2-stager with APCP E28 booster

Ted Macklin and I have been talking complex staging using a composite booster for a couple years now, but I've been slow in getting stuff together for experimenting. Ted however has been working in the rocket shop to produce some interesting tests.

Saturday, we launched his 2-stager using an E28 reload as the booster staged to an E9 sustainer. As I understand, it was simply the E28-4, trimmed a hair - 1/16" - and gap-staged to the E9. Not sure if there was any fraction of BP ejection charge in the well, but the sustainer lit readily and continued on a flight mostly unseen by the three of us trying to track it.

While most of the sustainer flight was untrack=ed we somehow managed to recover it intact. The booster had a couple cracked fins, but that happens with ordinary BP staging, so it's to be expected - ie, it's acceptable. The sustainer was spotted near a creek bottom thanks to its fluorescent red/orange chute where my new son-in-law retrieved it.



This was our low-tech approach to getting around the lack of high-thrust BP boosters. I'm looking forward to trying this with a couple of my birds built just for this purpose but as yet unflown. I'm hopeful I'll get some rocket time in the near future to play with this some more.

Kudos to Ted for his diligence and success on this project. Salute!

Doug

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YORF member #11

So just hoping the ejection charge of the E28 would light the E9 while it was still pointing up?

kj

More than hoping. Ted had done some experimenting in a test stand environment, so there was a reasonable expectation of success. And, as I noted, the delay was trimmed to minimize the coast time before staging.

Doug

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YORF member #11

Well, not exactly. Here's what was done.

First off, the 4 second delay grain was drilled 1/16" (0.0635"), theoretically reducing the delay time to about 2 seconds while leaving enough bridge strength to prevent blowout and premature ignition of the black powder charge.

Next, only about 1/3 of the black powder charge was placed into the ejection cavity...just enough to cover the fireport hole. Then a length of homemade "quickmatch" was inserted into the ejection well and packed in with toilet tissue. Finally, a spent D12 casing was slipped over the forward bulkhead assembly with the clay nozzle pointing up and the quickmatch extending through it. There was no hard cofinement of the ejection charge and thus no "explosion" of same.

The black powder upper stage motor was then taped to the preceding assembly and the whole shebang inserted into the booster stage and a homemade engine retainer installed in place. This assembly, about 9.25" total length, was then pushed into the upper airframe.

I had performed swing tests of the full airframe and added about 1.7 ounces of nose weight to acheive aerodynamic stability. The upper stage was overstable. Total liftoff weight was about 13.5 ounces (383 grams). The body was BT60 tubing with a handmade balsa nose and an overall length of about 37".

Upon ignition this puppy screamed off the pad straight up and as predicted had about a two second delay. Upon ignition of the second stage, the upper airframe appeared to veer abruptly into a horizontal trajectory and displayed a good amount white smoke characteristic of black powder motors. In less than three seconds it was out of sight and we never observed chute deployment.

Doug and his new son-in-law recovered all parts after a extensive search at least one half mile downrange. After examining these parts I beleive the off line trajectory was caused by a less than ideal seperation which resulted from my failure to tape the spent D12 casing to the Aerotech E28 and only taping one half of the E9 to the spent D12 coulping. This resulted in an eccentric thrust vector and hence the goofy trajectory.

I did my homework on this project, but I have a lot more to do.

Thanks much to Doug and Eric who helped me in this experiment!. Doug, you made an awesome photo and I think we can get Eric hooked!

Back in the 1980's when Aerotech first appeared, they had a report that suggested you could use a piece of thermalite fuse from a APCP booster engine to a sustainer. I seem to remember Jerry Irvine recommended trying it with a modified Apache2/Tiger Streak using an E5-0/E5-8 combination for a F altitude record attempt. I did try this in one I cloned in one of my private launches. It worked, but I never found either the booster or the upper stage, despite a generous amount of red carpenter's chalk and a 6 ft red streamer. I barely saw the cloud of chalk and the streamer at ejection and the rocket very soon drifted out of sight at a high altitude. I did not repeat it again, and I think I still have one E5-0.

Here http://www.youtube.com/watch?v=9LHiUX30KQk is a video of a ground test I made in early January, 2013. Skip forward to 1:50 or so if you want to get to the action.

Also, some pics if they'll load.

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Nice to know we pharmacists can do something other than drugs!!!

Good job, Ted! Very informative.

Allen

Thanks Allen. But, I'm not the pharmacist. I just married one! She's the reason I'm still breathing!

Then, I'm glad she has kept you with us!

You just left out all of the details on what the staging mechanism was and said gap staging. That usually means two motors not touching with nothing in between them and the upper stage lit by a booster stage. That's not at all what Ted described.

Ted looks like he's created and tested a well thought out system, that probably wouldn't fly at one of our NAR section launches.

Yes, I've seen folks try just letting the ejection charge light the upper stage and even had one or two successful flights that way. I've also seen the flights that didn't stage using that method. That's why it probably wouldn't pass our RSOs here.

kj