PML MR-1

[JAL3]

The MR-1 is something that looks like it comes out of an ordnance inventory. Opening the bag, that impression is confirmed as one lookes at the parts. The Quantum tubing and glass fins make this a heavy and substantial rocket. The NC makes it even more so.

I am hoping to get a chance to do some HPR flying in May at the West Texas Thunder event so I started looking through some of the bigger kits sitting around and this one came up first. Mine came with a 29mm mount but it is availible with a 38mm mount as well.

 

[JAL3]

My first step on reading through the instructions was to take a closer look at the Quantum tubing. I had never worked with this stuff before. It came with a high gloss and an insert dealing with this material said that all surfaces to be epoxied or painted should be scuffed with sandpaper to promote greater adhesion. That being the case, I gave it a good scrubbing which removed the high gloss.

 

[JAL3]

THe kit came with 2 plywood centering rings. One of them has a slot to accomodate the nylon harness. I test fitted them in the BT and the motor tube and found both to be extremely tight on both the inner and outer circumferences. I started to sand them down. According to the instructions, a bit of tighness is desirable in the forward ring, the one with the slot, but the rear one should be loose enough to slip off without too much trouble. Eventually, these criteria were met.

A mark was made of the forward end of the motor tube and a band of epoxy was run around the circumference with a 1" gap for the strap hole. The ring was then seated. When the first bit of epoxy had set, the forward ring was filleted, again leaving a gap for the strap.

 

[JAL3]

The rear ring was then slipped on but not epoxied. To facilitate removal later, the instructions directed that I attarch 3 strips of cellophane tape to ring. This was done.

 

[JAL3]

The kit uses a piece of flat nylon strap for the recovery harness. It is supposed to slip through the notch of the forward ring. Mine would not and my attempts to get it to do so resulted in a frayed mess. I used a razor knife to cut off the fraying and form an angle at the end of the strap. I also used it to whittle away a bit more material and make the slot bigger. After doing that, I was able to use a pair of pliers to pull the strap through so that 4" were along the motor tube. A bed of epoxy was laid down and then the strap was embedded in the epoxy and held down with masking tape.

 

[JAL3]

The next step was to install the motor mount into the airframe. The instructions called for placing a ring of epoxy 7 inches in from the aft end. My swabs were only 6 inches long so I used some CA to glue a swab to a mixing stick. The engthened swab was then marked at 7" and a ring of epoxy was applied. The motor mount was shoved in, making sure that the strap was offset from all fin slots. It was pushed in until the end of the motor tube was flush with the airframe.

 

[JAL3]

Fin attachment began by applying a bead of epoxy along the root edge of the fin and then inserting the fin into a slot until it comes to rest on the motor mount. Once in place, alignment was checked and the fin was taped to hold it in position until the expoxy set. Then the next fin was done in the same manner.

 

[H_Rocket]

I've built 2 - here is a hint.

Lay a small piece of fiberglass over the launch lug on that standoff. it is very fragile - Or scrap the brass and use a peeled piece if cardboard tube. Then drill some holes (1/16" two 0r three) and let the epoxy flow through.

 

[JAL3]

I've built 2 - here is a hint.

Lay a small piece of fiberglass over the launch lug on that standoff. it is very fragile - Or scrap the brass and use a peeled piece if cardboard tube. Then drill some holes (1/16" two 0r three) and let the epoxy flow through.

I appreciate the tip.

I was planning on asking a question related to this but forgot.

I'd like to use a linear rail button, or failing that, standard rail buttons but have not come up with a way to make it work. If I can't, I'll certainly keep fiberglass in mind. THat will be my first fiberglass work.

 

[H_Rocket]

On one I ended up using a small PML linear rail guide after the lug repeatedly broke off.. I just ground the top edge of the web flat and used glass filled epoxy to fillet it into place. Looked a bit ugly, though it worked.

Actually this rocket would be way better if you ground the whole support off and used a tower launcher.

 

[JAL3]

On one I ended up using a small PML linear rail guide after the lug repeatedly broke off.. I just ground the top edge of the web flat and used glass filled epoxy to fillet it into place. Looked a bit ugly, though it worked.

Actually this rocket would be way better if you ground the whole support off and used a tower launcher.

Thanks again.

As I said, I have no experience with fiberglass. Do you have any pics of what you're describing? I'd like to avoid paying for a tower launcher in the near future.

 

[H_Rocket]

In the next day or so I'll go snap a photo of the FG one. The rail guide one ended up in a swamp.

 

[JAL3]

In the next day or so I'll go snap a photo of the FG one. The rail guide one ended up in a swamp.

I do appreciate it.

 

[n5wd]

... Opening the bag, that impression is confirmed as one lookes at the parts. The Quantum tubing and glass fins make this a heavy and substantial rocket. The NC makes it even more so.

Yes, but it's no match for an airport taxiway!

I flew my MR-1 with Houston's Tripoli-002 in December down at their Hearne (TX) airport launch site. I had read enough build threads and reviews to know that I wanted to ditch the brass launch lug, so I substituted a 1/4 paper lug. Launch day was a bit windy, and the first time the MR-1 was on the pad, a little gust of wind levered the rocket at the lug, and it promptly popped off. Ah, well.. a bit of sandpaper and a new lug epoxied on with 5-min epoxy, and we were set to go.

Maiden flight with a Roadrunner G-80 went well. It landed fairly close to the pad.. about 75 yards away after a nice flight to about 700 feet.

Next flight up on a Cessaroni H-153 and everyone lost sight of it as it took off like the proverbial scalded bandit. A couple of folks said they heard the ejection event, but no one.. and that was about 8-9 people all looking.. no one saw it deploy or land. No one heard a "screeeeeee-thunk", so hopefully it came in under chute.

One of the folks who left after my wife and I had already started back to Fort Worth, saw some pieces of white plastic on the taxiway as they were headed out, and then saw the rocket in the grass by the taxiway - minus the white plastic transition (the debris on the taxiway).

This was my first experience with the PVC ... errr.. Quantum tubing. I'm not impressed with its ability to absorb an impact on a hard surface, so if that's even remotely possible where you fly yours, think twice.

This is a small rocket, and it needs a tracker in it if you're going to fly it on anything larger than a G, because it can scoot out of sight in a flash. If it had survived, I had already decided to mount a Big Red Bee in the nose cone for the next time. But, alas... it didn't. The quantum tubing crimped just forward of one of the fins, and as mentioned before, the transition shattered.

But, it did look oh, so good going up!

BTW - I found it much easier to slip the nylon strap under the centering ring (and yes, I also had to enlarge the hole a bit to take the strap) and then epoxy the centering ring and the strap onto the motor tube.

 

[JAL3]

Yes, but it's no match for an airport taxiway!

I flew my MR-1 with Houston's Tripoli-002 in December down at their Hearne (TX) airport launch site. I had read enough build threads and reviews to know that I wanted to ditch the brass launch lug, so I substituted a 1/4 paper lug. Launch day was a bit windy, and the first time the MR-1 was on the pad, a little gust of wind levered the rocket at the lug, and it promptly popped off. Ah, well.. a bit of sandpaper and a new lug epoxied on with 5-min epoxy, and we were set to go.

Maiden flight with a Roadrunner G-80 went well. It landed fairly close to the pad.. about 75 yards away after a nice flight to about 700 feet.

Next flight up on a Cessaroni H-153 and everyone lost sight of it as it took off like the proverbial scalded bandit. A couple of folks said they heard the ejection event, but no one.. and that was about 8-9 people all looking.. no one saw it deploy or land. No one heard a "screeeeeee-thunk", so hopefully it came in under chute.

One of the folks who left after my wife and I had already started back to Fort Worth, saw some pieces of white plastic on the taxiway as they were headed out, and then saw the rocket in the grass by the taxiway - minus the white plastic transition (the debris on the taxiway).

This was my first experience with the PVC ... errr.. Quantum tubing. I'm not impressed with its ability to absorb an impact on a hard surface, so if that's even remotely possible where you fly yours, think twice.

This is a small rocket, and it needs a tracker in it if you're going to fly it on anything larger than a G, because it can scoot out of sight in a flash. If it had survived, I had already decided to mount a Big Red Bee in the nose cone for the next time. But, alas... it didn't. The quantum tubing crimped just forward of one of the fins, and as mentioned before, the transition shattered.

But, it did look oh, so good going up!

BTW - I found it much easier to slip the nylon strap under the centering ring (and yes, I also had to enlarge the hole a bit to take the strap) and then epoxy the centering ring and the strap onto the motor tube.

Thanks for the revelation.

When I get to fly it, I'll either be up in the hill country or in the desert around Ft. Stockton so runways are not an issue. It looks like finding the rocket may be though. I've never used tracking devices and may need to give some thought to that.

 

[lessgravity]

Mine has about 25+ flights on it. I love to fly it in the F-G range. Anything else and I may not recover it at our club field.
This is one of my favorite rockets.

 

[JAL3]

Mine has about 25+ flights on it. I love to fly it in the F-G range. Anything else and I may not recover it at our club field.
This is one of my favorite rockets.

I've heard that people tend to like it.

This is my first PML kit. So far I'm pleased and glad I didn't get the 38mm version since it seems to be a performer.

 

[lessgravity]

So far I'm pleased and glad I didn't get the 38mm version since it seems to be a performer.

I did get the 38mm version but haven't launched it without the 29mm adapter.
Can you imagine ...it sims to nearly 10000 feet on a J350.
Here is mine laying amongst some other mid to HPR rockets (you can see the 29mm adapter in it).

 

[n3tjm]

I appreciate the tip.

I was planning on asking a question related to this but forgot.

I'd like to use a linear rail button, or failing that, standard rail buttons but have not come up with a way to make it work. If I can't, I'll certainly keep fiberglass in mind. THat will be my first fiberglass work.

Here is what I did with mine. I used a standard rail button set up for the top part of the rocket, drilling and screwing the bolt right into the forward shoulder of the transition. For the rail button between the fins, I simply used a longer bolt, and made a spacer out of a bic pen. Works very well. So far I have flown my MR-1 on several motors, F40, F52, G185

 

[lessgravity]

Here is what I did with mine. I used a standard rail button set up for the top part of the rocket, drilling and screwing the bolt right into the forward shoulder of the transition. For the rail button between the fins, I simply used a longer bolt, and made a spacer out of a bic pen. Works very well. So far I have flown my MR-1 on several motors, F40, F52, G185

I just recently converted my to rail buttons after having issues with the brass lug. I prefer rail buttons and agree that this is a positive hack.

 

[JAL3]

Here is what I did with mine. I used a standard rail button set up for the top part of the rocket, drilling and screwing the bolt right into the forward shoulder of the transition. For the rail button between the fins, I simply used a longer bolt, and made a spacer out of a bic pen. Works very well. So far I have flown my MR-1 on several motors, F40, F52, G185

That looks workable and I may go with something similar if my current hare-brained scheme does not work out.

When I had posted my earlier question I had read the instructions but had not taken the transition out of the bag. Now that I have, I have a solution (I hope) that I will be posting in a little bit. It uses the linear lug I have grown fond of using.

 

[JAL3]

I got the third fin epoxied into place today and it looks to have gone on straight.

 

[AndyC]

Not that I'm recommending it, but a fellow at our club certified with an MR1 on an I161 motor. If I remember correctly it was predicted to go 3000-4000'. It was the only motor our vendor had in stock in any case, and he was itching to go. Man, talk about a don't blink flight - at least for the first 0.5 seconds - after that it was gone. Lucky for him our prefect somehow kept his eye on it. He got incredibly lucky and got it back along with his cert in the end.

Looks like a great kit - have fun flying it. Maybe something nice and smokey like an H97J would make keeping an eye on it easier?

 

[JAL3]

With the fins in place, I used the tape tabs put on the aft centering ring earlier to pull the ring out. This gave access to the joints between the fins and motor tube and the fins and inner BT. Small batches of epoxy were mixed and a long swap was used to fillet the inner and outer joints. At the same time, the outside of the BT was filleted to the fins. THe epoxy fillets were smoothed by a glove clad finger dipped in alcohol.

At this point I need to 'fess up to a blunder. My thought was that the inner fillets did not need to be pretty and I was kind of messy applying them. This led to later problems in getting the aft centering ring back in place. I ground the blobs down as best I could but the ring still wouldn't go in. I used a sander to remove more from the outside and my finger with some sandpaper to work on the inside. It helped but not enough. Then I got the bonehead idea of forcing it. I used a rubber headed mallet to get it started and it did start. It was also aparent that it was never coming out again. I was commited. Then I got dumber. I placed the handle pieces of a pair of piers on the fing and rapped the other end with the mallet. This drove the ring down but also split the wood. It wasn't split enought to be removed but it was pretty awful looking. I finally finished seating the ring with the mallet and pliers method and then covered it up with epoxy. Its ugly but should work. Besides, it is my hope that the rocket will be moving too fast for anyone to notice when that end is on display.

The embarassment factor is too high for photos of this stage of construction.

 

[JAL3]

Not that I'm recommending it, but a fellow at our club certified with an MR1 on an I161 motor. If I remember correctly it was predicted to go 3000-4000'. It was the only motor our vendor had in stock in any case, and he was itching to go. Man, talk about a don't blink flight - at least for the first 0.5 seconds - after that it was gone. Lucky for him our prefect somehow kept his eye on it. He got incredibly lucky and got it back along with his cert in the end.

Looks like a great kit - have fun flying it. Maybe something nice and smokey like an H97J would make keeping an eye on it easier?

I need to find some 29mm Hs, preferably smokey ones.

I don't have a LEUP and I need to find a launch I can get to that will have an on site vendor. Then I need to find out what line that vendor carries. THen I need to buy the hardware.

Wifey is going to be mad...

 

[JAL3]

Piston construction began with sanding down the piston bulkhead so that it would slip into the piston tube WITHOUT using a mallet. This did not take too long with a belt sander. The nylon strap attached to the motor mount was then fished through the provided slot, passed through a D ring and then passed back through the slot and snugged up. Epoxy was then used to bond the strap in place.

 

[JAL3]

When the epoxy around the strap had dried, the piston bulhead was inserted into the piston tube and epoxied into place with fillets on both sides.

 

[JAL3]

The transition section still needed to be put together. It had to be epoxied to a 1" length of Qunatum tubing that would recieve the nose cone. I scruffed up the plastic with sandpaper and the epoxied it into place.

 

[JAL3]

The transition was slid onto the BT down to the fins. The strap from the nose cone was then pushed down into the BT on top of the inserted piston and the nose cone settled around the top of the BT as far down as it would go. The transition was then moved up until it housed the lower end of the cone and a line was marked on the BT and the transition slid back down. A fing of epoxy was then applied at the line and the transition slid back into place. You must be careful at this point to make sure that the nose cone does not get bonded.


NOTE: he asymmetry in the photo is due to the rocket not being perfectly plub to begin with and the lug standoff. It really is straight.

 

[JAL3]

All that was left, except for the lug, was to attach the strap from the nose cone to the top of the piston.