B Engine Altitude Competition

[Harrison Vance]

Good Morning All,

Does anyone know of any articles, books, or sources where I can find some knowledge on achieving the best altitude for this competition? I’ll be designing this rocket from scratch and of course making it the lightest possible. I’m participating in this event at NARAM-63. If anyone has any info on designing a B Engine rocket for altitude let me know. Thanks!

Swaggy

 

[RocketTree]

The most lightweight design will often get you a higher top speed, but lower altitude. Optimizing mass of the rocket by adding a specific amount of nose weight will provide the highest altitude for a given motor (while also reducing top speed). This can be found by simulating the design in OpenRocket or Rocksim.

You may find some related articles in a search of the Apogee newsletters.

 

[BEC]

https://www.nar.org/contest-flying/competition-guide/altitude-events/altitude/

 

[MidOH]

Make a rocket that flys straight is as important as light weight. Beyond that, studying articles, sources, and books, is going to take the fun out of it. Trying something new and innovative, ain't going to be in them.

If everybody's rocket flies like a curvy back road, the guy with the fiberglass brick wins.

 

[Ez2cDave]

Minimum Diameter . . . Minimum Drag . . . Optimum Weight . . . Piston Launcher . . . Tower . . . Use the altimeter for deployment, not the ejection charge in the motor . . . Fly a Booster motor and TEMPORARILY "plug" the forward end of the motor ( Under the rules, you can't PERMANENTLY "plug" a motor. ).

https://www.nar.org/contest-flying/competition-guide/altitude-events/altitude

https://www.nar.org/wp-content/uploads/2014/05/Altitude-Payload-Events-Wolf.pdf

Dave F.

 

[kkooch]

Minimum Diameter

Umm. No and for minimum drag. Constant curvature, yes. And this will mean making models whose diameter are a bit greater than the minimum but that are constant curvature throughout.

Kooch

 

[Ez2cDave]

Umm. No and for minimum drag. Constant curvature, yes. And this will mean making models whose diameter are a bit greater than the minimum but that are constant curvature throughout.

Kooch

That's intriguing !

Do you have any pics of competition rockets using this type of design ?

Thanks,

Dave F.

 

[Alan15578]

Umm. No and for minimum drag. Constant curvature, yes. And this will mean making models whose diameter are a bit greater than the minimum but that are constant curvature throughout.

Kooch

For NARAM B altitude, min diameter is fine. For the FAI big fat bodies, you should consider minimum drag natural laminar flow design.

 

[Jeff Lassahn]

Use the altimeter for deployment, not the ejection charge in the motor

How does that work on a minimum diameter 18mm rocket? I would have expected all the extra stuff needed for altimeter based deployment would be too large and heavy for this kind of design.
It would be cool to find out I'm wrong about that!

 

[Ez2cDave]

How does that work on a minimum diameter 18mm rocket? I would have expected all the extra stuff needed for altimeter based deployment would be too large and heavy for this kind of design.
It would be cool to find out I'm wrong about that!

Actually, probably 95+% of all NAR Altitude events use an altimeter to measure altitude, rather than setting up for optical tracking.

There are altimeters that fit into a 13mm BT-5 tube ( one model, that I know of, has a "deployment" feature ) . . .

So, the model is constructed to carry the altimeter, either in a payload section or the nose cone. An electric match or a flashbulb is hooked up ( embedded in a small Black Powder charge. Use a "plugged" Booster engine and, when the model reaches apogee, the altimeter fires the ejection charge.

Dave F.

 

[dhbarr]

How does that work on a minimum diameter 18mm rocket? I would have expected all the extra stuff needed for altimeter based deployment would be too large and heavy for this kind of design.
It would be cool to find out I'm wrong about that!

The very smallest deploying altimeter I know of is @bdureau's altiDuo, ~10g including battery.

 

[Ez2cDave]

The very smallest deploying altimeter I know of is @bdureau's altiDuo, ~10g including battery.

Adrel "DeployMax" . . .

https://www.apogeerockets.com/Electronics-Payloads/Altimeters/Adrel-DeployMax-Single-Deployment-Altimeter

Instruction Manual https://www.apogeerockets.com/downloads/PDFs/09234_Adrel_DeployMax_060621_C.pdf







Dave F.

 

[bdureau]

The very smallest deploying altimeter I know of is @bdureau's altiDuo, ~10g including battery.

This is the smallest dual deployment altimeter that I made to date

 

[GuyNoir]

The very smallest deploying altimeter I know of is @bdureau's altiDuo, ~10g including battery.

https://northcoastrocketry.com/products/adrel-deploymax-altimeter-single-event-deployment

 

[Harrison Vance]

https://northcoastrocketry.com/products/adrel-deploymax-altimeter-single-event-deployment

Just bought this one recently. It is indeed the smallest!

 

[kkooch]

For NARAM B altitude, min diameter is fine. For the FAI big fat bodies, you should consider minimum drag natural laminar flow design.

Fine yes, but not optimum. At the last World Champs in Romania, winning B Altitude and C Scale Altitudes were laminar flow designs and they eclipsed by a good margin, all other models that did not incorporate this technology.

 

[Ez2cDave]

Fine yes, but not optimum. At the last World Champs in Romania, winning B Altitude and C Scale Altitudes were laminar flow designs and they eclipsed by a good margin, all other models that did not incorporate this technology.

I'd like to see those FAI / WSMC models flown "clean", without using a piston launcher, and using Estes BP motors.

Question - How can you use a "laminar flow design" on a Scale model ?

Do you have any pics of those FAI / WSMC Scale Altitude models ?

Dave F.

 

[rAUM]

This is the smallest dual deployment altimeter that I made to date
View attachment 522817View attachment 522818

Hi man, I saw your awesome designs, I want to buy (maybe a couple after trying out) a dual deployment altimeter with bluetooth connection/wifi connection. However I can't find where to buy it or your contact details. Would appreciate an answer.

 

[kkooch]

That's intriguing !

Do you have any pics of competition rockets using this type of design ?

Thanks,

Dave F.

 

[bdureau]

Hi man, I saw your awesome designs, I want to buy (maybe a couple after trying out) a dual deployment altimeter with bluetooth connection/wifi connection. However I can't find where to buy it or your contact details. Would appreciate an answer.

Just send me a PM

 

[aerostadt]

Does NAR Competition allow all altimeters for B-motor Altitude Competition?

 

[rharshberger]

Does NAR Competition allow all altimeters for B-motor Altitude Competition?

Just the ones on their approved list.

 

[aerostadt]

Thanks, Rich. The criteria for approved altimeters and the approved list can be found here:
https://www.nar.org/contest-flying/...ting-code/altitude-competition/altitude-data/

 

[Ez2cDave]

Thanks, Rich. The criteria for approved altimeters and the approved list can be found here:
https://www.nar.org/contest-flying/...ting-code/altitude-competition/altitude-data/

https://www.nar.org/contest-flying/u-s-model-rocket-new-sporting-code/appendices/appendix-e-altimeters-approved-for-contest-use

 

[kkooch]

I'd like to see those FAI / WSMC models flown "clean", without using a piston launcher, and using Estes BP motors.

Question - How can you use a "laminar flow design" on a Scale model ?

Do you have any pics of those FAI / WSMC Scale Altitude models ?

Dave F.

Dave- the performance improvement is around 30% and without the use of pistons. Substantial and documented!
I don't have any pics of the RU/UKR scale altitude models, but knowing they used laminar flow shapes, it would only have to be a subtle curve ramp up to the main dia and then ramp down to the end. The judges may not have measured diameters on different parts of the body, or if they did, the modeler got docked a few points for being slightly out of spec. But these inaccuracies and possible point reductions because of, more than made up in their altitudes.

 

[Ez2cDave]

Dave- the performance improvement is around 30% and without the use of pistons. Substantial and documented!

Hmm . . . I foresee a problem, if using Estes BP motors . . . The delays may not be long enough for a 30% increase in performance.

Other than the "specialized" European motors, how does one compensate for the additional performance, in terms of deployment, using Estes motors ?

Dave F.

 

[aerostadt]

I am puzzled by what people here are calling laminar flow for a B-motor sized rocket. If I calculate the Reynolds number for such a rocket, I get a Re number on the order of 2 million, which should be in the turbulent flow regime. Are people referring to some kind of shape of the rocket that minimizes the size of the turbulent wake?

 

[kkooch]

I am puzzled by what people here are calling laminar flow for a B-motor sized rocket. If I calculate the Reynolds number for such a rocket, I get a Re number on the order of 2 million, which should be in the turbulent flow regime. Are people referring to some kind of shape of the rocket that minimizes the size of the turbulent wake?

You can still have laminar flow at those Rn. Note that the model does not stay at that high an Rn throughout the flight. The key is having a program where you can vary the shape, plug into 3d CFD program that will output varying Cd vs Rn, and then go fly that model with an altitude program that accepts a varying Cd v. Velocity. Rinse and repeat until you have a model whose flow stays laminar as far back on the model as is possible and as long as possible throughout the flight regime; boost and coast.

Here are two performance runs, using the same motor, same liftoff weight, same length and same general max diameter over a specified length. The KKlamx is a laminar flow design and is actually 1.5mm larger diameter than the ECB. The ECB is not laminar (at least from a bit past the nose/body juncture to the motor end) and stands for Elliptical nose cone, Cylindrical body and conical Boat tail. The ECB is what I would consider your standard NAR altitude design.

 

[aerostadt]

You can still have laminar flow at those Rn. Note that the model does not stay at that high an Rn throughout the flight. The key is having a program where you can vary the shape, plug into 3d CFD program that will output varying Cd vs Rn, and then go fly that model with an altitude program that accepts a varying Cd v. Velocity. Rinse and repeat until you have a model whose flow stays laminar as far back on the model as is possible and as long as possible throughout the flight regime; boost and coast.

Here are two performance runs, using the same motor, same liftoff weight, same length and same general max diameter over a specified length. The KKlamx is a laminar flow design and is actually 1.5mm larger diameter than the ECB. The ECB is not laminar (at least from a bit past the nose/body juncture to the motor end) and stands for Elliptical nose cone, Cylindrical body and conical Boat tail. The ECB is what I would consider your standard NAR altitude design.

Very Interesting Stuff!. Your graphical comparison is quite striking. However, I am having trouble seeing the units for velocity. Is it fps or m/secs? What size motor is this? I assume that the shape you are using is similar to post#19, right? I assume that for a more powerful motor it will be more difficult to keep the model in laminar flow during the total flight.

 

[kkooch]

Very Interesting Stuff!. Your graphical comparison is quite striking. However, I am having trouble seeing the units for velocity. Is it fps or m/secs? What size motor is this? I assume that the shape you are using is similar to post#19, right? I assume that for a more powerful motor it will be more difficult to keep the model in laminar flow during the total flight.

Thank you. m/s. This is a Ukrainian A1 motor and you are correct on the model in post 19. Also yes and for high impulse, high velocity models, the goal would be attached turbulent flow. This is not to tough to accomplish. Just avoid large angle changes on the body.