It Flys
 

Took the Diesel to the field today, got two flights on it but was having some engine problems so decided to take it home for a good check over. I will swap in my 160 which is running well at this time. Plane felt good, tracks real well and rolls nice but is carries quite a bit of up trim. Here are a few shots at the field. To tired to go into detail but so far I like it. A hair over 10 lbs. dry!

RE: It Flys
 

Great to hear Brian. This means its really close to all the other Oxai models we have flown. It should be about 1/16" of up trim.

The question is how are the up and down lines. Its pulling I bet a touch in both. Slowly shift your CG aft just a little until the upline is dead on. When this happens you will be at the best CG point. Now look at downlines and it will likely pull very slight. A small throttle to down elevator will take care of this. If you want it to be a little more aft CG then you can shift it back a bit more and the pull on the downline will go away also. I feel the models track better more forward CG than Aft. So I compromise with the mix in the downline. You should be about zero for knife edge mixing and CG really doesn't play a role in this model unless its really far out of whack. I flew one really tail heavy and it started pitching belly but that was when it was hands off inverted. Not very easy to fly a model this way. Some will choose this setup but I think its tough on the pilot. The suggested CG is like 175mm aft of the LE at the fuse side for the one piece wing model. My Pinnacles are at 180mm and 182mm aft of the LE at the fuse side. This was eliminate the slight pull on the uplines...Both have near no mix for elevator and zero for aileron with rudder input. In my two models one model has a 2% up mix with like left rudder and nothing on right and the other model is zero elevator on both sides. This is knife edge looping rudder input gets the 2% mix.

Next thing is as you shift the CG back the up trim needed will be reduced. Once its dead nuts straight up and slight pull down, then dial the stab a little negative and fly it. You will be taking some of that up trim out...But get the upline right first....

It might take a full turn on the adjuster. Remember this adjuster is on the bottom of the rear tube. SOOOO clockwise on the screw will lower the rear tube or give positive in the stab and CCW will raise the rear tube and reduce the incidence on the tail.

All of the Oxai models I have seen fly or flown myself have been in the same state. This is all the trim that I have found needed. One had a little wing tip weight added....but the others this is about it for adjustment. I usually dial the wings a little more positive on the Pinnacle as this reduces the up trim also and raises the tail in flight. On the one piece wing model you don't have this option but dialing the stab will do the same thing. All the angles are relative...So negative in the stab is the same as positive in the wing.

Obviously you got the differential close from our conversation on the phone. I hope the throws were not too far off. As I said my setup is a little hotter than what you might need for Intermediate but its a baseline. I know my throws will yield good snaps, and spins without switching flight modes.

Let me know if there is anymore I can do to help. These things really fly well.


Troy Newman

RE: It Flys
 

Thanks Troy, I should get a good bit of flights on it next week. Elevator trim was more like 3/32 of an inch of up. I hate to say to much as I really did not get to fly it as much as I would have liked. I do remember trying some flat turns and it was pitching to the belly and in knife edge flight. Inverted flight needed a good push I but did not remember it being excessive. I started with the CG at about 180mm but I don't get to technical with CG setting on the bench as I get it in the ball park and fly it, could have been 175mm? I will deffinitly start moving it back. Only other ting I noticed was some Ail. trim, Ailirons have about a 32nd to a 16th of an inch warp from end to end so setting nuetral was difficult, Im going to try and straighten them this week by clamping one end to the bench and shimming the other end a little to see how they will react. Next week I should be able to get a couple gallons through it and sort these things out.

RE: It Flys
 

Brian,
Glad to see you got your new weapon of choice flying. Better get some crosswind practice, as I'm paying the weatherman extra for wind at Andersonville! And I just completed my 6th contest of the year at Baton Rouge, so I'm gunning for you!!

Jon

RE: It Flys
 

Dam, don't you work? lol. I'm trying but time has been limited this year. With all the contest under your belt allready you should have no problem. We got four flyers from our field going to Andersonville, two sportsman, Billy and me. After Andersonville the only other two contest I can make for sure is Jacksonville in Sept. and the championship in Gay GA. I don't have any out of dist. close enough to attend and looking at the schedule the others don't seem likely. Thats only six contest for the season for me which should make the dist. Championship yours with no problem. I will try my best to whip you at whatever contest we are at, lol. The schedule is kinda rough for me as there are three contest just in June all up north, Andersonville 6-3-06, Harvest, Al. 6-10-06, Cullman 6-24-06, then in August there is Knoxville 8-5-06 and Nashville 8-26-06{ trying to make one of these if I can but looks unlikely at the moment } then it's back up to Huntsville in Sept. Happy flying, see you in Andersonville.

RE: It Flys
 

Hello,
if I can, one question Troy...

Here you suggest to move CG aft to correct pulling during uplines, but why don't we add more down-thrust to keep the forward CG?


Thanks in advance.

RE: It Flys
 

You could and I have done this. The thrustline change has other effects like it creates even more up elevator trim for flying level. So now the model pulls to the canopy even more on a downline.

The best results I have found is the Pinancle flies better with the CG adjusted to correct the pull on the upline. When this is done model is still balanced very forward from where most pilots fly their models today. I just think the stock CG of 175mm is a touch forward and the model carries a little up trim off the boards. All the Oxai's I have flown have had this. Slide the CG back to about 180mm and it all goes away and the models still track excellent. There is a needs for a very slight down elevator mix on the downline and its done. As you give more down thrust to the model you are causing a force that must be overcome in the tail. When the force at the nose is removed now the tail is still acting. Moving the CG 1/4" or 5mm does the same as the downthrust for the uplines and also reduces the pull the canopy on the downlines. I have rarely seen models that don't have a slight slight pull to the canopy in a power off dive. I have been able to mitigate it or reduce it signifigantly but I don't think I have been able to trim the model to track properly based on CG and still have the CG aft enough to remove the pull to the canopy on a downline.

all changes you make in trim are a compromise. The Deisel and the Pinnacle are very similar and in fact the wings are almost the same. The fuse shape is a little different but the moments and important stuff are so much alike.

If I had a deisel I would try sliding the CG back to remove pitch tot he canopy in the upline and help reduce up elevator trim. I think the Pinnacle has some improvements like less pitch coupling but the Deisel can be mixed out and if you do the mix properly it won't affect the other attributes. Mixing is not something to afraid of its just another tool to make the model do what you want it to do. Again its a compromise. The big 40% models tend to have large amounts of mixing like on the order of 10-20% sometimes and they still fly very well.

Troy Newman

RE: It Flys
 

Ok Troy!!!

Many thanks for the complete explaination and your willingness!!!