|
|
|
|
|
Autor |
Nachricht |
g_boxwood
Anmeldungsdatum: 08.06.2006 Beiträge: 172
|
Verfasst am: Do 05 Jun 2008, 19:49 Titel: |
|
|
The cockpit on the plans (black outline) is really off-scale and I re-drew it according to 3 views of the aircraft (red line):
Next I made a lite-ply frame...
... and filled it with foam (I hate foam, did you get it?):
I'm now in the process to give this 'thing' a decent shape before glassing and finishing it to become a vacuum-forming plug.
_________________ Giacomo 'g_boxwood' Bosso
TRA#9986 L2
Zuletzt bearbeitet von g_boxwood am Do 05 Jun 2008, 20:15, insgesamt einmal bearbeitet |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
g_boxwood
Anmeldungsdatum: 08.06.2006 Beiträge: 172
|
Verfasst am: Do 05 Jun 2008, 20:09 Titel: |
|
|
Juerg hat folgendes geschrieben: | Hi Giacomo
"Long time no see"! |
I know, but I didn't quit, just turned to airplanes for a while.
Juergh hat folgendes geschrieben: | What motors are planned? A G12 is on the low side for take-off, unless you use two motors in sequence like on the test glider... |
That is THE point. Actually the real and only difference with the featured article is that WE'd like to launch it on the pad (60 to 45° above hor, 45° being already off rules).
The G12 and almost all the RC 32 mm reloads are rather weak in thrust so this is what I came up with:
[1] single 29 mm G38
[3] D12P in a cluster and/or
[3] D12-0 to [3] D12P or [3]E9P
Juerg hat folgendes geschrieben: | Why a 60mm motor mount?
Sounds like a very weird selection?! |
This is why I made my own 60 mm ID MMT so I can switch between motor configurations (from left to right, single 32 mm, 24 mm cluster and single 29 mm):
Both configurations sport out around 36 N avg. thrust which gives a 3:1 thrust-to-weight ratio with rather short burntimes... only the time will tell...
I'm building it to be towed so I can test-fly it before attempting more hazardous methods of getting it airborne.
I'll get you updated and this is why I posted.
BTW, this is how I molded my MMT:
. mandrel + mylar + first glass hose layer
. 1 mm balsa core
. second glass hose layer
. finished tube, mandrel and mylar
_________________ Giacomo 'g_boxwood' Bosso
TRA#9986 L2 |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
Andy
Anmeldungsdatum: 05.03.2005 Beiträge: 285 Wohnort: Russikon
|
Verfasst am: Do 05 Jun 2008, 21:22 Titel: |
|
|
Hi Giacomo
Wow, this is a really great construction!
You better don't tell us how much time you invested to design and build this rocket glider, but it's worth each second.
Which software did you use for designing?
|
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
g_boxwood
Anmeldungsdatum: 08.06.2006 Beiträge: 172
|
Verfasst am: Do 05 Jun 2008, 22:12 Titel: |
|
|
Andy hat folgendes geschrieben: | Hi Giacomo
Wow, this is a really great construction!
You better don't tell us how much time you invested to design and build this rocket glider, but it's worth each second.
Which software did you use for designing? |
Hi Andy and thank you for stopping by.
I usually draw in Rhinoceros and render in Penguin (non-photorealistic renderer sold as a plug-in for both Rhinoceros and AutoCAD): Rhino isn't the best available but it is fast-learning and complete.
http://www.rhino3d.com/
http://www.penguin3d.com/
_________________ Giacomo 'g_boxwood' Bosso
TRA#9986 L2
Zuletzt bearbeitet von g_boxwood am Do 05 Jun 2008, 22:41, insgesamt einmal bearbeitet |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
g_boxwood
Anmeldungsdatum: 08.06.2006 Beiträge: 172
|
Verfasst am: Do 05 Jun 2008, 22:15 Titel: |
|
|
Juerg hat folgendes geschrieben: | Hi Giacomo
Well, have you ever considered one G12 plus some "booster" for launch.
This could be either a ring of 18mm Blackpowder motors around the G12 (I don't think there is enough space) or some "drop-off" booster staging to the G12, like seen on Tomahawk cruise missiles.
You also could use a "drop-off" booster under the belly like it was used on Matador.
Booster recovery released after it was dropped, to stay safety-code compliant.
Once launched the G12 will be great for a scale-like flight.
Or a catapult of course.
Unfortunately the 60mm mount doesn't leave space for two G12's...
Another option: G12 and F39 one above the other, the F39 beeing a booster for Liftoff... |
Many useful hints, I'll consider each of them!
What about the single G38: do you think it is too much or not scale enough (due to the rshort burntime)? Single=simpler=more reliable=safer, this is why I preferred it.
_________________ Giacomo 'g_boxwood' Bosso
TRA#9986 L2 |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
Juerg Site Admin
Anmeldungsdatum: 27.02.2005 Beiträge: 4545 Wohnort: Oberengstringen
|
Verfasst am: Do 05 Jun 2008, 22:28 Titel: |
|
|
g_boxwood hat folgendes geschrieben: | What about the single G38: do you think it is too much or not scale enough (due to the rshort burntime)? Single=simpler=more reliable=safer, this is why I preferred it. |
The G38 will be a good motor to start with, to trim the aerodynamics. But the burn is only 2 seconds, compared to the 7 seconds of a G12...
Cheers
Juerg
_________________ http://www.SpacetecRocketry.com |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
Guido
Anmeldungsdatum: 06.03.2005 Beiträge: 136 Wohnort: Kloten
|
Verfasst am: Fr 06 Jun 2008, 8:29 Titel: |
|
|
Ciao Giacomo
Cant talk at the moment, still searching for my jaw, which droped somewhere below the table... Just great what you're building...!
Regards
Guido
_________________ No pain, no gain... |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
Juerg Site Admin
Anmeldungsdatum: 27.02.2005 Beiträge: 4545 Wohnort: Oberengstringen
|
Verfasst am: Fr 06 Jun 2008, 12:44 Titel: |
|
|
g_boxwood hat folgendes geschrieben: | Juerg hat folgendes geschrieben: | The G38 will be a good motor to start with, to trim the aerodynamics. But the burn is only 2 seconds, compared to the 7 seconds of a G12... |
I was a bit more optimistic about the burntime, I was thinking about 3-4 seconds... dunno why!? It's 2.1 as you said and it is way too short... |
I can tell you why: In the printed catalog there is a misprint of the G38 thrust curve, scale on the time axis is wrong.
As far as ignition is concerned, G-Wiz can handle this. You may need an external Relay Board to switch a high-current (12v) battery, but assuming you will need nose weight anyway, this shouldn't be a problem.
Or some own electronics... as you don't really need more than launch detect and timing.
Cheers
Juerg
_________________ http://www.SpacetecRocketry.com |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
alessio
Anmeldungsdatum: 05.09.2007 Beiträge: 1071 Wohnort: Carasso
|
Verfasst am: Fr 06 Jun 2008, 14:48 Titel: |
|
|
g_boxwood hat folgendes geschrieben: |
In case of an air-start: is there any commercial unit that could fire the igniter safely and reliably via servo input (mechanical) or via the receiver (interpreting the servo impulse of the assigned channel, PPM or PCM or both, as the 'fire' instruction)? Is there any?
Thank you Guido! |
looks like stefano may have something....
http://www.sierrafoxhobbies.com/catalog/product_info.php/products_id/875
or you can try to use a "old"regulator for brused motors..
they can handle a lot of current..
alessio
_________________ alessio
MO13
TRA11158 |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
Juerg Site Admin
Anmeldungsdatum: 27.02.2005 Beiträge: 4545 Wohnort: Oberengstringen
|
Verfasst am: Fr 06 Jun 2008, 17:06 Titel: |
|
|
Unfortunately this unit won't do it (as is). It is designed for e-matches but Giacomo needs Magnelites.
So lots of current for considerable time and specially: 12V!
But Stefano's unit could drive a relay...
Also, strictly speaking an RC Control is not needed and adding a point ud uncertaincy (hitting the right moment).
All what is needed is launch detect (trip wire in parallel to arming switch) triggering a 1-2 second timer triggering a 1second duration high current relay for ignition. (Ignition circuit again with safety switch)
A simple NE556 and some external elements can do this.
The difficult part is the battery: 12V, lightweight, high current.
But as there is only one motor to ignite one or two 9V Alkaline blocks may work. This needs to be tested, as a fast and predictable ignition is required.
If there is not enough current, the magnelite may take a second or two to light.
If there is too much voltage (tricky point with 2 9V blocks) the igniter may spit away its pyrogen instead of lighting it.
Cheers
Juerg
_________________ http://www.SpacetecRocketry.com
Zuletzt bearbeitet von Juerg am Fr 06 Jun 2008, 20:21, insgesamt einmal bearbeitet |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
g_boxwood
Anmeldungsdatum: 08.06.2006 Beiträge: 172
|
Verfasst am: Fr 06 Jun 2008, 19:14 Titel: |
|
|
Alessio: that's exactly what I meant! Thank you 'cause I never noticed it!
Juergh: what about the above unit with e.matches as igniters?
I used them twice to light some J135Ws I had no luck with Magnelites but I was not the one who made them: they belonged to J. L. Sanchez and they worked pretty fine.
I regret using a 12V battery on board... a Li-Po @ 11.1 V may work but I don't have any. Again, e.matches as igniters and a single or double 9V may do the job.
I'm talking about air-starting after a regular tow to height (less critical) or after a bungee-launch (more critical).
_________________ Giacomo 'g_boxwood' Bosso
TRA#9986 L2 |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
Juerg Site Admin
Anmeldungsdatum: 27.02.2005 Beiträge: 4545 Wohnort: Oberengstringen
|
Verfasst am: Fr 06 Jun 2008, 20:24 Titel: |
|
|
Giacomo
E-Matches to light J135?
But not the e-match alone then! The don't generate enough heat.
The problem ist that a J135 has a rather large nozzle, hwoever you will not even be able to insert an e-match into a "G" motors nozzle.
Cheers
Juerg
_________________ http://www.SpacetecRocketry.com |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
Autor |
Nachricht |
Andi Wirth
Anmeldungsdatum: 27.02.2005 Beiträge: 1317 Wohnort: Sirnach TG
|
Verfasst am: Fr 06 Jun 2008, 20:29 Titel: |
|
|
Hi Giacomo
Great Plane that you're building!
In my glider I used a normal controller for R/C electrical powerd models. 8 cells of a NiCd or NiMH battery are enough for a first fire or Magnlight igniter. Maybe that could fit for your needs?
Andi
_________________ Das Leben an sich ist lebensgefährlich und endet unweigerlich mit dem Tod. Es sollte verboten werden. |
|
Nach oben |
|
|
|
|
|
|
|
|
|
|
|
Du kannst keine Beiträge in dieses Forum schreiben. Du kannst auf Beiträge in diesem Forum nicht antworten. Du kannst deine Beiträge in diesem Forum nicht bearbeiten. Du kannst deine Beiträge in diesem Forum nicht löschen. Du kannst an Umfragen in diesem Forum nicht mitmachen. Du kannst Dateien in diesem Forum nicht posten Du kannst Dateien in diesem Forum herunterladen
|
|
|
|
|
|
|
|