Hi Tech / Low Power?

[DJRNY]

Hello,
I am nearing completion of a LOC Hi Tech H45. The first opportunity I will have to fly it is on some smaller fields. So for those who also fly the Hi Tech rocket, I am wondering what is the smallest motor you have used for a successful flight (and the altitude)?

OK, I know, sort of the opposite question that most people ask.......

Dave

 

[David_Stack]

You can download Open Rocket, upload the sim file from the Loc site, adjust the model as necessary to match the weight of your built model, and then run any number of simulated flights using a variety of motors.

The simulations will provide you data on speed off the rail, maximum altitude, recommended delay, etc.

Or you can go to the Thrustcurve site, enter in the parameters for your rocket, and generate similar data.

 

[Art Upton]

Hello,
I am nearing completion of a LOC Hi Tech H45. The first opportunity I will have to fly it is on some smaller fields. So for those who also fly the Hi Tech rocket, I am wondering what is the smallest motor you have used for a successful flight (and the altitude)?

OK, I know, sort of the opposite question that most people ask.......

Dave

In the late 1980s I flew mine on a F41-or F50 type motors ; can't remember what

 

[Scott_650]

Or you can go to the Thrustcurve site, enter in the parameters for your rocket, and generate similar data.

Another upvote for TC, it works well on typical 3/4FNC designs - on more complex designs it’s not as accurate as a sim in Open Rocket or RockSim but for rule if thumb motor choices TC is close enough.

 

[DJRNY]

Art Upton - thanks. I'm guessing that asking you about altitudes would be stretching it..... Ha!

David Stack / Scott 650 - Thank you. I am aware of some of the simulation programs out there, and use TC a lot. However, I was fishing for real data. I thought there must be people out there who launched a Hi Tech on lower power motors. At least once!

 

[David_Stack]

Good Morning DJRNY;

The only 'firm' data I could find in a search of the forum is this post:

https://www.rocketryforum.com/threa...-flown-mid-power-at-home.162133/#post-2051154
You'll note the reference to 800' - 1000' on a G, not sure if that aligns to your definition of lower power...

 

[Art Upton]

Art Upton - thanks. I'm guessing that asking you about altitudes would be stretching it..... Ha!

David Stack / Scott 650 - Thank you. I am aware of some of the simulation programs out there, and use TC a lot. However, I was fishing for real data. I thought there must be people out there who launched a Hi Tech on lower power motors. At least once!

My "guess" from back then was 500-600 feet.

 

[Back_at_it]

Hello,
I am nearing completion of a LOC Hi Tech H45. The first opportunity I will have to fly it is on some smaller fields. So for those who also fly the Hi Tech rocket, I am wondering what is the smallest motor you have used for a successful flight (and the altitude)?

OK, I know, sort of the opposite question that most people ask.......

Dave

When finished, Mine weighted in at 21.2oz loaded minus the motor. I've flown it twice on the F44-4 which is about the smallest motor I'm willing to attempt. I've never done an altimeter flight but my guess is the apogee was right at 500ft. It's a heavy rocket so it recoverys quickly on the included parachute. It also flies very well on the F67-6 but you're pushing 1000ft with that motor.

It's worth noting that I built mine with a 29mm mount permanently mounted inside the 38mm tube. I didn't see the point of the 38mm mount as I have no where to fly that sized motor on this small of a rocket.

 

[DJRNY]

Good Morning DJRNY;

The only 'firm' data I could find in a search of the forum is this post:

https://www.rocketryforum.com/threa...-flown-mid-power-at-home.162133/#post-2051154
You'll note the reference to 800' - 1000' on a G, not sure if that aligns to your definition of lower power...

Thanks David. I missed that thread, but did find another which mentioned flying a Hi Tech on G motors (G40, G80) to just over 1000'. Tat might be a little high for my location but is good information.

Dave

 

[DJRNY]

When finished, Mine weighted in at 21.2oz loaded minus the motor. I've flown it twice on the F44-4 which is about the smallest motor I'm willing to attempt. I've never done an altimeter flight but my guess is the apogee was right at 500ft. It's a heavy rocket so it recoverys quickly on the included parachute. It also flies very well on the F67-6 but you're pushing 1000ft with that motor.

It's worth noting that I built mine with a 29mm mount permanently mounted inside the 38mm tube. I didn't see the point of the 38mm mount as I have no where to fly that sized motor on this small of a rocket.

Thanks, this is perfect! 500' is in the ball park of what I'd like to do for my first flight. It is also good to know it drops fast on the supplied chute.

Mine is actually a bit heavier than yours, weighing in at 22.7 oz before painting. It is my first mid-high build so I probably went overboard with the epoxy! That weight also includes a motor retainer and a 29/38 motor adapter, although mine isn't permanently mounted.

Dave

 

[Ronz Rocketz]

This one? Both on the E24-4C. Helen likes them low and slow. I'm not sure why the first launch was longer than the second.

 

[DJRNY]

Nice! Low and slow works for me! E24-4C? Wow, I hadn't considered anything smaller than F. I'll add it to my list! Thanks!

 

[Art Upton]

This one? Both on the E24-4C. Helen likes them low and slow. I'm not sure why the first launch was longer than the second.

My First Hi-Tech 45 I lost on the F motor when it landed in a fenced in area I could not get it back out of. I heard in the video the second one someone said "Just over the fence". Did you get it back?

 

[jmasterj]

However, I was fishing for real data. I thought there must be people out there who launched a Hi Tech on lower power motors. At least once!

You got one reply that included weight - without that data plus your own rocket's weight, people's anecdotes aren't particularly useful to determine what motors you can fly your Hi-Tech on.

 

[Ronz Rocketz]

My First Hi-Tech 45 I lost on the F motor when it landed in a fenced in area I could not get it back out of. I heard in the video the second one someone said "Just over the fence". Did you get it back?

Here's the deal. The winds were mild under 5mph. Usually the trade winds are under 10mph and push rockets into the open area. Instead, we had about 5 rockets land in the gated construction area. They've been nice about it in the past, Fortunately, we were able to open the gate this time. Next time we launch there in low winds, we'll have to set up further south away from the construction yard.

 

[DJRNY]

You got one reply that included weight - without that data plus your own rocket's weight, people's anecdotes aren't particularly useful to determine what motors you can fly your Hi-Tech on.

A valid point. The data are incomplete, and also rather sparse. I was hoping more people would weigh in.
The one weight that was posted is on the order of 7% lower than my Hi Tech. A quick comparison using TC shows that the difference in apogee is on the order of 7%. For my immediate interest I am not concerned about the difference between 500' and 550', but interested in getting a feel for 500' Vs 50'.
There are a lot of variables. Weight is certainly one of them. Has anyone ever done a Monte Carlo analysis including all the major variables? That might be interesting.

Not to hijack this thread, but for a kit build, following instructions (e.g. not doing anything drastically different), what is the variation in weights of the completed rocket? Maybe people could post the weight of their Hi Tech, even if the altitudes of various flights on known motors aren't known? Or has anyone ever looked at this for another popular kit?

Oh, wait, this is my thread. In that case, can I really hijack it?

Dave

 

[GalantVR41062]

Open rocket.

It's a great simulation software, it's as good as the information you input.

I don't have a Hitech 45, wanted one for a bit. I have other 2.5" diameter park flier rockets, a Jolly logic chute release fits easily in the air frame.

 

[kjhambrick]

All'y'All made me look.

The model came from LOC's PK-56-Hi-Tech-H45.zip file, imported into OpenRocket.

I adjusted the dry mass to 22.7 oz / 645 grams by moving LOC's Mass Object to the position of the No Motor CG and then setting it to 96 grams.

An F44 looks 'nice and low but not too slow' ...

.

The .ork is attached as well.

Whee !

-- kjh

 

[Back_at_it]

Looks good. The F44 really is a great motor for heavier rockets that you don't want to go super high. Lots of thrust off the pad but a very short burn time.

I have safely lifted a 4in Maxi Streak Upscale that weighted 28.2oz loaded without motor off a 6ft 1/4" rod with no issues. It really is a great motor.

 

[kjhambrick]

Looks good. The F44 really is a great motor for heavier rockets that you don't want to go super high. Lots of thrust off the pad but a very short burn time.

I have safely lifted a 4in Maxi Streak Upscale that weighted 28.2oz loaded without motor off a 6ft 1/4" rod with no issues. It really is a great motor.

Good catch, @Back_at_it !

I neglected to mention that I 'flew' the Hi-Tech on those motors from a 60-inch rail in a 10 mph wind at 60 F and at 640 ft MSL ...

I always liked that rocket

-- kjh

 

[DJRNY]

An F44 looks 'nice and low but not too slow' ...

The F44 really is a great motor for heavier rockets that you don't want to go super high

I 'flew' the Hi-Tech on those motors from a 60-inch rail in a 10 mph wind at 60 F and at 640 ft MSL ...

Thanks! It looks like the F44 is a good choice for what I am seeking.

But now the rookie question: My Hi Tech has a 38mm mmt and an Aero Pack 38mm retainer. The F44 is a 24mm motor, and I cannot find a 24mm/38mm motor adapter anywhere. Does anyone know where I can get one that I may have missed in my searches?

What I have found is reference to using an AeroPack 24mm/29mm adapter inside an AeroPack 29mm/38mm adapter, or building one yourself. Has anyone used an AeroPack 24/29 nested inside a 29/38?

For building one myself, I cannot find 24mm to 38mm centering rings. I assume then I could use 24mm to BT60 centering rings and sand them down, use one not sanded (or sanded less) at the aft end and maybe an 18mm to BT60 sanded to fit for the end cap. Or is it better to use the green paper centering rings and put a 24mm/29mm centering ring inside a 29mm/38mm centering ring to "build" a 24/38 centering ring? How have others done this?

Thanks,
Dave

 

[kjhambrick]

Dave --

If you're flying the F44 in the Hi-Tech, mass is not your friend.

I would say design and build a 24-38 mm adapter and make it as light as you can without sacrificing strength.

That F44 will accelerate your rocket at about 8.5 G so your 24-38 mm adapter will need to lift 193 oz / 12 lb !

I like your idea of making the outer aft C-Ring the same OD as an RMS 38 aft closure so it works in your AeroPack.

That idea is a keeper !

Watch your weights -- the pad-mass of your rocket WILL be more than 22.7 oz !

That always happens somehow

There is a 96 gram OR Mass Object in the 2nd Body Tube located at 28 inches along the airframe.

Load your rocket as though it is ready for flight and weigh it and find the CG.

Adjust the 96 gram Mass Object and make sure that the CG is 'close' and then rerun the sims.

You might find that the F44 is too low AND too slow for a successful flight ... then again it might be just fine ...

HTH and good luck !

-- kjh

EDIT: p.s. If you fly a small motor, do try to be sure you've got enough BP in the ejection well to pop the payload section off the booster at apogee !

 

[kjhambrick]

Dave --

You made me look again

Always Ready Rocketry sells Blue Tube 2.0 38mm couplers: ARR - Blue Tube 2.0

I learned that from @augendoc's spreadsheet in: Where to post spreadsheets for body tube and centering ring dimensions?

I will need a 24/38 mm adapter myself for a new Mach 1 BT60 rocket with a 38mm motor mount so you sent me on a hunt

I have not found any 24/38 centering rings either but I'll make a pair from 0.1 inch plywood or from BT-60 / BT-50 rings as you mentioned above.

HTH

-- kjh

 

[Rocketclar]

I've had one for a number of years. Weight about 22 oz (I tend to overbuild). Looking at my logged Excel data, for a F42-4W it went about 521'. F52-5 gave 777', and F60-7 went to about 875'. A G38-7 took it to about 966'. A F39-6 had too long of a delay so I got a slight zipper.

 

[kjhambrick]

Good info @Rocketclar !

Nice thing about the F42T and the F52T is they are 29mm motors so no issues with a 24-38 mm adapter

I can't find the F60 in OpenRocket but I am probably doing it wrong ...

Thanks !

-- kjh

 

[BigMacDaddy]

FWIW - if you really like the design you could always clone it with lighter weight BT-80 tubes and launch on a wider range of LPR motors.

 

[cls]

G61 (and G67) is a nice 1 grain 38mm motor. I burn a lot of those on small fields because I'm too lazy to use the motor adapters.

 

[Rocketclar]

I can't find the F60 in OpenRocket but I am probably doing it wrong ...

Oh, I went back and looked at my data and saw that the F60-7 was a Road Runner motor. Got those from a couple of vendors at AARG launches years ago. RR had a series of mid power motors that I flew regularly.

 

[DJRNY]

I've had one for a number of years. Weight about 22 oz (I tend to overbuild). Looking at my logged Excel data, for a F42-4W it went about 521'. F52-5 gave 777', and F60-7 went to about 875'. A G38-7 took it to about 966'. A F39-6 had too long of a delay so I got a slight zipper.

Now this is what I'm talking about! Thanks!

 

[DJRNY]

Nice thing about the F42T and the F52T is they are 29mm motors so no issues with a 24-38 mm adapter

kjhambrick - thanks for all the info, I appreciate it. But this, just when I convinced myself I HAD to build a 24mm/38mm adapter? I guess I am surprised there isn't one readily available. I already have a couple F42T's to fly it on so I guess I don't really need to build an adapter. But on the other hand, I can......

Dave