MRC's Iron Man is a GREAT kit!

True, but as John mentioned, that was a Concept Two kit. Apparently the first concept wasn't given much thought.

__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Centuri Mini Dactyl Estes F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark

Well, with respect, I have to disagree. The earlier MRC kits weren't over the top in design or quality, but having said that, they weren't as bad as they're being made out to be on this thread. The tubes were comparable to Estes tubes and slightly less robust than those found in the Centuri kits of that era. The biggest knock against them was the lack of imagination that went into them. 3FNC and 4FNC about says it. Still, these kits usually go for a bargain price when they come up on Ebay, and I think we would be doing a disservice to anyone with a small rocketry budget by scaring them away from them. In my opinion they can be a great first kit for a kid on a budget.

Joe

Attached Thumbnails

   

Joe,

As long as these kits sell for bargain prices I see your point. Problem is, a kid on a budget is not going to be shopping on eBay. And a cheap kit, plus another $5 or so for shipping, is perhaps going to make that an OK deal, at best.

I'd be more inclined to direct a kid to some place like Hobby Lobby (or Michaels) and have one of his parents use a 40% off coupon to get a bargain. But this has its problems, too, with some Hobby Lobbys/Michaels either not carrying Estes, or having a really limited selection of kits that require building.

Maybe the compromise is the get someone started on a RTF or E2X kit from Hobby Lobby/Michaels, and then when ready for a kit you actually build, pay a little more and go to a hobby store that carries a bigger selection. Our town has a well-stocked HobbyTown, but the slight downside for that kid on a budget is that he will pay full price for that selection. I call it a slight downside because I'm glad we have a hobby store that does carry a good selection of Estes products, but not everyone is going to see it that way especially the kid.

__________________
Lee Reep
NAR 55948

Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor
In the Paint Shop: Nothing! Too cold!
Launch-Ready: Farside-X, Maxi Honest John, Super Scamp

Nothing about these tubes were remotely comparable to anything Estes has ever kitted. I flew the XR-20 on a C6-5 yesterday. First flight. It flew great, but the ejection charge burned away the body tube just above the motor mount. The only reason it retained any structural integrity at all is because of the decals that I had to make for it.

__________________
Bill Eichelberger
NAR 79563

http://wallyum.blogspot.com/

I miss being SAM 0058

Build floor: Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc Starfighter Scorpion Centuri Mini Dactyl Estes F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark

I think they were closer to a couple sheets of toilet paper than an Estes body tube. I swear the body tube flexed one day when I farted beside my Wildfire kit.

__________________
I love sanding.

I HATE it when that happens ...

__________________
Lee Reep
NAR 55948

Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor
In the Paint Shop: Nothing! Too cold!
Launch-Ready: Farside-X, Maxi Honest John, Super Scamp

OK, so I opened the little MRC Starfire kit (for a photo, see my post above) and weighed the tube. I also weighed an Estes BT-20 tube from another opened Estes kit. The Estes tube was 6.5" long and weighed 0.10 oz. The MRC tube was 9.0" long and weighed...............0.15 oz!

So it's not a difference in weight...........the tubes weigh almost the exact same amount expressed in oz/in of length.

However, I did notice a real difference in quality of construction. The Estes tube was more precisely wound. There is a noticeable gap in the glassine layer on the MRC tube (which really lowers rigidity and accounts for the comments by others above on the 'bendy' tubes). These MRC tubes remind me of the old Competition Model Rockets tubes. I wouldn't be surprised if both companies used the same supplier.

So I respectfully bow to the wisdom of the majority............these kits were a notch down from Estes in quality. I can't account for the burning on ejection reported by Wallyum (Bill) above............I checked the inside of the MRC tube to determine whether it might be a little rougher or more porous (and therefore easier to ignite by the ejection charge) but I can't see any real difference. I wonder if that particular engine might have had a whopper ejection charge.

Joe

Attached Thumbnails

     

When I read Bill's blog I thought of what I've seen with Aerotech 18mm SU composites cooking tubes with their flamethrower ejection charges. Haven't seen that particular problem from BP motors - which is not to say that it doesn't happen.....

__________________
Bernard Cawley
NAR 89040 L1 - Life Member
SAM 0061
AMA 42160
KG7AIE

The "hibachi effect" which you refer to as "flamethrower ejection charges" is actually the burning of of the remainder of the delay grain... In composite motors, the delay grain continues to burn for a number of seconds after the gunpowder ejection charge has been ignited and gone off... The delay grain hot combustion gases vent thru the easiest route out of the casing, which is forward out the ejection charge well of the casing rather than back thru the labyrinth of detritus and crud usually blocking the narrow nozzle orifice... Thus roasting the tube interior...

On bp motors the delay grain burns across a broader, rounder front up the length of the casing... When the center burns thru, it ignites the ejection charge, which then blows out the laundry... There is usually a ring of bp let burning outward from the center after the ejection charge fires, but it burns out quickly in most cases... Hence little hibachi effect... Again, is easier for the hot gases to escape out the front of the now spent casing than our the labyrinth of crud blocking the narrow nozzle orifice farther away in the back of the casing... Path of least resistance...

If you watch static test motor burn slo-mo footage on YouTube, you'll see a brief flicker of flame after the ejection charge blows... That's the remainder of the delay grain burning of and venting out the casing front, which is the cause of the hibachi effect...

Later! OL JR

__________________
The X-87B Cruise Basselope-- THE Ultimate Weapon in the arsenal of Homeland Security and only $52 million per round!