Aeroic Gremlin, build (Aeroic donation to the 2019 ISR)

[Konrad]

The Northern California Slope Soaring (NCSS) International Slope Race (ISR) for 2019 is in the history books. This is a great open Man on Man (MoM) racing format.
A big draw for me was that the NCSS awards prizes to the workers not the pilots. The pilots get trophies and bragging right. But it is the workers that get all the donated loot! This isn’t a tube of glue kind of prize, but real desirable prizes. For example James Hammond donated an Aeroic Gremlin.

I was lucky to be assigned the first draw. I chose the Aeroic Gremlin. I have to admit this isn’t my style of plane. But, I hope to give it a try!

Aeroic Gremlin

Objective:I wanted to make a small, high performance addition to the Aeroic range, but with ease of transport and affordability in mind, plus extreme flexibility of build type and so the BIBOC concept was born.“BIBOC”“BIBOC is a new acronym that means “Bu

alofthobbies.com

I’ll try to do my usual detailed build here in this thread. I recall Mo doing one here on Aloft's forum, so I’m off the gain insight from others.

All the best,
Konrad

 

[Wayne]

They are a good plane and a lot of fun. Yeah, they don't thermal well at all.. LOL

Mo has another one he will be building up for me as a customer talked me out of the first one he built up.

 

[Konrad]

What? I thought these were LAR thermal ship?
LAR; Low Aspect Ratio wings

In the sales write up I read something about full flying stabs as an option. I don't see how, as the stab binds on the rudder push rod fairing. Has anybody installed the 180° elevator on these Gremlins?

The more I look at this and hold her the more I'm liking the model. In a couple of days I might actually be excited to build her.

 

[Konrad]

Looking at the rudder I'm noticing some geometry issue with the side (offset) live hinge when wanting to move the rudder, say more than 15°. I'm thinking of changing the rudder hinge to a center line hidden style, like I did on the Mibo Dart III.

60" Molded racers for MoM

Got out in the afternoon and test flew at Mussel Rock an ancient 60" moldie called the "Flash II", sold by North East Sailplanes 20 years ago. Ran into a fellow sloper who goes by the handle funkyfreestyler. He was helping me read the slope. I think out of frustration with me not following his...

forum.alofthobbies.com

 

[Wayne]

No, I don't know of anyone that has done a mad stab to this plane, and I rather hope you do not. They tend to cause more issues, and are a lot higher maintenance.

Rudder - You can, but she flies good as she is.

 

[Konrad]

"MAD STAB". The nomenclature might be giving someone a clue.

From a maintenance perspective I see cable stretch as the main issue. Is there something else that becomes an issue?

As delivered I can't get more than 15° of rudder. Wiper binds on bottom of vertical fin's spar. If sanding clearance there is no wiper left. Yes, the wiper is the greatest distance away from the spar in neutral but it also moves the greatest distance when making a left hand turn. Bottom of this spar should be moved forward so that it is slated the same amount as the inclusive angle of the vertical fin sides (if staying with a side hinge).

 

[Wayne]

Mad Stab - depends on how the unit is designed.. Seen many. Some last 1 flight, some last 50. All seem to have issues at some point and crash the plane.

 

[Konrad]

Mad Stab - depends on how the unit is designed.. Seen many. Some last 1 flight, some last 50. All seem to have issues at some point and crash the plane.

That sounds like a challenge! Now I'm sure I don't want to use a $500 ship to prototype control systems. I think Topmodel might have a lower cost but much more flexible (soft) glider for a lot less.

At the price point of the Gremlin I'm looking for proven set ups. I know I didn't pay for it in the classic sense. But still baking in the hot sun (ok, it was a cool ocean breeze) does has a cost associated with it.

 

[Wayne]

Build it stock, you will love it.. I think.

 

[Konrad]

LOL,
STOCK, what's that?

 

[Johnnashville]

Mad stabs are fun on super light weight planes. The recovery time and altitude required on moldies is long, crash in the water crazy.
A stock Gremlin is capable of some wild up line tumbles . I feel a mad stab would only prevent exploring the airframes true potential

 

[Konrad]

Is the MAD setup any worse than the Classic Full Flying stab (AMT) if kept to the same amount of movement (25°+)?

 

[Konrad]

Like I said earlier, the more I look at her the more I like her.

I like all the carbon strips to stiffen the canopy. Far too often a large canopy will flex and come off durring knife edge flight.

I love the fish mouth load spreader and that is goes so far aft of the wing fairing! I also like that there are both kevlar for toughness and Carbon for stiffness in so much of the fuselage.

I’ve decided to use mini X10’s for the flaps and use IDS mono trays as I fear I’m likely to strip the gears at sometime in the Gremlin's life (more than once)! I’m going to use X0-8’s for the ailerons and elevator to keep the weight out of the extreme ends of the plane. And I’m going to use a DS215 on the rudder for its speed. As the XO-8’s aren’t known for their speed I think I’ll run the radio off of a 2 cell LiFe battery.

KST X10 Mini Wing Servo - 7.5Kg (104.16 oz in), .09sec - High Voltage

If the X10 is physically too big and the X08 is too low on torque the X10 mini might be just right. The X10 mini, like it's bigger brother the X10, sports an improved motor controller that's driving a coreless motor which in turn is spinning a minimal bac

alofthobbies.com

Servorahmen IDS Mono for KST 125,135, 225

The Integrated Drive System, aka IDS is the cutting edge method for mounting wing servos in high performance aircraft. The servo trays have an outboard ball bearing that helps to carry the servo shaft loads and greatly reduces servo play. This superior de

alofthobbies.com

KST X08H Servo - 2.8Kg (38.88 oz in), .09-sec - Wide Voltage

KST's new tiny alloy servo, the X08 is just 8mm wide and weighs just 8 grams, but it packs a real punch!

alofthobbies.com

KST DS215MG Servo - 3.70Kg (51.38 oz in), .05 sec - Wide Voltage

Blistering speed is the name of the game with this alloy cased digital coreless servo. With a 3.7kg.cm torque rating the KST DS115MG is appropriate for many high demand uses including high speed gliders, helicopters and sport planes.

alofthobbies.com

All the best,
Konrad

 

[Konrad]

I just got this note from the designer.

...
But remember its not meant for VTPR - flipping style flying.

Cheers,

Doc

Obviously I didn't understand what "Freestyle" meant!
Armed with this I'm going to set up my Gremlin with camber changing controls.

All the best,
Konrad

 

[Konrad]

Now that I know what the designer was thinking with the term “Freestyle". The Gremlin is not VTPR ship. That means that ballast might become a useful trimming tool. I’m thinking of placing the ballast in the wing joiner. With the Gremlin the wing joiner is a very nice mandrel wound thin walled carbon tube. Mine has an I.D. that is just too small for a 16mm rod. But a 5/8 O.D. (15.88mm) rod fit perfectly. I will be using K&S brass tube # 8143 as the carrier for my lead.

I’ll make a modification to the joiner as it is a thin wall tube. While I do want the tube to fail should I make a bad landing. I don’t want it to fail prematurely. So I’ll add a balsa core to the center of the tube to act as a filler that keeps the tube walls from collapsing. This balsa core will span the fuselage to wing joint. Then outboard of this will be the pockets in which I’ll place the ballast.

I’d like to ask those that have flown the Gremlin if their preferred Center of Gravity actually is on the center line of the wing joiner. If not it would mean that I should allow some area where I can add ballast trim as I ballast up the Gremlin. I hope the joiner is centered on the CofG.

All the best,
Konrad

P.S.
Can one get replacement joiners? I'm sure they aren't cheap. But I also don't want to pay for shipping 1 meter long tubes and then try to cut them to size. To my way of thinking the joiner is a mechanical fuse. (A designed failure point to save the wings and fuselage on impact). It would be nice to get these on demand. I'd like an OEM spec'd tube as this is a key feature of the model.

 

[Doc James Hammond]

Now that I know what the designer was thinking with the term “Freestyle". The Gremlin is not VTPR ship. That means that ballast might become a useful trimming tool. I’m thinking of placing the ballast in the wing joiner. With the Gremlin the wing joiner is a very nice mandrel wound thin walled carbon tube. Mine has an I.D. that is just too small for a 16mm rod. But a 5/8 O.D. (15.88mm) rod fit perfectly. I will be using K&S brass tube # 8143 as the carrier for my lead.

I’ll make a modification to the joiner as it is a thin wall tube. While I do want the tube to fail should I make a bad landing. I don’t want it to fail prematurely. So I’ll add a balsa core to the center of the tube to act as a filler that keeps the tube walls from collapsing. This balsa core will span the fuselage to wing joint. Then outboard of this will be the pockets in which I’ll place the ballast.

I’d like to ask those that have flown the Gremlin if their preferred Center of Gravity actually is on the center line of the wing joiner. If not it would mean that I should allow some area where I can add ballast trim as I ballast up the Gremlin. I hope the joiner is centered on the CofG.

All the best,
Konrad

P.S.
Can one get replacement joiners? I'm sure they aren't cheap. But I also don't want to pay for shipping 1 meter long tubes and then try to cut them to size. To my way of thinking the joiner is a mechanical fuse. (A designed failure point to save the wings and fuselage on impact). It would be nice to get these on demand. I'd like an OEM spec'd tube as this is a key feature of the model.

The idea was always to use the joiner as a ballast vehicle one way or another, Konrad.
This can either be by placing weight inside the joiner tube - or replacing it with aluminium etc.
Mo knows more about building this plane than most, he's local to you, and he's flown it too which helps.
As Wayne mentions I wouldn't worry too much about changing anything - it really does fly as it was designed to do as you have it. I think it will probably teach you quite a bit about slope aerobatics, while forgiving you too.

Cheers,

Doc.

 

[Konrad]

It has been decades since I last built anything, for the hobby, that matched the instructions or documentation! The only things I plan on changing are the rudder hinge and to drive the flaps with an IDS setup. Not that there is a problem with the rudder hinging. I Just like a center hinge. It will also give me practice at making epoxy wipers. And the IDS is because I'm really liking the servo tray and the solid push rods (no wire flex). I'm not using the IDS on the ailerons as I'm trying to save weight out at the tips (no servo trays).

I've been following Mo's build. I will give it a thorough read. I'll be looking for control set up and balance information.
(If anyone is following along, my builds are NOT product reviews. More often than not they are punctuated with what "I" think is best, not with what the designer had intended)

Aeroic Gremlin build

This is a prototype Gremlin, so some of the accessories have been copied from a production model to get it in the air, radio/fuse former, there is also a vertical former that I will need to make. When gluing formers in, I use thin CA to tack in place then use a syringe to apply 30minute epoxy...

forum.alofthobbies.com

Thanks for letting me know that the placement of the joiner was determined not only with structural criteria but also with balance concerns taken into account. One of the problems of being in the USA, other than our current political problem, is that metric spec'd materials are not readily available, I'll need to special order metric rods. I think our police won't know what I'm doing ordering magnesium, Aluminum, Brass, Stainless Steel, and Tungsten rods. Really NAS officer these are for my drone. What a horrible term as it congers up images of an autonomies killing machine! Please refer back to our political problem with Amazon and DJI wanting our airspace!

By your last statement I see you have been watching me try to fly.

All the best,
Konrad

 

[Doc James Hammond]

It has been decades since I last built anything, for the hobby, that matched the instructions of documentation. The only things I plan on changing are the rudder hinge and to drive the flaps with an IDS setup.
Not that there is a problem with the rudder hinging. I Just like a center hinge. It will also give me practice at making epoxy wippers. And the IDS is because I'm really liking the servo tray and the solid puch rods (no wire flex). I'm not using the IDS on the ailerons as I'm trying to save weight out at the tips (no servo trays).

I've been following Mo's build. I will give it a thorough read. I'll be looking for control set up and balance information.

Thanks for letting me know that the placement of the joiner was determained not only with structural criteria inming but also with balance concerns taken into account. One of the problems of being in the USA, other than our current political problem, is that metric spec'd materials are not readily available, I'll need to special order metric rods. I think our police won't know what I'm doing ordering magnizium, Aluminum, Brass, Stainless Steel, and Tungsten rods. Really NAS officer these are for my drone. What a horrable term as it congers up imagaes of an otonimis killing machine! Please refer back to our political problem with Amazon and DJI wanting our airspace!

"congers up imagaes of an otonimis killing machine"

Konrad - your spelling is the image of an autonomous killing machine! You did this on purpose I'm convinced. You have to be very good to be that bad - I'm still tickled.

Seriously though, an aluminium rod will be quite enough ballast without the Tungsten, Strontium 90, active Uranium, etc ones on your list though you might make a brass or stainless example if you want to turn the model into a BTTW screaming banshee 60" racer.

And...If I remember correctly, I purposely made the carbon joiner tube 16mm - that's 0.629" - so any USA available 3/4" rod at 0.625" will fit just fine if you can accept the 004" of potential slop.
And to make your build even simpler, I wouldn't worry too much about saving weight out at the tips. The section is 10% thick, and the tips are very close to each other at this aspect ratio, so I'm sure IDS would work fine - especially with the echoing cavern you have to work with inside the wings. You could get lost in there.

Very best,

Doc.

 

[Konrad]

LOL, and sorry about that!

Yes, my writing "IS" that bad!! Even more so when I haven't had my first cup of tea. (In my work I was never allowed to write legally binding contracts!)

BTW: "conjures up images of autonomous killing machines", Not killer eels but that fits.

A coat of paint should take up that .1mm of slop.

Yes, those XO-8's are lost in the aileron servo pockets.

All the best,
Konrad

 

[Doc James Hammond]

Priceless...