| Author | Message | ||
     jvillalva |
I'm changing my elevator cable control system to the new factory push-pull tube system (along with the new flap system). I've seen photos that show the forward elevator bellcrank re-drilled in a new location. In the Express-Builder Gallery site pictures, under the Factory Pictures in the Fuselage Interior section (photo 13 of 31), the forward elevator bellcrank is re-drilled closer to the torque tube. Is this a Series 90 change or is there more to story? There is a second picture in the Avionics & Control Panels section (picture 6 of 10) showing the same thing. What are the maximum up and down elevator limits for the CT tail? What is the total throw required at the aft elevator bellcrank? My figuring shows about 2-3/8" for 25 degrees up and down travel of the elevator. | ||
| Jerry Sjostrand (Jerry) |
Hi Jay; The limits that work very well for the CT are 30 degrees up and 15 degrees down. I suspect that 25 up would be OK. Rudder throw should not exceed 20 degrees center to side. Maybe someone else can help on the elevator push-pull tube set up. | ||
| Kevin Dennes (Kdennes) |
Jay. I know that you are building the CT (which I know little about) but just for the record, Larry suggests 25 deg. up and down for the 2000. Maybe this is totally different for the CT. Regards. Kevin (from Downunder) | ||
| Jerry Sjostrand (Jerry) |
Hi Kevin and "builders". A consideration which has passed around for some time. Can you imagine what the airplane would do if you used 25 degrees of down elevator? Inverted loops? We do need plenty of "up" for landing flare, practice stalls----Hmmmm!!! You will never need (nor want to use) more than 10-15 degrees down elevator. Why build in more? Any other thoughts out there? | ||
| Sven-Ake Eriksson (Sven) |
Hi folks When I purchased my CT kit from the former owner I got some documents with it that probably is specs from before first flight for any express. Dated back to feb 1987 these documents contains a lot of design data and among them the following. Ailerons up/down 19/12 degrees. Flaps take off/landing/cruise 0/+36/-10. Elevator travel up/down 16/12 degrees. Elevator trim travel +/- 10 degrees. Rudder travel right/left 20/18 degrees?? Wing dihedral 5 degrees. Wing angle of incidence +2 degrees. Horiz stab angle of incidence -0.5 degrees. Aircraft empty weight, document #1 1100 lbs, document #2 1350 lbs. Gross doc #1 2300 lbs, doc #2 2500 lbs. Fuel 50 Gal. Engine lateral offset 2.5 degrees starboard. And a lot more... Some of the documents are bad copies and can not be sent by fax if someone should want me to do so. Compare these values with what is used today! Rudder travel, for example, is found to be a maximum +/- 20 degrees by practical tests. Gross weight with original construction is upped to above 3300 lbs !!! Sven Eriksson | ||
| Jerry Sjostrand (Jerry) |
To add to Sven's notes. Looks like the original prototype data. (Horiz stab angle of incidence -0.5 degrees.) It was changed to .8 on second prototype. Wing dihedral is 5 degrees on the bottom and 4 degrees on the top (1 degree spar taper) You need all the elevator travel you can get. Cheers, Jerry | ||
| Jerry Sjostrand (Jerry) |
Correction: The (0.8) is (minus)-0.8 Sorry Jerry | ||
| Sven-Ake Eriksson (Sven) |
Sorry, I forgot to add the comment that the data above is the theoretical values for the express in the late design stage. Of course there will be lots of changes when it comes down to flight testing. Reason why I decided to deal with this matter is an interest to show(and share with others) what the express was intended to be from the beginning. Request: Can anybody out there with a flying CT try the following. Put the trim tab in neutral and seal with tape. Then fly it and tell me approximately what stick forces to expect. Reason is to eventually install a spring trim system a la glider. To be able to do so the stick forces have to be low. Sven Eriksson | ||
| LOUIE LACY (Llacy) |
Sven I can give you an approximate. Some "dummy" while working behind his panel left the elevator trim tab unhooked. The forces are managable although quite a lot heavier than with the tab. I have the CT tail and the heaviest force was of course during the approach.It would be a guess on my part as to the exact force required for the landing Lou llacy311@tds.net | ||
| Reinhard Metz |
To add to Jerry's input, my CT tail is limited to 20 degrees left and right for the rudder, and 25 degrees up and 15 down for the elevator. That works well - I've landed with easily 25k crosswinds without using up the rudder, and the elevator trim stays within +/- 25% of center for all cruise weights and balances. However, when very light, I routinely use up 70% or so of up-trim on landing to keep forces to zero. When at gross and most rearward cg the landing trim will be close to neutral, and the nose wheel light on touchdown, and takeoff trim about 25% down. Light to normal takeoff trim is neutral to just barely nose down. Bottom line - I completely agree with Jerry's numbers. Of course, our weights are probably similar. Reinhard Metz |