Strykaas

Hi there,

A friend of mine is using the following setup :

- Whiplash Extreme
- OS 50 SX hardly broken in
- 15% nitro fuel
- Tower Muffler

Which prop would you advocate for best speed ?
He has used a 9x8 prop, but he has been disappointed.


Thanks for your advice.

Strykaas.

C roundy

Strykaas First off, it would help me to help you if I knew what he's able to tach on that prop after he's broken the 50SX in; (its a ringed engine, and it will get screwed up if he leans it toward peak RPM to soon. Secondly, it would help to know how much his "Extreme" version Whiplash weighs ready to fly.
Having said that, with what you have stated in your post to start with, I can tell you a few things regarding "his" combo.
1)The 50SX is not a high revver, and a 9x8" prop is a good break in prop and starting point speed prop for the engine.
2)He will positively do better out of a dive with a 9x9' prop. BUT he will only average higher speeds if there is less than about 1300 to 1400 RPM drop static when stepping up that 1 inch of pitch; whatever he ends up taching on the original prop after he's got it broke in, and depending on how tight of a course he flys.
3)If his "extreme is about 3.5 pounds or less RTF, than he May be able to get decent enough traction to hook up effectively on the APC 8.75X9.0NN, or even the 8.75X9.5NN pylon props for slightly higher terminal velocity...

Regardless, if he wants ANY certain motor/pipe/prop combo to reeaalllly go fast he will need a lighter airframe than any Whiplash I've ever seen, and I've owned and sold 4 of them. They kept promising the next one would be lighter!...

Best Regards, Chuck Roundy

ChuckAuger

My Feedback: (12)

Aw come on, Chuck! You just didn't have a big enough engine! (Ducks, runs for cover, )

Strykaas

C roundy,

A big THANK YOU for your highly detailed answer. I was not hoping for so many clues...
As you mention, and as I pointed it out to him, leaning the engine from the very first flight could be detrimental to his RINGED engine...
Anyway, I will tell him to carry on with the 9x8 !
I remember he told me he uses the heavier version of the Whiplash, so it may not be an 'Extreme' but an 'X' version, sorry for the confusion.
I will give you the take off weight as soon as I know it.

Something was fun, SalmonBug was nearby (playing the fool) with his Whiplash/46FX and he was actually faster than my mate's same airframe + 50sx [sm=devious.gif]...
Yes, the 50SX was not broken in, but may my mate expect a big performance increase after break in ? My understanding about ringed engines is that they gain compression over the break in period, thus higher RPMs...

Again, thank you.

I'll keep you posted about how things turn out.

Strykaas.

SALMONBUG

My Feedback: (1)

playing the fool [:-]

by the way, your fella's whiplash is flying the same speed than my 46fx one from what I have seen
. my 46fx is fully broken in and has a long history of fast reliable runs.
your fella's 50SX is brand new, once your fella's 50SX will be broken in, he should fly faster than me. we will tach the 50SX and weight your fella's plane.

fly fast is also a way of flying, involving particular dives and throttle management. Your fella will learn that soon also and will fly like a rocket soon !!!

Strykaas

I've gathered some information :

- take off weight : 1900 grams = 4.18 lbs
- static peak RMP (9x8) = 16200

What do you think ?

Crazy4Flight

My Feedback: (540)

I have a 50SX in a tequila sunrise the OS has never proven itself for power,

once you have mastered flying the whiplash...Buy a Dubb Jett 50 FIRE & tuned pipe.

you will not be dissapointed

Strykaas

Well,

No doubt a Jett .50 will make it (I told him so) but... he only has a 50sx for the time being and want to get the most out of it !

Any further advice ?

ChuckAuger

My Feedback: (12)

I think that's about all the OS 50 will give. I don't know what else you are looking for, if he's not running a full pipe, he's not getting all he can from the engine. A pipe is a great performance boost for not much $$, but that OS 50 ain't gonna do much even with a pipe. There is no magic bullet, except $$.

SALMONBUG

My Feedback: (1)

thrue,........

i'll give the guy Dub's email

C roundy

Yeeaah, Yeuupp,... I gotta admit I admire that credo immensely ChuckAuger, POWER IS YOUR FRIEND period... But in my old age at 41 yrs. I have come to value the flip side of the same coin with at least as much ferocity, WEIGHT IS YOUR ENEMY period... I have followed your exploits with the extreme horsepower/high RPM, big bore engined Whiplashes with singular fascination and highest respect; Boldly going where no man has gone before! When you know damn well that no matter how well you prepare the airplane, it may fail catastrophically at the speeds and forces that you subject it to. By God in my book thats the stuff legends are made of!!![sm=sunsmiley.gif]. I also bow to the "Good Ol' Boy" tenacity to take the closest engine on the market to what you envision in your minds eye as the ultimate attainable performance for an application, and then have the audacity to teach yourself through experimentation how to wake that motor all the way up for your target RPM range on your targeted range of props.
Dang I just read what I just wrote, and it sounds kind of sappy; But I let it stand[8D].
Anyway, as for myself I have been going "the other way with it" for a couple of reasons..., 1)like I mentioned, for me lowest possible weight/wing loading possible for a given speed range and gee range takes precedence over the outright horsepower approach because in my own limited but interesting experiences, I find that I have waay more success attaining higher terminal velocities by concentrating on light weight. At the same time I wholeheartedly admit that Have not put the effort/money/and time that you have into the big bore motors... (who else has!). 2)As for myself, and speaking for myself alone, once I spent time with a few lightly loaded, stiff, and straight, but Nasty fast airplanes, I became spoiled by their handling characteristics...no scratch that, downright addicted is closer to the mark!
Because of this doctrine, I have been able to approach perfection with a style of flying that I have never seen anywhere period. What really gets me off is the ability to take a model flying at fairly ridiculous speed, and out do myself in small steady increments to fly a tighter, and tighter, and tighter, precise pattern aerobatic course. I mean Right in front of me , up close and personal, to the point that when I slam monster rate elevon pullouts I feel the concussion of what the model has done to the innocent air molecules...[sm=cool.gif]
This Kind of flying, has me doing more maneuvers per second, minute, and flight, than anything else I've seen bar none. And thats what I'm really into the delta's for, Reflex Tune-up Baby!!!
P.S. I would dearly love to see one of your Rossi engines run on a purpose built ultralight/small airframe ( my best mentor pushes me to biuld my engines into the smallest lightest airframes that I dare, and damn him to !@#$%^ I'm grateful,... he has caused me to out do myself Bigtime so far).
P.P.S. I also wish like heck that I was some rich globetrotting playboy so I could afford to just come on down and fly with you; I have no doubt that you are one helluva pilot, and that I would learn alot from you[8D].
Best Regards, Chuck Roundy

C roundy

Sorry for taking a while to reply to the actual poster of this thread Strykaas, I got a little bit distracted deciding what I really wanted to say in response to another one or two of the other brothers in arms who have made replies; But simply put, ChuckAuger has already nailed it, your friend is not going to get much more out of an O.S. 50-SX... the "Tower Muffler" is a not to shabby 1/4 wave tuned pipe (for its price)...the Jettstream "muffler", and/or the Performance Specialties Ultrathrust "muffler" will realize slight
increases for your friend. And A full wave tuned pipe may offer about 5-8% increase over all the other options with this particular engine. Thats about it. In other words, everything else remaining equal, there is nothing that will let him carry another inch of pitch effectively for application on this airframe.

Best Regards, C.R.
.

ChuckAuger

My Feedback: (12)

Well stay tuned. The Whiplash was just an engine test bed...fast planes don't have draggy bits hanging out.

bob27s

My Feedback: (19)

The 50 is a pretty good engine. The sleeve is pipe timed, and will gain a bit from a good exhaust system.

You may want to consider trying a Jett-stream muffler instead of the tower muffler.

The tower muffler has limited boost, peaking at about 16,500 rpm.

The standard 50 size jettstream is design for the 16000 rpm to 18000 rpm range.

Dub can provide you with the Super Sport muffler, which is tuned for the 17 to 19,000 rpm range. You should be able to push the 9x8 into the 17K rpm range. Then the muffler will let the engine unload in the air.

Bob

SALMONBUG

My Feedback: (1)

ok, because >I have a jett engine on it's way to houston for servicing, I will ask dub to join it a super sport mufler for our fella

this will save some shipping money