PML Spitfire MOD Suggestions

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Pyropetepete

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Bought one. Wanting to mod it... looking for ideas

Specs of the kit

Dia: 3.0"
Height: 50.7"
Weight: 41 oz.
MMT: 38mm
Airframe: Quantum Tube

PML Spitfire MOD Suggestions.....

Mine are

Dual Deployment (2 or 3 tube split)
Kevlar shock cord all round (OneBadHawk)
Ditch the piston
Aeropack 38mm retianer
Aeropack 38 - 29mm adapater

The dual deploy..

2 tube

dual_deploy_two_tube.jpg


3 tube

dual_deploy_three_tube.jpg


I've a Pro 38 3G case and spacers. Dead handy as the motor mount is 9'' long, same as the case. This also allows flights from an G46 to an I55 (7.2 burn time). Flight cost is £20 - £50 which I can live with. So the fin can needs to be a min length of 11.5'' as a PML coupler is 5'' long.

What's your ideas
 
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I used a 3 tube split (zipperless fin can) for my L2 rocket. I like the rocket and fly it a lot, but I will not use the zipperless design again on a DD rocket. I find it to be more trouble then it's worth. There is really no advantage to a zipperless design if you are using an altimeter to pop the drogue right at apogee every time, at least IMHO.

If you don't use the DD, I would keep the piston. Just make sure you don't use the full ejection charge on H and I motors. You shouldn't need more then 0.5g to 0.75g if you're using the piston with motor eject. Just keep the tube clean and always test the piston to make sure it's moving freely before flight.

Have fun.
 
blackjack2564 said:
2 tube. Fewer joints, less wobble.
Click to expand...

bill2654 said:
+1 on this and ditch the piston. Less to go wrong.
Click to expand...

Sound good to me, less messing about as well then. Thanks guys.

Been thinking about the piston. Every launch I've seen and video the prep behind the piston setup is too much. I'll stick with OneBadHawk recovery harness and nomex. Lighter as well.

So planning this layout.

Make an eBay from a coupler, studding, ubolt etc etc.

What length on the tubing. Even lengths all round?
 
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Pistons work fine contrary to what many will tell you... Just make sure it's sanded well. All the PML birds I've built (including a "stock" Spitfire) have used the piston and I've never once had an issue.
YMMV.
 
+1 to AlnessW on the piston.

As long as they move smoothly and easily when you push them down the BT during prep, they will work great. No need for dog barf, burritos, or any other type of chute protection. Just insert the chute and cord and go. My PML Callisto piston has been working perfectly for 11 years.
 
Handeman said:
+1 to AlnessW on the piston.

As long as they move smoothly and easily when you push them down the BT during prep, they will work great. No need for dog barf, burritos, or any other type of chute protection. Just insert the chute and cord and go. My PML Callisto piston has been working perfectly for 11 years.
Click to expand...
Exactly. My L1 bird (Small Endeavour) which is still flyable has a piston, and it always works just fine. The key is making sure they move smoothly down the airframe.

But it's your rocket so it's up to you...
 
So the 2 tube deployment option... where to cut?

The BT is 36'' long. Motor mount is 9''. Do I just cut the tube in half and be done with it making 2 sections 18''
 
My payload tubes are cut so they will comfortably hold all my recovery gear...and no more. Keeps the ejection charge size down.

So you will need: 1/2 the coupler space. [if av-bay/coupler is 6in then 3 ] plus NC shoulder [3-4 in?]

6-7 inch will be used by 1/2 coupler and NC shoulder + what ever space the shock cord/nomex/chute take up.

I stick the NC on.....stuff all recovery gear in tube as it will be packed for flight. Slide the coupler [with BP's on] into tube right down on top of recovery gear. Measure to see how much space is used...ad an inch or two for convenience . Then figure where to make my cut.

I always want any extra length on my fin can in case of accidents. I have many rockets ,where over time the fin can gets trimmed an inch or two, due to small zipper....bad deploy or rough ground hit. Never needed to trim a payload, seems like all my damage is to fin cans.

Depending on your set up... you may actually cut a bit longer payload than fin can to make DD easy. You are starting with a single rather short tube, due to modifying a single deploy kit. This is why I would fit everything before making a cut.........measure twice...........cut once!

My 2 cents anyway.
 
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blackjack2564 said:
My payload tubes are cut so they will comfortably hold all my recovery gear...and no more. Keeps the ejection charge size down.

So you will need: 1/2 the coupler space. [if av-bay/coupler is 6in then 3 ] plus NC shoulder [3-4 in?]

6-7 inch will be used by 1/2 coupler and NC shoulder + what ever space the shock cord/nomex/chute take up.

I stick the NC on.....stuff all recovery gear in tube as it will be packed for flight. Slide the coupler [with BP's on] into tube right down on top of recovery gear. Measure to see how much space is used...ad an inch or two for convenience . Then figure where to make my cut.

I always want any extra length on my fin can in case of accidents. I have many rockets ,where over time the fin can gets trimmed an inch or two, due to small zipper....bad deploy or rough ground hit. Never needed to trim a payload, seems like all my damage is to fin cans.

Depending on your set up... you may actually cut a bit longer payload than fin can to make DD easy. You are starting with a single rather short tube, due to modifying a single deploy kit. This is why I would fit everything before making a cut.........measure twice...........cut once!

My 2 cents anyway.
Click to expand...

I'll get the tape measure out I think. Thank you for such a informative suggestion on how to go about this. Lot of factors i'd not thought about!
 
Just wanting to check, the chute that comes with this is a 36''. Still okay to use this as the main for deployment around 800ft? Would use a small drouge
 
A lot depends on where you fly, the ground you recover on, and how much weight you add with your av-bay. If you have a relatively soft field and don't add a lot of av-bay weight, the 36" chute should be fine. It is a small cost upgrade to go with the 48" chute. This might be better since you are going DD.

You also might want to look at using 400' as your main deploy altitude. I've been going with 300' when the altimeter allows it.
 
Sorry for the delays on this. Am now picking it back up.

Need too measure things out. Also need to get my Asropack ASAP as this will hold me back more than anything.

In 2 minds about foaming the can. Tack the fins then foam the can??
 
skip the foam. All it will do is screw up your cg. Well glued fins are waay strong enough

Just one question, what speed are you going vs what's the speed of quantum tube?
 
Pyropetepete said:
Piston is out. It's swollen larger than the tube it's self! Balls to that!
Click to expand...

Turn the piston upside down. I don't understand why PML insist on putting it the wrong way round for the pressure to push the piston against the walls of the tube.
 
cbrarick said:
skip the foam. All it will do is screw up your cg. Well glued fins are waay strong enough

Just one question, what speed are you going vs what's the speed of quantum tube?
Click to expand...

I don't like to strain when on the toilet and quantum is fit for that purpose. I'll only fly this on a P38 3G so I's max. Will leave the foam thanks.

amell said:
Turn the piston upside down. I don't understand why PML insist on putting it the wrong way round for the pressure to push the piston against the walls of the tube.
Click to expand...

I'm not keeping it, it's been out the air frame for a week and has swollen larger than the frame. Too much messing about so in the bin
 
Been playing

  • PML CT-3.0 Phenolic Coupler Tube Length 5''
  • PNC-3.0Plastic Nosecone Shoulder Length 2.5''
  • Motor mount 9'' length
  • Overall body tube 36''
  • 1'' band cut needed for switch vent band

2 Tube type deployment

Body tube split in half 36 / 2 = 18
1 Body tube (upper) 1'' switch vent band cut off
3 tubes, 1x 1', 1x 17'', 1x 1''

Lower Airframe/Fin Can 18 - 9 - 2 = 7
7'' section for shock chord, drouge and chute protector

Upper Airframe/Payload Bay 17 - 2 -2.5 = 12.5
12.5'' section for shock chord, main and chute protector

Coupler being 5'' long, 1'' of this sit inside the AV switch vent band. This leaves 2'' per side for the BT's too attach to. 1 will be shear pins the other plastic rivets.

Not opened the 36" supplied chute but it's currently 6.5'' long. I'm sure this can be made smaller when wrapped/rolled properly.

I could make both section for the chutes the same, 9.75''. To do this I need to make the booster/fin can 2.75'' longer and the upper/payload 2.75'' shorter

IE...

Lower Airframe/Fin Can 20.75
Upper Airframe/Payload Bay 14.25

The above makes 35, then plus the 1'' for the av vent switch band 36'' done.

Not sure which too do
 
Last edited:
Looked again at this.

36" Body tube
Cut 1" for AV Switch Band
Makes 35"
Minus 9" for motor mount
Makes 26"
Split this in half
Makes 13"

If using a 7" coupler, 1" is used in on the switch band, leaving 6" which is then 3" either side this making 10" sections for chute, protector and shock cords
 
Having spoken on here about an AV bay in a different topic have come up with this.

36" Body tube
Minus 9" for motor mount
Makes 27"
Split this in half
Makes 13.5"

If using a 5" coupler and putting 2" in the main airframe top section and then 3" left for the fin can side this making 11.5" section for chute, protector and shock cords on the main air frame and 10.5" on the fin can lower airframe.

So 1 tube cut only, less messing about.

Now to size up a drouge
 
Where did you get the spitfire from in the UK? Tempted to get one myself. Drag race? :)
 
amell said:
Where did you get the spitfire from in the UK? Tempted to get one myself. Drag race? :)
Click to expand...

Paul at Model Rockets. Think I had his last. Patrick at GB Rockets has some. Contact him off his site as his shopping cart is disabled currently. He will send you a PayPal invoice for it. Drag race sounds good. Just trying to get my tube lengths correct for DD and my other item
 
1500991_10152466000601404_4553055716880703863_o.jpg

54mm sled and Mobius HD Shroud has arrived. Sadly the items for the AV build have gone missing in the post so a new set has just been sent.

Gives me time to workout the way I want too wire this and get the nuts, washers etc for the AV bay
 
 
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PML Parts arrived!!!! Quick layout



I marked which surface I wanted to glue



Asked in the how to section and was advised to mix a little water and yellow glue and give a 1st coat and let it soak...so I did





I gave this a proper thick sloppy coat and worked it in a little



Left them for 3 mins, then wiped all he excess off



Neat coat of Titebond II



M6 eye bolt and washer to clamp them up, already compressing a bit



9 mini clamps per set, this pushed loads more out, I then cleaned the edge and reclaped. I'll leave them over night



It's gone uber cold here and now the coupler will not fit the qantum tube, I'll need to sand it.

Once dry I can mark the holes for the 2 length of m5 studs for the AV Sled and get them drilled and one end can be made up at least.

Thinking for the fixed studding end

M5 nut
M5 spring washer
M5 washer
Bulkheads
M5 washer
M5 spring washer
M5 nut
 

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