Snaggletooth Gets a New Cockpit

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For the past year, I've had trash collecting in the canopy of my blue Snaggletooth. I really hated that. This was one of my nicer cockpits. Anyway, It was pretty much decided to simply ignore the trash as it would be a very difficult repair. Also, I wasn't about to need a spiffy appearance for competition judging. Then a couple of weeks ago I took a closer look and found that the damage in the cockpit was far worse than I had imagined. In fact, it had progressed to the point where the pilot and cockpit floor might have broken loose completely and fallen in, possibly fouling the flap horn and locking the controls.

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Snaggletooth had a little more than 500 flight on it and trash was first noticed around flight 350. Now, on closer examination, the pilot's shoulders had chewed completely through the cockpit floor from the pilot shaking from side to side and there were cracks running from the pilot to the instrument panel. I really hated the process for making the necessary repairs. The canopy had to be removed by sanding through about thirty pieces of fiberglass and epoxy which was used to mount the canopy. The canopy was removed in one complete piece but needing replacement anyway. The pilot was reusable as was all of the cockpit detail aft of the head rest.

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I thought that I had taken more than enough care to build a strong and secure cockpit interior. The pilot was modified to contain plywood and a blind mounting nut. The pilot was then secured to the cockpit floor with both glue and a screw driven through a plywood reinforcement under the flooe. Surely, this should have been enough,I thought. Well the 1/16" balsa floor was too thin and too soft a piece of wood. In spite of the underfloor reinforcement, the pilot was free enough to move with vibration and flight loads to begin to chew up the cockpit floor after a couple hundred flights.

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OK, the cockpit floor had to come completely out and the fuselage structure cleaned up in preparation for installing a new floor.

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While I was at it, the new floor would be made from from thicker balsa, 3/32", and have added support with three 1/8" x 1/4" balsa reinforcements added. The middle and aft balsa strips are located under the front and back of the pilot above, and just clear of the underfloor plywood reinforcement for the pilot retaining screw. The forward support is there to simply add strength and vibration dampening to the cockpit floor in general.

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A new cockpit floor was made, filled with sanding sealer and painted black. The pilot was glued and screwed, to the floor again. The pilot/floor assembly was then glued to the new supports with Tightbond to give working time and fill any possible small gaps in the structure. The floor was held in place with masking tape while the glue dried. The white line running across the bottom of the instrument panel is Tightbond which dries nearly clear. This Tightbond was in addition to the glue on the bottom of the instrument panel and top of the cockpit floor. I double glue every seam and intersection in my cockpits to make absolutely sure there will be no gaps or cracks where balsa dust can get into the cockpit from below. I would test a newly installed cockpit with a measured vacuum if I could to make sure the cockpit is absolutely air tight. Yes, initially, there will be some condensation form on the inside of the canopy the first couple of times the airplane spends time in the sun. Its my experience, though, that this moisture will migrate through the wood of the structure during the first few outings and eventually disappear completely, never to reappear. I refuse to vent the cockpit and consider vents simply a pathway for balsa dust to enter the cockpit.

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With the cockpit floor and pilot reinstalled, it was time to turn to the canopy itself. It is necessary to paint the canopy frames on the inside of the canopy. Otherwise, all of the glass strips, epoxy filler and sanding sealer will be visible when looking through the canopy to the opposite side. Paint will block that very unattractive view.

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The way I usually do this is to lay out the canopy frames on the outside of the canopy with very thin strips of masking tape. The canopy is then turned over and the inside of the canopy painted by carefully freehanding the masking strips outside. In this case, though, I had an attractive canopy with realistic frame locations already, but needing replacement. In this photo, there is a new canopy taped tightly over the old and the old canopy frames are being copied through the plastic of the new canopy. With the new frames copied, I was back to freehanding the inside frames.

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With the canopy ready to install, it was time to finish the cockpit. A new instrument panel glare shield was cut from manila folder card stock, painted black, and glued in position over the instrument panel. The cockpit floor was to be left flat black as it represents a hole in the cockpit around the pilot. All of the structure behind the pilot had originally been painted black then lightly sprayed with white to look like accumulated dust. Now the glare shield also had to be "dusted with white" and silver marks added to represent aluminum showing through scratchs. When this was all completed the pilot's goggle lenses were masked to keep them clear and the entire cockpit and contents were given a coat of flat lacquer.

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The rebuilding of the cockpit on Snaggletooth would have been much too difficult if I had to work around an airplane sitting on its gear. The engine was removed and a mounting tool screwed to the engine mounts and to my work table which allowed swinging the airplane from side to side and rotating it through complete revolutions. This way I was able to get up close and work with comfort and convenience on the repair.

Al

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The new canopy was installed with many small strips of fiberglass and epoxy. Over the years, I have slid more than one airplane in inverted and ground the top of the canopy off with never so much as a tiny crack in the canopy mounting. This is a very labor intensive mounting but worth the effort inasmuch as the canopy is also part of the aircraft structure and must necessarily be able to resist stress cracking at the front and rear from flight maneuvering loads.

After the canopy has been fully attached, the areas which are to remain clear are masked off using the freehanded black frames painted on the inside for reference. The canopy was then faired in using SuperFil epoxy putty and sanded to shape.

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With the canopy faired in, it is prepped with sanding sealer, spot filler and when ready, painted silver. On Snaggletooth, many of the markings were determined by the location of panel lines, so panel lines were inked in and used for reference even though some would be subsequently painted over. In this photo the silver is on the airplane already and masked off. This masking is for the blue. Basically, I tried to paint from panel line to panel line to avoid noticeable paint ridges where the new paint stopped.

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In this photo all of the colors are on, panel lines replaced and weathered with silver. All of the panels are weathered with a dusting of black and exhaust stains are replaced where the repair painted them out. This shot shows the airplane remounted to a roll around cart using the same mount for the application of clear.

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Here are a couple of close up shots of the repaired cockpit.

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And a few shots of the completed airplane ready to fly.

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Al

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Which one did you fly at the 78 worlds at Woodvale, UK Al? I have an old Super 8 movie here somewhere with you flying over there. John Tidey from OZ had my camera with him and he had quite a bit of film from that W/Champs. Must put it on DVD soon.

HH

>Which one did you fly at the 78 worlds at Woodvale, UK Al? I
>have an old Super 8 movie here somewhere with you flying over
>there. John Tidey from OZ had my camera with him and he had
>quite a bit of film from that W/Champs. Must put it on DVD
>soon.
>
>HH

Can we pre-order, Dallas?
It was my first WCh and Al's flights were unlike anything I ever saw before.
I was amazed of how the Mustang seemed unaffected by the horrible gusts, while my plane was all over the place.

Bruno

>Can we pre-order, Dallas?
>It was my first WCh and Al's flights were unlike anything I
>ever saw before.
>I was amazed of how the Mustang seemed unaffected by the
>horrible gusts, while my plane was all over the place.
>
>Bruno
>
---------------------------------------------------------------------
Thanks for that info Al.


Bruno, coming over on the 19th July out of Sydney. Will have a look at finding that old reel of film and see if I can get it onto a DVD for you. It must be 15 or 20 years now since I had a look at it.

See you in Landres

HH

UPDATE! Found the film and have run it through the projector and all looks fine there.

Near full flights of Bob G with pipe intact!, Bob Hunt, Al Rabe and Les MacDonald. Other bits and pieces shots around Woodvale site with some of the big(for the day!) Lancaster, a jet dart thing and some other flying maybe at Old Warden before the world champs.

Now to get the thing onto video without too much flicker.


HH

Dallas,

I sure could use one of those too if possible. I have only still photos to remember the occasion.

Al

Al, a copy is yours! I'll run a few off and you can spread it around over there if it turns out clear! That way history isn't lost. Can you PM your address to me.

HH

>UPDATE! Found the film and have run it through the projector
>and all looks fine there.
>
>Near full flights of Bob G with pipe intact!, Bob Hunt, Al
>Rabe and Les MacDonald. Other bits and pieces shots around
>Woodvale site with some of the big(for the day!) Lancaster, a
>jet dart thing and some other flying maybe at Old Warden
>before the world champs.
>
>Now to get the thing onto video without too much flicker.

>HH

Dallas,

The disks arrived yesterday. It was a lot of fun watching that kid flying the Mustang.

Thanks much,

Al

Bruno,

Actually, this semi-scale design does seem to do well in wind and turbulence. I attribute this to these molded Mustangs having a relatively high wing loading. The design uses a small wing and large stiff flaps. These unusually large, stiff flaps operate at large deflections (30 degrees up and down) to provide the lift necessary for tight, buffet free maneuvers. This is the semi-scale alternative to airplanes having larger wings, lower wing loading and less effective flaps. It was a new way of getting the same results with a different looking airplane. Did you see Japan's Hora pick up the handle after the contest and fly a lovely pattern with accurate shapes and bottoms without having flown the airplane before? That was impressive. It also demonstrated the quality of a very good airplane.

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Here's Hora with his first maneuver.

Al

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>Bruno,
>
>Actually, this semi-scale design does seem to do well in wind
>and turbulence. I attribute this to these molded Mustangs
>having a relatively high wing loading. The design uses a
>small wing and large stiff flaps. These unusually large,
>stiff flaps operate at large deflections (30 degrees up and
>down) to provide the lift necessary for tight, buffet free
>maneuvers. This is the semi-scale alternative to airplanes
>having larger wings, lower wing loading and less effective
>flaps. It was a new way of getting the same results with a
>different looking airplane.

I was introduced to your style of CLPA by Paul Tupker, who wrote an article on the Bearcat in a Dutch magazine, probably around 1977.
He also mentioned your Mustang, but no pictures. So actually seeing you fly Snaggletooth was really something. It was even better than what I'd hoped for!
I knew Gieseke and MacDonald were great pilots (seen them at the 1976 WCh -that I possibly missed as a pilot due to exams during the trials weekend).
So seeing them being outperformed by two newcomers on the team proved how quickly the standards were rising.
It's only after reading your excellent postings on this forum that I'm beginning to realize why your airplanes are flying the way they do.
I took the other road that lead me from traditional CLPA designs to the french Beringer style. Just as reluctantly accepted as your approach, but in the right hands just as successful.
When my work on the electric propulsion is finished, I'll be tempted to try some (read: many ) of your ideas, for good windy weather performance seems to be moving into no 1 priority these days.



>Did you see Japan's Hora pick up
>the handle after the contest and fly a lovely pattern with
>accurate shapes and bottoms without having flown the airplane
>before?
>It also demonstrated the
>quality of a very good airplane.
>
>Al

You bet! We (all young dutch pilots (team members & supporters) were glued to the circle.
Henk (my flying buddy and present front man of our team) still tells everybody how flabbergasted he was to see not any sign of Hara trying out the controls,
just take off, level laps and wham, straight into the wingover. Can you fill us in about how you survived that sight? We're still wondering 30 years later...
After the WCh 2006 Bob Hunt and I swapped planes too (we were amongst the first 4 ever to fly electric at a WCh), but Bob intentionally skipped the wingover and I follwowed his example.
Better to get the feel in the loops first than scraping a fin on the tarmac....

Here's what 27 years did to me and my models:

Woodvale 1978:
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France 2005:
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Dallas,

The blue Snaggletooth II is the updated version of the silver snaggletoothed airplane I flew at Woodvale. Aerodynamically, the new Snaggletooth is about the same. The biggest improvement, of course, is the modern engine, in this case a R0-Jett 76. It also has stiffer flaps and an inch longer tail moment to compensate for the heavier engine and stronger flaps.

At Woodvale, I managed a 2954 to Bob Hunt's 2963, a percentage difference of .003. You'd be amazed at the difficulty I have convincing people that this airplane is competitive.

This one isn't too bad for my knock-around beater with 515 flights. The Millennium Cavalier Mustang is bigger and flies a bit better but, for now, I'm beginning to trim this one anew to explore the full competitive capability of this updated version of the silver Snaggletooth.

Al

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Admit it Al, the pilot was just scared to death and was trying to hide in the airframe.

Al, I always enjoy your photo features, always instructive. Thanks again for your efforts to share your techniques.

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"Two step formula for handling stress: 1. Don't sweat the small stuff. 2. Remember that it's all small stuff." -Anthony Robbins

I say what Larry said....I love your photo essays Al...lots of info. Thanks for sharing.

ps. Whatever happened to the rebuild of the Hornet. I was off-line for a bit with computer trouble. Did you finish it and I missed it?

Glen,

the Hornet is on hold right now. This is flying season. I'll get back to it one of these days. Meanwhile I have to keep the squadron all in operating condition.

Last month I noticed Snaggletooth had picked up some fore and aft play in the outboard gear. I was afraid the strut retaining block up at the top of the rib had split. Cutting into the bottom of the wing found the block had simply loosened up from hundreds of long, shock geared, takeoffs and rollouts on my slightly rough flying site. I repaired the retaining block by simply filling the enlarged hole with epoxy and inserting a greased 1/8" wire. After the epoxy had hardened, the wire was removed, the gear was reinstalled, and the hole in the wing repaired.

While Snaggletooth has been down for a new cockpit, I've built two new tanks for it of slightly different designs and installed one of them. While I was tank building, I also wrote a piece of about 20 pages, with photographs, on tank design and construction. I'm not entirely satisfied with that project yet. With improvements, it may show up here. This took awhile to put together, too.

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Two weeks earlier, the Cavalier went over on its nose on launch from its stooge and ran for a half lap with the prop getting shorter and shorter until the engine stopped. The outboard shock gear had a solder joint come loose allowing the gear to rotate and trip the airplane on launch. Luckily, the only damage, other than the prop, was some small scrapes on the large spinner. The damage to the spinner isn't much noticeable and I have a pretty one for later. The cowl wasn't damaged in the nose over. I've got to start doing more thorough preflight inspections.

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That Bolly was one tough prop! This incident could have been much worse.

Little jobs like this keep me busy during flying season. It's amazing how much maintenance is required to keep a couple of fairly active stunt ships in shape. Who's got time to work on the Hornet?

Al

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Al,

So you've repaired two planes. The finishes are still immaculate. As I remember, you use epoxy for finish materials. How is it when you have to patch and repaint? How easy is it to blend the colors? It seems that the repairs are perfect so it begs the question of some information on your finishing techniques when fixing stuff.

Thanks for the information. Makes for interesting reading.

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>Al,
>
>So you've repaired two planes. The finishes are still
>immaculate. As I remember, you use epoxy for finish materials.
>How is it when you have to patch and repaint? How easy is it
>to blend the colors? It seems that the repairs are perfect so
>it begs the question of some information on your finishing
>techniques when fixing stuff.
>
>Thanks for the information. Makes for interesting reading.

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Randy,

What can I say? I use epoxy paints, sometimes with urethane clearcoats. I never rub anything out. When repairing, as in the topic of this post, I begin by sanding enough to complete a repair without adding thickness to the repaired area. The repairs are filled and contoured to the original shape without any noticeable bulges. Next, I decide just how much of the airplane, including the repairs, will be repainted and mask off that area, usually beginning and ending at inked panel lines. The masked areas, not repaired, are given a light sanding to allow "tooth" to the paint recoat. Repaired areas are painted, usually with an airbrush, with serious attempts to minimize the weight of material added. Minimal coverage is my goal as gloss isn't an object. Gloss will be restored when the clear is added to protect surface details, mostly ink. This time there happened to be no problem with color matching. I still had more of the original blue and silver. I did have to make more of the brown exhaust using red, yellow and some left over Cavalier olive drab (which is red, yellow and green). I seem to make all of my colors from red, yellow and blue. I mix some using the colors I think I will need then add more of which ever color it seems to need more of, then do it again and again until it looks OK against the airplane paint. This sometimes results in dumping some of the accumulating paint as the tinting process continues to avoid using large quantities of the additional tints. There is no real trick to it. It is a simple matter of adding one color or another until the result is close enough to be usable.

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I have made major repairs to many airplanes which were damaged during intensive practice. It is simply the cost of flying a lot in a very competitive mode with adverse winds and the need for consistently low bottoms. Airplanes will be broken by use. One must simply decide whether they are worth repairing.

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Al

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>
>The new canopy was installed with many small strips of
>fiberglass and epoxy. Over the years, I have slid more than
>one airplane in inverted and ground the top of the canopy off
>with never so much as a tiny crack in the canopy mounting.
>This is a very labor intensive mounting but worth the effort
>inasmuch as the canopy is also part of the aircraft structure
>and must necessarily be able to resist stress cracking at the
>front and rear from flight maneuvering loads.

I used to pull all of my own canopies but now get them from Sparky at [email protected]. Sparky copied my canopy molds and is able to supply Snaggletooth Mustang, Classic Bearcat and BBFB Bearcat canopies made from PTEG. His prices are quite reasonable and the quality is really nice.
>
>After the canopy has been fully attached, the areas which are
>to remain clear are masked off using the freehanded black
>frames painted on the inside for reference. The canopy was
>then faired in using SuperFil epoxy putty and sanded to
>shape.

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>
>Here are a couple of close up shots of the repaired cockpit.
>
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>
>Al

Usual great stuff!
Realy glad to hear you are flying a lot!

Now a question (you hear em every day).
Noticed the green (lime ) masking tape.
Something new?
Seems to me there is a difference in tape;especially tack.
Thanks

Charlie,

That green tape is Scotch 233+ from an auto paint store. It seems to work well with good tack when painting cars. It doesn't work too well on stunt ships with any exhaust residue left in the paint. A lot of clean up is required to get it to stick. Other than that, it works OK. I try to use professional sources when selecting painters tape.

For building I like the cheap stuff from Harbor Freight. It sticks to bare balsa better than anything else I've tried but the tack may be too much for painting.

Al

Al,
You sure have a knack for making a really nasty job look easy. Maybe that's what real craftsmanship is.
Thanks for the pictures.

Randy C

Hiya Al,

Cant wait to get home and start building again!! Reading yours and other peoples' threads on their projects keeps the flame going. Very interesting and informative discussions! Hope to see you at the field next summer.

Next summer will be short though, Around June-July the 4th Infantry Division HQ and 1 BCT will be moving to Ft Carson, CO to join the other division's BCT's (brigades for those who werent around for the remodulization) Heard allot of good things about the Colorado Springs area....except for the extreme changes in altitude (around 5500 MSL or so). Any discussions you may have on keeping models light would be very useful!

Thanks again!!

Ft Carson was where I was discharged in 1967. The town is beautiful the post was the reason I left the Army. I hope it has changed. After all it is only 40 years ago. LOL

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>The white line
>running across the bottom of the instrument panel is Tightbond
>which dries nearly clear. This Tightbond was in addition to
>the glue on the bottom of the instrument panel and top of the
>cockpit floor. I double glue every seam and intersection in
>my cockpits to make absolutely sure there will be no gaps or
>cracks where balsa dust can get into the cockpit from below.
>I would test a newly installed cockpit with a measured vacuum
>if I could to make sure the cockpit is absolutely air tight.
>Yes, initially, there will be some condensation form on the
>inside of the canopy the first couple of times the airplane
>spends time in the sun. Its my experience, though, that this
>moisture will migrate through the wood of the structure during
>the first few outings and eventually disappear completely,
>never to reappear. I refuse to vent the cockpit and consider
>vents simply a pathway for balsa dust to enter the cockpit.

There have been five outings now since the cockpit was repaired and canopy replaced. So far, there has been no suggestion of condensation (or dust) on the inside of the canopy. Admittedly, I fly mostly in the evenings with just time enough for five of six flights before dark. By the time I get to my site the pit area is already in shadow from trees adjoining the circle from the West. I expect that whatever house humidity was picked up during the repair is already leaving and think there is a good chance that condensation will never show up on a really sunny excursion. It seems that with each outing, sunny of not, that the likelihood of condensation appearing is lessened until I reach the point of any condensation being extremely unlikely.

Al Rabe

I always admire cockpit detail. Sorry, guys, but solid block canopies painted just don't have much appeal.

One recent semi-detailed interior on my Hurricane stunter was fully sealed to prevent balsa dust from migrating inside, But after a few weeks I found an extensive spider web inside the canopy. Bruce Hunt took a photo of the canopy (and the spider) and it was published in SN.

Since I was so careful to seal the cockpit, I can't get in there to evict the spider. I don't know how he (she) got there, and nothing I can do about it!

Floyd in OR

Thanks Al.