Mountain Models "Lucky ACE"--RELEASED - RC Groups
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Aug 10, 2008, 07:21 PM
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buzzltyr's Avatar

Mountain Models "Lucky ACE"--RELEASED

Brian Eberwein, "Mr. Mountain Models", has been dropping hints for awhile now about his "secret" project, in the "Learning to Build: Mountain Model's Dandy" thread and his Super Cub/L4 thread. The Dandy thread is particularly appropriate, as the "secret" project is a new model, not unlike the Dandy GT.
It is a "stick" type model, with a fully symmetrical wing (Brian told me it is a 12% airfoil), full length ailerons, and decent sized control surfaces. However construction methods and design more closely mirror the EZ series than the Dandy, at least in terms of the fuselage. There is also a modest surprise regarding the fuselage and the landing gear.

Brian has flown his prototype, and reports that it is quite aerobatic, and still slows down nicely for landing. Basic specs are a 40" wingspan, a 29" long fuselage, and a 16-17 oz AUW. Brian will have to weigh in with square area of the wing, etc., as I've forgotten to ask what they are.

Once again, I consider myself to be very fortunate to be entrusted with another MM beta build. It is always a treat to tackle a brand new design.
Thanks, Brian, for the opportunity and the trust!

The first pic is of the wood from the kit. I forgot to put the hardware package in the picture, but it includes all the bolts, blind nuts, wheels, etc. that you would expect in a MM kit. The wood seems very nice, lightweight, and straight.

The second picture is of Brian's recommended "absolutely insane, 'way too much power for a plane this size and weight" power system. It's a Scorpion 2215-18, and the matching 25amp Scorpion ESC. Prop will be a 10x5 APC E prop. Seros will be Hitec 55's. Based on Scorpion's numbers and a 1000-1500 mAh battery, we should be close to 200 watts, or around 200 watts per pound. Unlimited vertical seems to be a given.

Brian is still tweaking the design in spots, so the production kits may vary a bit from my beta kit. Brian is also still working on the instructions, but he did provide me some CAD-based jpeg's which allowed me to identify parts and generally figure out what-goes-where.

So again, my thanks to Brian for the opportunity to build the Lucky ACE.

And for those who are curious about the name, ACE happens to be the initials of Brian's two year old son. So Brian, ever the doting Dad, has immortalized his son in the spirit and structure of this model.

Last edited by buzzltyr; Sep 25, 2008 at 11:44 AM.
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Aug 10, 2008, 07:28 PM
Obviously I'm a "Minus Member"
buzzltyr's Avatar


I decided to start with the tailfeathers as a warmup for the build. As I would have expected, most of the time in building them was spent removing them from the carrier sheets.

I think total build time for them was somewhere in the 15-20 minute range.
The outlines are all dovetailed joints, with appropriate cross pieces. Parts fit was great, with no issues whatsoever. Weight of the completed tail parts came in at .37 ounces.

The build and this thread will progress as available time permits. We have a bunch of people on vacation where I work, so my hours for building will be limited for awhile. But I will forge ahead whenever I can! I am anxious to get her built and into the air.

Aug 10, 2008, 08:45 PM
God is my pilot
JimTMich's Avatar
Thanks Mark for the build thread! I'm looking forward to seeing what the super secret plane is!
Aug 10, 2008, 09:04 PM
BYOP - Build Your Own Planes
Mountain Models's Avatar
Here's a finished model shot of the "Lucky ACE"

As mark said, it's named for my son, Aidan Charles Eberwein... I just had to do something with initials like that.

In talking with one of my dealers, Doug, and a couple other guys, I decided to update the Dandy GT. It took on a life of its own and ended up where you see it. I had put it on hold last year, but recently decided to build it, just for myself, as a fun non-work related project. Well, as these things happen, it came back as a full project again.

For flying characteristics, itís not a pattern plane, but on lower rates, it flies very crisp, goes where you point it, and responsive. Even with a 12% airfoil, it slows way down with the light wing loading. For 3D maneuvers, Iím still playing with it, but it seems to do most maneuvers. Knife edge, obviously, isnít going to be great because of the small side area, but itíll do just about anything else.

Doug was in Colorado Springs very briefly and I took him out to fly it, in the drizzling rain. When he gets home, Iíll let him tell you exactly what he thinks. To sum it up though, he loved it.

It has 2 landing gear mounts so you can change between tail-dragger and trike options.
With both mounts, I can see setting up floats with no modifications to the airframe at all.

Wing Span: 40 In.
Wing Area: 344 Sq. In.
Length: 32.4 In. (From firewall to back of rudder)
Weight: 16 to 17 Oz.
Airfoil: 12% Symmetrical
Last edited by Mountain Models; Aug 10, 2008 at 09:07 PM. Reason: I just can't be a tease...
Aug 10, 2008, 09:36 PM
M0unt@in M0del$ minion
turbojoe's Avatar
Yet another winner! Remember Brian, you promised me one of the first production kits.

Aug 10, 2008, 10:01 PM
Obviously I'm a "Minus Member"
buzzltyr's Avatar
Jim, it's not a "secret project" any more!

Brian, thanks for filling in the specs I never thought to ask you about. And for spilling the beans on the dual landing gear setup.

Joe, you'll just have to keep harassing Brian until he finishes up his tweaks, gets the instructions polished off, and gets one off in the mail to you.

Aug 10, 2008, 10:02 PM
It's a BIG park
PrkFlyrRic's Avatar
Hmmm, vertical fin is kinda small, but I like it.
40" and only 17 oz. I like that a lot.
I can see a center float with outboard pontoons...

Subscribed and watching with interest.

Aug 11, 2008, 12:58 AM
Registered User
BEC's Avatar
Ah......interesting indeed.

I like the dual landing gear choice as I prefer taildraggers and I like to provision for floats. I also like the sub-spars between the LE and the main spar - much better for keeping the airfoil shape with widely spaced ribs (one of the little things on the Dandy/Switchback wings I've always wanted to see addressed).

Will there be a Clark Y or NACA 2412 wing with a bit of dihedral (AKA a Sport wing) as well - or just the symmetrical wing?

Yes, interesting indeed.
Aug 11, 2008, 07:12 AM
Obviously I'm a "Minus Member"
buzzltyr's Avatar
BEC, Brian would have to address the issue of a different wing, but in looking at the fuselage sides, I'm not sure it would be easy to do. The LE of the wing fits a cutout in the fuselage sides, so some changes would have to be made to allow for dihedral. Not unlike the spacers that need to be inserted when going from a Dandy Sport to a Dandy GT to support the symmetrical wing. I'm sure that Brian could do it, but it would require some alterations to the fuselage side. On the other hand, I suppose he could do a sort of gull wing, with a center section to match the symmetrical wing and the fuselage, and then a different airfoil with some dihedral, outboard of the fuselage sides.
Maybe even have wing panels that plug into a center section? Only time (and Brian's creativity) will tell....

Aug 11, 2008, 10:07 AM
BYOP - Build Your Own Planes
Mountain Models's Avatar

I won't forget. Of course, I don't think you would let me forget either.


The vertical "looks" a bit small, but there's plenty. The vertical tail coeeficient is definitely good. Letting go of the sticks in a spin, it stops immediately.


I don't know about different wing sets yet. I dropped interchangable wings in the design process early on, but I could look at it again in the future.

The stringers definitely help the wing keep its shape much better than the Dandy/SB.

I will try to get some video this week. We got some with Doug, but the overcast + drizzling rain caused problems with focus... It was out of focus most of the time.

Aug 11, 2008, 10:16 AM
KSU Flyer's Avatar
A real nice looker...looks like a good second 4ch plane. ...that and I'm a sucker for trike gear.

Aug 11, 2008, 10:50 AM
Mountain Models Wannabe
CoClimber's Avatar
Real quick as I'm at work. I did get to fly the ACE and loved it. It felt very clean and stable, despite the windy conditions. The trike gear was fun and different. When I build one, I will want the trike setup.

Part of the reason the video I shot wasn't good was because Brian was really ripping up the sky. I couldn't keep up with him! When I flew it, I wanted to see the other end of the envelope and slowed it way down. It was almost in a harrier with just a bit of wing rock and no indication that it wanted to drop out into a spin. This characteristic made landing a snap. I brought it in with a touch of power and when it was just about to touch down I killed the power and it just set right down. Made me look better than my rusty thumbs really are.

This plane is definitely a winner.

Aug 11, 2008, 11:32 AM
Registered User
BEC's Avatar
Sounds like fun.


I saw that wing mount arrangement and realize that that makes a different airfoil on that fuselage difficult - more so than putting the symmetrical wing on the Dandy or SB with the little spacer bits. I was just curious what the "family plan" was - if any. There doesn't have to be one, after all.....

I'm all for a plane that makes me look better than I am .
Aug 11, 2008, 12:04 PM
Or current resident
glewis's Avatar
Hi guys. Brian has trusted me to join Mark as the other member of the beta build team. I hope to receive my kit tonight and will start working on it this week. I have a new 400XT motor laying around that needs a job so that is the proposed power system. With a GWS 9x5 prop on 3 cells it should be somewhere between sedate and the monster motor that Brian and Mark are using. For the rest of the stuff, a 4 channel Berg, HS-55ís, and a CC25 completes the control system. Iíll go with the trike gear and link to the rudder servo for ground steering. The plan now is to use a 2 or 3 cell 740 lipo for light weight general flying and when the wind comes up Iíll use a 1320 or 2200Mah for the added mass. With 344sq/in it should handle the weight (and wind) just fine. One thing I will do a bit different during construction is to use Titebond for the adhesive. I have started to develop a sensitivity to CA fumes and use it sparingly. I have used yellow glues on laser cut kits before and with the tight fitting joints it Ďgrabsí very quickly as the wood fibers swell.
Aug 11, 2008, 01:01 PM
Obviously I'm a "Minus Member"
buzzltyr's Avatar
Originally Posted by BEC

I'm all for a plane that makes me look better than I am .
Amen, BEC, Amen!


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