Gizmo for L1? OR A RW LIL RASCAL

[Wiley]

I know that Gizmos get flown a lot on I motors, but I was wondering if it can be done with a baby H for a L1 cert. If the rocket was built light with Aeropoxy ES6209 and a minimum of hardware, would an H128-S put it up high enough for a safe flight? I know that most people brutally overbuild these things to stuff K motors into them, but I guess what I'd like to know is if it is possible to achieve the 3-4# advertized built weight.

 

[patelldp]

I know that Gizmos get flown a lot on I motors, but I was wondering if it can be done with a baby H for a L1 cert. If the rocket was built light with Aeropoxy ES6209 and a minimum of hardware, would an H128-S put it up high enough for a safe flight? I know that most people brutally overbuild these things to stuff K motors into them, but I guess what I'd like to know is if it is possible to achieve the 3-4# advertized built weight.

You could easily tack all components and do minimal fillets with 5 minute epoxy. You'd add a couple of ounces to the raw weight of the materials.

Add in a 1/4" Kevlar shock cord, a 45-50" parachute, and a Nomex protector and you'll be fine. You could probably even leave out the nosecone bulkhead to save an ounce or two.

I don't know what the raw material weight would be, but if it's 4-5 lbs I am not sure if an H128W would do it. I flew my 4" LOC Bullet on an H238T last weekend and it weighed 2.5#. It had a Featherweight Parrot V2 in a hatch between the fins and only flew to 1,700'. If you were you double that weight I'd imagine it would be a marginal flight. An H238T is a better choice than the H128W for this application, and the H220T or H250G in the 29-240 case are even better yet.

 

[gdiscenza]

I don't know if there is any prohibition against certifying L1 with an I motor, you might explore that for a Gizmo cert flight.

G.D.

 

[chadrog]

I don't know if there is any prohibition against certifying L1 with an I motor, you might explore that for a Gizmo cert flight.

G.D.

None at all (with NAR anyway). If I remember right, the Giz has a 54mm hole - a single grain 54 "I" motor in a Gizmo would be a great L1 combo! I'd go with an I170G, myself. Why do you feel that you have to use an H128?

 

[Wiley]

Chadrog, because I already have it and the case, and if my cert is successful, I get both for free.

 

[chadrog]

Chadrog, because I already have it and the case, and if my cert is successful, I get both for free.

That makes sense. To maintain the "safe" thrust to weight ratio of 5:1 with the H128, you'd need to keep the (fully loaded) weight of the rocket under 5.75 pounds. Might be tough, that thing probably needs a fair amount of nose weight too.

 

[Wiley]

Good point Chadrog. It shouldn't be too hard to keep it that light, since the parts only weigh 3#.

This is for all you folks out there that have a Gizmo. Where does the CG of the fully loaded rocket need to be in order to have a stable flight?

 

[chadrog]

Good point Chadrog. It shouldn't be too hard to keep it that light, since the parts only weigh 3#.

This is for all you folks out there that have a Gizmo. Where does the CG of the fully loaded rocket need to be in order to have a stable flight?

I don't have one, but this info on rocketreviews looks convincing: https://www.rocketreviews.com/performance-rocketry-gizmo-6166.html

 

[Wiley]

So I take it that a CG 19" from the nose tip will keep it properly stable, correct? Crazy Jim's input would be greatly appreciated here.

 

[GRIFFIN]

Crazy Jim has never had a Gizmo in one hand and an H motor in the other !! Lol!!!!!

 

[gregm]

The Gizmo will fly like crap on an H128. It did terrible on an I229T (AT) and equally bad on a I455V (CTI).

You need something like an I800V or more. It took flying mine on a J1055V to get a nice flight (although I didn't try the I800). Needed nose weight no matter what and it will not end up light. With a J1055V is was 7 pounds on the pad.

 

[Wiley]

It depends what you mean by "fly like crap." I don't like super high or fast flights, especially on a motor-eject design. I fly my 3# AT Sumo all the time on G64s, and it goes maybe 500 feet. This would be the kind of flight I'd expect from my Gizmo. Also, the J1050 weighs 1.7#, so your rocket only weighed 5.3# without it.

 

[blackjack2564]

Crazy Jim has never had a Gizmo in one hand and an H motor in the other !! Lol!!!!!

OH YE OF LITTLE FAITH!

My maiden flight was the soda can motor I-229-T drag race.[which I won by the way.lol]

Followed by.......wait for it............. H-250......Yep H H H H H! But I only did that once, just to say I did. Both on fairly calm days. Yeah I usually do something silly like a V-max 3-4 grain, with a 300ft streamer & 24in X-chute. 7 sec delay on both.[the H & I ]

I have never seen one under 6.5lbs....mine weighs 7.5 which is typical[7.5-8.5 you will need nose weight] I only used .75lb cause I knew it would fly on either small or big.....in between is where you get in trouble. Wishful thinking to get under 6.

It's a very draggy rocket, so you need to respect that. Your asking for trouble using H-128

Why don't you stick it in the sumo?
Only around 1000ft flight. You could always add a payload to it for very little cost. That would be the down and dirty way around it.

 

[blackjack2564]

This is what you stick in a Gizmo!

But then no way the NC will fit. you have to improvise! Yes I have done this on more than one occasion.


Here is my NC weight. Needed more.....so there are metal tent stakes, allen wrenches, threaded rod filled with nuts & anything else I could lay my hands on at the time to make it stable. Cut out in foam & hole next to NC wall are for tracker & antenna.



Chute never gets hung up and there are NO fillets, just foamed the fins on.

 

[Wiley]

CJ, now that you mention it, you are correct. I'll use the Sumo for my L1, and build the Gizmo later. How much altitude did you get with the H250, and do you think it would be safe to fly on an H180? It looks like your NC bulkplate is located about where the top of the shoulder is. Is this correct?

 

[Sgt Blowfly]

I built mine heavy at 6.50 lbs w/o motor (added some nose weight to move CG up a bit.)
With an I300 (my favorite motor for this bird) it weights about 7.50 lbs and CG is just at 19 inches.

Bob
TRA6797

 

[bill2654]

I dont see any way you can keep from adding nose weight for stability/saftey reasons. I built both mine stock and they come in at 6.75 lbs loaded. I added 12 oz of nose wieght and another 12oz of foam. I300's are my favorite for now but I'm installing an altimeter in the NC so I can go higher. If I had to sell off every rocket I had, I would keep my Gizmo!

 

[cbrarick]

+1 on the nose weight. You're gonna need a lot to get that H motor to fly straight. I also agree with the I statements.
My gizmo doesn't have nose weight but I fly mine on the K2045 Vmax so it's long enough to fix the stability problem and enough push to make it go straight (it really doesn't have a choice)

 

[gregm]

You are right, mine only weighed 5.3# without the motor. "flies like crap" = never straight, severe direction change off the rail (except on the J1055). Last flight, the I455, was enough for ejection to violently break loose the weight in the nose cone.

You need a Mini Magg not a Gizmo. Built stock it will fly fantastically on a G or small H.

 

[Wiley]

So, any of the I motors in the 38/360 case should would work nicely, right, or is the 480 case better suited?

 

[gregm]

Except for the Warp9's the rest will fly poorly.

I'd suggest flying something very fast, like the I1299, to get your cert out of the way. Then play around with other motors.

 

[Wiley]

What about the Rocketry Warehouse Lil Rascal? It looks similarly proportioned to the Gizmo, but I can't find any specs for it (nor do I have Rocksim). It looks like 4" airframe with a 54 mm hole. I think the fins are 3/32, and if they are, I could easily cut out some 3/32 G10 Gizmo fins scaled to fit it.

 

[GRIFFIN]

I have flown my RW L rascal on high impulse G motors. H motors would be fine. Nose weight on mine was about a pound.

 

[Rrwjr]

What about the Rocketry Warehouse Lil Rascal? It looks similarly proportioned to the Gizmo, but I can't find any specs for it (nor do I have Rocksim). It looks like 4" airframe with a 54 mm hole. I think the fins are 3/32, and if they are, I could easily cut out some 3/32 G10 Gizmo fins scaled to fit it.

If you go to my build thread located here: https://www.rocketryforum.com/showt...components-to-the-Launch-Pad&highlight=Rascal you will find roc sim file of orginal as well as roc-sim of what I built. Love the rascal.

 

[Wiley]

Thanks for the help guys, I just have a couple more questions and then I should be good to go. Could any of you with Rocksim post an exact scale drawing of the Gizmo's fin profile? I would also like to know how far up on the tube the fins are mounted. These two bits of information should be all I need to make a nice downscale Gizmo. Thank you!

 

[Rrwjr]

My Lil rascal which I reference in above post weighs in at 5 pounds. I did run a sim on it with the H238. Assuming you can get adaptor from a 54mm to a 29mm it will fly stable. I used a 6 second delay in 8 to 14 mile an hour winds with partly cloudy condtions at 32 degrees fahrenheit. THis was off a 72 inch long rail as well.
If you live in Wisconsin or Illinios and are going to Bong this weekend, the above is what our weather is looking like.

 

[Wiley]

I live in eastern Washington State. Out here in the desert we usually have a lot less wind and more clear days. The Lil' Rascal is a 4" rocket right? I still need to have the dimensions I requested in post #26. Thanks again!

 

[Rrwjr]

I live in eastern Washington State. Out here in the desert we usually have a lot less wind and more clear days. The Lil' Rascal is a 4" rocket right? I still need to have the dimensions I requested in post #26. Thanks again!

Yes the Lil Rascal is a 4 inch rocket. Cant help you on the fins as I dont have a Gizmo and I have found a lot of roc-sim files arent correct that are online. I use them for reference and tweak them to the actual kit when i have it.

 

[GaryT]

I'd recommend you buy Rocksim, calculate where the Cp is on either of the rockets, then determine where you! want the Cg to be to net a stable flight.

 

[Wiley]

I have Openrocket, and it has been adequate for my needs. I just wanted to know the exact fin shape so my rocket would look exactly the same as the full size version. Thanks!