Re: P-38 Lightning-Roddie style..

NEW222 Mon Feb 19, 2018 3:00 pm

Those wheels are absolutely amazing, and well thought out. Even without a CNC, I think they may be something that one could make themselves with a drill press. Simple yet very good looking.

rsv1cox Mon Feb 19, 2018 3:04 pm

I like those wheels better than the foam wheels/tires that you have shown here before, but as you know they would not look right on your P-38. The foamies would look better, but there are military style wheels that would be "perfect" but at a moderate weight penalty.

Try the Golden Bees instead and check the weight. You might even lose some.

Bob

roddie Mon Feb 19, 2018 4:09 pm

rsv1cox wrote:

Try the Golden Bees instead and check the weight. You might even lose some.

Bob

The Golden Bee's are just slightly heavier than the product-configured engines.

P-38 Lightning-Roddie style.. - Page 5 Weight12

P-38 Lightning-Roddie style.. - Page 5 Weight13

There's also another important factor.. see the photo below..

P-38 Lightning-Roddie style.. - Page 5 Weight14

Much of either engines' weight is concentrated near the center of the crankcase. Because of its' 8cc integral fuel tank; the Golden Bees' crankcase is approx. 7/16" (11mm) forward of the product engines' when mounted to the firewall.

Fuel-weight will be close to the same at 7.39cc's vs. 8cc's.. but the 7.39cc tank is positioned well-aft that of the 8cc integral tank on the Golden Bee. If the theoretical CG for this model falls on the wings' leading-edge at the nacelles.. then the external tanks will "straddle-it".. which would be ideal.

**944_Jim** Tue Feb 20, 2018 9:04 pm

roddie wrote:
rsv1cox wrote:...The way that Jim did his was so much better. I hope you kept a picture of Jim's...
Bob

...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

I hate to crash the party, so I'll be brief.
First, Roddie...great model. I've been enjoying watching this one come together!
Second, Bob and Roddie...aw-shucks! I didn't think my attempt at that BHM kit made any impact. You two floored me by bringing it up out of context.
Third, yeah tank placement IS an issue. I had a pair of 2/3-1 oz tanks for it. I even went through great pains to remove the bottom vents in order to place the tanks on top of the wing. That was an excersize in futility!
I couldn't get the engines running at the same time. Once one engine got running, it would flood out before getting the other running. My son and I smoked a spinner trying my Hornet starter on this one. At one point I thought I ruined a basically new Norvel .074! Once the worst impacted engine was separated from the goobered tanks, it ran fine (phew!). The finish damage caused by ripping off the fuel tanks took a bit work to repair...just don't get too close to notice.
I will be making some 3/8 oz or 1/2 oz tanks, and mounting them UNDER the wing...just below the needle/venturi height. It may require taking advantage.of muffler pressure...but at least she shouldn't flood any more.
Bob, did you fly your Mossie yet?
Thanks, now back to our regularly scheduled P-38 news...

roddie Sun Feb 25, 2018 1:56 pm

I just didn't like the way my bellcrank was positioned. The throw-ratios were off due to my not locking elevator-neutral when I drilled the bellcrank-pivot/hole-location. There's no clevis for adjustment when using two L-bends on the pushrod. I like the idea of one less failure-point in the controls.. but it has to be done correctly. What I had would not give equal up/down elevator deflection. Doh!

.. bogus.. I had to fix it.

A simple elevator "neutral-lock" using two craft-sticks and binder-clips allowed me to proceed in correcting the problem. The bellcrank mounting-screw is removed to expose the "eye" in the bushing. I then re-position the bellcrank (pushrod installed) with both arms equidistant from the boom/nacelle and use a small "awl" to mark the new hole-location for drilling.

P-38 Lightning-Roddie style.. - Page 5 Dsc05338

A more forward location yielded more needed "down" deflection.. and moving the pivot away from the boom increased the amount of available control-throw.

P-38 Lightning-Roddie style.. - Page 5 Dsc05337

There's always more to this, than one can anticipate.

Marleysky Sun Feb 25, 2018 2:04 pm

iDK, but I think having more “up” than “down” is a good thing, especially when you have gravity providing a bunch of “down” all the time. Huh...

rsv1cox Sun Feb 25, 2018 2:36 pm

What Rene said.

Locking the elevator as you did roddie is my SOP. Only way to set up the bell crank true.

Unless your camera distorts, it looks like your control rod is bowed at the guide, an easy fix. I am still an advocate of a centrally positioned rod on the elevator ensuring an even application of torque to both ends of that important control surface. A thicker rod would reduce any tendency to bend. Have you ever seen the thin rods used in most plastic models.

I could center my control rod in my P-38 due to the hollow fuselage and I did use a stronger rod and noticed no problems in control. More difficult in a profile roddie but possible. Still, were I you I would ignore this advice and do it your way.

Either way I think you have a winner.

Bob

roddie Sun Feb 25, 2018 3:06 pm

rsv1cox wrote:

Unless your camera distorts, it looks like your control rod is bowed at the guide

Bob

You're correct Bob. I didn't see the "bow" being an issue. If anything; the rod will have even less tendency to flex if slightly bowed. It could cause wear to the "fairlead" after a few-hundred flights... but if this airplane fly's that-many "missions"... it will have lived a fairly long-life.

roddie Sun Feb 25, 2018 4:27 pm

Marleysky wrote:iDK, but I think having more “up” than “down” is a good thing, especially when you have gravity providing a bunch of “down” all the time.

Yes Rene.. that is true.. especially with my zero-incidence sheet-wing producing zero-lift. When flying "level"... there is a considerable amount of down-force acting on the model. With any luck; this model will turn with predictable-precision.. within the boundaries of an average line-length.

roddie Sun Feb 25, 2018 6:12 pm

I have voiced my opinion on the usefulness of the 1/2A spring-style wheel-retainers before. Carl Goldberg models and Sig Manufacturing "had" offered these in the past.. but now; unfortunately.. you'll need to hunt for them. Bernie (Cox International) had sourced a NOS supply of them not too long ago.. and may still have some packages.

P-38 Lightning-Roddie style.. - Page 5 Goldbe10

Hear me out.. these spring-collars are designed to fit 1/16" (.062"/1.6mm) piano-wire.. and provide a lightweight/reliable friction-collar that will assist in a myriad of modelling needs.

I am using these with this P-38 model. The elevator-pushrod is 1/16" piano-wire. It utilizes two "L-bends" which must be retained. Using a series of flat-washers with a spring-retainer; a linkage can be made to work with reasonable precision.

These photos will show where I have used these spring-retainers in the control-linkage of this model.

P-38 Lightning-Roddie style.. - Page 5 Dsc05339

The above photo-example shows a 1/16" piano-wire pushrod being retained in a Sig 1/2A Nylon bellcrank. Take a close look..

P-38 Lightning-Roddie style.. - Page 5 Dsc05340

The spring-retainer establishes a "clearance". That's basically the beauty of using it.

Here is where I use one on the elevator horn...

P-38 Lightning-Roddie style.. - Page 5 Dsc05341

I'm just a novice flyer.. but I like to build precision into my flying models. It doesn't cost much...

roddie Sun Feb 25, 2018 9:44 pm

Next-up was the nose-gear. I wasn't happy with what I initially designed. The nose-gear was designed around a "smaller-diameter" .045" piano-wire, having a double-wound coil to act as a "shock-absorber". The .045" dia. wire-size complicated using standard-size axle-bushings.. so I've upgraded the nose-gear strut to an .062" piano-wire assembly which will utilize a "single" shock-absorbing coil.

P-38 Lightning-Roddie style.. - Page 5 Dsc05343

This should provide for a heavier-duty nose-gear.. without too-much of a weight-penalty. I'm not sure about wheels yet......... As I've said countless times before; wheels can help to finish-balance a model-airplane. I have several options open to this model. We'll see how she balances after she's got all her flying-clothes on..

Marleysky Mon Feb 26, 2018 8:40 am

Hey! Roddie, I found a front tire for you........Fred Flintstone style.

P-38 Lightning-Roddie style.. - Page 5 D3cf8e10

rsv1cox Mon Feb 26, 2018 8:59 am

Now that is funny Rene. What's the back story if any? Brit, Aussie, Kiwi?

I like those spring retainers roddie.

Marleysky Mon Feb 26, 2018 10:03 am

rsv1cox wrote:Now that is funny Rene. What's the back story if any? Brit, Aussie, Kiwi?

I like those spring retainers roddie.

It’s a Woodyear tyre, made from roundwood. Used to support aircraft moving off the production line, whilst waiting for the real rubber tires to arrive.

(Nah! I just lifted the image from “woodworking for beginners “ Facebook page.)
https://www.facebook.com/groups/1761759164151923/permalink/1992964531031384/

Just for giggles. lol!

My apologies to Roddie for hijacking his thread.

OVERLORD Tue Feb 27, 2018 4:44 am

Nice build. I like your detailed pictures. Curious to see the paint job!!

Marleysky wrote:

This has been done before. I remember seeing a German WW1 Albatros in the aircraft museum in Brussels. That had original wooden wheels on it. This was because of the lack of raw materials.

roddie Tue Feb 27, 2018 10:50 am

Thanks for the comments guys. Thumbs Up

No worries about the "Woodyear" wheel Rene.. It never hearts to inject a little humor into a project.. especially where I tend to get OCD/anal with my methods. Laughing

Actually... I just sourced some more wooden wheels.. but at 1.125" diameter; I think they're a skosh too small for this model.

P-38 Lightning-Roddie style.. - Page 5 Dsc02510

fredvon4 Tue Feb 27, 2018 11:00 am

Roddie... find a way to eliminate the BOW and resultant drag at the fair lead.... Trust me

roddie Mon Mar 05, 2018 2:26 pm

fredvon4 wrote:Roddie... find a way to eliminate the BOW and resultant drag at the fair lead.... Trust me

I wasn't going to pay any attention to this.. but Phred scared me into it.. Doh!

With my luck, I would have a control-system failure that could be traced-back to the bowed-pushrod.

A new/longer fairlead was the easiest fix.

I didn't want to cut the original fairlead off.. so I figured I'd try heating it with a soldering-iron to melt the glue (CA) which worked.

P-38 Lightning-Roddie style.. - Page 5 New_pu10

.. next came fashioning a new longer fairlead from a slightly larger safety-pin. I cut off the clasp and squeezed the two wire-legs together near-parallel using needle-nose pliers. I then clamped the part in the jaws of some small locking-pliers.. and proceeded to chisel-point the two legs using a sanding-block. I roughed-up the ends to better retain glue, using a riffler-file.

P-38 Lightning-Roddie style.. - Page 5 New_pu11

The locking-pliers were also used to drive the new fairlead into the balsa.. using my work-table as a back-stop.

P-38 Lightning-Roddie style.. - Page 5 New_pu12

P-38 Lightning-Roddie style.. - Page 5 New_pu13

I feel better having attended to this.. it was bugging me. Now I can hopefully pick up the pace.

rsv1cox Mon Mar 05, 2018 3:11 pm

We all feel better roddie. Wouldn't want a small imperfection spoiling an otherwise perfect model.

Bob.

roddie Mon Mar 05, 2018 3:20 pm

I had left the holes in the blind-slat/wing.. because it afforded a place for a hanging-hook to keep the model up-high/safe from a balsa-chewing kitty.. Doh!

You people following this build were probably wondering when and "if" I was ever going to plug them. Well.. today was the day.

P-38 Lightning-Roddie style.. - Page 5 Pluggi10

P-38 Lightning-Roddie style.. - Page 5 Pluggi11

I like this type of Elmers wood-filler. Last use was a couple years ago.. (this tube) The filler will harden in the nozzle with non-use.. but easy to clear-out.

roddie Mon Mar 05, 2018 3:24 pm

rsv1cox wrote:We all feel better roddie. Wouldn't want a small imperfection spoiling an otherwise perfect model.

Bob.

You're too kind Robert.. Smile

Finish-work/painting is not my forte'.. and I assure you it will be far from perfect after that's done.. Laughing

rsv1cox Mon Mar 05, 2018 3:33 pm

roddie wrote:I had left the holes in the blind-slat/wing.. because it afforded a place for a hanging-hook to keep the model up-high/safe from a balsa-chewing kitty..

You people following this build were probably wondering when and "if" I was ever going to plug them. Well.. today was the day.

]

I was hoping rocket pods or bomb/fuel tank hangars. Smile

roddie Mon Mar 05, 2018 5:20 pm

rsv1cox wrote:

I was hoping rocket pods or bomb/fuel tank hangars.

............. you just gave me an idea Robert! I'm not planning on turning this airplane into a "Woonsocket Rocket".. ( Laughing

.. only someone from Rhode Island might get that joke..) but some simulated-armament would be appropriate. I'll be spending some quality-time with Lynne this evening.. but check-back for some subtle additions soon...

rsv1cox Mon Mar 05, 2018 5:38 pm

roddie wrote:
rsv1cox wrote:

I was hoping rocket pods or bomb/fuel tank hangars.

............. you just gave me an idea Robert! I'm not planning on turning this airplane into a "Woonsocket Rocket".. ( .. only someone from Rhode Island might get that joke..) but some simulated-armament would be appropriate. I'll be spending some quality-time with Lynne this evening.. but check-back for some subtle additions soon...

Hmmm............ Construct your existing fuel tanks into pods, feed engines from them. Max cool.

P-38 Lightning-Roddie style.. - Page 5 P-38_t10

roddie Tue Mar 06, 2018 12:37 pm

rsv1cox wrote:

Hmmm............ Construct your existing fuel tanks into pods, feed engines from them. Max cool.

That would be "Max cool" Bob! Balloon-tanks might work for replicating those. If it could be done in a non-complicated manner and provide consistent/reliable performance, I'd be all for it. What I'd "want".. would be a central-fill for both tanks.. having "tee'd" bleeders on both feed-lines for purging air from the system; sort of like bleeding air from hydraulic brake-lines. That sounds complicated... but it would be an interesting experiment. The bleeder-tubes would need to dump air/fuel into small recovery-vessels to avoid waste and preventing raw-fuel from being dumped onto the ground. The three open lines would be "capped/plugged" following the absence of air (bubbling) in the recovery-vessels.. which would result in a closed-system.

Fun to imagine.. but would it work?

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P-38 Lightning-Roddie style..