Full Scale Arcas build

[maverickrocketry]

I have a current build going. Its a Full Scale Arcas 4.5 inch with the 98mm. At this point I dont have a chosen motor. Depending on altitude possibly a M1939 but I am an open book.

I am gonna use 3 1010 rail buttons.
Dual strataloggerCF's
Missileworks RTX GPS
Comspec/Marshall radio tracker
Sky Angle 24 inch drogue
Sky Angle 60 inch main
Kevlar shock cords
98mm Slim Line from Giant leap.

 

[maverickrocketry]

Just using JB WELD glue on CC.

For the 98mm slimline retainer to fit the 4.5 airframe I had to grind down the lip on it. No big deal.

 

[JackC]

I have a current build going. Its a Full Scale Arcas 4.5 inch with the 98mm. At this point I dont have a chosen motor. Depending on altitude possibly a M1939 but I am an open book.

I am gonna use 3 1010 rail buttons.
Dual strataloggerCF's
Missileworks RTX GPS
Comspec/Marshall radio tracker
Sky Angle 24 inch drogue
Sky Angle 60 inch main
Kevlar shock cords
98mm Slim Line from Giant leap.

You are probably going to need the Sky Angle Cert 3 Large chute for your main. The rocket will probably weigh 20 pounds or so dry weight and with the M1939 you can add a few more pounds for the motor casing. With the 4.5 inch airframe, you should not have a problem fitting the chute.

 

[maverickrocketry]

You are probably going to need the Sky Angle Cert 3 Large chute for your main. The rocket will probably weigh 20 pounds or so dry weight and with the M1939 you can add a few more pounds for the motor casing. With the 4.5 inch airframe, you should not have a problem fitting the chute.

You are probably correct. I have a cert 3 large. That wont set me back. Have to see. I am just hoping to get away with a 60 inch and not the bigger one but if I have to I will.

 

[maverickrocketry]

completed motor tube with CC'S and slim line installed. Its really slick how the slimline is nestled in the back end once installed into airframe.

 

[maverickrocketry]

I have 1/4 inch stainless U-bolts for recovery attachment. As you can see in the pictures would it be worth getting longer U-bolts so that there are more threads sticking out of the lock nuts?

 

[JackC]

I have 1/4 inch stainless U-bolts for recovery attachment. As you can see in the pictures would it be worth getting longer U-bolts so that there are more threads sticking out of the lock nuts?

Yeah, I think you should get longer U-bolts. Just the next size longer should do it.

 

[bobtheshortstop]

I’m glad the parachute size came into question. I’m just about done building my full scale Arcas. Mine is the 75mm Proline rocketry version. It’s gonna be about 16 pounds when finished. My plan is to use a 30” top flight for a drogue and a 60” wildman recon for a main. For now the largest motor I’ll be flying in it is an L900DM, which is about 10 pounds when loaded, after burnout it’s about 5 pounds. Making the rocket about 21 pounds while descending. I’d imagine a 60” main would be ok for it? Any advice would help. If I have to, I’ll pull the trigger and get a cert 3 size if I have to.

 

[JackC]

I’m glad the parachute size came into question. I’m just about done building my full scale Arcas. Mine is the 75mm Proline rocketry version. It’s gonna be about 16 pounds when finished. My plan is to use a 30” top flight for a drogue and a 60” wildman recon for a main. For now the largest motor I’ll be flying in it is an L900DM, which is about 10 pounds when loaded, after burnout it’s about 5 pounds. Making the rocket about 21 pounds while descending. I’d imagine a 60” main would be ok for it? Any advice would help. If I have to, I’ll pull the trigger and get a cert 3 size if I have to.

You can go with a smaller drogue; (24”) is more than enough.

The weight you cite seems light. Mine is 19 pounds empty. With an empty motor, it would be 24 pounds. Since it’s all fiberglass, using the Wildman chute would bring it down in the 25 fps range which is survivable for it but fast. Since you have the space in the airframe, I would go with the Cert. 3 large chute, FWIW.

 

[ChicagoDave]

At 24fps I broke a fillet on my ARCAS so I sized up the chute to bring it down at 18fps. If may have been just bad luck or undersized fillets, but I would still recommend coming down a bit slower under main just to be safe.

Also, personally I would go with 1515 buttons for M and larger motors - the clubs I fly with don't usually have 1010 rails at the M and larger pads, so it'd be an extra step to get a rail out there. YMMV but that's the usual convention around here so you may want to check with your club(s) to see which is the better choice.

 

[3stoogesrocketry]

I have 1/4 inch stainless U-bolts for recovery attachment. As you can see in the pictures would it be worth getting longer U-bolts so that there are more threads sticking out of the lock nuts?

Use the same Ubolts that you already have . Simply remove the lock washer directly under the locking nut , then remove the cross bar . You do not need the cross support on G10 , it will not crush like wood . Or keep the washers and simply buy standard nuts as the crush / lock washer is already there .

 

[JackC]

At 24fps I broke a fillet on my ARCAS so I sized up the chute to bring it down at 18fps. If may have been just bad luck or undersized fillets, but I would still recommend coming down a bit slower under main just to be safe.

Also, personally I would go with 1515 buttons for M and larger motors - the clubs I fly with don't usually have 1010 rails at the M and larger pads, so it'd be an extra step to get a rail out there. YMMV but that's the usual convention around here so you may want to check with your club(s) to see which is the better choice.

I agree with the 1515 rail guide idea. If you want to be super prepared, do 1010 on one side and 1515 on the other.

 

[H_Rocket]

Get close to scale on the burn - M750 (a little less than half the burn time but beggars can’t be choosers).

 

[maverickrocketry]

Great Advice!!! I think 1515 buttons is over kill. Using (2) drilled and tapped holes with 1010 buttons into the CR'S and (1) 1010 in the swtich band of the av bay is sufficient. For a total of 3 1010 rail guides should be good. That's my 2 cents.

 

[JackC]

Great Advice!!! I think 1515 buttons is over kill. Using (2) drilled and tapped holes with 1010 buttons into the CR'S and (1) 1010 in the swtich band of the av bay is sufficient. For a total of 3 1010 rail guides should be good. That's my 2 cents.

Yeah, I only use 1010 buttons on anything under 30 pounds and never had a problem in 15 years or so. Also, I just go with 2 buttons, not 3. Never had a problem with using just 2 as long as there is 36 inches or so between the 2 buttons during the same time period.

 

[JackC]

How is your build going?

 

[RocketTree]

I have 1/4 inch stainless U-bolts for recovery attachment. As you can see in the pictures would it be worth getting longer U-bolts so that there are more threads sticking out of the lock nuts?

I would place them in a vice and add more threads, with a standard tap and die kit. In the pictures, it looks like you still have room on the U bolts to do this.

 

[Ez2cDave]

I have 1/4 inch stainless U-bolts for recovery attachment. As you can see in the pictures would it be worth getting longer U-bolts so that there are more threads sticking out of the lock nuts?

Extra threads, protruding beyond the nuts, do not provide more strength.

Dave F.

 

[maverickrocketry]

How is your build going?

slow lol. but coming along. waiting for stuff in the mail

 

[jd2cylman]

Use the same Ubolts that you already have . Simply remove the lock washer directly under the locking nut , then remove the cross bar . You do not need the cross support on G10 , it will not crush like wood . Or keep the washers and simply buy standard nuts as the crush / lock washer is already there .

This. No need for lock washers and lock nuts. Removing the lock washer will allow the lock nut to do its job. If you think that’s not sufficient, add a dab of red Loctite.

 

[jFlds]

I have one from CW that is 20 lbs dry.

I went drogueless with a 9 ft Rocketman standard as a main. Nice smooth decent rate around 17 fps

I've got 1010's on mine since I don't really plan on doing anything over an L in it. Flies great on K850 DM is you want to keep it around 3K and save yourself a walk!

 

[Andrew Evans]

I'm following along with your build. I too someday want to build a full scale Arcas. My biggest issue is scaling those fins. Someone was making them from machine aluminum but no longer available as far as I know. It seems for scale that is the way to go. How are you building your scale fins?

 

[JackC]

I'm following along with your build. I too someday want to build a full scale Arcas. My biggest issue is scaling those fins. Someone was making them from machine aluminum but no longer available as far as I know. It seems for scale that is the way to go. How are you building your scale fins?

Mike Fisher of Max Q has made scale Arcas fins out of aluminum. Check with him.

 

[Andrew Evans]

Mike Fisher of Max Q has made scale Arcas fins out of aluminum. Check with him.

Thank you and good to know!

 

[maverickrocketry]

My avbay is coming along. All stainless hardware. The tubes the sled rides on is 5/16 brake line which works our great better then brass tube. Ejection canisters from rocket junkies.

 

[joe7]

I have 1/4 inch stainless U-bolts for recovery attachment. As you can see in the pictures would it be worth getting longer U-bolts so that there are more threads sticking out of the lock nuts?

take a washer or two out and slather some jbweld or proline over the nuts?

 

[JackC]

take a washer or two out and slather some jbweld or proline over the nuts?

Probably doesn’t need the JB Weld. Looks like he has lock nuts.

 

[maverickrocketry]

Probably doesn’t need the JB Weld. Looks like he has lock nuts.

yea i guess its its overkill. lock nuts and lock washers.

 

[joe7]

Probably doesn’t need the JB Weld. Looks like he has lock nuts.

sure, i meant as an alternative to getting new hardware - shorten the stack so there is still some excess threading, then use the glue since the desired washers were gone..

 

[JackC]

yea i guess its its overkill. lock nuts and lock washers.

How is the build coming along?