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Sacrificial Wen-Mac Kingcobra

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Re: Sacrificial Wen-Mac Kingcobra

Post  akjgardner on Sun Apr 02, 2017 6:10 am

Hey Bob , Bernie sells some rubber 1 1/2 Wheels That Are A Real Nice Replacement For The Wen Mac P39. Just incase Yours Are In Bad Shape
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Re: Sacrificial Wen-Mac Kingcobra

Post  rsv1cox on Sun Apr 02, 2017 7:37 am

akjgardner wrote:Hey Bob , Bernie sells some rubber 1 1/2 Wheels That Are A Real Nice Replacement For The Wen Mac P39. Just incase Yours Are In Bad Shape

Thanks,  I hadn't thought about replacing the wheels but that's a possibility.  I have never liked the way they did the main landing gear on these Aira/Kingcobras, very un-scale like and to close to the trailing edge of the wing for comfort.



But, wheels are something that I have plenty of including a set of these very cool inflatable Trexlers.



Depending how this effort turns out, I may have found a different "sacrificial".



While this one may look better, it's really a mess with a badly cracked but repaired wing.  But it does have the engine cowling which usually is missing and a different landing gear and pilot ejection system, the other has one too.  





The V shaped strut goes on the other plane and fits over a pylon inside the fuselage.




Of the five or six of these that I have this is the only one with those differences.  

If I change horses here I will remove the engine cowling and horizontal stab assembly and save the good parts and put the bad ones on the flying junker.  

Bob
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Re: Sacrificial Wen-Mac Kingcobra

Post  GallopingGhostler on Sun Apr 02, 2017 8:14 am

Seems unnatural, Bob, that the rear wheels would be angled so far back. I think it was probably designed such the fuselage was level when resting on wheels. Perhaps a move by the manufacturer, temporarily binding the plane to the box bottom so a thinner profile was obtained by the box to lessen box costs? And over a very long period of time being box kept with model bound by string or tying wire, the landing gear metal wire creped and deformed to a backward position? A key hint may be in catalog photos of the plane.
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Re: Sacrificial Wen-Mac Kingcobra

Post  getback on Sun Apr 02, 2017 8:59 am

Just got around to reading this one and Bob you're doing a really good job on repair for a salvaged old beat up plastic plane , it's looking nicer as it goes ! Looks like all these planes have the landing gear swept back like that ? https://www.google.com/search?q=wen+mac+king+cobra&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwijrLiz9oXTAhXJOiYKHbo6BPcQsAQIJg&biw=1600&bih=770#imgrc=K3d_JbULdBGUSM: Very Happy Huh...
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Re: Sacrificial Wen-Mac Kingcobra

Post  GallopingGhostler on Sun Apr 02, 2017 10:01 am

Bob, I found photos of a mint condition Wen Mac P-63 in E-Bay with box, sold for $214.48 shipping included. Rear Landing gear is stored not installed. When assembled, it sits level. Not saying that rear landing gear leaning back is not the way they shipped, just didn't seem right.

ebay.com: Item# 351688849968 Wen Mac P-63 King Cobra sold 5-May-2016
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Re: Sacrificial Wen-Mac Kingcobra

Post  rsv1cox on Sun Apr 02, 2017 10:15 am

Thanks for that link Eric, I see a few of my pictures there. Also some of Mark's.

That must be one reason for the removable landing gear George, flatter boxing. The early models as I mentioned had fixed inside the fuselage gear. Good price on the one you linked, NIB and including the ejecting pilot.

Bob
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Re: Sacrificial Wen-Mac Kingcobra

Post  roddie on Sun Apr 02, 2017 6:01 pm

getback wrote:Just got around to reading this one and Bob you're doing a really good job on repair for a salvaged old beat up plastic plane , it's looking nicer as it goes ! Looks like all these planes have the landing gear swept back like that ? https://www.google.com/search?q=wen+mac+king+cobra&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwijrLiz9oXTAhXJOiYKHbo6BPcQsAQIJg&biw=1600&bih=770#imgrc=K3d_JbULdBGUSM:  Very Happy Huh...

Ditto.. I just got round' to reading this thread this morning too. My gawwwd Robert.. you have the patience of a SAINT. I wouldn't/couldn't have repaired that elevator. Good job man! I was reading from your first post.. and thinking; Shocked this ain't gonna' be an easy fix.

This post has been an "on and off" afternoon's work. It's a beautiful mild and sunny day here in N. Smithfield, RI.. so I've been "in and out" doing some lawn clean-up and putting the Winter away.. hopefully until next..

I probably would have tried to re-make the whole stab/elev. assembly from balsa and hinging-it together conventionally.. but then there's that centrally-located horn, which would require making a new horn from brass-sheet, and soldering it onto a u-bent music-wire elevator-joiner.



I admire your replicating the original-design.

I'd personally discard the old fuel tank though. No telling the crap that's in there that could clog-up the feed-line or foul the needle. Maybe you could use your moto-tool with a "cutting-disc" to slice-through just the top of the tank to open it up. I'm surprised that the engine can draw fuel reliably from the original set-up. If the tank looks reasonably clean inside.. you could just cut another top-plate of sheet styrene and re-plumb it as the original with plastic tubes.

This made me think of an idea for fuel-tank flushing.. Shocked but I'll post that in a separate thread.

I've never had a model airplane with a tricycle-gear. I can understand your concerns with the main-wheels being so close to the wing's T/E. The model appears to sit "tail-low" That's not necessarily a bad thing. It will assist in lift when you're launching R.O.G. If the nose-gear is angled.. you could adjust the entire gear-angle to raise the model up a bit.. and still maintain the model's angle of attack. Lock the mains in a vise.. and bend both legs so that they clear the wing by a safer-margain. Use a protractor before/after to check/record the angle. Try to match the "stance" when adjusting the nose-gear.

You mentioned wanting to try a launching-stooge. That's something that needs some thought.. for the best application to "this" model. Although I've not built one yet.. a "U-type" stooge that cradle's the fuse; just forward of stabilizer's L/E would be the way to go .. I think. You'd need to study these photos, to understand it's function/construction. You could easily build it.. or buy it from "Brodak" if still available.







Well-worth the effort to build/expense to purchase; as it would serve to launch many a conventional C/L model without the need of a pitman.

My models are all "tail-draggers" that utilize a "pin-link" in some fashion. I've drilled a hole in a tailskid.. added a tailskid with a hole for a pin.. and also clipped a safety-pin or made a music-wire link to fit onto my tail-wheel's gear-strut to engage a stooge-pin.

My Rare-Bear's tail-gear music-wire pin-link..




My Cox PT-19's pin-stooge link..



My Cox Cosmic Wind's tail-skid.. shown with an optional fiberglass window-screen "tab" that can be attached/glued onto the tail. (I used a paper hole-punch to make the hole.. a super-simple link for a tail-dragger..)



Here's Eric's adaptation of the Brodak type.. (I want to make one of these..)




Hopefully.. you'll have a pitman, but I never had one when I was flying regularly years ago. I had to be inventive. Necessity has always been the mother on invention. I'm not claiming to have invented the launch-stooge.. but I hadn't known about them.. prior to making my own.

I like that engine! It cleaned-up beautifully! I'm sure that you'll find an easy-fix for the NVA. You should run that one IMO. Better that the old/brittle prop broke when it fell. That was an accident waiting to happen. Do you have any newer props that are close the diameter/pitch of the original? Maybe a Cox 5d x 3p? You can always ream the hub if the engine's prop-screw is bigger.

Bench-run a few tanks of fuel. Use a graduated syringe to gage the fuel-tank's capacity. Time the runs.. and adjust the fuel-amount to a preferred-duration of flight; taking into consideration "cold-starting/tuning".. and the time taken to actually release the model for roll-out.

I hope that the maiden goes well. What's the recommended line-length? It's advisable to stay within that spec. Make sure that "all" three gear-wheels are free-spinning.. and treat the axles with a drop of light oil. Make that part of your pre-flight.. as well as smooth-operating controls with equal up/down elevator throws.

Short-tank it for the first few flights. You'll feel more comfortable knowing that you won't be committed to keeping the model in the air for an extended-time.. until the engine shuts-down. Just a couple of laps will give you the initial feel of the controls. Increase the fuel-volume as you get more comfortable turning-circles.

It's helpful to focus on the background.. rather than the model. You'll still see the model enough to control it. Your eye-focus is what can bring-on dizziness. Remember this. It will help you.





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Re: Sacrificial Wen-Mac Kingcobra

Post  rsv1cox on Sun Apr 02, 2017 6:30 pm

GallopingGhostler wrote:Seems unnatural, Bob, that the rear wheels would be angled so far back. I think it was probably designed such the fuselage was level when resting on wheels. Perhaps a move by the manufacturer, temporarily binding the plane to the box bottom so a thinner profile was obtained by the box to lessen box costs? And over a very long period of time being box kept with model bound by string or tying wire, the landing gear metal wire creped and deformed to a backward position? A key hint may be in catalog photos of the plane.

Not understanding the reddie George, nothing untoward there, maybe someone made a mistake. I hit the + mitigating the reddie. I'm not understanding the need for this feature here!

Bob
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Re: Sacrificial Wen-Mac Kingcobra

Post  rsv1cox on Sun Apr 02, 2017 6:32 pm

roddie, you read my mind on several points. One was the propeller, I have new Cox grays at the ready.

More later, been a long day.

Bob
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Re: Sacrificial Wen-Mac Kingcobra

Post  GallopingGhostler on Sun Apr 02, 2017 6:41 pm

rsv1cox wrote:Not understanding the reddie George, nothing untoward there, maybe someone made a mistake.  I hit the + mitigating the reddie.  I'm not understanding the need for this feature here! Bob

Oh, I was referring to the nearly 45 degree slant of the rear landing gear toward the wing trailing edge. It looked so unnatural. Back then, the manufacturer was shooting for as realistic a looking RTF as possible, which meant that overall the model would closely mimic the real thing. (Cool factor to an adolescent turning teen.) Observing the fuselage not sit level on 3 gears but sagging a lot in the tail looked as though this was not intended. That is what I was referring to, wondering if rear gear wire needed to be bent so it was straighter, like may be 10 or less degrees to vertical.

It's been 50 years since I last saw such things, and so the gray matter is getting a little dim behind the optic nerves. However, this day and age, I'd probably gravitate toward something like the Midwest .10 - .15 powered profile 33" span P-63 King Cobra, like the one I built in the early 1980's. Probably my speed now due to fumbling fingers and need to move larger than smaller.

Bob, just commenting and meant really to be nothing. After all, beauty is in the eye of the beholder, and as such thus far your repair work looks excellent.
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Re: Sacrificial Wen-Mac Kingcobra

Post  roddie on Sun Apr 02, 2017 8:06 pm

Yea.. the "red/minus" on George's post must have been a mistake. I personally don't use those buttons.. although I should have given MANY "greenies" over the course of time.  Rolling Eyes There's still functions/buttons on this forum that I've never explored.

Bob, grain of salt.. I tend to give WAY more advice than can be digested in a single reading.  tongue When I comment; I feel like I'm there with you.. chewing the fat over a good cup of coffee in the workshop!  Eyebrows
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Re: Sacrificial Wen-Mac Kingcobra

Post  GallopingGhostler on Sun Apr 02, 2017 8:23 pm

Oh, who knows what people sometimes read into a comment. In other forums, I've gotten really negative comments on stuff that was taken in a way that I never intended. Just like like you, Roddie, I don't usually resort to clicking the vote buttons. A few times I've seen someone deep six a user by clicking negative for some not readily apparent reason, for which I counter by clicking positive.

Lo and behold, there is an earlier olive drab P-39 on E-Bay that is in decent shape, Buy Now for $200 + $85 ship. I looked at the photos, and the rear end is sagging just like some of the other photos.

http://www.ebay.com/itm/60s-VINTAGE-AMF-WEN-MAC-ROCKET-FIRING-P-39-AIRACOBRA-COMPLETE-w-box/322457316774


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Re: Sacrificial Wen-Mac Kingcobra

Post  rsv1cox on Mon Apr 03, 2017 7:08 am

I saw that one George, but being used I thought it overpriced. But it is complete and even has the gunsight.

Bid on this one instead:

http://www.ebay.com/itm/used-WEN-MAC-gas-airplane-034-WHITE-BELL-COBRA-034-SELLING-AS-IS-not-COX-or-TESTORS-/112351220053?_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D40130%26meid%3D2f64fedc70f2442db10ae0d03f584ecd%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D112351231007&_trksid=p2047675.l2557&nma=true&si=yBzxwTK%252FbFbo%252FMeC0iXaxXtu8Dg%253D&orig_cvip=true&rt=nc

It was $25 to start and I bid $46. Someone nibbled me up to my max and won it for $47. I surely didn't need another, I'm thinking parts, but what made it attractive was that shipping was free.

I read your "fuel tank flushing" thread roddie. It's something I will try, but not on this repaired tank. I'm afraid it's to fragile to sustain much handling. I managed to glue (red tube plastic) the feed nipple back on and replace the fill and vent tubes with brass heated and plunged into the plastic and sealed with more plastic glue.



The heat method works great as the hot plastic molds and adheres to the brass. But I'm not sure about the feed nipple, necessary as the feed tube goes all the way to the bottom of the tank to ensure most of the fuel is picked up. The heat method just dislodges that feed tube, ok for fill and vent though.





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Re: Sacrificial Wen-Mac Kingcobra

Post  Oldenginerod on Mon Jun 11, 2018 8:09 am

Hey Bob, it's more than a year since your last post on the Airacobra rebuild. Did you go any further?

Rod.
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Re: Sacrificial Wen-Mac Kingcobra

Post  ticomareado on Mon Jun 11, 2018 2:38 pm

I've also got a white Kingcobra with rough incomplete British markings that I need a canopy, pilot and rockets and some replacement rubber for (looks like barn rats chewed mine up) Mine also has this yellowish tinge to it that won't come off with Dawn or alcohol. How can I get it clean? Otherwise it has potential for full restoration. I'm also considering painting it up into a Russian Kingcobra.
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Re: Sacrificial Wen-Mac Kingcobra

Post  rsv1cox on Tue Jun 12, 2018 6:20 am

Oldenginerod wrote:Hey Bob, it's more than a year since your last post on the Airacobra rebuild.  Did you go any further?

Rod.

Hi Rod,

Yes, I finished it some time ago and posted about it in a thread that has now vanished into cyberspace.

I had to paint it due to the half balsa repaired elevator. Turned out pretty good. I did not use the plastic paint pictured, I painted it with Krylon gray.





And Victor, I have tried to reduce the yellow tint on a couple of my plastic models without much success. I think the only cure is to paint them.



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Re: Sacrificial Wen-Mac Kingcobra

Post  ticomareado on Tue Jun 12, 2018 6:31 am

Thanks. Your experience at failure to make it shiny factory white again will probably save me the effort and frustration of trying. maybe some other readers willtell us something we don't know. Now, regarding canopy-- who can vacu-form them for a reasonable price?
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Re: Sacrificial Wen-Mac Kingcobra

Post  rsv1cox on Tue Jun 12, 2018 6:39 am

ticomareado wrote:Thanks. Your experience at failure to make it shiny factory white again will probably save me the effort and frustration of trying. maybe some other readers willtell us something we don't know. Now, regarding canopy-- who can vacu-form them for a reasonable price?

Jim and others here have had reasonable luck forming their own using clear plastic from a bottle or other container, making a mold and using a heat gun. I have yet to master the technique. Smile

Bob
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Re: Sacrificial Wen-Mac Kingcobra

Post  ticomareado on Tue Jun 12, 2018 7:35 am

OTOH, I could just go full West Virginia federal prison workshop on mine like this recent Ebay listing:
\


https://www.ebay.com/itm/wen-mac-gas-airplane-control-line-TEN-BEARS-radical-looking-bell-cobra-/112989438414?_trksid=p2047675.l2557&nma=true&si=NXbQnbxxgKuLnaS0VJI4GlHDowo%253D&orig_cvip=true&rt=nc

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P39 takeoff experience

Post  706jim on Tue Jun 12, 2018 10:33 am

Many years ago when I used to fly U control, a kid came to my flying buddy and I asking if we could fly his Wen Mac powered Airacobra. Back then we used to fly models without any landing gear but this airplane had the three wheel landing gear and we figured we would do an ROG.
Usually, I would just apply full up elevator and trim it out once airborne. Well, this under powered overweight wonder made two complete laps on the ground until I relaxed the elevator to neutral at which point it staggered into the air.
So when you get around to flying your plane perhaps my ancient experience will help you make your maiden flight successful. It was pretty neat having rockets on the plane, but it surely could have used more power to perform a little bit better.
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Re: Sacrificial Wen-Mac Kingcobra

Post  ticomareado on Tue Jun 12, 2018 12:08 pm

The one you "flew" must have had a sick Mk IV or Mk V. I got one for Christmas at age 12 with a hot Mk XI and a 6-4 prop. On 25 ft. lines it would get off in 1/3 of a lap and I'd by half worn out dizzy by the time the thing rat out of fuel. It was also somewhat difficult to maintain smooth level flight with it. Believe it or not, the Turbo Jet with a good Mk V was far more enjoyable to fly for me and could fly on 35 foot dacron lines and do a fairly credible wingover. The Dauntless was a good easy to control slow flyer. I never flew any other Wen-Mac planes, but the Mk XI from the King Cobra wound up on a Golden Hawk and later on a CG Lil Jumpin' Bean and I could fly circles off the other "big boys" in the neighborhood with their "superior" Baby Bee and Golden Bee powered Scientific hollow log models.
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Re: Sacrificial Wen-Mac Kingcobra

Post  GallopingGhostler on Tue Jun 12, 2018 1:31 pm

Interesting experienced observations 706jim and ticomareado on the venerable Wen-Mac (Testors) .049 rotary valve engine. Reading between lines, seems that when they increased compression with a better glow head and minor revisions to porting helped the engine to really perform.

I particularly took note of Ken's recent suggestion in another Cox thread, a low cost way of boosting the older Golden Bee (and Baby Bee) performance was simply replace the cylinder with a Tee Dee twin bypass port flute one instead modifying tank back by drilling out the venturi diameter. Bottle neck was the air-fuel path to combustion chamber.

As a 12 YO I had a Cox Spitfire with Silver Bee engine. I no longer have the engine, over the years through various moves, had boxes "lost" by movers. Interesting engine, a foreshadow of the Black Widow, had twin bypasses, 8 cc tank without stunt filler and vent tubes of the Babe Bee tank back. It took that to haul the heavier plane.

ticomareado wrote:I never flew any other Wen-Mac planes, but the Mk XI from the King Cobra wound up on a Golden Hawk and later on a CG Lil Jumpin' Bean and I could fly circles off the other "big boys" in the neighborhood with their "superior" Baby Bee and Golden Bee powered Scientific hollow log models.

Thanks for the perspective. I've been finding there is a lot of folklore regarding engine brands over time. Sceptre Flight has an interesting article on the lonesome Testor's 8000 reed valve, a hot little engine, definitely no slouch.

A big help is matching power to airframe. The lower power Babe Bee did well with my Sterling profile Beginner Eindecker C/L built light, certainly a lot lighter than the plastic RTF airframes.

I've had more luck to go by my own experiences and observations and make up my own mind as to what works for me and doesn't.
Main thing is to have fun at whatever we do with modeling. Tired w/ Coffee Read Popcorn lol!
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Re: Sacrificial Wen-Mac Kingcobra

Post  Ken Cook on Tue Jun 12, 2018 9:37 pm

The Testor's 8000 wasn't bad assuming the rod didn't break. I believe Wild Bill Netzeband had his hands in the design of that engine. In addition, something that I noted early on was the use of the Nylon case. Funny thing a few years ago when I had to replace my intake manifold on my Grand Marquis. The entire intake aside from the aluminum water crossover pipe was made of what appeared to be the same material.
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