Thanks gents, appreciate all the kind words. Now on to...

Lessons learned from first flight.

What worked:

The aerodynamics and structure are sound. Thrust line angles are precisely correct for the motors used (this was my biggest concern). Separation dynamics were very good. The C.G for the stack and the Orbiter model was right on the money. Trim settings and control deflections for the glider worked well, although a little more nose up trim on boost will be used next flight. The parachute seems to be sized correctly for the booster weight and the external risers took the deployment loads just fine (my next biggest concern).

What didn’t work:

The hold back fitting didn’t hold the model back when one motor failed to light. Apparently, the chuff of the igniters alone was enough to burn through the strings. Gonna have to experiment with this a bit. Possibly move the model further up the rail. Fortunately, it hung up on the launch rail and wasn’t damaged too badly. (2 minutes of sanding the tip fins fixed that... I had the clearance a little too tight. )

The parachute deployed fully at high speed without failing but the shock cord snagged on the cutouts for the external risers (it has a three point harness on the outside of the body tube). Consequently, the three point harness didn’t do its thing and the booster came down nose first instead of horizontal. This has already been fixed for the next flight. I did some minor re-rigging and that solved the problem.

What’s getting changed:

I’m doubling the motor retention hooks so they can be safety wired. There was some evidence that the booster motor could kick itself out without firing the chute piston out (a very, very bad thing).

Motor selection and delays:

Motors for the first flight were an E15-4W and a D7-RCT. The next test flight will be with an E15-3W and an E7-RCT. This will give me true boost/sustainer 1 ½ staging. The sustainer will finish burning approximately 1.0 to 0.5 seconds before the ejection charge on the booster fires. This should provide separation just before apogee (instead of 2.5 very long seconds after).

Preliminary Specifications:

Body tube dia: 2.6 inches
Length 47 ½ inches
Span 17 ½ inches
Combined Empty Weight : 26.17 oz
Recommended Motors : still testing


Regards,

DJ Miller

(Blackshire - I haven't gotten any calls from Lockheed/Martin about a RLV yet ... I'll let ya know.)

Great post-flight analysis!

__________________
Tim Wilson

For aesthetic and utility reasons, I have always preferred the early 1970s Phase B Space Shuttle study design proposals (particularly the ones that used Dr. Max Faget's straight-winged, low-crossrange orbiter designs) because those two-stage, fully-reusable winged booster/orbiter vehicles were true spaceships. The BlackStar TSTO design is also a true spaceship.

The new Shuttle-derived, 5-segment Ares I solid propellant first stage motor (and perhaps the "stock" 4-segment Space Shuttle Solid Rocket Booster motor) could be fitted with wings, tail surfaces, avionics, landing gear, and a flyback turbofan propulsion system to convert the large motor into an automated flyback booster, which would be much easier to refurbish and reload than the parachute-lowered, ocean-recovered Solid Rocket Boosters and Ares I first stages. Such flyback boosters could carry both reusable winged orbiters and (for orbiting heavier payloads) expendable upper stages.

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

It all comes down to mass fraction to orbit, doesn't it?.

Our governments unwillingness to fund projects that require huge financial outlays initially, but manageable funding over time lead to the Space Shuttle. I've seen the early wind tunnel models of alternative designs (like those you mentioned) and in the long run some of them might have been cheaper.

I respectfully disagree on one point. Large payloads (and I mean really large ) will, for the foreseeable future, require an expendable booster. You are dealing with two separate and distinct classes of vehicles here. What I have tried to do with my BlackStar model is merely present a tantalizing hypothetical solution to the two stage to orbit problem .

Now, back to the build log...

Flew it again last Saturday and nearly lost it. Got an early separation (been messing with the delays on an E15), lost orientation on the glider at low altitude and flew it right into the ground. Fortunately she's a rugged little ship and the ground was soft. No damage, its ready to fly again.

However, it needs MORE POWER! In light winds it's manageable, but for the next series of test flights I'm looking at an F20 or even an F32 in the booster . In order to do that I will have to completely redesign the "Mouse Trap". Above 4.5 G's and 90mph it needs a positive locking mechanism to hold the stack together. I can't take the chance of it coming apart during the coast phase due to air loads. In addition to that. I have to build a new motor mount that can support 29mm motors (a contingency I already planned for and have all the parts stockpiled ... not a big deal).

The good news...

Doubling the motor retention hooks and safety wiring them together worked flawlessly. I've also improved my parachute and rigging technique (clean deployment, even at low altitude). Heavy duty burn strings on the hold back fitting and an additional 1 3/4 inch offset from the nozzles looks like it may solve the "chuffing" problem.

Oh, I have attached my RockSim file. Please do not try and build anything from it. Also, make note that the Cd, Cg and reference area have all been overridden to reflect what has been measured or observed from the first two flights (don't mess with them).

Regards,

DJ Miller
Formerly: Captain of Marines / Naval Aviator

Next week: Vacation... taking my father to the Marine Corps Reserve Birthday Banquet. Two generations of Marines in one room on the same day... standby for heavy rolls and high seas. Oooh-Rah. Semper Fi !

Attached Files

BlackStar_Block1.rkt (91.4 KB, 62 views)

To this post, or some earlier post?

kj

You're disagreeing with a point I never made. I never said that such a vehicle would be a heavy-lift launch vehicle, just that it could orbit more using an expendable upper stage than a reusable winged orbiter. For orbiting truly massive payloads (Saturn V-size and more), a huge expendable vehicle like Aerojet's solid propellant "260 Space Booster" (see the Estes model plan here: http://www.spacemodeling.org/JimZ/eirp_36.htm ) or a liquid propellant equivalent similar to the old Nova designs would be the way to go.

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

OOps, added it to post #44.

DJ

BlackShire

I think I misread your post and interpreted "heavier" as "heavy". Actually we are in complete agreement. Sorry for the misunderstanding.


These are the sorts of things that came to my mind when you said "heavier".

Regards,

DJ

No problem. I think the reusable launch vehicle problem has a psychological element as well as the engineering challenges--it is a seemingly impassable barrier in many engineers' minds. If a sub-scale, suborbital sounding rocket version of the BlackStar vehicle (say, 500 pounds of payload to 400 miles and back) were built and then flown several times in two months, it would break that psychological "block" that "it can't be done."

__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR

Give me a grant for 28.3 million dollars and some students from Cal Poly (my old school) and I'd be happy to try. It would seem from their work on the StarBooster project that they have what it takes to surmount "a seemingly impassable barrier".

Now back to the build... next post, a better "Mouse Trap" and bigger motors.

Regards

FlyBack