midwest Aerostar, 53" wingspan, .36 TT Pro engine, 4 channels, Spectrum DX6i TX.
I started this plane 20 years ago. I'm finally going to finish it.
I lost the instructions years ago.

Without the instructions I'm not sure of two things...

1. How far back from the lead edge of the wing is the CG and how much room for error?
I know tail heavy is bad!

2. How much movement do I need on the controls?
the info I have so far is
Elevator = 1/4" inch up and down.
Rudder = 1/4" right and left.
Ailerons = 1/2" up 1/4" down

(doesnt seem like much movement to me?)

What about the front wheel? how much movement here?
I'm having a little trouble with binding on the front wheel control line.
On grass, is the turning done with the rudder or the wheel or both?

Getting close, should finish up this week? 1st flight next weekend???

Thanks for everyones help

Pop

I do not have that particular plane and if it happens that you could not find the right info, I would suggest you to go 1/2" right and left on rudder and as per the cg try to locate it close to the main spar of the wing (Thickest part of the ribs), and you should be safe there. Try some test flights and then rearrange the control surfaces and CG until you feel it comfortable.

If you have a yardstick and the model, there is a 100% reliable way to find where the CG range is for that model.

http://www.geistware.com/rcmodeling/cg_super_calc.htm

9 measurements and that's it. Plug them into the application. Put a value of 5 for the Desired Static Margin and click the bar. Readout the CG location down where it says: Ideal CG aft of root LE =

Then do the Static Margin for 15%. You're now good to go for your CG range.

Very often the rudder servo is rigged to work the rudder with a pushrod that goes aft and to work the nosewheel with a pushrod that goes forward. You often use a servo wheel or star to attach the two pushrods. It's kewl because you can adjust your rudder throw by moving it's pushrod connection in or out, and adjust the nosewheel the same way. If you look closely at the servo on the left in the picture, you see the rudder connection is as far out as it can go. The nosewheel pushrod is connected to a hole closer in on it's arm. The nosewheel turns less. It's easier to steer that way.

Do all the suggested work and come up with whatever or do it easy and be right. Your wing is a typical retangle so just balance the finished machine 25% OF THE CHORD back from the LE of the wing. If you have a straight tapered wing, you can find the average chord and go back there 25% of the average. Will be within a 1/4" which is close enough for a toy airplane trainer.
Now after all the bugs are worked out you may want to move the CG back a bit to, say, as much as 30% MAC.

Depends on your flying skills. I would like 1/2" on the rudder with 1/4-3/8 on the nosewheel. Doesn't take much. Less on hard surface.
Good aileron advice for good differential.

Until the machine begins moving, nw is most effective. Once some airspeed is attained and with the prop-wash over the rudder, it will be effective. Good luck.

BTW, the manufacturer's suggested CG location is just a starting point. Matter of fact, every "rule of thumb" or formula works out a starting point, nothing more.

A model with a wing chord around 12" will have a CG range of about an inch, depending on how large and far aft the tail is. An inch is a lot of range. And anywhere in that inch will be ok if you setup the elevator throw as suggested.

The CG location and elevator throws work together. If you decide on a forward CG, make sure to have at least the full elevator throw that was suggested. If you setup the CG aft of the range, then expect the elevator to be very effective and rig the elevator conservatively.

DA ROCK I was looking at your picture and I noticed that the push rod connectors are the great plane metal heavy duty ones. I rescently purchased a pack of these and noticed that about half of them the pin is falling out as in it is loose and the other half is tightly affixed in place. Is this a common thing or do I have a bad batch?

Never encountered any that were loose and none that fell out. These are the 2-56 size. I've used them for years because they are the most robust and uniform. I also have a pack of the 4-40 size so know they sell larger ones but haven't ever used them. I stick with 40-60 size models.

Most airplane designers put the spar at or close to the recommended CG. This helps to ensure the lifting forces are acting at the strongest part of the wing. The center of lift is also typically at the thickest part of the airfoil, which again, is normallywhere the spar is located, as it allows them to build a stronger wing with fewer parts.

Yes you can use the measurements and the website, and it works very well. But as a spot check at the field before I fly any plane, I've found using the spar as the check point has been 100% effective.

Brad

Popriv, Do you have this airborn yet?

I have a Midwest Aerostar .40 myself. Got it in 1990, built it and flew it back then as my trainer. Flew it intermittantly over a period of 8 years till I crashed it due to a bad battery. It was rebuilt and mothballed since 1999. I Just recovered it and put gear back into it this past week. I sent an email to Midwest asking about the CG placement. I recall it was on the spar or just in front by 1/4" but I'll post if I get a reply from Midwest. I put all my electronics and battery up front where it was secure just like the first time I flew it. I also put some stick on lead weight on the tail like I originally had. I fly a 10 oz tank in it. Check the cg when it is empty tank and everything else loaded into it.

I flew it this morning in a moderate wind of 10mph for 1 flight just before work. She took off easy and sure did float well on landing. I'm still using the original os .40 ringed engine I had in that plane when I puchased it from the LHS.

So now I know there is at least 2 of these out there still

Hi,
It took longer to finish up than I thought.
Just a few adjustments and I think its ready to fly...
I'm checking out the local flying fields/clubs looking for someone willing to train me...
I'll post a pic of the finished plane tonight.

I think mine is smaller than the 40? I have a 52" wingspan. I've put a TT .36 on it and ran a couple tanks of fuel through it.


Pops

I didn't know they made a smaller one.
Mine's definitly a .40.
CG for the .40 size is 3/16" back from the leading edge of the wing according to the email I just got from Midwest.
I wonder why your aileron difflection is different for up vs. down. you much not have good 90 degree angles somewhere.

Do yourself a favor. Get a cheap USB trasnmitter box and download the fms simulator. Lots of online hobby stores will sell the esky transmitter w/ USB connection to run w/ FMS.
That will save you LOTS of greif in flying and loosing orientation. You should be able to get that for less than $50 online or ebay. search RC simulator on ebay.
Here is a guy that has those:
http://www.jaghobbies.com/images/rc_.../usb_sim_2.jpg
Look for that item on this page
http://www.jaghobbies.com/rc_planes/ek1h-e016a_cart.htm

Popriv,
My first trainer was the Aerostar, great flying plane. That was about 20 years ago.

dditch,
I think your missing a number in front of the 3/16th, I can't remember the wing chord, but it must be 2-3/16th back from the leading edge.

http://www.midwestproducts.com/item_...asp?item_id=38
The CURRENT Aerostar 40
Are you sure that you or someone else hasn't shortened the wings?

[email protected]
You can write these people with any specific questions or to see if they used to make a smaller version. 1-800-348-3497

This was the .25 version of the aerostar. I started building around 1990. I threw everything out but the plane was hanging from the ceiling all this time. I could get the plans for $13 from midwest. All I really would like to know is the CG they recomend.
Everything orange is new. had to make the elevator, ailerons and the nose. The wing tips needed a little repair. I Added a Thunder tiger .36 and I've run a couple of tanks in the backyard.
Bought a Spectrum DX6i and installed servos.

left to do:
Fix binding front wheel when it turns.
How much is enough ? Is 1/4" turn L & R enough?

Rudder is 1/2" L&R

Elevator is 7/16" Up & 5/16" down

right Aileron is 5/16" up & 3/8" down

left Aileron is 3/8" up and 5"16" down

The aileron rods do not align, I missed that in the dry run.. I think thats why the ailerons dont move evenly?
I dont want to twist the rod , I'm afraid they will break out of the wing. I think I can bend them with plyers, after they come out of the wing, so they are the same distance from the servo.
Also I built the box for the servo, It sticks out more than I thought it would?

Weights in at 4.5 lbs

Now I'm trying to hook up with a local club and get someone to work with me.


Soon

Pop

To fix the aileron difference, just screw the clevice onto the control rod more. This will decrease the overall length of the longer control rod and hopefully fix your problem. You could also unscrew the short one to make it longer.

That won't fix the problem. The problem is that the torque rods no not come out of the wing at the same angle. This causes built in undesired differential. Never had to do this before but offsetting the arm on the servo slightly MIGHT fix this. The best way is to correct the torque rods but you would probably break something attempting to do so. Result is that the plane will roll in one direction better than the opposite.

dditch

I think I might have number three, the photos look almost exactly like a trainer a neighbor gave to fly, that he built back in the 80's. He had rebuilt after at least one crash and I am on my second rebuild, first went dumb thumbing and the last was from bad battery. I have found that if you are going to crash, you better know how to rebuild. Currently reworking the wing and installing two servos for the alierons as the wires from the ailerons were bent in the craxsh and could noit be straightened enough to stop binding a pivot point.

By the way, I set the CG at the main spar and it works beautifully.

Rooman

<<<<<That won't fix the problem. The problem is that the torque rods no not come out of the wing at the same angle. This causes built in undesired differential. >>>>>

I dont want to try and twist the torque rods because I agree the wing area will break, I am going to try and bend the threaded part of one rod so they align. I think this will get them closer???


Assuming the rods did line up. It was suggested that I have more up aileron and less down.
If they are both running off the same servo how do you accomplish that?
MY guess?
Right now I'm connecting to the servo AT 9:00 AND 3:00 Oclock.
If I used a round control horn and positioned them at 8:00 and 4:00 oclock....

Would that give me more up and less down?

Or maybe go to 2:00 and 11:00 oclock positions????

Pop

Try this setup to solve your aileron diferential, do not install the rods in the centerline of the servo arm, instead use 2:00 and 10:00

Good luck.

2 & 10 for a high wing and 4 & 8 for a low wing.

1st Flight was a success!

Got a couple of the guys to check the plane out.

Thunder tiger .36 started and ran perfect. balance looked good

One of the guys took the plane up for me and handed me the box.

I flew a bunch of left hand turns. Scared the guys when I held the aileron to long and rolled the plane over.
I got it back under control and they asked if I did that on purpose? Yeh Right.
I lost my orentation a couple of times but got it back.
After awhile the engine died, I had plenty of altitude so I handed the box back and he circled to lose some altitude and brought it in nice.
I would have tried to come right in...Good to see how he handled it.
They said it was built well and didnt need any adjustment.

One of the guys talked to me about exponential. We added 30% to the ailerons and elevator.

Soent most of the day watching.

On my 2nd flight I tried a take off. A little nerve wracking but no problems. Lots of trees at this site so you have to turn left right away.
Controls felt better now, ailerons were not quite so responsive. On my 1st flight it felt a little "twitchy"? or just me with no experience?
I practiced my left turns for awhile trying to line up for a landing. hit or miss for me to make the turn correctly to be lined up on the grass runway and because it was coming at me, the reversed controls were a little much for me. I had a couple of flybys at about 100 feet that looked good. A couple times coming back off line it went right over my head and I got disoriented a bit. this put me over the pits where I wasnt supposed to be but once I turned and was behind the plane again I pulled it left.
No rolls on this flight, I handed the TX back so he could land.

Opps, he handed me the TX and I shut it off. My plane started up and taxied down the runway into the tall grass.
No Damage but a dangerouse thing! Lesson learned!!

I though this wouldnt happen with the Spectrum DX6i ? I think I have to program my throttle to cut if it losses signal????

That was it,

Cleaned up and went home.

I'm going to try another field tommorrow where they have a more structured training program...

But A very good day!
The plane Flew well!
I did a take off and flew.
The plane came home in one piece.


Pop