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OH-58A/206 Differences

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OH-58A/206 Differences

Old 9th Feb 2012, 04:40
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OH-58A/206 Differences

Anyone have any idea why Bell produced these two models with different rotor diameters and different gear box reduction ratios?

The gear box ratio can be answered I guess by the difference in rotor diameter, but who/what/why dictated the difference?
Brian Abraham is offline  
Old 9th Feb 2012, 08:27
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... military requirements ...
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Old 9th Feb 2012, 14:36
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Mmmm ...

Brian .... vaguely remember discussing this very question (soooooo many) years ago with a mate who was Ex 161 Recce.

Apparently when ordered the CA32 (B206B1 Kiowa) the powers that be decided the beastie should come with the 'LongRanger' M/R blades and this then required the longer LongRanger T'boom as well and the slightly upgraded engine, Tailrotor and T/R G'box.

I believe the T/R g'box and longer T/R blades required the ratio change in the Xmsn (was prob also a LongRanger M/Xmsn .. I don't really know?)

At the time of said discussion we were also comparing the merits of various alcoholic beverages so accuracy of memory storage unit is doubtful ?? I would be happy to be corrected on the above blurry data???








BTW kindly say 'Hi' ... to Ross M if you happen to see him ... Cheers
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Old 9th Feb 2012, 18:22
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OH-58 had requirments to the military spec, the Bell 206 had CAR 3.
The airframe on the OH has the battery in behind the fuel tank (No nose door) fuselage has different stations & construction .Doors jetison,Armor backed seats,Hard points for guns, T-63-700 allison power (C-18) needed larger blades for disk loading requirments, So many little things are not the same, Mission equipment all over-Flew both-Worked on both.

Both are nice machines.
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Old 14th Feb 2012, 08:29
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I've been waiting and hoping that this thread would develope more than it has before it began to drift. So here goes, it reminds me of the time in the early 1980's when an Asian air force bought a couple of Bell 205A-1's to supplement their UH-1H's thinking, or having been told, that "they're the same". Of course they're not and anyone who knows both models will tell you that the only thing that is similar is the silhouette. The structure and the systems are all significantly different, even the engines are different (look it up).

Undeterred, the air force contacted Bell asking how to convert a 205A-1 into a UH-1H, or as a minimum, how to convert the 205A-1 instrument panel to match that of the UH-1H. The reply from Bell became something of a classic at the time, it said that there were so many differences that it simply was not possible to achieve and added "even the rivets are different"* and ended with "we suggest you sell the 205A-1's and use the funds to purchase UH-1H's".

* UH-1H magnesium structure vs. 205A-1 aluminium structure.
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Old 15th Feb 2012, 00:52
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UH-1H magnesium structure vs. 205A-1 aluminium structure
Not entirely true. About the only difference was the 90 gearbox support casting was magnesium and the horizontal stab. Some companies have engineering programs in place to replace the magnesium components in military models.
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