Big block Whiplash - heartache or happiness?
 

Hi folks,

I am looking for some input from folks with some Whiplash experience - or anything close enough and heavy enough if you get my drift. I've been staring vacantly at this aircraft for a while, and mulling over stupid ideas, but apparently it is time to get off my dead posterior and get cracking on this thing now - if the peer pressure and ridicule to which I have been subject at the hands of some merciless fellow RCU members is any indication. In other words, it has been declared that this is the next project.

So.. the stupid idea of the day is to fit this with an OPS Speed .65, that's a RIRE .60 block size engine for reference, pipe and all that, 10 oz or so of fuel capacity (tandem bladderless tanks I think), mondo servos and linkage as required, and.. maybe.. cowl in the engine and pipe.

According to the weigh-in pictured here, which used a combination of the real bits and some parts that weigh the right amount, it looks like it will come in about 4-3/4 pounds. I tried to be generous with the weighting here, hoping to come out a touch less in the end but it won't be much lower.

The $64 question: I know that, if & when flying this thing will flat out haul and is a realistic 200 club candidate. I'm not scared to pilot it, I've been flying RC 34 years or something and flown all sorts of cantankerous crap. That part is my problem, but it is the aircraft's manners at this weight that troubles me. I haven't dealt with a wing loading this high on a delta before, so don't have a good feel for how badly gravity will be trying to ruin my life.

Plus, I just wanted to try doing a poll for fun. It will be well and truly out of my system after this one, I promise.

Thanks in advance for any useful or interesting tidbits you may have to offer.

MJD

RE: Big block Whiplash - heartache or happiness?
 

I'ts the wild launch, not the landing you need to worry about and that APC prop is bit too close to you if it lets go. A 5 cell AA pack the minimum, better to use a 5 cell 2/3 A size pack, they have much more current dump and a bit lighter but less capacity. I get at least 10 violent flights powering HS-7955TGs on my DD before needing a charge. Don't skimp on servos, that skin hinge is stiff plus you got a ton of power there.

RE: Big block Whiplash - heartache or happiness?
 

Prop:
Well, these stock APC props (including all versions of the pylon D1 series) become dangerous in combination with 10 to 15 cc ducted fan or speed engines- they're too weak structurally! [X(]

If the propeller does break during flight at full throttle, the engine mount can easily be ripped-out of the Whiplash airframe. [sm=sad_smile.gif]



For this particular WHIP-project, a well suited prop size would be something between 8.5x10, 9x9 or 9x10.

So a continuous strand carbon fiber copy of the
[ul][*] APC 9x9[*] APC 9x10[*] APC 8.75x9,25W (LP088094)[*] APC 8.8x9.75 (LP089098)
[/ul]
would be the best solution for reaching or exceeding the 200 mph speed target safely.

Alternatively – which has already been suggested in other OPS related threads – you could simply use a firm wood prop such like ZINGER 11x10 (#513), shortened to 8.5” of diameter.




pipe length:
The pipe length can be set at 12” between glow plug and the middle of the belly of a twin-cone pipe (or the location of the deflector) and can be shortened appropriately down to about 10.7” depending on prop size and nitro percentage. In one of the OPS threads the procedure to apply a trimmed-down test prop (during static ground tests) for finding the optimum in-flight pipe length is explained...

The static rpm should reach at least 20000.




tank:
A bubble-tank is mandatory – the tank volume should not be smaller than 300 ml (10oz) in case of the OPS .65 RIRE.

Besides the bubble tanks made by JETT there are also several bigger bubble tanks by TETTRA:






cowl:
As for making a cowl for engine and pipe, that is not necessary in this delta-case.

With your setup 200 mph will be achievable without a cowl. However delta type airframes in combination with propeller propulsion usually will prohibit achieving considerably higher speed – independent of any cowl.

For a flying-wing type speed airframe (ME-163 -ish etc) - coming with much higher aspect ratio – aerodynamic refinements are very welcome and promising to gain more top speed.

A conventional type speed airframe for instance can be refined quite effectively by adding fairings and an engine/pipe cowl to gain up to 20% of top speed potentially.





Wing load:
The take-off weight of your Whiplash (about 2.5 kg wet) will be non-critical. Some of the German flying wing type speed planes powered by the OPS .60 VAE engine come with higher wing loads...

To reduce abrupt torque roll tendencies during take-off (induced by the small delta wing span in combination with a lot of static thrust by the "squared" prop size) you may hand-launch at only 75% of throttle (i.e. “off-pipe”) for instance.

RE: Big block Whiplash - heartache or happiness?
 

GO FOR IT!!! With any luck you can get the CG close to spec, if not give yourself a lot of up elevator on high rate for landing...nose heavy it will glide like a brick.

RE: Big block Whiplash - heartache or happiness?
 

The good thing is the deltas have good size wing area. The bad is short span so torque on takeoff is sometimes an issue... Do it, film it, have fun.

RE: Big block Whiplash - heartache or happiness?
 

Go for it! Please pass the POPCORN.:D

Looks like FF takes his own advice.

RE: Big block Whiplash - heartache or happiness?
 

I-L-J always has good info and points. The 9" props have a small hub and with TIME even my YS 45 RE will throw a blade at the hub. My OS 46 DF will take the tips off any APC pylon so carbon was the answer for that. Some guys have gone with larger APC props for the larger hub size and cutting them down and reshaping, but that’s a lot of work and I won't endorse that idea.

Id go with the Zinger route, they come six to a package from the factory, so could make some 9, 8 3/4 and 8 1/2 " in diameter, a little hand clean up ,round the flat off leading edge and feather the trailing edge(a bit), on a Zinger helps anyway. Of course you will need to reshape/thin the tips after cutting down the diameter. Rub in some thin CA in to the thin areas to toughen up the wood when done shaping. Balance than final balance with the nitro proof spray paint that you use to seal the wood. Re-check balance when dry. Man that engine will rev up fast with a wood prop.

Crazy4Flight has a good point, I don't think you will get the CG right unless you add weight and I hate that. So, like he said land hot with high rates, it shouldn't be a problem unless something jumps in front of it.

By the way MJD, I like the red Jett carb on it. What's it from?

RE: Big block Whiplash - heartache or happiness?
 

It takes all the strength I've got in my left hand to hold a .40 powered DD for take off......I suggest strength training with regular steroid injections to be able to handle the OPS. My .40 sized DD weighs 3.5 pounds, and when it's time to land the glide is OK, but it definitely lands where it wants to. At closer to 5 pounds on the same size plane, you'll just have that much more plane to love. A launcher with just a little bit of forward assist would be nice. Don't trust helpers, keep them the F&*#@ away until the show is over!

RE: Big block Whiplash - heartache or happiness?
 

Tell us how you realy feel. LOL.

I don't use helpers either, unless I'm required to in a race.

RE: Big block Whiplash - heartache or happiness?
 

MJD:

Wow!!!!!! The guys sure gave you spot on great advice all the way through based on my limited experience with the DD. I do stgrongly second combatpig's advice to use a launcher. Tendency to torque roll is gonna be rough until you reach some speed and altitude. Go to www.yourzagi.com/launcher/ for a decent proven bungee pedal launcher and list of materials. Am building one for a couple of my off the path projects, a electric "Fun Jet" tested at 200+ and couple of home brew kit bashed Q-500 designs Jett 35 and Jett 60LX power along with a couple of modified "Fun Racers" deltas given to me by a couple of the club guys that got over their heads real quick. Scored some very nice air/spring micro retracts from Hobby City for $56.00, very well done, good for 3 pounds max. Just had to try one of the new EDF eurofighters and see if I can get it to hover? Doubt if my hopped up OPS will ever see the inside of a airplane. Just too heavy for my design likes and dislikes as compaired to a Jet 60LX or carbed Nelson something. Yesssssss, I know there is big power lurking in there, but more in the OS 91VRDF? A little easier to deal with, I think.

Supprised to see this old speed freek playing with electrics? Not enough power you think? Thats what I thought until a club pylon event last year. At around lap 5, was starting to lap most of the guys. In the corners of my eye there was a little shadow creaping up. In the last two laps, the thing forced me to work to tighten up in the turns to keep it behind. The thing turned out to be a electric F-27 wing with a hot motor flown by a out of towner who crashed his Jett 40 powered LR-1 in practice. Natrally the thing caused me to do some research. No doubt that I can go faster than you can right now. The real question is can I do it for 10 or so laps? Frankly am close right now using moderate cost batteries $65.00 VS the real good stuff at $256.00. In the future if you hear something running 30,000+++ behind you, look for a old man, or his ghost with the big grin on face!! ENJOY

RE: Big block Whiplash - heartache or happiness?
 

Roger.....always with dastardly [or substitute a B for the D] tricks to play on the unsuspecting :D.

I just got back from the barn and was looking over my .40 sized DD. It always looks BIG to me just sitting there. No way do the outer half of those wing panels produce more than a pound of lift at 20 mph, you don't need to be a rocket scientist to see that.
Now if MJD wasn't so lazy, he'd scratch out a 120% DD for his MONSTER MOTOR and do a little bit of R&D before committing so much faith into that plastic toilet seat cover with the fancy paint job!! :D.

Even the guys from central California should be able to see the infinite wisdom here?

RE: Big block Whiplash - heartache or happiness?
 

I see something, but I ain't sure what to call it.. ;) .

CP, looks to me like you is chuckin' rocks at that darn hornet's nest again. Confound it, how many times do I have to tell you, you gotta douse 'em in lighter fluid first.

To all, I must apologize profusely for not answering more quickly to the flood of info or, well, whatever it was (kidding!!!) that was waiting for me here this moring. In truth, I typed out a three paragraph reply of drivel around 10:30 or so this morning, then again had an IE lockup. This is getting chronic the past 3-4 days. I need a PC geek in a bad way.

Lots of good info and encouragement. ILJ as always thanks for the detail work you put into your posts!

Here is/was my genreal game plan and whare I am at on this and that:

- Already lined up someone who knows plenty about molding CF props for racing applications, and we're going to hook up sometime soon to talk about the dark arts. Thanks Ed!

- For break in and probably for first flights I will indeed be using Zinger 11-10's trimmed and shaped and balanced as needed. I am targeting inflight rpm of 22-23k.

- I had HS945's, but those were for use with a .50. Mightier sevos will be installed.

- The cowl/turtledeck is for maybe a bit of gain, but primarily for looks, fun, to be different, and I think there will be a little more leeway to locate small parts under a turtledeck/pipe tunnel/cowl, esp i am thinking the battery in the back forty.

- I fully intend to catapult launch!! No wussy hand drops, er, tosses for me anymore. I have a Blink-a-pult nearly done right now too for the same reason. Why screw around with small high pitched props and aspect ratios of 2:1..

Today was fun time - back the Nissan into my buddy's garage and did brakes/rotors all around. Wow, it stops now. It was cold and salt had welded a few things together. Thank goodness for acetylene and oxygen..

Cheers, keeling over asleep at the keyboard... just spent a gift certificate on a real nice dinner with me wife. Bloated, fat, full.

Oh yeah - thanks to all for the encouragement and war whoops! The project moves forward!

MJD

RE: Big block Whiplash - heartache or happiness?
 

MJD, I will fully stand behind your effort to make that thing fly. In fact, I'll be way behind it and surrounded with sandbags, too! :D
Today was auto mechanic day for me too. I've got a beater truck for hauling garbage that needs to be looked at every 5-10 years. The front brakes were locked up, it took heat, penetrating oil, sandpaper and a big hammer to loosen up. The rear axle had stopped leaking oil, so it was time to refill it too......gotta pull an axle to do that. Nice to have a rig that doesn't need to have the gas pedal floored to go 50 mph now.
Sounds like you've got a good plan of attack. I'll bet Ed has quite an interesting shop full of tricks....and a wealth of knowledge.

RE: Big block Whiplash - heartache or happiness?
 

That poor engine, destined to a life of sitting in an engine box and dreaming about flying.. [&o]. It must feel like an orphan. I'm adopting.. I would rub it with castor oil every day and read it stories and show it all the airplanes it could power and..

Last time I heard something running 30 grand behind me, it was my screaming wife chasing me around the house with a cordless Dremel with a carbide shaper bit. I told her it wasn't lipstick, it was red butyrate - I must have had a smear on my fingers and and scratched an itch on my neck and a few on my shoulders and..

MJD

RE: Big block Whiplash - heartache or happiness?
 

I always get emotional when I hear stories about thoroughbred engines held hostage in closets or just stared at in display cases....it's so cruel. [:o]

RE: Big block Whiplash - heartache or happiness?
 

Anything would be easier to deal with than we're gonna be, after being reminded about your OPS - the letters don't stand for On Permanent Standby!

I'd be happy to find out how easy your engine is to deal with.. the castor oil is already warming over a candle.

MJD

RE: Big block Whiplash - heartache or happiness?
 

I find myself in over my head in these forums, I will defer to the numerous posters who have more experience in mounting 60-sized case engines and flying them in Whiplash airframes.

RE: Big block Whiplash - heartache or happiness?
 

A 9x8 is a good training prop, but did you ever try to fly it or hand launch it with a speed prop?

RE: Big block Whiplash - heartache or happiness?
 

Never mind, not worth it.

RE: Big block Whiplash - heartache or happiness?
 

So it's safe to say that you've got no idea what a hand launch with a 8x10 would be like.

RE: Big block Whiplash - heartache or happiness?
 

Still not worth it.

RE: Big block Whiplash - heartache or happiness?
 

I found what you're saying [to be true] with the same sized delta powered by a Webra .50. I tried every prop I could get my hands on and the best prop overall was the APC 9x8 sport prop. The 9x8 made it launch practically hands off and it runs 150 at a relatively low and boring tone. The Webra .50 is a far cry from the OPS .60 though.

RE: Big block Whiplash - heartache or happiness?
 

Well when using a high performance "big block" such like a 10 to 15 cc ducted fan or speed engine a carbon fiber 9x8 prop in fact wouldn't provide enough engine load.

A CF prop sized 8.5x10 would be perfect for the OPS .65 RIRE in combination with a delta airframe => excellent top speed (about 200 mph) in combination with still strong accellaration after the turns.

You could also try a CF 8x11 for a Whiplash-type airframe but I doubt gaining more top speed than with the 8.5x10...

RE: Big block Whiplash - heartache or happiness?
 

@MJD

When your buddy Ed and you are going to mold carbon fibre props you first have to determine the airframe specs.
[ul][*] If that speed prop will be applied in combination with a conventional type of speed airframe (or ME-163 style) you can apply more pitch than 10".
[*] A WHIPLASH or similar type of speed delta on the other hand is limited to about 10" of prop pitch to find the most promising overall performance results between top speed and acceleration.
[/ul]

Please - for safety reasons - design the prop hub of the master prop thicker and larger in diameter than all of the above listed APC prop sizes. So the prop hub should feature ca 1" in diameter and 15 mm of height.

RE: Big block Whiplash - heartache or happiness?
 

You're right, and as ILJ also reminded, 9x8 is too small a load for either the .60 VAE or R/C .65 speed, unless I suppose the entire flight was straight up.

ILJ: don't worry, I'll be making sure I have hub strength enough. All the warnings to date are duly noted! And I plan to stick with no more than 10" of pitch for now and adjust rpm as needed via diameter. Although I do have a Profi 12-10.5 which looks like it would be a potential candidate to trim down to 8.5-9.0" dia, and it has plenty of hub: 27mm diameterx 15mm deep. This is as a mold plug of course, not to run the prop itself. The other base prop would be an APC 10-10 as suggested before. I can get "fancy" later if I need to.

I think anything anywhere near 200 will be just fine for me at the moment [:-]. I have to think about my aging reflexes and eyesight against the desire to be an RC hooligan.

MJD