flyinrog

My Feedback: (1)

I put the .074 on my JK trainer,,it has a 7 x 4 on it ,1st time Ive started it up in a while..started right up and ran fine but it seemed to be under a load not revving like I thought it should,,is this too much prop or will it unload in the air? should I go with a smaller prop.pitch...?..Rog

SST

My Feedback: (2)

I use a Cox gray 7X3.5 on mine and love it.

combatpigg

My Feedback: (3)

Mine kicks A with an APC 7-3. It seems loaded down by the COX prop, but I haven't tried cutting it down to 6.5" yet, I think that will pay dividends on the right airframe.

rrragmanliam

My Feedback: (1)

I use a MAS 7x3. I started w/ a 7x4 and had the same experience you did. the 7x3 made a big difference. BTW I use 30% nitro. Too bad no one makes a 7x2

Darren

MikeSell

My Feedback: (2)

You don't specify which brand 7x4 you have on it. APC props of a given size require less power to spin at a given rpm because of the reduced blade area at the tips but that also reduces the thrust at that same RPM. A MA (windsor) has much more squared tips and does not rev as freely but provides more thrust at that same given rpm. The Ma does unpitch a little as it is not as rigid as the APC or the Cox gray. The Cox gray is very wide bladed and square tipped and also very rigid. The engine will not rev as high with one of these on it but will provide much more thrust at that same rpm.
If you can peak the engine with the prop turning over 15,000 rpm static I think you are doing fine. It will unload some in the air. Mine turn a Cox gray 7x3.5 at 16,000. They cannot spin a gilbert 7x3 over 13,000 rpm.
Remember you are flying a trainer. You want thrust and slower airspeed. In my experience wide square blades do better in this application. Narrower shorter blades do better in slippery high speed planes.

flyinrog

My Feedback: (1)

Well, I 'm not too familiar with the engine, I drove it into some carolina clay first time out last summer...I didnt check the rpm's ,it just sounds like its lugging..I did find a master airscrew 7 x 3 that I can try,,whats on it now? medium gray, very thick, think its APC but not sure, the 7 x 4 is the same one that was on the Norvel .15 should be ok on that, havent even tried to run it yet, got it at a swap shop....Rog

rrragmanliam

My Feedback: (1)

Rog, If you have a MAS 7x3, use it you wont be disapointed. Like Mike was saying it has a wider blade area than the APC props so you will have plenty of thrust.

Darren

Bipe Flyer

I'm a big fan of APC props and I use them on just about everyting, but I prefer the MA 7X3 on the Norvel .074 because it provides more thrust.

cali_dream

I have always flown my norvel .074's with a 7x3 or smaller. We actually did some crazy testing, running it with props as large as 8x4! With a lot of shims it actually handled that prop, but I'm not so sure about a hot hot day.

Anyway, I flew one of our UCAN-2 ARFs for a summer, can't say how many times I crashed it by the way. It absolutely loved a 6x4, I think I flew .074's with 6x4 props more than any other prop. Worth trying especially on a hot summer day when the engine is more sensitive to load. 7x3 was my next choice.

I've always been a "what's in the field box" kinda guy when it comes to props, so the other guys here probably know more than me anyway.

Ed Stevens
NORVEL, Ltd.

Dukester

My Feedback: (31)

Ed,

You sound like me. Hmmm, well I know its only a baby bee, but what the heck, the only thing in here is the 8X3. (RPMs for nothing, but boy did it look and sound cool).

Duke

2fast4u

My Feedback: (5)

cali_dream Dude, it's been a long time since I heard from you. I have been and will always be NORVEL's biggest fan in Arkansas. You really need to come to SMALL again.

flyinrog

My Feedback: (1)

Got the 7 x 3 on it tonight, it spools up really nice with it on, didnt get to tach it as I had to hold it while it was running, now if it would just stop raining one day, I could actually test fly it again...Rog

cali_dream

To answer 2fast4U, I have been a lot less active with NORVEL for a pretty long time until the last few months. For the last three years, NORVEL has really been working on moving to another level of production technology and product development. Our new .40 is our first proud achievement, it's dual BB, etc. deluxe. We are currently closing out a number of our classic 1/2A engines, for example the A6 will not be produced for the rest of this year and we have only a small supply left. We will be closing out some of the .15-.25 engines next.

We are still making the most popular motors, like the .074, I expect to get a new batch of those in a couple weeks.

There will be something new for the SMALL group in our engine line, hopefully by the end of the year, sorry but no amount of begging will get me to talk . . .

Bipe Flyer

I wont beg for info on whatever the new engine is, but put me on the waiting list 'cause I'm going to want a couple.

I hope it has a part number like B2R.

ZAGNUT

My Feedback: (1)

for the most part you're right....BUT my experience shows that the MAS 7x4 will turn faster and be quieter than the APC 7x4 on a given engine....well, at least up in the low 20K region.


dave

Digger-RCU

I'll mention the prop I really like on the 074 because it has not been listed yet.

APC 6.3x4

I have consistantly found this prop to hook up very well.
It's kind of a specialty prop. I always have to special order it.

Very nice thrust, with good speed, and keeps the engine nice and cool.

My Herr Mustang, and my HOB p-47 both really like it.

Randy (Digger) Birt

combatpigg

My Feedback: (3)

DIGGER, I will bet that is a good prop, I haven't noticed it.

ROG, If your 074 seems sluggish, keep running it, because if it is like mine it needed 2 quarts of fuel before it loosens up and turns into a screamer.

2fast4u

My Feedback: (5)

PLEASE, PLEASE, PLEASE......[] ? Ok I'll wait...... [:@]

Hay DIGGER...... Nice medical save at SMALL dude. You did a great job fixin up my buddy's arm after the prop got to it. It was cool how you leaped into action.

flyinrog

My Feedback: (1)

We went a test flyin today, poor trainer has so many repairs even the .074 just barely flew it around like a park flyer, twice after starting, the engine would drop to 1/2 throttle after the toss, turn out it was too lean?, I richened it up a click or two ( I run Norvel %35 nitro) and had two great flights, so the 7 x 3 worked fine but man,just as an example the engine mount is a piece of 1/2 pine plank and the wing brace is 1/4 inch 1/4"x1/4" x 14" oak plywood, it flys but its touchy and slow, hard to trim in any wind at all,,turns left better than right, course that could be me..the tank I put on top of the fuse leans forward as soon as I throw it so it angles up in the back, so it does fly longer than the c/l tank but not much, I can do loops but only early on in the tank, I can scoop out some foam and fix that though...I gotta start on another project.....BUT, the .074...sweeeeeeet engine, quiet , gotta love this thing,acted like it could run all day long, sure does spray out the goop though gotta put an exhaust deflector of some kind on there, Hey whats another oz or two?...Rog

lwr_

APC 7-3!!!!!!!!!!

V. Sharp

Hey, Fellas --

I know this is basically about Norvel .074 props, (I have one, haven't run it yet) but my question is -- where can you get Cox grey props?? Specifically 6X3 and 5 1/2X4? I have a 24" 2-channel biplane with a double ported golden bee on it, and am almost out of props.
Help, Please!!

By the way, the biplane was built in 1978, and I flew it again last Sunday!

Thanks,

Vaughan Sharp

frank99

My Feedback: (29)

2f my nitro rascal will be in friday would the nor.074 use the 7x3 as a start[8D] thanks frank

combatpigg

My Feedback: (3)

Get in touch with COX directly.

MikeSell

My Feedback: (2)

V sharp:
I hope you find a source for the gray assortment. I've tried several cox suppliers but have not found any source for new Grays. They have all told me that they were discontinued. I fly cox grays on all my .049-.074s exclusively. I fly their 8x4 gray on my .15 and .19 engines. My only sources are the auction sites and swap meets. I hope my casche holds for several more years.
PM me if you find a source.