UH-1B upgrades question

Mon, 2010-02-08 22:35 — mdyank

For starters, my apologies for what is probably a very dumb question from someone who is far from expert in the field of helicopter gunships.  I also am willing to bet that this topic has been covered before though I've had trouble locating a discussion.

In looking at photos of some UH-1 gunship airframes, I am noticing that although the vast majority of the early models are UH-1Bs, particularly during the 1960s in the case of HA(L)-3, a number of airframes with UH-1B serials appear to have been modified with UH-1C attibutes.  I've seen references to the effect that some UH-1Bs were upgraded with the UH-1C rotor assembly, and there appear to be many examples of UH-1Bs with the later-style air filters, but while it is difficult to evaluate the rotors in the photos I am seeing, they definitely show the larger tail assembly in addition to the larger air filter assembly. 

If these UH-1Bs got new tails, did they also get the UH-1C's upgraded engine?  Or did the larger tail have more to do with the new rotor assembly than the power of the engine?  Most photos don't seem to show the horizontal stabilizers very well, but if they got upgraded engines, rotors, and/or tails I wonder if those were changed as well. 

Does anyone know the specifics of what was done to these apparently modified UH-1Bs, and how widespread the modifications were?  Did they truly, in effect, convert B models into C models, or did the changes stop short of that?  It makes me second-guess how many of the "UH-1Cs" I've seen in photos were really C models...

Thanks!

‹ Westland Lynx, scale drawings, any about? Helicopter pictures from Flesland outside Bergen on the westcost of Norway. ›

Comments

Tue, 2010-02-09 08:30 — rotorwash
rotorwash's picture

UH-1B mods

Oh man, where to start.  You're right, this topic has been covered quite a few times on a number of forums.  I know I have typed pages and pages on it.  In a nutshell, there were probably 2 or 3 UH-1B airframes that carried the 540 rotor system of the UH-1C during it's early development.  NONE ever made it to Vietnam that I can find. The 174th AHC has been noted as having "540B's" however, US Army Gold book data shows that the unit only had 1 UH-1B and it only served for 10 hours!   What has been called 540B's are, in fact, UH-1C's with the old Bell mouth intake.  Otherwise, they have all the UH-1C features.  UH-1B's and C's can be distinguished by several key differences.  The B has a 204 rotor with a 21 inch chord, the C has a 540 rotor with a 27 inch chord.  The B has a right handed fuel filler, the C has a left handed fuel filler.  There are about half a dozen weird B's I have seen with left handed fillers and most belonged to the RAN.  The UH-1B has a nose mounted pitot, the C has a roof mounted pitot.  The UH-1B has narrow horizontal stabs (21 inches) with a symmetrical cross section.  The UH-1C has wide stabs (27 inches) with a asymmetrical cross section.

Now for the stuff that DOES NOT separate B's and C's well. First off, the particle separator. That mod is TIME specific not model specific.  The first UH-1C's all had the old bell mouth intake, the particle separator was introduced about mid 1966. In fact, I have test board pics of it being tested in July of 66.  Therefore, both B's and C's after late 66 or 67 could have had the filters installed.  The tails are also not conclusive.  The old UH-1B narrow tail was never carried by C's so it is a good ID tool.  However, numerous UH-1B's recieved UH-1C tailbooms with the wide chord cambered tails due to structural weaknesses or failure of the old B boom.  However, they still retained the narrow UH-1B horizontal stabs.

UH-1B's entered service with the Lycoming T53-L9 engine.  I'm not sure if any got the L-11 engine or not.  All UH-1C's had the L-11 engine and late in the war some were upgraded to the L-13 (same engine as the UH-1H). However, they were designated UH-1M's at that point.  You will see refs that say that the UH-1M was a UH-1C that was fitted with the INFANT (Iraquois Night Fighter and Night Tracker) system. In fact, the INFANT birds were all UH-1M's but just due to the upgraded engine.

OK, that's enough for now.  I have photos of all of this stuff, but it's too late for me to get all that together right now.  I hope this short intro helps a little though.  LONG LIVE THE HUEY!!!!

Ray

Ray

Wed, 2010-02-10 17:29 — mdyank
mdyank's picture

Thanks Ray, that's extremely

Thanks Ray, that's extremely helpful!  I'm sure that the photos I was curious about show Bs with new tails, which makes a lot more sense now.  I'm not sure I can resist building one now.  Very much appreciated. 

-Will

Thu, 2010-02-11 05:08 — rotorwash
rotorwash's picture

Your welcome

Will,

Glad to be of service and please post pics of your build.  If you are building in 1/72, just get the Italeri UH-1C and UH-1B kits and use the tail and engine cowling from the C kit for a late war B with the particle separator installed.  You'll be good to go.

Ray

Ray