Quantcast

The Coaster Dynasoar Centauri: an early mid power boost glider with R/C potential.

The Rocketry Forum

Help Support The Rocketry Forum:

tab28682

Well-Known Member
TRF Supporter
Joined
Jul 30, 2014
Messages
1,517
Reaction score
64
I ran across some information on the old Coaster Dynasoar Centauri boost glider model, produced by the Coaster Corp. in 1962. The design alluded to some possibility of it being flown RC on some of the old Coaster black powder motors, as an sentence in the corner of one of the old ads said: " You can radio control this one!". Evidently a couple of people tried over the years to make it work as an RC model, but could not as they evidently all pranged. Appears it had a boost CG issue.

Someone here on TRF did a successful free flight version at 2/3rds scale, for 18mm motors.

26" long, with a wingspan of about 15.5". Airframe is a 2" ID tube. Balsa nose cone

George G. has some history on the design, plus copies of the plans on one of his RC Rocketry pages, here: http://georgesrockets.com/GRP/GLIDERS/EarlyRC/FirstRC-preview.htm

Attached pics from George's pages.

The plans are a real draftsman's work of art. Seems a real shame that there is no documented evidence of one ever being flown successfully with R/C. An R/C build about 12 years ago petered out with no flight report over on YORF.

I think I am going to rearrange my production schedule so that after the Mizuno Shinryu is finished and do one or two of these, next. One for sure in Depron for an E6, hollow balsa nose cone (will have to turn one to match the drawing) and with the correct tube from BMS, a T204-34.

I might even do one with the flying surfaces in balsa, per the original, with 1/4" balsa wings and 3/16" balsa fins.

Would be fun to make one work with R/C, as envisioned, 58 years later.........
 

Attachments

Last edited:

aerostadt

Lifetime Supporter
TRF Lifetime Supporter
Joined
Oct 27, 2009
Messages
3,269
Reaction score
242
Location
Brigham City, UT
I remember seeing ad's for this model about 55 years ago. I had a few Coaster motors. The Coaster BP F-motors had quite a kick and reminded me of the Centuri BP F-motors (Min-Max motors?). I can't help but think that there extra fins in the design that could be removed to save weight. There is some more information in the TRF Gallery on this model.

 

tab28682

Well-Known Member
TRF Supporter
Joined
Jul 30, 2014
Messages
1,517
Reaction score
64
I remember seeing ad's for this model about 55 years ago. I had a few Coaster motors. The Coaster BP F-motors had quite a kick and reminded me of the Centuri BP F-motors (Min-Max motors?). I can't help but think that there extra fins in the design that could be removed to save weight. There is some more information in the TRF Gallery on this model.

Zero doubt that the original model has too many fins and other parts...:) The design appears flawed if they really expected it to glide after ejecting a spent 29mm motor casing. Balanced for stable boost with that motor weight, it would be insanely nose heavy after ejection.

However, I am going to honor this vintage design and make it look, externally, just like the original for historical reasons. I think a 24mm motor is plenty for this thing.

The gallery did not really have anything on the original design, other than a scan of the drawing. It had a scaled down FF version and the Semroc mini (non-gliding) version in there and that is about it. Lots more info on George’s page linked above.

Anyone know the specifications of the old Coaster BP motors? Might have to ask that over in propulsion. The plans mention 20, 30 and 40 pound thrust motors.
 
Last edited:

aerostadt

Lifetime Supporter
TRF Lifetime Supporter
Joined
Oct 27, 2009
Messages
3,269
Reaction score
242
Location
Brigham City, UT
Rocketguy101 reported that the Centuri Mini-Max F-motor was about 7.75" long on this TRF thread.
Rocket Reviews reports that the Mini-Max F-motor was derived from the Coaster motor, which I find as believable because I had both and they were very similar.
 

Ez2cDave

Well-Known Member
TRF Supporter
Joined
Jan 18, 2009
Messages
4,100
Reaction score
1,161
Rocketguy101 reported that the Centuri Mini-Max F-motor was about 7.75" long on this TRF thread.
Rocket Reviews reports that the Mini-Max F-motor was derived from the Coaster motor, which I find as believable because I had both and they were very similar.

Some pics . . .

Dave F.

1a.jpg




Cstr_MMX_EJ_SSRS_3.jpg
 

tab28682

Well-Known Member
TRF Supporter
Joined
Jul 30, 2014
Messages
1,517
Reaction score
64
Thanks for the engine pics.

Ordered the Centuri ST-20 equivalent tubing today.That will give me all needed parts except for the nose cone, which will have to be turned from balsa, or perhaps printed.

Unlikely to start one of these before retiring at the end of the month, but progress should be rapids after that.
 

Ez2cDave

Well-Known Member
TRF Supporter
Joined
Jan 18, 2009
Messages
4,100
Reaction score
1,161
show the cores and ends.....with a ruler
Not my motors, but this is an F55 Mini-Max nozzle.

NOTE : There was also an F97 Mini-Max motor.

Dave F.

minimaxenozzle.jpg
 

tab28682

Well-Known Member
TRF Supporter
Joined
Jul 30, 2014
Messages
1,517
Reaction score
64
High impulse F motors like the Coasters mentioned seems like maximum overkill for a boost glider of this size. But, that was what they had to work with, I guess. The big heavy Fs are just not compatible with the CG needed for this thing to boost and then to glide, as a free flight. Would have had to have a pop pod with serious nose weight exiting the model at ejection to have a chance.

My Depron version will do well on an E6. I would expect the balsa version that I am also planning will do very well on an E15 or thereabouts.

George G. did some very intelligent analysis of this vintage design over on YORF. See post 150 on this thread.

 

burkefj

Well-Known Member
TRF Supporter
Joined
Jan 27, 2009
Messages
3,256
Reaction score
682
Tom, the estes PS-II 2" tubing is a press fit into the ST-20 tubing from BMS, what I did for my upscale scissor wing transport was to cut a piece of PS-II tubing to the length of the shoulder of the PS-II 2" nose cone, glue it onto the shoulder of that cone, and cut a small piece of ST-20 tubing 1/4" long to glue onto the front of that PS-II piece to make a "stop" for the cone to not slide into the tube, it leaves a very small step at the tubing/cone interface but the parts are only a few dollars from estes and they are strong and lightweight, you won't have to turn anything and the PS-II tubing into the ST-20 tubing fits perfect. It won't be scale to the original but it will work in a pinch, or if you can find a balsa cone to fit the PS-II tubing you can do the same thing.

Frank


Thanks for the engine pics.

Ordered the Centuri ST-20 equivalent tubing today.That will give me all needed parts except for the nose cone, which will have to be turned from balsa, or perhaps printed.

Unlikely to start one of these before retiring at the end of the month, but progress should be rapids after that.
 

tab28682

Well-Known Member
TRF Supporter
Joined
Jul 30, 2014
Messages
1,517
Reaction score
64
Tom, the estes PS-II 2" tubing is a press fit into the ST-20 tubing from BMS, what I did for my upscale scissor wing transport was to cut a piece of PS-II tubing to the length of the shoulder of the PS-II 2" nose cone, glue it onto the shoulder of that cone, and cut a small piece of ST-20 tubing 1/4" long to glue onto the front of that PS-II piece to make a "stop" for the cone to not slide into the tube, it leaves a very small step at the tubing/cone interface but the parts are only a few dollars from estes and they are strong and lightweight, you won't have to turn anything and the PS-II tubing into the ST-20 tubing fits perfect. It won't be scale to the original but it will work in a pinch, or if you can find a balsa cone to fit the PS-II tubing you can do the same thing.

Frank
Hmm. good idea and I might go that route to avoid turning a balsa nose cone. Good to have options.
 

georgegassaway

Lifetime Supporter
TRF Lifetime Supporter
Joined
Jan 18, 2009
Messages
4,625
Reaction score
487
As for the original Coaster kit, my conclusion is that there is no evidence that anybody EVER tried to fly it by R/C. What I wrote on my website:

"There were some references to flying it by R/C, but curiously no reports of one ever flying successfully with R/C. Perhaps one of the things that supported this over the years was an advertisement in American Modeler Magazine, from August 1962. The upper right side of the ad said "You Can Radio Control This One!". Well, maybe somebody could have, but it seems nobody at Coaster ever did. The actual plans do NOT show how to convert it for R/C."

Take note that R/C gear was incredibly heavy in 1962. Servos? Forget it, they were "bricks", as were the receivers and batteries needed. The only theoretical R/C that could have been tried was rudder-only Pulse R/C, which indeed was the kind of R/C used in the earliest recorded actual R/C boost gliders in the late 1960's. The earliest known successful one was by Doug Malewicki in 1967, using a decidedly "normal" looking hand-launch style of glider with a front engine pop-pod added.


I look upon the Centauri Dyna-soar as a pretty crude early attempt at a "high power" boost glider, as in E to F power in those days. Heck, I didn't even find a record of anyone flying one successfully at all as non-R/C in those days. You would expect a kit to at least have worked for the manufacturer when they tested it. Assuming they tested it. Which, I dunno, might not be a great assumption.

Personally, I have zero interest in ever building one. I would like to see video if someone does manage to get it to fly successfully, as in boost up and glide down. And I am not even talking R/C, I mean free-flight.
 

tab28682

Well-Known Member
TRF Supporter
Joined
Jul 30, 2014
Messages
1,517
Reaction score
64
I agree the anecdotal reports on an attempt or or two flying it by RC are suspect, due to the near impossibility of radio controlling an elevon controlled model with contemporary equipment. Barely possible that some one might have tried to add pulse rudder to attempt to steer it, keeping the elevons actuated at ejection. Who knows?

As you likely know, someone posted here on TRF a 2/3 size downscale free flight that is as reported to fly well. Nothing wrong with the basic aerodynamics of the design.

Seems logical that a full size FF version would work, but not as is, using a heavy F motor. Too much of a CG issue. It could be made to work with a heavy pop pod, but that is a major change to to original design. Also, that thing would get hard to see at possible full F altitudes.

Despite the designed in flaws, it it (to me) a very interesting early (in fact, the first, apparently) mid power boost glider design that envisioned the kind of RC rocketry we are doing now. The RC reference in the ad and in the plans was much more concept and marketing hype than reality. I think it will be fun to make one work with in a modern way. I really like the vintage styling of the thing.

It was an overreach, too much, a number of years too soon, but they got the concept right.
 
Last edited:
Top