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May 23, 2018, 12:33 PM
a quantum of science
Alex Guffler's Avatar
Thread OP

Updates May

Hi everybody,

We finished all molds to 5000 grain, polished and waxed them. This was very time consuming! Now we are ready for building the production molds.
There were preperations for wing core milling. First wing cores are expected to be milled in June.
Also, we demolded the first production mold of the fin mold with included flap spars. The first fin looks really nice and its weight is again around 5g, but we need some core thickness offset adjustment for the next fins. So far, the production molds from carbon fiber with directly molded rib work absolutely flawless.

As most of the team members are students, they need to take some time for studying too, which slowed the project down a little bit and I was on a business trip to China, but we make constant progress. We are looking forward to having the first full airplane as soon as possible, but we prefer quality work and we will take our time. So please stay tuned and I promise to post news again more frequently!
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May 31, 2018, 03:16 PM
Registered User
Miderror's Avatar
Looking good Alex,
And thanks for letting Dan and I stop by the lab while we were in Germany last April.
It was a treat and the bier was extra good as well!
Oct 13, 2018, 08:00 AM
a quantum of science
Alex Guffler's Avatar
Thread OP

Update October 2018

Hi everybody!
exams for our students and lots of flying in summer steal some time for the project, but there was great progress since my last post!

First, all production molds are finished! So very soon, we will have the first complete Ascender model in our hands.
Second, we had a large upgrade in our manufacturing gear and we got a side channel compressor. With this tool, we can ensure an optimal quality of core milling process, without torturing our vacuum cleaners any more.
We also built the very first fuselage. As you can tell from the pictures, some edges will need more rovings, but it's only a matter of experience and training. Including aluminum/steel inserts for screws, the fuselage is at 32g weight. The hexagon ending gives a nice snug fit and the fin is alligned perfectly!

I believe we will have the first full Ascender by end of this year. Coming next: The first set of wings!
Dec 16, 2018, 05:10 PM
a quantum of science
Alex Guffler's Avatar
Thread OP

Maiden Flight Video!

Hi everybody!

No big words today, here it is!

AkaModell Munich Ascender maiden flight (0 min 16 sec)

In the next days, we will work out a full flight video and prepare more information for you about our first prototype.
We are really happy about our maiden flight today. It was snowy and we had some icing on the wings, but the Ascender looked really promising in flight!
Dec 16, 2018, 05:25 PM
ThomasLee's Avatar
Very cool, and congratulations on a pretty plane and successful maiden!
Dec 18, 2018, 05:04 PM
a quantum of science
Alex Guffler's Avatar
Thread OP

First flights, more information

Today, I had the great pleasure to fly our Ascender Prototype for two hours on my own. I made about 80 launches and the aim was to set up all flight modes, trims and mixers. The weather in southern Germany was very nice today, a lot better than at the maiden last Sunday.

First, I want to give more information about the #1 prototype:

General: For our first plane, we chose a conservative layup. Strong and easy to build, without saving too much resin for getting a nice surface finish. And we wanted to avoid delamination at demolding, so we painted all parts with IMC laqueur.

1) Fuselage
- Thin clear paint film (IMC in-mold).
- Layup: Outer layer 60 g/sqm Aspro Spread tow 0/90 deg. Then 100 g/sqm HM-UD. Inner layer again 60 g/sqm Aspro Spread Tow but +-45 deg. The nose area is three layers 163 g/sqm black stained glass fiber. Small 90 g/sqm patches and UD patches for the elevator pylon. Some 12k rovings in edges.
- Steel nuts M3 for the wing, aluminum nuts M3 in the pylon.
- Fuselage weight: 34g

2) Tails
- Thin clear paint film (IMC in-mold).
- Layup: Outer layer 16 g/sqm GRM Carboweave. Spar A-spread tape 30 g/sqm. Leading edge GRM Carboweave 20 g/sqm on 3M transfer tape . Patches from 20 g/sqm GRM carboweave. Kevlar hinge from pre-laminated 65 g/sqm fabric. 6k rovings in the leading edge. Trailing edge black microballons resin. Carbon sleeve for the hexagonal insert of the fin.
- Fin weight: 7 g
- Elevator weight: 6.5 g
Yes, the tails came out a little heavy. We will improve!

3) The joiner is built seperately from carbon sleeve and rovings (24k M40J). The Rohacell core is machined by CNC.

4) Wing
- Thin clear paint film (IMC in-mold). Decals with orange and white IMC.
- Layup: Outer layer 62 g/sqm Textreme IMS. Also some reinforcements same material. Spar caps from overall 18k to 6k M40J rovings. Joiner pocket Kevlar sleeve. Leading edge 40 g/sqm GRM Carboweave on 3M transfer tape. Flap spars also from 40 g/sqm Carboweave. Some 3k rovings for edges.
- Wing weight (including joiner, peg, aileron horns) 131 g
We did without wing spar to reduce complexity of the building process and to avoid optical footprint of the spar. Maybe, we will try the next wing featuring a spar and UD tape for the spar caps.

5) Servo installation
- The servo mount is 3d printed. It weighs about 6g. It holds 4x KST X08 Servos and there is some space for a 10 mm brass bar as ballast. The servo mount is then screwed into the fuselage, it is just fixed from below and the screws run through the fuselage wall. Quite pragmatic, but really practical, because the servo mount still needs some improvements.
- I will make an extra post on the servo installation soon. Once we have the final servo mount ;-)

6) Other components: We wanted to use a 1s 600 mAh battery, but for the first flights I used 2s 350 mAh Lipos. My reciever is an 8 channel with integrated vario.

Due to the slightly heavy tails, we needed about 12g lead to balance the plane. Now, its AUW is 269 g. Not perfect yet, but we did not try to save resin. With some slight changes we should not need much lead for balance and also less than 250 g AUW appears realistic.

Nevertheless, the 269g prototype flies really nice. All doubts, wether the thin airfoil choice would produce delicate flight behavior could not be confirmed so far. But it's true, the Ascender is not the floater kind of plane, it flies really fast when you set the speed flightmode. Another indicator for Ascender's high speed quality are the launch altitudes. I can't tell launch altitudes right now, because I am a really bad launcher. But I cracked my personal launch record so far with the Ascender today with ease! Some other guys in the team do a lot better. And we will meet up some F3K contest pilots soon and then we will see! Rudder works like a charm on this plane, it is so sensitive to slight control inputs.

In January, we will build the next prototype of the Ascender with slight improvements. We are open to your comments and recommondations. We believe, there is still a lot of potential. And thank you everybody for the positive feedback so far!

If somebody wants to meet us and the plane, we can get into touch!
Dec 19, 2018, 07:41 AM
Father of Fr3aK, DLG Pilot
tom43004's Avatar
Very nice work. I've been lurking the thread for a while waiting to see the results. Looks like it's all coming together as expected.
Dec 22, 2018, 11:31 AM
a quantum of science
Alex Guffler's Avatar
Thread OP

More Ascender stuff!

Hi everybody!

Today, I have three new things for you:

1) Another Ascender flight video:

Ascender Christmas Video (1 min 42 sec)

We are still working on a nice full flight video, so stay tuned.

2) A data sheet of the airplane. Somehow, it is a must-have.

3) Some detail photos of the unique Ascender wing root area. The joiner is glued in the left wing at molds closing. I attached also some pics of the aileron connection to the servos in the fuselage and detail photos of the tails.
Dec 25, 2018, 06:03 PM
a quantum of science
Alex Guffler's Avatar
Thread OP
I went out today for a Christmas session with the Ascender!

Ascender F3K X-mas flying (6 min 55 sec)

I did also some slope soaring behind the trees, but the video just features some aerobatic scenes.
I get more and more excited about this plane!
Dec 30, 2018, 05:08 AM
a quantum of science
Alex Guffler's Avatar
Thread OP

Ascender Prototype #2

Yesterday, we had a marathon-like 12 hour building session. We painted, prepared all fabric and laminated all parts of prototype #2. The day before, we CNC-milled all Rohacell cores and laminated a spar joiner.

Prototype #2 features:
  • tails: 16 g/sqm Carboweave (GRM)
  • fuselage: 62 g/sqm Aspro A-60 IMS 0/90°, 100 g/sqm HM-UD, 62 g/sqm A-Spread IMS
  • wing: 40 g/sqm Carboweave (Vladimir's model) for the wing and 62 g/sqm A-Spread for the ailerons. There is a C-type spar now in the wing core. Spar caps are made out of stripes 100 g/sqm HM-UD. Some reinforcement patches 62 g/sqm A-Spread.

With this layup, we hope to get a stiffer but lighter wing. As the airfoil is quite thin, ailerons are still in strong layup.
Hardening and tempering takes some days, we are looking forward to the results.

We used a lot of sponsored material for this plane again! Thanks to GRM, Vladimir Gavrilko, Evonik, 3M and Asprotec!
We already got some purchasing inquiries for the Ascender. Very sorry, but selling the Ascender on a regular basis is not planned and intended. It is so much work to build one! This project is still hobby for us (sometimes very demanding). But a sucessor like an "Ascender 2" might be possible in case Ascender (1) gets positive feedback by contest pilots and some other factors come together. First, let's have some fun with the current non-commercial project!

Again, thanks for your comments here and the german thread on rc-network and facebook groups. We appreciate the F3K-community a lot! I'm sure, it will be possible to see the Ascender live one some contests in Germany in 2019.
Jan 14, 2019, 02:18 PM
Registered User

Prototype #2 is out of the molds!

Prototype #2 is out of the molds, sadly not everything went as expected.

The components easily came out of the molds, however, the fuselage is not completely closed in two places, as the foil bag, which we currently use as a balloon replacement, did not expand properly at the end of the fuselage.

The wing is a bit lighter compared to # 1, unfortunately the spar delaminated during a first load test near the wingtip. Since the wing is thus unusable, we further dissected the wing and pulled some valuable findings from it. The reason for the delamination was the use of UD-tape instead of rovings like we did with # 1. While the rovings were narrower and a little thicker and thus provide sufficient buckling resistance, the UD-tape spar cap failed due to buckle. Unfortunately, the spar web we tried with # 2 could not help either.

Quite unspectacular are both tails, which came out nice and shiny as usual. We could also save some weight and further optimize the building process.

Although this attempt was somewhat disappointing overall, we have gained important experience and are already working on building # 3 with the necessary improvements.

Some more details on component weights and a few pictures.
  • Horizontal Tail: 6,13g without trimming
  • Vertical Tail: 6,98g without trimming
  • Fuselage: 38,04g without trimming
  • Wing half without joiner: 50,72g without trimming
  • Wing half with joiner: 57,77g without trimming
Feb 25, 2019, 03:29 PM
a quantum of science
Alex Guffler's Avatar
Thread OP

Progress in the Ascender project

Hi everybody,

due to exams, we had to slow down a bit. But we had a lot going on since the last post. Currently, we are building the first mini series of Ascender airplanes. I can't count right now, but it must be about 7 built fuselages, 5 sets of tails and two more pairs of wings.

We are optimizing layups and stiffness and solve some minor and major problems. For example, the fuselage needed some reinforcements near the aileron horn opening. But at the same time, use of carboweave gave us 32g fuselage weight! And the fuselage appears really stiff and solid.
Same for tails, experience and some little experiments now produce an 11g set of tails.
We also improved stiffness of the wing. As you might remember, the wing is really thin, and so it's a little challenging. Wing set #2 broke at light load tests because of buckling and delamination. A carbon sleeve was the solution: double spar and better prevention of buckling. Now, we are pleased with stiffness and weight by wings #3 and #4.

Unfortunately, there was also some bad luck. Our #1 prototype had a crash, when the fuselage broke during a hard launch (the reason for the new reinforcement...). As we have some spare fuselages, #1 will be airbourne by next weekend again I think. Also, wings #3 and #4 had issues with the joiner integration. This led to #4 (the red one with carboweave) to end up as a non-seperable wing. The #4 wing with carboweave is at 105 g by the way. Our solution is to make a new joiner mold with changed offset for the spar cap UD. The joiner will also be shorter. Maybe we will be able to manufacture a steel master joiner for making the pocket in the right hand wing side. But our metal CNC machine still needs some major overhaul.

Finally, we had a really nice visit by Walther, who is very active in the German rc-network. He owns almost every currently available top model in the F3K league. And he has flown them all. Unfortunately, weather was really bad when he was here, so we had to postpone the flying. But I'm sure in March we will find a date to go flying. We are looking forward to his expert evaluation of the Ascender soon!

By the way, the German folks will be able to meet us and the Ascender in Babenhausen on 30th of March at the F3K workshop!
Last edited by Alex Guffler; Feb 25, 2019 at 05:06 PM.
Feb 25, 2019, 04:00 PM
Registered User
Rollo340's Avatar
Looking very much forward to meeting you guys and the Ascender for the first time, Alex
Apr 22, 2019, 05:59 AM
a quantum of science
Alex Guffler's Avatar
Thread OP

First competition participation


We have built some more Ascender planes and we visited some events in Germany.
We have been to the F3K Workshop in Babenhausen, where we met Rollo and a lot of other great guys.

In Etsdorf, we took part in a regular D-Tour contest. As we are not pro pilots, we can not compete the establishment directly.
But the Ascender seems to be able to do quite well in better pilot's hands. We invited some guys to fly the Ascender. They said it was rather sensitive and flying faster than what they are used to. We are still about getting to know the plane better. CG, mixers, settings... There is a lot to be tuned. Anyhow, it needs careful and precise flying. It is not very forgiving.

The contest scenario also revealed some weak points of the construction. In the next builds, we will improve at those points.
We will definitely take part in the contests in Bavaria this summer. See you around!

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