18mm MD 2000 ft on a C6

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In competition land it used to be pretty common to break 2kft on a C6, even with a 1oz payload(!). The FAI payload world record is/was somewhere north of 700m and I personally did 667m a long time ago. The current NAR C altitude with altimeter record seems awfully low. Use a 30"+ piston and a mirror finish, and watch the wetted area; too much fin is a serious detriment. And it has to be built dead straight. The worst problem is that the nominal 7 sec delay is too short for the altitude and you're ejecting on the way up a couple of seconds early.
 
caveduck said:
In competition land it used to be pretty common to break 2kft on a C6, even with a 1oz payload(!). The FAI payload world record is/was somewhere north of 700m and I personally did 667m a long time ago. The current NAR C altitude with altimeter record seems awfully low. Use a 30"+ piston and a mirror finish, and watch the wetted area; too much fin is a serious detriment. And it has to be built dead straight. The worst problem is that the nominal 7 sec delay is too short for the altitude and you're ejecting on the way up a couple of seconds early.
Click to expand...
I'm not actually going for the altitude record, if i was i would use a more optimized nose cone and 0.3 mm CF fins. I'm just really playing around with this build and having fun. And according to OR the 5 sec delay is fine.
 
retortec said:
Please use idea of the beveling jig. If you can improve it let me know. I have successfully used it all the way down to .5mm carbon plate. Checking the bevel at .5 is another story. Many times I need to wear a jewelers loop.:)
Click to expand...
Yeah i have some spare wood blocks around the house so ill try and use it and see what i get. :)
 
caveduck said:
In competition land it used to be pretty common to break 2kft on a C6, even with a 1oz payload(!). The FAI payload world record is/was somewhere north of 700m and I personally did 667m a long time ago. The current NAR C altitude with altimeter record seems awfully low. Use a 30"+ piston and a mirror finish, and watch the wetted area; too much fin is a serious detriment. And it has to be built dead straight. The worst problem is that the nominal 7 sec delay is too short for the altitude and you're ejecting on the way up a couple of seconds early.
Click to expand...


Some thing like this.

IMG_1848.jpgScreen Shot 2017-03-06 at 8.45.11 PM.jpgIMG_1685.jpg

My new launch site is over 5,000ft with super low humidity. Piston will add a solid 10% to the altitude. Same rig nearly hit 2300ft at 800ft above sea level with relatively high humidity. Hard part is trying to launch with no to little wind. Doesn't take much to send such a small rocket way off course.
 
Not really a record attempt either but a small detour in a low power supersonic build. The airframe is optimized for the D21with a PNut altimeter. But it does yield some interesting numbers with the C6-7. I have already blown up a couple pistons in an attempt to get that extra 5-10%. Without the piston the simulation tops out at Mach 1.16 at over 5,000ft. No room for a transmitter so tracking is a real problem. Still experimenting with a large start volume piston with magnetic hod down to overcome the D21's sputtering start.
 
Has anyone had success using a piston with composite motors?

retortec said:
Not really a record attempt either but a small detour in a low power supersonic build. The airframe is optimized for the D21with a PNut altimeter. But it does yield some interesting numbers with the C6-7. I have already blown up a couple pistons in an attempt to get that extra 5-10%. Without the piston the simulation tops out at Mach 1.16 at over 5,000ft. No room for a transmitter so tracking is a real problem. Still experimenting with a large start volume piston with magnetic hod down to overcome the D21's sputtering start.
Click to expand...
 
Peter Olivola said:
Has anyone had success using a piston with composite motors?
Click to expand...

I have come across a couple successful attempts. The initial start of a composite motor is such a variable I think conventional piston performance would follow. There are some new large volume piston designs used with black powder motors that give me a little hope. So dead end project? Probably...but fun to see if I can make some thing work. I will admit the simulation is for a monster high start altitude. I have some friends near Laramie WY and we launch near the summit of the pass (8,000+ ft) when we can.
 
A couple of NARAMs ago almost all the winning E egglofters used E6's off of pistons. But the WL propellant is pretty chuffy and I'd be leery of the D21. Another thing to watch out for is that with a really good piston and an ignitor with some pyrogen, the pyrogen burn may move the piston or even pop the rocket off even if the engine doesn't light. With many pyrogens the pressure spike is a lot sharper than the engine starting up.
 
Yeah i got the nose cone in a few days ago. I also just printed the fin templates and hopefully i should get them cut and beveled today.
 
Well actually I'm not really going for max altitude, this is just really a fun build (like a fly-and forget) rocket. In the link in my sig, that is the rocket that im going for COMPLETE optimization-check it out.
 
Now i need to find my Esztes porta pad II. If i can ill try to launch it within the week.
 
Do you know the weight and CG post-build? Could help you dial in the sims. If you don't have an altimeter, then just time the launch until it hits the ground. That could give you an idea of how total flight time compared to simulated flight time.

Wait for a zero wind or calm day to launch. Good luck!
 
Cabernut said:
Do you know the weight and CG post-build? Could help you dial in the sims. If you don't have an altimeter, then just time the launch until it hits the ground. That could give you an idea of how total flight time compared to simulated flight time.

Wait for a zero wind or calm day to launch. Good luck!
Click to expand...
I dont have a scale so i cant enter the weight into the file. But i did try to make it as accurate as possible otherwise.
 
TRFfan said:
Setup

View attachment 314158

Tube marked

View attachment 314159

Tube cut and sanded, launch lug CA'ed on. Motor was loaded in this shot.

View attachment 314160

Finished.

View attachment 314162

Also test fitted the wadding inside the BT.

View attachment 314161

Kinda hard to believe how small this is-it's barely larger than the C6 motor and is smaller than a pencil (see above picture). I can't believe that it's going to hit almost 2000 ft. :D :surprised:
Click to expand...

Tim VanMilligan's talk on aerodynamic properties of launch lugs suggest that the lowest drage configuration is to angle the leading edge of the lug but cut the trailing edge square.
 
dcullen said:
Tim VanMilligan's talk on aerodynamic properties of launch lugs suggest that the lowest drage configuration is to angle the leading edge of the lug but cut the trailing edge square.
Click to expand...
Oh ok. I thought that beveling the leading and trailing edge of the launch lug would get a better result like beveling a fin.
 
So, now i got the PSII and controller, i dont know why but the launch lugs dont fit on the rod anymore, maybe because some of the paint bled into them. Anyway, hopefully i should get new ones tacked on tomorrow and launch it in the evening. I will get some pics up tomarrow of the launch and rocket hopefully.
 
TRFfan said:
So, now i got the PSII and controller, i dont know why but the launch lugs dont fit on the rod anymore, maybe because some of the paint bled into them. Anyway, hopefully i should get new ones tacked on tomorrow and launch it in the evening. I will get some pics up tomarrow of the launch and rocket hopefully.
Click to expand...

Are you flying your 18mm MD on a C6? Try it on a Aero-Tech D21T. That will kick that rocket HARD! :clap::pop:
Can you try a video and/ some pictures?
Thanks,
 
TRFfan said:
I dont have a scale so i cant enter the weight into the file. But i did try to make it as accurate as possible otherwise.
Click to expand...
I am with Cabernut on this one. No scale? So you cannot even calculate the nose weight in your sim. On a rocket like that even a few grams will be the difference between ducking for cover and a successful flight. The sim is worthless. Very sloppy and dow right scary when thinking of your G150 build. Your better than that.
 
retortec said:
I am with Cabernut on this one. No scale? So you cannot even calculate the nose weight in your sim. On a rocket like that even a few grams will be the difference between ducking for cover and a successful flight. The sim is worthless. Very sloppy and dow right scary when thinking of your G150 build. Your better than that.
Click to expand...
I actually poured alot in the NC (more than needed). I could tell from the height that the wood glue came up to the nose shoulder. Also, i will try to get a scale for my other MD build. The only reason why i havnt gotten it yet it because i am short of funds.
 
TRFfan said:
I dont have a scale so i cant enter the weight into the file. But i did try to make it as accurate as possible otherwise.
Click to expand...

Try your local post office. I use to take my rockets there until I bought a scale!
 
Last edited by a moderator:
I get the funds thing. But we are talking about a nessisary tool in actually making the sim work. Borrow one or fined one at a agarage sale or whatever. Even having one for a short time you can make your own beam scale to use later. Just guessing when trying for extreme performance is sloppy.
 

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