P-38 Lightning-Roddie style..

Here's what my fillets look like after sanding-out with some crocus-cloth.




The crocus-cloth is nice.. in that it cuts the spackle quickly and is "cloth-based".. so it does not crease easily when curled into a tight radius.



I should do a 2nd app... but I'm not going to go crazy here. I also have more work to do on the controls.. so there's the possibility of some "dings" happening.

rsv1cox wrote:Standard European WWII paint scheme with invasion stripes...................

That's what I'm thinking for my "copy everything roddie did" profile P-38.  Imitation is the sincerest sort of flattery.  It's been 40 years since I built mine so it's time for another.  Scoping out my balsa stash now.  Engines are never a problem.  Gotta get started soon, 70 degrees here today, Spring is coming and the MG is waiting.  

Bob

I would LOVE to see you build one Bob!!! This one has been really enjoyable for me. My other Lockheed models' "wing" looks a little better after sanding-out too..




and the little "Flying-Blind" speed-model got some fillets..

I bought the rattle-can paint today, that I'd been procrastinating over..




I don't know how the "satin" will work out.. but that's the finish I want. I'll have to test-spray a few pieces of wood.. let the paint cure for a couple of weeks.. then subject it to some glow-fuel and see what happens.

You got any lustercote coat CLEAR you can cover with ? I don't think that Saitan by itself will do even 25% nitro  ,, But will depend on how much it is flown   Looking good!!, the plaster job done pretty good after the fact I am going to bee the Ass i am and ask >>. Why did you not round the engine block mounts ?!?

getback wrote:You got any lustercote coat CLEAR you can cover with ? I don't think that Saitan by itself will do even 25% nitro  ,, But will depend on how much it is flown   Looking good!!, the plaster job done pretty good after the fact I am going to bee the Ass i am and ask >>. Why did you not round the engine block mounts ?!?

I "do" have some Lustre-Kote.. but it's gloss. Maybe Lustre-Kote can be made "matte" once cured, by rubbing-out with fine steel-wool? I actually saw some rattle-can satin-clear Krylon where I bought the blue paint.

Regarding my engine-mount blocks.. I suppose I could round the back edges with a dremel drum-sander. They're hardwood blocks. Just about all of my designs for radial-mount engines use them. I know they look a bit fugly.. and most profile kits for radial-mount engines use balsa "cheeks" faired-back toward the wing's leading-edge. The issue with cheeks for me is; they take up nose real-estate for mounting an external fuel tank. I like to mount my tanks as close to the engine as possible.. using the shortest possible fuel-line. Engine cowlings would take the curse off the bare-blocks look.. but a cowling on a profile-model is tough to make look good.

Well its up to you i was just wondering and as you said : ; Engine cowlings would take the curse off the bare-blocks look.. but a cowling on a profile-model is tough to make look good.




Unless you were to make some fairing that would make things better But a lot of extra work 

getback wrote:Well its up to you i was just wondering and as you said : ; Engine cowlings would take the curse off the bare-blocks look.. but a cowling on a profile-model is tough to make look good.

Unless you were to make some fairing that would make things better But a lot of extra work 

Yea buddy.. about that "extra work"... I honestly need to be committed for some of the thoughts that I put into my models.. and "this one" is no exception. My aim was to install a bellcrank using a machine-screw and lock-nut.

This is a Sig #234 1/2A Nylon bellcrank.. with its' "bearing" drilled-out to accept a 3-48 machine-screw.



Look at the photo for a bit... because I spent WAY TOO LONG making this assembly.. (thanks...) The brass tube/bushing is a standard 1/8" OD tube that I cut to length using my X-Acto mitre-box. The models' sheet-wing is thinner than 1/8" after sanding. It's actually under .100"... so the bushing needed to be thinner than 1/8".

Lately.. I tend to build my flying-models with hardware designed to test time. It's kind of silly I know... but if someone takes possession of my models after I'm gone.. I'd like them to know that I meant for them to last as long as possible.

..lead-out guides today.. maybe..

It's looking great roddie and coming along quickly now. Not too long before prime and paint. I'm sure all those attachments will be removed first.

You must have wrestled with the cockpit detail, painting it on correctly can be a make or break. I made a mess out of the cockpit on my profile Mosquito. The way that Jim did his was so much better. I hope you kept a picture of Jims.

Thinking about my prospective profile P-38. Twin .049's, been there. Twin Enya 09's, been there on my Mosquito. Done twin Enya .15's in the past. But, twin ganged third line throttle controled Enya 19's, that's different. Will need to double up on the profiles which means a new order from SIG.

Bob

Well i looked at the Fine looking job you did on the Bellcrank leads for like 5 min.s or at least till i stopped laughing when you said it TOOK WAY TOO LONG !! Hell i am still smiling < Thanks , the plane is coming along nicely Roddie O hea i am in the process of cleaning that want to bee a work (hobby) table , little more organizing am i will bee ready to make a Mess !

Nice job, Roddie,

when will you maiden it and with what engines?

rsv1cox wrote:It's looking great roddie and coming along quickly now.  Not too long before prime and paint.  I'm sure all those attachments will be removed first.

You must have wrestled with the cockpit detail, painting it on correctly can be a make or break.  I made a mess out of the cockpit  on my profile Mosquito.  The way that Jim did his was so much better.  I hope you kept a picture of Jims.  

Thinking about my prospective profile P-38.  Twin .049's, been there.  Twin Enya 09's, been there on my Mosquito.  Done twin Enya .15's in the past.  But, twin ganged third line throttle controled Enya 19's, that's different.  Will need to double up on the profiles which means a new order from SIG.

Bob  

Thank You Bob! Yes.. the control-system parts will be removed prior to painting.. but I'll probably just cover the gear-struts rather than remove them.

Below is the link 944jim's BMH Mosquito-build. The fuel tank location seemed to be an issue.. I wonder how/if he found a solution.. Very cool paint/trim on that model!

https://www.coxengineforum.com/t10666-bhm-mosquito-in-ms-build?highlight=mosquito

Twin throttled Enya .19's sounds ambitious! I didn't know that you had any Enya engines..

getback wrote: Well i looked at the Fine looking job you did on the Bellcrank leads for like 5 min.s or at least till i stopped laughing when you said it TOOK WAY TOO LONG !! Hell i am still smiling < Thanks , the plane is coming along nicely Roddie O hea i am in the process of cleaning that want to bee a work (hobby) table , little more organizing am i will bee ready to make a Mess !

Thanks Eric! yea... I had to mess around EVEN MORE with that bellcrank yesterday. I had drilled-out (enlarged) the nylon bearing's hole for the 3-48 machine-screw. The assembly was binding.. so I had to open-up the hole a little more. Then I had to shim under the bellcrank with a few flat-washers to allow my pushrod to move freely. It attaches via an "L-bend" which created another binding-issue against the wing. That was probably the actual cause of the assembly binding.. Because of having to shim the bellcrank, this required me to cut a longer screw to compensate. blah blah blah...

Keep up the work on the table/bench Eric! Soon you'll be cutting-up some balsa. It always make me feel good!

balogh wrote:Nice job, Roddie,

when will you maiden it and with what engines?

Thanks Andras! If I started the paint-process today.. the model wouldn't be ready to fly for at least another month. We're looking at sometime in "April".

Planned-engines are Cox .049 reed-valve, configured as "product-engines" (Sure-Start type horseshoe backplates/carbs.. except without choke-tubes) and probably #1 cylinders. That's the "plan".. but if I encounter a severe tail-heavy condition after painting.. I drilled the engine-mounts to also accept Bee-style engines.. and have a pair of Golden-Bees that I could try. I'm counting on the former option though. Whichever.. I want them to be fuss-free/easy-starting.. at least for the maiden-flight and until I get used to how it fly's. I also plan to run those DAL 5 x 4 L/H props on both engines.

I was always fascinated by twin COX engine powered planes!

The L/H props is really a good idea to have the gyro torque pull the bird outward from the CL circle. I am looking forward to hearing/reading from you.

balogh wrote:I was always fascinated by twin COX engine powered planes!

The L/H props is really a good idea to have the gyro torque pull the bird outward from the CL circle. I am looking forward to hearing/reading from you.

Andras my friend, "thank You" for the encouragement. It's anyone's guess whether this airplane will fly. Most people don't realize what's involved in designing a flying model. It's probably much easier to design a control-line model.. than it is to design a free-flight or radio-controlled model.. (excluding a control-line precision-aerobatic model)

It's a thrill for me.. to be able to achieve controlled-flight of my designs. If they're capable of aerobatics.. all the better!

I have only designed/built one other multi. My 1st started-out as a "single-engine" self-designed model for Cox .049 reed-valve (Babe/Golden-Bee) power back in the early 1990's. As a single-engine model.. it was terribly under-powered. It had a HUGE plank-wing (1/8" thick x 6" chord x 30" span..) and a sprung landing-gear design and heavy-wheels that probably weighed 2 oz. in itself..

I would later fashion two cheesy engine-mounts attached to the leading-edge of the wing.. to which I would bolt "two more" engines.

and the model was no longer under-powered....

I still have it..  




The central engine-mount (nose) broke-off at some point.. along with the undercarriage/landing gear. It could still be hand-launched and flown as a twin though.

You are at a point now where you could install your engines and get a ball-park idea of where your balance point is, paint or no paint.  

Our two P-38 models are very close in size but probably quite different in weight.  I think I posted pictures of mine sitting on a scale but I have forgotten what the weight was.  Your model should be much lighter.  

My model balances perfectly at the leading edge of the wing, back about a half inch and it becomes nose heavy but not to the point where it does not fly, circles only.

You might get away with the complexity required of those product engines, pegs, bands, remote fuel tanks and all.  But I would recommend your stunt tanked Golden Bees over them in a heartbeat.  Golden Bees have always been my best running, easiest starting, and most reliable Cox engines.  

Looking forward to April

Bob

Ok roddie. Question time! Unless I missed it somewhere along the way... What is the reasoning behind the leadouts going through the inboard nacel(?) and fuselage and ending up just inside the outboard nacel? In laymans terms, why are the leadouts and control rod on teh outboard edge? Or is there any reasoning, and you did it just because you chose to? Thanks. And looking good, getting closer to teh end of the build!

NEW222 wrote:Ok roddie. Question time! Unless I missed it somewhere along the way... What is the reasoning behind the leadouts going through the inboard nacel(?) and fuselage and ending up just inside the outboard nacel? In laymans terms, why are the leadouts and control rod on teh outboard edge? Or is there any reasoning, and you did it just because you chose to? Thanks. And looking good, getting closer to teh end of the build!

I did explain why, early-on.. but it wasn't in the form of a topic. Many readers could have missed it.

Because the elevator is "inside" the tail-booms; its control-horn is also on the inside. To mount a bellcrank conventionally (inboard) posed more than one issue. Bellcrank operation would have required a long slot to be cut in the nacelle; compromising the integrity of the wing-joint. The "pivot" point (bellcrank screw location) would fall directly on the nacelle.

Mounting the bellcrank inboard of the cockpit module leaves no means to support the 11.0" length pushrod from flexing.

The Sterling P-38 kit S-17 references installing the bellcrank "backwards" (see below)..




I suppose I could have done it the "Sterling" way.. but it still involves routing the lead-outs through the inboard nacelle.. and I don't like the idea of that lead-out/pushrod intersection. It just seems like an accident waiting to happen.

My application simply utilizes the "outboard-nacelle" similar to a conventional profile-model control-installation. It also provides functional outboard-weight. In combination with running left-hand propellers; the model may not require any outboard wingtip weight. There are no offsets built-into the engine mounts or either rudder.

rsv1cox wrote:You are at a point now where you could install your engines and get a ball-park idea of where your balance point is, paint or no paint.  

Our two P-38 models are very close in size but probably quite different in weight.  I think I posted pictures of mine sitting on a scale but I have forgotten what the weight was.  Your model should be much lighter.  

My model balances perfectly at the leading edge of the wing, back about a half inch and it becomes nose heavy but not to the point where it does not fly, circles only.

You might get away with the complexity required of those product engines, pegs, bands, remote fuel tanks and all.  But I would recommend your stunt tanked Golden Bees over them in a heartbeat.  Golden Bees have always been my best running, easiest starting, and most reliable Cox engines.  

Looking forward to April

Bob

Hi Bob, I did get an idea on where the model balanced with product-style engines installed.. but it was far from conclusive at that point. It was a "mock-up" with 3 very heavy wheels on the gear..




The weight in ounces "with engines".. but less wheels, fuel-tanks or control-system.



As usual.. I'm counting on adjusting the models' balance/CG "functionally". One means is through the use of different weight wheels. The 1.375" diameter Perfect-brand wheels (shown) are HEAVY wheels to run on a 1/2A model.. (even with twin-engines)

I will be weighing the model periodically.. and also checking its balance to get an idea of what to expect. It will be interesting.. and I'm not discounting the possibility of running the Golden Bees. I already provided for their mounting if need be. An excessively tail-heavy condition following paint/finish may necessitate their use.

Looking great roddie, balance is about where mine is.  Where are your home-made foam wheel/tires?  Bet they would be much lighter.  

The weight is half of mine which weighed in at about 15.85 oz all up.  I'm seeing a great flyer in your future.  Rock and roll.

Bob

Thank you roddie for the explanation. I am probably the only one that missed it....

rsv1cox wrote:Looking great roddie, balance is about where mine is.  Where are your home-made foam wheel/tires?  Bet they would be much lighter.  

The weight is half of mine which weighed in at about 15.85 oz all up.  I'm seeing a great flyer in your future.  Rock and roll.

Bob

I fab'd-up some of my homemade wheels this afternoon. I had previously CNC routered a bunch of different sizes from 3mm "Dibond"; a rigid material (panel) used in the sign industry. It has a dense plastic core with aluminum facers bonded to each side.

The hub-hole is 1/8" diameter.. because the wheels were routered with a 1/8" endmill. I made a mandrel from a long 5-40 machine-screw and nuts for grooving the plastic-core to fit an O-ring tire. Chucked in my drill-press; I use a 1/8" dia. round rasp to cut the groove.





The larger wheels are 1.375" diameter with the O-rings mounted.

Their weight per pair is 4 grams



and below; the Perfect-brand 1.375" streamlined wheels' weight per pair is 20 grams..



I weighed the model again today with controls installed.. and pretty-much everything except paint and the .5oz. fuel-payload.  

We're at just over 9 ounces.