R/C conversion of the 2.6" Estes V2 into a semi scale manned A4b

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aerostadt

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I bought a 24 mm Rocketarium retaining system from Apogee and attached to the aft end of the stuffer tube with JB Weld. This should insure that the stuffer tube is ejected on the next flight without ejecting the 24 mm motor. I took a file and just light removed a few high points on the lead wrapping on the forward end of the stuffer tube. The stuffer tube should be ejected on the next flight.

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aerostadt

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I had bad luck with the German A4b at Hellfire-22 flying on an E12-4. The E12-4 worked fine (lot# A 06 22 12) and the Apogee motor retainer worked, also. I used the Orange transmitter, which had only a small amount of flap change using the trim control. The flap lever on my Orange transmitter does not work. I knew this before the flight. I am thinking now that I should have used the joystick to bring the nose up, but I didn't do anything. The A4b stuck in the salt with damage. I am thinking of making taking out the R/C and setting the flaps to the right amount after the pop pod has ejected. The pop pod was also damaged on impact.

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Charles_McG

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I've always though it interesting how much the A4b looks like the F-25 Firelily.
(I didn't try to RC mine, though!)

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TheTellurian

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Well it sounds like its repairable but unfortunate none the less. That Orange is a Lemon [no offense to Lemon owners] That is one huge area for recovery with no trees, good for boost gliders though. A bad hip means flying it back to myself is the only way for me.


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aerostadt

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After crashing my R/C German A4b (see Post#92) patterned after Tom's design that started this thread, I decided to take out the R/C components and convert the model to a more conventional boost glider. It took some re-constructive surgery just to get the model to the condition shown in the photo's. Anyways, I tied one end of some LPR shock cord elastic to the end of the push/pull rods and the other end to an internal post to install an up-elevator position. Then I cut up pieces of motor mount tubes to make grooves on the pop-pod tube to hold the elevators in a neutral position during boost.

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kuehnx

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These look awesome guys! I can't help but look at these though and wonder if anyone is planning on or has done an up-scaled RC A4b using any of the larger LOC Precision V2 kits...
 

aerostadt

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These look awesome guys! I can't help but look at these though and wonder if anyone is planning on or has done an up-scaled RC A4b using any of the larger LOC Precision V2 kits...
I tend to think that the LOC V-2 kit would be too heavy. One thing that I have picked up from Frank at DynaSoar Rocketry is that rocket gliders and boost gliders need to be as light as possible.
 

burkefj

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You could do a non gliding version using a loc kit, too heavy to glide. I have done a gliding rc version in profile of 6" diameter that weighed 12 oz, there has been one ultra lightweight depron 6" full fuse version that flew as an aircraft but could do vertol, the construction was artwork, used a pusher or fan I think.
 

burkefj

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[video=youtube_share;OMXVyAwNMTc]https://youtu.be/OMXVyAwNMTc[/video]

Mine also flew as a rocket glider by popping the electric motor off.

[video=youtube_share;gyJWWXoDn8I]https://youtu.be/gyJWWXoDn8I[/video]

[video=youtube;KL9M-1fJjzA]https://www.youtube.com/watch?v=KL9M-1fJjzA[/video]
 
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aerostadt

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My A4b cockpit was damaged in last summer's crash. I got a new cockpit from The Sandman.

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aerostadt

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Tried this again on Saturday. Because there is a coupler in the repaired pop pod, an E12-4 would not fit. So, I flew it on an AT E15-4. Initially, the A4b flew straight up, but then it arced way over and headed towards the ground. About 50 feet above the ground the pop pod finally came out and there was a short glide. The pop pod body tube was bent, because it is so heavy with lead. The A4b is undamaged. However, even before flight there was some cracked fins. I need to inspect the model closely. I'm not sure why the model arced over so badly. It might be because of the fins. Also, after all the repairs the motor has moved aft a little bit in the pop pod, which is the wrong direction.
 

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SteveNeill

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Great stuff guys. Inspiring. I was Hostile Projectiles. Glad to see this stuff flying and pictures of my old kit. And it's nice to know where the CG is on that now. I plan to launch it soon.
 

aerostadt

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I tried the A4b again this past Saturday. This time I used a re-loadable 24 mm AT motor with an E18-4 reload. I drilled off about 0.06" on the delay charge, which I thought would be subtracting about 2 seconds. Since the volume that the pop-pod fits into is very small, I took out approximately half of the ejection charge. The A4b got good altitude on the E18 motor, but the delay for ejection was still a little bit too long. However, things would have been worse if I had not subtracted any delay. The ejection of the pop-pod worked fine. The A4b just fluttered to the ground or as one spectator said it stalled repeatedly. The flaps were deflected about 1/4" inch and I had not done any hand toss testing of the empty A4b. The pop-pod with its very heavy head-end was heavily damaged as usual. The tightly rolled parachute failed to open.
 

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aerostadt

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I have changed my mind again and have decided to go back to R/C. The last time I had R/C I was using the Orange transmitter. I am now using the Spektrum transmitter with the Spektrum AR 400 receiver. I have found a very light battery that works. The hard part was finding the corresponding electrical connector for the light battery. The weight of different 3.7v 1S Lipo batteries is interesting. The Dromida 700 mAh is 20 grams. The E-Flite 500 mAh is 13.05 grams and the E-Flite 150 mAh is 4.47 grams.
 

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aerostadt

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I want to thank Tom for posting this thread and introducing me to this model.

I launched this model successfully this past Saturday (03/37/2021) at the first UROC launch of the year. I went with the small E-Flite 150 mAh one-cell Lipo battery and the Spektrum transmitter. The Spektrum D-switch for up-flaps after boost really helps me. Although the German A4b has plenty of forward wing surface area, the boost is fast and straight up with an E18-4. Rocksim predicted over 800 feet altitude and my eyeballs would tend to confirm this. My wife was able to get some still photo's. The pop-pod was cleanly blown out. As I recall, I reduced the ejection charge on this reloadable motor. I don't know if the parachute opened on the pop-pod, but it looks like the body tube was only slightly bent, if at all. I was able to control the glider. There was some small damage to the glider where the snap-rivets hold the nose cone, but it is easily repairable.
 

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tab28682

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Glad to see you stuck with it and worked through the issues and had some success! I am back after a rocketry hiatus and hope to fly mine again soon.

I did do some work on a larger RC version of the A4b. One of my flying buddies gave me an Estes Maxi Brute V-2 kit. Some research showed that different releases of the kit has some pretty significant weight differences in the blow molded nose cone and tail cone, with the earlier releases appearing to have the lightest parts.

I think you could do a successful BT-101 size A4b using the early lighter parts, with dump-able water ballast nose weight to get rid of the boost pod. This could do well on various 24mm reloads.

The ultimate version might be to splash the nose cone, tail cone and the vac formed fins of the Maxi Brute V-2 and do very lightweight glass parts for the BT-101 tubing. This has the potential to fly at a nice light weight. Downside is amount of work involved and a rather fragile nose cone.

Might be able to have a thin wall ABS 3D printed nose cone and tail cone created that would be lighter than the lightest Maxi Brute kit parts, if a little heavier than the lightweight composite parts.

So many project ideas, so little time, even in retirement!
 

burkefj

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The other option is a profile model, mine works great, no balast dump, flies on E-6's, 6" effective diameter.....nice glide time.

Frank


Glad to see you stuck with it and worked through the issues and had some success! I am back after a rocketry hiatus and hope to fly mine again soon.

I did do some work on a larger RC version of the A4b. One of my flying buddies gave me an Estes Maxi Brute V-2 kit. Some research showed that different releases of the kit has some pretty significant weight differences in the blow molded nose cone and tail cone, with the earlier releases appearing to have the lightest parts.

I think you could do a successful BT-101 size A4b using the early lighter parts, with dump-able water ballast nose weight to get rid of the boost pod. This could do well on various 24mm reloads.

The ultimate version might be to splash the nose cone, tail cone and the vac formed fins of the Maxi Brute V-2 and do very lightweight glass parts for the BT-101 tubing. This has the potential to fly at a nice light weight. Downside is amount of work involved and a rather fragile nose cone.

Might be able to have a thin wall ABS 3D printed nose cone and tail cone created that would be lighter than the lightest Maxi Brute kit parts, if a little heavier than the lightweight composite parts.

So many project ideas, so little time, even in retirement!
 

tab28682

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The other option is a profile model, mine works great, no balast dump, flies on E-6's, 6" effective diameter.....nice glide time.

Frank
Agreed, profile is always an option. But, sometimes, you want a model that is not a profile.
 

aerostadt

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I have the Estes 4" diameter V-2 and have used it to make a 2-stage Bumper Wac (James Duffy has worked miracles with this Estes model) and I have noted it is very heavy. I, also, thought about making the Estes 4" diameter V-2 into a German A4b and realized it is too heavy. One of the reasons I stayed with this 2.6" diameter A4b for so long is that it looks too good to throw away. I, too, have other projects and I think I am going to move on. I can go back now and clean up some of the battle scars on my current A4b.
 

burkefj

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That was one of the advantages of the profile, light weight and large size with very good glide, sometimes in the larger models the number of hoops you have to jump through to get a light enough model to glide even with a pop pod is far beyond the reward, especially true for tail cone models, a build up depron version would be ideal, it has been done as a pusher electric RC plane the same scale as the profile one I did, but not as a rocket yet. Would require formers, stringers, skin etc, I'd do it if my profile version didnt' fly so darn well. You are right, sometimes the smaller models hit the right sweet spot for weight, cost and effort.
Glad this worked for you.

Frank


I have the Estes 4" diameter V-2 and have used it to make a 2-stage Bumper Wac (James Duffy has worked miracles with this Estes model) and I have noted it is very heavy. I, also, thought about making the Estes 4" diameter V-2 into a German A4b and realized it is too heavy. One of the reasons I stayed with this 2.6" diameter A4b for so long is that it looks too good to throw away. I, too, have other projects and I think I am going to move on. I can go back now and clean up some of the battle scars on my current A4b.
 

tab28682

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I have the Estes 4" diameter V-2 and have used it to make a 2-stage Bumper Wac (James Duffy has worked miracles with this Estes model) and I have noted it is very heavy. I, also, thought about making the Estes 4" diameter V-2 into a German A4b and realized it is too heavy. One of the reasons I stayed with this 2.6" diameter A4b for so long is that it looks too good to throw away. I, too, have other projects and I think I am going to move on. I can go back now and clean up some of the battle scars on my current A4b.
Yep, as I mentioned, the latter releases of the Maxi Brute V-2 had very heavy molded parts.

An alternative to the hassle of making a mold of the heavy V-2 parts would be to 3D print a thin wall nose cone and tail cone for the BT-101 airframe. This, with a water ballast release, is likely the best solution. Once you had those two parts in hand, the 4" diameter A-4B would be easy to build.

I got tired of waiting for friends to print 3D parts for me, so I finally broke down and ordered my own 3D printer. Might have to do the 4" V-2/A4b parts.
 

burkefj

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Tom, let us know what you are able to print in this size and the weight. The lightest I've been able to get in a 4" diameter by 10" length lightweight 3d printed or roll cast cone is 3.75 oz each. You'll have two of those plus the bt-101 tube, internal structure, radio and bladder mechanism etc, maybe around 12-15 oz glide weight, Still feasable as that's around my 4" X-15 glide weight but you'll have a bit less surface area for lift....

Frank

Yep, as I mentioned, the latter releases of the Maxi Brute V-2 had very heavy molded parts.

An alternative to the hassle of making a mold of the heavy V-2 parts would be to 3D print a thin wall nose cone and tail cone for the BT-101 airframe. This, with a water ballast release, is likely the best solution. Once you had those two parts in hand, the 4" diameter A-4B would be easy to build.

I got tired of waiting for friends to print 3D parts for me, so I finally broke down and ordered my own 3D printer. Might have to do the 4" V-2/A4b parts.
 
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tab28682

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Tom, let us know what you are able to print in this size and the weight. The lightest I've been able to get in a 4" diameter by 10" length lightweight 3d printed or roll cast cone is 3.75 oz each. You'll have two of those plus the bt-101 tube, internal structure, radio and bladder mechanism etc, maybe around 12-15 oz glide weight, Still feasable as that's around my 4" X-15 glide weight but you'll have a bit less surface area for lift....

Frank
I bet those print weights can be reduced a bit. Even at that weight, sounds doable and fun to me.

Or, go even bigger. Use Loc 5.5" tubing with the interior peeled out a good bit to get the weight down a lot and print parts to that size.

Likely to take some time to tweak the printer to do well with ABS and create an enclosure for it. Thin PLA parts are too brittle and too heat sensitive for me.

I don't mind a slightly heavy fast gliding rocket glider with a little less boost altitude and a little less duration as long as it looks really good. .....:)

Another project I am mulling over is a balsa and Monokote sport RC RG that is optimized for a G25 through G64, likely a swept delta wing type with the motor mount not too far from the CG to keep nose weight at a minimum.
 
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tab28682

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Well, I have been printing a number of things on my new printer while messing around and getting to know it. Currently, the printer is finishing up a section is a 4” V-2 nose cone that I scaled up (and thinned the wall of the print to .8mm) from a file on Thingiverse.

Not quite ready to commit to a 4” A4B, but I could sure see one happening. This print is PLA and a useable print would need to be ABS to survive the Texas heat. Would also need to do cad for a one piece nose cone. The V-2 file I found has fins incoroporated in the tail cone and would rather have a clean slotted tail cone and some sort of built up fins.

Will weigh it after the nose cone tip finishes printing.

By the way, am very happy so far with my Ender 3 Max. It is doing some really clean prints.
 

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tab28682

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Well. I now have a 108 g tail cone and a 92 g nose cone the size of the Maxi Brute parts. Certainly doable at that weight. However, am currently researching the new light weight PLAthat foams a little as it extrudes. Parts can be printed at somewhat less than half the weight of normal PLA.

The LW PLA would likely work for a 12-13oz A4b model for 24mm motors. The normal PLA parts might be just right for a test model at heavier weight, using 29mm motors. I have three G25s that need to be used. Releasable water ballast for CG control.

Have also been thinking about ways to manage an RC RG model at higher altitudes, perhaps 1200-1500 feet.

Planning on an upcoming test flight of a normal RC model that has a Spektrum SAFE type RX installed with custom values for SAFE, set to about a max allowable 15 degree bank and 5-10 degree pitch. The thought would be to have the ability to turn on SAFE if needed to limit pitch and bank if the model is hard to see at altitude after apogee. You could input a turn that would be limited by the SAFE RX and let the model spiral down a little. Once clearly in sight, turn off SAFE

The TX would be set up with a switch that activates SAFE on and off as needed. It would HAVE to be off for boost!
 

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burkefj

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The G-25 is a pretty heavy motor. Interesting take on using the safe modes. I've had good success at 1200' boosts on my 60" long orbital Transport glider, avro arrow and Aurora Clipper with 36" wingspans seeing them well enough, on a smaller model this may be very useful. I still find the fun is in the piloting so haven't used any stabilization or modes yet, maybe as I get older or my sight starts to fade I may break down and try this.

Well. I now have a 108 g tail cone and a 92 g nose cone the size of the Maxi Brute parts. Certainly doable at that weight. However, am currently researching the new light weight PLAthat foams a little as it extrudes. Parts can be printed at somewhat less than half the weight of normal PLA.

The LW PLA would likely work for a 12-13oz A4b model for 24mm motors. The normal PLA parts might be just right for a test model at heavier weight, using 29mm motors. I have three G25s that need to be used. Releasable water ballast for CG control.

Have also been thinking about ways to manage an RC RG model at higher altitudes, perhaps 1200-1500 feet.

Planning on an upcoming test flight of a normal RC model that has a Spektrum SAFE type RX installed with custom values for SAFE, set to about a max allowable 15 degree bank and 5-10 degree pitch. The thought would be to have the ability to turn on SAFE if needed to limit pitch and bank if the model is hard to see at altitude after apogee. You could input a turn that would be limited by the SAFE RX and let the model spiral down a little. Once clearly in sight, turn off SAFE

The TX would be set up with a switch that activates SAFE on and off as needed. It would HAVE to be off for boost!
 

tab28682

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The G-25 is a pretty heavy motor. Interesting take on using the safe modes. I've had good success at 1200' boosts on my 60" long orbital Transport glider, avro arrow and Aurora Clipper with 36" wingspans seeing them well enough, on a smaller model this may be very useful. I still find the fun is in the piloting so haven't used any stabilization or modes yet, maybe as I get older or my sight starts to fade I may break down and try this.
I like the idea of somewhat larger and heavier motors The water ballast would help keep the final glide weight under control.

I would rather be flying it myself than using SAFE mode, but it might be a useful
backup tool at times if the model is at the limit of vision.

The 4” A4b would be indeed harder to see at 1200 -1500 feet than your larger models. I still regularly fly an RC sailplane with altimeter and vario telemetry and I can still comfortably see its 6 foot span at 1200-1300 feet.

Will advise how the SAFE pans out for a model like this.
 

aerostadt

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Well. I now have a 108 g tail cone and a 92 g nose cone the size of the Maxi Brute parts. Certainly doable at that weight. However, am currently researching the new light weight PLAthat foams a little as it extrudes. Parts can be printed at somewhat less than half the weight of normal PLA.

The LW PLA would likely work for a 12-13oz A4b model for 24mm motors. The normal PLA parts might be just right for a test model at heavier weight, using 29mm motors.
These weights look interesting.
 
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