F impulse altitude record

madcow rocketry
Wildman Rocketry
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n27sb said:
Thanks Bill, you were already on my list but I noticed that you don't make 24mm.
Just layed up the BT for this little guy and after trim out it will be under a 1/2 oz. OD is about .970
I would be happy to pay you for a set or make you some CF BT or nose cone.
Nose cone halves glassed and bagged. I love days off.



View attachment 261074View attachment 261075
Click to expand...

If you have a little extra tubing I could test-fit things around and some idea as to how long they can be then I can give it a shot. It's not clear to me that the printed version will scale down well that far, but there's only one way to find out and that's to try it. I do have a 29mm version in early testing, and I'm plugging away at 54mm development as fast as possible.
 
This might fit.
Eggfinder GPS
Easymini
2 cell lipo
Falcon tracker
Looks like a lot of weight but I need it for the mass I projected.
Right now at 6.52 Oz total weight wet and ready to fly including streamer and engine.
2.2 stability margin
photo.jpg
 
No, I don't have it. I have never had to fine tune anything like this before.
 
n27sb said:
Thanks Bill, you were already on my list but I noticed that you don't make 24mm.
Just layed up the BT for this little guy and after trim out it will be under a 1/2 oz. OD is about .970
I would be happy to pay you for a set or make you some CF BT or nose cone.
Nose cone halves glassed and bagged. I love days off.



View attachment 261074View attachment 261075
Click to expand...
Just be aware that a CF airframe is electromagnetically opaque. EM signals such as GPS can not get in, nor can radio signals get out.

Bob
 
bobkrech said:
Just be aware that a CF airframe is electromagnetically opaque. EM signals such as GPS can not get in, nor can radio signals get out.

Bob
Click to expand...

I might actually be ahead of you this time. The nose cone is FG and the tracker is exposed on deploy.
Thanks for watching my back.
 
That's a very nice job for something knocked together in a couple of hours from scrap.

Y'know the nice thing about making the rocket black? You can put a bunch of powdered graphite on the tower rails and it won't show.
 
Don't forget to make the surface really smooth. The difference between an average surface finish and a perfect finish is 2500'. A Pro24 F51 has a slight advantage over the F30. You can expect somewhere around 7 kft with a good finish with a 6.5 oz. liftoff weight.

Bob
 
Thanks Bob, what did you run that on? I got a little better performance out of the F30 long burn. I thicken up the fins and plug in rough surface to get rocksim to tell the truth.
I plan on turning the cone on the lathe to reduce a little more weight and I will be doing field work for 2 weeks for my company. That means sitting around at night wet sanding parts.
I don't have to have both an RF tracker and Gps but I would like to find this bird and fly it several times. Maybe later I will dump the Gps and go really light. I could also reduce the battery some.
Thanks for the input.
 
Just a quick and dirty on thrustcurve.org FWIW.

The reason why I checked it out was from the photos your airframe looked like it wasn't too smooth and that will hurt any altitude attempt.

Watch out for weakening the NC. You might have a fair bit of dynamic pressure on it and you don't want it to buckle. You want to check what the optimum weight is for your specific airframe/motor combo. You can actually be too light and loose altitude because you do not have the optimum retained momentum to sustain a maximum coast time/distance.

Bob
 
Bob, Your quick check is right on the money. Rocksim puts it at 7200. The optimum weight seems to be about 6.5 oz. As you go lower the altitude falls off. I guess that I will be a little over 7 oz but that seems to have little effect. Sure wish I could get my hands on some old Aerotech F72 motors.
The body has not been sanded at all. That is the rough lay up finish. I usually wet sand and knock most of the high spots off. This removes structure but overall the tube stays very rigid. I finish it up with a few coats of clear laquer and more wet sanding.
 
bobkrech said:
Just a quick and dirty on thrustcurve.org FWIW.

The reason why I checked it out was from the photos your airframe looked like it wasn't too smooth and that will hurt any altitude attempt.

Watch out for weakening the NC. You might have a fair bit of dynamic pressure on it and you don't want it to buckle. You want to check what the optimum weight is for your specific airframe/motor combo. You can actually be too light and loose altitude because you do not have the optimum retained momentum to sustain a maximum coast time/distance.

Bob
Click to expand...

On my models, I hollowed out the balsa cones as much as I could. Less velocity with an F-10 though, but it's helpful for stability to get as much stuff as high as you can. I put a tracker and an altimeter in one cone and a tracker and battery pack in another.

Jim
 
n27sb said:
Bob, Your quick check is right on the money. Rocksim puts it at 7200. The optimum weight seems to be about 6.5 oz. As you go lower the altitude falls off. I guess that I will be a little over 7 oz but that seems to have little effect. Sure wish I could get my hands on some old Aerotech F72 motors.
The body has not been sanded at all. That is the rough lay up finish. I usually wet sand and knock most of the high spots off. This removes structure but overall the tube stays very rigid. I finish it up with a few coats of clear laquer and more wet sanding.
Click to expand...
The only advantage of the AT 24mm SU F72 over the Pro24 F51 is the casing weight of the SU is 20 g lighter. The F51 has a lower peak thrust and a slightly longer burn so IMO its the thrust curve is better, and it is much better than the Pro24 F30.

A trick you can try to get the surface smoother is to lightly sand the airframe and then mix up some low viscosity laminating resin and apply it to the airframe and using your thumb and forefinger in a nitrile glove, work the resin into the void and let it air dry. This can give a very smooth surface.

Bob
 
bobkrech said:
The F51 has a lower peak thrust and a slightly longer burn so IMO its the thrust curve is better, and it is much better than the Pro24 F30.

Bob
Click to expand...
I think you are right. I hope to be lucky enough to Fly both. The Organic Soup of aerodynamics sometimes finds it's own way.
 
Can you piston-launch the rocket to set a record? Also, Using an F10, your speed will not come near Mach 1, so using a heavy FG or CF rocket may not be as effective as using simple paper and balsa. Don't overthink this. A Jolly Logic altimeter and a Beeline tracker, placed in a payload section of a 24mm min. dia. rocket with papered balsa fins, a balsa nose cone and assembled with carpenter's glue will work fine. Friction-fit the motor. Take a look at this design. or buy an Apogee Aspire for $20.

F record.jpg
 
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EeebeeE said:
Can you piston-launch the rocket to set a record? Also, Using an F10, your speed will not come near Mach 1, so using a heavy FG or CF rocket may not be as effective as using simple paper and balsa. Don't overthink this. A Jolly Logic altimeter and a Beeline tracker, placed in a payload section of a 24mm min. dia. rocket with papered balsa fins, a balsa nose cone and assembled with carpenter's glue will work fine. Friction-fit the motor. Take a look at this design. or buy an Apogee Aspire for $20.
Click to expand...

Thank you Evan for your input. I like your Quote "History doesn't repeat itself, but it does have a tendency to rhyme. - Mark Twain "
I think it is pertinent here. Many guys have traveled this path. Here are my thoughts on each item. Some are mine and some absorbed from the generosity of forum members.
1. I think you can piston launch but it is not easy with the motors I plan to use.
2 An F10 would push me up to a 29mm frame and I would like to see what I can do in 24mm.
3. FG and CF rockets tend to be too heavy because they are usually overbuilt. By using CF in the fin can I can build lighter than paper and balsa and have a thinner fin profile. I also get better durability for the recovery phase.
4. Because all of the motors I have to choose from have too short of a delay I need my Dual Mini to deploy at max apogee. The Eggfinder GPS Is a little heavier than I would like but as it turns out I may have built the airframe too light for maximum coast so it helps out with some added weight in the nose. I probably do not need the Falcon RF tracker but some of the areas I fly in have rough terrain. Sometimes you hear the crunch of stepping on your rocket before you see it. The Falcon RF can take me to within 1 foot.
5. I plan on friction fitting the motor.
6. I like your design, I plan on trying a 29mm later to compare. Hope to fly side by side with yours one day.
7. Apogee Aspire? I think Tim makes great kits but part of the fun for me is building as much of the rocket as I can from raw materials.
How am I doing Bob?
Thanks again Evan for your thoughts. I look forward to more.
 
n27sb said:
[4.] I probably do not need the Falcon RF tracker but some of the areas I fly in have rough terrain. Sometimes you hear the crunch of stepping on your rocket before you see it. The Falcon RF can take me to within 1 foot.
Click to expand...
What about a screamer?
 
n27sb said:
Thanks Bill, you were already on my list but I noticed that you don't make 24mm.
Just layed up the BT for this little guy and after trim out it will be under a 1/2 oz. OD is about .970
I would be happy to pay you for a set or make you some CF BT or nose cone.
Nose cone halves glassed and bagged. I love days off.



View attachment 261074View attachment 261075
Click to expand...

What's the final measured OD of your airframe? Do you have a spare piece? I'm thinking fly-aways here...Weekend prototyping time coming up...
 
wfcook said:
What's the final measured OD of your airframe? Do you have a spare piece? I'm thinking fly-aways here...Weekend prototyping time coming up...
Click to expand...

I built a launch tower but I would use a fly-away if it would help promote your stuff. PM an address and I can send you some tube.
 
RAHagen said:
That's a nice mold! I'm curious, how did you go about making it? I'm thinking of getting into making my own cones.
Click to expand...

John Coker has an excellent 2 part video on this subject. I can't do a better job than he does.
I do use an internal insert to control the ID.
[video=youtube;Lo_g1VOVAcg]https://www.youtube.com/watch?v=Lo_g1VOVAcg[/video]
[video=youtube;5KmTImQsHIk]https://www.youtube.com/watch?v=5KmTImQsHIk[/video]
 

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