LIMITED-B Prop Tests please ?

This is the thread to aid in development of new ideas and classes. Post working rules and gather feedback!

Moderator: hbartel

Grun-Herz-Geschwader
Posts: 213
Joined: Fri Feb 15, 2002 8:41 am
Location: Village Mills
Contact:

Post by Grun-Herz-Geschwader »

Ok today it was 90 degress, 76% humidity, 20ft above sea level
Lanier Slasher, Norvel .25, Kombat Kan, mousse can header, Ritch's Brew 15%, 22%castor, APC 10 x 3 14800 -14600 rpms, 6 flights.
I wanted to try the stock muffler, but it sticks past the guard on the Slasher, and I ve broken two of them in two days, the header works great though!

Ich bin der vorbote des todes!
Admin
Posts: 309
Joined: Sun Dec 24, 2000 1:00 am
Location: USA
Contact:

Post by Admin »

Sunday I tried a 10x3 APC on a AVENGER 964 with one of my Irvines with UltraThrust using 15% Powermaster with 22% oil. I got to about 14.2K before it got hot and fell back to around 11K. The day was about 80 degrees with ~40% humidity. Very nice day… Same motor moments before with a 9x4 MAS turned 19.4K.

I let it cool, refired, and launched about 13K. Good pull and about 50 feet out it came on the pipe. Side by side with a buddies OS FX .25 UltraThrust Powered AVENGER 964 and the 10X3 APC was noticeably faster. Hard pull lugged the motor down and came off the pipe. It was fast enough to cause flutter in ailerons which did not happen the 3 rounds of combat I flew following with a 9x4 MAS.

I meant to throw in a stock muffler but forgot. Maybe this weekend I can get some tests done with a stock muffler.

This motor has had the crank and exhaust timing opened up. My friend’s FX is stock and I hope to get him to try a 10x3 APC for comparisons.

CONCLUSION: I think the stock muffler is definitely a must. I thought the 10x3 may keep the motor loaded down, that was not the case…

A.J. Seaholm
TEAMseaholm.com
[url="mailto:seaholm@teamseaholm.com"]seaholm@teamseaholm.com[/url]
sgilkey
Posts: 2351
Joined: Mon Mar 19, 2001 8:26 am

Post by sgilkey »

Brian and I had a chance to do some more testing, this time on an OS 28F, stock but in excellent condition, stock muffler, large carb:

MA 10x4 15.1
APC 10x3 15.4

This was with Cool Power 15% and a random, used glow plug. I usually find Cool Power to give lower rpm than other fuels such as Powermaster, Sig, or Ritch's brew, plus I did no experimentation with glow plugs. I think that with tweaking, this engine would bust out of the 15.5k limit, but probably not by much. weather was low 80s and humid.

We also re-tested the norvel with a stock, non-reamed tailpipe. Cool Power 15%:

MA 10x4 14.6
APC 10x3 14.8

no way to account for atmospheric differences, but we see about 200-300 rpm reduction from the reamed/trimmed tailpipe. Fuel draw was much improved and the engine powered through turns better.

We flew the OS 28 on our FrankenSpad with the Q500 (no taper, rectangular planform, 500 sq in/50" span) wing, The first couple of turns were awesome, then it would start to snap out. Hard to tell for sure, as it was VERY turbulent air and it was hard to tell what was a snap, and what was turbulence! But the trend was that the plane would turn tight, but then lose turning ability after two turns. The only way to get it to fly SUSTAINED turns was to open up the turning radius by reducing elev. throw. Still turned pretty tight, though.

We broke another 10x3 APC. One flight, one prop. I talked to Don Veres who flew some tests yesterday, he broke both his 10X3 APCs. We have yet to break a 10x4 MA in the same period of testing. This is frustrating and we are not pleased with this APC prop. Yes, it performs well, better than the MA. But this is a performance-limited class, why burden ourselves with a more-fragile prop. Let's saddle everyone equally and get it over with. Landing breakage is frustrating enough, but envision the all-too-frequent situation where an engine has died during a heat and you need to land and re-launch. Such landings are usually plops, not greasers- now you're gonna have more broken props, which means you'll have to change the prop before relaunching. Frustrating. This testing is bringing back memories of when I used APC for 2610 and B, now I remember why I changed. Loved the performance, hated the breakage.

Say it with me now: 10x4MA! 10x4MA! 10x4MA! 10x4MA! 10x4MA!

Scott Gilkey
Jimbo
Posts: 1082
Joined: Sat Apr 07, 2001 11:28 pm
Location: USA

Post by Jimbo »

I fly APC props only, on all my combat planes and very seldom break props. Are you setting your props to be horizontal at the beginning of the compression stroke ? Are you having to land on rough ground? Are you landing hot? If so, try flaring off more speed before you touch. I understand that they do break a little easier but it shouldn't be excessive.
I have some 10x4 MA props, so if I get to fly this weekend we will give them a try.

Limited-B
Try it,you'll like it !
RHorton
Posts: 46
Joined: Tue Jun 03, 2003 8:01 pm
Location: USA

Post by RHorton »

Guys several years back I did some testing with the 10x3 apc and came up with the same results, And like scott I found breakages was more with the apc rather than with the Master Airscrew.

On another front last weekend at Shelly ID the second place finisher was flying a stock Irvin with a 9x4 MA. He was slower than the piped planes but he had a great time and didn't lose a plane. I am not sure we need prop restriction as the stock muffler goes a long way to limit rpm. I would suggest getting data on the full range of props we could use from a 8" to the 10 " diamenter and all the different pitches. Then can someone rig an engine with a stock muffler turning a 10x3APC to make it turn over 16,500 rpm. We have to look at what combat fliers do and that is they[:)] look for and they almost always find a way around a rule that isn't set in stone.

And keep in mind that the CD has to be able to enforce the rule and still hold the event.
User avatar
lightning
Posts: 1444
Joined: Sun Jan 19, 2003 10:53 pm
Location: USA

Post by lightning »

I'm like all of you guys who worry about breaking APC props - I've been through a few. Soooo I went and bought a couple of MA 10x4s. The plane flew OK, slighly less grunt than the APC but acceptable.
BUT, first landing, prop feathered horizontal - <b>BROKE IT!</b>[:0][:0][:0]
So now I don't know what to say as I did NOT break the APC when I tried it on the same plane a couple of days ago![?][?][?]
OK OK the MAs are cheaper[:D][:D]

Keith J (member OGC)
Radio Control Club of Detroit
RCCA #622
BigCountry
Posts: 479
Joined: Fri Sep 14, 2001 12:14 am

Post by BigCountry »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Then can someone rig an engine with a stock muffler turning a 10x3APC to make it turn over 16,500 rpm<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Ron, not sure where that rpm number came from but ours is 15,500 RPM's which my stock OE 25fx's will bust all day long on an APC 9x4. If you'd like to do some of that testing and report back to us that'd be great. Then it'll be up to you to change the minds of those who are trying the Limited B idea. Right now we've held two demos, three after this weekend under the initial draft of the rules and the only prop issue that has arose is the breakage issue between MA and APC. I think most guys here are convinced that the 10" prop is the way to go now whether or not it ends up being a 10x3 APC or a 10x4 MA remains to be seen but I welcome your input and if your stance makes enough sense and is supported by enough people then that could end up being what is done...

By the way will you be holding a Limited B demo at your event coming up? I hope ya'll will consider giving one a try...

Image
sgilkey
Posts: 2351
Joined: Mon Mar 19, 2001 8:26 am

Post by sgilkey »

If the only thing everyone will agree to is getting rid of tuned mufflers, but NO PROP RESTRICTION, I would still like it as a step in the right direction. HOWEVER, I really think we also need to go to 10" props. A 9x4 on an engine with a stock muffler can still make a plane really scoot. you're probably gonna drop at least 2, maybe 3k rpm, which is going to be a significant drop in speed.

Keith, sorry to hear you broke your MA prop, if you need landing lessons we can give you some at Saturday's meet! Just after i CUT YOUR A@@. just kidding. We break MAs too, but at a tenth the frequency of APCs.

Scott Gilkey
Jimbo
Posts: 1082
Joined: Sat Apr 07, 2001 11:28 pm
Location: USA

Post by Jimbo »

I'm at a complete loss for words here. Combat planes are capable of extremely SLOW landings if you flare off well and don't just flop it on the ground. We don't have a great place to land here and we are not having that problem. Maybe it's because Travis and I started flying combat with the original(fagile)Raptors so we had to learn how to land light and softly. Maybe if you keep in mind that the prop is easier to break you can stop the problem or bring the frequency way down.

Limited-B
Try it,you'll like it !
Grun-Herz-Geschwader
Posts: 213
Joined: Fri Feb 15, 2002 8:41 am
Location: Village Mills
Contact:

Post by Grun-Herz-Geschwader »

Here you go Jimbo you wanted to see the Slasher.
Image
Same thing again today 4 flights 14400 to 14800.
Oh yeah look at that prop APC, three landings today with the engine still running, don't know why it hasn't broken yet just lucky I guess?[;)]

Ich bin der vorbote des todes!
User avatar
lightning
Posts: 1444
Joined: Sun Jan 19, 2003 10:53 pm
Location: USA

Post by lightning »

Jimbo, plane was going slow and the tail touched first.
Motor was stopped and the prop was horizontal [?][?][?]
Go figure [:0][:0][:0]

Keith J (member OGC)
Radio Control Club of Detroit
RCCA #622
Jimbo
Posts: 1082
Joined: Sat Apr 07, 2001 11:28 pm
Location: USA

Post by Jimbo »

lightning what kind of plane do you use? Is there something simple you can put under the nose to keep it up a little?

Limited-B
Try it,you'll like it !
Jimbo
Posts: 1082
Joined: Sat Apr 07, 2001 11:28 pm
Location: USA

Post by Jimbo »

Good looking plane Charles. Bring it next weekend and I'll ugly it up for you[:p][B)]

Limited-B
Try it,you'll like it !
User avatar
boiler
Posts: 3336
Joined: Wed Jan 01, 2003 8:16 pm
Location: Ohio
Contact:

Post by boiler »

Today at the Detroit meet, we flew two heats with 11 pilots of demo limited B. Scott Gilkey collected props used, muffler condition, fuels used, and rpm. I used a fx unmodified muffler and Rich's Brew 15% with a 10-3 APC. I tached at 14100 tops and felt that I flew as well as planes taching 15300. It was a barrel of fun but mid-airs have more energy to dissapate than SSC. Less than Open B as would be expected. It could have been borrowed stuff that kept our distance from each other, but mid-airs were few for the number in the air. Of course yours truly was in the nastiest one.

Bob Loescher
Lima Ohio
User avatar
lightning
Posts: 1444
Joined: Sun Jan 19, 2003 10:53 pm
Location: USA

Post by lightning »

Yeah Bob, while looking for my engine that you smashed off the SPAD our rookie was flying, we found your fuel tank - still 2/3 full[:D][:D]

Keith J (member OGC)
Radio Control Club of Detroit
RCCA #622
Post Reply

Return to “Proposed Provisional Classes”