Alpha 2.8 TJIRC (AKA, TJIRC Great Wall 2.8m)

[Konrad]

OK, I'm jumping ahead to the IDS installation. Here I'm showing that the servo needs to be placed so that the push rod is 90° to the hinge line. I'm also finding that a push rod length of 63mm appears to be a good length. I think it will be ether the 63mm or 60mm rod length.
(Edit: 66mm looks to center the flap servo best in the flap servo opening. 51mm push rod works well for the ailerons and the use of the IDS)

 

[Ryanenc89]

I knew my first time was going to be rough installing ids, took me 6.5 hours to do the first wing and about 1 hour to do the second. My neck is cramped but glad how clean it came out.

 

[Konrad]

Looks fantastic, nice clean work! It appears that the servo arms are inside the skins. Since you are the trail blazer can I ask what hardware you used, arm and pushrod length?

 

[Konrad]

I like to try to leave much of the servo cover flange and just radius the opening for screw drive clearance. This means that I often have to fish the servo tray in and out of the pocket. Here with my Strega install I tried to move the servo as far forward as possible to try to get the rear of the servo inside the wing skin.

I've recently learned just how important it is to tie the wing skins together. To do this I made up a slurry of Epoxy and Cab-O-Sil and made a shear web with the bearing boss and lower wing skin. With glass wings, this made a huge improvement in the centering of the flaps!

 

[Ryanenc89]

Servos and arms/rods are all flush. I used the 3rd smallest servo rod for aileron and 6 for flap. Second servo arm are for aileron and 3rd servo arm for flaps. The Aileron was a little difficult to glue in the horn at the correct angle, note it is not 90 degrees of off the hinge line. I only cut 1 side of the servo pocket and very little sanding on the trays to get them to fit in as one piece before epoxied in.

 

[Konrad]

Thank you! It looks like you got the servo centered rather well in the pocket. This will force me to rethink my push rod length. (I'm currently thinking that #5 (60mm) from the bottom was going to be a good fit).

 

[Konrad]

Now I do this so you don't have to!

As I was going to have to paint my nose black I saw no harm in inspecting the fuselage at the known RCRCM manufactured failure point.

After my poor experience with the management at RCRCM involving my Strega's and the manufacturing gap in the carbon stiffener. I decided to inspect the fuselage of the TJIRC Alpha 2.8.

Again I was pleasantly surprised at the quality of the fuselage. The fuselage has at least one layer of carbon 360° aft of the fuselage. There is even some heavy carbon doublers in the lay up. I was also surprised at how good the wet seam was in the part line for a ship at this price point!

 

[Ryanenc89]

Worked on the stab fins for a little bit. I was worried about being a large gap in the tail needed for linkage to pass through, it came out clean and not that noticeable. First screw up I managed to poke through the top skin barely. I might try to fill or just leave it, wish tjirc made the stabs as strong as the wings, Im pretty sure they made this upgrade on the Magnus.

Positive note I can get full 90 degrees on flaps and have way more throw on ailerons than I’ll ever need. I really like the way ids has turned out, minus all the bs of trying to fit everything the first time.

 

[Konrad]

I actually like the light tails. I much prefer that TJIRC place their weight credits towards a much stronger tail boom than heavier stabs (stronger skins). This is not a DS ship. The stronger Magnus carbon stab is actually a detriment until one starts to reach 200 mph. More stab weight puts more load on the boom and needs a lot more nose weight to balance.

Yep, that is why every IDS install I use the shortest arm for the ailerons. I want to maintain the power and servo resolution as much as possible. I can tell you they get easier and easier to install until there is a change in design,then one needs the think a bit. But you already have the basic concepts down. So it isn't too bad.

How long are the control horns on the stab (hinge line to sphere center)?

 

[Ryanenc89]

If I’m understanding you correctly center of ball lands right around 8mm, if you can manage to get 9mm on both side I think that would be a little better. Anything pass 10mm might have some rubbing issues.

 

[Konrad]

I was concerned about the height above the hinge. With this short a control arm I like to use threaded 90° push rods. This allows for 4mm to 5mm servo arms to help use the power of the servo and keep up the resolution on the surface. These are both needed at speed!

A limitation of V-tails is that you can only use 1/2 the servo motion (resolution) for the elevator and the other 1/2 is for the rudder.

 

[Konrad]

On this page Jonathan Wells goes into a bit of detail on how he makes his threaded 90° push rods.

 

[Konrad]

I hate to do this, but in the spirit of full disclosure I have to post the flaws I find.

I need to make it clear that this model is at least 2 years old. I know that with every production run I see from TJIRC the quality of the model improves noticeably. I also know that Wayne at Aloft is working with TJIRC to gives us better models. Not only in selection but also in quality.

Now when Wayne gave me (well almost gave me this) he asked that I do a thread warts and all. I was a bit surprised by this request as the Great Wall is not the exact same model we get with the Aloft Alpha 2.8. There is 2 years of development between what I got with the Great Wall and what you'd get with an Aloft Alpha 2.8m.

With that out of the way, here are a few warts that I've found. First the wipers are about 3 times thicker than they need to be. This often is just a problem with the experience level of the builder. This really isn't a make of break kind of issue. In my case it was a bit of a problem in that the wipers did not allow the IDS spoons to meet the surface of the wiper. It was easy to fix with a ball nosed burr to thin the wiper to allow the spoon to seat properly. (Please note that with the classic horn and clevis push rod this would not have been an issue).

Now I did find some delamination in the TE shear webs and the shear webs found in the flaps and ailerons. This can be traced to two issues. First is that the shear webs are too narrow (short). The adhesive bead never made contact with the upper shin when the molds where pressed together. This is a problem with this kind of construction. If the shear webs are too tall we complain that we can see the sub structure pressing into the shin's upper surface. If they are on the small side we complain that there is too much adhesive used and that our wings are too heavy.

The second issue is that the adhesive is a bit too dry. This results in a very poor bond as there is almost no wet out in the joint between the two parts.

These delamination should be easy to fix as I'll be adding low viscosity epoxy to the shear webs in hopes of improving the bond. Heck, if I can get into the areas I might add an epoxy fillet to the shear webs and the skins. Yes, this will add weight, but I'm always add ballast so it should be a minimal penalty.

All the best,
Konrad

 

[Konrad]

Here I'm trying to document some of the issues I had with installing the IDS spoons. The key was that the wipers are a bit too thick. i needed to locally thin the wiper with round burr to allow the spoon teeth to clear. Allowing the IDS pin to be placed properly above the hinge.

 

[Gabs]

Hi,
Bad news, I crashed today my Greatwall. Dead of the lipo at the end of my flight, the glider was in descent at 45° during 60 meters. It is very strong, because only the joiner is knockout. The fuselage is quite ok, just some little repairs to do and the skin of the wing, near the fuselage, where the pawns are fixed. We were very impressed to find the glider not so bad after this dive.
Do you know where I could find the joiner?
Have good flights, with a good battery

 

[Wayne]

Send us an email at: contact@alofthobbies.com
We can order up the joiner for you, will have to get the price, but think the price is very reasonable. They should be able to slip it into our next shipment, they are currently boxing that one up, so don't wait too long.. We call the Plane the Alpha 2.8.

 

[Gabs]

Hi. thank you
I sent you an email.
It would be great if it could arrive soon
Have a nice day
Gabriel

 

[Ryanenc89]

Well the plane has been finished for a couple weeks now, went to maiden my 2.8 on Sunday but the wind was pumping 40mph+ with a nasty rotor at the LZ I opted out decided to wait for a lighter day. AUW is 90oz and CG set 101mm. Enjoyed hours with the Magnus whick took a fall from about 20’ landed upside down after getting sucked into the rotor only couple small scratch’s.

 

[Konrad]

This question isn't aimed at anybody in particulare. Why use a small servo tray? I'd think that our models would benefit from full length servo trays. I'm of the opinion that these add a great deal of lateral strength to the nose. If you have seen my landings you know that the nose needs as much help as I can give it!

My Great Wall came with a 3/4 length wooden servo tray. I assume that the small fingers going on each side of the battery might not be worth the cost in materials. In my Strega (canopy opening) and Redshift (slip over nose) builds you can see that I used full length servo trays. I recall that the Strega came with that little wooden postage stamp sized tray and the Redshifts came with a full length fiberglass servo tray. Not sure what comes with the Alpha 2.8 branded model.

 

[Konrad]

Working the fuse with some sandpaper. I noticed that the molds for the Alpha 2.8 look to be made old school. That is they were pulled from a plug using a parting board. It does not look like these where made from a CNC cut master.

The center line had a very small radiused ridge typical of what we'd see with sealing a parting board when making the mold from a plug. You can see the nice even seam from where I sanded down the ridge.