Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Designing for ultimate speed

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Old 05-31-2007, 11:12 PM
  #1  
The Raven
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Default Designing for ultimate speed

Can anyone direct me to some good websites, or other information, on how to build a super fast R/C plane?

My goal is to build the fastest plane I can within the following criteria:

1. Something in the normal 46 sized range - primarily to fit into the car.
2. Use conventional construction materials - balsa and the like, maybe a bit of fibreglass or carbon rod.
3. Use a conventional prop driving engine - Something like a OS 46AX
4. Run on standard nitro blends - approximately 10%
5. Be able to take off from the ground with a level of control - perhaps on a dolly
6. Circuit our field without being a handful in the air
7. Perform straight line high speed passes down a 230m (approx 700ft) main runway
8. Belly land at a reasonable speed - knowing a hot landing will be inevitable
9. Be safe!

Importantly, I don't want to get carried away with anal amounts of research with wind tunnels, computer models, CAD, laser cutting etc. At the most I'll sketch out a rough design and build from that....no fancy drawings etc.

Yes, I'm a competent flier and builder. I will not cut corners on safety!

I guess my first port of call is to look at the designs used for electric pylon racers. That should give me an insight into the basic design elements necessary for speed.
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Old 06-01-2007, 01:20 AM
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Mike Connor
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Default RE: Designing for ultimate speed

You should post this in the "Extream Speed Prop Plane" forum. A lot of the talk is about normal fast airplanes but if you look around over there you can get info on the World record holders in Europe. However, the engine you have is a far cry from what the speed speed guys are using but you could break 100 mph on a Q-500 type plane.

I just realized you have been in the speed forum. There is some good info there but you may have to search for it.
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Old 06-01-2007, 05:13 AM
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Default RE: Designing for ultimate speed

ORIGINAL: Mike Connor

You should post this in the "Extream Speed Prop Plane" forum. A lot of the talk is about normal fast airplanes but if you look around over there you can get info on the World record holders in Europe. However, the engine you have is a far cry from what the speed speed guys are using but you could break 100 mph on a Q-500 type plane.

I just realized you have been in the speed forum. There is some good info there but you may have to search for it.
Thanks, I wasn't aware of the Extreme Speed forum when I originally posted it but I did find it shortly after.

My mention of an AX was merely as a starting point. If there was a similarly affordable engine that was better suited then that would be fine.
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Old 06-01-2007, 05:38 AM
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Default RE: Designing for ultimate speed

Build a Quickie 500.

Leave off the gear.
Shorten the span.

Learn to fly it and then build a speed wing for it.

It will provide you with an entirely functional testbed. It will provide you with a pilot training tool that you really will need.
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Old 06-01-2007, 07:07 AM
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Default RE: Designing for ultimate speed

This airplane for example:
http://www2.towerhobbies.com/cgi-bin...&P=SM&I=LXMCN4
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Old 06-01-2007, 07:33 AM
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Default RE: Designing for ultimate speed

Your engine selection is going to severely limit the speed you can achieve. It will have to be prop'ed to turn 16,000 in the air to reach it’s peak power, which is only around 1.6 hp. With a stock Quickie 500 design it will top out at around 120 mph, but with a slightly smaller cleaner airframe you might reach 140 if the drag is low enough to turn a slightly over square prop.
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Old 06-01-2007, 08:16 AM
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Default RE: Designing for ultimate speed

ORIGINAL: HighPlains

Your engine selection is going to severely limit the speed you can achieve. It will have to be prop'ed to turn 16,000 in the air to reach it’s peak power, which is only around 1.6 hp. With a stock Quickie 500 design it will top out at around 120 mph, but with a slightly smaller cleaner airframe you might reach 140 if the drag is low enough to turn a slightly over square prop.
What engine would you recommend, I only used the AX as an example? I need to keep my choices to locally available engines (Australia) that won't burn a hole in my pocket.
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Old 06-01-2007, 11:13 AM
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Default RE: Designing for ultimate speed

Jett and Nelson make engines that have the type of performance you want – lots of RPM and about double the hp. Lots of them are available used because of the newer long stroke design that makes all of the earlier ones obsolete. That also cuts their price to about half of the new engines.
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Old 06-02-2007, 02:09 AM
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Default RE: Designing for ultimate speed

Unfortunetly if you want to go truly fast you need to buy the HP and revs to do that and that costs serious coin. If you look through the engine options in Extreme Speed Prop Planes you'll find that the more regular priced "sporty" engines can fly quick but do not really qualify as "extreme".
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Old 06-02-2007, 04:14 AM
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Default RE: Designing for ultimate speed

OK, now I'm going to show my ignorance. I've never heard of Jett and Nelson and can only assume they are either US or UK manufacturer(s).

Anyone direct me to a website for their engines? Would like to check them out.
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Old 06-02-2007, 08:03 AM
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Default RE: Designing for ultimate speed

Quickie 500 was originally intended to be a entry level pylon racing class. The rules called for 500 square inches of wing area in a constant chord wing with a minimum thickness of around 12% of the chord. The engine must be totally exposed and have a side exhaust and throttle. (sport engine in other words) The fusilage must have a square cross section and there are probably a bunch more rules that I can't think of at the moment.
Some clubs have classes with further restrictions for example, having to use an engine that costs less than $100 dollars.

Anyway, there is a lot of built in by the rules drag in a Quicky 500. If you are not constrained by needing a plane that is legal for pylon racing, you might check out designs for electric hot-liners and convert to glow or build a state a of the art QM-40 plane ignoring the side exhaust and exposed muffler rule. Effective cowlings for engine cooling and in the fusilage mufflers go a long way in reducing drag.

Drag is the enemy of speed. When you are trying to go 200 mph, everything matters. Exposed control surface horns and linkage, landing gear, exposed radio switches, retractable landing gear that retracts into holes that stay open etc.
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Old 06-02-2007, 11:59 AM
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Default RE: Designing for ultimate speed


ORIGINAL: The Raven

OK, now I'm going to show my ignorance. I've never heard of Jett and Nelson and can only assume they are either US or UK manufacturer(s).

Anyone direct me to a website for their engines? Would like to check them out.
http://jettengineering.com/
http://pspec.com/
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Old 06-02-2007, 01:39 PM
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Default RE: Designing for ultimate speed

I see that you didn't start a thread on this in Extreme Prop yet. I've moved it there since you'll get much better advice based on where this thread is going over there. If you end up wanting to have a go at the model design itself instead of just buying a plan, kit or ARF then post in Aerodynamics or Scratch Building with design questions.
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Old 06-03-2007, 08:39 AM
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Default RE: Designing for ultimate speed

How fast are you looking to go?

It will be easier to answer your questions knowing that.
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Old 06-04-2007, 01:30 PM
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Default RE: Designing for ultimate speed

As Dave noted..... do you have a target or goal?

Just as a baseline, a very basic Q-500 design (box fuselage, rectangular 12.5% wing, 500sqin, 3.5 lbs .... nothing difficult) with a stock, well broken in Thunder Tiger .40 pro (or alternatly your OS46AX) and a simple 9x6 prop (10x7 for the .46AX) will easily hit 120 mph. And it has fixed landing gear.

Again, as a point of reference....
Right now, the fastest "40" size planes are the FAI racing aircraft, specialized engines, computer designed composite airframes - those hitting 200-230 mph.

Beyond that, there are endless design considerations and powerplant options.

From your original question.... it sounds like you wish to build a simple airframe with given size constraints. You will find a number of suitable designs in this forum (look up Angel's Rifle, and some of the delta threads) Also, look at some of the pattern aircraft designs (pattern, classic pattern forum). There are a few of the older .40 size designs you will find in there, and most of the .60 size designs scale down well.

One parting though..... the MAIN thing you can do with aircraft design to get speed out of it, is addressing the engine installation. You will want a cowled in engine, and cowled in exhaust system. The engine/muffler/pipe... what have you.... sitting out in the breeze is a HUGE amount of drag. Not always easy to do, not alway pretty.... but done right can result in the best speed gain. Look at the Phenom thread for a decent example, and the FAI and older F1 designs for more refined examples.

Bob
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Old 06-05-2007, 07:01 AM
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Default RE: Designing for ultimate speed


ORIGINAL: bob27s

One parting though..... the MAIN thing you can do with aircraft design to get speed out of it, is addressing the engine installation. You will want a cowled in engine, and cowled in exhaust system. The engine/muffler/pipe... what have you.... sitting out in the breeze is a HUGE amount of drag. Not always easy to do, not alway pretty.... but done right can result in the best speed gain. Look at the Phenom thread for a decent example, and the FAI and older F1 designs for more refined examples.

Bob
Sorry to sound critical, but I would think that the Phenom wouldn't be such a good example as it looks like it still leaves a great deal of the engine exposed in the breeze, especially when compared to the speed cup contenders.. although I still think it's the best looking delta bar none
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Old 06-05-2007, 07:41 AM
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Default RE: Designing for ultimate speed

Critical is ok. You have a point, it is far from optimized, but provided as an example of where to start. Keep the frontal area to a minimum, keep the airflow as clean and useful as possible.

Compaired to a Whiplash or diamond dust, or a QM40 for that matter.... the Phenom design at least paid attention to cleaning up airflow over the engine.

Even most of the guys flying speed cup could do a bunch more to optimize.
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Old 06-05-2007, 10:13 AM
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Default RE: Designing for ultimate speed

Rifle
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Old 06-06-2007, 07:03 AM
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ORIGINAL: bob27s

Critical is ok. You have a point, it is far from optimized, but provided as an example of where to start. Keep the frontal area to a minimum, keep the airflow as clean and useful as possible.

Compaired to a Whiplash or diamond dust, or a QM40 for that matter.... the Phenom design at least paid attention to cleaning up airflow over the engine.

Even most of the guys flying speed cup could do a bunch more to optimize.
I have to totally agree with you on your point about the cowl on the Phenom when comparing them to DD's and Whips, the phenom has gone to the next step for sure as far as reducing dirty air flow....

As for the the speed cup contenders , again you are totally correct... there a few more improvements that they can make..I noticed that on close examination, some are immediately obvious and some are more subtle to spot..

So as far as to help Raven along to achieve his goal.. in respect to being able to build but not wanting to go "the all out route eg all out engine, CF props etc" then I would suggest to make improvements that dont involve as much of the folding stuff .. therefore I think it would be better to focus on making the airframe as slippery as possible and make the most efficent cowling design you can come up with along with the rudimentry stuff like trying to hide control horns/linkages, along with a good "speed ' wing design....the down sidehere inregard to Ravens original post would be the need to at least do a little research on these aspects
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Old 06-06-2007, 05:00 PM
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Default RE: Designing for ultimate speed

Hi guys,

This is a photo of Chirs Callow's World champs '05 F3d Evo. You can see the engine & pipe cover & how small the air inlet is around the engine. It has a baffle shape to it to direct the air down past the engine through the cowl, out past the pipe.

F3d has a cross sectional fuse rule & this is the reason for the bulge like fuse, so you could remove the cockpit area to clean up the airflow.

The 2nd pic ic Chris Graham's new Evo for this years worlds, & this gives a look at the current thinking in F3d as far as aircraft plan form.

A good way of going quick compared to the rest of the crowd would be get hold of a second hand QM40/ F400, & putting a strong sport engine in there. Gives you throttle for getting used to it, & will still move along well. The Jett website has a few of them with SJ50's in the nose. The AX 46 wouldn't be too hard to get in there, it would just have to be balanced deferently with the heavier engine, than the Nelson/Jett that it was designed around.

Seeing as TheRaven is in Victoria, the AMPRA pylon Nats are on in Cootamundra this weekend. If you want a drive, you will see some of the fastest models in the country going around.

Tony...

p.s. I just like posting pix of my mates really fast planes
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Old 06-12-2007, 07:46 PM
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Default RE: Designing for ultimate speed

Hi guys, sorry for not responding but I've been away on business.

This may sound like a stupid question but is that F3D Evo available as an ARF? If so, what's the damage pricewise (and in which currency).

With work commitments being what they are, this is likely to be a slow project but it's something I'd like to chase.
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Old 06-12-2007, 09:11 PM
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Default RE: Designing for ultimate speed

Check out www.bigbruceracing.com

Its available as an arf, just bring a big check
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Old 06-12-2007, 09:12 PM
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Default RE: Designing for ultimate speed

Basic Kit about $750 plus shipping (made in Australia).

Custom paint extra, but very fair.
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Old 06-17-2007, 11:07 PM
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Default RE: Designing for ultimate speed

I know that pylon racers don't like dealing with zeros Dave, but you have one zero too many.[:-]
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Old 06-17-2007, 11:12 PM
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OOOps.

fixed it up, should be $750

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