• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

L-21 Javron

Some fun with the cowling

Top supports installed

image.jpeg

image.jpeg

With the 2" lowered mount the Vetterman exhaust is a little tight
I'm amazed at the quality of experimental parts. This exhaust is a work
of art
image.jpeg

With my poster board mock up. I placed the lower cowl vents
a little foreword to give me some clearance about a 1/2 inch

image.jpeg

image.jpeg

image.jpeg

A few little adjustments and I'll start on the real thing
 

Attachments

  • image.jpeg
    image.jpeg
    201.5 KB · Views: 318
  • image.jpeg
    image.jpeg
    206.7 KB · Views: 306
  • image.jpeg
    image.jpeg
    174.1 KB · Views: 276
  • image.jpeg
    image.jpeg
    204.4 KB · Views: 291
  • image.jpeg
    image.jpeg
    75.2 KB · Views: 298
  • image.jpeg
    image.jpeg
    198.5 KB · Views: 230
avnxtek,
You should increase the amount of belly in your lower cowl. This will give you more clearance with the exhaust and also a larger hot air exhaust at the bottom aft end. You may even be able to eliminate those belly scoops with the use of a lip just ahead of the large opening.
 
Mike made a form out of 2x lumber to press soft 032 into rounded-end scoops. I can send pics if you're interested.

The project looks great. Thanks for sharing.fvXGKHq-0%21sizeoriginal.jpg
 

Attachments

  • fvXGKHq-0%21sizeoriginal.jpg
    fvXGKHq-0%21sizeoriginal.jpg
    498.2 KB · Views: 310
Last edited:
I'll probably do a combination of lower bottom cowl and cowl scoops.
That's the value of poster board lot's of trial and error to go
Thanks for the ideas

pictures are very deceiving lots of space between the lower support and the clamp
When I get to final assembly everything will be positioned for max. clearance for sure




Also rotate that front clamp on the muff to prevent it from hitting the lower cowl support channel. It could tap the channel making you think that there is something seriously wrong with the engine.
 
How do you lower the bottom cowl without changing the nose bowl?

When I made my lower cowl I used mikes advice, and when it’s flat, extend the distance between cowl attachment holes if that makes sense. Drops the air filter scoop down. Most stock cubs the cowl is touching the air box, on round filter cubs


Sent from my iPhone using Tapatalk
 
When I made my lower cowl I used mikes advice, and when it’s flat, extend the distance between cowl attachment holes if that makes sense. Drops the air filter scoop down. Most stock cubs the cowl is touching the air box, on round filter cubs


Sent from my iPhone using Tapatalk

So you mean a little more distance between mounting to the lower support rail on the aft end only, giving a bit more bow to the lower cowl?
you can't change the front or it won't fit the nose bowl
My engine is 2" lower than stock and has thrustline built in so the air box is a couple inches below the lower cowl at least the way I have it now
with my poster board mock up
 
Exactly. My nose bowl is lower below the prop opening than most. That provided clearance for my Vetterman mufflers. The dual scoops in my picture went unused so they morphed into a full width cooling lip instead. My muffler clearance is close to the cowl but so far so good. The only nuisance is reaching the quick drain in between two hot mufflers to drain oil. I can live with that. Scoops should work fine.

What suspension will you use? Beware. Your exhaust will dump right onto your TKs or ACMEs. It's a recurring maintenance issue to remove exhaust residue.
 
I have TK's so that issue has been on my mind Any one make covers for them?


Exactly. My nose bowl is lower below the prop opening than most. That provided clearance for my Vetterman mufflers. The dual scoops in my picture went unused so they morphed into a full width cooling lip instead. My muffler clearance is close to the cowl but so far so good. The only nuisance is reaching the quick drain in between two hot mufflers to drain oil. I can live with that. Scoops should work fine.

What suspension will you use? Beware. Your exhaust will dump right onto your TKs or ACMEs. It's a recurring maintenance issue to remove exhaust residue.
 
Consider moving the lower cowl vents forward another inch or so. You want some room behind them in case you need to add seaplane lip to add cooling.
DENNY
 
I did the same, that little bit makes a big difference in clearance.

When I made my lower cowl I used mikes advice, and when it’s flat, extend the distance between cowl attachment holes if that makes sense. Drops the air filter scoop down. Most stock cubs the cowl is touching the air box, on round filter cubs


Sent from my iPhone using Tapatalk
 
It looks good with paper.
I think I'll go for it with aluminum

image.jpeg

image.jpeg

image.jpegimage.jpeg
 

Attachments

  • image.jpeg
    image.jpeg
    168.7 KB · Views: 227
  • image.jpeg
    image.jpeg
    94.4 KB · Views: 216
  • image.jpeg
    image.jpeg
    218.6 KB · Views: 275
  • image.jpeg
    image.jpeg
    202.4 KB · Views: 466
Last edited:
I'd leave out the bottom scoops at first... run it & see if they are needed... wildcatcub turned out ok without them, just a lip in back..(we had them all made)
 
Using the stock nose bowl the slope on the top cowl will increase and the bottom cowl flattens out. Cutting a relief and shielding that with a scoop may be necessary. Or add domes for clearance and skip the scoops. Or morph domes into scoops. Maximize cooling. Experiment. Improve. Bottom line? Do whatever you want. This is the fun part!
 
Last edited:
The entire project looks great, but I'm super happy to see your new harness. :up Good man.

They are not cheap but strapped in with them you are one with the airplane. A great feeling

I realize that your still in progress. Don't forget to install a support hanger for each tail pipe back to the engine to support the tail pipe from banging on the lower cowl.

Keep an eye on me. I need it. first build right.
You probably noticed that I haven't put any holes in the firewall yet waiting to see where things will be. Heat box won't go where it's supposed to but I think I can move it up about 4" just above where it hits the engine mount and it won't be in the way of anything. And Vetterman sends a great kit with clamps and support rods

I really the look of those seats. Would be perfect in my plane...

Keep up the good work. Gonna be a very nice Cub for sure.

Well they went together better than I thought they might. Pick up a good machine and give it a try
very time consuming and lots of planning but all fun


i probably won't get back to the lower cowling until the weekend (that dam work thing keeps getting in the way of all the fun). Thanks for the suggestions the wheels are turning and will probably end up with a combination of all the ideas
 
but the veterman (clamp)kit supposed to clamp to 'engine mount'..... better to make a brace off engine it self, less vibration....
 
but the veterman (clamp)kit supposed to clamp to 'engine mount'..... better to make a brace off engine it self, less vibration....

The Kit that was sent with my exhaust has a drawing showing a brace from the engine to the exhaust and then to the engine mount in a V. They are not a solid brace they have a rubber hose in the middle
 
.... to the exhaust and then to the engine mount in a V. They are not a solid brace they have a rubber hose in the middle
Make certain that when you finish that there is NOT a solid connection between the exhaust pipe and the engine mount. If it is solid it WILL​ break in less time than you can imagine.
 
More cowling fun

A little layout and cutting
image.jpeg

Fabricate some Vents and a little room for exhaust

image.jpeg

Getting it all together

image.jpeg
image.jpeg

And makeing it all fit

image.jpeg

image.jpeg

image.jpeg

image.jpeg

I ended up up with about 3/8" between the muffler and cowl. Hope that will be enough
I need to add a fresh air scoop for heat and a few more camlocs
its all fun.
 

Attachments

  • image.jpeg
    image.jpeg
    132.8 KB · Views: 288
  • image.jpeg
    image.jpeg
    160.8 KB · Views: 280
  • image.jpeg
    image.jpeg
    107.1 KB · Views: 262
  • image.jpeg
    image.jpeg
    163.4 KB · Views: 264
  • image.jpeg
    image.jpeg
    182.3 KB · Views: 281
  • image.jpeg
    image.jpeg
    168.3 KB · Views: 313
  • image.jpeg
    image.jpeg
    221.9 KB · Views: 307
  • image.jpeg
    image.jpeg
    201.1 KB · Views: 375
  • image.jpeg
    image.jpeg
    223.9 KB · Views: 335
Just Baffling and other Firewall forward stuff

Muffler supports to the engine only they have a little flex should work fine

IMG_2700.JPGIMG_2705.JPG

Started with the Vans Baffling and did some work to get more airflow around #3
Hope that Helps keep it cool

IMG_2696.JPGIMG_2697.JPGIMG_2698.JPG

Next is the Oil cooler Not sure if I want it on the Baffling or mounted to the Firewall with a duct from the baffling
Any suggestions pro's and con's
 

Attachments

  • IMG_2700.JPG
    IMG_2700.JPG
    228.9 KB · Views: 539
  • IMG_2705.JPG
    IMG_2705.JPG
    281.8 KB · Views: 502
  • IMG_2696.JPG
    IMG_2696.JPG
    160.3 KB · Views: 328
  • IMG_2697.JPG
    IMG_2697.JPG
    137.2 KB · Views: 330
  • IMG_2698.JPG
    IMG_2698.JPG
    295.2 KB · Views: 275
Next is the Oil cooler Not sure if I want it on the Baffling or mounted to the Firewall with a duct from the baffling
Any suggestions pro's and con's

I just moved mine from the baffles to the firewall (with 4” SCAT tube feeding from the #3 side) because I kept having to rebuild cracked baffles. Though I’ve seen others that haven’t cracked, but they were braced differently from mine. Looking at my old bracing, it’s likely that it contributed to the cracks by focusing the vibes to an area that was likely to crack to begin with.

Just my limited experience.
 
Back
Top