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Sep 19, 2011, 01:24 PM
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Hepdog's Avatar
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Space Shuttle Enterprise - Part II - with flying ET

This is my third attempt at making a flyable Shuttle with ET and SRB's. I tried once about 5 years ago and arguably both my ability and technology just wasn't there yet. I also made the mistake of making it purty before making it fly. CofG and control issues were the problem. It "flew" once but was largely uncontrollable and underpowerd. Limited video here:

35888outtakes.mpeg (0 min 36 sec)

Last winter I built a mini-Shuttle with flyable ET/SRB combo and it worked really well. Video is here:

Mini Shuttle and ET.wmv (0 min 46 sec)

This time, I'm making it functional and ugly to sort out the balance and control. IF this all works as planned, I'll scale it up a bit more and make it purty over the winter.

Shuttle details - my original Shuttle (from 5 years ago) was still mostly intact (severe hanger rash). Decided to drop the pusher prop and go EDF! Power is from a 50mm Don's Wicked WEmo EDF - about 25 amps on 3s. Test flew that today and it goes like stink! No real vertical power but that's fine. AUW is about 15 oz.

ET/SRB details - decided to try thrust vectoring as well as aero controls. Either one alone will not work. For this one two Grayson SMJ's spinning CR APC 6X4's ought to be a good start (about 600 watts or so). By putting the motors on top of the SRB's I gain alot more CofG room to play with. If that isn't enough power I can put another motor on top of the ET. If that isn't enough I can stick a motor on the bottom of the ET. If that isn't enough.......

I learnt alot flying the little guy. To deal with the CofG shift when the Shuttle departs I might use a sliding box for the batts. On the little guy it was set up a touch tail heavy with the Shuttle on and very nose heavy with it off. This works but isn't ideal - I want to fly the ET/SRB down for landing. BTW this will require 2 pilots to fly

More pics to follow as it progresses. Unfortunatley I DO NOT build from plans and do not offer plans to this one.
Last edited by Hepdog; Oct 02, 2011 at 11:28 PM.
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Sep 26, 2011, 08:51 PM
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After thinking and tinkering I decided on how to get the thrust vectoring I figure should work. I'm going to stick with elevon controls for now which means a couple things:
- the aero controls and motors will always be coupled together. I could go with a fancy mix but I don't think it will be required. I think I will have an undercontrol situation as is. Can't wait to try a foward CofG with both motors pulling the nose up
- NO gyros Can't use gyros with elevon mixing so it will have to fly on it's own. The little guy was actually pretty stable so I don't think this will be an issue.

Now I just have to run some rods to the elevons, slap on some temporary landing gear and mount the batts. Should be able to maiden just the ET/SRB soon - whenever the wind cooperates.
Last edited by Hepdog; Sep 26, 2011 at 09:00 PM.
Oct 02, 2011, 11:27 PM
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Getting closer - got the elevons all hooked up. Still have to add the rudder servo and then try to fly it....

AUW is just over 3lbs - should fly okay.
Oct 03, 2011, 06:39 AM
LOOKING GOOD. are tanks going to drop with shute & SUTTLE land. ps i got shuttle efd powerd flys great
Oct 03, 2011, 02:54 PM
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Originally Posted by space 1
LOOKING GOOD. are tanks going to drop with shute & SUTTLE land. ps i got shuttle efd powerd flys great
No the plan is to fly the ET/SRB up with the Shuttle, drop the Shuttle, and then FLY the ET/SRB combo back for a landing. My first try 5 years ago was to drop the tank but that actually proved more difficult than this way.

BTW, maidened the ET/SRB combo today. Some small trim issues and it will need more power for the expected vertical climb (especially with the Shuttle on back) but it does fly fine just like the little guy did. Off to the LHS for another big ESC for a bigger nose tank motor.

Vid to follow as soon as I figure out how to edit .MOV files.
Oct 03, 2011, 03:04 PM
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astronaut's Avatar
This is right up my alley, loving this!
Oct 03, 2011, 09:04 PM
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Got some video - second flight tests with 3 motors. Moved the CofG up an inch and she's rock solid now. Will likely move it back an inch for the Shuttle flights - makes it easier to go vertical.

Unfortunatly, even with 3 Grayson SMJ's pulling for all their worth, she's still a touch underpowered (For vertical with the Shuttle). Considering it's 5lbs auw and only 900 watts that actually makes sense. So I have two motors capable of 1000 watts EACH using the same batts so that should work out alright.... 2500 watts on 6 lbs ought to give me good vertical (400+ watts/pound).

Some quick vids for proof of flight. Today was so productive maybe I can beat the 747 boys.

Space Shuttle Launch vehicle ETsrb test mule.MOV (1 min 34 sec)

EDF Shuttle landing.MOV (0 min 24 sec)
Oct 04, 2011, 05:55 AM
are you useing shuttle power for liftoff too. you got two rx & two pilot's
Oct 04, 2011, 11:41 AM
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Yup - I need two pilots when the shuttle separates. The next test flights will be Shuttle on tank but no separation (planned). For those flights I'll either just run an extention up to the Shuttle ESC to power it up or have both Rx's on the same freq and settings so I can control both from one TX. It's actually easier to fly the Shuttle if the controls don't move - some really odd coupling happens...
Oct 05, 2011, 08:31 PM
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Slow going today - +31 on October 05!!! Too nice to be in the shop.

Anyway, built up a catch and release mechanism. Again, not intended to be purty - just functional. I use two pawl type deals to grab and pull down on 2 bars on the Shuttle. This holds it firm for power up and aero loads etc. I used a similar deal on the mini and it released cleanly every time.

I also mounted up a bigger motor - good for 700 watts continuous - maybe 800 in burst. Have to try a couple different props and see what works.

Now I have to build the sliding batt tray. I figure it only needs to slide back about 5" to keep the CofG right. That big Turnigy balanced the rig w/o batts in! This should allow me to get the Shuttle further back for a more scale location.
Oct 11, 2011, 08:57 PM
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Another part day to spend tinkering.

Got the Shuttle holder all sorted out (I think). It will hold it upside down in the shop and releases well so hopefully that works.

Built a pretty crude battery sliding tray - again it doesn't have to be pretty this time around. I'm thinking a simple servo released rubber band type deal out to move it back far enough. It needs to slide a full 6" so no servo arm is going to do that. If any of this works, for the final version I'll use a fast worm gear - don't need this moving uncommanded.

As soon as the weather cooperates I'll re-test fly the ET with the new motor and then its on to flying with the Shuttle on back. Gotta find another pilot soon...
Oct 14, 2011, 04:11 PM
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Yet another part day of tinkering.

Decided to use a full size retract servo to move the batt tray. Built a 3" arm which gives me 6" of travel. It has plenty of power up to about 40 degrees of pitch - then it struggles. As long as I'm in near level flight when moving the batt it'll be fine.

My only concern is that when the Shuttle separates - it becomes very nose heavy. As long as I have enough pitch control to pull out of the ensuing dive I can slide the batt back and regain normal control. If not, it's going to make a nice smokin crater.

I will have to figure out something more foolproof for the final BIG version. I've already started some drawings for the next one - I'm thinking at least 8' long should be about right.
Sep 04, 2012, 07:34 PM
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I see this thread is more than 327 days old - life happens!

Anyway, had some spare time today to play around with the Shuttle and SRB - winds were 0 so why not!?! Right!

Loaded it all up and went out to our wide open flying field - alone so no vid or inflight pictures

However it does fly and flys good! Shuttle on ET was stable although the attachment points were not nearly secure enough - it was floppin around a fair bit - I thought it was gonna fall off but it didn't.

Power was enough for a 30 degree climb out We need way more power Scotty.

Now that I know it works I'm going to start on the 8' lighter version. Posts will trickle in slowly...
Sep 04, 2012, 08:02 PM
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Very cool Hepdog glad your sticking with it.I am proud to say I got to see one of the last liftoffs.LOUDEST thing I ever heard.Cant wait to see the next gen shuttle.Keep it up.

Sep 04, 2012, 08:55 PM
Rc planes having flown
HepDog thats the Coolest RC plane Ive seen in a Long-while!

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