There are thousands of reasons a designer would want to sell his design to another company. I do own a modeling company, www.soaringspecialties.com
. I mainly sell Airtronics radios and specialty sailplane parts, like servo wire, hinge tape and control horns.
I used to manufacture the BAe Hawk and the One Fun Design sailplane. I purchased the rights to the BAe Hawk because I wanted a kit and the designer wasn't making them any longer. I designed the OFD because Charlie Richardson wasn't going to produce the Fun One any longer and we still used that plane catagory at the Midwest Slope Challenge (MWSC).
I had separate companies making the fiberglass parts,and I did the rest of the parts. Unfortunately, my health deteriorated to the point that I couldn't serve my customers properly, not being able to get the kits out in a reasonable amount of time.
Some people don't want a second business building airplane kits or flyers for other people. They most likely have a day job and they want to see their kids and spouse when they get home. Also, when you start kitting airplanes, it becomes a job and some of the enjoyment is gone. Let's face it, how many wings do you want to bag in a week?
From a designers standpoint, getting royalty payments on say 2000 kits and getting a lump sum payment may be much more desireable than spending your free evenings putting balsa parts in boxes.
Continuing this thought, if the designer doesn't have the knowledge to produce say a fiberglass fuse, that will need to be farmed out or he'll have to learn to do it himself. The same goes for cutting foam. If the plane needs die cut or laser cut parts, they too will have to be farmed out.
And then there are the customers. Most customers are very nice and very understanding if you don't have a product in stock. However, there are a few that if they don't get their parts or whatever in 2 days, they post it on RCG and RCSE that the MFG is trying to rip you off.
I did have that happen one time. I thought I was going to get a part out on Wed. and it took until Friday before I could ship. I went out of town Friday morning for a contest and didn't have email access until I returned on Sunday afternoon. I had no less than 5 emails stating I was trying to rip the guy off and if he didn't hear from me by Saturday, he was going to post it on RCSE. Needless to say, I didn't email him on Saturday because I was out of town. Since I've been around for years, many people stuck up for me and told the guy not to worry. I emailed him Sunday afternoon and explained I didn't get it shipped until Friday and that he'd probably get it on Tuesday. He got it on Monday. Do you think he went on RCSE and told everyone that he finally got his part and that there was a legit reason it took an additional 2 days to ship the item? You already know the answer.
Who wants to deal with people like that? It takes patience and some people don't want to put up with the hassle. They would rather sell their design to a full time manufacturer that can supply kits in a timely fashion.
Another reason is having to deal with outside suppliers. When I get low on Bird of Time 'glass fuses, I order 5 more. It usually takes the guy 2-4 weeks to get fill the order. This last time it's taken 3 months! No email responces, no phone responses and no fuses either! I tell the customers about the situation when they order that I expect them in x-weeks, expecting the MFG to supply them in the normal time frame. However, in this case, I keep having to tell the customer I really don't know when I can expect fuses in. As stated before, most customers are patient and understanding, and then there are those that honestly can't wait. They have a certain amount of building time available and they need the fuse right then.
So there you have it, one manufacturers comments.