A supersonic Apogee Aspire...

[snrkl]

Ok, so I have an apogee aspire on my build pile and I am pondering an attempt to take this thing supersonic... For those that haven't seen it, it is a 29mm MD kit from Apogee



I am a strong believer that if I am going to fly faster and higher than I have to date, then there is no point doing it unless:
a) I have an altimeter that can tell me how high and fast I flew; and
b) I can actually get the rocket back again..

This means that if I am going to do this, the aspire needs to have a GPS tracker and an altimeter...

My research so far has me looking at an Eggfinder mini for the GPS part and I am planning on running my JLA3 for flight data..

Initial investigations showed me that the weight of the Eggfinder mini + LiPO and the JLA3 prevented me from getting to supersonic, but a little more research into motors available to me has shown me that an Aerotech G80T-14A 29MM DMS gets me to Mach speeds with the added weight...



View attachment Apogee_Aspire.rkt




As I think through the likely build, there are two key unknowns for me that I can see, that I am interested in peoples thoughts on:

1) AV gear in the nose cone - can I actually get the EFMini and LIPO into the nose cone.. I fear that this might just have to wait until I buy the kit, assemble it, and try it out...

2) My largest current concern is motor retention - what do people use in these scenarios for MD motor retention? Up until now, I have used tape wraps on the engine overhang for motor retention.. I have SERIOUS doubts on the viability of this for a supersonic flight...

I have thought about a glue and screw ring retainer pack, but the drag induced by even a 1mm raise in diameter at the tail has serious impacts to flight performance.

I also seem to recall seeing / hearing about metal rings that slip into the tail somehow to provide a lip for rearward retention..

I have also considered a wire on the outside of the airframe that passes across the base edge of the motor, but I have no idea what people anchor those to, and what the impacts to flight performance would be like..

What do people use for retention on MD motors that need the motor ejection (ie: not electronics driven) charges?

 

[dhbarr]

Tape'll be fine, it's only Mach 1. Chopping some of that BT length will cut weight & add speed.

 

[ksaves2]

A fire and forget rocket if I ever saw one. I lost one on a G80-10 and a major launch and it was somehow returned to me after the launch was over. Flew it on several smaller motors and got one more G80-10 and three F10-8's out of it.
Used a very long metallic silver steamer which helped on the mile high flights. Last F10-8 it disappeared for good. That's o.k. as it was getting pretty ratty by then and my experience was probably better than most. Put those big motors in there
and most lose them on the first or second flight.

That said, I do have another Aspire clone in the wings with an EggFinder mini in a nosecone/payload bay on the bench. Forget about a Mach flight if only using a G because of the added weight. Could do a baby H and probably hit Mach.

I'd like to see a mini Jolly Logic Chute release that could fit because that would make an H flight practicable as I think even a long streamer might be too much still for a confined area. Plus a streamer would mean the rocket is going to take a good hit when it lands.

An Aspire-like rocket with an EF mini along with a smaller JLCR and one would be able to get very economical GPS tracking practice with a pseudo dual deploy platform. Lose it and you don't have so much tied up in the loss.
(Ummmm, unless there is a JLCR "type" device in there!):wink:
Find your small tracked rocket and you'll have no trouble locating a large M ship.

A Wildman Jr. on J's can give completely sight unseen flights from launch to landing. If one can master that, they'll be set for anything. Kurt

 

[WoShuGui]

I have flown an Aspire on G motors a couple times using a few wraps of masking tape for motor retention with no problem. I was lucky to get them back though. It will disappear immediately. Definitely want to go streamer. Not likely to exceed Mach with any added weight though. This one was on a G78G and a Jolly Logic 2 altimeter. The JL2 reported 1046 mph, but clearly this rocket did not go that fast.
[video]https://m.youtube.com/watch?v=7NWCxRTdObM[/video]

 

[snrkl]

That said, I do have another Aspire clone in the wings with an EggFinder mini in a nosecone/payload bay on the bench. Forget about a Mach flight if only using a G because of the added weight. Could do a baby H and probably hit Mach.

The attached RKT sims to Mach 1.1 with an AT G80 and the eggfinder mini + LiPO + JL altimeter 3..

Whether that actually happens or not is part of the fun...

 

[ksaves2]

I doubt Mach with a tracker or electronics on board in spite of what the simulation says. It's always going to be heavier than you think. To hit high speed you have to go as light as possible. In that state
you trade altitude for top speed. If you want the max altitude there is a "throw weight" you have to hit in order to go as high as possible. Plan for max altitude and your speed suffers.

Take my advice, do a single use motor. It doesn't hurt as much as there is no hardware to lose. If you have a good tracker on board then the risk of loss goes down. As I said previously I was surprised to
get two G80 flights (SU motors no electronics) and they probably touched Mach. The long burn F10's of course no Mach but go really really high. Kurt

 

[K'Tesh]

I was working on a sim of the Aspire at one time, but looks like it was lost in the "HD Crash of '16".

Can someone scan the Instructions, as well as fins (with a ruler along the root edge), and the decals (again with a ruler). I don't trust .rkt files at all (I know that I didn't make the sim, and thus it is suspect in my book).

I would also appreciate it if someone could measure the thickness of the fins, as they seemed to me to be a tad thicker than 1/8", as did the Apogee Diamondback I have (in a shipping container in the US).

Thanks

 

[BDB]

John Beans has hinted that there is a new altimeter that is super small. It might be perfect for something like this. I'm hoping it will be available for Christmas.


Sent from my iPhone using Rocketry Forum

 

[dhbarr]

JL4 is tiny, but not a tracker AFAICT.
Several capable barometric detect-only altis are readily available.

 

[BDB]

JL4 is tiny, but not a tracker AFAICT.
Several capable barometric detect-only altis are readily available.

That's right. For tracking, I think the best options are teleGPS or Eggfinder Mini.


Sent from my iPhone using Rocketry Forum

 

[OverTheTop]

As people have said, keep the mass down. Streamer will help with that, due to less volume, and closer recovery too. Just make sure the fins are strong enough for the landing.

For streamer length I seem to recall reading that a length of 13x the width was about optimum. Any more than that was little return.

I would also fly it earlier in the day so there is a greater chance of somebody finding it when looking for their own rockets.

 

[rstaff3]

As people have said, keep the mass down. Streamer will help with that, due to less volume, and closer recovery too. Just make sure the fins are strong enough for the landing.

For streamer length I seem to recall reading that a length of 13x the width was about optimum. Any more than that was little return.

I would also fly it earlier in the day so there is a greater chance of somebody finding it when looking for their own rockets.

A longer streamer may not help from a recovery speed point of view but the longer it is, the easier it is to see. Our eyes can pick up long skinny things easier than stubby fat ones (within limits of course). I saw a discussion that explained why, but don't remember the details. I thought I agreed from my own experience before the floaters got too bad. I did read it on the internets so it had to be right...right?

 

[Buckeye]

I agree that the Aspire is a fire and forget rocket. Put in an F10/G80, believe the simulation that says it went mile/mach, claim success, and brag to your non-rocket friends about it. Done.

A sturdy fiberglass rocket (Go Devil, Blackhawk) may be a better platform to carry multiple electronics, ebays, and high kick motors while surviving a hot streamer descent.

Any speed measurement will be iffy with an altimeter, anyway. You still need a simulation to verify it.

Personally, Mach 1 doesn't do anything for me. You can't see it, you can't hear it (despite what the layman thinks about sonic booms), and it is hard to measure accurately. Altitude, on the other hand, is more tangible to me, and is reliably captured with barometric altimeters. Now, I could get jazzed about higher Mach numbers that melt paint off my nose cone......

 

[ksaves2]

I agree that the Aspire is a fire and forget rocket. Put in an F10/G80, believe the simulation that says it went mile/mach, claim success, and brag to your non-rocket friends about it. Done.

A sturdy fiberglass rocket (Go Devil, Blackhawk) may be a better platform to carry multiple electronics, ebays, and high kick motors while surviving a hot streamer descent.

Any speed measurement will be iffy with an altimeter, anyway. You still need a simulation to verify it.

Personally, Mach 1 doesn't do anything for me. You can't see it, you can't hear it (despite what the layman thinks about sonic booms), and it is hard to measure accurately. Altitude, on the other hand, is more tangible to me, and is reliably captured with barometric altimeters. Now, I could get jazzed about higher Mach numbers that melt paint off my nose cone......

Agree about Mach. It's no big deal as you can't hear the boom anyways. I will say that sometimes one can see a dip in the altitude curve as the shock wave goes over the airframe as the rocket goes sonic and also a smaller dip when it comes out of
supersonic flight. I've seen it in curves from an MAWD right at the time spot the sims said the rocket would be going in and out of Mach. You can some times pick it up in some devices data.

Glass rockets? Yeah, land in dirt and you can escape damage outside of paint (if you painted it) Shoot, I could'a completely saved a ballistic glass rocket if I had been able to free up the nosecone out of farmland clay without cracking it!
Nonetheless, new nosecone shroud and I was back in business (NC carried a tracker inside and I pem nut"ed" and button head screwed the shroud on to the coupler. The coupler was salvaged. I stuck a little flashlight inside the coupler
shroud assembly and viola' I could see where to drill the hole for the new shroud attachment!) Kurt

 

[snrkl]

Ok - so I've ordered a second kit to make the g80 and I'm using this kit as something to work up to the g80 in.

I'm waiting on eggfinder minis to arrive so I have a hope of getting these back - until then flights will be well simmed before flying to ensure I have a clue what it will do in wind.

Mandatory kit layout pic - not much to this kit really.



This was my first time airfoiling fins.

Process I used was to mark a line 1cm on the LE and TE, tape with blue masking and sand from there.



I found marking a center line on the edges being airfoiled made it much easier to see which side material needed to be removed from.

The first fin I did, I removed a little much and accidentally built a step in the fin running the sanding block parallel to the masking. (Oops)..

Fins 2,3 and 4 got progressively better as I found my groove with the process.

View from the root edge:


And tips (same fin order - 1to4 top down)


If my epoxy putty arrives in time I'll use that to fillet these fins, otherwise I'll fillet with 5min epoxy.

Fins are yet to be papered - I have one question first:

Should I CWF that first fin's airfoil and re-sand it or press on regardless?

 

[snrkl]

Referencing TVM's research, I'm bevelling the Leading edge of the launch lugs and leaving the trailing edge square:

https://www.apogeerockets.com/downloads/PDFs/launch-lug-drag.pdf

I'm not going to inverse cut the trailing edge, but it will be well filleted.

 

[dhbarr]

I'd run to the spare parts bin or a hobby shop to grab some more balsa, cut 3-4 more fins.

Sand 'em all and pick the ones that are most similar by profile & by weight.

 

[snrkl]

I'd run to the spare parts bin or a hobby shop to grab some more balsa, cut 3-4 more fins.

Sand 'em all and pick the ones that are most similar by profile & by weight.

I've got balsa and had the presence of mind to photocopy one fin before profiling.

Ok. I know it's the right answer but it's the "more work" answer.

It's funny - fin sanding and papering are the one part of builds I really don't care much for. I can sand a rocket for paint/finish all day and find it quite therapeutic but I find sanding fins a PITA...

 

[ksaves2]

I've got balsa and had the presence of mind to photocopy one fin before profiling.

Ok. I know it's the right answer but it's the "more work" answer.

It's funny - fin sanding and papering are the one part of builds I really don't care much for. I can sand a rocket for paint/finish all day and find it quite therapeutic but I find sanding fins a PITA...

I speak both coming from a scientific background. Oh nothing wrong with metric. In many ways makes more sense.

Other thing is I understand in Australia you might have easier access to some wide open spaces. Makes it easier to recover a project like this.

I do think you will have to get Mach out of mind because if you load this with electronics, it is not going to happen
without a baby H motor. Kurt

 

[snrkl]

I speak both coming from a scientific background. Oh nothing wrong with metric. In many ways makes more sense.

Other thing is I understand in Australia you might have easier access to some wide open spaces. Makes it easier to recover a project like this.

I do think you will have to get Mach out of mind because if you load this with electronics, it is not going to happen
without a baby H motor. Kurt

The Mach question is interesting - with weight added for the gps & LiPO and the AL3 I'm still getting Mach 1.05 on a ATg80 in OR and Rocksim.

I'll know more when I finish the second build (which will be made for the g80) and get final finished weights.

Whether it's likely to happen or not I'll still be trying it - time and hopefully data will tell...

 

[K'Tesh]

Bump...

I'd like to sim this for myself if someone would be kind enough to scan the fins in (along with a ruler) so I can finish it (once my computer's back up and running fully again). I also need the decal scanned.

Thanks

 

[ksaves2]

It'll turn out heavier than you think especially if you paint it. If you want it to go as fast as possible it needs to be as light as possible. Speaking from the point of view of doing a couple of G80 flights in an Aspire that was painted, push the button and it will do a disappearing act. Maybe it broke Mach. Kurt

 

[K'Tesh]

Thanks to snrkl for the scans I asked for... Once I get my computer problems sorted out, I'll get on that sim.

 

[snrkl]

I wasn't happy with the consistency of the fins I airfoiled.. I also realised that airfoiling back a full centimetre has made the fins much thinner then I wanted.

So I made a jig. Decided to only shape back 5mm back from the LE and TE.

A little math in a vector app and figured out the dimensions for the triangles needed to sand the correct angle.

Some foam core and a few old business cards later (wood glue and masking tape) and we have a jig:




I've also figured out how to put the 1/2 thickness line on the edge - mark it and run some tape, then colour one side with a sharpie:



Used two business cards under the sandpaper to accomodate for the card and tape thickness in the jig.





All up - I'm happy with the process and the results: (scrap test)

 

[snrkl]

Four fins complete with a very consistent double diamond airfoil:





"In Jig We Trust"...

Fins are now papered and drying. Soon to be CA Sealed and final sanding before being epoxied onto the bodice...

I need to get this first kit finished and painted this weekend as I intend to fly it on the 15th and work is flat out next week - I'll have zero rocket construction capability.

 

[snrkl]

So now I have two aspire kits, this one will be built mostly stock for E and F motors. I have two E20-7Ws DMS motors for next weekend, and depending on how recoverable it is on those, I might fly my new F35-7 RMS in it.


Rocket will be called Aspera-1 from the latin meaning "Rough", "Hardships" or "Difficulties"... This is in tribute to my favourite Latin quote: "Per Aspera, Ad Astra" -> "Through adversity, to the stars" or my preferred translation, "To the stars, the hard way!"

I'm hoping @cerving will soon mail me to advise my eggfinder mini kit is en route.

Once I have that built and tested I'll be constructing the second kit specifically for supersonic and/or high altitude RECOVERABLE flight, most likely on a G80-NBT-14...

The G80 is simming to 1234m at Mach 1.1 at present with more nose weight than the EFMini and JLA3 carries - there are some variables to play with once I build the NC-AV bay.

I've been experimenting in OR on modifying the kit (optimised fins, aft tube much shorter with more nose weight) to kiss the 1524m waiver at my local club.

This variant is currently simming on the G80-NBT to 1643m at Mach 1.25, so I might have to look at ways of reducing altitude by reducing NC weight. I'm also sure once I put the epoxy clay fillets on the fins, the weight OR is coming up with will need to be adjusted.

 

[snrkl]

Papering double diamond fins.

Some of the TE edges were separating after they dried.

Peeled them back carefully, used a fine paintbrush to re-apply a little wood glue and burnished them back down.



Once dry, I trimmed root and tips with a new #11 then thin CAd the whole fin. I'm using epoxy so it doesn't matter if I CA the root edge.

Once CAd I fine sanded the trailing edge - these things are almost knife sharp... loving it! 😜

 

[K'Tesh]

Looks good to me.

 

[snrkl]

Fins on and filleted. I considered using the epoxy clay, but I don't have time for the 24hr cure - in order to fly this next weekend, it needs to be painted tomorrow morning... I filleted with 5min epoxy...





Left to do:
- sand the NC
- install teabag shock cord and attach streamer
- glue engine block

The engine block is going in - this one will fly only on 24mm motors.

It's brother that I'll build Week after next will be built for G-motors and will have a different engine block location.

 

[snrkl]

Filler- primed, sanded with 400 - re-primed.

Will be sanded again with 400, wiped clean, then sprayed gloss white with rusto 2x..

I won't get time today to mask/orange it, so I'll have to do that next Saturday morning when I get back from my work trip.