ProBroJoe

Due to the generosity of one of the members here in the making of my "SureStart backplate - to - beam style engine mount", my DNU now sports a Norvel .049. I won't tell you who did it for me because I don't want them inundated with requests, but a big thank you goes out (you know who you are)!

Oh, for those who are interested in seeing a video of what a DNU can do with a Norvel on the nose, you can check it out here:

http://home.comcast.net/~webster_eng...u-w-norvel.wmv


-Joe

ptulmer

My Feedback: (5)

It really zings along with a Norvel don't it! I was flying mine with a Norvel BM .061 R/C earlier. What prop are you using? My cut-down MAS 6x3 (to 5x3) doesn't really seem to be cutting it. Next try may be an APC 5.7x3.

BTW, the mount looks fantastic!

Japanman

PT,
If you have a spare one, try cutting the apc 5.7x3 down to 5x3. On my firecracker it let the norvel pick up 2 thousand or so rpm and the power AND thrust went up a lot.

J.M

jlkonn

My Feedback: (1)

I have a DNU kit ordered from Select Hobbies.
The performance of yours is quite spectacular.
Will a stock Sure Start fly it?
I ordered a couple from Cox recently.
How are they in from the factory condition?
Thanks!
JLK

Tee Bee

Whoa! That thing cooks.

ptulmer

My Feedback: (5)

JLK, sure thing. Joe and I both were flying with Surestarts before. The SS's need to be opened and cleaned before being ran. So far I've had one really great runner and a bunch of good runners. No real bad ones. That's out of six or so.

ProBroJoe

Hey PT... I'm running the exact same Cox 5x3 "rubber ducky" that I've using for the past two years! I have a coupla APC 5.7x3s that I'll prolly try out, but it's kinda hard to mess with success! A cut-down 5.7x3? Hmmmm, may have to give that a whirl - ooops, sorry, bad pun....

In another thread PT, you mentioned that yours didn't launch very solid with a 5x3? What's up with that? Even with the Sure Start, it was up and moving on out before I could get my right hand back onto the stick!

JLK - a stock Sure Start will fly it just fine, it won't be as "spirited" as with a hotter engine, but it does well.

If you have the means, it would be a good idea to check and adjust (if necessary) the rod to piston ball socket joint. On a lot of the Sure Starts they've come from the factory quite loose. Details on this (and even plans for making your own adjustment tool) have been covered here before. A forum search here should come up with a few hits...

Hope this helps,

-Joe

ptulmer

My Feedback: (5)

Joe, I hate to admit it in public, but I don't typically do bench break-ins. What fun is that?! It's been windy as heck, so I haven't even got the .061 broke in yet! Launches are solidifying. Now I want more speed and thrust. The prop I use for break-in is a MAS 6x3 cut to 5x3. Not the best prop in the world for thrust or speed. It doesn't load the engine much at all. This weekend it finally got out of the four-strokin' and into a nice whine.

rainedave

My Feedback: (1)

I have used APC 5.7x3's for 18 years on .049's and always thought they were about the best readily available props. Recently, I splurged on a couple of the APC 5x3's (they're about twice the price for some reason) and now I have a new favorite 1/2A sport prop. They are absolutely worth trying.

http://www2.towerhobbies.com/cgi-bin...?&I=LXFGX2&P=7

David

SGC

PT, try a MAS 6x3.5 cut to between 5 -5 1/4"
Stewart

flyinrog

My Feedback: (1)

cool video Joe, you do know you can buy those engine mounts right?...I cut out a kit of a DNU a good while back but for some reason never built it...well I went searchin and found most of the parts..guess I should go ahead and build it before I lose anymore parts.....Rog

ProBroJoe

Rog, the mount I had made has the exact hole pattern for a product engine/Killer Bee/SureStart backplate. My DNU already has blind nuts installed in the firewall for the Sure Start, and I thought that a mount that would bolt right up to those holes would be just the ticket. The Dave Brown, or Dubro beam mounts have a wildly different mounting arrangement and would have required drilling new holes. Sooooo, long story short, swapping engines back and forth between SSs/TDs/Norvels/Wasps is now a simple two minute affair. There is another member here on RCU that is considering taking the idea and producing glass filled polyurethane mounts that accomplishes the same thing, but I'll let them come forward when they're ready. (I started a thread about this idea about a month or so ago.)

Of course our clever friend Combatpigg had the best idea - simply fill the old holes with toothpicks and drill new holes for use with #2 sheet metal screws - forget the blind nuts!

Now, I wonder how the TD .051 will fly the DNU?

ptulmer

My Feedback: (5)

Joe, I've got the plug about 90% ready. It took about five minutes on the bandsaw to abandon that idea. The milling head on the Smithy was the ticket! The wax machined so smoothly and wasn't easily marred by the vise that the process was a real pleasure. Just so you know, I've got no intention of making them to sell. It's your design and I'm happy you have let me use it to learn on. Secondly, it would take too friggin' long to make any money off of. But since it seems like you're ok with spreading the love a little, I can make some for our little group here. (It won't be any time too soon. I fully expect to make a mistake soon and have to start over at least once.)

Flyswatter put a TD .049 on his. Bring a change of underwear to the field. It was ballistic. The TD is superior to any Norvel except maybe the late model AME .061.

flyinrog

My Feedback: (1)

Normally I'd be the first greedy little half A er to shout .."I want one".. but in most 1/2a applications, I go with the screw it to the firewall screws..but Patrick, it is a nice piece of work...Rog

ptulmer

My Feedback: (5)

Sorry Rog, I didn't make the aluminum ones. I'm struggling like hell just making a wax one! The aluminum one was made by a very experienced machinist.

ProBroJoe

Zooooooooom.......

Oh man, fun stuff - I'm just getting back from about eight flights with the DNU. I was a little brave and upped the Nitro to 25% and threw on an APC 5x3 per (rainedave's recommendation). RPMs jumped from 18,500 to 20,500... The first thing that I noticed about this prop is that it's a lot quieter than the Cox 5x3. However, it's not as fast as I expected it to be - it's about on par for speed with the Cox prop. Now the good news is that this prop has a bunch more thrust - she now does BIG loops, Split "S"s, & Immelmans with ease and climbs like the proverbial bat out of hell without losing a bunch of RPM in the process.

So, tell me, about this Sig 1/2A fuel - just how much oil is in this stuff? I'm not used to cleaning that much goo off of EVERYTHING! (My previous fuel was Morgan Omega 15% with 4 oz of castor added to the gallon.) I'm guessing the Sig is pure castor and that's what I'm dealing with, right? Sure smells nice though, whatta they do, put perfume in this stuff?

skaliwag

My Feedback: (1)

Yep .. They oh-da-rize it with Eau De Parfum 1/2A

Tee Bee

The oil is half synth/half castor. It's what I've been using lately as well.

rainedave

My Feedback: (1)

Joe, I saw basically the same results when I switched to the APC 5x3; a lot more thrust. This prop has also made my reedy needle valves noticeably less touchy. The engines run at peak rpm over a wider range than they ever did with the APC 5.7x3's. This is great because if the needle valve rotates a little in flight you don't loose your setting. They are definitely worth the extra $2.10.

Now, I'm wondering how the APC 6.3x4 would do on my Norvel .074. It's not going to do any harm to try it. Logic suggests more speed/less thrust, but I have found that what applies to larger engines and props often doesn't hold true with 1/2A engines.

David