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TwinJet to Rocket Propelled/Ever been done?

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TwinJet to Rocket Propelled/Ever been done?

Old 08-07-2006, 11:25 AM
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TheJester
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Default TwinJet to Rocket Propelled/Ever been done?

Ok, I'm posting some pictures of what I'm trying to do here, but I'm wondering if anyone else has attempted this as well. I'm taking a Twin Jet that will take off and land via hand launch like normal. Then, while in flight and triggered via RC I am going to ignite a perminenantly attached "G" sized ROCKET reload kit and see what happens.
The first photos, in white, are when I had a Hacker A20-20L motor connected to the rear with a 11x4.7 prop. The plane flew great, but not all that fast, so I switched to a20-6xl with 5x5 prop instead of the designed 2 480 brushed motors. When I had it there, the plane flew perfectly and FAST, but I was afraid that when igniting the rocket, it would either damage my motor or burn the prop off, so have moved it to the forward position ahead of the rocket. I'm now trying to balance it out to fly then work on the ignition system.

Let me know any input as I need help with the ignition system that will require 12volts and weight is a MAJOR issue.

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Old 08-10-2006, 12:08 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Ok, maybe this project only interests me or no one wants to think about it.
Old 08-10-2006, 12:31 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Yes, stuff like this has been done before. Looking at your pics, I'd suggest joining the rocket boost gliders forum on yahoo groups, and checking out the motor mounts. Nylon straps won't keep a "b" engine in place, much less a "G". Most mounts involve your traditional cardboard tube, epoxied into plywood mounts. This motor will produce a phenomial amount of thrust for a short time. Most typical model rockets accelerate to almost 350-400 mph by the time they hit the end of the launch rod - that's 36"!!!! Most of the plans, write-ups
I've read have cited wing failure due to the extremely high G-loads encountered - ie. they get ripped off on launch. You may have to use glass reinforcing tape an the leading edges/spars. Weight is a critical factor, but so is strength.

And good luck

PS - I've got both the Estes Astroblaster and Stratoblaster. They're still in the box, but I've studied the instructions for possible motor upgrades - I'm a power-freak too
Old 08-10-2006, 12:43 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Yeah, on our first test of the smaller reload kit, test fire on the ground, the nylon zip ties melted, so it has now been changed to a slab of balsa between the foam and rocket epoxied down. Then I used the Epoxy putty to attach the reload kit to that.

The over all deal is that I understand the rocket gliders, but what we are trying to do here is, have the plane take off, land, and even fly around like normal first and last, but in the middle ignite the rocket via GER/FLAP switch.

Thanks for the leading edge info, I will give them a thorough coat of epoxy then covered in Strapping tape, like I did with my Combat Wing.
Old 08-10-2006, 12:48 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Try a search on RCU for Bell X-1 - a while back some guys built one for launch from a B-29.
Old 08-13-2006, 12:46 AM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Contact Doug at RetroFlight.com he can help you out email [email protected].l
Retro Flight designs and fabricates small to large Rc rocket gliders. Specialized in X-15's.

Old 08-16-2006, 10:41 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

here is the idea: http://www.ratpackinternational.com/...ComingSoon.mpg
Old 08-18-2006, 12:11 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

I am currently working on a rocket propelled park zone stryker with estes E sized motors. It will be a two stage deal. One motor to get it up and another to use while in flight. G motors are very powerful. I had a 2 meter spririt great planes glider rocket propelled with an F motor and it was too much for it. It worked, but just barely. The wings flexed tremendously and due to the motor placement, it would do a violent loop and not a straight up and away type deal. In one flight the motor didn't ignite in flight like planed, so the plane landed. The motor ignited as soon as the plane came to a rest. An F motor had enough power to take off( from grass) this big glider, loop the plane in about a 20 ft loop and ascend another 15 ft. I am not saying a G motor can't work, especially since you will have battery and motor weight, but these high power motors are very violent. Be sure to compare your plane's weight to a G rocket's weight. I haven't figured out the ratio with respect to how much heavier to have the plane in comparison to a rocket using an equal motor, but the plane should be heavier. Going back to my 2 meter glider, I later tryed E sized motors, which worked a little better and they are easier to get and use. This plane eventually sustained severe fire damage as my motor mount loosened and the blast caught the bottom of the tail. I am very interested in your project, keep a rocket plane thread alive. If you are interested in my set up I would be more than happy to post some pics, just let me know.

Alex.
Old 08-18-2006, 12:41 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Sweet another pilot that is a "little off his rocker" and willing to take some risks, like me. Yes, I would be interested in seeing your set up. When you say you are launching from the ground, are you launching with a conventional system, IE: car battery, or do you have an onboard switched controled ignition system?
Old 08-18-2006, 01:11 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

The Loop was most likely a result of off center thrust, camber air foil or CG/Cp shift. Airfoils with camber will loop so be prepared to correct for it quickly. If motor is located off of the centerline (further from CG/Cp location the more pronounced the effect) the model will loop. Best to locate the motor close to CG/Cp location or if aft of model angle the motor so the thrust line passes between the CG and CP locations. Composite motor propellant burns quickly which results in a sudden CG/CP (weight) shift in the model. If the motor is located near the aft end the shift will be more violent. Delta platforms seem to handle the CG/CP shift best and often do not require ballast dump to compensate. Straight or swept wing models may require ballast dump (water bottle) to work. Or again locate the motor close to the CG location.
Old 08-18-2006, 03:08 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

I have an on board ignition system. I use estes ignitors that are connected to a toggle switch which is hit with a servo arm. The switch then opens the circuit to the receiver battery which then applies power to the ignitor. I used to custom build ignitors for my F motors to ignite them in the same way. It works quite well. I will try and post pics. As for my glider, I had a rocket pod bolted right on the C.G. to eliminate weight issues. My current project is a balancing act. The receiver battery is positioned in such a way that the plane is slightly tail heavy with two full motors and slightly nose heavy with the two empty motors. I have the motors mounted in the same position as your twin jet project.
Old 08-18-2006, 03:32 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Ok, I have that same type of switching set up, but you are using the power from the Receiver, not another source and it is enough to ignite? On early tests that is what caused us some difficulty as we were using a separate 9v battery and it didn't seem to have the gusto to ignite the rockets or the igniter itself. I'm trying to ignite a G79W-m motor with Aerotech 1st Fire Jr. Igniters.

Ok, next question, are eithe of you using reload kits? The reason I ask is becuase how are you running the wiring to the ignitors. I'm not using the blast cap, but I am using the delay, so I'm guessing that I can just fill in the hole at the top of the motor so flames are not shooting forward burning up my plane.
Old 08-18-2006, 03:45 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

I use the Jomar switch its electriclly isolated from the receiver and uses a seperate battery pack (two or more 50 mAh cells). Don't use a standard 9 volt it will not fire composite ignitors and questionable on Estes nichrome solar ignitors. Always use NiCad cells they have way more kick. The Jomar switch keeps your Rc servo from being effected by the air-start or vice-versa. Weight of the xtra battery pack is small , can be used to offset the rocket motor weight. Test out your system on the ground first to ensure it will fire the ignitor. For composites I use the Quick-Burst brand ignitors.
Old 08-18-2006, 04:04 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

I use composite reloads, I just add a little molding clay to plug the eject delay hole. Then I use the black powder charge to deploy my back-up cute if needed. I've never done jet to rocket but I have done rocket boost to EDF power. The rocket boost saves on the EDF battery (no take-off) so you have more powered flight time. One could mount the rockets like JATO units on any jet model (be sure to aim or use ceramic deflect nozzle to direct thrust toward CG/CP center). Cpould use the ejct charges to drop tehj JATO units and open small chutes on them. Never done that but have been thinking it.

Cool models and fun ideas!

Retro!
Old 08-18-2006, 04:51 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

ok, well, been doing some test "tossing" and I think I got it all retrimmed out and balanced. I don't have the reload kit in yet, but I do have the casing epoxy clayed onto it. Should be some sort of action soon, but raining right now.
Old 08-19-2006, 02:23 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Well, actually pulled out the Aerotech 1st Fire Jr. Igniters and tested them with a 9-volt and it worked swimingly. So have now got it all wired up, as shown below. Now I have to figure out how to get them into the rocket case with the nozzle on, and for the wind and rain to stop.
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Old 08-19-2006, 03:05 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Looking good there! Should be an exciting flight to pilot. Launching rockets is always a bit tense, but to actually pilot the rocket is the next level. Especially the first time one fires up a new design. . .. a real rush! So where is Clive IA? I'm in Atlantic IA southwest part of the state. We should meet up sometime at a rocket launch or Rc field and punch some holes in the sky.

Retro
Old 08-19-2006, 05:00 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Clive is in DSM, but I spend most of my time down in Fairfield, Iowa, just south of Ottumwa. That would be cool. There was supposed to be a fun fly in Ottumwa at the airport today, but the weather kind of killed that idea. They do them every second saturday of the month from what I understand. My buddy, Natch, and I are Team FMF and are all about pushing the limits.
Hoping to get this thing off the ground and fired tonight, will post video once it is done. Crossing fingers and headed to Walmart to find a fire extinguisher now.
Old 08-20-2006, 10:58 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Well,..........uh, 2 out of the 3 things I wanted to do, did, but the 3rd one was, well, exciting, to say the least.
1. I WAS able to get the twin jet to fly even after moving the prop motor forward and cutting that big hole in the delta part of the wing.
2. After getting the plane into the air, and ground testing, I WAS able to get the igniter to ignite and ignite the rocket via RC using my servo/9-volt battery set up.
3. and then it goes down hill. I admit the plane was a little floatie and I should have maybe retrimmed it as it was running a little tail heavy. Anyway (mind you my VIDEO GUY failed to get the shot), so I make my final pass, getting the plane aimed toward open area and away from people, long with a slight upward angle. Instantly after ignition, the twin jet did about 8 VERY TIGHT loops. With no video I don't remember if it was inward or out so I don't know how to make the corrections.

So, 2 out of 3 isn't bad, from what I hear, for still trying to do something like this that hasn't been done before.

Oh well, back to the drawing board.
Old 08-20-2006, 11:53 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Great effort! Hang in there maybe start with smaller motor next time and build up to higher impulse gradually? Though adjusting CG each time might be frustating.

Retro
Old 08-21-2006, 03:08 AM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Yeah, looking back I should have landed and shifted the battery forward, but having thrown it off the deck to only nose dive hundreds of times to try and find the CG, I guess I was just caught up in the moment and thought that if I landed it might not get back in the air for some reason. Been working on this for 2 months now.
Have to wait, as I have all the reload motors for my smaller case, 29mm, but am waiting on them to send me a new enclosure ring because when we tested it on the ground it blew it off and we never found it. Apogee, of course, doesn't make the component needed, Aerotek does and I'm to wait 3-4 weeks for them to MACHINE one out for me.
On the other hand, my Giant reload casing, has all the parts, but now I'm waiting on more reload motors to come. Oh well, I have other projects up my sleeve. It's off topic, but I just got done with this one too: www.ratpackinternational.com/nightflight.mpg
Old 08-22-2006, 06:46 AM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Actually, after some late night beer drinking thought, instead of waiting for the missing pieces to come, I think I'm going to just strap one of my little sisters rocket kits to my plane. They are extremely light, aerodynamic, and I know how to do the ignition system Video to come if the weather permits today.
Old 08-22-2006, 10:17 AM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

ha, simple set up, looks like this: www.ratpackinternational.com/rocketwing.mpg

Weather is looking perfect, off to get video of this attempt.
Old 08-22-2006, 04:07 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Well, that was freaking easy enough. I was apparently over complicating the whole thing. The weight to thrust ratio is WAY under for this little rocket motor on this big of wing, but I got the 9-volt/servo set up with Aerotech 1st Fire Jr. Igniters to work like a CHARM with a B6-4 motor and and C6-5, but I think I need to do it again with the prop on brake to keep from slowing it down. The B didn't do much to it, but the C definitely did something besides just turn my 6x5.5 prop into a 2inch prop. Going back tonight with more C's cause that is the biggest I can get at Walmart, the only store in town, and experiment with some dives and no prop, maybe some low fly by ignitions since it is WELL controlled. Here's what I got so far:
www.ratpackinternational.com/bandcrocketwing.mpg
Old 08-22-2006, 05:34 PM
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Default RE: TwinJet to Rocket Propelled/Ever been done?

Looks like fun! Now that's test flying, once stability has been established at the current motor size bump it up to a Estes "D", or composite Aerotech "D" etc...
Wonder if a folding prop would work? Great video looks like you found the sweet spot for CG/CP location. Burn a hole in the sky HOT DOG!!!!!!!!!!!!

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