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

MANFRED · Mar 16, 2020, 11:59 AM

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

Oxotnik · Mar 16, 2020, 11:38 AM

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.

Creative RC · Mar 16, 2020, 10:47 AM

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

Attached Files

MrSmoothie · Mar 16, 2020, 09:43 AM

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.

OV10 · Mar 16, 2020, 08:03 AM

Originally posted by Twowingtj

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.

Oxotnik · Mar 16, 2020, 07:36 AM

Originally posted by 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.

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.

Twowingtj · Mar 16, 2020, 05:57 AM

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

I'm leaning toward 6S myself.

Creative RC · Mar 16, 2020, 04:30 AM

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.

Oxotnik · Mar 15, 2020, 07:30 PM

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.

OV10 · Mar 15, 2020, 06:51 PM

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.

downwind3zero · Mar 15, 2020, 06:16 PM

Originally posted by 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.

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.

Oxotnik · Mar 15, 2020, 05:13 PM

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.

MrSmoothie · Mar 15, 2020, 03:21 PM

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.

MrSmoothie · Mar 15, 2020, 03:18 PM

If I were having to remove the wings on my Do-335 for transport (which, thankfully, I am not), I'd install multi-servo connectors at the wing interface. As I'm thinking about it some more, multi-servo connectors at the wing interface would make the wing mating process pretty easy actually.

I use using multi-connectors on planes like this where you have 3 or more things to connect per panel (assuming there is internal room to stuff the connectors back into). I use ElectroDynamics. They are not inexpensive, but they work really well. I've got them in my FW DH112 Venom, FW ME-262 and HobbyKing 1600mm FW-190A, all of which I have to remove the wing panels for each trip to the flying field.

Just this morning I flew my VQ Models A-26 Invader. I hangar it at my dad's place due to the size and that it fits in his SUV, so only fly it occasionally. As a result, I did not use multi-connectors -- and was reminded what a PITA it would be on a plane I fly often! At least I color-coded all of the connections using small zip ties, trimmed flush, of corresponding colors, or I'd go nuts.

Twowingtj · Mar 15, 2020, 01:59 PM

MrSmoothie Very good suggestion to have the ventral fin replaceable. A simple tounge and groove with some ply and some blind nuts could do the trick.

I chose to repair mine as well, although mine didn't have quite as much damage.

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.

Oxotnik · Mar 15, 2020, 01:55 PM

In my opinion, this Do-335 is going to be a real PITA to connect wings in the field. Assuming that the Rx is placed on the raised platform behind the pilot's head, with the pull-pull nose wheel steering, the wing servo wires are going to have to be threaded under the servo platform and up through a hole in the platform between the pull-pull cables, so the the servo wires can be run upward between the pull-pull cables without the servo wires being chaffed by the pull-pull cables. Structurally, the wing is easily attached, but the wiring, not so much so.

If I were having to remove the wings on my Do-335 for transport (which, thankfully, I am not), I'd install multi-servo connectors at the wing interface. As I'm thinking about it some more, multi-servo connectors at the wing interface would make the wing mating process pretty easy actually.

MrSmoothie · Mar 15, 2020, 11:56 AM

I don't want to get too far ahead of myself, but I've been thinking that I'll eventually design and make 3D printed spinners for my DO.

I figured it was time to buck up and see if the fuselage fits in my car. Good news, it does. When loading, I took into account the eventual addition of the stab, cowl and props, and I think it will be just fine. Good thing there are two wing panels...

Oxotnik · Mar 15, 2020, 11:22 AM

I'm scratching my head a bit in regards to spinners. I've purchased a pair of 5055-390kv motors (FlightLine Spitfire) and MAS 16x10x3 tractor and pusher props. I'm having trouble finding suitable spinners though. I picked up a couple Dubro 3-blade spinners, but the blade slots are too small for the MAS 16x10 prop. I could pretty easily modify the slots a bit to fit the tractor prop, but it'd be pretty major surgery to make them work for the big pusher prop. Are there any good off-the-shelf options out there for 3" to 3 3/8" dia 3-blade spinners that'd fit MAS 16x10x3 pusher and puller props? Or will I have to special order them from TruTurn (which is a pretty pricey option). It just doesn't seem right to be spending more money on the spinners than I did for the motors. :-/

Oxotnik · Mar 15, 2020, 11:10 AM

Nick, bummer about the damage to your vertical stabilizers. I was a bit surprised with I popped the top on my 335 and saw that the stabs were supported better than they were. Luckily, my V Stabs weren't damaged in transit.

MrSmoothie · Mar 15, 2020, 10:38 AM

My Do335 arrived on Friday. I could barely drag the box from my front porch, through the house, through the carport, and into my shop. Um, and then what? I think the package size alone exceed my shop limitations.

I was happy with the double-boxing which appeared to have come through with only a few marks. However, I quickly discovered that my ventral fin had been smacked and crushed the lower fuselage at the leading edge. The tip of this fin was also fractured inside the covering. I saw somebody else had lower fin damage as well. The way they packaged this, such damage was inevitable. The tips of the two rudders go right up to the carton walls with just a bit of foam sheet. Any impact at all, and something's gotta give.

I put in a damage report to MRC, but I'm being careful about this. I do not want a replacement and will repair myself. I'm glad that MRC believed those of us on this forum who said a variation of "if you build it, they will come" -- or in our case, if you import it, we will buy it. I don't want to make them sorry that they did. But like all of you, I prefer to damage my planes myself!

To me, this should have been an easy fix on the design side -- make the ventral fin a separate piece, to be attached by the builder. I'd have made a ply tongue extend out of the lower fuselage to fit into a slot in the fin -- either glue or fix with two screws. Not to mention, the ventral fin is maybe the most likely part to be damaged flying, and this would have made a replacement part possible.

I was a little annoyed that the first layer of bubble wrap on the fuselage was attached with clear tape directly to the fuselage -- even carefully removed, it left a thick layer of adhesive on the covering. Typically I use isopropyl alcohol to remove adhesive, but this removes many paints as well. I did a test on the wing root and saw no effect on the covering, so that's what I used to remove the tape adhesive in three places.

My impressions: This thing is enormous. I still haven't had the guts to see if the fuselage will fit in my car (going over a fully reclined front passenger seat into the back seat. The wing panels won't be any problem.

I have mixed feelings about the "pre-weathered" finish. I can see where many will like it fine. I'd personally have liked to do that myself. If my flights are successful, I can see where, in the future, I might repaint this model.

The battery compartment is larger than I had been led to believe based on a few things I'd read. At this time, I'm thinking of a single, very large 6s lipo. I know a 6250 will fit, and maybe even a 7000.

I'm anxious to see how Oxo does with the two large motors -- I'm sure they will be enough power, if not too much. I've wondered about using a smaller motor on the tail -- can two dissimilar motors be run off of single lipo?

Here is a fairly recent video of an Aussie modeler flying his Black Horse Do-335. Note that he's running on 4s power, using two lipos (NOT in series). He has a link to a web page with more specifics about his setup. I think it's always helpful to see what worked for somebody else as a jumping off point. This, along with how things work for Oxo, will certainly help my decision.

https://youtu.be/3k8pfrBOYxM