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

[OV10]

Chuck, speaking of good calls, that Eflite prop adapter find is awesome.
I just printed this page to put with my reference tech data for future use.
Why hog out a spinner back plate for a hex shaft if ya don't have to

edit ………. just looked at the pic of that EF prop shaft.
I assumed that it had a smooth shaft but not so.
But is still a good scavenge.
Here's a direct HH link to the EFL11595

[Oxotnik]

Okay, Charlie, I was thinking that the Admiral 5030 was closer to 500kv. 200 W/lb is very respectible, no doubt. I stopped by my LHS again today (BTW, they offered to make me a cot in the backroom, since I seem to be there every day or so.... LOL). I found an 8mm EFlite prop adapter with the same hole pattern as the Freewing 5055s, but the prop shaft is about 3/4" longer. It's the prop adapter for the 1.3m EFlite Extra 300 (EFL 11595), In case anyone is interested.

This morning, I drilled out the back plate of the TruTurn backplate to 12mm (to fit over the hex 'nut' at the base of the prop adapter (from the Corsair's 5055-340 motor) and reamed the MAS prop out to 10mm. Used a star lock washer between the backplate and the prop adapter (to keep the aluminum-to-aluminum surfaces from sliding) and put a 10mm washer between the prop and the prop nut, and everything tightened down nicely. The prop nut takes a 3mm screw to attach the spinner to the rest of the prop assembly. Unfortunately, the TruTurn spinner is long and I couldn't find a 3mm screw long enough to reach it (that long would probably be too long for a 3mm screw anyway). So, next step - drill and tap the prop nut for the 5mm screw that comes with the TruTurn spinner. Since I got the TruTurn spinner to work for the tractor motor, I need to order a TruTurn for the pusher motor/prop. Since I'll be ordering it, I'll have TruTurn anodize it black. I'll have to paint the shiny alumimum tractor TruTurn spinner that I already have.

So, now everyone is caught up on my Pfeil shenanigans (maybe, I should start calling them 'Pfeilnagigans'... :-) ) for the day.

Charlie, good call on the Spitty 5055s. They're taking a bit of work for this application, but they're going to work out very nicely in the end. No pain, no gain, right?

[OV10]

The recommended Admiral 5030-400kV is only 10kV more than the Spitty motor but here is where the real point that you're missing is Chuck.
The Admiral has only a 1180W rating. The Spitty spanked that by 200 watts and didn't even come close to its max of 1950W.
The spec on the 5055-390kV Spitty motor product page for max wattage still hasn't been corrected .........reads 950W(confirmed to be incorrect 2 years ago by Alpha)
So the watts that you tested out is approx. the same as I got almost 2 years ago when I tested for the A-26.
Now then……….. you are getting power that is on the verge of 3D power for $30 per motor less expensive...………. I say that is a :first_place:win

[Oxotnik]

Okay, I've got some bench test numbers for the Spitty 5055-390kv motor and MAS 16x10x3 prop.

Configuration:
Motor: Freewing 5055-390kv
Prop: MAS 16x10x3 prop (tractor)
ESC: Hobbywing Skywalker 80A
Battery: CNHL 6S-5AH, 70C, full charge

Results (about 10 seconds at WOT):
Current: 56.6 Amps
Power: 1345 Watts

Power/mass (assuming that the AUW is 13.5 lbs, and that the same config is run for both the tractor and pusher power trains) = 2*(1345W)/(13.5 lb) = 199.3 Watts/lb


I was a bit surprised at lowish value of the current draw, but at 199 Watts/lb, this dual power train should work well for the 335, but it won't be a speed demon. For those considering a Power 60 class electric motor and 16x10x3 prop, I'd encourage to maybe look for a motor with a bit higher kv. I believe that the recommended Admiral 5045 (IIRC) motor has a higher kv. Having not already invested in these Spitty 5055=390s, I might have gone with the higher Kv Admirals.

But, on the up side, the underperformance (in regard to power draw) probably means longer flight times....

[OV10]

[Oxotnik]

I knew ya would work it out, was just sitting in the wings and was gonna give ya a day before suggesting the same to ya

Thanks, Pa. I feel all grown up now.

[OV10]

Yeah, I was thinking that I may need to find a local machine shop and have them cut me two adapters with the same 3mm hole pattern and a longer 8mmx1.25mm prop shaft.

[edit] Found a solution!!! The prop adapter for the FlightLine Corsair's 5055-320 motor fits on the the Spitty's 5055-390 motor. This adapter a thicker prop shaft (it looks like 10mm to me, versus the Spitty's 5055' 8mm shaft), but it is significantly longer, too. I'll have to drill out the TruTurn backplate to 11mm or 12mm (to go over the hex 'nut' at the aft end of the prop shart) and ream out the MAS 16" prop to 10mm, but it'll work. Now, to order a couple F4U prop adapters from Motion. I like simple solutions. LOL

I knew ya would work it out, was just sitting in the wings and was gonna give ya a day before suggesting the same to ya

[Creative RC]

I ran the RimFire 1.2 (450kv) in ecalc and it turns the 16x10x3 quite well and with a lot of thrust, maybe even too much with two motors. Maybe that motor in the front and a smaller motor at the rear. It weighs 400 grams, just a bit less than the 5055 motor. But when putting it on 5s or simulating less throttle it talks about pitch speed should be double stall speed.

With two props of the same size and pitch, would the rear motor and propeller be working less hard (using less amps) due to being fed air (pressure) from the front propeller. If that is the case, maybe the one in the rear could get away with a higher pitch. For example a 16x8x3 in the front and a 16x10x3 at the rear. It would be an interesting experiment.

Interestingly, the fellow in the video with his 4s setup using the same Turnigy SK3 4250740 with 13x8x3 props was getting 57 Amps on his front motor and 45 Amps on the rear motor. He thought it might be on account of the long power cable to the rear but I suspect not.that alone.

[Oxotnik]

Corsair 5055-320??? Hope you mean 5055-340. Following you closely Oxotnik, I need all the professional help I can get on this one! Waiting to see what props you come up with before I order anything.

Yep, the Corsair 5055 is 340kv. My bad. Sorry.

I'm just fumbling my way though this. I'm making it up as I go. When I put the motors and props on the wattmeter, then I'll have some good info to report, instead of just supposition and intuition.

[handyman220]

Corsair 5055-320??? Hope you mean 5055-340. Following you closely Oxotnik, I need all the professional help I can get on this one! Waiting to see what props you come up with before I order anything.

[Oxotnik]

You could probably source a longer prop adaptor

Yeah, I was thinking that I may need to find a local machine shop and have them cut me two adapters with the same 3mm hole pattern and a longer 8mmx1.25mm prop shaft.

[edit] Found a solution!!! The prop adapter for the FlightLine Corsair's 5055-320 motor fits on the the Spitty's 5055-390 motor. This adapter a thicker prop shaft (it looks like 10mm to me, versus the Spitty's 5055' 8mm shaft), but it is significantly longer, too. I'll have to drill out the TruTurn backplate to 11mm or 12mm (to go over the hex 'nut' at the aft end of the prop shart) and ream out the MAS 16" prop to 10mm, but it'll work. Now, to order a couple F4U prop adapters from Motion. I like simple solutions. LOL

[MANFRED]

You could probably source a longer prop adaptor

[Oxotnik]

Nick, when I decided on the Spitty 5055-390kv motor, it was based on me liking the SK3 5055-430 (which I can't get at the moment) with 14x8x3 props for the 17 1b A-26. I'd have no qualms running that power train again for the 335. As the 335 will significantly lighter and less draggy than the A-26, that power train should do well for the 335. Plus, this power train was no pulling near the wattage that the motor could handle. Unfortunatley, the SK3 5055-430 wasn't available and the next closest I could find in that size class and kv was the Spitty 5055-390. But, increasing two inches in prop diameter should result in a power increase (intuitive assumption, based on one data point). It does concern me that the Spitty is running this motor with a 16x10x4 prop; so, by dropping a blade, I'll be giving up some power per motor. But, I'm doubling up the motors. So, again, in the absence of experimental data, I expect the power of the motor with the MAS 16x10x3 prop to be good for the 335. One day this week, I'll put the 5055-390 and MAS 16x10x3 on a wattmeter to see what it actually does. if I were to decide to go down an inch in diameter, I believe that the power output would still be good. I'll also put a MAS 15x9x3 on the motor and see what the wattmeter says. Unfortunately, I stopped by my LHS today, hoping to pick up a pusher MAS 15x9x3, but they didn't have any in stock. I hope that MAS offer a pusher 15x9x3; I haven't checked yet.

Another set back... My LHS had some TruTurn spinners on the shelf. I grabbed a 3.5" 3-blader spinner, which fits very nicely on the MAS 16x10x3 Tractor Prop, but very unfortunately, the friggin prop shaft on the Spitty 5055 is too friggin short for the spinner/prop. UGH! If it weren't for bad luck, I'd have not luck at all. Gloom, despair, and agony on me.

[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.

[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.

[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,

[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.

[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]

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.

[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.