I have been given a TF P-51 Gold Edition kit to build the B model and I wish to do a little cosmetic work to make it look like the A-36 Apache as well as add functional dive brakes to the wings.

Rather than reinvent the wheel, I thought I'd ask in here first to see if anyone has already rigged up the mechanism for the dive brakes in
this plane.

So, are there any working examples out there for me to reverse engineer??

Thanks

Cool - I never knew this plane existed until I Google'd it. If you have no luck with the dive brakes, look in scale sailplane forums, as some older sailplanes used similar mechanics for their spoilers.

Good luck with the build,

Cam

Hey Cam,
I have been looking at the images I can find on the intardnet and think that I can rig up a set on my own to use for developing the final working versions to go in the plane.

I have noticed that the lower brakes open swinging down and forward as the uppers swing up and aft.
I think this may cause a balancing force between them that will help keep the servo loads reasonable.

tommy gun a 36 great plane to build. although i didnt do that one i did design and build an a model mustang the model right after the a 36. i had kicked around the idea to do the 36. look carefully at the difference between the a 36 and the b model mainly the scoop on the a is on the top of the nose and the lower scoop is just a little different. just depends on how scale you want to go. if you like look at my profile and look at the pics that i have good luck with your project it will certainly draw some attenetion please post some more on this.

Hey Bmodelflyer,
I recognize that you fly at Woodland/Davis Aeromodelers.
Here is my Dora from last year at their Wings of Victory.
http://www.youtube.com/watch?v=TbY658zhHw8

I am not going to use a set of calipers and micrometers to make the conversion from the P-51B to the A-36.

I will be using "TLAR" for the most part.
I will probably be working on the dive brake design long before I finish the airframe out.
One of the previous owners of this kit had built the plane to the point of sheeting the wing and then stopped.
This makes it perfect for me to figure out how to fabricate the dive brakes.

Tom Freidkin's A-36 Apache was located three miles South of me for years. Here are a few dive brake and a few other area images to give you some 1:1 real world close-ups for your conversion. Its not a perfect doc set, but then again...it was free : )

i totaly agree i like to build just as scale as i like, sometimes close is good enough for me.

Tommy I would touch base with Monty Welch in Vacaville. Monty and Kim Lines from Vacaville and members at Woodland build matching A-36's about 10-15 years ago. They both had working dive brakes. If I am not mistaken I think Monty has his still hanging up in the shop. He might get you pointed in the right direction or at least let you know what might not work. His RCU handle is Simley Jack send him a PM.

GREAT STUFF , T Gun the A-36 LOOKS tough , there cant be many of those left,how much of a big deal is it to convert
the B model ? it looks like the nose is the biggest deal

The one I posted photos of was the only flying A36 for many years.
However there were two others in restoration to flight status in the
works. The "Mustangs Mustangs" web site would probably have an
update available on their status and possibly a photo session of their
scheme.

There is/was an OD Green one in Dayton. It however is/was far from
flight status as are most of what's in the USAF Museum.

I have not seen Tom's since it was taken to Chino where it was to be
worked over and move into an onsite hangar with many of his WWII
aircraft.

If anyone wants my complete image library for Tom's A-36 you need
only go to ScaleAero.com and the Builders section will have a launch
button for two photo areas. When the page for the Apache opens and
you click on any image it will enlarge and you can right click to save it.

Thanks FM!
Thats exactly what I need.
I had seen some but not all of these images on the web.
Are there any images of the brakes deployed?

LPMcQ,
If we are thinking of the same Monty, he is the guy that runs or helps to run the WOV at WDAM.
He seems a great guy and I will give him a shout. Thanks for the heads up.

WR,
The main things I am looking at changing are the wing for the brakes, obviously, and hard points for the bombs.
The Lower cowl to give it that "Allison" look, and the upper cowl for the induction air scoop.

I am thinking I may build the dive brake assy's outside the wing as a separate component to then drop into the wing structure before sheeting. Not sure on this yet. Just thinking about it.

Thanks again all.

All the diver brakes on A36's were eventually locked closed because of the problem it poised with aileron control and buffeting it created for the wing. Its going to be simple to replicate as you need only place a plate between the rib at the level of the skin on the top and bottom. Attach an aluminum bell crank turned sideways and drive both top and bottom brakes from a single servo in the center of the wing. Why a single? Well...two might not load up equally and result in a problem of no aileron control.

The cowl alteration will leave you with an exposed two cycle or four cycle head unless you use an RCV and its probably the best to use because it affords more torque for the three blad prop at such a small diameter.

Hey again FM,

I have read literature that says the wiring shut of the dive brakes was not an all encompassing fix and that once the issues were corrected, they allowed the use of the dive brakes to very good effect.

Also I don't mind a bit of engine sticking out of the cowl and will be using a YS 1.10 when I do get to that point.

There are paramount differences in the fuselages of the Allison powered Mustangs as compared to the Merlin powered B and C variants. The nose is the most obvious but the radiator is also entirely different and the whole of the fuselage is narrower in depth. Depending on just how accurate you want the conversion to be it could range from not much of a big deal to a very substantial re-design of the entire structure.

There are issues which lend themselves to scale which are not exactly worth the price of correction at the size of model you are building. I would consider a 1/5th and above subject needing more fidelity to scale than what is being portrayed in your scale project. As a judge I would cast off the slope documented in a series of photos below because it is difficult to see from 15 feet away.

There is a desidely pronounced slope to the backbone of the A36 which is not the case in other airframes of the NA family developed over a very short period of time. Below is a photo to document that fact. Its not in one's best interest to follow down the narrow pathway in persuit of the documentation beyond this photo to assert that this in fact is the case. A photo serves to prove it without further investigation.

Below is the pronounced slope of the A36 backbone...

Additional documentation in support of enhanced slope of A36 backbone.

WOW! I wish I would've run into you guys sooner. I'm currently finishing an A-36 converted from a 1/5 scale Pica kit. I plan to test fly it next weekend, all I have left to do is hinge and hook-up the linkages for the dive brakes. Tommy Gun, I will post pics of my linkage system once I get it installed and working. It was based on a two servo set up, one servo in each wing driving the top and bottom brake. I found that this set-up allowed the dive brake to flex when deployed, two additional servos easily fixed this issue.

Oh yeah, my model is finished in the colors of Tom Freidkin's A-36. Only difference being, I wanted to do a natural metal finish versus the painted silver. I wish I would have had your pictures about a month ago when I started working on the markings.

I've had those photos in the Walkaround section of ScaleAero for many years. Its got some holes which fell victim to several server crashes but for the most part is intact. Tom's A-36 is actually a composite rebuild from multiple airframes. Its no longer here in Houston. It along with others Tom had here moved to Chino with his many others. His hangar in Chino can be seen online.

Almost forgot to post this...Tom's A-36 is painted silver, not natural aluminum to protect it. Don't know what the current finish is since it was being stripped down to bare essentials and reassembly. I'm guessing its still painted considering the rarity of the bird.

Note the hinge direction of the dive brake on top of the wing vs that of the dive brake on the bottom of each wing... It opens 180 degrees out from the opposite side of the wing. Can you imagine the pressure against the top dive brake? I can imagine this could become problematic and be a constant maintenance point... I took a moment to point to the hinge point of the top brake.

Its interesting you made your dive brakes functional. I understood they were of little positive influence and were wired shut by ground crews to prevent their ill effects.

Now, having stated that, I revisited resources to provide a back-up of what I was saying someone else claimed... : )

Never ever, say there is anything definitive about military aviation and traits of any one of them... Visiting here will provide a statement from the father of a documentarian and some additional opinion as to the origins of the wiring statements... http://www.aerofiles.com/divebrakes.html

As I understand it, his A-36 is currently being re-restored. When it came back from the Flying Legends show in Duxford, it was never reassembled, just stored till work could begin on it. I don't know how they are planning to refinish it. Personally, I'd like to see it in a war-era scheme (OD over Gray). Several A-36's based in Siciliy completed 200+ missions, one in particular had the mission marks starting at the nose and running all the way down the left side. Might be interesting to see full-scale.

Wind pressure on the dive brakes shouldn't be an issue. There is a rod that connects the top and bottom brake within the wing. As the top brake is is opened, it pushes the bottom brake open. The wind helps open the top brake, and pushes the bottom brake closed. Since they're linked together, the wind pressure on both brakes should cancel out leaving little load on the hydraulic cylinders driving them; or in the case of the model, the servo. The "Allison Mustangs Walkaround" book by Squadron Signals has a good diagram of this system.
I chose to make the brakes operational, because I like models that function the same as the full scale. If they prove to be problematic, or a maitenance issue (both likely) I simply won't deploy them. And this way, all the static pictures can show them open helping distinguish the model as an A-36, not a P-51A.

Since Tom loves his fighting parrot logo I'd guess it will remain on the A-36 instead of an authentic scheme being applied to it. I agree, this should be in the ANA OD which appeared on the A-36's in service. I know its dull, drab and less than the spectacular, however it is authentic vs the boxing birdie : )

Many of Mr. Friedkin's warbirds no longer carry his trademark boxing bird logo and, with the rarity of the A-36 as well as the trend towards authenticity, I would not be a bit surprised to see the A-36 emerge in a much more authentic finish than it had previously.

Apparently I lied. I didn't intend to, but I did. My dive brakes are not functional, as of yesterday. When I tried to instal them and get all the linkages connected, I ran into a problem with clearance. One of the rods linking the top and bottom brake was interefering with the servos driving the brakes. End result, I couldn't get the top brake to close tightly. I was very nervous about that top brake being blow open by the wind, so I decided to abandon the idea of functioning brakes and screwed them down. I did take some pics before I locked them down to give you an idea of what my set-up looked like. Maybe they will help you avoid the problems I ran into.

By the way, Tom's "Boxing Parrot" was the emblem for the Eagles Squadron; the RAF's squadron of volunteer US pilots prior to the US entering WWII. What a cool emblem to have as a personal logo. The bird can stay, just paint the plane O.D. over gray.

According to the National Museum of the U.S.Airforce, it's a "boxing eagle", and interestingly enough it was drawn by Walt Disney's artists.

EDIT: link
http://www.nationalmuseum.af.mil/fac...et.asp?id=7883

Test flew my A-36 this morning. Sweet flier! Little slow with the 3-blade, but very stable.

Hi WBP,
Thanks for the shots of your dive brake assy.
It looks like you did a fair bit of engineering there.
I hope you are able to figure a work around for your linkage.
Nice job!

Here is my first draft of what I am planning.

This would use a small retract servo at the outer and inner end of each dive brake bay.
I have not yet worked out the geometry for the linkage, but it looks workable to me.