Wicked powered SR-71 - Page 67 - RC Groups
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Mar 15, 2012, 03:09 PM
Shameful Warbirdaholic.
Aros.MotionRC's Avatar
Question about the O-rings...Are they really necessary? Do they simply help stabilize the thrust tubes under high vibration?
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Mar 15, 2012, 06:30 PM
Registered User
Joe 1320's Avatar
Quote:
Originally Posted by Aros
Question about the O-rings...Are they really necessary? Do they simply help stabilize the thrust tubes under high vibration?
Actually, the afterburnerz with their raised LEDs offer support to the thrust tubes. One customer decided not to use the centering rings, he just installed the afterburners and the thrust tubes slipped right in and were held in place perfectly. With the support of the afterburnerz, I would say that the centering ring is necessary.
Mar 15, 2012, 06:45 PM
Shameful Warbirdaholic.
Aros.MotionRC's Avatar
Interesting...I don't see how the raised LEDs are supporting the thrust tubes? Am I missing something? On a good note, even with the tear in one of my tubes, I tried a WOT test today and they held great! The LED kit needs to be lightly CA'd in spots to keep from moving around though...I just don't want to glue them too much in the event I need to take them out like last time where the wiring ripped out...
Mar 15, 2012, 07:28 PM
Registered User
Joe 1320's Avatar
Quote:
Originally Posted by Aros
Interesting...I don't see how the raised LEDs are supporting the thrust tubes? Am I missing something? On a good note, even with the tear in one of my tubes, I tried a WOT test today and they held great! The LED kit needs to be lightly CA'd in spots to keep from moving around though...I just don't want to glue them too much in the event I need to take them out like last time where the wiring ripped out...
Don't use CA. Use a silicone type foam safe glue. You could use some clear gorilla glue (polyurethane), GWS glue,, I've seen good results with a glue found at Michael's that is a white, foam safe glue. I'll dig up the name of it when I get back in the states.
Mar 15, 2012, 07:31 PM
Shameful Warbirdaholic.
Aros.MotionRC's Avatar
Oh good idea...I have a glue gun too...
Mar 15, 2012, 07:32 PM
Registered User
Joe 1320's Avatar
Quote:
Originally Posted by Aros
Oh good idea...I have a glue gun too...
There ya go...... a few drops of hot glue will work great.
Mar 15, 2012, 07:33 PM
Shameful Warbirdaholic.
Aros.MotionRC's Avatar
I rely on CA and epoxy waaaay waaaay too much.
Mar 15, 2012, 07:36 PM
Registered User
Joe 1320's Avatar
Quote:
Originally Posted by Aros
I rely on CA and epoxy waaaay waaaay too much.
I must have 12 different types of glue in my adhesive box. Different types of CA, different types of Epoxy, foam safe glue, polyurethane, hot glue, you name it......
Mar 15, 2012, 11:51 PM
Shameful Warbirdaholic.
Aros.MotionRC's Avatar
My high start arrived tonight. I realized the tubing was the smaller diameter but I think it should be okay still. It's pretty resilient and strong rubber tubing. Besides AUW on the Blackbird isn't much if any heavier than a lot of the 2M-3M sailplanes these high starts are meant for.

One thing that I have been thinking about lately is the location of the tow hook. I'll have to do my research but I'm fairly certain the sweet spot is somewhere just in front of the CG. The problem is, on this plane, just in front of the CG is the receiver compartment. There's nowhere to mount a tow hook there. I may have to mount some thin wood like a bracket that spans perpendicular to the length of the compartment with epoxy, strong enough to support a tow hook and its use.

Well, I'm still a good two months out before official flying season hits here in the Pacific Northwest so that should give me ample time to find the right solution and setup. I can't botch this. A bad hand toss and you're gluing the front end back together. A bad high start launch and your picking out the electronics and throwing the rest of the plane into a plastic bag.
Mar 16, 2012, 11:41 PM
Indoor Free Flight Modeler
Finished my SR-71. The maiden will be tomorrow. We are having unusually warm weather in Ohio this year for March, no snow and 65 degrees and 5 mph wind for the morning :-)

Is the recommended CG on the MaxJet correct or at least close? Ran it up on two 4S 2200 lipos and about 1:1 at just over half throttle :-)
Mar 17, 2012, 08:50 AM
Registered User
sanman55's Avatar
Wow...that baby is ready to go....what was your final weight???
Have a good maiden
Mar 17, 2012, 09:27 AM
Indoor Free Flight Modeler
29.3 ounces with no lipo, 48.4 ounces with two 4S 2200 40C lipos.

Don
Mar 17, 2012, 11:38 AM
Build'm,Fly'm,Crash'm
redlite's Avatar
[QUOTE=

Is the recommended CG on the MaxJet correct or at least close? QUOTE]

Can't say, Don, I have both versions, but only built the LX...seeing how MJ copied everything else on the model, I would figure the CG is the same.

Good luck on the maiden...

Joe
Mar 17, 2012, 03:32 PM
Indoor Free Flight Modeler
Maiden was a success! CG was spot on. I forgot how cool a SR71 looks in the air. It really slows in turns if you get to tight so best to make larch flat turn with this one to keep it up on step. I was expecting more speed for the watts though, I wonder if all the surface texturing on this model is slowing it down. I don't recall the LX version having all the molded in detail.
Mar 17, 2012, 03:55 PM
Build'm,Fly'm,Crash'm
redlite's Avatar
Congrats, never doubted it...

The LX has more surface detail than the MJ, which makes it better for scale looks, if needed...MJ also has a smoother foam finish and shiny paint, better for speed models.

Most draggy model we have...shut the power off when it goes overhead so you can hear the air resistance and be prepared for a sound you're not expecting, being a SR-71 and all...

Joe


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