Typical T-6/BT-13 Modern Radio/Intercom Installation

[VCS1]

Hello All
Working on a restoration of a Vultee BT-13 to orginal condition with all the military radios, conduit flying hoods ect. All this stuff is neat, but the aircraft still has to fly in modern airspace.

As a result, I need to plan a basic VFR, class C airspace radio and intercom system for this aircraft that I can tastefully "hide" amongst all the original equipment, but still be accessible and safe.

The BT-13 is a typical tandem two place trainer aircraft and I am sure there multiple variations with Stearmans, T-6's, T-34 ect that have had modern radios installed.

The most common response is to just use a handheld radio and leave everything alone. I am not a pilot, but I think have an installed system would be safer and lend to better cockpit management. I don't want to install anything fancy or cutting edge like glass cockpits either. Just something simple, safe and basic.

I appreciate any feedback from pilots, mechanics that have designed/installed similar systems and letting me know what works and does not.

The WIX has always helped me when I need information for my various projects and always am amazes at the amount of experience that makes up the collective message board members.

Thanks,
David
VCS Aviation

[Ken]

Depending on how you see the airplane operating in the future or if there is a chance it will be sold, you may want to do some homework on the coming FAA ADS-B out (& in) requirements & capabilities for January 2020. I don't know if any specific exemptions will exist for vintage aircraft. No matter the route you choose, this is the ideal time to dedicate the wires, circuits, and proper grade antenna cable to prevent the headache of a re-do later. Just my 2 cents.

Ken

[Cvairwerks]

Look at running a Collins VHF20 transceiver and a Gables control head. It's a remote box that will take either analog or digital control heads.

[Speeddemon651]

Just to play devils advocate.....

Original radio's in a T-6G model per 1952 weighs roughly 79 lbs total. Authentic radio's are great but with modern radios you set them and forget them till your need to swap a frequency, save a lot of weight, you can focus more on your gauges and scanning the sky for other aircraft.

[Chris Brame]

Hi David! What's new on the P-35A project? (Sorry as usual for the thread hijack)

[Taigh Ramey]

Hello David,

I have flown with handhelds in an all original aircraft (Beech RC-45J, AT-11, SNJ and the PV-2) that had no good spot for a fixed install and if set up properly they can be very good and reliable. External antenna is the key to a good working handheld. I have also run a handheld through an original WWII AN104 VHF antenna with excellent results. Do not believe what some people say about the WWII antennas as they are better than a lot of what is being manufactured today.

BT-13's did have AN104's installed with the SCR-522 transceiver as can be seen in many period photos but it would have been a late war thing or as a field mod. If you are going to use an AN-104 make sure it is installed correctly and that the metal cover over the wood is far enough away from the structure. At least 3/8 of an inch. There are also grounding concerns too so call or email me for more info.

I am under the impression that most BT's had the SCR-183/283 as the command radio. The 183/283 transmitted on medium and high frequencies and used a long wire antenna that fed from the radios to the mast and then the tail. There is a feed through insulator for the long wire on the right side of the forward cockpit near where the radios are on the shelf. If you do not want to use the WWII radios then you can put an extra insulator in the antenna wire about 20 inches up (calculate the quarter wave length for VHF 118-136) from the feed through insulator. This will work as a good VHF antenna but there could be blanking issues being next to the fuselage like that.

If the wire or AN-104 ax handle antenna is not a good option for you then use a wire whip VHF antenna as it is unobtrusive and can be placed in hard to see locations. These are available at all avionics shops.



For more radio options besides the hand held please consider the nice and small Becker or the newer TRIG VHF comm and transponders. These are great and also have remote head options. The new TRIG is a lot cheaper for the remote version when compared to the Becker. Nice and small remote heads for VHF and transponder so you can mount the main unit elsewhere.

Here is the TRIG head which can mount in a standard 2 1/4 inch round instrument hole or something close



The transponder head



You can hide these two or mount them on a removable panel on the right side or wherever. More money for these cool units but you can't beat the quality. Use an ipad or iphone 6+ and Foreflight and a paper chart for your nav and you are good to go VFR.

More options at spruce

http://www.aircraftspruce.com/search/se ... er&x=0&y=0

http://www.aircraftspruce.com/search/se ... ig&x=0&y=0

As for the intercom I would recommend the PS engineering high noise intercom which works great. You can fix a phone and mic jack in a hidden place or run it through the original jack box.

I am all for keeping it original and authentic and I applaud your efforts to do the same. Keep the old radios and make them work too its a kick and fun to demo too. You can even get an amateur radio license and run them legally. Keep the wiring stock and add a modern harness for the avionics that can be removed later if desired. Try not to drill an extra hole if you can get away with it but make it safe and legal. A little forethought and extra effort really pays off in this area.

Sppeddemon651, please don't take offense at this but the arguments for getting rid of the old radios is hard for me to let go without comment.

I am not saying to try to use them as legal radios for aircraft comms because it is not advisable or legal. You can get them working for fun and it adds another level of authenticity and coolness let alone value. Just having them in even if they don't work is not for everyone but it is a great tribute to those that designed, built, maintained and used them. Radios and those that made them certainly played a big part and still do.

The weight issue is one that irks me. If you carried an additional 80 pounds in your T-6G would you really notice the difference when flying it? Would it have really made a difference in your aircraft performance?

The weight debate has been going on forever. We aren't talking about very much at all in the grand scheme of gross weight. Even with the larger bombers that carry a hundred pounds of radios or more. Would any pilot of a B-25 today really notice any difference if his Mitchell weighed an additional 100 pounds? Now a combat ready B-25 with all of the armor plate and bells and whistles and working turrets will be a heavy bird as do the totally authentic fighters but those are few and far between and can open up a discussion of their own. How about a fuselage fuel tank in a P-51D full of fuel? Now that's a different discussion all together.

The SCR-283 set in the BT-13 might weigh 35 pounds sopping wet. Once again I challenge you to feel a 35 pound difference in an aircraft with a gross weight of 4500 pounds. That's what, under one percent of gross?

Ill get off my save the radios soap box for now

[Speeddemon651]

None taken, I just wanted to give a different perspective. It's really all in what you want to do with a warbird.

[flightsimer]

Well, I had a long message typed up and posted it, but for some reason it did not post... so I will post a shortened version.

But if there is any desire for an on board GPS by the owner, another option would be to install a Garmin GTN 635 GPS/Comm or GTN 650 GPS/Nav/Comm, depending on if there is a VOR receiver or not. And then I would suggest also installing the Garmin GTX 33 remotely mounted Mode S transponder that will interface through the GPS screen. The entire setup is about $14,500 for the equipment plus installation costs if you can not do it. However, the GPS and Mode S option will have you ready for NextGen as well as it will give you the ability to see other Mode S aircraft on the GPS display.

If there is no desire for on board GPS, then what Taigh suggested would be adequate. The GPS should be able to be mounted either along the sidewall or under the panel in between the legs, either of those locations would be out of sight from anyone outside of the plane and even any passenger.

Even with my heavy use of foreflight (I have three devices I fly with, one primary and two backups) and a bad elf ipad GPS, I still like having an on board GPS to cross reference.

[VCS1]

Wanted to thank everybody for their responses (especially Taigh).

Allot of good ideas, anybody have any pictures of some installations?

[flightsimer]

Here is a picture of the Becker setup in between the legs in a yak 50.

The GTN635 could go in the same spot.

[tow-3]

take an old radio and mount a modern unit inside the box and build a removable face plate from the old radio plate

[mlenoch]

AN104 antennas do work. The ground must be carefully constructed to enable it to work. I simply wrapped tin foil [left over from my hat ] around the base of the antenna and provided a solid connection/contact of the foil to the airframe. Crude but simple.
My KX165 used the AN104 antenna. Never an issue with air-to-air formation or ATC communication.
FYI,
VL