Erik R

My Feedback: (32)

Razor,
My starfire goes wot 150-170 mph staright and level.The P-51 is pushing 130 IMO.Also, mine is a 60 sized plane,not 40 sized.I agree that a 108 in a 40 sized plane would be silly,but offered the info to suggest that the modeltech design can be tweaked to move along.I think the Jett 90,Rossi 60, or the Tower 75 would all do his plane justice.Also,I noticed the Webra speed 61 is now available again,and I had very good luck with that engine powering a Top Flite P-51 (old style,not gold edition) 20 years ago.In any case,good luck!
Erik

Razor-RCU

My Feedback: (50)

MGlavin- Will do, turns out my bro was using a 16x8 on the YS-120... Told him tonight to try a 14x12 (thanks for the tip-)

All the numbers look good to me- If thats true, the 4 strokers sure sound perfect in warbirds!

Erik- My bad, did not realize that was a 60 sized bird :stupid: -
I always wanted to try a 1.08 but...

The Webra speed 61 would be like the Rossi and YS's I mentioned- Sounds good!

Get an OS-91VRDF and finish this thread!

Keep us posted,
james

Flyboy Dave

My Feedback: (21)

Mr Spears....I did understand the question, and I do know
the engines in question, my flyin' Bud has been running
the Jett .90 for a couple years now....

....what you don't know, Mr. Spears is is the conditions
inside my ball park....I see your in Fla., at or near sea level....probably around 85 degrees....and relative humidity around 80 percent. (I'm guessing)....

....basically, air so thick you can cut it with a knife.

Out here in the High desert of So. Cal., the conditions
are quite different. If you look at the handy performance
chart for density atlitude....at 3500 feet, at 105 degrees,
and humidity at 5 or 10 percent....you will notice the the
lines converge right at the "squat-diddley mark".

As an example....the Jett .90 with the recommended 11-8
prop turns at a non-impressive 14.5 K, on 15%....at what
did you say....6HP ? At the same time, my little OS 60 FSR
with a turbo muffler on 15%, and an 11-8.....at a "rated"
1.9 HP turns 14K. (so much for the the HP ratings)

Therefore, I will place my "bettin' chip" on the supercharged
1.10 YS with the high nitro, and the high pitched prop in
the WM Dago Red to smoke the Jett powered apparatous.

Your mileage may vary....

Dave.

ewspears

My Feedback: (12)

mglavin
Your 2 stroke vs. 4 stroke argument, while correct with respect to the Warbird Racing Rules, is incorrect from an engineering standpoint and also incorrect from the original question/request.

"How could he make the 40 size P51 faster without respect to the racing rulebook"

I've got no disagreement with the numbers you stated on the YS 4 strokes but Quoting Jett numbers is a little more difficult because the port timing and compression, on all but Dub's most popular models, varies greatly. Basically Dub will build them to fit your application. The numbers you stated for a 12X6 Prop are I'm sure conservative & correct; BUT They were numbers influenced by your request and Warbird Racing Rules.

You certainly don't need a 12" dia prop on a 40 size plane if all you want to do is go fast. My Jett 90 will turn a 10X8 uncut APC at just over 18K on the ground and will unload considerably in the air depending on planes speed. Should pull about 20K with a 40 size P51.

The Jett 90 setup above wouldn't meet the rules, wouldn't look or sound cool, and wouldn't have strong climb and acceleration qualities; BUT
It would be a whole lot faster than any YS 4 stroke (including a DZ if you could stuff one in)

ewspears

My Feedback: (12)

Flyboy Dave,

There's one thing I can agree with you on: Horsepower Ratings, as used by the model engine community, are worthless.
HOWEVER:
Horsepower as used by the Gas Turbine Engine Folks is the most important criteria when comparing engines. The differences are:
1) The horsepower is stated on an ISO Standard Day (59 Degrees F, Sea Level, 29.92" Barometer)
2) A horsepower correction algorythem or chart is provided to correct horsepower to other atmospheric conditions.
3) The horsepower is stated at the RPM producing max horsepower.

The original post here was to make a OS 61 powered Modeltech 40 SIZE P51 SCREAM, SCREAM, SCREAM!

You and MGlavin have posted Jett numbers that reflect Warbird Rules, Larger than subject airplanes resulting in larger than neccessory propeller which results in an RPM far below a "Full House" Jett 90's Max power point.
Plus the numbers you're speaking of are probably without a full length tuned pipe.

"Therefore, I will place my "bettin' chip" on the supercharged
1.10 YS "
HOW BIG ($?) of BETTIN CHIP are you thinking of?? I was planning on putting my Jett 90 in a Patriot but if your "bettin' chip" is big enough and you can come up with a Modeltech 40 size P51 with a YS 110 We should do it!

Rudeboy

At what rpm does a Jett .90 put out 6hp...?

Flyboy Dave

My Feedback: (21)

About 50,000....

Razor-RCU

My Feedback: (50)

I want to change my answer to a GMS-47, followed closely by a Cox .049 Black Widow!

Seriously- for the absolute best performance one would need to SOMEHOW get an OS-91VRDF on there-

"I love these threads"

ewspears

My Feedback: (12)

The 6SHP vs. under 4shp was comparing stated numbers which I've already acknowledged is not worth two dead flies. I don't have a torque measuring test stand so I'm not sure of actual numbers, probably about 4.5 shp at 22K for the jett.
Forget about the shp numbers, lets get back to a wager!

Flyboy Dave has said he would bet on a YZ FZ110 powered Modeltech 40 size P51 against the same plane with a Jett FIRE 90.
MGlavin also seems to think the YS would have the edge.

Flyboy Dave, Why don't you round up all the people that believe the same as you to put up some money, I'll do the same.
We agree on a neutral testor with speed measuring capabilities, maybe in Texas. We both submit stock P51's (except for the engine installation) Fastest in level flight takes all the marbles.
Since I'll have to purchase the plane anyway I'll open it up to any reasonably sleek 40 size plane. Probably save time and money if we just used 40 size Ugly Sticks.

THIS COULD BE FUN!

Steven H

Very interesting thread so far. I hate to be a pest, but what ype of air frame problems will I run into, if any?

I just ordred the tower .75, I got a lot on my plate, so it will be a week or two before I get her in the air. But I will let eveyone know how it goes. I think I will try a 10/8 apc to start with. what kind of rpm's do you think I'll get? any comments or suggestions on prop selection?
thanks

Steve H

ewspears

My Feedback: (12)

Steve,
My YS 60's, FR's or FS's, will turn a stock APC 10X8 16750 on 15% fuel at 90 degrees at sea level. The port timing on them is set up to be ideal in the 15 - 16K range.

I've not been inside a TH 75 but I suspect it is timed for lower RPM but I imagine the shp is close to my YS 60's

What this means is; I'd break it in first then I would use the 10" APC that would peak at about 15.5K Depending on how strong it is you might end up with a 10X10.

All this assumes a full length tuned pipe

Rudeboy

This is the most sensible thing I've read so far in this thread... put your money where your mouth is guys...

SSAN

Dave,

With all do respect, I don't believe you have any experience with Warbird Racing in general. Anybody that race the Gold Class know that in order for the 4 stroke to be competitive with the 2 stroke, it needed to be much more in displacement than the 2 stroke and run much higher Nitro. To compare a YS .91 to a Jett .90 2 stroke is like comparing NASCAR to Formula 1. It's insane to say the least.

Here's an inside scoop...

The reasons the 4 strokers are competitive is because the rules allow it to be. It seem as though the Warbird Racing organization wanted to get rid of all the 2 stroke guys because of the noises and speed these guys are going (and they did a good job of it) to give the 4 stroker a chance. The size of the plane and wing area were more of a factor which give the 4 stroker guys the advantage. If the rules were equal, the 4 stroker would have no chances what so ever (except in static scale judging).

FYI... In the early 90's of Warbird racing scene, the .40 size full piped 2 stroke would run circle around a YS .91 (including leaving many YS .120's in the dust) that were using 60% Nitro (credit to Mike Del Ponte) so to compare a Jett .90 to YS .91 is unheard of. But than again... your mileage may vary.

mglavin

My Feedback: (31)

As was mentioned later by the thread originator, he was speaking of the WM Mustang. Same .46 Mustang I am speaking of and comparing my findings to. I have seen several of these setup with hot .61-75 two strokes on full length pipes. They didn't do it then and won't now. These models are LARGE by comparison to say a Dynaflite/Pauls Flying Stuff/HOB or the like.40 size Mustangs. The YS-91's eat those screaming demons for lunch in these models. You just have to see it to believe, honestly.

Presently we have several YS powered planes that are untouchable at our field. There is some hot dogs that come up from Arizona and really burn holes in the sky with YS's, it's truly amazing to see! Up to 85% nitro is consumed when need be. The new 110s are very impressive on 65%, were seening 12,500 on the ground with the 12/13 APC's

I'll give the Jett a new mount soon and see what happens, small props and all. BUT I have very little faith in this combination in these Mustangs. But I can do it without buying anything and I'm up for the schooling.

The 20K numbers are impressive on the Jett 90. Static thrust is nearly equal with the 10/8 @18K and the 13/12 at 10.5K. Theoretecally the 10/8 should be faster. I just haven't seen it happen at the field. Running the 110's with the 12/13N at 12,500 and the mph numbers favor the YS by over 20mph. Agian its math not reality, but the field seems to validate it.

ewspears

My Feedback: (12)

SSAN,
You're absolutely "Right on the Money" in my opinion!

MGLAVIN,
You're wrong about the airplane in original post. It wasn't a World Models, it was a The Modeltech P-51D Mustang 40 Size. This has a 57" wingspan and comes with retracts.
BUT:
To make it easy and cheaper I've opened the wager up to any reasonably sleek 40 size plane that is readilly accessable. I've even suggested 40 size ugly sticks!

If you really believe what you're stating hear on RCU, This is a golden opportunity for you to make some money and have fun doing it. I can already tell that supporters of my position are going to be able to "call" your bet!

mglavin

My Feedback: (31)

ewspears

Your wrong. Yes the original post mentioned Modeltech, as I mentioned Steven H recanted in post #13. see below.

See Stevens post #13,

Oh yeah, this is a World Models, not a ModelTech like I said in the original post. I'm getting to the age where I forget anything that is not written down. (Just turned 40)

Also note Stevens post #7,

Thanks a ton for the idea's. I would like to stay away from large tuned pipes because of the appearance. I have seen the Jett pipes they look good to me. Would the Jett 50 make that big of a difference? Or should I just go with the Jett 90 and get it over with?

-----------------------------------------------------------------------------

Suggesting any other plane is moot, we're discussing this specific model. Changing the model or specific airframe will certainly effect the engine combinations and performance realized from the engine combinations quoted. My experiences are just that real world field experience, not conjecture, not speculation and nothing more or less... And these performance numbers can be validated by several modelers over the last several years.

The World Models Mustang is reasonably cheap and readily available, this is the primary reason we use them. Retracts are included and they are available in several different color schemes.

I really don't feel the need to bet, I commented based on what I know to be true. I did'nt try a Jett .90, it was a .75. I doubt there will be a substantial difference. I wasn't running a full length tuned pipe, but Jetts 1/4 wave tuned muffler and several different props were tried. The 12/8 I mentioned is the prop Dubb quotes numbers on from Jetts's website. Additionally the engine was using a Jett RC carb verses an air valve, this required by our local rules, the engine must actually idle for 10 seconds.

You are correct in that I made several comments based on what is required of engine displacements and wing areas for our Warbird Racing venue, the RC carb is also along these lines. Any prop and fuel can be utilized.

ewspears

My Feedback: (12)

MGLAVIN,

This discussion about whether it's a Modeltech 57" W.S. P51 or a World Models 57.5" W.S. P51 is just extraneous smoke!

The offer of Wager still stands with the World Models 57.5" W.S. P51!!!!!!

Believing as you do; Why would you miss the chance at some $ and having fun at the same time???

mglavin

My Feedback: (31)

ew

There is a potential problem, how can this duel happen? I live in Sacramento and you live in Florida.

Smoke it is not, like I said been here done this. The Jett didn't get it! But as I mentioned I'll try it again. It's possible I missed something I'm willing to admit it. But like I said I have seen several other similar combos with 60-75 fire breathing fully piped screaming two strokes on this model. There's been a huge crossection of effort over the years.

Your taking this way to spuriously, IMO.

ewspears

My Feedback: (12)

MGLAVIN
We're not talking about a pylon race. What I'm suggesting is just ship the models to a neutral person of demonstrated ability and let him clock both models in level flight and declare a winner. I've already suggested to Chuck Auger that since he is "sitting on the fence", has the demonstrated ability, and is located about halfway between us, he should consider being the tester.
If we get the wager large enough the kit and shipping costs would be inconsequential.

mglavin

My Feedback: (31)

EW

All of a sudden were NOT talking about pylon racing? Says who? This has been the catalyst from my first posts and has continued through my latest post. Pylon racing will tell all, IMO. This seems to be the standard that all racing is based upon not to mention all the guys that like to fly the pattern balls to the wall.

Straight line speed contest? This is the first I have heard of this. Looking for a perceived advantage, eh? NOT! What's the matter someone enlighten you? Maybe we should do the straight line thing from altitude, straight down and see if we can shed some parts. Maybe then the Jett will unload the iddy biddy prop and have a chance.

Tell you what let's bag "clocking" the models and use my Stalker Pro radar gun. Maybe I should just ship it to Chuck as well. Or I could fly out to this neutral territory and we'll separate the men from the wannabe go fast boys with their toys that seem to know more about these models and YS Engines than those that own and race them. So lets forget shipping the models and just meet half way. I don't feel comfortable shipping my model to a complete stranger that may or may not know how to operate a YS Engine on Nitro. Not to mention piloting skill. What about the possibility of damage due to operator negligence and or error?

I'll bring two WM Mustang powered model's, one will have a YS-110 and the second will have the Sport Jett 90. Should even the playing field.

I have the actual hands on experience with this model and these engines. I know what needs to be modified and not. Were going to have to establish some standards. These standards should be based on the parameters expressed by the thread originator.

You've made it painfully clear that a wager is in order and nothing else will suffice. So how much is going to make it worth your while, EW? Were talking DOLLARS right? It's going to have to be "lucrative" enough to cover my traveling expenses at the very least and then some additional funds for educating you!

mglavin

My Feedback: (31)

Reading through the posts to refresh my memory I noted a few things that I would have commented on had I absorbed the info a little slower, I suspect.

PURE speculation, with no actual experience with the YS-110 and or FUEL...

Please note: A Jett 90 is referenced several times, NOT a Jett FIRE 95.

ewspears

My Feedback: (12)

MGlavin,

Talk about spinning things!!!!

1) Pylon Racing??? - No where in my posts have I mentioned Pylon Racing Contest. I've even gone out of my way to explain the contest I had in mind wouldn't be encumbred by any Pylon Racing Rules.
This very Forum " Extreme Speed Prop Planes" is about DD's, Whip's, Magnum's, Patriot's, F20's, and Homedesigns. Many times props are so small and acceleration so low that normal or hand launch takeoffs are impossible and dollies must be used. When's the last time you heard someone in this forum talk about "What prop would give my Dust better acceleration off the pylon" - NOT!

RCU covers Pylon Racing in other Forums. BESIDES,

I wouldn't be so stupid as to make a wager with a Pylon Racer about about a Pylon Contest where he was wagering with actual knowledge of outcome and I was calculating results. Also as Razor pointed out the pilots skill level has a considerable effect on outcome.

THIS POST HAS BEEN ABOUT STRAIGHT LINE SPEED FROM THE GET_GO

2)I have not tried to change the engine in any of my posts. To the best of my knowledge I've never mentioned Jett 95. I only own one Jett in that size range. It is a Jett FIRE BSE 90. For clarification, I've hopefully attached a photo of the exact engine I'm speaking of.

While I'd love to see a demonstration of a couple of your Pylon Racers and would undoubtedly learn a lot about present day Warbird Pylon Equipment I don't think I would want to pay your expenses for the experience. My whole idea was to place both engines in question on identical 40 size not too draggy airframes and wager on which was faster in a straight line.

This whole thing comes down to some statements you've made that, while may be true within Warbird Pylon Rules & Practices, I believe are not true from the simple standpoint of; Will a "Full House" Jett 90 make more SHP than a "Full House" YS110.
The power will equate to speed unless you have such a draggy airframe that the reqd. prop diameter is operates below the Max Power RPM for the Jett.
You say I have "no actual experience with the YS-110 and or FUEL... : That's correct with respect to the YS110 but I've got experience with YS 140DZ on 30% Heli Fuel and 2strokes up to 70% nitro.

Further; I'm not in love with the Jett! I have Rossi 90's which could also be put on a "not too draggy" 40 size airframe and also be a WHOLE LOT FASTER THAN ANY YS 110 on the same airframe, straight line, level flight.

This simple premise is what I am willing to wager on. I'm sorry if I sounded antagonistic. I was just trying to boil down the disagreement to the simplest terms. To accomodate you, I even agreed to the 40 size Mustang of your choice. Were I trying to spin it my way I would have suggested a Patriot as the testbed since that is what the Jett was going into anyway.

FlooredCOBRA

this Ford vs Chevy debate is getting deep....

Steven H

Hate to get off topic, but I wanted to ask a few questions about how to make my P51 scream!

Took her up the other day, Went up 300' or so, rolled inverted and dived for the field. Just starting to pull up past 45 degrees and I heard serious flutter. Pulled back on throttle and stick. seemed ok except roll was out of trim. Landed with out a problem. Plane seemed o.k.. It has two aileron servos, but they are mounted inside of plane using the stock torque rods. I know this problem will get much worse when I get the tower .75 installed. I'm looking for some ideas to rectify flutter.

I'm considering sheeting over the inside half of each aleron. Using mini servos mounted in outboard portion of wing with very short linkage. If I do this, what is the smallest servo I can get away with?

Steve

r-c-guy

My Feedback: (37)

Hi,
I have a df os .65 with a full pipe on mine. 11x7 or 11x8 shaved produces in the mid 20k's in the air and over 180 mph.
speed isfun!
randy