Vintage Estes engines - age?

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Sooner Boomer

Well-Known Member
Joined
Mar 21, 2011
Messages
5,744
Reaction score
4,434
When I was visiting the rocketry guys at SWOSU over the weekend, I was shown a box of Estes motors that had been donated. In the box were several "diamond" boxes of Estes engines. Any idea how old these are/ Are they of any value to collectors? They are sealed in the original shrink wrap, and I didn't want to open them. Are these the packages with a length of nichrome wire you cut up to make your own igniters?

d-pak1.jpg
d-pak2.jpg
d-pak3.jpg
 
Mid 1970s. The A5-2s might be worth something to collectors as that motor has been OOP a long long time — except that one looks to be open. (This is speculation on my part as I do not collect motors.)

As for the A8-3s....unless they have been frozen/overheated in storage, just go fly 'em.

The motors in open diamond packs on hand have either "G" or "H" date codes, so 1976 or 1977. It's been awhile since I opened a sealed diamond pack, so I don't recall what igniters were included. I expect it was the nichrome with the flattened bits and the blue or brown pyrogen over those flattened places. Bare nichrome only would be older than that.
 
Mid 1970s. The A5-2s might be worth something to collectors as that motor has been OOP a long long time — except that one looks to be open. (This is speculation on my part as I do not collect motors.)

As for the A8-3s....unless they have been frozen/overheated in storage, just go fly 'em.

The motors in open diamond packs on hand have either "G" or "H" date codes, so 1976 or 1977. It's been awhile since I opened a sealed diamond pack, so I don't recall what igniters were included. I expect it was the nichrome with the flattened bits and the blue or brown pyrogen over those flattened places. Bare nichrome only would be older than that.
How did the A5s differer from the A8s? I’m guessing they shared a nozzle with the B6 or B8/B14 family?
 
Here's a picture of the ignitor(s) that were included with the diamond boxes. It's a piece of nichrome wire that has been flattened in two places (three in the uncut piece), and the flattened area then covered with pyrogen. The pyrogen is actually blue; it doesn't show up well in the picture. Also, it looks like the center portion is twisted in the picture. It's not. This is an artifact created by the (cell phone) camera.

old ignitor.jpg
 
I loved the Estes A5 motors. Used a lot of short ones - A5-2S - for gliders before the mini motors became avilable. I recently was able to get some tubed and boxed A5s along with some loose motors.

Chas
 
I loved the Estes A5 motors. Used a lot of short ones - A5-2S - for gliders before the mini motors became avilable. I recently was able to get some tubed and boxed A5s along with some loose motors.

Chas
What was the difference between the A5s and the modern A8s? I’m guessing they had the original thick casing?
 
What was the difference between the A5s and the modern A8s? I’m guessing they had the original thick casing?
I don't know if I've ever had any A5s.

Time-thrust curves for the A5 and A8 (at least at that time) were quite a bit different. This is from the 1969 catalog. This figure in later years was too blurry to read, even from a paper copy in hand. A5 in the inset, A8 in the main figure:

IMG_6128.JPG
 
I don't know if I've ever had any A5s.

Time-thrust curves for the A5 and A8 (at least at that time) were quite a bit different. This is from the 1969 catalog. This figure in later years was too blurry to read, even from a paper copy in hand. A5 in the inset, A8 in the main figure:

View attachment 544339
Interesting. That does indeed suggest a thicker casing material and a longer propellant grain.
 
That's a nice photo of the A5 thrust curve. I've generated a thrust curve using John Cooker's thrust tracer utility and I'll see about submitting it to thrust curve.

Is the A5 a 13mm motor or 18mm motor?
 
That's a nice photo of the A5 thrust curve. I've generated a thrust curve using John Cooker's thrust tracer utility and I'll see about submitting it to thrust curve.

Is the A5 a 13mm motor or 18mm motor?
My understanding is that the 13mm motors were developed later. Basically all the motors were 18mm diameter and the Series III was shortened to 45mm length instead of 70mm. This length later became the length of the 13mm mini motors that supplemented/replaced the lower end of the Series I line. 18mm 1/4As went the way of the dodo.
 
Last edited:
That's a nice photo of the A5 thrust curve. I've generated a thrust curve using John Cooker's thrust tracer utility and I'll see about submitting it to thrust curve.
Thanks. Just a quick iPhone picture of my 1969 catalog.

Is the A5 a 13mm motor or 18mm motor?
This predates 13mm motors. Apparently the A5 was available as both Series I (standard 18x70 mm) as well as the shorter (18x45mm) Series III. I've never even seen a picture of a Series III A5. One would give a Sprite quite the ride....
 
Thanks. Just a quick iPhone picture of my 1969 catalog.


This predates 13mm motors. Apparently the A5 was available as both Series I (standard 18x70 mm) as well as the shorter (18x45mm) Series III. I've never even seen a picture of a Series III A5. One would give a Sprite quite the ride....
I bet a scroll saw could get it down to size.
 
So John is willing to add the A5 to thrustcurve if anyone can find the original certification information. Anyone have any ideas or leads?
 
So John is willing to add the A5 to thrustcurve if anyone can find the original certification information. Anyone have any ideas or leads?
Maybe Estes will have it on file somewhere? So far they’ve never really disappointed in the customer service end. Not sure if they’ll be willing to help with purely archival/theoretical work but I’d say it’s worth a shot. Somebody at NAR headquarters may have it as well.

I’ll look around and see if Google yields anything.
 
The A5 and B4 used thicker casings than the A8/B6/C6, similar to those used for the older pre-metric engines. Presumably they were made on Mable I.
 
BEC: thank you very much for those nozzle shots.
Does it appear to you that the nozzle throats are more or less the same diameter.?
If so, then the A5 core wasn't as deep as the A8 core.

Looking at the catalog specs for A8 vs A5:

FMax: 48 oz vs 46 oz or 13.3 N vs 12.8N
FAvg: 21.33 oz vs 17.92 oz or 5.92N vs 4.98N

Burn time: 0.42 s vs 0.5s

There seems to be a discrepancy in the burn time from various Estes catalogs as to whether the burn time for the A8 was 0.32 or 0.42s.

Now compare to today's A8:
FMax : 9.73 N
FAvg: 3.18N
By: 0.73 s

Total impulse for the 2 older motors was 2.49Ns today's A8 2.32 Ns

The A8. specs are:
FMax: 23oz or 6.4N
FAvg: 0.8lb/12.8 oz or 3.56 N
BT: 0.9s
It: 3.1Ns

So this was actually a small B engine.

The A8,B6 and C6 motors all had/have(?) a nozzle throat of 0.107".
It's not know about the depth of core. One could assume they are mostly the same by looking at all 3 thrust-time curves.


Hth .
 
Last edited:
Maybe Estes will have it on file somewhere? So far they’ve never really disappointed in the customer service end. Not sure if they’ll be willing to help with purely archival/theoretical work but I’d say it’s worth a shot. Somebody at NAR headquarters may have it as well.

I’ll look around and see if Google yields anything.
I may have one. I have some S&T motor paperwork from the 62 to 64 timeframe. Of course, back then GHS WAS S&T. Currently at work, will find and post later.
 
BEC: thank you very much for those nozzle shots.
I didn't post 'em. @Sooner Boomer did. I could post an A.8 and B.8 nozzle shot now that I have one of each in my possession. Well, I had two A.8s but I flew one recently as I noted in another one of the old motors threads — flight data here: https://flightsketch.com/flights/3869/. That motor's date code was 7 5 67. For comparison, a contemporary A8-3 takes an Alpha III to ~180 feet carrying the same type of altimeter - FS Mini.

The A8. specs are:
FMax: 23oz or 6.4N
FAvg: 0.8lb/12.8 oz or 3.56 N
BT: 0.9s
It: 3.1Ns

So this was actually a small B engine.
It was an A at the time they were made, though today it would be a B (and it certainly performed like one). When the metric conversion happened, the total impulse ranges for 1/2A, A and B got rejiggered a bit. At the time A was 0.35 to 0.7 lb-s. But, you knew that, really.... :)
 
Last edited:
I may have one. I have some S&T motor paperwork from the 62 to 64 timeframe. Of course, back then GHS WAS S&T. Currently at work, will find and post later.

Ok, let me know what you find, and maybe we can get the data posted to thrustcurve.
 
I didn't post 'em. @Sooner Boomer did. I could post an A.8 and B.8 nozzle shot now that I have one of each in my possession. Well, I had two A.8s but I flew one recently as I noted in another one of the old motors threads — flight data here: https://flightsketch.com/flights/3869/. That motor's date code was 7 5 67. For comparison, a contemporary A8-3 takes an Alpha III to ~180 feet carrying the same type of altimeter - FS Mini.


It was an A at the time they were made, though today it would be a B (and it certainly performed like one). When the metric conversion happened, the total impulse ranges for 1/2A, A and B got rejiggered a bit. At the time A was 0.35 to 0.7 lb-s. But, you knew that, really.... :)
Oops. Thanks Sooner Boomer
 
It took me a while to find this TR-14 From May 1962 showing the 1st Estes Series 1 motors. I'm going to post more of these for the Estes Series 2 engines, Coaster F motors, Pyrodyne DEF motors, and Ill also post them all here an at Ye old Rocket Forum later tomorrow.
 

Attachments

  • TR14.pdf
    198.6 KB · Views: 1
Good advice in TR-14: "you should not point the nozzle towards your face."
 
Back
Top