Hughes TH-55 Osage

[Whirlybird]

53 minutes ago, BWDenver said:

Just got some rather interesting information.  In the 1971-1972 time frame the pilots in the TH-55A encountered Carbon Monoxide issues due to rust through on the muffler, which may be why they were lacking from the birds I flew in early '73.

That is interesting...still trying to understand how the whole exhaust system and heating blower attachment system operate and are set up.

[BWDenver]

A heat exchanger chamber is placed over the exhaust stacks.  Air inside the chamber is heated by the exhaust pipes with the exhaust eventually exiting out of an outlets.

 

The downside of this method is if there is a leak in the system, Carbon Monoxide will be introduced into the cockpit.  This is a significant safety issue with reciprocating engines.  Turbans use bleed air that diverts air from the compressor section. The advantage is the air is heated by comprehension, not the exhaust system.  the down side of Bleed air is it reduces power and can impact range.

 

The blower mounted on the RH side of the cabin forced air into the orange air channels into the aft end of the Heat Exchanger, when the valve is opened heated air is ducted up into the cabin.  When installed the blower is always on, and controlled via a mechanical knob that you pull to increase heat flow.  The flow is controlled by the pilot as he pulls more on the control to increase air flow.

 

Should clarify, as he pilot pulls the knob the flap on the valve is closed to allow hot air into the cabin.  As seen below the air knob is pushed all the way in, and closing the path to the cockpit...

 

The mufflers were removed when the heat exchanger is installed.  It looks like they were both removed when I flew them,

 

You can see the air vale in the image above.

Edited September 15, 2025 by BWDenver

[Rob Mignard]

Here’s the earlier setup. It had the same problem with carbon monoxide if a leak developed. These photos were posted earlier, but the one of the left side was reversed.

[Winnie]

The orange hose are SKEET or SKAT hose depending on single wall or double wall... 

 

flew 1900 hours on the 300C, CB and CBi, and the system is similar to the first picture!

 

We had a plastic disk to warn about CO poisioning, it'd change color...

[JohnEB]

3 hours ago, Winnie said:

 

wWe had a plastic disk to warn about CO poisioning, it'd change color...

Those are almost stand nowadays in general aviation aircraft.  It's too easy for a system to leak, A very inexpensive precaution.

[Whirlybird]

While I'm waiting on the dimensions for theTH-55, I'm looking at other builds.

 

I've been thinking of an instrument trainer version of the OH-13 (TH-13T).

Aside for the color scheme (orange), I think the changes were more inside the cockpit.

 

I know they put a black curtain wall across the right-hand floor to block the view outside while relying on instruments.

Anything else different?

 

 

 

Edited September 19, 2025 by Whirlybird

[Rob Mignard]

Here's a few baseline photos and drawings of the TH-13T.  The drawing is a weight and balance chart, so it's not completely accurate. The bubble and doors are tinted blue. The overall color is trainer organe. The T model (which we called the torture model) was easy to fly and a very good instrument trainer. I can supply as much detail as you can stand on this helicopter also.

 

Mig

 

 

[BWDenver]

Great shots Rob,

 

Here are the shots with a little bit of editing.  I normally shoot birds and do a lot of editing. 

Any idea what the missing instrument in at the bottom of the panel?

 

 

Left rear

 

Right rear with a few dark areas.

 

Kinda make me want to do one...

 

 

Or you can go way over the top and build Bell's 1st Turbine helicopter, the OH-13F first flight circa 1954.  Image via Ray Wilhite and the Ft Rucker Test Board.

 

 

[Whirlybird]

"Any idea what the missing instrument in at the bottom of the panel?'

 

It's for the fault indicator for the Fail-Safe box.  : )

Edited September 20, 2025 by Whirlybird

[BWDenver]

2 hours ago, Whirlybird said:

"Any idea what the missing instrument in at the bottom of the panel?'

 

It's for the fault indicator for the Fail-Safe box.  : )

OK Ray, that make it clear......  😜

[Rob Mignard]

On 9/18/2025 at 6:06 PM, Whirlybird said:

I know they put a black curtain wall across the right-hand floor to block the view outside while relying on instruments.

Anything else different?

 

How much information do you want? There are a great number of differences. Are you looking for a show-stopper, a 3 foot model, or something in between. I'll be happy to provide as much information as you need.

 

Mig

[Whirlybird]

12 hours ago, Rob Mignard said:

How much information do you want? There are a great number of differences. Are you looking for a show-stopper, a 3 foot model, or something in between. I'll be happy to provide as much information as you need.

 

Mig

 

I have an Italeri OH-13 kit (1/48th) that I thought would look good in "trainer" orange.

Where the kit is lacking, I'll add some more details.

 

Think it needs a separate build thread, which I can start. 

 

 

 

 

 

 

[Rob Mignard]

It would be significantly easier to build an OH-13E. They were used as primary trainers at Fort Wolters along with OH-23's and TH-55's. They're orange and OD, but still interesting. There's a thread on britmodeller (https://www.britmodeller.com/forums/index.php?/topic/235119012-bell-th-13t-instrument-training-helicopter-ft-rucker-alabama-1970/) that shows an attempt at a TH-13T that may (or may not) inspire you.

 

Here's a few photos of  Fort Wolters OH-13E's.

 

Let me know which way you want to go and I'll support whatever you need.

 

Mig

 

 

 

 

[Whirlybird]

Started a separate thread for this project.

TH-13T- OH-13E Instrument trainer - Helicopter Modeling - ARC Discussion Forums

[Whirlybird]

I was getting ready to visit the museum at Ft. Eustis to meet the curator and make the measurements on the Th-55.

 

Before I left, I called the curator at the museum several times and no one answered.

 

I finally got ahold of information, and they informed me the museum is closed until further notice, due to the Government shutdown.

 

No idea when it will reopen.

Glad I called ahead.

[BWDenver]

Bummer!

 

Good you called ahead!

 

Bryan

[Whirlybird]

Well, it gave me time to finish some other stuff.

 

Roswell '57 - Sci-Fi Modeling - ARC Discussion Forums

[rvrman]

I received this model as a gift Christmas 2024.  I’m getting ready to start building now as I’ve been fully retired for about a year.  I am going to build this model as a civilian Hughes 269a, and want to match the turquoise paint color as those aircraft came from the factory in the 1960s. Can anyone help with the actual color needed?  I’m having trouble finding any Testors or other model paints that are an exact match.  Any suggestions are helpful!

 

I scratch-built a Hughes 269a about 5 years ago that I was pretty proud of; I gave it to my nieces husband when they married since he was an instructor in these helicopters.  I have found all of the comments about modifications to this AMP model to be most helpful!  Hoping someone can help me with the factory paint color.

[Loach Driver]

I have some old Hughes promo booklets on the 269/300. I will have a look but I don't recall any mention of that turquoise blue in any of them. Is this the shade of blue you are referring to?

 

https://www.swissheli.com/history/hb-xcz.htm#

 

https://abpic.co.uk/pictures/view/1730522

 

https://447bg.org/helicopters/th55-osage/#gallery/0b70d2e50a16bb26529505e7918b438f/12806

 

LD.

 

 

[rvrman]

Yes, Loach Driver, the first two pics are exactly what I’m looking for!  Any help you or others could give me in either locating that color or a place I could have a custom color mixed would be great!  I’m just trying to re-create the model as I remember from my childhood.

[rvrman]

And while we’re here, what company do y’all typically use for civilian decals — N-numbers and such?

[Loach Driver]

1 hour ago, rvrman said:

And while we’re here, what company do y’all typically use for civilian decals — N-numbers and such?

 

I've heard this guy does a good job. I haven't sent him an order yet but will be trying him when I need some decals in a month or two.

 

https://www.lmdecals.gr/index.php/en/

 

LD.