Bill Do you remember how or if removing the nacelles and engine weight forward of the spar affected the wing system for flutter. It seems like the engines or fuel in the tip tanks would act like a forward balance weight and prevent twist of the wing as AOA increased during a pull. Or is the wing center section stiffer than needed so the weight being removed not matter.

Different skin thicknesses on a 421 or 414 with tip tanks vs no tip tanks later?

Don't remember anything about it.

Bill, you should write a book, or memoirs of what you remember. My first full time flying job was in a 402C (and B and 404), managed a 421C and 441 and 30 years later own a 414. I've flown most of the 300/400 series fleet other than the 336/337 and 425. Information like this thread intrigues me!

I've got the books by William Thompson and I couldn't put them down when I got them for Christmas!

Not up to writing a book, but here is what I worked on:
Prototype to Production:
441
425
F406
750
Protoype Cancelled
435
Experimental Only
ATPTB (Turboprop pusher 550)
Coax
250 (Allison engine P210)
Military Proposals (lost them all)
NGT
OSA
TTTS
Other Production/Field Support
300's, 400's, 208, Most Citations
Flew as PIC
Most tri-gear singles (Employees Flying Club)
T303 (Service Test)
P210R (Service Test)
414A (Company Transport)
Flew as an observer/test witness
Most I worked on

That's quite an interesting career Bill.

There is a Facebook page for Conquest. About a year ago, one of your coworkers put a handful of short stories on the page. Gary White is his name.

Bill do you remember why Cessna did not go further with the ATPTB concept.

Seems like a much more efficient airframe for a Turboprop and it could have been a good
Cessna 441 replacement.

I wonder the power off full flaps and clean stall speed of something like a Phenom 100 is the same as the Kingair 90 but with 100 sq ft less wing and similar weights.

How do they manage that? Just the removal of nacelles or is it the disturbed airflow over the wing power off from the props.

I lost my Facebook account (long story), but I remember working with Gary White.

Why we didn't go further was sort of above my pay grade. One possible reason was return on investment. Another was possible competition with existing Citations (why spend a lot of money to compete with yourself?). The testbed involved quite a bit of hand-waving and short cuts, which would have required more drawings, tooling etc. for a real production prototype. I think there were some W&B issues also where ballast would be less acceptable for a production version.

Don't really have an answer to your stall speed question, sort of beyond my area of expertise.

Bill,
Would you be able to tell us a bit about that project?

Why Cessna didn't continue that development?
And did Myron at O&N pick up the pieces after Cessna for his Silver Eagles, or did he start from scratch?

It was another testbed project. Don't know why we didn't continue (above my pay grade), but the following may have been factors:

May have been too expensive for the market, mainly due to engine cost.
Other/better uses for development capital.
When using max climb and descent performance, it was an ear popper. Really needed more pressure differential, which would be a big deal.
Zippy down low, but no faster then a P210R up high
Some certification issues, such as turbine airplanes not allowed to manually switch tanks, required turbine engine ice protection, and likely required compliance with most recent regulations/advisory material/interpretations.

AFAIK, there was no relationship between our project and the Silver
Eagle.

Bill,
Would you be able to tell us a bit about that project?

Why Cessna didn't continue that development?
And did Myron at O&N pick up the pieces after Cessna for his Silver Eagles, or did he start from scratch?[/quote]

It was another testbed project. Don't know why we didn't continue (above my pay grade), but the following may have been factors:

May have been too expensive for the market, mainly due to engine cost.
Other/better uses for development capital.
When using max climb and descent performance, it was an ear popper. Really needed more pressure differential, which would be a big deal.
Zippy down low, but no faster then a P210R up high
Some certification issues, such as turbine airplanes not allowed to manually switch tanks, required turbine engine ice protection, and likely required compliance with most recent regulations/advisory material/interpretations.

AFAIK, there was no relationship between our project and the Silver
Eagle.[/quote]

Edit to add that the engine is the big cost driver but there are others that add up, such as starter-generators, beta/reversing propellers, redundant fuel pumps, bleed valves, etc.