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Jul 06, 2017, 01:21 PM
Light flies right!
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Build Log

Mimi 1m DLG Build


About a month ago, I was looking for a simple to build, relatively cheap upgrade to a Gambler+ DLG that I acquired at a swap meet. While the Gambler is a decent flyer and will occasionally catch a passing thermal, my particular model is on the heavy side (7.5 oz) and I feel like I have reached a limit in its performance, especially in launch height. Since I have no other hands-on experience with DLGs, I figured that I may as well build another balsa DLG to see if I could get better performance.

The Mimi was the perfect model for my requirements, as it is a newer design that is known to launch well. And, since it has several wing construction methods there is a lot of potential for comparison and experimentation. As a 1-meter DLG, it's also slightly more portable than the Gambler, although in reality I'll probably be flying both when the conditions are good. With all this in mind, I went ahead and got the free plans from the designer, Frans Bal. Frans, thank you so much for your generosity in making the plans available! I know that DLG pilots all around the world appreciate your excellent design!

After ordering my materials and printing the built-up and semi-solid versions of the plans, I decided to start work on the semi-solid version of the Mimi. This is because the 1/2" balsa I ordered from SIG is on the heavier side (around 8 lb/cu ft), so I am anticipating that this wing will end up heavier than the built-up one and will thereby provide a good baseline for performance. I also haven't worked with balsa in a while, so the simpler construction should help me regain my woodworking skills.

So far I've only got a few small parts cut out since I'm waiting on a few more parts, but I feel pretty good about what I have so far. Here's a list of the weights for each component, according to my triple beam balance:

1/2" balsa wing LE blocks (4), roughly cut: 65.6 grams
3/32" contest balsa vertical stab, unsanded: 3.2 grams
3/32" contest balsa horizontal stab, unsanded: 3.1 grams
P1X tail boom, cut to 500mm length: 7.8 grams
Uni carbon launch peg, shaped: 0.9 grams
Wing plywood pieces: 2.0 grams

I'm guessing that the AUW for the semi-solid configuration will be around 170 to 180 grams, so it probably won't be a lightweight. I think this wing will excel on days with more wind, while the built-up wing will be suited for calm conditions. Stay tuned for more progress!
Last edited by Aer0naught; Oct 28, 2017 at 09:26 PM. Reason: Added photo
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Jul 06, 2017, 06:56 PM
First joined Sep 2001
quote" I'm guessing that the AUW for the semi-solid configuration will be around 170 to 180 grams, so it probably won't be a lightweight. I think this wing will excel on days with more wind, while the built-up wing will be suited for calm conditions. Stay tuned for more progress!" end quote

With ballast the built up version will also handle wind.

https://www.rcgroups.com/forums/show...3&postcount=13

cheers
Bm
Oct 28, 2017, 09:24 PM
Light flies right!
Thread OP
Quote:
Originally Posted by BlRDMAN
With ballast the built up version will also handle wind.

https://www.rcgroups.com/forums/show...3&postcount=13

cheers
Bm
I wouldn't doubt it! Your built-up MiMi is what I'm hoping mine imitates! I'm just looking at comparing the different wing types to see whether there are any major differences in handling, e.g. between polyhedral and dihedral.

To that end, I now have enough light (5 lb/cu. ft) balsa to also build the solid balsa wing. I still haven't made much progress on the build due to other commitments, although I do have a couple more small parts shaped since I lasted updated. At this pace I'll probably be done in ten years or so!
Jan 23, 2018, 09:33 PM
Light flies right!
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A Large(r) Diversion...


So I haven't been working on the MiMi at all in the past months, but I do have a small (well, technically larger, in terms of physical size compared to the MiMi ), similar DLG project that I've just recently finished up: a complete fuselage rebuild for my Gambler+. Figured it would be a good practice project to get reacquainted with balsa, and I think it really turned out nice! The old fuse had a number of repairs from previous owners, which made it excessively heavy. Old AUW was over 7.5 oz/215 grams, which is on the hefty side, but with the new light tail feathers (no glass, pull-spring, and a minimum of CF tow reinforcement), I've managed to cut 25% off of this, giving a new AUW of just 5.8 oz/164 grams! Needless to say, the weight loss program has made a true floater out of this old plane! I definitely have a much easier time sensing lift now, although the cruise speed is a bit lower and it's obviously a lot less wind-tolerant. I do worry about the tails exploding on launch or warping from the torsion springs , but so far they seem to be holding up just fine.

Photos below have more details!
Jun 12, 2018, 05:39 PM
Light flies right!
Thread OP

One Year Later... Progress!


Finally got around to doing some more work on the MiMi, after a year of busy-ness. I'm currently working on the solid wing; I figured that I should start with it since the MiMi build log album is very well documented for this wing type. I'll come back to the semi-solid wing for comparison, and I will eventually get around to the built-up dihedral wing. I may even end up making some changes to the original wing design for a polyhedral built-up wing. That being said, I have enough supplies for at least 3 complete MiMis, so the extra airframes will be going to friends

So far I have the 1/2" balsa blocks glued up with Ambroid. I'm not sure if this is the best glue to use for this application, since there is a bit of give when I try to flex the panels chordwise, but maybe after drying more it will solidify. I did try to sand the block edges as accurately as I could for a tight fit, and I made sure to coat the edges before gluing. The build photo log by Frans seems to show the use of some type of CA for this purpose, but I was thinking CA would be more difficult to sand later on when compared to Ambroid. If my wing explodes on launch, I'll know what I did wrong!

At this point, all four unshaped panels together weigh 156 grams, which is right around the target weight for the completed plane. Considering that more than half of this wood is going to be removed, I think this is right on the money in terms of weight!


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