Here is my rough translation of Chen Weiming’s Preface to the brief section on Changquan in his book. From what I can gather, what Chen documented in his book was not a “Yang family long fist form,” but something Chen sort of knitted together from something that Yang Chengfu taught him, but that was probably not a “form” in the sense we usually think of it. It may have been discrete scenarios or short sequences. In Chen’s book, this Preface is followed by a page listing movement names from the changquan taught by Yang Chengfu. Next comes a page of expanded movement names for changquan, presumably compiled by Chen. Then there are several pages of explanations for each posture/sequence, very brief and sketchy.
Taiji changquan preface by Chen Weiming
Mr. [Yang] Chengfu taught me taijiquan, then he further taught me taiji changquan [long boxing]. Within [changquan] there are a number of postures that are not present in taijiquan; the remaining [postures] are fairly similar—only the transitions throughout are different. This would indicate, therefore, that taijiquan originally had no fixed methods, nor did it have fixed forms. Taijiquan and changquan both contain peng, lu, ji, an, cai, lie, and zhou; [it] only lacks one: kaojin. I wanted to add the kao of dalu to the quan [form], but after several years of hard thinking, I was unable to get a way of linking [the postures] together. Now, inadvertently, I’ve suddenly gotten it, so that the linkages make for a perfect seemless whole; I daresay I am pleased with it. Then I took those cases where taijiquan has a left form but lacks a right, or has a right form but lacks a left, and I’ve added them in for balance. I’ve also observed what is known as the old style of taiji as transmitted by the Chen clan of Henan. This “Step back dispatch monkey,” is like a retreating form of “Brush knee twist step left and right,” and the turning of the body is especially light and lively. So I’ve also added it in, naming it “Retreat step brush knee.” All together there are 108 postures. Having taken Mr. [Yang] Chengfu’s transmitted changquan and expanded it, I do not dare speak of having invented something, but with regard to the intent of taijiquan, there is some increase, but there is no decrease; there are some changes, but there is no copying. Perhaps this can be of some help for students in their researches.
—Weiming, Winter, 1927
So, my sense of it is that this provides no clear evidence that there was a “changquan” form in the Yang family curriculum. I also see nothing in Chen Weiming’s materials that suggest the changquan was faster, slower, more or less martial, or more or less important than the received Yang taijiquan form.
If anyone knows something more or different about the changquan materials in Chen Weiming’s book, I would be interested in learning more about it.