Richter Recker Questions

[Johnnie]

...I could surf a little to find it here on the TRF, or do the TRF search thingy, but what the heck, I thought I would just start another R.R. thread.

So I am building this Fliskit with my son, and I am building per the instructions, to use the 3 D motor configuration. I stuffed the motor mount with tissue soaked in Elmers glue, and mounted into the 1st tube, and it dawned on me, this R.R. might be getting a little on the heavy side.

So my question to the group is: Building strong and light, what kind of altitude can I expect to get from the R.R. on 3 D12's?

On my own personal R.R. I had planned on moding the mounts to accept (3) E9's...what alt might I expect? hmmmm

I do have rocsim, and plan to sim it out, but these ?'s are for the ones that have flown these combos in their RR's. I priced out some E30's, that the local Hobbytown USA has plenty of, and one flight might cost me $33

One other mod, my son wants all of his fins to match. If you have an RR, then you know what I am referring too, as the RR has (2) wide fins, and (2) narrow fins. He wants all the fins to be wide...I have a gut feeling this is going to add to the weight of the design.

All in all, I don't want to have to fly this thing on D12-0's in order to recover safely. any RR advice from the experienced RR fliers out there??

 

[n3tjm]

The RR flies pretty high with the 3 D12 cluster.. I know somewhere on the forum somebody has the altitude simeed, but I seen the beast fly several times on 2 D12 and 3 E9 clusters (3 E9's is a G motor! )

Don't worry about the stability... the rocket it stable with 3 E9 motors, which stick out 1" more from the rear. Also, making all four fins large will actually increase stability.

Have Fun

 

[Johnnie]

Another mod my son has agreed on, was the addition of rail buttons. I have launched the Mean Machine on the 3/16" rod, and it was a 'waiver' to the crowd before it flew...show-off! The 1/4" rod is barely better than the 3/16" so I will go with a rail to make sure the slow majestic take-off is straight and true.

I have become a firm believer in the button...

 

[Rocketman248]

The RR doesn't take off as slow as you would think. It's pretty quick. My uncle flew his at NARAM. It's pretty zippy for it's size. It's really cool to be able to fly something that big up close.

 

[jflis]

well, some answers...

i don't have precise altitudes because I've never SIMd the RR but she *does* scoot on 3-D12's. I would guess better than 600 feet, maybe even 900

3-E9's will send her up well over 1000 feet, but she won't go as fast (not as much kick at liftoff with the lower peak thrust of an E)

Also, if you've built the thing to take D12's (set the engine block for short 24mm motors) you can *still* fly it with E9 motors. I do it all the time now. Just install the motors till they hit the motor block (if you have the engine hooks installed, they're fine, they just won't engage), then secure the motors via "friction fit" The attached picture shows my RR preped with E9's. gotta love duct tape

Making all 4 fins WIDE will not be a problem. What little weight they add wouldn't amount to a flea-bite compaired to the overall model. The RR has several calipers of stability and is not bothered by such modest modifications.

The use of rail buttons is a fine modification. I've seen 2 RR's modified in this way. The only problem (from my point of view) is that this often restricts you to pads that are further away. I agree with Nick's comment about one of the nice things with the Richter Recker is that you can see a 7+foot rocket launch from the near pads

jim

 

[Larry]

I like the fins the way they are. Gives it that unique look. I have a couple of modificatiions myself, but I'm waiting to see if they work first.
Larry

 

[Johnnie]

600 to 900 feet on D12's sounds excellent... I knew that E9's did not have the Oompah! that the D12's have, but the longer burn times multiplied by 3 should make for a nice long ride over the 1000 foot mark...

I was not worried so much about the stability of the rocket with all large fins, as much as I was about the added weight affecting the ability of the D12's...Heck Balsa can't possibly add that much weight. I like all three options for the fin design, but I'll go with what my son wants as it is his rocket. If he wants all the larger fins, then so be it. I will try to post pics of any progress.

One concern I did have was the weight of the glue soaked tissue in the motor can assembly. I thought I had added to much glue, thereby adding on extra weight, but the glue has since dried, and I believe alot of the weight has evaporated away from the Elmers white glue. Anyways, it felt lighter to me this morning.

 

[jflis]

well, when Elmers *dries*, most of what is happening is the water is evaporating from it, and that is what most of the weight of elmers is (water)

I;ve seen a Richter Recker glassed, nose to tail and it flew fine on D12's, so I wouldn't worry about it.

I will, however, point out that the loaded weight of the Richter Recker, built STOCK with D12-3's is about 15.8 oz (making it the largest model rocket under a pound (hence not needing any special waiver))

Going to E9's or modifying the kit (glassing) in a way that adds much extra weight (1/4 oz) can throw you over the 1 pound limit.

jim

 

[eugenefl]

Originally posted by Johnnierkt
All in all, I don't want to have to fly this thing on D12-0's in order to recover safely. any RR advice from the experienced RR fliers out there??

Well, D12-0s won't give you a safe recovery. Might want to use D12-3s instead if it's on the heavy side.

I've seen only one RR fly so far. Jason (jetra2) built his with fiberglassed fins and used rail buttons. The added weight sure didn't seem to affect the RR at all. His rocket lofted very high on E9s. I do believe he also did a flight on D12s. Even with a long delay on D12s the chutes would have had plenty of time to deploy and recover the rocket safely. I must admit that the cluster of 3 E9s is quite a sound to hear.

 

[Rocketman35]

What is the body tube size of the RR? It looks like about a minimum dia for a 3 clustered config like pictued in JimsF's picture...

EDIT---Does the RR come as a clustered bird? need more info on the rocket...I'll look at the reviews on emrr.
Guess I'll look on Jims site too
BTW Jim i received the BT 50's and motor tubes i ordered, Thanks

 

[Johnnie]

The RR is 2.217" dia. per the card stock insert from the kit.

 

[jflis]

yep, it's classic BT-70

2.217" OD, 2.175" ID

Each tube is 17.5" long, there are 5 tubes in the Richter Recker.

A 24mm, 3 motor cluster made with standard BT-50 tubing (.013" wall thickness with an OD of 0.976") is a *shade* too small to fit in the BT-70.

Therefore, in the Richter Recker, we provide a BT-69 tube with an OD to fit inside the BT-70 and an ID to fit the outer area of the 3 motor cluster.

Makes for a very strong and long lasting cluster motor mount.

ALso, to answer Rocketman35's question, yes the Richter Recker comes as a clustered bird. You can find it on our site under "Skill Level 3" rockets (under "rockets by skill level") or under "Cluster" (under "rockets by type)

jim

 

[Johnnie]

Jim,

Do you recall off hand what the Ogive is on the nosecone? I will spend some time Rocsim-ing the Richter Recker today...

 

[jflis]

that's a tough one...

the NCB-70AJ isn't a true Ogive... For SIMing purposes, you could use 2:1

It's an Ogive with a rounded point would be the best description.

hope this helps.
jim

 

[Johnnie]

Thanks Jim,

Rocsim is forgiving, in that it draws your cones for you. You just give it length and dia, and wala!...

so anyways, rocsim I do not believe accounts for glue...how could it? Allthough it does take into account the outer parts of the rocket being finished...painted I presume.

So here is what Rocsim is telling me about the Richter Recker:

No motors = 10.690 oz.

w/ D12's = 15.325 oz.

w/ E9's = 17.145 oz.

This is right in line with what you have already stated in that this rocket does not need any speacial paperwork if flown on D12's, as it's mass is under 1 pound. With E9's, the weight does go over a pound, just a little bit...

Now for the good stuff:

D12's = 943.46 ft alt.

E9's = 1734.71 ft. alt.

E18's (RMS) = 2184.23 ft. alt.

F24's (RMS) = 2493 ft. alt.

E30's (SU) = 2133.27 ft. alt

I'm gonna have fun with this one, I can tell

 

[Johnnie]

...so without the fins mounted yet, the main assembly weighs 11.5 oz.

I do tend to over build, so my birds put on weight.

 

[cls]

don't forget, much good information about many rockets is available from EMRR, https://www.rocketreviews.com/. a rocksim file for Richter Recker is there.

(hope this helps and isn't too late for this thread...)