can easily see why that can happen. I agree Mr. Smoothie, I hope the covering will be easily accept paint but maybe the wall paper like finish will grow on me after a while. Is this a plastic film with paint on it or a painted paper type covering? Maybe add some saffron yellow or red to it and not red spinners. I tried the link from the 4s application video but no luck. I would like to know what motors etc. he used. I am thinking he went that route, 4s and 8000 mah, to improve flight time, preferring scale flight over speed. Like you Oxo, I am wondering whether a second 5000 6s battery could be added, maybe by making the canopy/pilot area a removable hatch and getting a second battery in over the wing? Not yet sure what the complications would be to try that. The model seems big enough to carry a second one, but as you say a battery larger than 5000 seems needed. It is my first twin which will be a learning experience. I am toying with the idea of using a lighter FMS predator 4258 550 kv motors which can run up to 1400 watts on 5-6s (only because I already have one on the shelf). That is one long power lead to the back. Is it possible to have two separate power systems and receivers? I am still early in my ideas for this plane and eager to learn more about that 4s setup and how things go with Oxo’s well advanced production with his 5055 setup. It will no doubt be powerful and quick.

Higher kv with the smaller smaller motor (compared to a 5055-390, 60-size motor) should do pretty well. My guess, without having any data. What size props are you thinking about using?

I'm starting to think about downgrading my prop from MAS 16x10x3 to MAS 15x9x3, because the 15x9x3 will work better with the spinners that I already have. I need to put the motor and props on a wattmeter, to help me make a more informed decision about which way I should go with the prop. I'm actually concerned that the 5055-390kv and 15x9 will not provide the wattage needed for a strong enough power train.

[OV10]

Here's the direct link to the Aussie guy's set-up...

I'm leaning toward 6S myself.

Thanx for mining that info TJ. The details of his setup confirmed my assumptions that I made in post #124.
I truly believe 6S is gonna be the way to go especially if going with a more scale diameter 3 blade prop of 16".
The 6S power from the FMS 4258-550kV (Olympus/Beaver) or the FMS 4258-460kV(Tigercat/P-47) will serve those well in using 14-15" props, 550kV for 15" 2 blade and 460kV for 14" 3 blade.

[MrSmoothie]

Lets blow the whistle on the nervous nelly concerns about CG and the rear motor weight affecting it based on a vid that didn't have any detail other than it was flown on 2 4S 4000.

I see that somebody else added the direct link with all the specifics about that 4s setup. I believe he also added 100 gm of nose weight, if I'm not mistaken.

Oxo, why only a 5000mAh lipo? Is that just what you happen to have? I know a 6000 HRB will fit, and I just haven't bothered to try a Roaring Top 6250, but I don't think it's much different than the 6000 HRB. I don't own any 7000's but would probably look into this (to see if one will even fit) after some successful flights.

I have little doubt that I can repaint this material, although obviously I haven't tried. My most recent project (a total rebuild of the old CY Models 61" ME-163 Komet) included painting the iron-on covered wing panels and this was a total success -- I've had zero issues with adhesion. I realize this isn't the same as the Do335's material, but I'm confident that the iron-on covering is more of a challenge than what's on the Do335.

[Creative RC]

Oxo, since you are more advanced in the build could you comment on the possibility of installing a second 5000 mah 5s or 6s battery below the canopy area or front of the wing area or even directly over the main wing spar. My thought is to make a hatch out of the canopy/cockpit materials and put in a battery floor directly below it and extending past the main spar tube if possible. Maybe the battery floor would have to be at an angle and even intrude somewhat under the canopy.

To add a battery floor, the former has a brace which might have to be lowered and the former itself reinforced overall. Depending on CG and if there is room, the battery could even extend over the wing spar a certain amount. Are there any obstructions, either mechanical or electrical which are installed which would prevent this modification? Would the retracted wheel be in the way of lowering the former brace? To avoid obstructions, the battery could be even angled at say 45 degrees such that one end of the battery enters the cockpit area. Would you have a photo of the area under the canopy to see what you have installed in there?

Attached are some photos. I am looking at fly it both 5s and 6s and having battery location options will be useful. The first photo shows two 5000 5s fitting together in the battery compartment. The other photos could be either 5s or 6s configurations. The last is the former brace that is in the way.

Also, glad to read the cover will be easily paintable as I would like to add either red or yellow, even the green heart as in the previous photos.

Thank you,

Francois
20200316_114026.jpg

[Oxotnik]

Nick, 6S-5300mah is the largest 6S that I have. I'd prefer to NOT have to buy a bigger 6S battery for this aircraft, but I will if it's needed. I'm waaaaaaay too deep into this project to cheap-out now. LOL

Creative, It's a very interesting idea to put a 6S battery below the cockpit. There's not much structure down there, but it should easy enough to add a little more structure and a battery sled which would better support a 6S battery. I think that there's enough clearance under the cockpit for a 6S battery. To the best of my knowledge, there's nothing below the cockpit that'd interfere with cable runs. You can slide the plastic nose gear wheel well into place, to get an idea of how much space the NG will take up. It's not bad though. Right now, I have a full figure 1/7 - 1/8 pilot sitting in the cockpit, with his feet dangling down below the cockpit, and his feet aren't close to interfering with the nose gear. I'm going to look into this some more. I'd REALLY like to have two 6S-5AH batts driving the two 5055 motors.

[MANFRED]

Just get a 7000mh 6s, should probably get 6 to 8 min elite time depending on how hard you push it

[MrSmoothie]

Hey OXO, not for nothin', but...

I had this thought balloon -- what other ARF twins are out there of comparable size and what motors/props are guys having success with. The Phoenix A-26 Invader came to mind. Looking at the RCG thread, I was reminded that you are flying one, and your motors are Aerodrive SK3 5055-430kv with MAS 14x8x3 props. I don't know what your A-26 flying weight is, but by most accounts its a few pounds more than the reported flying weight of the Do-335. Listed specs are 13.2 lb for the Do-335 and 15.5-17.5 for the A-25.

But here's the kicker -- would you believe that the Phoenix A-26 has EXACTLY the same (listed) wing area as the Black Horse Do-335? 61.4 dm2 or 952 sqr. in.

[Oxotnik]

Creative, I just walked upstairs and looked at my 335, with the thought of adding a 6S battery under the cockpit. With the NG retracted, I don't think that there's room under the cockpit, between the nose wheel and the wing spar. The only viable option for a battery in that area would be to completely remove the cockpit, in my opinion. I"m not willing to do that for mine (especially after hiring a WarbirdPilots Luftwaffe pilot to drive this 335). Another option that I think is viable would be to add a battery platform above the servos in the servo back. I set a 56S-5AH battery in there and didn't see any problems with real estate. The downside to that approach is that the battery would be behind the CG, which could raise a weight/CG concern. Probably, if deciding on a 6S power train, a large-capacity 6S battery in the battery bay would be the best option.

Nick, I started out thinking about using the same exact power train that I'm running in my 91", 17-lb Phoenix A-26 (dual Aerodrive Sk3 5055-430kv, MAS 14x8x3 props). The Do-335 is lighter and more streamlined, with lower wing loading and lower wing cube loading. That power train was generating 1100W/motor, for 2200W total, and only pulled about 60A max (static). This power train was very nice in my A-26. The Flightline Spit 's5055-390 motor has a slightly lower kv and they're swinging a 16x10x4 prop on the Spitty. I'd like to swing MAS 16x10x3 props with them, for scale, but I am thinking about dropping back to 15x9x3 props. If HK had the Aerodrive SK3 5055-430s in stock, I would've gone that route again. The Spitty 5055s were my second choice.

[Oxotnik]

Just get a 7000mh 6s, should probably get 6 to 8 min elite time depending on how hard you push it

I agree that I'm probably going the route of a larger 6S battery. There's certainly room for it in the battery bay. I'd prefer to not have to buy a larger battery (6S-5AH has been a sweat spot for me, as I have 8 or planes that use that size battery), but I will if needed. I can live with EDFs having only 3 1/2 minutes of flight time, but I'd like for my prop planes to get 5 minutes, easy, of flight time.

[Oxotnik]

Just for grins, I just put the Flightline Corsair's 18" 3-blader on the 335's pusher motor shaft, and the ventral fin is still an inch or two lower than the prop blade. So, the FlightLine Corsair's power train would be really interesting back there.

[Twowingtj]

I might be looking at running a 6S 7000mah battery in the DO as that looks like what I'll be going with(x2 for 12S) in the Black Horse Gilmore,

[MrSmoothie]

The Flightline Spit 's5055-390 motor has a slightly lower kv and they're swinging a 16x10x4 prop on the Spitty. I'd like to swing MAS 16x10x3 props with them, for scale, but I am thinking about dropping back to 15x9x3 props. If HK had the Aerodrive SK3 5055-430s in stock, I would've gone that route again. The Spitty 5055s were my second choice.

If the Spit uses 16x10x4 -- dropping to a 3-blade, would you not have to increase the diameter (or increase the pitch, if that's even possible)? I see the lower kv Corsair motor (340 vs 390 for Spit) uses 18x12x3.

Going by what looked like a decent scale drawing, I came up with 17" diameter for the nose and 16" for the tail. If things worked out, it would be cool (for a change) to have scale diameter props.

[OV10]

If the Spit uses 16x10x4 -- dropping to a 3-blade, would you not have to increase the diameter (or increase the pitch, if that's even possible)? I see the lower kv Corsair motor (340 vs 390 for Spit) uses 18x12x3.

Going by what looked like a decent scale drawing, I came up with 17" diameter for the nose and 16" for the tail. If things worked out, it would be cool (for a change) to have scale diameter props.

1st Q/A Dropping the prop from 4 to 3 blades is going to reduce the load on the motor whereas all the exponential power factors will follow.
There is no requirement to maintain the same equal load of the stock design but there is a requirement not to exceed the maximum rated power.
(ie…….putting the Corsair prop on the Spitty motor, that's why the difference in kV's)
2nd Q/A MAS does not make any 3 bladed props larger than 16inch. I even requested a special larger make from them 2 yrs ago and they don't do that.