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

[Konrad]

Initial AUW is 2.53kg with 330g of that being nose weight at a CG of 95mm. I’ll need to read through this thread to see what the AUW is for models with the servos in the nose. ( I read in this thread that another Alpha 2.8 came in at 2.550kg (90 oz in old money). This was with 2 servos in the nose, the CG @100mm and no ballast tube)

 

[Konrad]

As a machinist and engineer I knew better than to try to remelt Woods metal lead. Why do I keep showing my mistakes. I know so that others can learn from them and NOT repeat them.

If you are a welder of do any furnace brazing you know that Boron is used to lower the melting point of materials. You also know that subsequent melting points will be higher as each successive reheating drives off a lot of boron. Here is proof. The first heating of the Woods metal lead melted at about 180°F. (Well below the 212°F of boiling water) It cast beautifully in the nose of my Alpha 2.8m glider. I had calculated that I'd need 270 grams of mass to balance the Alpha 2.8 at 97mm. I checked the balance point and found I was short in that the model balanced at about 99mm to 98mm. As I had some Woods metal still in my casting ladle, so I reheated it and poured it on top of the first pouring. You can see the results. It looks like the second melting was above 451°F by the charing of the wood!

 

[Doc James Hammond]

Looks like a bit of a weighty problem.

Doc.

 

[Konrad]

I've trained the servo wires, put the antennas in there tubes, added the Zepsus switch, fitted and added the covers. Basicaly cleaned up the model ready for the maiden flight. But now the wind gods are laughing at me, as it looks like there won't be any wind for the better part of a week. This might force me to accomplish some paint repairs.

The good news , if one can think that way, is that the Feb 20th F3F has been moved to Feb 27th. By then I should have six 3 meter ships ready to fly, maybe even race!

 

[Konrad]

Well I just came back from maidening my carbon lay up Alpha 2.8 meter slope glider. I have to say I now have a new favorite 3 meter class glider!!! She is all I hoped she would be. I love the power in all flight axises and configurations. I can actually perform pumps at Thornton Beach.

Because of the narrow compression zone most guys use a lot of rudder at the top of the zoom to stay in the compression zone. The Alpha has a strong enough rudder to do this with easy. (My Strega's and Redshift's not so much).

Rolls are good to great as I don't need excessive differential to keep the the nose on heading. They're not as snappy (initial roll) as the glass Redshift. But this is to be expected as the Alpha 2.8 is a lot heavier. This mass does dampen all the axises.

The only negative set up I can find is that I need about 85% down comp with the flap fully extended. I'm thinking I may have to add a bit more up to the ailerons in crow to balance out this.

Now I maidened this Alpha 2.8 at the same time I maidened my glass Redshift. WOW, what different ships these two are. The Redshift is like the thoroughbred horse. The Redshift is a much faster and harder turning ship in the same lift for a host of reasons. But the Alpha 2.8 is a much nicer handling honest easy to fly aircraft! Now unlike the Redshift I could hear the air scream trying to get out of the way when I got the Alpha 2.8 really moving fast. Some folks might like that. But I think that is an indication of unnecessary drag. (It might be one of the reasons the Redshift is faster).

The only mark against this model is that the Great Wall looks too much like she is sporting the Russian colors. That has to change! But the Alpha 2.8 livery actually looks rather nice.

When I find a ruler I'll post my control set up. But in the mean time get your own Alpha 2.8m if you are looking for a great 3 meter V-tail sport ship.

I would like to thank Wayne at Aloft Hobbies for the good deal on this shipping damaged aircraft. The servos in the tail are worth the effort! (Thank You @Redbird )The old KST wing servos are more that adequate running off the MKS voltage regulator. While I have a ballast tube installed I haven't flown with any ballast.

 

[Konrad]

LOL!

I stepped into Aloft Hobbies to a standing ovation over this report of my maiden flight. Wayne said he can't recall when I had such a positive opinion about a model.

While I admit I try to be critical,* I do think I give my model write ups a fair assessment. Heck, I really liked my Samsara for what she is.

* If you want a love fest or be part of a mutual admiration society take a look at RCGroups. It often takes pages and pages to find anything that might not be friendly to the advertisers.

 

[Konrad]

I was a bit surprised at how embarrassed I was to fly the Russian colors. So since I had to mix up some paint for my Yellow Strega I took care of the issue!

 

[Konrad]

Here is what I found on the airframe after the maiden.
The AUW is 2.53 kg (89oz) with the CoG at 95+ mm
Elevator is 6.6mm each way.
Rudder is 10.7mm each way.
Ailerons up 11mm
Ailerons down 7mm
Flaps as aileron about 2/3 that of the ailerons.
Climb flaps 5mm down (elevator comp 1mm down)
Reflex 2mm up
Crow flaps 85° ailerons up 5mm, elevator 4mm down.

 

[Konrad]

Here is a Synopsis of what I found durring the build.
1. I'd like to see the wing box and spar joined in a more positive manner. (see post# 105)
2. I'd like to see the carbon start in the nose at about 50mm before the cone part line. And replace the carbon in front with a layer of Kevlar going back to the LE . (see post# 16)
3. I'd like to see a larger bucket for the nose weight. (see post# 142)
4. I'd like to see the servo tray extend past the leading edge of the wing. (see post# 106)
5. I'd like to see the V-tail mount fleshed out to allow for control arm clearance (see post# 90)
6. I'd like to see the model built with industrial adhesive (see post# 53)

Please remember this is an early production "Great Wall".

 

[Konrad]

Well painting didn't work out well. To save weight I did not use a sealer. I put down PPG Delfleet Essential top coat directly on the sanded surface. Only to find that the TJIRC red pigment had floated through the paint.

 

[Konrad]

To my heart and soul she is looking much better. No need to wear a Groucho Marx disguise when I fly her.

 

[Wayne]

Speaking of Ukraine (almost) I just got an email from our DLG manufacturer and he sent me a receipt for our shipment! Wow, he is over near the Russian border and he is able to ship? He may have moved to a different area, no idea. I'm amazed he was able to ship anything, let alone big boxes full of yummy planes.

 

[Konrad]

Here is how I set my antennas. I also converted the loose lead weights to Woods metal lead for a cleaner installation.

 

[Doc James Hammond]

Here is how I set my antennas. I also converted the loose lead weights to Woods metal lead for a cleaner installation.
View attachment 10838

I always do the ballast shotgun style from the bottom, but I suppose the insolated ballast tube is stronger.

Cheers,

Doc.

 

[Konrad]

This is a bottom feeder (AKA lawyer). (As shown the bird is upside down) So the shot gun loading is from the bottom and the slip on nose cone holds the flexible blank in place. I think I got that idea of using a flexible blank from you years ago. This tube is bonded by its full length to the fuselage to stiffen the fuselage, particularly along the wing saddle area.

 

[Doc James Hammond]

This is a bottom feeder (AKA lawyer). (As shown the bird is upside down) So the shot gun loading is from the bottom and the slip on nose cone holds the flexible blank in place. I think I got that idea of using a flexible blank from you years ago. This tube is bonded by its full length the fuselage to stiffen the fuselage, particularly along the wing saddle area.

Aha! I stand connected.

Doc.

 

[Konrad]

It is with a heavy heart that I must report the demise of my Alpha 2.8. She left us far too soon with only about 2 dozen flight/landings.

I think it very important that we all learn how the structure performed. What follows is not for the faint of heart. I will say that I was impressed at how the structure performed. This was a pleasant change from what I've dealt with from the OEMs like RCRCM and Zhou (DBA RGMCN ?).

The aircraft was ballasted to around 65 grams / SQ DM. She fell about 150 meter straight down into the soil pile at the base of a cliff. The impact trough was about 10cm deep and about 2 meters long. Please note that this long an impact zone did lessen the impact shocks.

The fuse broke into three pieces. One break was mid tail boom and the other was at the wing joiner pass through window. You will note these aren't the typical failure points just behind the wing and just ahead of the leading edge. This shows that the servo tray and ballast tube supported the front of the fuselage more than adequately. The mid boom failure indicates that the boom was a good balance between strength and weight. (Note the boom had 4 large carbon ribbons going down its length. It wasn't 100% carbon as indicated earlier)

Now what was odd to this crash was that the rear part of the fuselage was found imbedded in the wing spar (inside the wing!). Also the ballast exited the rear of the fuselage. But the nose was found deep in the ground.

The V-tail was undamaged. Normally the pushrods with the weight of the servos will tear off the elevators. With the servo in the stabs this did not happen.

The wing joiner plowed through the front of the wing box and exited through the LE. The left wing made contact with the ground first with the LE of the tip being crushed. Note that nowhere along the span of the spar is there any delamination. Also of note is that none of the surface hinges failed.

While I'm sad to see my ALPH 2.8 die, I'm impressed at how well the airframe performed in a crash. This goes to reinforce my opinion that TJIRC has no rivales at this price point. Buying models from RCRCM and RGMCN has proven to be an utter waste of money.