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The first German level 3 certification

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thomas

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I have the plan to be the first one to certify TRA L3 in Germany .
We have several L3 flyers but afaik they all did their certification flights in Switzerland.
Now that we have a TAP in Germany, it will be possible to certify here although we have some strickt bounding conditions.

The most important one is, that the rocket start weight must be below 25 kg (55 lbs), above that you need to get a license like for an real airplane.
We get only waivers up to 2.5km (8200 feet). The fields are also pretty small so that dual deployment is mandatory for anything above 1000 meter (3200 feet). And flights above mach speed are also prohibited.

So the rocket will be heavy to fly low and slow.

The basic design is a extended Formula 150 from rocketry warehouse 3.3m (10 feet) long, I might shorten this if there is enough space for the parachutes.
overview2.jpg


All rings of the fincan and beams are made out off 4 mm Birk Plywood with 8 layers unless otherwise mentioned.
The 2 cm width beams along the flight axis hold the fins.
They have cutouts over half their width for the centering rings which have according cutouts. Therefore beside holding the fins they also stabilize the centering rings along the flight axis and determine their spacing.
Here are some of the centering rings and the beams stabilizing the fins:
fincan_3k.jpg

The fins have cutouts for the centering rings up to 1 cm below the bodytube.
The centering rings have according 1 cm cutouts. As the beam the fins therefore act as stringers stabilizing the centering rings.

The first and last ring are made out of 6 mm Birk plywood with 12 layers with 3 mm groves for the fins from the motortube to the bodytube. They align the fins more precise than the beams can do.
Together with the centering rings this also prevents any canting of the fins along the flight axis.

The wooden beams will be laminated with strips of glass fiber cloth and epoxy to the motortube. All other parts are glued together with epoxy.
finca2_k.jpgfincan-1_k.jpg

The second last ring is only 3 mm thick but has a 1 mm G10 enforcement. It has 4 holes for M4 threaded rods which prolongate through the last centerring ring and are used to connect the thrustplate.
To strengthen the whole fincan it will be filled with 2k PU foam, the centering rings have holes to allow foam to expand through them.

The thrustplate consits of 6 mm G10 with a 2.5 mm deep groove on its outer edge so that it can be plugged inside the bodytube. It is not glued in but hold in place by 4 M4 nuts, which are connected with threaded rods to the second last centering ring. The thrustplate has a 2.5 mm deep cutout for the motortube. It also holds the 75 mm flanged Aeropack retainer which is held in place by 12 M4 screws connected through the thrustplate to KFS2-M4 PEM self clinching nuts. The holes for the M4 screws normally 4.2 mm in diameter have 2.5 mm deep enlargements to 6.4 mm to press-fit the KFS2-M4 PEM nuts. The nuts are pressed in place by a vise, while a installed screw is used for alignment.
thrustring1.jpgthrustring2.jpgthrustring3.jpg

The nosecone is unchanged from the rocketry warehouse formula 150 kit.
It consist of filament wound fiberglass with an Aluminum tip and has a Von Karman shape. The nosecone itself is 864 mm long an weights 2025 g. It is connected to the rocket by a 235 mm long coupler tube from which 150 mm protrude into the main body tube. A second ebay carrying a separate tracker for the nosecone is installed in the coupler. The ebay consist of two 3 mm thick G10 rings, which have 1 mm (closer to front) and 1.5 mm grooves aligning them in the coupler. They are connected by 4 M6 threaded steel rods. The ring closer to the front is open to allow the antenna of the tracker to protrude into the nosecone. The bulkhead closing the coupler tube has a M8 U-bolt for attachment of the drogue recovery gear. The electronic bay is 1 mm thick G10 which is connected to the M6 rods trough 15x15x2 mm aluminum angles. The tracker is an Altusmetrum TeleGPS which is hold in place by 4 M3 nylon screws. It is powered by a 1000 mAh 1s Lipo secured with tire warps to the sled. An Altimax MagSwitch is used for switching. The Antenna of the TeleGPS is aligned by a Plexiglas tube. The coupler is glued into the nosecone together with the upper bulkhead. It is further secured by six 3\,mm bolts.
tracker1.jpgtracker2.jpg
 

mpitfield

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First off good luck with your L3, you must be both excited and proud to be the first L3 to certify on your soil.

Regarding your choices and the build, it looks like you have already put quite a bit of thought into your choices and are off to a great start. What are you planning on doing for your AV bay, deployment technique, etc.? Have you worked out your flight profile? The CNC work looks familiar...Nat?

I will be following your progress.
 

Zeus-cat

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Good luck sir. I know you are still designing and building the rocket, but do you have a date in mind for the launch?
 

thomas

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I will only have a single point of separation and the main will be hold back by 2 spacetec SRM2 servo releases for redundancy.
Electronics will be a Telemega and an Altimax G3.
The lower coupler will be glued in the booster tube, and the AV bay will be placed in it secured by threaded rods.
It should fly on an M1297 if I can get one, to 1600m-1800m. A 4ft rocketman drogue will be deployed at apogee and Skyanlge CERT 3XL at 350m with the freebag method where the nosecone is recovered separately.
I made the CNC stuff myself.

Launch date will be 26th of May 2017 or August 2017.
We only have two large launches in Germany per year.
 

Spicer007

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Subscribed and best of luck on your L3 certification...
 

dhbarr

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Looks great, extremely strong! What motor for 25kg all-up weight -and- keeping it below 90% of 2.5km?
 

Bat-mite

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Thomas, I have no doubt you will go into the history books as the first to get L3 on German soil. Too bad nobody but us rocket geeks read those books! :) Best of luck!
 

EeebeeE

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Very well thought out. Once you certify there, bring it across the pond and let it loose. If you put an M2245 in that bird it will really scoot. Viel gluck
 

thomas

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I am pretty bad in 3D cad so I made a wood model of the AV-bay for the TAP inspection and for finding mistakes in the cutting files.
This is the top view of the bay, I will probably add a second u-bolt to have a symmetric attachment for the main.
The red part is the servo relase, another one will be installed in the cutout. Also the hole for the tube holding the Telemega antenna is missing. The bulkhead has a groove which matches the coupler inner diameter.
av_bay_top_wood.jpg
This is the side view, with a dummy paper electronic sled. The yellow GFK tubes are the gas seals for the servo releases. The aluminium angles have holes for m6 threaded rods through which the bay is attached to the booster. They have also grooves for GFK tubes which will guide the metal rods.
av_bay_side_wood.jpg
The angles are my first try of milling aluminium.

This is the setup for the primary electronic which will be an Altimax G3.
backup_elektronic.jpg
The Telemega will be the backup, since it is version 1 it can not control servos directly (the new version can do it), therefore it needs a spactec servocontrol to drive the SRM2.
primary_electronic.jpg
All electronics will be switched by Altimax magswitches. Both altimeters can fire both charges. Batteries will be 1000mAh not 100mAh as show in the figure.
 

thomas

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I am pretty bad in 3D CAD so I made a wood model of the AV-bay for the TAP inspection and for finding mistakes in the cutting files.
This is the top view of the bay, I will probably add a second u-bolt to have a symmetric attachment for the main.
The red part is the servo relase, another one will be installed in the cutout. Also the hole for the tube holding the Telemega antenna is missing. The bulkhead has a groove which matches the coupler inner diameter.
View attachment 297528
This is the side view, with a dummy paper electronic sled. The yellow GFK tubes are the gas seals for the servo releases. The aluminium angles have holes for m6 threaded rods through which the bay is attached to the booster. They have also grooves for GFK tubes which will guide the metal rods.
View attachment 297529
The angles are my first try of milling aluminium.

This is the setup for the primary electronic which will be an Altimax G3.
View attachment 297532
The Telemega will be the backup, since it is version 1 it can not control servos directly (the new version can do it), therefore it needs a spacetec servocontrol to drive the SRM2.
View attachment 297531
All electronics will be switched by Altimax magswitches. Both altimeters can fire both charges. Batteries will be 1000mAh not 100mAh as shown in the figure.
 

Tonimus

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That's a might fine looking electronics bay.
 

TMJ

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Best of level III luck to you, Thomas! You've put a lot into your project and it looks really good! I'm quite sure that you will succeed. Keep up the good work and try not to worry too much. Have confidence!
"Ich habe gelernt, das Wort "unmöglich" mit größter Vorsicht zu verwenden."
Wernher von Braun
 

grandcross

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Question: I see you're using servos in a hold back configuration to release the chute. If one fails due to an electronics malfunction, will it fail to release? It seems to me this will only work if both the primary and backup both release
 

thomas

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There will be a loop between the servos and a quick link over the loop. So if one servo opens the quicklink will slide from the loop.
Similar to this:
 

NateLowrie

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There will be a loop between the servos and a quick link over the loop. So if one servo opens the quicklink will slide from the loop.
Similar to this:

That makes a lot of sense. Shame there isn't a 2 servo unit with this already built in. Regarding the SRM, is there an english page where I can view information about it? I found what looks to be a german page and that's about it. Also, are these available in the US?
 

blackjack2564

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That makes a lot of sense. Shame there isn't a 2 servo unit with this already built in. Regarding the SRM, is there an english page where I can view information about it? I found what looks to be a german page and that's about it. Also, are these available in the US?

Google............. translator I used "Bing"....enter German to English. Put address of German page into address bar provided.

Voila! You can translate entire websites this way.[cut & paste address]

Here ya go translated site for altimeter:

http://www.microsofttranslator.com/bv.aspx?from=&to=en&a=http://www.rocketronics.de/produkte/

Just paste the SRM address in translator on top.
 
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thomas

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As far as I know there is not even a german page about the SRM2.
But the manufacturer is a TRA TAP, his company is:
http://www.spacetecrocketry.com/indexE.html
He had plans in the past to produce a version with two servos for redundancy, but I have not heard anything from it for years.
 

thomas

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So I had some setbacks.
The only German TAP on the TRA list is no longer a TAP, but he will borrow me a case and a launch pad.
Luckily we have a new TAP in Germany.
I was not able to get the second SRM2, so I am now switching to a Tender decender for the backup, which simplifies the electronic section a little bit and it is better to have two different devices for redundancy.
My CNC mill died today, but a new motor will hopefully arrive soon.

I have started to assemble some parts, here is a picture of the test fit of the fincan.
trestfit2.jpg
The good thing is you do not need any external jig for alignment, since they are aligned by the fincan, mostly by the grove in the top and bottom centering ring.
testfit.jpg
And this is the fincan with the stringer laminated to the motor tube. I had planned to foam the fincan but I might omit that it seems to be pretty strong already. Looks very messy, but it is actually very few epoxy.
glued.jpg
 

Steve Shannon

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Nice looking construction. I just sent you a pm about the TAP list.
Thanks,
Steve


Steve Shannon
 

thomas

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So I started gluing the fins in:
fin_before_glueing.jpg

I also completed most of the electronic bay:
One side has a Telemega with a Magswitch, the antenna protrudes through the lower bulkhead into the booster.
ebay1.jpg
the other an Altimax also with a Magswitch
ebay2.jpg
this is the side view, which shows the wiring
ebay3.jpg
and this is the view of the top bulkhead
ebay4.jpg
tubes to guide the threaded rods from the lower bulkhead are still missing.
 

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rharshberger

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So I had some setbacks.
The only German TAP on the TRA list is no longer a TAP, but he will borrow me a case and a launch pad.
Luckily we have a new TAP in Germany.
I was not able to get the second SRM2, so I am now switching to a Tender decender for the backup, which simplifies the electronic section a little bit and it is better to have two different devices for redundancy.
My CNC mill died today, but a new motor will hopefully arrive soon.

I have started to assemble some parts, here is a picture of the test fit of the fincan.
View attachment 319022
The good thing is you do not need any external jig for alignment, since they are aligned by the fincan, mostly by the grove in the top and bottom centering ring.
View attachment 319023
And this is the fincan with the stringer laminated to the motor tube. I had planned to foam the fincan but I might omit that it seems to be pretty strong already. Looks very messy, but it is actually very few epoxy.
View attachment 319024
That's a beautiful rendition of fin pockets!
 

thomas

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In the meantime I installed the guiderods for the M6 rods from the lower bulkhead.
I will also change to the 12 inch coupler instead of 14 inch to give the antenna more space, the metal rods have to be cut shorter for that.
ebay54.jpg

The lower Bulkhead has an opening (closed in the picture) just in case I have to do something below the bulkhead or if I want a Motor to protrude in the ebay in the future.
 

Tim51

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In the meantime I installed the guiderods for the M6 rods from the lower bulkhead.
I will also change to the 12 inch coupler instead of 14 inch to give the antenna more space, the metal rods have to be cut shorter for that.
View attachment 320060

The lower Bulkhead has an opening (closed in the picture) just in case I have to do something below the bulkhead or if I want a Motor to protrude in the ebay in the future.
That has to be one of the most beautiful avionics bays seen on TRF. Congratulations on a superb build.
 

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