Quest Terrier-Orion 2 stage conversion

[kmf04040]

I recently purchased a Quest Terrier-Orion from my lhs and am thinking about converting it to 2 stages. I read that Bill Stine had some success with spacing engines up to 12 inches apart and having successful staging by utilizing vent holes to relieve pressure to prevent the stages from separating before the sustainer ignites. Has any one tried this method of staging and/or has anyone successfully transformed this rocket into a 2 stage? I have made up a rocksim file and run simulations and know that it will be stable as a 2 stage rocket, but am unsure about reliable ignition of the sustainer.

[kruland]

I have done this. The biggest problem is the booster is stable and requires some form of recovery or else it will come in ballistic.

Construction of the sustainer is pretty straight forward. However, make sure the motor extends ~.25" and use friction fit so there is not a clip in the way.

The construction of the booster is quite a bit of a trick. Use a motor tube which extends the entire length of the booster and goes over the sustainer motor. I constructed basswood centering rings which were glued to the motor tube but slide freely in the booster body. The motor mount was teathered to the booster with a bit of kevlar thread. At the top of the motor tube I used a hole punch to create the vent hole. The vent hole is foreward of the top most centering ring. I wrapped a length of mylar streamer around the motor tube between the two centering rings.

When the booster burns out, the pressure and particles move forward simultaneously lighting the sustainer and pushing the motor tube out the back of the booster.

I can take pics when i get home.

[[POW]Eagle159]

I have done gap staging rockets before... 3'',6'',8'', and lastly 12 inches of space between engines. All have worked perfectly, The staging is quite reliable.
Next I want to go bigger with like a 15-18'' gap.

http://www.rocketryforum.com/showthr...-build-Details

http://www.rocketryforum.com/showthr...722#post342722

http://www.rocketryforum.com/showthr...TS-OF-PICTURES

The hard/interesting thing to overcome with gap staged boosters is the recovery... Pretty much any design will lawn dart if it doesnt have a chute or streamer. This is what happened too my 8'' gap booster, which was actually my first gap booster made, but it had no recovery device and after one flight the tube got destroyed.

Thats why I use larger tubes to hold chutes for my boosters, and it might be quite hard on a smaller kit like the Terrier-Orion. I dont know what the distance between engines would be, but its doable.

[kmf04040]

I noticed the booster stage itself seemed stable in simulations. I've already constructed a stuffer tube/ 24mm motor mount (the plan is to launch with a D12-0/ C6-7 combo) with 2 quarter-inch vent holes near the top. Rather than make centering rings, I made up some wood strips to center the tube within the sustainer airframe. I chose this approach as I felt it strengthened the entire airframe while allowing and debris to easily fall out of the rocket. Unfortunately, I never thought about how to destabilize the booster stage after burnout until after I glued it in place.

[kjohnson]

Check out the sliding booster mount I posted about here:
http://www.rocketryforum.com/showthr...335#post238335

This was a smaller version of a Terrier booster for a scale altitude contest. Should work fine for your Terrier Orion modification.

kj

[kmf04040]

Terrier-orion has been painted. Waiting for everything to dry before decaling and final details.

[foamy]

One thing you're going to notice is that the stripes aren't long enough to go around the rocket. I don't know why.

[JStarStar]

Gap-staged boosters usually have the problem of being stable after separation.

One way this can be fixed -- if the booster is not minimum diameter -- is to attach a streamer to the booster stage, wrap it around the motor tube, affix a very thin "pull thread" to the top end of the streamer, and use a very small tab of paper tape to attach the "pull thread" to the bottom of the upper stage.

When the upper stage ignites, the stages separate, and the streamer is pulled out by the "pull thread." When the streamer extends to full length the "pull thread" rips off the upper stage, which then continues on at full speed.

You obviously don't want the "pull thread" or the tape attaching it to the upper stage to be very strong, just strong enough to pull the streamer out of the lower stage.

[foamy]

JStaStarr, do you have experience with that technique? I'm wondering if when the "tab" pulls off the sustainer, does it pull it's tail around at all? Just wondering as that was a method I was considering for a future build. Maybe the string burns off? Streamer catches fire? Lots of "what if" questions I have. What has your experience been like?

[adrian]

Gap-staged boosters usually have the problem of being stable after separation.

One way this can be fixed -- if the booster is not minimum diameter -- is to attach a streamer to the booster stage, wrap it around the motor tube, affix a very thin "pull thread" to the top end of the streamer, and use a very small tab of paper tape to attach the "pull thread" to the bottom of the upper stage.

I've done something similar, but instead of wrapping the streamer around the motor tube, I wrap it half round, fold it back on itself, wrap round the other way, repeat until the whole streamer is wrapped in sections which individually don't quite go round the tube. The result is that the streamer just falls off the motor tube without needing any pull thread or attachment to the upper stage.

[JStarStar]

JStaStarr, do you have experience with that technique? I'm wondering if when the "tab" pulls off the sustainer, does it pull it's tail around at all? Just wondering as that was a method I was considering for a future build. Maybe the string burns off? Streamer catches fire? Lots of "what if" questions I have. What has your experience been like?

I've done it with a gap-stager made with a Big Bertha on top of a Baby Bertha as the booster stage.

The "pull thread" is stuck on the lower end of the upper-stage motor with a VERY small piece of tape (about 1/8" inch).

The upper stage Bertha does not appear to change course at all at staging -- it just takes off as usual. I suspect it would deflect if the "pull thread" was attached with anything stronger than a very flimsy thread.

The streamer does not exactly bring the lower stage down to a gentle landing -- it still comes down pretty fast. But at least it does not augur straight in nose first as it did without any recovery system.

The streamer sometimes gets slightly singed but it is flame-resistant crepe paper so it does not burn.

EDIT: Looking at Adrian's post I think with many models the "pull thread" might not be necessary, if there is some way to get the streamer out in the airstream where it will be pulled out by drag. But I tried my "Boosta Bertha" a couple times without the "pull thread" and the streamer usually stayed wrapped in the lower stage.

Consisdering many lower stages are kicked into a full 360 spin by the act of staging, I suppose a streamer loosely packed in the lower stage might be "spun loose" into the airstream just by the spin itself.

[kmf04040]

So my thought for recovering the booster is to have the engine extend from the mount by 1/4 inch. I'll have a length of kevlar string as a shock cord attached to the engine mount, then tied to the base of the motor along the string and secured with tape, and end with an 8 inch parachute. The parachute and excess cord will be tucked in between the airframe and the engine tube (the picture of the business end of the mount shows the gap I'll use). In theory, when the booster motor burns out and the sustainer ignites, the pressure will blow out the spent motor casing along with the parachute and cord. According to rocksim, an 8 inch parachute should slow the booster's descent to around 25 fps. The whole concept is similar to what kruland suggested in his post, but I've got to modify the idea slightly due to the fact that the motor mount is already epoxied into the airframe. I've already test-fitted the idea using the kits 14 inch parachute and know that there is room, so an 8 inch parachute should fit fine.

[kruland]

Hi everyone. I promised pics of what I did, and now I have them.

Here's the general construction. The motor tube is "as long as possible". I don't have the length off hand, but when the booster is assembled, the fore end of the motor tube butts against the motor tube of the sustainer, and the aft end of the motor tube is flush with the booster.

The centering rings are made from 1/8" ply though bass or balsa would work too. I didn't want to use paper because I thought they would wear out too quickly. The fore centering ring needs to be lower than you think in order to provide clearance for the transition.

The gap staging vent is fore of the centering ring so the excess pressure helps push the whole thing out the back.

I used a monster piece of mylar gift wrap for a streamer. It's simply taped to the motor tube. Honestly, I don't think any kind of recovery device is needed because my experience is it stages pretty low so just the destabilizing effect of separation is enough.

The kevlar thread is attached to the fore centering ring and between the transition & body tube.


To prepare for flight, the streamer is rolled around the motor tube. The kevlar is wrapped around as well. Make certain the kevlar does not get trapped between the fore ring and the body. Since there is still a long length of kevlar, as you insert the motor mount, you should continue to rotate the motor tube to take in the slack.



Here it is, ready to paint ... er, launch. When stacking the rocket and putting on the rod, you have to be careful to hold the motor tube in place. The centering rings are loose enough that it will slip out the back.

[Rocketbuilder]

Is there any way to use something like scotch tape to join the top of the booster motor tube with the protruding end of the sustainer motor? This would prevent the booster from separating before it lit the sustainer; it could only separate after the heat from the lit sustainer motor melted the tape.

[kruland]

Are you refering to my construction in particular? Yes, you can. Because the upper centering ring is so far down, the motor tube can actually be slid foreward enough to be completely visible. Although I have not taped them together, I do push it forward, engage the sustainer motor, then push the sustainer (and the booster motor tube) down to seat the sustainer on the transition. Make sense?

[Rocketbuilder]

Are you refering to my construction in particular? Yes, you can. Because the upper centering ring is so far down, the motor tube can actually be slid foreward enough to be completely visible. Although I have not taped them together, I do push it forward, engage the sustainer motor, then push the sustainer (and the booster motor tube) down to seat the sustainer on the transition. Make sense?

I'm not quite understanding your description here. If the booster motor tube needs to be pushed back to seat the sustainer on the transition, what stops the thrust produced by the booster motor from pushing the motor tube up and so pushing the sustainer up off the transition. I think I'm missing something.
From what you said earlier about the booster motor tube being loose enough to slip out on its own, it seems that the pressure from the booster motor at the time that staging should occur may just push the booster motor tube out, instead of lighting the sustainer.

[kruland]

Rocketbuilder. You are astute. Apparently when I go to work each day, I leave my head at home, and don't bother to think for 8 straight hours. That will teach me.

Ok - now that it's in front of me, here's the whole truth...

The front ring pushes tightly against the shoulder of the transition when the stages are engaged. I was completely wrong. However, if you want to tape them together this is what I would do...

I'd put a thrust ring in the fore end of the booster motor tube which is strategically placed so the sustainer motor would be tight against it when it's all put together. Then when the motor tube is out, I'd put the sustainer motor in the top and tape it in place. Then roll up the streamer and shock cord and insert the whole thing. Then place the motor in the sustainer. Don't forget the sustainer is friction fit.

One other bit to correct. The booster motor tube is short of the end of the booster so the motor nozzle is flush with the booster body when put together. This is of course personal preference. If you want it to be flush, make it 3/8" longer (than the measurement below)

Now for some actual measurements...


The booster motor tube is 11.5" long. The fore centering ring is 2 5/8" from the front of the motor tube. The aft centering ring is 1 3/8" from the back of the motor tube (though this dimension is not so critical.

Kevin

I'm not quite understanding your description here. If the booster motor tube needs to be pushed back to seat the sustainer on the transition, what stops the thrust produced by the booster motor from pushing the motor tube up and so pushing the sustainer up off the transition. I think I'm missing something.
From what you said earlier about the booster motor tube being loose enough to slip out on its own, it seems that the pressure from the booster motor at the time that staging should occur may just push the booster motor tube out, instead of lighting the sustainer.

[Rocketbuilder]

Rocketbuilder. You are astute. Apparently when I go to work each day, I leave my head at home, and don't bother to think for 8 straight hours. That will teach me.

Ok - now that it's in front of me, here's the whole truth...

The front ring pushes tightly against the shoulder of the transition when the stages are engaged. I was completely wrong. However, if you want to tape them together this is what I would do...

I'd put a thrust ring in the fore end of the booster motor tube which is strategically placed so the sustainer motor would be tight against it when it's all put together. Then when the motor tube is out, I'd put the sustainer motor in the top and tape it in place. Then roll up the streamer and shock cord and insert the whole thing. Then place the motor in the sustainer. Don't forget the sustainer is friction fit.

One other bit to correct. The booster motor tube is short of the end of the booster so the motor nozzle is flush with the booster body when put together. This is of course personal preference. If you want it to be flush, make it 3/8" longer (than the measurement below)

Now for some actual measurements...


The booster motor tube is 11.5" long. The fore centering ring is 2 5/8" from the front of the motor tube. The aft centering ring is 1 3/8" from the back of the motor tube (though this dimension is not so critical.

Kevin

Thanks, now I can visualize it much better. It sounds like that plan should work fine, so long as the sustainer motor friction fit is tight enough, the vent holes are sized properly, and you don't use too much tape to connect the sustainer motor to the booster motor tube.
How far is the sustainer motor inserted into the top of the booster motor tube? You don't want it to be too far, because then the nozzle (of the sustainer motor) will be too far away from the tape to melt it.
This is making me want to try gap-stagin again! My first scratch built rocket was a three-stager, with the third stage gap-staged from the second. Unfortunately it was only marginally stable on the second stage, and the third stage never ignited. The rocket has since been converted to fly on two stages (the third stage motor mount was removed and the whole stage was glued on to the second stage) and has flown successfully. It was definitely quite a learning experience for me!

[kruland]

Thanks, now I can visualize it much better. It sounds like that plan should work fine, so long as the sustainer motor friction fit is tight enough, the vent holes are sized properly, and you don't use too much tape to connect the sustainer motor to the booster motor tube.
How far is the sustainer motor inserted into the top of the booster motor tube? You don't want it to be too far, because then the nozzle (of the sustainer motor) will be too far away from the tape to melt it.
This is making me want to try gap-stagin again! My first scratch built rocket was a three-stager, with the third stage gap-staged from the second. Unfortunately it was only marginally stable on the second stage, and the third stage never ignited. The rocket has since been converted to fly on two stages (the third stage motor mount was removed and the whole stage was glued on to the second stage) and has flown successfully. It was definitely quite a learning experience for me!

The amount of sustainer motor in the booster tube depends on where you put the sustainer engine block. I constructed it with 5/16 overhang - I was probably shooting for 1/4 but missed To ensure correct placement, I'd put in one block, then after the glue dries, use a motor in the mount to push in the second one. My suspicion is 1/4" overhang would be too much to melt the tape quickly enough - but I have no experience with that at this time.

The vent hole is a single punch from a standard hole punch -what would that be about 3/16"? It seemed to be large enough to get ignition and eject the booster recovery.

I've noticed that the quest motor tubes tend to be really loose. It takes a bit of tape to get a good friction fit.

I've flown this configuration twice. Both times it staged successfully and I didn't attempt to tape the sustainer motor to the booster. The streamer did not fully unfurl but since I was boosting with B6-0, it was only 30' or so in the air when it staged. Unfortunately, on the second flight, I put a gumstick camera on the sustainer, and when it staged, there was not enough velocity to keep the whole thing upright. The sustainer turned into a cruise missile - shot down range, and unfortunately didn't get enough time to deply adequately. The sustainer tube took the brunt - folded almost completely up. I have since grafted on a new sustainer tube and plan to paint it before the next flight.

If you do attempt this, I have to tell you to sand down the fore shoulder of the transition quite a bit because it's molded very tightly.

[kmf04040]

I finally got my kevlar string to make my shock cord and now have finished my recovery system for the booster stage. Here are a couple of pictures with it installed and also deployed. When the sustainer ignites, the pressure ejects the booster motor, which in turn drags the 8" parachute out of the back with everything tied together by the kevlar string. I liked the idea of having the engine mount eject, but as I had already glued that in place, I decided to attempt to tie the motor casing into the shock cord and secure it with a wrap of 1/4" masking tape.

[foamy]

Let us know how it works out for you. Should be interesting.

[judo]

I'm working on the same issue with my Doorknob-2. It staged nicely on both flights but the sustainer igntion was not enough for rear-ejection of streamer.

When do you think you will fly again?

[kmf04040]

I launched my terrier-orion on its maiden flight today at the MMMSC launch on a D 12-0/B6-4 combo. The wind caused some weathercocking and the sustainer ignited after the rocket had started to level off. The booster recovered pretty much as expected. The motor and 'chute ejected out the back as expected. The trajectory of the sustainer carried it far downrange and the tube zippered when the 'chute deployed. Should be repairable.

[[POW]Eagle159]

NICE!

That is a cool recover idea for the booster, glad to hear it worked!