Heartily agreed!Never having built a Quest HL-20, I'm wondering--are its fins simply folded over at their leading edges to create "two-ply" cardstock fins (whose inner faces are glued together, I would presume)? Or does each fin have a spanwise spar (a length of dowel, maybe?) that is glued between the fin skins at the (swept-back, of course) mid-chord line? That would stiffen and strengthen the fins and give them a double-wedge airfoil shape. (Yet another--and structurally strong--option would be to give the fins a single-wedge airfoil shape, like the X-15's vertical stabilizer fin and ventral fin.) Also:

In your experience, how well (or poorly) does the Quest HL-20's "Northrop HL-10-like" fin *placement* affect its boost stability and glide ratio as compared to the X-24 Bug's boost stability and glide ratio? (Just looking at both designs, I would guess that the X-24 Bug might boost straighter but that the HL-20's two outer fin "winglets" might enhance its lift/drag ratio when gliding, as well as improve its roll stability during the glide, because those two fins' dihedral would "amplify" the dihedral effect of the cone fuselage's triangular cross-section.)Or in my case, having the energy and the model-building space! :-)Anything other than Baychimo or Marie Celeste... :-)

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Whoa... lotsa feedback.

I do prefer the HL-20-style fins. They are a little more aerodynamic as well as being stiffer.

The main difference is that the HL-20 fins are folded along the leading edge into a "V" shape with the tip glued closed but the root and trailing edge open. No spars or anything inside. I was just going to make a little strip of cardstock, fold it in half and glue it inside the leading edge of the X-24 fins.

The HL-20 goes pretty straight up. It wobbles somewhat, but I think that is due mostly to the launch lug being on the outside of the fuselage. As far as the glide... I don't know . Neither glide terrably well - Centuri stated a 2:1 glide ratio, and my HL-20 came reasonably close to that. (DANG! looks like I gotta build that thing after all - Atlantis)

One of the reasons I wanted to give the X-24 a try was because it is a really easy model the requires very little time (or money) to assemble (no sanding or painting).


PROPOSED NAMES FOR ENDEAVOUR: (from NASA web site)
Godspeed, Horizon, Nautilus, North Star, Pathfinder
Phoenix, Resolution, Trieste, Victoria, Victory, Blake,
Hokule'a, Eagle, Endurance, Griffin, Gulf Stream,
Investigator, Meteor, Polar Star, Rising Star, Royal Tern

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John Adams
"There is a lot of rocketry under 20ns"

Has anyone consider a Hybrid of both desings? Sounds interesting. I am extremely busy for rocketry for the next three weeks to take up this challenge, but maybe a fellow rocketeer can take up this challenge and report their findings... Just thinking...

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- Raúl
NAR #88644
SAM #230
EAC
CAT
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I'm going to do at least one X-24 with the "wedge fins" like the HL-20 uses. Depends on which one has the best hang time. Looks like it will be VERY Endeavour (built from spare parts).

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John Adams
"There is a lot of rocketry under 20ns"

A relative to the X-24 Bug?
http://www.cloudster.com/Sets&Vehic...tingBodyTop.htm

Innnnnteresting, Naoto...

UFO came out about 2 years before the X-24 appeared in the Centuri catalogue. I wonder if Mr Piester was/is a fan of the show...

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John Adams
"There is a lot of rocketry under 20ns"

Could have been though I think Larry Brown of the Centuri staff specifically developed their X-24 product if I recall correctly. but no telling what his actual influences may have been for the final design.


Earl

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Earl L. Cagle, Jr.
NAR# 29523
TRA# 962
SAM# 73
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Rocket-Brained Since 1970

Okay. I got a few minutes so I uploaded these

First pic: Columbia, Challenger, and Discovery showing longerons and balance weights

Second pic: Columbia - back end (yeah... I got the bulkhead off-center...:rolleyes

Attached Thumbnails

   

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John Adams
"There is a lot of rocketry under 20ns"

Yeah, I did that with my first one, too. It's sorta like a fat woman with her skirt on crooked, eh?

Doug

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YORF member #11

I have since learned to get everything lined up, put a drop of glue at each cover of the bulkhead, and set the model nose down in an empty cup to dry. THEN glue around the rest of the bulkhead.

Challenger and Discovery have much better alignment, and smoother exterior (Columbia has a pucker just in front of the bulkhead, but it's very slight - not enough to affect performance)

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John Adams
"There is a lot of rocketry under 20ns"