BaddAzz Rocktery's "Das Blitzzkrieg" Build

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Take a look at the Apogee web site they have a section where they talk about a rocket being over stable. One thing they did say was a high thrust motor works better for a over stable rocket. Some how do you have a lot of weight in the back end of the rocket?

Seems to me like over stable would mean adding weight to the rear end..... nose weight to add stability.

Is there a Rocsim file for this rocket? Would like to see the numbers for myself. Maybe some others have this kit built and have flown them..... surely I am not the first (besides Eric of course)

Barry
 
Eric. Do you have a rocksim file for this
Rocket? I just purchased and realized I
didn't see a downloadable file?
 
Over stability in itself isn't bad the problem comes when wind hits it...basically it "tips over" in flight you can remove nose weight if you have any and that should correct the problem...also make sure you don't use motors that are to small where stability is an issue a small motor won't provide enough thrust and it may tip over...if no changes can be made then stick with higher thrust motors ( which that kit is built for) and no wind type days. Good luck!
 
Seems to me like over stable would mean adding weight to the rear end..... nose weight to add stability.

Is there a Rocsim file for this rocket? Would like to see the numbers for myself. Maybe some others have this kit built and have flown them..... surely I am not the first (besides Eric of course)

Barry

Barry I don't share my Rocksims.
Adding rear weight does not correct this issue.
The higher thrusting motors are the trick.

Barry, the Das BlitzzKrieg was flown on an H123 at Orangeburg 2 months back.
The flight was good. The rocket is a 3.5 overstable condition with that motor.
If you are gonna fly try the I213SK that put's it at an 2.85 overstable state.
The J410RL is at 2.97 overstable.

I found the rocket to fly true at these conditions. That said I want feedback from all Owners!!! I can correct this by making a 4:1 Nosecone and reducing length to 48". If these issues are consistant, I want to make it right. That said I don't intend to stop production from one bad flight (No disrespect Barry). I just don't want to knee jerk here.
Give me more feedback.


Thanks
Eric Foster
 
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Eric,

Thanks for the feedback. I was hesitant to post anything but I wanted to figure out what went wrong and who would know better but the designer :wink:

I am going with the assumption that my CG was too far forward at this point. It was about 20" and I have spent the evening fiddling with it. I had a Skyangle main chute that added 4oz to the payload area. Removing that and putting a smaller chute and adding 5oz to the motor area (with a 7.6oz motor installed) brought me to about 16-17" forward of rear. I could try a lighter battery than the standard 9v....... am I on the right track?

So you are saying use a faster burn motor as well? Mine yesterday was Avg 123.... total 228 at a 2 sec burn.

thanks again,

Barry
 
Just curious, Why didn't you use the chute in the kit?
Use the I or J ! Yes think Surface to Air, Not Cruise and The battery is not an issue!!
Still One freakin weird flight though. You have better luck than me.
If that had been mine it would have been a trash can retrieve!

Eric Foster
 
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Eric,

I had a problem three weeks back with a flat chute and the lines getting tangled. The chute fluttered the entire way down and never opened. I like the 3-4 shroud line chutes for that reason. The Skyangle with 3 looked promising in the 36" size. Never thought about the weight difference. I would rather spend a little more and get the best. Nothing wrong with your chute probably...... just my bad experiences made me leery of it.

In hindsight... it may have made the entire flight go differently:yawn:
 
Eric,

I had a problem three weeks back with a flat chute and the lines getting tangled. The chute fluttered the entire way down and never opened. I like the 3-4 shroud line chutes for that reason. The Skyangle with 3 looked promising in the 36" size. Never thought about the weight difference. I would rather spend a little more and get the best. Nothing wrong with your chute probably...... just my bad experiences made me leery of it.

In hindsight... it may have made the entire flight go differently:yawn:

No big deal, I was just curious. I chose these because of the good luck I've had. My biggest problem was learning a proper packing technique , To each his own! Sky angle is a great chute!

Eric
 
I will honor Eric's statement below and not post my Rocksim file unless I am told otherwise. I do have all the correct weights and dimensions (at least for the components I have), but have not (do not know how) to account for the fin cut outs. I will say my results match Eric's within ~6%, but then I have both altimeter/battery accounted for and a tracker in the NC. It is clearly a somewhat overstable rocket due to the weight of the airframe, but not alarmingly so when compared to many longer profile rockets made of more traditional materials.

Barry I don't share my Rocksims.
Adding rear weight does not correct this issue.
The higher thrusting motors are the trick.

Barry, the Das BlitzzKrieg was flown on an H123 at Orangeburg 2 months back.
The flight was good. The rocket is a 3.5 overstable condition with that motor.
If you are gonna fly try the I213SK that put's it at an 2.85 overstable state.
The J410RL is at 2.97 overstable.

I found the rocket to fly true at these conditions. That said I want feedback from all Owners!!! I can correct this by making a 4:1 Nosecone and reducing length to 48". If these issues are consistant, I want to make it right. That said I don't intend to stop production from one bad flight (No disrespect Barry). I just don't want to knee jerk here.
Give me more feedback.


Thanks
Eric Foster
 
Cut out fins aren't all that hard...you can easily emulate them with two sets of custom fins.
 
What? Overlay fins with "zero corrective force"? How?

DUH!!! Nevermind. I get it (switching back over to Rocksim window...).

Cut out fins aren't all that hard...you can easily emulate them with two sets of custom fins.
 
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OK, got it (talking to himself), I'm now within 1% of Eric's numbers for stability. Cut out fins were implemented as complex, custom fins as suggested by Dick.

What? Overlay fins with "zero corrective force"? How?

DUH!!! Nevermind. I get it (switching back over to Rocksim window...).
 
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Im a bit confused? this is the first time ive ordered a rocket where the manufacturer wont share rock sim files with the paying customers?
what is the issue? I would like to simulate the flights based on the aerotech motor casings? i need to know where the cp and CG are and general altitudes?
for the 29/180 29/240 and 29/360 motors.

this is a safety issue?
Eric - I have sent you a private message if you would prefer not to post the response.
Thanks
 
Im a bit confused? this is the first time ive ordered a rocket where the manufacturer wont share rock sim files with the paying customers?

In my experience, there are few manufacturers who do provide RockSim files. I admit my experience with HPR kits is limited, since the vast majority of my projects begin with me creating the RockSim file, then ordering materials from the manufacturers, as I typically build from scratch.

I could go do the research... but it would be easier to ask...

What major manufacturers out there do provide RockSim files? Anybody?
 
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LOC/ Precision
Aerotech G-Force and Sumo
MadCow
PML
Wildman
Always Ready Rocketry
Pemberton

thats just the ones I have received from the manufactures. I am sure they are more. We are talking about a kit and we are talking about safety as well.

In theory any of these could be reverse engineered but you dont need a rocksim to do that. you just buy the kit.
 
LOC/ Precision
Aerotech G-Force and Sumo
MadCow
PML
Wildman
Always Ready Rocketry
Pemberton

thats just the ones I have received from the manufactures. I am sure they are more. We are talking about a kit and we are talking about safety as well.

In theory any of these could be reverse engineered but you dont need a rocksim to do that. you just buy the kit.

Request being reconsidered.

Eric
 
Eric,

I have been analysing my kit.... trying to adjust my CG. I cut 2" from the payload section. Reduced some hadrware weight..... hated to looose the quick links. Managed to get the CG to 18" from rear.... or a 3.8 over stable if my numbers are right.

Feel much better about things.... still Love The kit. Well made and easy to build. Just received another kit that $40 more and not near the quality. Keep up the good work Eric.......
 
Thanks for the good words BearMan!

I'm tooling a new mould for a 4:1 Nosecone with a 1" shoulder. This adjustment will be a tremendous step in correcting the over stabilty issue. Please shorten your Payloadbay (from the nose cone side) to 13" OAL. I'm getting <3x over stable now on H123. Of course Cp changes also, Now 7" from base.
For those of you who have already purchased the nose replacement is free, I ask you please cover shipping costs at $7.00.

Please review the Rocksim!

Thanks a Bunch,

Eric Foster

View attachment Blitzkrieg_DD (2).rkt
 
Good for you, Eric, way to step up. Think a Blitzkreig is in my future! John.
 
Hi All,

Just wanted to post an update.....

Have done some work to my Das Blitzzkrieg since I flew it 5 weeks ago.

I looked my build over and removed as much weight as possible and moved weight rearward to reduce overstability as much as possible. I removed extra screws and cut off bolts..... added Loctite instead of locking nuts.... ditched the great charge cups for nuts instead. Shortened the payload section to 12" and replaced the nose cone with Erics new one.

Now for my prior flight I had installed a heavier chute and had overstability factor of around 5....... with my changes I was able to get it to 1.74 with a H153 CTI. Now I didn't triple check everything but the flight yesterday was PERFECT!!!! Straight... no weathercocking..... no spin..... AWESOME FLIGHT 2226ft on the H153

It seems strange but just a bit here and a tad here and it all adds up to a great rocket. I did make one error..... forgot to redrill the shear pin holes for the nose cone and my 1 gram charge at apogee make the nose cone loosen and the main deployed early. Drifted into a soybean field but found it after a little looking. :D:D:D:D:D:D:D:D:D
 
Hi All,

Just wanted to post an update.....

Have done some work to my Das Blitzzkrieg since I flew it 5 weeks ago.

I looked my build over and removed as much weight as possible and moved weight rearward to reduce overstability as much as possible. I removed extra screws and cut off bolts..... added Loctite instead of locking nuts.... ditched the great charge cups for nuts instead. Shortened the payload section to 12" and replaced the nose cone with Erics new one.

Now for my prior flight I had installed a heavier chute and had overstability factor of around 5....... with my changes I was able to get it to 1.74 with a H153 CTI. Now I didn't triple check everything but the flight yesterday was PERFECT!!!! Straight... no weathercocking..... no spin..... AWESOME FLIGHT 2226ft on the H153

It seems strange but just a bit here and a tad here and it all adds up to a great rocket. I did make one error..... forgot to redrill the shear pin holes for the nose cone and my 1 gram charge at apogee make the nose cone loosen and the main deployed early. Drifted into a soybean field but found it after a little looking. :D:D:D:D:D:D:D:D:D

Great News Barry!

Now that's Flyin BADDAZZ STYLE!:headbang::headbang::headbang::headbang::cheers:

Eric Foster
 
Oh it was wonderful...... Have a H400 VMAX ready for next months launch..... Have an I and J as well...... Good times
 
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