Mini Q

[Glenn Beer]

Wayne, I know I said this model would wait, and it likely will, but after looking closely at the canopy, I had to work on the fit of it. Basically the canopie needs carefull trimming all the way around to get it to fit the recess.

I did need to remove the springs in order to easily check the fit during trimming.

 

[Wayne]

Yeah, we have alerted the manufacturer to that issue along with several others.

For those that do not know we have a new plane we are testing. We should have one in the air this weekend in glider form at Sunset State Beach.

In case you want to start building this, we have some suggestions from the manufacturer:

ELECTRIC
Motor: 2207 2650 kv
Propeller: 6 * 4
2 s 1200
CG: 25 mm
Throws: A UP 3mm
E DOWN to 5 mm

GLIDER
cg is 5 to 8mm with 2mm reflex (elevons up)

I do not understand the different settings they are sending us, they make no sense to me. glider or power should have the same settings on a plank. So, I'll probably start in the middle, say 16mm or so and start adjusting. Maybe start at 10mm to side on the "glider" setting. I'm told someone in the UK was trying to glide with the 25mm CG and found it tucked. Sounds about right if you have an aft CG on a plank.

The CG will be very important as will the very small elevator throws. Heck, even 3mm of elevator may be too much. Will find out soon enough.

 

[Glenn Beer]

Did they say anything about thrust angles for the motor? The nose is cut at about 2 deg right thrust.

 

[Glenn Beer]

Here’s my reinforcement for the upper surface’s attachment to the center bulkhead.
I still need to bond it in. I may narrow it some if there’s a problem inserting gear.

Maybe the vendor can change the upper surf cutout from one hole to two leaving a bridge.

 

[Wayne]

That's really nice. I left mine as is and fly like that.

The bad news is it took a lot of tests to find a decent CG for the plane. The good news is we found one, and it flew really well. The final bad news is it had a midair and was knocked hard into the ground, so the CG may have shifted slightly. Again, so good news, no major damage. She is tough.. Many a throw into the ground while testing.

I'll measure the CG where it is now and update here. So far she has a pretty far forward CG and needs about 3mm up elevon (reflex) to fly. Make sure you have a lot of trim left for flight trimming. Very small changes make a big difference on this airframe. (Like all planks)

Sorry, they did not give any thrust angles. Would expect it to be the same as any other electric.

 

[Glenn Beer]

ELECTRIC
Motor: 2207 2650 kv
Propeller: 6 * 4
2 s 1200
CG: 25 mm
Throws: A UP 3mm
E DOWN to 5 mm

As I am building the power version. Do I read this right?

Ailerons. 3mm up but no down
Elev. down 5mm but no up

Also it seems strange that the reflex wasn’t built into the airfoil?

 

[Wayne]

We measured the CG on mine this morning, and it is right at 25mm, but I had suffered a midair on the landing, so she went in hard, this may have altered the CG if the battery moved any. Plane survived just fine.

No, you will want up and down travels for the ailerons and elevator throws. I have as much aileron as I can get, and moderate amount of elevator currently. I will suggest you have a switch set up for different weights. But, in general you will have a normal amount of aileron throw.. The elevator will be small inputs once the CG is fine tuned.

The trick to finding the right CG and elevator throw is to adjust one thing at a time. I like to adjust the CG with a small weight taped to the outside. It is easy to adjust. Once I am getting close the the perfect CG, the elevator will become very sensitive and will need to be adjusted for less throw. I have not yet fine tuned mine so can't tell you exactly what and where that is, but we did measure 25mm this morning with a DLG scale that is very accurate. This little plane it hard to get an accurate CG rating. It does not work with our current digital CG scale due to the very small measurement.

-Wayne

 

[Wayne]

Yes, it would be nice if they had used a reflexed airfoil.

 

[Glenn Beer]

I did watch the vids on the tjirc website. With the recommended motor it’s wicked fast.

 

[Wayne]

Even without it seemed to be doing well. Get it a little more dialed in and it should be sweet.

 

[V0cnorth]

Any chance of a pic of your control horn/aileron linkage please.

 

[Wayne]

I'll try and get you a picture tonight.

 

[Glenn Beer]

Here is a pic of mine. Drilled two holes at the spacing needed for the slot then carefully trimmed between them. Epoxy as needed. I should have used a longer horn in the aileron. I did need to add blue thread locker to reduce the play.

I

 

[Konrad]

How has the use of only thread locking compounds held up over time?

I'm old school, with metal clevises I like one clevis brazed (silver soldered) to the shaft and I use a jam nut with the use of thread locking compounds. OK, this comes from the days when I has a spinning prop going about 40K rpm.

Has the edge margin on the servo arm been compromissed?

Edit:
(Lets try the english spelling of margine)

 

[Wayne]

As I recall I just used some music wire with z bends and then added a drop of thin CA to tighten the gap at the control horn. Quick and easy.

Dave stopped by yesterday, he won the plane at the Sunset raffle. He has been flying it in slope trim for a bit now and reports that he really likes it. It flies fast and tight. I've heard from others that have seen him flying it also, and they all seem impressed too. Dave is a good pilot. He does report that he ended up with the same as me, some up elevator is needed, maybe 2 or 3mm up at the trailing edge. Then she flies great. He reports that his finger CG test is about the front of the servo bay. LOL

 

[Konrad]

With surface reflex do you guys bias the servo arm aft? This is to get a better feel while inverted. I find that for non reflexed airfoils I like the down to have a larger and faster input (elevator differential). Unfortunately this result in aileron differential that is reversed from what I find as desirable. I then try to get the desired aileron differential using the radio's programing power.

 

[Konrad]

I try to go into more detail in this thread, see reply 21. It is dealing with a delta wing but all the concepts are the same for a flying plank.

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An Error Has Occurred!

www.hippocketaeronautics.com

 

[Glenn Beer]

How has the use of only thread locking compounds held up over time?

I'm old school, with metal clevises I like one clevis brazed (silver soldered) to the shaft and I use a jam nut with the use of thread locking compounds. OK, this comes from the days when I has a spinning prop going about 40K rpm.

Has the edge margine on the servo arm been compromissed?

The threads will take some looking after to see if they move.

There is no binding against the servo arm as the travel exceeds that needed to move the control surfaces.

 

[Glenn Beer]

As I recall I just used some music wire with z bends and then added a drop of thin CA to tighten the gap at the control horn. Quick and easy.

Dave stopped by yesterday, he won the plane at the Sunset raffle. He has been flying it in slope trim for a bit now and reports that he really likes it. It flies fast and tight. I've heard from others that have seen him flying it also, and they all seem impressed too. Dave is a good pilot. He does report that he ended up with the same as me, some up elevator is needed, maybe 2 or 3mm up at the trailing edge. Then she flies great. He reports that his finger CG test is about the front of the servo bay. LOL

Servo bay = servo hatch opening or hatch cover ?

 

[Konrad]

...There is no binding against the servo arm as the travel exceeds that needed to move the control surfaces.

Is this in response to the edge margin question? My concern is that it looks like the arm cracked when shortening it, leaving little material between the hole for the clevis and the edge of the arm (edge margin). I'm concerned the the clevis pin could pull through the servo arm if there isn't sufficient material.