X-Plane SST: Scratch Build

I have never scratch built a rocket.

I have built and flown 4" LOC V2 and PML AGM-256 Pit Bull. And am in the middle of building the Sirius Sat V (Build Thread to restart this eve!), and PML 4" Patriot.

For my next project I want to try something new and different.

Hopefully my design sketch will upload...

The basics of the 1st draft design are:

X-Plane SST
4" x 42" Body Tube (90% certain FG)
5:1 FG Nosecone (20")
3 tail fins
2 wings
2 engine cluster. 29 MMT. (the reason for the cluster is my local field allows up to G's. As well as trying a cluster will be new / exciting)

Before I order any parts,... anyone have any thoughts / warnings?

I don't have any sim s/w. Is this remotely stable? I have no issue with adding a reasonable amount of nose weight (say 8-12 oz). But if it takes 2kg in the nose to make it stable...

I have always been interested in the x-15 style rockets. I took your information and put it into Open Rocket. OR says its 0.93 cal stable with a pair of H128s with no added nose weight. This assumes a FG nose & tube, and 1/8 plywood fins/wings. Some will say that they need to be thicker, and they are probably correct. If you don't have Open Rocket, I highly encourage you to download it and learn to use this free design software.

Terry

View attachment XPlane-SST.pdf

View attachment XplaneSSt.ork

T-Rex said:

I have always been interested in the x-15 style rockets. I took your information and put it into Open Rocket. OR says its 0.93 cal stable with a pair of H128s with no added nose weight. This assumes a FG nose & tube, and 1/8 plywood fins/wings. Some will say that they need to be thicker, and they are probably correct. If you don't have Open Rocket, I highly encourage you to download it and learn to use this free design software.

Terry

View attachment 91917

View attachment 91918

Click to expand...

Terry, Thank you very much. I didn't even know open rocket was free! I was concerned about buying Rock Sim and making a mistake,... not even knowing the answer was garbage!

I downloaded OR. Pretty easy to get started. Here's my effort. No motors,... but a chute and I put 8 oz 1" back from there tip of the nose cone... pretty good numbers.

Looks feasible.

As you summized,... the X-15 is the inspiration. I went with 3 tail fins as I like the look of 2 wings / 3 fins resulting in drooping stabilizer. It also lets me mount my launch lugs midline on the underside... less obtrusive on the design,... perhaps suggesting it is launched inverted from the underbelly of a mothership.

Thanks for your help!

Simon

No one else interested enough to post?

Quaranta said:

No one else interested enough to post?

Click to expand...

Im very interested.
Thing is,I dont do simulators and Im a LPR and some MPR builder.
Ill let the people that build rockets this size chime in on suggestions on your build.
However,I will say,"I do like the looks of this very much"
Good job on the design.

Thanks for the response.

I've pretty much decided to go ahead with it. I'm going to contact Wildman / Tim tomorrow... see if he'll slot a 4' FG tube for me (not sure if he offers this service!)... if not I'll prob go to PML. Having a pro with the proper equipment slot the tubes will ensure the fins/wings are parallel to the rocket axis.

Quaranta said:

Thanks for the response.

I've pretty much decided to go ahead with it. .

Click to expand...

COOL
Throw your hat over the fence and order the stuff.

Hell yeah!!

After watching, and watching, your Sirius Saturn build I am stoked on this one!!

Wish I had more input, sorry more focused on my current L2 build...lol

Spooks said:

Hell yeah!!

After watching, and watching, your Sirius Saturn build I am stoked on this one!!

Wish I had more input, sorry more focused on my current L2 build...lol

Click to expand...

Thanks for the response and encouragement!

FYI, The Sat V thread has returned as I finish the pre-priming filling / sanding. Hope to begin paint this week... Here's the link:

https://www.rocketryforum.com/showthread.php?34885-Sirius-Saturn-V-Build-Thread

As for this project, I have updated the design. Originally I was going with a 42" BT,... but have increased it to 48". This way, I need much less nose weight for my max planned engine (2x H399 or similar). Much better stability.

With the update, the name has changed to X-Plane HST.

Cant wait to see the glue start flying! Subscribed.

qquake2k said:

I like it! I've always liked the looks of the X-Planes. You mentioned flying it on a G cluster, because your local field only allows G's. Keep in mind a G cluster will probably be a high power flight due to the combined propellant weight. You might want to check with your club first, and make sure they would allow it.

Click to expand...

Good advice to check. I will.

from the NAR website:

NAR said:

Where Is The Line Between Model and High Power Rocketry?

A rocket exceeds the definition of a model rocket under NFPA 1122 and becomes a High Power rocket under NFPA 1127 if it:

Uses a motor with more than 160 Newton-seconds of total impulse (an "H" motor or larger) or multiple motors that all together exceed 320 Newton-seconds
Uses a motor with more than 80 Newtons average thrust (see rocket motor coding);
Exceeds 125 grams of propellant
Uses a hybrid motor
Weighs more than 1,500 grams including motor(s); or
Includes any airframe parts of ductile metal.

Click to expand...

2 x aeotech g79's come in under the 125g propellant mass limit, so I'm OK there. I'm also OK by total impulse.

Weight,... that's way over,... but I think that is OK. But definitely will check.

Good advice! Thanks.

Wildman Tim has his own tube slotting machine. I would think he would do it for you.
GP

Good to know. I sent him an e-mail,... but I think his e-mail filter considers me SPAM. :sad:

I'll give him a call tomorrow.

qquake2k said:

I like it! I've always liked the looks of the X-Planes. You mentioned flying it on a G cluster, because your local field only allows G's. Keep in mind a G cluster will probably be a high power flight due to the combined propellant weight. You might want to check with your club first, and make sure they would allow it.

Click to expand...

I checked. They said... NO.

Thanks for making me check into it!

I still like the design and still want to build it. I just need to reconsider size / power.

I sim'd with 2x Max F's... 120m. and I build heavy... so no way.

Build it as designed with a single 38 mm MMT. A G78 sims at 170m. That's borderline. And I don't like the idea of compromising design for local field when the max motor is only a maybe...

A can down scale to a 3" body tube.... would probably be 36" BT with a 15" nose cone. 51" LOA. Would use a single 29mm vs 38mm MMT. This is the only option for satisfactory local use. Need to sim it though.

The final option is to build it as designed. Forget local field flights.

Not sure what approach to take. I'm going to sim the 3" BT option.

No surprises when doing a rough sim at 3". Minimum power would be something such as F50.

Now just to decide what I want...

qquake2k said:

I'm glad you checked before you got there and were turned away. If it were me, I think I'd go 3", so I could launch it at my local field. You can always build a 4" later, if things change and you have a place for HP flights.

Click to expand...

I have HPR field in the vicinity,... just not as convenient. about 1.5-2 hours away. the local field is 30 minutes.

I'm leaning toward the 3" as well...

Quaranta said:

I have HPR field in the vicinity,... just not as convenient. about 1.5-2 hours away. the local field is 30 minutes.

I'm leaning toward the 3" as well...

Click to expand...

Well in that case, build both! I'm a member of two clubs, one field is about 30 minutes away, the other is 1-1/2 hours. There was a time when the local field only allowed up to G motors. But I always went to both launches. I probably enjoy MPR slightly more than HPR, that's why I suggested the 3". Sounds like you'd get to fly it more often. And with a 29mm motor mount, you can always throw it up on a baby H if you get the chance.

Ha. No only 1 version. The 3 " version is the most sensible. Need to investigate whether I want 29mm or 38mm MMT. My thought has always been you can adapter down... so start bigger.

Which field are you referring to that is 1.5-2 hours away? I think Tripoli South Florida is a lot closer to Ft. Lauderdale than that.

Tripoli Ft Myers. They launch in LaBelle, FL 33440.

Tripoli South Florida lost access to its former site a couple years back.

Oh. I guess the Rocketreviews club finder hasn't been updated recently.

I appreciate you looking. West palm is also only up to G.

Quaranta said:

Ha. No only 1 version. The 3 " version is the most sensible. Need to investigate whether I want 29mm or 38mm MMT. My thought has always been you can adapter down... so start bigger.

Click to expand...

I get told that on a lot of my builds, that you can't adapt up. But I look at the big picture. I never want a motor eject rocket to go over 2000 feet, so what's the use of being able to put an I600 in a 2lb rocket? Another thing I look at, is mail ordering motors. We don't always have an onsite vendor, so I've had to order motors a lot. Most 29mm reloads, even H, can be shipped without the hazmat fee. All 38mm reloads, including G, incur the fee.

This design is going to require 6-8 oz of nose weight with big engines,... so it'll be close to 1500 grams (3.3 pounds) on the pad with bigger engine. I agree with you on the 2K height limit for engine deploy. I usually target 1500 feet. That said, I already own 38mm aerotech / CTI HW.

I order engines online as like to know what I have before I go... I try to order 10-20 at a time. reduces the impact of the HazMat Fee.

I've decided to go 3" x 33" body tube (FG). single 38 mm x 15" MMT. 5:1 FG nose cone. Wing fin profane modified slightly. flies to 1800 feet on H123.

Parts ordered from Tim / Wildman...

My boys are 4 and 6,... Every thing's cool to them. But they already appreciate a good CATO.

Best wishes to you and yours.

Thanks again for the prompt to check 2xG.

All parts have been ordered.

I'm expecting it take a while for all the pieces to arrive,...

I'll resume / continue this thread as the build thread, when all the parts are assembled. Build likely to start in september.

Thanks for the input.