Supersonic MODEL Rocket?

[dedleytedley]

I'm wondering if it's possible with the new definition of a model rocket to achieve mach 1 or faster without re-kitting the rocket while staying within the motor restrictions?
Does anyone know of a rocket that's already done it?
I'm not sure, do three AT F-21's exceed the limits? Ted

 

[Luv2launch]

If you build it good enough the Apogee Aspire on a G77 can supposedly break mach.
https://www.apogeerockets.com/aspire_rocket.asp

 

[jbuscaglia]

It was done 25 years or so ago (early 1980's) and was written up in an issue of Model Rocketeer, which was the name of the NAR's magazine at the time. IIRC, it was done by Chuck Mund using a single F motor. I'm at work, so I can't cite the issue, but maybe someone else here can give you that info.

 

[Initiator001]

In the Rocketry Forum Archive, there is a thread titled "World Speed Record" (Or something like that ) that has a comment I posted with information about the Speed Trial flown out in the Las Vegas desert nearly 20 years ago.

You CAN do Mach 1 with an AeroTech D21 motor and the properly designed rocket.

 

[MarkII]

I think that it is possible but difficult to do. One of the problems is verifying that the rocket actually went Mach. I can't cite the details, but basically something that is the size of a model rocket doesn't create a very big shock wave, so verifying the supersonic speed by listening for the sonic boom will be troublesome. There won't be much of one, and it may not even reach the ground. If it does, you will need to have observers standing in just the right places in order for them to be able to detect it.

MarkII

 

[MarkH]

There is a thread on rocketry planet where Adrian A. built an F altitude min dia. rocket. If you follow the link at the bottom of the first page there are velocity plots that show it going ~ 500 mph on an F10. With a similar build you could proabably go mach on a high thrust motor like an AT G76 RMS, or the G80T which is the highest total impulse model rocket motor available.https://www.rocketryplanet.com/forums/showthread.php?t=4081&page=1

 

[MarkII]

Is there any way to tell from a simulation just when or if a rocket will strip its fins or shred? :confused2:

MarkII

 

[stanbajacal]

The Mach Buster from Rocket Vision did it years ago. I was never able to recover this tiny beast, because when you used the Rocket Vision recommended motors once it left the pad that is the last time you see it.
You can read the build reveiw over at EMRR by Moira Jean Whitlock.

 

[MarkII]

FSI's ****** Dart, when used with the RX-1 Thruster (basically, a naked F100-0 booster used as a first stage) was supposed to be "supersonic-capable" but I don't know if anyone actually ever achieved Mach with one. There is apparently also some disagreement over whether the Mach Buster ever actually did that, too. I did come across some technical article on the web awhile back that disputed that claim; you can probably find it with a Google search.

MarkII

 

[MarkH]

Is there any way to tell from a simulation just when or if a rocket will strip its fins or shred? :confused2:

MarkII

I'm guessing but I would assume the transition to mach would be the most stressful point. I think you would need something stronger than balsa fins to go supersonic.

 

[MaxQ]

FSI's ****** Dart, when used with the RX-1 Thruster (basically, a naked F100-0 booster used as a first stage) was supposed to be "supersonic-capable" but I don't know if anyone actually ever achieved Mach with one. There is apparently also some disagreement over whether the Mach Buster ever actually did that, too. I did come across some technical article on the web awhile back that disputed that claim; you can probably find it with a Google search.

MarkII

I have the old FSI catalog...(see the rocket in picture...lower left corner).

I came real close to buying that Mach 1 system...filled out the order form but never sent it.
Going Mach and proving you did in those days was a challenge.

I did build and fly the RocketVision Mach Buster and it was a real hoot.
Never would have seen any trace of it after pushing the button - had it not had been crammed full of red tracking powder.....
Whether it went Mach - I can't say...



https://www.oldrocketplans.com/fsi/fsiMRK-XVII/MRK-17_Dart.pdf

https://www.ninfinger.org/rockets/catalogs/fsi90/90fsi8.html

 

[georgegassaway]

I never fully bought the claim that the FSI ****** could really go supersonic. Note I am not saying I think the claim was 100% bogus, but I tend to think it is a lot more likely be untrue than true.

If a person could get hold of some truly accurate engine data for the F100 and D20, not just the FSI claimed thrust curves and N-sec, but REAL data, and also account for the real-world engine masses and so forth, it would be interesting to run the whole ****** system in Rocksim and see if it was likely it really could do it. Keep in mind that the F100 was only about 50 n-sec, but the actual N-Sec may have been less than that (The "E5" was supposed to be 22 N-sec but by sometime in the early 1980's the NAR certified the E5 as a "D", at something like 17, or 18, or just maybe 19 N-sec. That was symptomatic of some other motor claims as well, I do not think the real performance delivered by the F7 or F100 was over 45 N-sec). Also keep in mind those were BP motors, and their casings were cardboard, pretty darned heavy.

Since the D20 was a friction-fit inside of the F100, I think that most likely the "Sonic Pop" some claimed to hear, was literally the D20 POP-ing out of the F100 at staging. Or even just hearing the D20 itself when it staged. Several others speculated those two as well.

Edit - I am not totally sure if the booster was an F100, or an E60. If an E60, even worse.

The composite Enerjet engines of the early to mid 1970's, their time-thrust curve was very bad for rockets overall, with relatively low thrust at liftoff, and progressively stronger thrust as they burned. But for a rocket intended to go supersonic, that would be the kind of curve you'd want - more and more thrust as the drag built up more and more from the increasing velocity. I think someone claimed to have gone supersonic using an Enerjet F67, which might have been possible (and it was close to a full F motor) but I do not think they had a way to prove it.

It would ALSO be interesting to run a sim of an F67 inside of a minimal 30mm rocket to see how that would have compared against the FSI ****** system or even today's "F" class motors regarding Supersonic flight.

- George Gassaway

 

[MarkII]

The information that I have on the ****** Dart pretty much agrees with what you said, except that people who have actual examples of them confirm that the RX-1 Thruster was indeed an F100-0 booster motor. In the meager literature on it that is available online, FSI stops short of stating that the Dart-RX-1 Thruster combination will go supersonic, only that it "has supersonic potential." In the kit plans there is a general description of transonic and supersonic flight, and the claim that the Dart had exceeded the speed of sound in flight tests. They reported that the sonic booms sounded like the report from a small caliber rifle, and that they were only audible where the edges of the cone of sound that radiates from the tip of the nose cone intersect the ground. They also said that the supersonic portion of the flight was only momentary at an altitude of between 1200 and 1500 feet. Finally, they add that because the exact speed of sound depends on such factors as the elevation above sea level, the local air pressure and air temperature and other factors, the ****** Dart "cannot be guaranteed to exceed the speed of sound under all conditions." This should all be obvious, anyway. From what I have read, it is not all that easy to get even a high power rocket to go supersonic.

BTW, I just finished building a clone of the Dart last week. It has an 18mm mount in the sustainer. I have created the needed parts to construct a faux RX-1 Thruster (that will actually be a reusable booster stage powered by D12-0 motors), but I haven't assembled it yet. Obviously my clone won't "have supersonic potential" but, in accordance with the kit instructions, I left a launch lug off of the sustainer. If I want to fly it in single stage configuration, I will need to launch it from a tower or a piston, or use a fly-away lug. When Quest releases its 28mm black powder F motor, I will probably be able to use it as a modern analog of the RX-1 Thruster. It may even be more powerful than FSI's motor was.

In EMRR's RockSim Library there is an archive containing motor files for most of FSI's motors, including the never-released G60. The library also contains a RockSim file of the ****** Dart/RX-1 Thruster combination that was created by Steve Naquin. A sim of a flight (from my location) on a F100-0/D20-7 motor combination yields a maximum velocity of 1098.95 fps and a maximum altitude of 3401 feet. That max velocity just reaches into the supersonic range, I believe. But of course, this is only a simulation.

MarkII

 

[Rocketjunkie]

You CAN do Mach 1 with an AeroTech D21 motor and the properly designed rocket.

A 13mm D40 in a lightweight rocket will do 1000 mph. I've never gotten one back and I've never heard the sonic boom.

View attachment cb13.rkt

 

[shreadvector]

I'm wondering if it's possible with the new definition of a model rocket to achieve mach 1 or faster without re-kitting the rocket while staying within the motor restrictions?
Does anyone know of a rocket that's already done it?
I'm not sure, do three AT F-21's exceed the limits? Ted

The limits you are unsure of are explained very simply in the limits document listed in the sticky thread that contains the wisdom of the ages.

https://www.rocketryforum.com/showthread.php?t=539

https://www.doug79.com/stuff/HPR_metric9c.pdf

 

[rocket999]

A 13mm D40 in a lightweight rocket will do 1000 mph. I've never gotten one back and I've never heard the sonic boom.

:jaw::eyepop::y:

I need to try that. Green monkey aerospace? What propellant?

"BANG!" and it would be gone...:bangbang:

 

[bobkrech]

There are 2 criteria required for a rocket to reach mach 1.

1.) The rocket motor must develop enough thrust to overcome the drag forces at mach 1.

Drag = 0.5 * Cd * rho * A * V^2

where Cd is the drag coefficient at mach 1, rho is the density of air which at sea level is ~1.3 kg/m^3, A is the cross-sectional area of the rocket, and V is the velocity of the rocket at mach 1 = 340.3 m/s.

Below is the calculated thrust required for a minimum diameter rocket with a given motor size to reach mach 1 assuming a sea level air density, 15 C air temperature and Cd = 1.

10 mm ==> 7.6 N
13 mm ==> 11.6 N
18 mm ==> 20.5 N
24 mm ==> 37.2 N
29 mm ==> 55.5 N

If you know your altitude, the air temperature, and the actual Cd of your rocket at mach 1 you can get a more exact value, however this simple number can be used to throw out motors that simply don't have the thrust to make the claim.

2.) Besides have enough thrust to overcome the drag forces at mach 1, the motor must have sufficient total impulse to accelerate from 0 to 340.3 m/s. This requires a rather complicated multi-parameter fit. But there are some rules thumb form minimum diameter rockets based on the above minimum thrust criteria.

29 mm rockets - Average thrust must exceed 56 N and T/W must exceed 120 to stay below 160 NS

24 mm rockets - Average thrust must exceed 38 N and T/W must exceed 80 to stay below 160 NS, T/W must exceed 160 to stay below 80 NS, T/W must exceed 320 to stay below 40 NS

18 mm rockets - Average thrust must exceed 21 N and T/W must exceed 44 to stay below 160 NS, T/W must exceed 88 to stay below 80 NS, T/W must exceed 176 to stay below 40 NS, T/W must exceed 352 to stay below 20 NS

13 mm rockets - Average thrust must exceed 12 N and T/W must exceed 50 to stay below 80 NS, T/W must exceed 100 to stay below 40 NS, T/W must exceed 200 to stay below 20 NS

10 mm rockets - Average thrust must exceed 8 N and T/W must exceed 65 to stay below 40 NS, T/W must exceed 130 to stay below 20 NS, T/W must exceed 260 to stay below 10 NS

Again these numbers assume sea-level altitude, temperature = 15 C and Cd = 1. If the altitude is higher, or the Cd is lower, the average thrust and total impulse numbers are less.

But you can't beat the laws of Physics.

Bob

 

[bobkrech]

I'm wondering if it's possible with the new definition of a model rocket to achieve mach 1 or faster without re-kitting the rocket while staying within the motor restrictions?
Does anyone know of a rocket that's already done it?
I'm not sure, do three AT F-21's exceed the limits? Ted

The simple answer is that an F-21 engine does not have the power to exceed mach 1.

See above.

Bob

 

[shreadvector]

The simple answer is that an F-21 engine does not have the power to exceed mach 1.

See above.

Bob

This one was the motor of choice for sonic attempts for many years:

https://www.thrustcurve.org/motorsearch.jsp?id=91

https://nar.org/SandT/pdf/Aerotech/G55.pdf

Not currently certified, not currently in production.

 

[jadebox]

They reported that the sonic booms sounded like the report from a small caliber rifle, and that they were only audible where the edges of the cone of sound that radiates from the tip of the nose cone intersect the ground.

Which is, of course, a bogus claim because the shock wave wouldn't intersect the ground.

-- Roger

 

[shreadvector]

Does the F100-0 simulation file actually represent the real F100-0?

By that I mean:

1) What alleged total-impulse and thrust curve is in the sim file?

2) Does it correctly include the delay time? YES, I said delay time. F100-0 motors had a delay and an ejection charge with no cardboard cap on top. They had a very short delay (1 or 2 seconds) so that the motor would not blow through during burn sinc ethey were operating on the hairy edge of the design limits. The delay helped keep it intact and the ejection charge was the granular BP they normally used but it had a clear laquer covering the top so that it could blow upward and ignite an upper stage.

The information that I have on the ****** Dart pretty much agrees with what you said, except that people who have actual examples of them confirm that the RX-1 Thruster was indeed an F100-0 booster motor. In the meager literature on it that is available online, FSI stops short of stating that the Dart-RX-1 Thruster combination will go supersonic, only that it "has supersonic potential." In the kit plans there is a general description of transonic and supersonic flight, and the claim that the Dart had exceeded the speed of sound in flight tests. They reported that the sonic booms sounded like the report from a small caliber rifle, and that they were only audible where the edges of the cone of sound that radiates from the tip of the nose cone intersect the ground. They also said that the supersonic portion of the flight was only momentary at an altitude of between 1200 and 1500 feet. Finally, they add that because the exact speed of sound depends on such factors as the elevation above sea level, the local air pressure and air temperature and other factors, the ****** Dart "cannot be guaranteed to exceed the speed of sound under all conditions." This should all be obvious, anyway. From what I have read, it is not all that easy to get even a high power rocket to go supersonic.

BTW, I just finished building a clone of the Dart last week. It has an 18mm mount in the sustainer. I have created the needed parts to construct a faux RX-1 Thruster (that will actually be a reusable booster stage powered by D12-0 motors), but I haven't assembled it yet. Obviously my clone won't "have supersonic potential" but, in accordance with the kit instructions, I left a launch lug off of the sustainer. If I want to fly it in single stage configuration, I will need to launch it from a tower or a piston, or use a fly-away lug. When Quest releases its 28mm black powder F motor, I will probably be able to use it as a modern analog of the RX-1 Thruster. It may even be more powerful than FSI's motor was.

In EMRR's RockSim Library there is an archive containing motor files for most of FSI's motors, including the never-released G60. The library also contains a RockSim file of the ****** Dart/RX-1 Thruster combination that was created by Steve Naquin. A sim of a flight (from my location) on a F100-0/D20-7 motor combination yields a maximum velocity of 1098.95 fps and a maximum altitude of 3401 feet. That max velocity just reaches into the supersonic range, I believe. But of course, this is only a simulation.

MarkII

 

[dedleytedley]

Thank you to everyone for your responses. What I intend to build is a 3x24mm cluster in an unusual? design. It's based on a BT-80 airframe 34" long with an Estes 80BB NC. The NC has a central 28mm aperture with a 25mm I.D. tube to it and protruding from the base of the NC. A 24mm tube mounted centrally with 3 CR's through the BT mates with it and continues all the way to the motor mount. There it reduces to 16mm and provides an air passage to the area below the recessed MMT. The fins will be 1/8 TTW plywood elliptical high aspect ratio 5" long, 1.7" span. The rocket is basically a flying thick-walled tube with elliptical fins. The space between the tubes will house the parachutes and conduct the ejection gases forward. I'm aware of the drag penalties with the increased surface area from the central tube.
I plan to launch the rocket inside a six foot length of 6" sonotube with a tough paper cone on the rocket base to make it a piston launcher that will drag separate after exiting the launcher.
I asked about the F-21 At motors because a local vendor offered some to me, but I intend to fly it on AT E-30's or E-15's.
I also intend to use a How High altimeter to determine the max. altitude with this configuration and with an unaltered 80 BB NC. Ted

 

[shockie]

https://www.spacemodeling.org/JimZ/enerjet/ejn02.pdf


Terry Dean

 

[bobkrech]

Thank you to everyone for your responses. What I intend to build is a 3x24mm cluster in an unusual? design. It's based on a BT-80 airframe 34" long with an Estes 80BB NC. The NC has a central 28mm aperture with a 25mm I.D. tube to it and protruding from the base of the NC. A 24mm tube mounted centrally with 3 CR's through the BT mates with it and continues all the way to the motor mount. There it reduces to 16mm and provides an air passage to the area below the recessed MMT. The fins will be 1/8 TTW plywood elliptical high aspect ratio 5" long, 1.7" span. The rocket is basically a flying thick-walled tube with elliptical fins. The space between the tubes will house the parachutes and conduct the ejection gases forward. I'm aware of the drag penalties with the increased surface area from the central tube.
I plan to launch the rocket inside a six foot length of 6" sonotube with a tough paper cone on the rocket base to make it a piston launcher that will drag separate after exiting the launcher.
I asked about the F-21 At motors because a local vendor offered some to me, but I intend to fly it on AT E-30's or E-15's.
I also intend to use a How High altimeter to determine the max. altitude with this configuration and with an unaltered 80 BB NC. Ted

Ted

The only model rocket that has a chance to go supersonic is a minimum diameter design. With the 80 N average thrust restriction large diameter rockets can't do it. I can say with certainty that your rocket can not go supersonic. The drag is just too high.

Bob

 

[Rocketjunkie]

:jaw::eyepop::y:

I need to try that. Green monkey aerospace? What propellant?

"BANG!" and it would be gone...:bangbang:

It's my own design. Threaded closures, smoky zinc/AP propellant. I've attached the thrust curve for the motor.

View attachment d40d.bmp

 

[Rocketjunkie]

This one was the motor of choice for sonic attempts for many years:

https://www.thrustcurve.org/motorsearch.jsp?id=91

https://nar.org/SandT/pdf/Aerotech/G55.pdf

Not currently certified, not currently in production.

There were also G110 motors back then. Blue Thunder versions of the G55. Easy mach busters

 

[dedleytedley]

Ted

The only model rocket that has a chance to go supersonic is a minimum diameter design. With the 80 Ns average thrust restriction large diameter rockets can't do it. I can say with certainty that your rocket can not go supersonic. The drag is just too high.

Bob

Bob I'm sure you're right but I do think it will be a rocket worth building. If nothing else it should make an interesting noise. My Skyscoop does. Ted

 

[shreadvector]

There were also G110 motors back then. Blue Thunder versions of the G55. Easy mach busters

But those would not be "Model Rocket Motors" and the original post is specifically looking to go supersonic with a legally defined Model Rocket using Model Rocket Motors.

Hence my listing the link to the handy graphic. Be sure to click on it, save a copy, print a copy and read it. Good stuff.

 

[MarkII]

Does the F100-0 simulation file actually represent the real F100-0?

By that I mean:

1) What alleged total-impulse and thrust curve is in the sim file?

2) Does it correctly include the delay time? YES, I said delay time. F100-0 motors had a delay and an ejection charge with no cardboard cap on top. They had a very short delay (1 or 2 seconds) so that the motor would not blow through during burn sinc ethey were operating on the hairy edge of the design limits. The delay helped keep it intact and the ejection charge was the granular BP they normally used but it had a clear laquer covering the top so that it could blow upward and ignite an upper stage.

I can't make any judgment about the accuracy of the motor file, because I have never ever flown, or even seen, an actual FSI motor of any kind. I have no information about how their motors were constructed, other than knowing their overall dimensions (as stated in FSI catalogs) and the fact that they used black powder for propellant. I don't know the identity of the author of the FSI motor files in the EMRR archive, and I don't know what information was used to create them. I just used what was available, and I stated that the results came from a simulation of a flight, not from actual flight data. (Caveat emptor was implied, if not explicitly stated.) As I said before, I don't know if the Dart ever actually broke Mach; FSI claimed that it did do in their testing, but I actually have no experience at all with any of the company's products. They made no claims about its ability to reliably do so, though, and indicated in the kit's instructions that going supersonic would present a challenge to the flier in any event. FSI flourished and then went out of business during my 33 year sabbatical from flying model rockets.

I appear to have used an incorrect term when I mentioned where on the ground an observer would need to be stationed in order to detect a sonic boom generated by the Dart going supersonic. What I was referring to was where the Mach cone intersects the ground, not the shock wave.

MarkII

 

[Ted Cochran]

The Mach Buster from Rocket Vision did it years ago. I was never able to recover this tiny beast, because when you used the Rocket Vision recommended motors once it left the pad that is the last time you see it.

I flew mine four times, and recovered it 3-1/2 times, on F101 and G55 motors. (I'll claim the number of recoveries as a world record!) It only weighed a few ounces, and the sims say it should break Mach 1 with some margin to spare. The trick to getting it back was to launch on clear, low humidity days, or at launches with lots of people out looking. Even then, the one and only time I launched it on a G55, it disappeared. Half of it was found by accident a couple months later.

Fun rocket!