The Estes "Uprated Alpha" . . . Upscales & Downscales, too !

[Ez2cDave]

The "Uprated Alpha" is not discussed very often . . . Its design is found in Estes TR-11 "Aerodynamic Drag of Model Rockets".

This thread will provide data, along with info on upscaled and downscaled versions of the Uprated Alpha.

Dave F.

 

[SolarYellow]

Calling @K'Tesh to post the .ork file.

It occurs to me that the Uprated Alpha is basically an Astron Sprint.

Further optimization:
Literature indicates that a taper of 4.5 degrees per side or an equivalent start-to-finish rate of reduction with a parabolic profile is aerodynamically optimum for a boat tail.

Would look at launching it lugless from a tower, using an Alpha III nose cone, and possibly using bass for the fins just for durability on the lake bed.

Playing with C18 and D20 motors, one might also sim to explore the effects of clipping the fins and/or shortening the body tube vs. adding nose weight to maintain acceptable stability margin.

It would probably be easiest to 3D print the fin can on a resin printer vs. setting up a jig to sand the airfoil profiles in the fins by hand.

Looking toward the natural PNC-80K upscale, I like fins profiled in balsa with a CNC router and glassed. Or maybe hot wired from foam if that even works this thin.

 

[K'Tesh]

Calling @K'Tesh to post the .ork file.

I have a pinched nerve in my right shoulder and it's giving my right hand pins and needle sensation. It's uncomfortable to sleep, nearly impossible to type. This sucks

 

[neil_w]

It occurs to me that the Uprated Alpha is basically an Astron Sprint.

I am confused why they used the name "Alpha" at all.

 

[Ez2cDave]

OK . . . UPSCALES and DOWNSCALES . . . DIAGRAM below CHART.



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[Ez2cDave]

I am confused why they used the name "Alpha" at all.

At that time that was designed, the Sprint did not yet exist ( written earlier, but not published, until 1970 ) . . . I suspect the the Uprated Alpha was the inspiration for the Sprint, released in 1970.

 

[SolarYellow]

I am confused why they used the name "Alpha" at all.

If you read that section of TR-11, it's a case study to apply the principles that have been under discussion leading up to that. They start with a common rocket design, the Alpha, and modify it to reduce drag for optimum performance. Basically, make more efficient fins and add a boat tail. The Alpha had not yet had time to become the icon it is now.

At that time that was designed, the Sprint did not yet exist ( written earlier, but not published, until 1970 ) . . . I suspect the the Uprated Alpha was the inspiration for the Sprint, released in 1970.

That would make a lot of sense.

 

[Ez2cDave]

Speaking of the Sprint, it used a longer, parabolic 4.375" BNC-50Y nose cone, as opposed to the 2.750" long, ogive BNC-50K, used on the Alpha.

The overall length of the Sprint was 13.8", while the Uprated Alpha was 12.0" in length. An interesting note is that the Sprint, even with larger fins and being 1.8" longer than the Uprated Alpha, came with a lead disk that had to be attached to the base of the nose cone for stability.

TR-11 makes no mention of requiring nose weight for stability . . . If you build one, Swing Test it, no matter what Open Rocket or Rocksim says !

 

[SolarYellow]

Random observations.

The Astron Sprint's fins were mounted to the body tube, where the Uprated Alpha fins are further back, partly on the boat tail and partly on the body tube, making the UA more stable. The UA fins are also thinner and, eyeballing it, have less area. I think for a production kit, it was probably a good call to go 3/32, as 1/16 balsa is likely to have some durability issues on a rocket that big.

More interesting question is whether to punch through the BT and mount the fins TTW to the MMT or just glue them to the outside of the boat tail?

The Astron Sprint graphics scanned at JimZ are clearly a precursor to today's Alpha III sticker, a detail I was not previously aware of. https://www.spacemodeling.org/jimz/estes/k-49.pdf So using an Alpha III nose cone for the Uprated Alpha and maybe doing something like it for graphics would "missing link" things together nicely.

The BOM that's the second panel in the JimZ PDF says the nose cone is a BNC-50X, 3 1/4-in long. That's really close to one of the cones in the Estes 3162 pack, so maybe now I have a use for that part. The balance of the extra length likely comes from the longer body tube and boat tail. In the yellow and white version without the Alpha III-style decals, the yellow of the nose cone is run down onto the body tube for a distance, which might be the source of any confusion about the length of the nose cone.

 

[GlenP]

The taper ratio for the uprated Alpha, tip chord to root chord, of 0.4 for the trapezoidal planform is a very close approximation to the lower drag of the elliptical planform fins that are used by the Sprint.

 

[SolarYellow]

And much easier to fabricate properly.

 

[GlenP]

Very true, for example, these are both high performance aircraft wing planforms.

 

[Ez2cDave]

The BOM that's the second panel in the JimZ PDF says the nose cone is a BNC-50X, 3 1/4-in long. That's really close to one of the cones in the Estes 3162 pack, so maybe now I have a use for that part. The balance of the extra length likely comes from the longer body tube and boat tail. In the yellow and white version without the Alpha III-style decals, the yellow of the nose cone is run down onto the body tube for a distance, which might be the source of any confusion about the length of the nose cone.

 

[SolarYellow]

Since I'm saving it, what year is that catalog page?

 

[bjphoenix]

The overall length of the Sprint was 13.8", while the Uprated Alpha was 12.0" in length. An interesting note is that the Sprint, even with larger fins and being 1.8" longer than the Uprated Alpha, came with a lead disk that had to be attached to the base of the nose cone for stability.

I built an upscale Sprint, upscaled to BT55 dimensions, with 18mm mount. I got a sim for the Goblin and modified it with the correct lengths, fin shape and tail cone. It is stable without any nose weight, which the way I understand stability relationships is to be expected. It flies pretty well on a B, I haven't launched it on a C yet.

 

[Ez2cDave]

Since I'm saving it, what year is that catalog page?

1977 . . . http://www.ninfinger.org/rockets/nostalgia/77estcat.html

http://www.ninfinger.org/rockets/rockets.html

 

[smstachwick]

Why has nobody tagged @BEC yet?

Unless we’re rather certain he has one already…

 

[BEC]

Why has nobody tagged @BEC yet?

Unless we’re rather certain he has one already…

No, I've not done much with Gerry Gregorek's TR-11 after showing it to Bill Simon and settling the whole @Raygun insistence that it DEFINED the Alpha because it had dimensions put to rest. If I wanted to build a Sprint, I would. This "Uprated Alpha" is an Alpha only in that it is using a 7.75 inch long BT-50 and an18mm motor mount.

Even the nose cone, as drawn, is more of an elliptical shape (like the injection molded Alpha III nose cone) rather than the sort of tangent ogive with an almost straight extension of the BNC-50K (and the first PNC-50KA).

It's funny — I got taken to task on the NAR discussion board by calling a Vapor essentially a Star Orbiter with a 24mm motor mount. They are much closer relatives (in my mind) than Dr. Gregorek's Uprated Alpha is to an Alpha. I do have a friend that build an Alpha with a boattail to increase its altitude performance. I don't recall if he thinned the fins. They were still Alpha-fin-shaped fins. It was successful if I remember right.

As long as I'm rambling on this: my many altimeter flights show me that an Alpha III, which is significantly heavier than even the current Alpha, still performs almost identically on most any motor from an A8-3 to a C12-6FJ. The thing is, the Alpha III's fins are MUCH thinner than 3/32 and they taper as they go outboard. I'm pretty sure that's why it works so well. I have no idea if performance equivalence with the existing Alpha was one of the design criteria Mike Dorffler used when he created the Alpha iII, but it sure works that way.

 

[Ez2cDave]

Some possible Motor Mount options for various Scales of the Uprated Alpha . . .

( Due to HIGH-ASPECT RATIO fins, it is STRONGLY RECOMMENDED to remain SUB-TRANSONIC . . . BELOW 900 ft/sec ) !

BT-20 diameter - 13mm motors

BT-50 diameter - 18mm motors

BT-55 diameter - 18mm / 24mm motors

BT-60 diameter - 18mm / 24mm / 29mm motors

2" diameter - 24mm / 29mm motors

BT-70 diameter - 24mm / 29mm / 3 X 18mm motors

2.5" diameter - 24mm / 29mm / 3 X 24mm motors ( with mods to MMT tube )

BT-80 diameter - 24mm / 29mm / 3 X 24mm motors ( with mods to MMT tube )

3" diameter - 29mm / 3 X 24mm / 4 X 24mm / 7 X 18mm motors

3.1" diameter - 29mm / 3 X 24mm / 4 X 24mm / 7 X 18mm / 38mm motors ( Plywood fins required )

BT-101 diameter - 29mm / 3 x 24mm / 4 X 24mm / 5 X 24mm / 6 X 24mm / 7 x 24mm / 2 x 29mm / 3 X 29mm / Combinations of 13mm - 29mm motors

4" diameter - 29mm / 3 X 29mm / 38mm / Combinations of 13mm - 38mm motors ( Plywood fins required on ALL )

NOTE : I edited the first post to include upscale data for LOC 4" tubing. ( Image & PDF file )

 

[Rex R]

Estes has a history of mix and match parts to make new rockets, call this one Tr-11. I would be Leary of promoting this one to heavy until someone runs the numbers and determines what it will take(if anything) to be stable.

 

[SolarYellow]

Long body tube, small motor, fairly generous fin area, lightweight fins. It would be irresponsible to fly it without simming it, but it's not likely to need much nose weight to be GTG. Use a balsa NC for historical fidelity and I'd not be surprised to see it hit 1 caliber with nothing extra. I say that on the basis of having done a lot of BT-50 OR work.

 

[Ez2cDave]

Estes has a history of mix and match parts to make new rockets, call this one Tr-11. I would be Leary of promoting this one to heavy until someone runs the numbers and determines what it will take(if anything) to be stable.

"Back in the day", that would have consisted of using the "Swing Test" . . .

 

[SolarYellow]

I generally use OR to trim my final stability factor (how much nose weight to add) to just what I want it to be, then confirm stability with the swing test as a sanity check/backup/belt-and-suspenders before launching.

 

[86mustang408w]

I'm doing a BT-80 body tube and Orange/Black paint scheme. Its not that great im horrible at upscaling. But this thread helps ty!!!

 

[plymouthpercussion]

During the pandemic with time on my hands, I came across a box of leftover Alpha 3 bulk parts. My stab at an uprated
Alpha, boat tail Alpha and the far right I'm going to fly on C motors.

 

[Long_Gone]

I'm contemplating visiting this research with todays technology...............

 

[BEC]

Since this popped back up I scanned back through it. Some additional thoughts, such as they are, came to mind:

As @SolarYellow notes in post #9 above, one of the decals on JimZ for the Sprint is a "precursor" to today's Alpha III stickers. Indeed it is the black waterslide decal that was part of the Alpha III kit (when the plastics were red and the body tube was white). The decals first appeared on the catalog livery in the 1973 catalog, two years after the Alpha III first appeared. The current orange peel-n-sticks carry the same part number.

And yes, the K-59 Sprint used the 50X nose cone which was introduced, I think, on the Constellation. That one's length, plus a body tube that was 1.75 inches longer than the Alpha's would account for a good chunk of the extra length.

It's kind of funny that I'm building models using a cardstock tail cone right now — one for B Eggloft Altitude and one for 1/2A Parachute Duration for NARAM-65. But I still have never built a Sprint.

 

[Long_Gone]

 

[Long_Gone]

Well I think I'll get in fusion 360 and tweak my mini alpha nose cone for lightness and create a smart altimeter payload bay in it and print them off x12 laser out some fins and get to it, order all the same 13mm motors from the same lot direct from Estes. I'll have to invest in a small weather measurement device........and get the GoPro ready

 

[Long_Gone]

Now that I think about this we need to think of this research project from a smart standpoint. I need to maximize the research resources. Instead of 3 rockets of each type, I could make just three rockets or four I meant. One in each category minus the spin fin one that is given. I believe barring loss or damage to a rocket the results can give good data with just 4 rockets. Mini ones of course. This should provide very good data for mini rockets and their performance as well as engine performance. Getting the same lot is good for a engine baseline but I also want to get a variety of lot numbers to assess the consistency of the production engines and the variance. This should be interesting, I'm not sure I want to publish that data seeing that I will be using Estes motors (13mm) and that may ruffle feathers.