Sure, when the Bb horn is played as a horn, it is actually transposed into F. The difference is the trumpet is 4.5 feet and the Bb horn is 9. I have a single Bb horn I was using to try and force myself to learn the horn fingering. Still messes me up though. I'm probably just going to go back to a single F horn since I mostly play alto horn now anyway.
Re: how to play horn in Bb 06:58 on Wednesday, June 1, 2016
For some notes the F and Bb fingerings are a fifth apart, but you will often find that the tuning isn't very good, or that the fingering doesn't work at all. I think you're better off transposing (even if you write in the letters!)
Re: how to play horn in Bb 10:19 on Friday, June 3, 2016
The F and Bb fingerings are always apart, just sometimes they are the same fingering.
Horn players can't stand to play the Bb as a Bb because it sounds off to them because they are ear trained to hear it transposed as an F horn. If someone isn't used to playing Horn and just wants to play a Bb horn as a Bb part, they can pretty easily do so. Instead of using the transposed into F fingerings they just play the Bb horn as a Bb horn.
Maybe a transposing chart will help people understand. The Bb horn is right with the other Bb instruments. http://www.apsva.us/cms/lib2/VA01000586/Centricity/Domain/1036/Transp_Chart.pdf
