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Alpha 2.8 TJIRC (AKA, TJIRC Great Wall 2.8m)
- Thread starter Konrad
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- alpha 2.8 f3f great wall tjirc
Konrad
Very Strong User
Thank you. That photo made me rethink the CG!
Per the Aloft web site the CG should be set at 90mm. But looking at my wing ballast port it looks like TJIRC thinks the CG may be nearer 105mm.
Add to this that my RCRCM Stregas balance best at 110mm to 115mm. It is looking like the ballast tube I was showing is going to be too short for shot gun loading.
Has anybody here actually flown an Alpha 2.8 and can they report on the CG? I'd like to find the tuck point as defined by the dive test. I'd also like to learn where you actually place the CG. A CG range of 25mm (90mm to 115mm) is a bit too wide for placing the ballast tube.
P.S.
Yikes, I found a report on RCGoofs that a guy has set the CG in the middle of the joiner bar. By my measurement this is 75mm! Adam is a competent builder and flier, so now I'm really lost as to the CG.
Per the Aloft web site the CG should be set at 90mm. But looking at my wing ballast port it looks like TJIRC thinks the CG may be nearer 105mm.
Add to this that my RCRCM Stregas balance best at 110mm to 115mm. It is looking like the ballast tube I was showing is going to be too short for shot gun loading.
Has anybody here actually flown an Alpha 2.8 and can they report on the CG? I'd like to find the tuck point as defined by the dive test. I'd also like to learn where you actually place the CG. A CG range of 25mm (90mm to 115mm) is a bit too wide for placing the ballast tube.
P.S.
Yikes, I found a report on RCGoofs that a guy has set the CG in the middle of the joiner bar. By my measurement this is 75mm! Adam is a competent builder and flier, so now I'm really lost as to the CG.
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Do you guys note this model being reasonably capable of consistent tight-ish field landings? I know pilot skill is 75 percent of pulling anything off. I believe my skills are adaptable and solid so long as I'm not trying to pound a square steel pin peg into a round steel hole 
I'm looking for a light to medium lift sloper in the 2 to 3m size to work beach slopes along the Monterey coast. Perhaps I should also consider a smaller airframe for that. Cheers!
I'm looking for a light to medium lift sloper in the 2 to 3m size to work beach slopes along the Monterey coast. Perhaps I should also consider a smaller airframe for that. Cheers!Hi
No problem, I'll tell you the CG this we.
You will see the pictures of the antennas but you'll be disappointed ? I will try to look at the telemetry data but I've never heard an alarm.
Konrad
Very Strong User
Eddie the Alpha 2.8 will fly the glider port at Sunset Beach just fine. Almost all the short field landing work will be determined by your ability to control drag. This means your gliders should be able to perform crow. This means in your radio programing you allow the ailerons to go up 30° to 40° and the flaps come down 70° to 90°Do you guys note this model being reasonably capable of consistent tight-ish field landings? I know pilot skill is 75 percent of pulling anything off. I believe my skills are adaptable and solid so long as I'm not trying to pound a square steel pin peg into a round steel hole
Ok, with that said, the Alpha 2.8 is not a light air ship in the vein of the Ahi. It is a medium lift to strong lift ship.
As a general rule I like larger ships for light lift, bigger flies better.
Aloft Hobbies has many gliders in the 2.4m and up sizes that would work real nice for light costal slopes.
Now ships on the small side I love the Mefisto.
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Konrad
Very Strong User
2-56 if you are still using old school units. These aren't DS ships. Modern ships should be using metric standards, 2mm would be more than adequate. Du-Bro sells 2mm threaded push rods, this makes it easy to fit other hardware we use in the gliders.
I'm fitting IDS in the wings. I love that I don't have to remove factory installed control horns. What issues are you seeing.
Have you seen this thread?
I'm fitting IDS in the wings. I love that I don't have to remove factory installed control horns. What issues are you seeing.
Have you seen this thread?
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Well it’s super tight with the x10s. All servo arms would have to be flush because they don’t fit in the groove with the supplied servo covers, ids arm is 3x wider than traditional clevis. I am concerned I wont get enough movement on my flaps. I find that’s it’s got to be super difficult to get the servos in with the bearing once everything is glued into place. Never used ids before. I understand I would need to notch a little for screw access but I don’t want to take away too much material on the wing.
One antenna is horizontally, on the right, along the servo and the other one is vertically, in front of the receiver.
I had to quickly change my servos but I will make the installation more clean later.
For information, I have a GPS in front of the servos. The signal is long to be clear but I have some satellites after a few minutes.
Have a good day
Gabriel
Konrad
Very Strong User
Notching the wing to clear the 30mm x 35mm servo mount is normal. The OEM doesn't know what brand of servo you are going to use, so they leave that up to us. Notching the 35mm dimension will not weaken the wing. Notching the 30mm dimension will have a negligible effect on wing strength. This is an issue with servo mounting not the IDS.
Now your point about maybe needing a jelly bean fairing to clear the IDS arm is well taken. I find it is easy to make a wide jelly bean cover by laying up glass on a waxed sheet of glass. See my post here.
I've found that I need to use the shortest IDS arm for the ailerons and the second shortest for the flaps. Rarely do I need to go up to the third shortest. Give a scan of my Redshift and Strega threads to learn more of my issues and solutions with installing the IDS.
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Konrad
Very Strong User
Gabs, Thank you 97mm to 100mm helps a great deal and is in line with what Aloft published as a starting CG of 90mm. Do you use the wing ballast? If so do you have to use a trim box to correct for the 105mm location of the ballast box?
Konrad
Very Strong User
Thank you I too try to set up my antennas at 90°
Redshift; Used Purchase
The flippers are now ready for paint. Ok, primer. I have to say that when I took on this project I didn't think it would come out as well. Nor did I think it would take as much work as it did. I'm now very happy with the airframe. All that is left is the actual test flying and follow up...
forum.alofthobbies.com
I have not yet used the ballast. I have to adjust the tube I bought to fit in the 19mm ballast tube but I couldn't change the ballast location on the great wall.
Started cutting for IDS, Konrad I check the drawing from Doc looks like horn should be mounted like pic#1 if I’m correct? Want someone elses input before I start epoxy these in.....
Attachments
Konrad
Very Strong User
The drawings I made in Doc's thread do show this but I want to be clear. You will in all likelihood need to remove the top skin core (Balsa or foam) leaving the very top layer of the carbon.
forum.alofthobbies.com
Yes, it looks like you have the correct spoon and rod orientation.
The spoon offset look backwards the pin hinge should be towards the upper wing skin, giving you a longer control horn (distance from the hinge).
The rod looks correct to the wing. The stiffening web should fit into the slot in the control arm
Composite control drive installation
I just spent the better part of a day grinding out legacy control horns from my modern composite ship. I’d like to learn why composites ships haven’t fully moved away from the classic control horn we first became familiar with way back in the days of balsa wood models? I see an opportunity to...
forum.alofthobbies.com
The spoon offset look backwards the pin hinge should be towards the upper wing skin, giving you a longer control horn (distance from the hinge).
The rod looks correct to the wing. The stiffening web should fit into the slot in the control arm
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