ALOFT: AH-100 Build (new title)

[G-man]

G-man has built the Riser combo, plus an OLY2 version. and put them both thru their paces.

More info on my OEM PRELUDE wing, and RISER-100 wing on PRELUDE fuselage is here:

ALOFT: Sig RISER-100 wing on Topmodel PRELUDE fuselage

The quality of my first Topmodel PRELUDE project fuselage, plus the service and support from Aloft impressed me so much that I ordered a complete PRELUDE kit; this time the PRELUDE REF (Rudder Elevator Flap) version...

forum.alofthobbies.com

 

[Wayne]

Great to hear from you.

So here is a conversation we have been having here. Why is the Oly II wing fluttering? Looking at the designs of these 3 wings they are all pretty close. The Oly uses a spruce leading edge and a spruce spar caps and balsa sub spar. It should be a pretty strong combination. With this said it does not have much for gussets and is a rather minimal structure. The leading edge is rather small.

Then we look at the Riser and it has a little larger spruce spar caps and balsa "turbulators" and I think it is a hardwood dowel for the leading edge. I do think the 3 turbulators act a bit like a sheeted D box. This is our best guess. I also like that SIG slots the trailing edge for the ribs to glue into. This will help too.

The Pussycat is rather similar to the Riser, but does not have the third turbulator and uses an "arrow shaft" for the leading edge.

I flew a lot of the 2 meter Wanderers back in the day, and they had even less structure. They use a simple 1/4"x1/2"spruce spar, and a 1/4"x3/8"spruce sub spar that only extended 5 bays into the main panel. The rest was balsa, no turbulators, no tricks on the leading edge, no sheeting except in the center section. No flutter at all! I flew the thing inverted on the slopes as a kid.

I see there is a 99" Wanderer. News to me. Looking at the plans for that, it has a rather substantial wing. Bigger 3/4" spar caps, a sub spar and hardwood turbulators. That 3/4" spar caps must have been fun to try to blend into the airfoil.

 

[Wayne]

OK - I think I'll need to order in some 1/8"x3/8" spruce for the spar caps. We do not currently stock this size, but think that little bit extra is decently important as it looks like all of the other plans of this area and size are running a little wider spar caps then I have specd out. (I am same size as the Oly right now.)

 

[G-man]

Let me know what you hate and what you like.

1. I sure like the COMB just behind the LE.
Works as a turbulator spar, adds stiffness the length of the wing, and lets the sun shine through transparent covering.

2. I prefer STRAIGHT wing joiner rods.
It matters not to me whether they are steel music wire or CF rod, but I want to avoid fiddling with joiner rotation in the field.
Over the course of the four OLY-2s I built I saw the steel wing joiner rod increase in diameter twice.
But that was to cope with stronger and stronger winch launching.
With the motor in the nose, our launches and climbs are much gentler, if less exciting.

3. I'm glad Wayne and company are paying close attention to wing dihedral and polyhedral angles.
I haven't figured a way to measure the dihedral and polyhedral angles of the planes I like to fly,
but re-reading Pete Young's OLY-2 hints and tips I m persuaded that a SHALLOWER dihedral angle
is what we want. (Pete recommends using HALF of the OEM spec.)
I would try it on my current RISER-100 wing if the brass receiver tubes for joiner rod (1/4 inch music wire) were not already installed.

It sure is cool to be a participant in the design process.

// Dave

 

[Wayne]

Totally agree with straight wing rods!! Hate bent round rods. I once had a plane that had 2 bent round rods parallel to one another. You want to talk about a royal pain to put that wing together.

The down side of a shallower diehederal angle is the rudder will be less effective.

Do you have a smart phone with a "level" app? Just lay one wing flat on a level surface and sit your phone on the other wing panel. Do this for the main panels, and do it for the outer panels. Let me know what you get.

 

[G-man]

My phone is not quite that smart.
I'll see about borrowing a smarter phone.

Glad you understand about the frustration of rotating the bent, alignment-critical wing rods.

 

[G-man]

Why is the Oly II wing fluttering?

There is the change of formulation for genuine TOPFLITE MONOKOTE to consider.
My first three OLY-2s with genuine MonoKote in the 1990s - no flutter. Never noticed flutter. Three pilots did not notice flutter. (all yellow covering)
My fourth OLY-2 with genuine MonoKote purchased after 2010- slight flutter on slight dive, repeatable. (marked with "4" on the wing)
Sig Riser built in early 2023 covered with transparent red "Chinacote" that matched the tail parts - NO FLUTTER. (red covering)


I do think the 3 turbulators act a bit like a sheeted D box.

I agree. And you know I like letting the sun shine through, so prefer the three turbulators over a D-box.
Your front COMB solution is wonderful.


I also like that SIG slots the trailing edge for the ribs to glue into. This will help too.

Good observation. Notches in the TE stock must help rigidity, and alignment.


I flew a lot of the 2 meter Wanderers back in the day, and they had even less structure. ... No flutter at all! I

I was wondering how a high performance guy like you happened to have a warm spot in his heart for floater gliders.
Now I know - childhood memories.

I have read the observation that the 2 meter Wanderers "flew well even if poorly constructed."
- Wow. Very cool if true. Kit makers must love this characteristic. It invites new builders.
- Is this a design consideration for us on the current project?
- How do you create that characteristic?

The COMB in the front and TE notches should help with rib spacing and alignment for more accurate construction

 

[G-man]

Sandman> A lighter wing design would complement the light weight Prelude fuselage.

Right you are, it's quite light. and plenty stiff.
It's also longer than Oly-2 and Riser-100 kit fuselages. (smoother in flight?)
The full-flying horizontal stab banishes troubling decalage questions.

 

[G-man]

WAYNE> I think I'll need to order in some 1/8"x3/8" spruce for the spar caps.

Gotta love call-outs on the construction drawings.
Remember when the instructions for building were the call-outs and a couple paragraphs on the drawings?

 

[G-man]

RAYMOND> Do you have any more of the Top Model Prelude fuselages in stock?

One in stock as of now.
more coming, I believe.
// Dave

TopModel Prelude 2.5m Fuselage

Need a new fuselage for your TopModel Prelude? Well here's a fresh one. You may also want the canopy, elevator bellcrank and elevator and rudder assemblies. We also stock these parts.

alofthobbies.com

 

[JohnT]

Totally agree with straight wing rods!! Hate bent round rods. I once had a plane that had 2 bent round rods parallel to one another. You want to talk about a royal pain to put that wing together.

The down side of a shallower diehederal angle is the rudder will be less effective.

Do you have a smart phone with a "level" app? Just lay one wing flat on a level surface and sit your phone on the other wing panel. Do this for the main panels, and do it for the outer panels. Let me know what you get.

Got my wing out and have a very close measurement for you.
Inner Panel, with one flat on the floor, got a hair over 4 degrees. Margin for error could be 1/2 - 1 degree, due to spoiler servo cable exiting underneath.
Outer Panel, with inner panel flat on the floor, came out to be about 3 - 3-1/2 degrees.

Cheers!

John

 

[Red]

Got my wing out and have a very close measurement for you.
Inner Panel, with one flat on the floor, got a hair over 4 degrees. Margin for error could be 1/2 - 1 degree, due to spoiler servo cable exiting underneath.
Outer Panel, with inner panel flat on the floor, came out to be about 3 - 3-1/2 degrees.

Cheers!

John

Are my eyes playing tricks on me or are the tip on backwards?

 

[JohnT]

Er, uh, uhm, well . . . it's a new aerodynamic lift producing tip extension that I'm experimenting with.

Just remember, we don't need no stinkin' fancy wingtip!

John

 

[JohnT]

I shall call it Secondary Tip Uplift Producing Independent Dragless Aerodyamics©

 

[Sandman]

I like the aspect ratio of the Sig Riser wing, which has a chord of 10 3/4", what is the width on the OLY2
I also like the comb behind the LE.
Straight wing rods is the ticket.
Not to get ahead of things, but another design aspect will be how we mate it to the Prelude fuselage.
What does the stock Prelude wing/mounting arrangement consist of.
G-man has a set up (Trailing edge bolts/leading edge pins) that mates the Riser wing to the Prelude fuselage.
Could we make the new wing design utilize the same mounting holes as the Riser set up.?

 

[G-man]

I like the aspect ratio of the Sig Riser wing, which has a chord of 10 3/4", what is the width on the OLY2
The width of my OLY-2 chord for the inner panels is 10.0 inches.

Not to get ahead of things, but another design aspect will be how we mate it to the Prelude fuselage.
Might as well begin to think about it, and gather ideas.
Attached are photos of my first and third improvised wing mount.
(The second one was lost in the Canadian wildfire smoke and haze.)

Could we make the new wing design utilize the same mounting holes as the Riser set up.?
That will be for someone other than me to answer.
But while the stock Prelude wing has factory holes for bolts, the fuselage has none.
The bolt receiving holes and their plywood backing must be located and installed by the builder.

My design, with pins in the front and nylon bolts in the back:
- So far has proven strong enough for the purpose intended.
- Assembles and disassembles quickly, and without the use of tape.

The builder must install the pins and bolt head hard points before closing up the first bay.
I'll cover my method to do that in a build thread to be started shortly.

 

[Wayne]

All of the designs we have been studying are rubberband attached wings.

One could simply add some dowels to the Prelude and continue in that fashion. But I'm guessing this is not of great interest. Why mess up a pretty fuselage with dowels and rubber bands? (Longevity of the wing would be a valid reason.)

So adding some hard points and pins is a possible solution. Probably the best solution. We could make it a bit fancier and have a 3D printed stucture that handles all of the bolts, pins and spar and this would also have a little fairing at the leading edge to fuselage connection. But that is probably getting a little complicated. Perhaps just the fairing, and leave the rest in wood.

We will be using a 3D printed assembly for the wing joiner. It will be 100% inside the wing and not visible. We have found this method to be very robust and makes the build easier. It simply glues into the spar caps and has all angles already built in. No brass tubes etc. We have used this method on our 3.8 meter all wood thermal glider D'light.

I'll adjust the dihedral angles and see what you all think a bit later today.

 

[G-man]

Perhaps just the fairing, and leave the rest in wood.

The Topmodel OEM canopy makes a pretty good fairing over the forward pins.
A little bit of grinding and sanding is needed to clear the fatter airfoil.

We will be using a 3D printed assembly for the wing joiner. It will be 100% inside the wing and not visible. We have found this method to be very robust and makes the build easier. It simply glues into the spar caps and has all angles already built in.

This sounds just great. I hope it comes into production.

 

[Shoelace]

Great thread. My very first glider was an Olympic 650 sometime around 1984(?). Easy to build/easy to fly.

 

[Sandman]

Is the mating surface of the trailing edge threaded hardwood blocks inside the fuselage, beveled to match the dihederal angle.
What about the leading edge dihederal gap, as the Prelude wing platform is flat.

Don