Estes Ventris build for L1 cert

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mohmes

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I am a very recent BAR and have become enthralled with all of the HPR possibilities. Unfortunately I decided to wait until next year to enter the high power world and limit myself to some mid power rockets this year. So I got an Estes Pro Series II Ventris and then again unfortunately read some reviews of how people have had success launching this rocket with some small H motors. So now I think I will go for the L1 certification after all - sorry wallet.

I started the build by trying to do a little better job securing the roots of the fins to the motor tube. Basically I cut the bottom of the through the wall slots on the main body tube so after initially setting the fins I could slide the fins and motor mount out of the body tube. This allowed me to make some better fillets using wood glue. I would have prefered to use something else but I had deviated septum surgery 2 days prior and was still recovering. Because this glue was rather thin I built up about 5 layers for good solid fillets. I then made a small notch in the upper motor mount ring to allow the elastic shock cord to tightly slide through during assembly. I then glued the shock cord to the motor mount using a very liberal amount of glue. Should be nice and secure. I plan on using a kevlar sleeve over the shock cord along with a permanent kevlar wadding so the elastic should survive any ejection charges unharmed.

Ventris MM and Fins with Shock Cord.jpg

I tried using some of the wood glue to fill the spirals with limited success - I definitely don't have the patience like some of the pros on here - sanding just takes too long but I will suffer through it for this one. The motor mount and fins have been secured to the lower main body tube and a dry fit of the rest of the rocket is being shown off by my daughter.

Beth with Ventris Raw.jpg

One of the nice features of this rocket and another blow to my wallet is the upper section of the rocket can make a great electronics bay. It was actually seeing the Altus TeleMetrum (https://www.apogeerockets.com/Electronics_Payloads/Altimeters/TeleMetrum_Starter_Set) that has hooked me on HPR primarily due to my electronics background and the fact that if I am going to invest that much in a rocket I don't want to lose it (CATO is understandable but will still bring a tear to my eye). I even completed my HAM technician license just so I could get the Altus TeleMetrum. So this will give me the chance to play with the electronics and I can also use this for electronic ejection in addition to the motor ejection. I also have a little 808 #16 keychain camera that I plan to mount in the top section.

Needless to say that I haven't been this excited in a long time and can't wait to see her fly. I've ordered a CTI H58 White Thunder for the L1 cert flight which will hopefully happen at Southern Thunder in Manchester, TN come June 22nd.

I think I have also come up with a great name for the rocket - The Wife's Despise :lol:
 
Best of luck on your flight!

On some of the smaller tubes, even the Estes, tubes, some good primer really helps on those spirals if your like me and loath that much sanding!! lol

LOVE the name, gonna have to copy that on my scratch build, as that has come to pass for me in the past year...

Kids love it though!
 
With the Ventris you can definitely get away with a small H for certification. It's a pretty slippery rocket with fairly low drag. With a good sized G (99%) we up here found that 2000+ feet is not a problem.
 
You may want top try Bondo spot putty for filling spirals.

I find it to be a much better alternative to sanding sealer.

How was fit of the transition?
Older kits at least had problems with a poor fit.
I ended up returning mine.
I'd like to build one, but only if they have fixed the transition problem.

Bones

Spot putty rs.jpg
 
The fit for the upper tubes is real nice but these will be pinned. The lower tube to the transition is a little loose but I plan to CA the tube and maybe 1 layer of tape should make it real nice.
 
the h54 is a long burn motor and the ventris is pretty skinny and light. I hope you have a lot of room where you launch. and a tracker. :)

good luck!
 
I am going to do my attempt on an H128W. Did a static test for my Ventris the other day with great success. Hopefully the real test goes just as good. lol
 
the h54 is a long burn motor and the ventris is pretty skinny and light. I hope you have a lot of room where you launch. and a tracker. :)

I like the H54 because it is a long burn and low average impulse. RockSim shows that it should reach about 0.6 mach and about 2600 feet. I am praying for little wind, otherwise I am going to be walking a lot! I am putting an Altus TeleMetrum in it to give me tracking so hopefully I don't lose it.

Samurai - I am eager to hear your results - good luck!
 
I like the H54 because it is a long burn and low average impulse. RockSim shows that it should reach about 0.6 mach and about 2600 feet. I am praying for little wind, otherwise I am going to be walking a lot! I am putting an Altus TeleMetrum in it to give me tracking so hopefully I don't lose it.

Samurai - I am eager to hear your results - good luck!

Dido! Dang, if you are expecting 2,600 feet on the H54 what is my H128W gonna hit? I don't have sim yet so you should run it for me. :)
 
Dido! Dang, if you are expecting 2,600 feet on the H54 what is my H128W gonna hit? I don't have sim yet so you should run it for me. :)

Probably a little less. The impulse is about the same, and it has a faster burn.
 
I don't have it in front of me right now but I believe it was between 2200 and 2400. I'll check it out tonight for you.

I've been busy trying to get my electronics bay all put together inside the upper tube and nosecone. Coming together pretty good and I hope to have some pictures up soon. Just waiting on a few last components to show up.

Of course adding the electronics has made my nose heavier and while I still have to account for this in my model, I know that it is going to be very over-stable. Any suggestions on if I should add some weight say between my motor-mount and body tube? I was thinking about drilling a small hole into this section and injecting some glue in order to add mass. What are your guy's thoughts? I hope to have the model updated within the next day or two in order to give some actual numbers.
 
I don't think you should add weight to make it less stable. just leave it as is.

I'd like to see what you came up with for the nose cone bay. I'm working on my ventris now and I want to add a place in the nose cone for my gps tracker.

Thanks!
 
Samurai - my simulation showed 2570 feet for the AeroTech H128W.

Here is a picture of the payload bay and my electronics sled which fits into slots made in both the transition section and the nose cone for a tight and secure fit. The sled holds an Altus TeleMetrum which is wired to one slide switch for on/off control (SPST) and another switch (DPST) is placed in-line for the apogee charge. The small black blob at the bottom of the picture is an 808 keychain camera (#16) which fits in the epoxy clay molds made on the top of the transition section. I made it so the camera can mount to look down at an angle if mounted on one side or it can be mounted to look horizontally from the other side. Unfortunately the down looking position required a much larger hole in the body tube than I really care for but it should work. I've got to take a dremel to remove some of the epoxy clay in order to lower the weight a bit and shorten the screws.

Electronics Bay Seperated.jpg Camera Mount.jpg Electronics Bay Installed.jpg Electronics Bay Closed.jpg

Overall I am pretty happy with it except that when I was drilling the holes for the push rivets I had the sled in place for alignment and accidently ran the drill right into the LiPo battery. :facepalm: That made for some excitement as I quickly cut it out and ran it outside just in case it would catch fire. Luckily no fire but now I get to buy a new battery. By the way, RadioShack will take any damaged LiPo batteries for free and properly recycle them.

Here is an updated picture of my kids with the naked rocket.

Kids with Ventris Raw.jpg
 
Samurai - my simulation showed 2570 feet for the AeroTech H128W.

Here is a picture of the payload bay and my electronics sled which fits into slots made in both the transition section and the nose cone for a tight and secure fit. The sled holds an Altus TeleMetrum which is wired to one slide switch for on/off control (SPST) and another switch (DPST) is placed in-line for the apogee charge. The small black blob at the bottom of the picture is an 808 keychain camera (#16) which fits in the epoxy clay molds made on the top of the transition section. I made it so the camera can mount to look down at an angle if mounted on one side or it can be mounted to look horizontally from the other side. Unfortunately the down looking position required a much larger hole in the body tube than I really care for but it should work. I've got to take a dremel to remove some of the epoxy clay in order to lower the weight a bit and shorten the screws.

View attachment 132263 View attachment 132268 View attachment 132262 View attachment 132261

Overall I am pretty happy with it except that when I was drilling the holes for the push rivets I had the sled in place for alignment and accidently ran the drill right into the LiPo battery. :facepalm: That made for some excitement as I quickly cut it out and ran it outside just in case it would catch fire. Luckily no fire but now I get to buy a new battery. By the way, RadioShack will take any damaged LiPo batteries for free and properly recycle them.

Here is an updated picture of my kids with the naked rocket.

View attachment 132264

Looks great! What did you do for the recovery harness mount?
 
Looks great! What did you do for the recovery harness mount?

Thanks. In the original post I have a picture of how I glued the Estes shock cord to the motor mount and cut ever so slightly a notch in one of the motor mount rings to pass it through. I highly doubt it will come loose from this. I am putting a nomex sleeve (https://www.apogeerockets.com/Build...ock_Cord_Protectors/58in_Shock_Cord_Protector) over the shock cord in order to protect it from the ejection charges. I haven't attached the other end of the shock cord to the transition piece yet but I figured a couple of knots and some adhesive heat shrink should secure it nicely.
 
I think I have also come up with a great name for the rocket - The Wife's Despise :lol:

I've been mulling this one over and despise isn't quite the right word. She tolerates my hobby - with a bit of an eye roll - but she doesn't despise it (unless she knew what I have spent).

Any ideas on a better word choice?
 
Well my wife convinced me that she doesn't find it cute so I am going to go with a phrase that I heard on this forum - "Allergic To Earth".

Painting is currently in progress - oh how I hate painting and it hates me - just not patient enough.

Still waiting on a replacement battery to show up for the Altus TeleMetrum - the clock is ticking for a Southern Thunder flight. I sure hope it shows up soon because I really need to do some ground testing and would like to do at least one test flight with an F motor. I am afraid that my local launch site just isn't big enough for anything else. I am even a little fearful of using an F motor.
 
I completed the paint job - minus clear coat and water slide decals. I like how the fins and body turned out but the purple for the nose section just doesn't work quite right. So I am in the process of repainting the nose section blue like the body. Should turn out real nice.

Painted.jpg
Note that it is still sitting on the paint stand.

Now if I could just get the replacement battery for the TeleMetrum shipped to me...
 
Finished adding all of the parts and balancing/weighing to modify the Rocksim model to account for the actual build weights to determine the true CG and CP.

Total (no engine) weight is 664.5 g or 23.4395 Oz or 1.46 lb with a CG from nose of 27.4642" and a CP of 38.7111".

With the Estes F26FJ-6 the CG moves to 29.58" with a margin of 3.65.
Total mass: 765.2 g
Altitude: 705 feet
Max Velocity: 184 ft/s
Launch rod departure velocity: 31.07 ft/s
Landing: 24.5 ft/s

With the CTI H54W the CG moves to 30.8916" with a margin of 3.13.
Total Mass: 873.5 g
Altitude: 2548 feet
Max Velocity: 452 ft/s
Launch rod departure velocity: 50.73 ft/s
Landing: 26 ft/s

All simulations are for no wind (I wish) with a starting altitude of 1060 ft (Manchester, TN) with 50% humidity.
 
Just completed my first static ejection test. Calculation showed right at 0.40 grams of ffffg black powder so that is what I tried first. Check out the test shot here:

[YOUTUBE]wDRHsBaS2Tc[/YOUTUBE]

I think it worked! Sorry it was already getting dark but you can still see the ejection nicely.

I made the charge using the straw tube method with a Q2G2 igniter.
 
My L1 Cert flight was a total success at Southern Thunder 2013 in Manchester, TN on Saturday. I am working on the video edit and will post it shortly.
 
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