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

[Alpha]

Alert to all you Pfeil owners, before we put it on the website, I wanted to post here on Hobby Squawk that we have a Pfeil that is new in the box except it's missing the plastic canopy. If anyone wants to save $100, PM me.

[edfen]

The numbers on the tail should be 102 to match letter code VG PH

[edfen]

The number on the tail should be 102 to match the letter code VG PH

[Twowingtj]

After a lengthy pause, while other projects took priority, the 335 finally had it's maiden.

The CG was spot on the recommended 175mm with a 6S 8Ah lipo about an inch back in the front hatch. She came in at 15.3lbs AUW.

The bird lifted off with ease using take-off flaps and felt real good on the sticks. There were no quirky tendencies at all. Just a nice heavy metal warbird feel. Two clicks of left aileron is all she needed.

Being a twin, with the rear motor behind four full tail surfaces, it has a sound unlike any other warbird. It's like a swarm of huge angry bees on steroids! Not what you want to hear coming up behind you if you're tooling along in your P-51.

It has a good, eye catching presence in the air.

Landing is just a matter of dropping take-off flaps(30 deg), keeping it pretty flat and controlling decent with throttle.

Didn't get vid or in flight shots.

[SanExup]

That looks amazing!

[Twowingtj]

I had a chance to fly the Do-335 at the Warbirds over Chenango Bridge event this last weekend. My wife was able to get a pretty good video.

As I mentioned before, this plane has a very unique sound. Most of it is generated by the rear prop positioned behind four flying surfaces.

We were dealing with a fairly stiff crosswind. I wound up with a bit more of a flare than planned. Luckily, I had reinforced the lower rear fin. No damage.

https://youtu.be/zCYN_KHHbdc

[paladin]

very nice tony!

Joe

[MrSmoothie]

Hey Guys, been a while since I posted here. I'm still flying my Do335, but not very often, as I've decided the Xwave retracts are marginal for the mains, and inadequate for the nose, at least at my increased flight weight. The problem is that the trunnion forks snap off (nose retract) as they carry the landing stresses. I'm lucky if I get even 2 or 3 flights sometimes, with landings that I thought were pretty darn good, landing on Geotex. But then you consider that above the nose gear is a 6000 or larger lipo, maybe 7 oz. of nose weight, two Talon 90 ESC's, 5055 motor, and large prop, and maybe not so hard to believe. On the mains, the stress is carried by the trunnion bearings, and they hold up fine. But with the weight of a Robart Scale Wheel (and gear door resistance), one or the other main typically stalls before fully retracting.

I think the Xwaves could easily be improved -- it appears that the trunnion is machined. Simply machine away less between the forks, and there'd still be plenty of clearance for the worm gear. The forks could be at least 1mm wider, and it wouldn't cost a thing to make them stronger. I don't know much about the grades of aluminum, but I suspect a different grade could help as well.

All that said, my Do335 is grounded for the time being -- I've gone through at least 3 or 4 nose retracts.

So, are there any options? I've never seen an Eflite, so don't know if it's any beefier than the Xwave. I believe it (their steerable nose gear) is made for a 4mm strut, so I'd have to drill out the trunnion. I've looked at Robarts, but I'm hesitant to spend more on retracts than the model costs. I know Hobbyking has some large retracts, but they are pretty much out of stock or "global" when you need another.

MotionRC: If you are going to get into large ARFs, I think you should consider an upgrade model of the Xwave for models 15+ pounds. I think they're find for 10-12 lbs. and have standardized on them for several of my other models -- makes it convenient to keep a spare or two on hand when you use the same unit in multiple models. They're priced right and MRC keeps them in stock -- two strong points in their favor. I just don't think they're best suited to the Do335.

[Twowingtj]

MrSmoothie On your mains stalling, check to see if the gear pins have gotten bent backwards some. I'm running Robart wheels on the mains as well. My wheels compress a bit with the weight of the model and tend to be a bit draggy in the grass. The gear pins supplied with the struts are soft and do bend rearward easily, causing the wheel to contact the backside of the wheelwell when retracting.

I've wanted to change out the gear pins to a standard hardened pin, but the strut grub screws are not drilled at 90degrees. They seem to be drilled wherever the maker wants to put a hole. Hence the non-flatted pin going into the struts. If the struts were drilled with grub screws at 90 and 180 degrees, we could change pins easily.

Luckily, knock on wood, I haven't had an issue with breaking nose gear retracts. And I'm carrying a 6S 8Ah pack up front.

[TwistedGrin]

I got in four flights on my Dornier 335 Arrow this Sunday........the right wing retract always needs an extra cycle while in flight to bring it down....thinking it may be binding up in the wheel well. I will be checking it separately later this week on the bench.

I am still amazed this aircraft is able to loop and turn on a dime. It's just a cool bird - LOVE it. However it is tender on the retracts.

My nose gear retract is just fine with the trailing link axle Oleo strut from a Freewing A10 80mm nose gear (MotionRC FJ311110811) / Have to insert a longer spring stopper inside the strut cylinder - stops the travel short of the prop striking the ground and compresses the spring spring

https://youtu.be/BLBWVqSAtIY

TwistedGrin

[TwistedGrin]

Got in another flight tonight....nearly dead calm but clouds were blocking the sun so it was getting dark super fast.....perfect flight, loops, aileron rolls, tight figure eights about 20ft flat even....ya it's an arrow....perfect landing. Cool bird!!

TwistedGrin

[Twowingtj]

TwistedGrin Nice video and great flight! I might go with the A-10 trailing link nose gear as well. Eases the stress on the nose retract. I haven't had issues with mine yet, but others have.

[ghethco]

Hi guys,

Getting mine ready to maiden... Have not been able to find any reference to flap -> elevator mixing. I've modified my flaps with offset hinges made from G-10, so full 60-70 deg deflection is possible. I'd like to take the guesswork out of flap -> elevator mixing if possible. Or did people find it isn't necessary?

Post edit -- found (on a different thread) the following worked for two people, one of whom also did offset hinges to allow more flap deflection: 6% down elevator mix for 1/2 flaps, 11% for full flaps.

Gary

[Twowingtj]

ghethco nice work on the hinges. Mine are still stock. It could use a few more degrees of deflection.

My elevator mixes are 2% less on each.

Looking forward to seeing your progress.

[paladin]

I've made some progress on the purchased parts for mine. retracts:

mains:
Xwave RM400-90 Electronic Retract Multi-Pack (2 Retracts) [XWA6015-004] Motion RC

nose gear:
#558RSE 105 deg Electric Nose Retract RoboStrut Ready – Robart Manufacturing

as for motors i am still ????

if i go with our std power it would be turnagy NTM 5060-380 turning 15x8x2 on 8s.

other 6s options being:
Xpwr 22CC Motor (extremeflightrc.com)

E-flite 60-Size Brushless Outrunner Motor: 500Kv | Horizon Hobby

any thoughts?

Joe

[Twowingtj]

paladin Interesting find on the 105deg retract. The Xpwr motor is what I'm running on the rear of mine.

[paladin]

paladin Interesting find on the 105deg retract. The Xpwr motor is what I'm running on the rear of mine.

very interesting!

how well does the xpwr push. i'm thinking a 5060-380 on 8s up front and the xpwr aft on 6s. 8s all the way forward and the 6s between servo bay and cockpit.

how much flap do you use?

Joe

[Twowingtj]

paladin On the xpwr, I'm running a MAS 15x7x3 pusher. I think is is producing a bit more thrust than the Spitfire motor up from turning a MAS 16x10x3. The rear motor is turning ~2400rmp faster as well.

The MAS 3-blades are not the most efficient props. APC 2-blades would be better, although not look as good.

I'm using a 6S *K lipo all the way up front and it needs the weight to balance. The rear compartment is pretty much full with the receiver, servos etc.

For flaps, using none on take-off and full deflection allowed mechanically, on landing.

[paladin]

the xpower with no slippage can achieve 73.6 mph with that prop.
the 5055-390 with no slippage can achieve 98.4 mph with that prop.


in my case:

(2x) 5060-380 on 8s turning a 15x8 APC-e (((3.7*8)*380)*8)/1056= 85.2mph

(1x)5060-380 on 8s turning a 15x8 APC-e = 85.2mph (+) (1x) xpwr -22cc on 6s turning a 15x8 APC-e = 84.1mph

prop wt factor published by AMA in the 90's = p*d(squared)

15x8x2 = 8*15*15= 1800
15x8x3 = 8*15*15*1.5= 2700 <= this means more of battery going to heat and shortening flight life

APC-e does make a pusher 15x8x2.

i would like to stay with standard bat size of 5000mah or 5amp.

Joe

[TwistedGrin]

Nose gear modificaton of the trailing link axle Oleo strut from a Freewing A10 80mm nose gear (MotionRC FJ311110811) / Have to insert a longer spring stopper inside the strut cylinder - stops the travel short of the prop striking the ground and compresses the spring spring. The A-10 80mm nose gear is short so it needs a spacer....I had a fixed gear strut mount from some other model and cut it to the length 15.5mm to match the same length of the original strut. I honestly can't remember if the original strut pin was used or I made a longer one. I do know that I use the bottom slot of the pin to use the set screw to hold the strut on instead of the spring....the slot needs widening sometimes to allow the strut to pivot freely. I use washers to fill the gap between the retract trunion and the steerin arm as it has to clear the retract to pivot correctly....the washers help the pin from bending too much. I may have had to drill into the retract trunion to allow the strut pind to get down into the the first grub screw.....I have had to do this on some other planes too (Maybe the Nexa OV-10?) The strut pin must be slotted so the grub screws can keep the alignment. I just use what I have in the bins and try to fabricate a solution....this is what I wound up doing.

TwistedGrin