1:4 Scale Foamy Albatros D.Va – Flite Fest 2022 Dawn Patrol Challenge

[willsonman]

A NACA exit or vent may also get added to the underside of the battery hatch.

I was informed that NACA ducts make TERRIBLE air exits. I think this is well-demonstrated by my Smoothie at SEFF where after every flight the ESCs would come down hotter than any other ESC should after not being pushed to max current. They are 60A ESCs pulling only 54A each so the problem really is proper air flow but there's not a lot I can do about it on that airplane other than make a big hole on the bottom and dramatically increase the drag.

Since you are going so slow on this airplane.. and I mean that in the most relative of terms compared to the Smoothie, I'd probably just opt for a hole. You could probably do some louvres on a 3D print if you wanna get fancy but that will greatly slow down the air flow. There were a couple of small ones on the sides but not nearly enough exit area for what we need. Maybe consider the cockpit opening as your exit area and call it a day.

 

[wilmracer]

Maybe consider the cockpit opening as your exit area and call it a day.

Cockpit opening is fully closed due to it being part of the servo hatch. I'll consider options though. For air exit from the cowl it is basically a "hidden" hole.

 

[Baron VonHelton]

Cockpit opening is fully closed due to it being part of the servo hatch. I'll consider options though. For air exit from the cowl it is basically a "hidden" hole.

If memory serves me, I think there was an exhaust ports somewhere in the cowling just for that purpose??



Ah, I think the 3 round ports on the side there?

 

[willsonman]

No, those are not exhaust. They are access panels for working on the inline engine. Refer to images of the other side of the aircraft and you'll see the exhaust manifold and pipe.

 

[Baron VonHelton]

No, those are not exhaust. They are access panels for working on the inline engine. Refer to images of the other side of the aircraft and you'll see the exhaust manifold and pipe.

Oooops!

Let me clarify, by "exhaust" I mean to expel heat out of the cowling, not the actual exhaust manifold. I knew the exhaust manifold is on the other side.

He can use those ports to allow the Flite Test Engine to breathe.

 

[wilmracer]

Updates from yesterday. Hatch is basically done. I need to make a small tweak to the hole where the pin locks in but it is CLOSE.

Spinner and backplate are CLOSE to balanced, at least before paint. I shot the paint last night and will let it cure today and then I'll start working my final balancing. Prop is just abot perfect by itself. My balancing method for props typically involves light coats of clear or matte coat on light areas until everything balances. Easy to do with props but harder with spinners. I'll get it right though. I'm SUPER happy with how this modified easter-egg is working as a spinner.

Rough shaped the small fairing at the forward fuse between the engine and the spinner. Again, not perfect but good enough for a foamy. It gets covered and painted to match.

Today will be busy but I hope to finish covering with the wooden vinyl, print a few more access hatches and vents, and if I'm lucky mask off and start painting the nose area. I'll likely need to setup the UV lights again as it took quite a bit of effort to get this paint to cure.

If I can get the interwing struts done this weekend I'll be in a fantiatic position to get a maiden in before FF. Flying wires should really just take one nice evening. I would LIKE to do rib stitching and have all the supplies but that is the lowest priority. That might be something I do between flights while onsite @ FF. Maybe while we're hanging in the STEM tent sharing these builds.

 

[wilmracer]

Oh, and regarding the access ports and small side vents, I've already modeled those. I resized the port and just painted a bunch and I've got a test print going now for the vent

 

[wilmracer]

Rest of the fuselage is wrapped in the wood vinyl and painted. Last time this paint took several days to fully cure and was helped along by heat and UV light, so this time I just went straight for the old aquarium light to hopefully fully cure it today...

 

[Baron VonHelton]

Rest of the fuselage is wrapped in the wood vinyl and painted. Last time this paint took several days to fully cure and was helped along by heat and UV light, so this time I just went straight for the old aquarium light to hopefully fully cure it today...

View attachment 226028 View attachment 226027

I've got 80 & 90 degree heat here? Wouldn't just setting it out in the sun dry it in an augenblik??

 

[wilmracer]

I've got 80 & 90 degree heat here? Wouldn't just setting it out in the sun dry it in an augenblik??

I'm not a big fan of leaving unattended models outside while I'm at work. If I was working from home today I'd probably do the same, but of course humidity can impact drying time as well and we don't get "dry heat" in this area.

I know it looks silly but last time this enamel paint was still tacky after a few days and a few hours of this light cured it.

 

[Baron VonHelton]

I'm not a big fan of leaving unattended models outside while I'm at work. If I was working from home today I'd probably do the same, but of course humidity can impact drying time as well and we don't get "dry heat" in this area.

I know it looks silly but last time this enamel paint was still tacky after a few days and a few hours of this light cured it.

WHOA! Impressive! Is that just an ordinary neon light?

 

[wilmracer]

WHOA! Impressive! Is that just an ordinary neon light?

No. It is a light fixture for use on salt water reef tanks. It has a pair of 48" T5 bulbs @ 54 Watts each. The bulbs are actinic with the highest output around 450nm. I used to use 2 of these fixtures paired with some LEDs over my reef tank and the corals loved them (all LED now for more control/options). In principle it is similar to a grow light for indoor hydroponic gardens and stuff like that except the intensity is higher as you have to get adequate PAR values underwater (PAR being a measure of light within the portion of the spectrum favored for photosynthesis).
I wouldn't recommed people run out and grab these just to cure tacky enamel paints, but if you've got them lying around they seem to work well.

 

[willsonman]

Yeah I swear by UV curing paint but only if you are fully attending. Foamies do not like the sun too so this is another great reason to use the lamps.

 

[wilmracer]

Teaser... more balancing needed but the spinner is going to work...

 

[Tench745]

I love that feeling. Great job!

 

[wilmracer]

Well, Apparently the QC for the lozenge fabric isn't great and there is a noticable discrepency in coloring on the fabric for the lower right wing panel. TBH I'm kindof pissed given how much this stuff cost, but at this point there is nothing that can be done if I want this done before FF. I'm going to chalk it up to a field repair with that wing having been shot up and replaced/repainted separately from the others.

I did get the lower mount posts for the inter-wing struts installed this evening too. I've got plans to see the new Top Gun movie tomorrow evening so there won't be much getting done then, and Wednesdays suck at work, but I'm going to try hard to at least have the struts done (if not painted) before my daughter gets here on Friday. That will leave ailerons and flying wires and she will be ready for maiden...

 

[wilmracer]

I'll also add here... As noted all that is left to add are ailerons, flying wires, and interwing struts. The aileron servos and hardware are tucked in the fuselage below the servo tray so I won't lose anything. There are also a few SMALL cosmetic items like the coolant pipes and windscreen. That being said I put her on the scale last night WITH the 5lb 6s 20,000mAh battery. Current weight with that pack is just a hair over 19lbs. I haven't tested CG yet and won't bother until she's done.

So, the maths

The Proctor Enterprises 1:4 scale D.Va is very historically accurate:

• Wing Area 1,950 Sq. Inches
• 20lbs (unsure if AUW or dry)

That results in a cube loading of 6.4, pretty safely in the trainer to parkflyer range.

I "cheated" and added an extra 2" to upper and lower span (1" per panel). TBH this was really just done so I could say the span was over 90" (true scale would be 89"). Given the chords this results in somewhere around 45 additional sq. inches of wing area. There is also a deviation from "true" scale where the lower wing meets the fuse resulting in a few more sq. inches of wing, so I'm calling it an additional 50 Sq. inches of area to keep the math simple.

• If I come in at 20lbs, like the Proctor, I'll be at a cube loading of 6.2. Perfectly respectable, and I should have about 110 Watts/lb to boot.
• WORST CASE if I hit 25lbs (I won't) I'll be at 7.7, which is on the low end of general Sport/Scale models, with just shy of 90 Watts/lb.
• IF she balances nose-heavy with the 20,000 mAh pack I have the option to swap in one of my go-to 6s 8000 packs. That could get the weight as low as 18ish. That is a cube loading of 5.6. Solid trainer range with >120 Watts/lb and pretty damn close to 1:1 thrust to weight.

So, yeah... a 20lb foamy is a bit heavy, but I'm not worried about it.

The P-40 is about 22lbs and is a kite with a cube loading of about 10. This model weighs less and has about 475 more sq. inches of wing...

 

[willsonman]

Good maths indeed. I'm willing to bet that the p factor on this will not be nearly the same issue as with the P-40. Looking forward to some finished shots, preferably with space between the wheels and the ground.

 

[wilmracer]

Good maths indeed. I'm willing to bet that the p factor on this will not be nearly the same issue as with the P-40. Looking forward to some finished shots, preferably with space between the wheels and the ground.

Yeah, I don't expect the P-factor to be a factor

IDK when maiden will take place but I'll let you know as soon as I know. June 4th or 5th look promising so I'll keep my eyes on the weather. Do you think it would be worth hitting DCRC? Winds @ Lorton are typically higher and as much as I love Poplar Ford and think the grass there would be the best overall it does have more trees to contend with.

 

[Baron VonHelton]

Yeah, I don't expect the P-factor to be a factor

IDK when maiden will take place but I'll let you know as soon as I know. June 4th or 5th look promising so I'll keep my eyes on the weather. Do you think it would be worth hitting DCRC? Winds @ Lorton are typically higher and as much as I love Poplar Ford and think the grass there would be the best overall it does have more trees to contend with.

There might be an app for that.......