Can Ventris withstand HPR motor?

TheSamurai · Mar 12, 2013

I am thinking of doing a HPR launch this year. Level 1 hopefully. I am almost done with the Estes Pro Series II Ventris. I am going to fly it on the G80-7T. I am wondering if the Ventris can be flown on a lower end H motor or if it is always best to buy another rocket that the manufacturer that says will take an H motor, depending on the motor of course.

I don't know if an H motor will change the CP and CG so that the rocket will be unstable.

Rex R · Mar 12, 2013

from what I've read, some folks have flown them on an I200...finding it afterward might pose problems though

.
rex

TheSamurai · Mar 12, 2013

Rex R said:
from what I've read, some folks have flown them on an I200...finding it afterward might pose problems though .
rex

Well that is a bigger motor than I would have picked but I can imagine that problem of finding the thing after. The Ventris is a pretty heavy beast I am thinking that an H motor isn't going to carry it to far away from me. Money is pretty tight and I really want to get my L1 Cert. done this year. While I would love to just go out and buy another rocket, the old lady and I are in agreement that we have to watch the budget. My family and I are just one of the few affected by the sequester.

Rex R · Mar 12, 2013

while I'm in the camp of building a dedicated bird...I can relate. a larger diameter rocket would stay lower, an example would be the leviathan(a 40% off coupon at hobby lobby...).
rex

BEC · Mar 12, 2013

I am sure the Ventris can do it. A baby H would put it up to at least 2500 feet....so plan accordingly. That's why I built a slightly heavier and draggier Leviathan for my L1 cert.

(Rex, both the Ventris and Leviathan are carried by HL and so both can be had with 40% off coupons. That's how I got both rockets myself.)

samb · Mar 12, 2013

Well heavy is a relative term, eh ? None of the pro series models are that heavy compared to some the 3 and 4 inch LOC, PML, and Madcow 38mm models that you could choose for a level 1 flight. I agree that you can build the airframe to withstand an HPR boost without getting too exotic with the construction. As for recovery, maybe you have some wide open spaces in Caldwell ! One thing about the design of the Ventris that other have mentioned as a typical failure point on level 1 attempts: models with fins swept back behind the body can be susceptible to breaking on landing. Good luck with whatever you fly and whenever you decide to go for it.

Rex R · Mar 12, 2013

took me a bit to recall which two pro series birds HL carried

, my usual shop (not HL) carries all of them(including the MDRM, which would be perfect).
rex

mcderek · Mar 12, 2013

My sons stock Ventris has flown on G54, G114 and H90. Flies great! And gets up there

TheSamurai · Mar 12, 2013

samb said:
Well heavy is a relative term, eh ? None of the pro series models are that heavy compared to some the 3 and 4 inch LOC, PML, and Madcow 38mm models that you could choose for a level 1 flight. I agree that you can build the airframe to withstand an HPR boost without getting too exotic with the construction. As for recovery, maybe you have some wide open spaces in Caldwell ! One thing about the design of the Ventris that other have mentioned as a typical failure point on level 1 attempts: models with fins swept back behind the body can be susceptible to breaking on landing. Good luck with whatever you fly and whenever you decide to go for it.

Well I epoxied the fins on so hopefully that won't be a problem. lol

We have a TON of BLM land out here. Space is not a problem. I'll just run and catch it out of mid-air. Is that allowed on a cert.? :lol:

samb · Mar 12, 2013

TheSamurai said:
... I'll just run and catch it out of mid-air. Is that allowed on a cert.? :lol:

As a matter of fact, No, if you're going by NAR rules:

https://www.nar.org/NARhpsc.html

...
13. Recovery Safety. I will not attempt to recover my rocket from power lines, tall trees, or other dangerous places, fly it under conditions where it is likely to recover in spectator areas or outside the launch site, nor attempt to catch it as it approaches the ground.

I encourage the aerobic activity if you're up for it. But I don't think NAR insurance will cover any mishap from over exertion :grin: .

I'll leave it to you to check with Tripoli if that's who you will cert with.

TheSamurai · Mar 12, 2013

samb said:
As a matter of fact, No, if you're going by NAR rules:

https://www.nar.org/NARhpsc.html

...
13. Recovery Safety. I will not attempt to recover my rocket from power lines, tall trees, or other dangerous places, fly it under conditions where it is likely to recover in spectator areas or outside the launch site, nor attempt to catch it as it approaches the ground.

I encourage the aerobic activity if you're up for it. But I don't think NAR insurance will cover any mishap from over exertion :grin: .

I'll leave it to you to check with Tripoli if that's who you will cert with.

Oh I have no intention of doing any running. lol.

dcbertelsen · Mar 12, 2013

The Ventris works well on H-impulse motors. My son earned his Jr. Level 1 Certification last October on one. First flight was a CTI H87 (IMax) which ended in a popped fin. Second flight was a CTI H133 (BlueStreak) which was successful. Those flights were near the 2000 ft range if I remember. In sight for the full flight but drifted quite a long distance. He did add rail buttons, Kevlar shock cord mount, and beefed up the shock cord. Epoxy fillets (clay, which I will never use on fillets again) to keep fins on were the only external change.

Short answer: Go for it!

With RDF this season, I may talk him into an I.

Green Jello · Mar 12, 2013

dcbertelsen said:
The Ventris works well on H-impulse motors. My son earned his Jr. Level 1 Certification last October on one. First flight was a CTI H87 (IMax) which ended in a popped fin. Second flight was a CTI H133 (BlueStreak) which was successful. Those flights were near the 2000 ft range if I remember. In sight for the full flight but drifted quite a long distance. He did add rail buttons, Kevlar shock cord mount, and beefed up the shock cord. Epoxy fillets (clay, which I will never use on fillets again) to keep fins on were the only external change.

Short answer: Go for it!

With RDF this season, I may talk him into an I.

That's odd. I have 3 flights on my Ventris, all with G64-7W and they average around 2100' on it.

dcbertelsen · Mar 12, 2013

Maybe it was 2600 and 2800 feet (less with wind). I don't have his sim data on hand at the moment. He did leave the upper payload section unglued for an altimeter. Oh the plans!

Green Jello · Mar 12, 2013

Well, I guess I also launch from 4500' elevation.

TheSamurai · Mar 13, 2013

Thank you all for your responses. Sounds like it won't be a problem using the Ventris for my L1.

Derek · Mar 13, 2013

dcbertelsen said:
The Ventris works well on H-impulse motors. My son earned his Jr. Level 1 Certification last October on one. First flight was a CTI H87 (IMax) which ended in a popped fin. Second flight was a CTI H133 (BlueStreak) which was successful. Those flights were near the 2000 ft range if I remember. In sight for the full flight but drifted quite a long distance. He did add rail buttons, Kevlar shock cord mount, and beefed up the shock cord. Epoxy fillets (clay, which I will never use on fillets again) to keep fins on were the only external change.

that does seem low. my ventris with a f26 goes over 1000'. That falls in line with green jellos's 2100' g64.

is it really heavy?

mcderek · Mar 13, 2013

TheSamurai said:
Thank you all for your responses. Sounds like it won't be a problem using the Ventris for my L1.

No, you won't have any problem at all! The Estes Leviathan is one of the best Level 1 birds out there. We've had 3-4 people get there Lv. 1 with it at our club.

kelltym88 · Mar 13, 2013

FWIW, I cert'd L1 on my NorthCoast Interceptor G on an H97.... I would think even a stock Ventris could handle that......

TheSamurai · Mar 13, 2013

mcderek said:
No you won't. The Estes Leviathan is one of the best Level 1 birds out there. We've had 3-4 people get there Lv. 1 with it at our club.

Thanks. I sure hope it works out. All I have left to do is calculate the CP and I will be good to go. Gonna launch it on my G80-7T first. Break in her in before I do the L1.

cerving · Mar 13, 2013

I'd avoid going above 200NS average thrust, but other than that it's a good L1 bird.

TheSamurai said:
I am thinking of doing a HPR launch this year. Level 1 hopefully. I am almost done with the Estes Pro Series II Ventris. I am going to fly it on the G80-7T. I am wondering if the Ventris can be flown on a lower end H motor or if it is always best to buy another rocket that the manufacturer that says will take an H motor, depending on the motor of course.

I don't know if an H motor will change the CP and CG so that the rocket will be unstable.

Derek · Mar 13, 2013

cerving said:
I'd avoid going above 200NS average thrust, but other than that it's a good L1 bird.

so a h410 is out? boooo!

TheSamurai · Mar 13, 2013

cerving said:
I'd avoid going above 200NS average thrust, but other than that it's a good L1 bird.

Thanks for the advice. I was going to choose a lower end H motor anyway for the first attempt.

Green Jello · Mar 13, 2013

All this talk about big motors in the Ventris got me wondering.....

I can't remember if I installed the engine blocks in my Ventris and Leviathan or not. I'll have to check that when I get home. I may need to pick up a 6 grain CTI case.

cerving · Mar 13, 2013

You can try it, but I don't know if the Estes ProII tubing will be able to take it. That's about 50:1 thrust/weight ratio, a bit high for cardboard.

Derek said:
so a h410 is out? boooo!

TheSamurai · Mar 13, 2013

Are a lot of the H motors 29mm?

The Ventris motor retainer set is made for 29mm I believe. Is the length of the H motors longer than my G80-7T but has the same diameter?

Green Jello · Mar 13, 2013

There are even some 29mm I motors. For example, here are the CTI 29mm:

https://www.wildmanrocketry.com/ShowProducts.aspx?Class=754&Sub=795

Derek · Mar 13, 2013

TheSamurai said:
Are a lot of the H motors 29mm?

The Ventris motor retainer set is made for 29mm I believe. Is the length of the H motors longer than my G80-7T but has the same diameter?

yes. I hope you didn't install the motor block in the motor mount tube.

CarVac · Mar 13, 2013

TheSamurai said:
Are a lot of the H motors 29mm?

The Ventris motor retainer set is made for 29mm I believe. Is the length of the H motors longer than my G80-7T but has the same diameter?

As far as I know, currently available H motors are all either 29mm or 38mm. In 29mm, I believe that every single H is longer than the single-use G80T. The Aerotech G138T is almost an H, but it's the same length as the G80.

Derek · Mar 13, 2013

Green Jello said:
All this talk about big motors in the Ventris got me wondering.....

I can't remember if I installed the engine blocks in my Ventris and Leviathan or not. I'll have to check that when I get home. I may need to pick up a 6 grain CTI case.

a six grain case will hit the baffle in mine.

too bad as it would be a really good test for my tracker!

Can Ventris withstand HPR motor?

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