200+ Mph Club

[Bart Vaio]

200+ mph Club? Alot of people are trying to join, but the FIRST person to break 200mph is........... (drum roll) .....................
(more drum roll)......................Craig Toutolmin. And he wasn't flying a hopped up double carbon F3F or F3B ship it was his own design, as some would call it a "homebrew" !!. The details are as follows, speed 202.4 Mph, run back up by a 201 and oddles of 190's radar gun, Stalker pro. Witnesses, Tim Bigley (operating radar), Bart Vaio ,Steve Situm (operating DV camera) and 2 other gentelmen that I just met for the first time, Site, Undisclosed NorCal location, Plane "Mofo" 15+ Lbs A.U.W ,35 +/- 0z/sq in. loading, radio Futaba. servos, really strong!!. Front side wind measured with kestrel wind meter gusting to mid 40's. Congrats are in order! good work Craig! All that sanding really paid off !!!!! The plane looked totally solid in the 190 to 200 mph range, no obscene bending going on, wierd twist etc. It looked like it was tracking well etc. hopefully Craig will tell us all the details soon. This day/site saw 4 plane failures 3 of which were failures due to flight loads, this speaks volumes to the homebrew or local builder theory of go fast planes. Also the use of F3F/F3B airfoils fwhich are not optimized for DS. Once again a big "atta boy" to Craig for being the first one to crack 200mph!!

[bjaffee]

Wow...congrats!

Was it a normal configuration airplane (i.e, wings, fuselage and a tail), or something more exotic? 15lbs on a 35oz/sq ft loading works out to 987 sq-in of wing, so presumably this was a pretty large plane?

[Frank S]

Wow! I guess that's why you weren't at Shell Ridge.

[GregG]

Bart, it was a pleasure meeting you today.

All I can say about today is WOW!! Tim had explained what you all were up to but it didn't all sink in until after actually watching it myself. I've emailed a couple of pics and a 5 MB, 15 sec. video clip to Craig and it's still uploading as I type this (from a friends computer). I started another thread in "Open Discussion" entitled We have a new DS World Record! (http://www.rcgroups.com/forums/showthread.php?s=&threadid=120089) and posted a few of the pics there. I'll try to do the same here.

Anyway, hope to see you on the hill again. Have a good one Bart!

Greg Gallegos
Ezone "Sport Planes" Moderator

[GregG]

Well it only took me until 3 AM this morning before I was settled down enough to get to sleep. While I was up late I got one video clip uploaded. That 15 sec. video clip is now on Silent Flight Online. I have to appologize for the clarity and no sound as it was taken with a 3 yr old Olympus D-490 Digicam with 2.1 MP. The wind made so much noise that you probably couldn't hear the plane anyway. That's all I have so that's what we get.

The video is in .mov form so you'll need Quicktime to watch it. Search gliders there for "202.2 MPH Dynamic Soaring New World Record (http://www.silentflightonline.com/Site/Members/ImageBase/Images/1246.mov)" Hope you enjoy! :D

[Craig Toutolmin]

I'm sure glad I popped the 200 mph cherry yesterday! Dave Reese hit 206.6 mph today with his BP Wizard. Unfortunately his tail blew off the plane in what seems to be typical Wizard fashion and led to a very scary situation for the camera man and radar people.

Congrats Dave! No, you da man!

Craig

[GregG]

Wow, I just set my Quicktime for "Double Size" and to "Loop" the movie so I could watch it over and over at a larger size. By doing this you can see Craig flying and the Radarman aiming at the plane while it is headed uphill. The reason I say WOW is take a close look at the wing tips as MoFo hits the boundery layer. There is noticable wing strain under that massive force. They actually get a bit of upward curve to a normally flat wing but the MoFo takes it all in stride. Another kudos goes to Craig for a great job designing and building this one.

So Craig, whats next on the building board, or should I say out of the vacuum bag? :D

[Bart Vaio]

WOW what a weekend eh? Congrats to Dave and Craig both for a job well done! Watching Dave fly that Wiz, which was unballasted, around that hill in excess of 170 mph for a looong time (sometimes faster into the 190's) trying to chase down a 200+ speed was a completely different style than Craigs record setting run. Just goes to show no single method or theory is RIGHT, but we can all chase these records down different paths. Craigs plane, by design and construction, seems well suited for larger open circles and the added weight provides some pitch and roll stability, while Daves plane being comparatively light, but enhanced for DS, had to fly much tighter circles that were at times flown very aggressively on the elevator. Kudos to you both it took alot of pilot skill to maximize the energy avalible on the hill both days!!! On another note Dave's tail did blow off in true Wiz fashion, this was at 206+ mph, by the time i had DECIDED which direction to run,duck,hide the tailless plane already shot by....Good thumbs by Dave averted a potential accident, as these record speeds become faster radar gunners and video crews will need to pick their locations with an eye toward safety as plane failures will become more and more violent as speed increases. Maybe portable sheilding (like a 1 1/8" sheet of plywood) could be a possible solution, I dunno the answer just thought i would throw it out there...Details, on radar gun Craig, with me hiding behind him. On the DV camera down the hill, Tim Bigley (Great footage Tim!!) In the Air, Wizard Compact DS, Radio Futaba, servos Volz, frontside wind around 30. Site NorCal undisclosed, speed 206.6!!
nuff said..

Bart

[Craig Toutolmin]

I think you are right Bart. We need to build a Wizard wall until they get the tail thing figured out. ;)

[Ade]

Well done Craig and Dave. Its nice to see it do able with a strong F3F machine as well as an all out specialist machine.

Why is the site undisclosed? not sure it is fair play to claim a record and not tell us where...

Ade (devils advocate)

[bjaffee]

Wow again...congrats to Dave.

So did the center "v" piece blow off the Wizard v-tail?

[Craig Toutolmin]

Ade,
The main reason for not posting the name of the site is to minimize the concerns of people who come accross it in a search engine etc. We might have to name it something other than its official name so flower finders/hikers don't get startled with high speed plane failure stories when looking for a site. It is the smart thing to do. Just like Brett does not disclose the Malibu site location. It is about site preservation. If someone wants to make a speed attempt they know who to contact and it will happen.

Brett,

Without mincing any words, the Wizard is a dangerous plane. There is something very wrong with the tail design/construction. I think it centers around the tail design. Dave added lap joints over the butt joints and this time the tail twisted off at the aft end of the boom. The remnants showed the tearing. The pivot point is very far forward causing a considerable load on the servo/pushrod assembly (which is in compression with up elevator). There are several failure possibilities between each servo and the full flying V that it controls. If one side fails you have a propeller mounted on the back of the plane.

Craig

[osborn]

Craig,

It is probably more fair to say flying the Wizard too fast makes it a dangerous plane.:D

As far as them "getting the tail figured out," I don't see it happening. So far the response has been to simply strengthen the tail region, not redesign it. There seems to be a fundamental problem with the the flying tail fluttering at high speeds. Reinforcing the closeout region has just caused the failure to migrate into the boom.

They do however offer a conventional hinged tail. Has anyone tried one of these?

-- James

[Bart Vaio]

I like the ring of that Craig hehe " A wiz wall" ...

Bart

[Daemon]

Just a bit of sobering trivia for ya..

A .357 Magnum (highest power I could find info for)
0.01166 kg
359 m/s
751 joules of kinetic energy

A .30-06 rifle bullet..
0.01166 kg
822 m/s
3939 joules

versus
15 lb glider going 202mph.
6.8 kg
90 m/s
27,540 joules

And the last is the only one of the three you actually will point at yourself, every 5 seconds, over and over and over ;)

I'm thinking to really make a DS-proof wall for radar operator/pilot protection you should consider more than a thick 4x8 sheet of plywood. Perhaps plywood with layers of kevlar and chainlink fencing over it, and hope that if it ever hits, the heaviest pieces don't manage to make it through in tact. I have seen radar guns used through chainlink without a problem so you'd cut a hole in the board and aim the radar gun through the fencing and hope the fuse doesn't line up with the opening.

And I'm not here to say what's being done now, shouldn't be done. Far from it. It's cool as hell. But consider all the possible failure modes. Wing folds, tail folds/comes off, pushrod breaks or comes loose, flutter, servo arms break, battery failure, rx failure, radio interference, severe turbulence, brain fart.. Pretty amazing stuff.

ian

[Craig Toutolmin]

Ian,

There is no arguing with the numbers. They are downright scary. After yesterdays incident I'm inclined to set the gun on a tripod and let the pilot go at it, especially with planes that have a history of failure. Wing failures usually result in much of the energy being dissipated VERY quickly unless the nose breaks off. As with one of my early home brews and a couple Icons, the detached nose is very dangerous and hard to see.

Craig

[Ade]

Craig,

We have had to create a name for a couple of sites. But for differing reasons. One of them is a club controlled site, they have nagotiated with the farmer for parking and as such want to make sure the visiting people comply.

The model destructution problem is more about pilot resposibility, at least the failures I have seen the model was being seriously abused and showing signs of failure long before it actually failing.

Also the people that panick don't realise just how much DSing goes on verses the failures. I have been DSing for getting on for 2 years. I have seen approx 5 inflight failures and a number of pilot error crashes a long with a similar number of model failures resulting in a controlled landings.

All of the crashes were well away from the pits/pilot areas. The landings were mainly due to aileron servo mount/gear failure.

Now compare this to normal front side crashes and ok, the inflight model failure goes to almost zero. but the pilot error goes up to maybe 3-4times. Ok more people fly front side than DS so the crash per pilot is probably lower for front side. But each crash has the possibilty to kill somebody.

DS has a reputation as a model breaker. This tends to scare a lot of people off flying it with crunchy models. So it sort of self regulates in that respect. Those that are new to it generally try it with a foamy first these still have the capability of damaging somebody but I doubt if they would do any long lasting damage.

As for the protection, Daemon wrote

"A .30-06 rifle bullet..
0.01166 kg
822 m/s
3939 joules

versus
15 lb glider going 202mph.
6.8 kg
90 m/s
27,540 joules"

but what is the PSI of the impact? All though a bullet has less energy it is stronger and smaller so the force per square inch may well be higher than a model.

The model will also deform a lot more on impact disipating the energy.

just my 2p worth don't know how much truth there is in it :-)

Ade

[bjaffee]

Mmmm...perhaps a Wizard wing on a different fuse. At least it sounds like the wing works pretty good?

Craig,

Does the Mofo have a flying tail or a seperate elevator? Can't tell from the picture. Having seen the tail on Brian McLean's Extreme, I've been intrigued by the conventional elevator/stab design he uses, with the "pull for for up-elevator" design.

BTW, did the Wizard in question use the stock (very short) overwing flap and aileron linkage? Or was it modified to use larger/conventional underwing control horns?

[Bart Vaio]

Angle of the dangle needs to be addressed. You can bounce a bullet off water if shot at the right angle. Any saftey enclosure should probably be designed to deflect the load as opposed to absorbing it. If you wanted to set up a "mofo" wall 90 degrees to the ground you would probably need a crane to get it to the site due to the strength needed. I agree a simple sheet of plywood may not cut the mustard so to speak, but one reinforced like you said and setup at an angle optimized for deflection rather than absorbsion may be the ticket...

[bjaffee]

It might not be the perfect solution, but if nothing else a motorcyle-type helmet would probably not be a bad idea (and it's portable).

[Craig Toutolmin]

Ade,

We are working on a suitable name for the site. The Wrecker is already taken. The Thrasher, Mangler, Mauler, Mishap, Cash Deposit, Stress Tester and Carbon Confetti Hill are being considered.

Brett,

No doubt the wing works well on the Wiz. I was disappointed when they moved away from the three piece wing and traditional V-tail. The Wiz (brand spanking new Ade) had stock style control horns that looked to be made of brass.

The Mofo has a split elevator that is actuated by two tail mounted servos pulling for up elevator.

[GregG]

James Osborn, Welcome to RC Groups! :D

Long time no see James, it's good to see you here! The whole thing was pretty amazing. I went to the local glow power field today and a couple of guys already heard about this. All I wanted to do was to get some float flying practice in before the pond drys up. They twisted my arm and made me retell the story for an hr. before I actually got to concentrate on my own flying. ;)

Ian, those figure are pretty scary. I'd be willing to bet that the chainlink fence wouldn't even hold up to all that force. The fuse and ballast weight would probably extrude itself right though an opening. :eek:

[osborn]

Dudes and Dudettes,

I had a chance to check out this site today. Tim Bigley took me and Brian Yumae (another East Bay flier) there to check it out. It seemed like the energy there today was "typical" for this site, somewhat lighter than Saturday, but according to Tim similar to yesterday when Dave did 206+.

There is a lot of energy here.:D I don't have any bullet proof planes in my arsenal at this point in time. This will change in the next few months and I hope to join at least the 150 club. Today with planes not up to the task, I found the game was trying NOT to extract the most energy from the air!:eek: It was pretty easy to go wicked fast. Nothing blew up today but Tim punished a Y2K nearly to oblivion a couple times.

As for Dave and the Wizard, congratulations and very cool, but a high price to pay. The witnesses of Craig's 202+ seem to all agree that it looked like the Mofo's potential was not exhausted. I look forward to witnessing all this plane, pilot and location can do together.

-- James

[Daemon]

Ade, I'm not panicing, and the fact is, very very few people fly 3m gliders *toward* themselves and another person over and over at 200+ mph on the frontside, whereas this is an activity that is increasing in frequency on the backside. You're right there've been a lot more total crashes on the frontside but the speeds are lower, the weight of the gliders are usually lower, and the flights don't involve flying through severe shear layers repeatedly with associated airframe abuse and the requirement for lightning pilot reflexes. Also, I bet if you looked at the actual time in the air versus the number of ballistic crashes/failures, DS's record would look somewhat worse.

All I'm saying is.. it's got to be considered. If it were only yourself standing in front of it, that'd be one thing , but there's at least one other person to consider given current speed measurment techniques.

BTW.. Want a softer mass to compare the energy to.. A 170lb human travelling at 60mph has the same kinetic energy. So I suppose it could be compared to riding a motorcycle without a helmet or leather jacket and say making contact with a relatively stationary object. Dissipate the energy any way you want.

ian

[Dynamic_G]

Congratulations Craig for cracking the 200mph barrier. I've been watching and waiting to see who it was going to be. I think its a fantastic achievement. What sort of noise does that Mofo make?

[Mark Wood]

Pardon me for taking so long to comment but GEEZ, Craig! That's quite the accomplishment. DS is tricky in the first place and I for one am lousy at it. To push past 200mph is beyond my comprehension and what it takes to do it.
Congratulations and a well done! :)

mw

[Ade]

So come on craig, we all want to know what makes the Mofo capable of these speeds in what looks like a relatively relaxed way.

What makes a mofo a mofo compared to the beefed up F3F machines?

[Craig Toutolmin]

The Mofo is a completely different animal from an F3F/F3B plane. I tried to explain some of the details in the "ultimate DS plane" thread but the focus never strayed from the span loader.

[hkrussell]

Did you bag the wings or press them?

What servo's did you use in the wings?

The skin was a single layer of 5.7 c/f right?

Ken

[Reed]

HS85s I bet. And no spar because they take too long. Also, and this is really letting the cat out of the bag, Craig told me the whole plane is EPP.

[Craig Toutolmin]

"Did you bag the wings or press them?"

Both. Bagged, then pressed during the post cure.

"What servo's did you use in the wings?"

HS5645's Ailerons
HS5945's Flaps

"The skin was a single layer of 5.7 c/f right?"

That is correct for the center panel. The tips are a little more complicated.

I would not get too excited about the construction until it has gone faster.

[bjaffee]

Okay, since Craig is being secretive.. :)

Here's some (very obvious) observations based on the few pics of the Mofo....

1. Very narrow chord flaps and ailerons (are the flaps very effective Craig?).

2. Unswept planform? Not sure about this because it's hard to tell in the pictures if the LE of the tip panels sweeps back, or if I'm just seeing the angle from the dihedral break.

3. The fuselage is extremly large just behind the wing, and the diameter of the tail boom stays quite large. It looks like the minimum diameter of the boom is as large as the max diameter of the booms on most F3F planes. Somehow I don't imagine it flexing too much.

4. In one of the pictures it looks like the wing might be mounted above the fuselage a bit...but perhaps the center section wasn't completely attached in that shot.

5. Does it have a rudder?

Okay, enuf speculation.

[Ade]

Originally posted by Craig Toutolmin
The Mofo is a completely different animal from an F3F/F3B plane. I tried to explain some of the details in the "ultimate DS plane" thread but the focus never strayed from the span loader.

Nows your chance :-)

Ade

[speedster]

You the man! I`am looking to join the club next week at parker with my new carbon NYX!:D

[owdear]

Was the Wizard Compact ballastest at 206mph???

thanx

Richard

[markdrela]

Originally posted by Craig Toutolmin
Both. Bagged, then pressed during the post cure.


What's the airfoil? The reason I ask is that with the Reynolds numbers pushing 2 million in the center, the usual fast RC sections (RG15, etc) aren't so hot. You want something closer to a full-size sailplane wingtip section. These will also be thicker which is obviously beneficial for structure.

Also, as any full-size glider pilot will tell you, airfoil accuracy and general surface quality is very critical compared to what's needed for most RC gliders. DS speed is where molded construction would pay off more than in any other soaring event.

[Craig Toutolmin]

I'm using an MH24/S2055 combo. The Wiz uses SD2030.

[t_seitz]

[QUOTE]Originally posted by markdrela
[ the usual fast RC sections (RG15, etc) aren't so hot. You want something closer to a full-size sailplane wingtip section.

Could you give some examples of full-size sailplane airfoils that would be appropriate for a larger DS plane? Are there R/C sections that have similar characteristics? How do these higher reynolds number optimized sections differ from R/C sections other than in thickness? I would imagine the location of max thickness, camber, LE radius, etc. would be important.

Tom Seitz

[markdrela]

Originally posted by t_seitz
Could you give some examples of full-size sailplane airfoils that would be appropriate for a larger DS plane?

I don't have any that would be best for DS, since they are normally designed for larger CL's than what you guys run. But in general, they have a larger max thickness (12-15%) which is farther back on the chord. More importantly, they have more aggressive favorable pressure gradients which promote laminar flow in the face of the large Re. The larger thickness gives laminar flow over a relatively large Cl range, which gives a nice wide drag bucket. And the larger thickness is obviously structurally beneficial.

The MH24 at 2 million has premature transition and a very narrow drag bucket as a result -- between Cl=0.05 and Cl=0.2. You must be getting a lot of turbulent skin friction in the higher-Cl parts of the orbit. Not having a molded wing makes this worse. Look at Hepperle's warning on the MH24 page:
"Needs perfect construction methods (machined moulds recommended)."
The S2055 is even more demanding in this regard.

All this really calls for a more careful airfoil/wing-loading design study. My gut feeling is that you want airfoils in the 11-13% thickness range, with a slightly narrower wing to take advantage of their larger CLmax. You will pick up more laminar flow AND less wetted area. The thicker airfoils will certainly make a narrower wing structurally feasible.

[Craig Toutolmin]

I have spent quite some time on MH's page. Machining molds is not feasible for me. I have to make due with templates, filler and a lot of sanding. Are they exact replicas? No. They are only as good as I could do with my patience. When I was starting to get burnt I'd say 199 mph for the motivation to keep going. I did not want to get stuck at 199 mph.

At 200 mph the MH24 section re averages 1.5 million. The s2055 550k-1.25 million.

Both foils show low drag in the CL .3-.5 range at their repective Re's. This is shifted vertically with snap-flap to .4-.6. This combined with similar cm's, zero lift angles and the low speed performance of the s2055 for launching/landing persuaded me to choose this combo.

A guy that makes dentures for a living is bound to make some aerodynamic blunders. While this sounds like a big one, I'll learn from this mistake.

[Tony D.]

I am in the last stages of building a new wing for my Rimmer DS design using the Eppler 231 which can be seen here:

http://www.nasg.com/afdb/show-airfoil-e.phtml?id=1159

I built a set of wingeron wings to try it out and it looks promising but as for DS top speed I am hopefull but not so sure.

With a 12.34% thickness and a 8" root chord and 3 tapers over 98" span it falls into the thick section, narrow wing criteria.


Comments anyone?



Tony Dempsey

[markdrela]

Originally posted by Tony D.
I am in the last stages of building a new wing for my Rimmer DS design using the Eppler 231


I'm not familiar with the E231. But a quicky look at the polars between 1-2 million shows that it's very close to what I had in mind. It looks like it will want 1-2 degrees of reflex in straight flight, and 2-3 degrees of camber for high-CL pulls. Just about right. My guess is that this airfoil wants the wing narrowed 15% compared to a MH24 wing. The E231 wing will still be thicker.

I also did a quick look at a 50/50 blend of the MH24 and E231, and that also seems very good.
An 8-10% narrowing is probably more appropriate with this section. Might be a good less-radical first step.

[Tony D.]

Thanks for the info. Mark, I was hoping my interpretation of the polars was correct.

I am hoping to make 200MPH or better with this plane and be able to land it in one piece.

With the 231 I was able to get a very beefy carbon capped spar in the wing and the thicker section has the added benifit of making it less of a shoe horn effort to get the servos in the wing.


Tony Dempsey

[Ollie]

Congratulations, Craig. It looks like a conventional configuration is the way to go and your MOJO can easily be refined for even higher performance with out resorting to anything as radical as a spanloader configuration.

[surfimp]

Just curious what you all think of flying wing designs & DS...noting, when I ask this, that the current speed record has been set by conventionals.

Does the lower drag promised by the flying wing offset the reduced efficiency inherent to that design type (due to the need for the wing to both lift and stabilize)? Just curious for your thoughts, as I've not seen or heard of many flying wing contenders. But, as Rumsfeld says, "Absence of proof is not proof of absence".

[bjaffee]

I keep hearing tidbits about an 8 foot composite Bluto being made by the NCFM guys (or guy) to break a DS record.

[Craig Toutolmin]

Hey Tony,

I really like the looks of the E231. I'm going to put that one in my list of favorites.

With a wingeron design one of the challenges is to keep the bearings/shaft from binding under load. The other challenge is to control twisting loads. There can be huge twisting loads on the wing that will require strong servos. Traditional wings simply transmit this load to the center panel with no load on the servos. Dave Reese told me of his experience at the 1998 Speed Trials with his Kestral (pitcheron). At 120 something the plane started spiraling out of control in the dive as the twisting loads from the wings dominated the servos.

Craig

[Daemon]

Originally posted by bjaffee
I keep hearing tidbits about an 8 foot composite Bluto being made by the NCFM guys (or guy) to break a DS record.

My understanding is that it's not only made, but has flown. The problem I'd see with is that it's big and fast and very crunchie, and lands nose down in the dirt at speed. Its first ballasted flight is liable to be its last.

The problem of landing any big composite flying wing safely may ultimately be the limiting factor in their quest for DS records.

ian

[Tony D.]

Hi Craig,

I was at the Speed Trials when Dave was having those problems, it looked like the Kestral had real potential but the lock up issue eliminated it from contention.

Before I commited the resources and time it takes to build a full DS ready wing I wanted to try the 231 on a easy build wingeron.

On the front side it was fairly impressive and I could really hammer the elevator, I then dropped into the back side at a spot in British Columbia I call the Trash Heap and the potential looked so good that I went ahead and built the DS wing with the 231.

I have a few more hours of work to make my latest Rimmer good to go and I am hoping to get to California in June or July for a go at the big numbers.


Tony Dempsey

[surfimp]

Originally posted by Daemon
The problem of landing any big composite flying wing safely may ultimately be the limiting factor in their quest for DS records.

Amen. A buddy of mine has built a 72" composite wing that we've clocked at some very high speeds, but the plane has no flaps, spoilers or anything else...just elevons. Landing is always exciting!

[bjaffee]

Originally posted by surfimp
Amen. A buddy of mine has built a 72" composite wing that we've clocked at some very high speeds, but the plane has no flaps, spoilers or anything else...just elevons. Landing is always exciting!

I'd think on a large enough flying wing you'd want to add seperate elevator and aileron controls and use them for some sort of crow braking.

[Ade]

what about good old fasioned spoilers? These can't flutter!!

Ade

[Craig Toutolmin]

I have a bit of experience with big heavy planks. I flew a 9 lb 2X Zipper for a few years that was qite a bit of plane to land. Launching was much like a heavy PSS plane event though the wing loading was under the FAI limit.

I built a 100" plank with JW foils. It had elevons and ailerons. They worked together in roll, inboard elevons for pitch, opposite each other for airbrake (almost impossible to set) and opposite each other on each wing half for yaw.
I gave up on trying to set the airbrake for landing. I would use it to slow the plane down at a safe altitude and then slide it in for a landing. Any type of pitch or roll input during the braking made a mess of things. This was one of the funnest sport planes I've owned. Outstanding inverted performance allowed for easy sub-sixty F3F without rolling.

[fraze1974]

Dunno if anyones tried split rudders ala the space shuttle?

Works fine on sport models, but i wonder if flutter would be an issue at DS speeds?

Anyone tried em?

[Dynamic_G]

I've built a 59" crunchie wing based on the Bluto planform and it DS'ed really well. Am preparing to built my next one but I am unsure how to scale it up.

[Raymund Reyes]

Hi Craig,

what ever happened to the Hans J. Co5 (from your old site :))
have thoughts of one in full carbon with a prefab spar, removable tip panels, and of course flaps!

Godspeed and see you on the flipside,
Ray

[Craig Toutolmin]

My Allen Halleck Razor aside, the swept flying wings suffered from high speed elevator stall. I believe it was the wing twisting (wash-in) that dominated the elevator. Fences, snap-flap and powerfull servos made no difference. Everything would be cool up until a certain speed then the elevator went away. The CO5 was around SFL 15 after it hammered an oak tree during one of the elevator episodes.

[Raymund Reyes]

thanks for the reply and informative response Craig (as usual :))

PM ed ya...

Godspeed and see you on the flipside,
Ray

[Craig Toutolmin]

PM ing me is useless. I have five messages in there and have no clue on how to access them.

[cobalt]

Upper left: "My R/C Groups" (Yes, it's hidden)

Then, "Private Messages"

EDIT: "My R/C Groups" just moved. Now it's in the top header area next to Calender | Gallery | Member List etc.

hth,
Jason

[Micha]

Originally posted by Daemon


The problem of landing any big composite flying wing safely may ultimately be the limiting factor in their quest for DS records.

ian

How about a Jet like airbrake with parachute attached (it comes out when you open the airbrake)

[Bart Vaio]

One thing you gotta remeber and design for is daily flyability. If you have exploding parachutes or four cruciform fuselages or some other crazy stuff your plane will not be out there when the air gets good. I was just speaking with craig and he remarked about how fast the 200mph barrier came down, he thought it would've taken longer to crack. But once the Mofo was flying, in all it's beautiful simplicity, it was a matter of flying the plane when the air was RIGHT, then flying again. If you are packing your chute or repairing broken control horns etc. you are not flying. While you are not flying,,, planes with straight forward designs are out there maintaining 170+ mph circles waiting for the air to get just a lil better so they can attack the current record. My 2 cents, use the k.i.s.s. rule, cause the more you are in the air the faster you will go.


don't get me wrong, If Q (from James Bond) wants to send me a plane with exploding parachutes and rocket launchers i am all for it!! :)~

[bjaffee]

I am curious as to how easy it was to slow down the Mofo with such teeny-tiny flaps.

[invictarocks]

I have a JW that stops responding to elevator when it hits a certain speed.

--Everything would be cool up until a certain speed then the elevator went away. -

What the hell is it!??!?

[bjaffee]

Could be a number of things:

A: The servo could be stalling out.
B: The linkage might be flexing
C: The elevons could be flexing.
D: Some other part of the plane might be flexing (although that's usually more of a problem with conventional airplanes that have tailbooms)
E: All of the above.

The first thing I'd do is check and make sure your linkages are as tight as possible. Make sure they won't flex under load and that there is no (or very little) slop.

Next, check your elevons. It could be that they are moving at the point where the control horn is, but that flexibility is preventing the outer edges from moving when under load. If that's the case, take measures to stiffen up the elevons (by glassing them, for example).

Other then that, make sure your batteries are fully charged, and that your airframe is as stiff as possible.

[invictarocks]

I'm pretty sure the mechanical is doing it's job; I was referring to Craig's statement that he had a wing that would "stall the elevator" once the wing hit a certain speed. I glassed the elevons, and the linkage is direct with HS225mg servoes on a full charge. The JW flys fine unless I drop it in (to the boundry layer) going too fast. Then it just acts like there is no radio.... Craig?

[bjaffee]

I suppose that could be it. It's just that I haven't really heard that problem mentioned much with regards to the JW.

[Bart Vaio]

Sounds like a mechanical problem, that airfoil couldn't stall the elevator from a terminal velocity dive unless you had a REAL ugly tape job :)

[Daemon]

I can't speak to the JW (I have one, but it's never gone that fast), but I did discover a couple weeks ago that an M60 in a 600 foot terminal velocity dive produces enough downward aerodynamic pressure on the evelons, that both servos taped down into tight pots (but not glued in), were able to pry themselves loose from the wing eliminating elevator response, and eventually causing a slow roll over straight into the ground. Results not pretty.
http://www.houseofthud.com/rc/m60/m60-crash5.jpg

Point is, there is a huge amount of aerodynamic pressure on a plank style wing at those speeds, and if anything *can* give, it will. Flexing pushprod, servo moving in its pot.. or if not in a pot, just deforming the EPP itself, flex in the elevons.. etc..

Now I guess my question is, why are we talking about the JW in the 200+ mph Club thread? Only way a JW's going to reach 200mph is strained through a jet engine. ;)

ian

[bjaffee]

My friend's JW went over 600mph. It went to Hawaii with him. :)

[invictarocks]

You're all correct. I found through "bench testing" that the problem was a mechanical one. I was using ballstuds attached to the elevon horns, and they were twisting the horns enough to yeild under high speed. I changed the linkages, and flew the h#ll out of it today!

[invictarocks]

You're right on the money, bjaffee!
Thanks!