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

[Oxotnik]

TJ, glad that you finally got started on your 335. We've gotta keep the war effort moving ahead. I did receive my 6S-8AH battery. I went with 3S-8AH batts and soldered up a series connector. Two things that I like about the coupled 3S batts: (1) if I loose a cell, only one 3S battery has to be replaced. (2) Since a 3S is much slimmer than a 6S, I can offset the batteries. So, the bottom battery slides all the way to the firewall and the rear one is back a bit (there's not enough room for a 6S to slide all the way forward to the firewall.

[OV10]

The other benefit of using serial LiPo set ups is the better heat sloughing which in the long run helps to increase longevity with better IR's over time.
I replaced my whole LiPo support structure with 2&3S 5000mAh packs whereas I can do any combo of higher voltage(4-12S)

[Oxotnik]

I’ve been chatting with a few folks offline and repaints have come up. As I was doing some very basic internet searches for information on the Do-335, I found this reference to some paint schemes, with the RLM colors specified.

http://www.rlm.at/cont/profil15_e.htm

[MrSmoothie]

Assuming one wants to do a scale scheme that actually was applied (as opposed to a "what if" scheme, had the Pfeil reached operational status), there are really only two color schemes: RLM 81/82 or RLM 70/71 splinter, with RLM 64 undersides. Markings were very similar -- just difference in code letters and prototype numbers for the most part. If/when I repaint, I'll be doing RLM 81/82, since I accidentally purchased 29 oz. cans of each color (BEHR latex) one time, when I thought I was getting the usual sample size!

EDIT: I found another source that looks very well-researched, and the indicate upper surfaces originally specified as 70/71, but probably 80/81 or 81/82 by the time the prototypes were completed. Often, late war Luftwaffe colors are best-educated guesses on the part of historian/modelers on a nerd-level far above my pay grade! An even better example are ME-163 colors -- almost entirely guesswork and interpretation of photos.

The Do335 at the Udvar Hazy (restored by Dornier) appears to be 81/82.

[Oxotnik]

I had a couple PMs, asking about the warbirdpilots.com pilot that I’m using. So, having nothing else to do this evening, while I’m locked inside, keeping the plague outside, I decided to open up the cockpit to take some photos.

You can see in the photos how I cut the seat and the floorboard for his legs. I ran a balsa stick through the bottom of his parachute harness, to keep him pulled down in the seat, and Velcro on his back to keep him pulled back in the seat. When cutting holes in the plastic, cut carefully as the plastic is VERY thin in places and will actually rip, as it’s being cut. Cut very slowly and steadily.

I did not glue the cockpit nor the canopy in place. Instead, I used #2-56 buttonhead sheet metal screws to secure them to the fuselage. I used 5 screws for the cockpit and 6 screws for the canopy.

Before putting him back in the cockpit, I removed his life vest, since he’ll be flying Defense of the Reich missions and not over the English Channel or the Med. In one photo, he’s wearing the vest, and not in the other photo.

[downwind3zero]

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Got the German pilot in.

[OV10]

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Got the German pilot in.

Another outstanding "office" mod

[Oxotnik]

Sieg hiel!

Downwind, very nice.

[MrSmoothie]

For anybody that's interested, I decided to start a Build Log for my Do335 over on RCGroups. Not sure if it's cool to post a direct link to it or not (what is the Hobbysquawk policy on that?).

I'm documenting my basic build as well as where I'm deviating a little from the instructions. A shout out to Oxotnik for "paving the way" so that I have fewer mistakes that I have to go back and correct!!! Also, I do want to add that I find the advice, ideas and opinions to often be more helpful/serious here on the 'Squawk.

As I proceed, my modifications and detail additions will get more involved. Some things you have to do right from the start, however, as they would be hard to do after a maiden.

[Twowingtj]

MrSmoothie Feel free to post the link to your log. No policy against it that I'm aware of.

[Oxotnik]

Nick, I’m glad that you’ve found my trials and errors and musing helpful. I’ve enjoyed the build. There have been no bad surprises. I’m looking forward to following your build. I’d started a Black Horse Do-335 thread on RCG, but there hasn’t been much interest.

All that I lack to complete my build and to be ready for the maiden flight is the aft TruTurn pusher spinner. I’m hoping to get that this week.

[MrSmoothie]

OK Gang, here's the link to my RCGroups Build Log: https://www.rcgroups.com/forums/show...k-Horse-Models

There hasn't been much interest to start. I guess there are two dozen of us with the plane and we all know who we are!

Making good progress in the shop today but what I've posted is a few days behind where I actually am in the process.

[MrSmoothie]

All that I lack to complete my build and to be ready for the maiden flight is the aft TruTurn pusher spinner. I’m hoping to get that this week.

Are you going to maiden with the 16 x 10 x 3 props, or did you decide on something else?

By the way, am I the only one who noticed that on Motion's site, the rear propeller is mounted backwards (so that it fits in the standard spinner cutouts)? Kind of funny. Hey Kids, don't try this at home!

[Twowingtj]

I'm thinking of trying something a little different power wise on mine. Going to use the Flightline 5055-390kv with the MAS 16x10-3 up front. In the rear I'm going to try an Extreme Flight Torque 4016T/500kv with either a 15x7-3 pusher or 14x7-3 pusher. The choice for the rear was driven by the fact that I already had the motor and it needed a home. This will all be powered by 6S.

The Torque motor is the same one that powers the 84" Turbo Bushmaster very effectively. The concern with using the 15" prop is that it may overpower the front end. Swapping ends in flight might not end well.

On the full scale, there is a noticable diameter difference between the front and rear props. This set-up will allow that without sacrificing overall power.

Anyone know of any potential problems running different motors might cause in a pull / push configuration?

[downwind3zero]

Oxotnik How did you secure the aft motor (I am using the same as you are), ie how did you get locknuts in behind the panel or did you use another method? trying to figure this out before I go for it. Thanks

[OV10]

I'm thinking of trying something a little different power wise on mine. Going to use the Flightline 5055-390kv with the MAS 16x10-3 up front. In the rear I'm going to try an Extreme Flight Torque 4016T/500kv with either a 15x7-3 pusher or 14x7-3 pusher. The choice for the rear was driven by the fact that I already had the motor and it needed a home. This will all be powered by 6S.

The Torque motor is the same one that powers the 84" Turbo Bushmaster very effectively. The concern with using the 15" prop is that it may overpower the front end. Swapping ends in flight might not end well.

On the full scale, there is a noticable diameter difference between the front and rear props. This set-up will allow that without sacrificing overall power.

Anyone know of any potential problems running different motors might cause in a pull / push configuration?

TJ, is this a visual you are observing from pics?? From multiple sources I've researched (including Wikipedia's Pfeil) the engines were the same and the props are the same diameter/pitch other than being tractor/pushers.
The props are 3.5m(11.5 ft) in diameter whereas the scale of this model as noted in the first post has the prop at 17 but most seem to think that the MAS 16x10x3 is the best bet to go with.
By going with 2 different sized kV motors turning different size/pitched props, I'm concerned that you are going to run smack into a possible engineering issue known as aerodynamic hysteresis.
Every inline tractor/pusher airframe made (Pfeil, Skymaster, Moynet Jupiter, Rutan, ect) had the same size engines and props fore/aft probably for real aerodynamic reason.

[Oxotnik]

Oxotnik How did you secure the aft motor (I am using the same as you are), ie how did you get locknuts in behind the panel or did you use another method? trying to figure this out before I go for it. Thanks

I drilled new holes, just a few small fractions of an inch outboard of the existing 3mm tee nuts and used #4 sheet metal screws to secure the motor to the bulkhead. I’m very comfortable with the strength of this setup.

[downwind3zero]

Thanks for confirming, that's an option I was contemplating.

[handyman220]

OK Gang, here's the link to my RCGroups Build Log: https://www.rcgroups.com/forums/show...k-Horse-Models

There hasn't been much interest to start. I guess there are two dozen of us with the plane and we all know who we are!

Making good progress in the shop today but what I've posted is a few days behind where I actually am in the process.

Thanks for the building log link. Will be awhile before I start building/assembling mine so more options are better in my opinion. Did not notice the prop on motions site until you mentioned it! Duh! Very nice repair work by the way. I have yet to unwrap mine to check for damage, have to get off my butt, too many other projects.

[MrSmoothie]

J, is this a visual you are observing from pics?? From multiple sources I've researched (including Wikipedia's Pfeil) the engines were the same and the props are the same diameter/pitch other than being tractor/pushers.
The props are 3.5m(11.5 ft) in diameter whereas the scale of this model as noted in the first post has the prop at 17 but most seem to think that the MAS 16x10x3 is the best bet to go with.
By going with 2 different sized kV motors turning different size/pitched props, I'm concerned that you are going to run smack into a possible engineering issue known as aerodynamic hysteresis.
Every inline tractor/pusher airframe made (Pfeil, Skymaster, Moynet Jupiter, Rutan, ect) had the same size engines and props fore/aft probably for real aerodynamic reason.

Interesting -- I'd already scaled a couple of different better quality scale drawings which show the front prop being larger than the rear. I just checked the specifications chart in "Monogram Close-Up 21: Do335" and it indicates the front prop as being 3.5m dia., and the rear prop being 3.3m dia.

Another source indicates that in single engine tests, the plane flew faster with just the rear engine. Either it comes down to greater efficiency of the pusher prop (using smaller diameter), or perhaps the stress on the drive shaft which was apparently under-strength and problematic throughout testing...

I too had wondered how it would fly with a slightly smaller motor on the back with a one-inch smaller prop (16" front, 15" rear). Regardless, I'm now on the course of identical motors/props front/back.