operational cowl flaps made easy
 

This is in my build thread as well, but I thought I would post it here by itself. This is sooooo simple, I can't believe it escaped me all these years. I'm pumped, so I want to share this in it's own thread so it is easy to find. A friend, Wayne Fossil (Solo Props) showed me this, and this is my first try at it.

I broke it down into 12 steps. I'll have (4) posts total.

Here we go.

1. mark the location of each flap on the main cowl

2. carefully cut the entire flap section off leaving them attached to each other for now

3. mark and notch each hinge into the cowl ring (make sure each hinge slides in and out freely without pushing the cowl away from the ring

RE: operational cowl flaps made easy
 

4. glue the hinges into the ring while it is in place (I used Tite Bond for this step as you can be liberal with it and it will not glue the hinge joint itself)

5. I taped the flaps back in place

6. put a drop of oil on each hinge to keep them from accidentally being glued fast

7. glued the hinges to each flap

RE: operational cowl flaps made easy
 

8. ran the control cable around the inside gluing a 3/4" section of sleeve to each flap

9. pulled the cable back out

10. cut each flap loose

RE: operational cowl flaps made easy
 

11. reinstalled the cable

12. cut strips of 1/32 ply to attach to each flap to fill the gap when open.

At this point, everything is tack glued, and I will go back over it all with Hysol epoxy.

Parts of two evenings is all it takes, once you have the supplies. I used Du-bro medium hinges, and a Sullivan control cable set # 515.

For control, I debated linking them to the throttle, but I think I'm going to connect them to the flaps, as I think Wayne does. This will have them open at the correct times anyway.

Fun stuff.:D

RE: operational cowl flaps made easy
 

You sir have gone on my go to guy with a question list, say that ten times fast...lolhttp://www.rcuniverse.com/forum/js/f.../msn/tired.gif
Very nice work, was it as simple as you made it look?

RE: operational cowl flaps made easy
 

Thank you.:D I may not be the brightest guy on the site, but I DID stay at a Holiday Inn Express last night. LOL

Yes, this is every bit as easy as it looks. The thing that took me the longest was notching the cowl ring for the hinges. Took me about an hour to get them perfect.

Now a couple things to consider. Your cowl ring ideally is located at the back of the flaps. I guess this wouldn't be absolutely necessary, but it does make for some nice action without flexing of the cowl. You also need room in the bottom of the cowl ring to mount (2) servos, and they need to work in opposite directions. You can use mini servos if space is at a premium. In the Meister P-47 cowl, this is not a problem.

RE: operational cowl flaps made easy
 

Hats off sir!

You made it happen!

Casey

RE: operational cowl flaps made easy
 

Thanks guys. On this cowl, the flaps, and a ring all the way around the bottom, will get covered with aluminum foil. The top 4 flaps will then be painted OD (and I will 'chip' some paint for affect). The rest of the cowl will get the Black and White checkerboard.

Hope it looks like this when done. It better.:D

RE: operational cowl flaps made easy
 

Ram , great job a couple of questions please . I will now at this to my KMP Corsair "must do "list lol .
1)is there a critical distance on the cowl flap that the yellow push rod retainer is glued example 40% , 50% ect from the hindge point ?
2)Servos operate in opposite direction , are linked by a Y-cable to one channel , or master channel like flaps or throttle ?
3)The ply spacers , are they glued to the medal cable ? I have seen spacers done on a P40 , and the spacers were not glued but slid into pockets inside the cowl flap on ecah side of the opening
Thanks for posting , very cool info made simple

RE: operational cowl flaps made easy
 

Thanks LDM. For some answers, here goes.

1. Yes, the range is from about 30%, nearest the servos, to about 55% at the farthest (top of the cowl). This seems to work best and get the cable ends down to the servos.
2. Servos must work opposite each other (via a reversed servo, servo reverser or computer reversing if you have enough channels), and then mixed to a master. Mine will work together with the wing flaps. If you have programmable servos, this is easy as well.
3. each ply spacer is glued to the back of adjacent flap, except the bottom two. They are glued to the cowl. One flap at the top has no spacer and is overlapped from both sides. Works like a fan.

I'll take some more pictures showing more of these details. Should make it easier to see.

RE: operational cowl flaps made easy
 

Nicely done!

RE: operational cowl flaps made easy
 

Gary, I can't wait to meet you and your airplane in Lakeland this spring! You're doing a fabulous job with the upgrades. I'm also glad I'm entered in a non-competing class from you! Mitch.....maroon and gold Waco.

RE: operational cowl flaps made easy
 

Fantasic detailed explanation of how to get working flaps. LOOKS GREAT too. Ironically your use of plywood to fill the gaps matche the use of fiberglass/plastic to fill the gaps and act as rub strips on some 1:1 installations.

As for operation; on the DC-3 at least they are full open on the ground from start up through the take off roll. Once in the air and at cruise they are moved to "closed" or "float" where airloads through the engine dictate how fare open (not much) they are.

They are closed till AFTER landing to help cool the engine on the ground.

Your plan to link to the flaps is close but not completely accurate in most conditions.

RE: operational cowl flaps made easy
 

Thanks for the info. I don't have any more unused channels on my radio, so I'm making do, till I can afford that new 12X.:D

RE: operational cowl flaps made easy
 

Same here.:D

RE: operational cowl flaps made easy
 

Nicely done and explained with pictures.
I have seen Sam Parfitt do this on alot of his warbirds.
Need to try and do this my H9 47, not sure if I have enough room.

Thanks again for the detail info.

Roger

RE: operational cowl flaps made easy
 

If you want to take it a notch further, check out Oregon Scale Aviation's ThermaCowl.
Here's a description and link at the end:

Where Scale Realism Meets Unprecedented Functionality

ThermaCowl Ultra enables the scale or sport aviation enthusiast to automatically control the opening and closing of cowl or cooling flaps in a scale-like manner. As the engine compartment temperature increases, the cowl flaps open wider to allow further cooling. Because the cowl flap position is controlled by temperature, ThermaCowl Ultra aids in maintaining a constant engine compartment temperature. This provides quicker warm-ups, and fewer lean run flame-outs. This control feature was found on many of the WWII era aircraft, and you will find ThermaCowl Ultra an excellent addition to your scale project to add that final touch of realism.

ThermaCowl Ultra adds the ability to optionally open the cowl flaps whenever the wing flaps (or any other channel you choose) are deployed. This feature allows you to verify correct operation while in the pits, and to demonstrate operational cowl flaps any time the radio system is on.

http://www.oregonscaleaviation.com/R...hermaCowl.html

RE: operational cowl flaps made easy
 

really nice Gary! thanks for sharing. on mine I'm using this to control the cowl flaps:

http://www.oregonscaleaviation.com/R...hermaCowl.html

have you tried it yet? also comes with aadjustable temp sensor. thanks again for the thread.

RE: operational cowl flaps made easy
 

Thanks guys. Yes, I knew of this cowl control, but never had one to control till now.:D If it doesn't require a dedicated channel, it may be an option. I'll take a closer look at it. This would be the bomb.:D

RE: operational cowl flaps made easy
 

Looks Awesome..

RE: operational cowl flaps made easy
 

I took a look at the on-line manual for the ThermaCowl and it looks like you need a free channel. Won't be able to use this unit till I upgrade my radio. Nuts. Someday.[8D]

RE: operational cowl flaps made easy
 

How about mixing the cowl flaps to the throttle? You could have them open below say 1/2 and then proportionally close as the throttle is raised. Mitch

RE: operational cowl flaps made easy
 

I was thinking that as well, but how would you show them off on the ground with the motor running.

RE: operational cowl flaps made easy
 

I'll have to ponder that.

RE: operational cowl flaps made easy
 

BINGO! FAntastic solution!