Belted Air Power Chevy V6 ...Indirect Update

[djvdb63]

Alternative Engine Fans...

Last night I emailed Belted Air Power through their website asking Jess Meyers if he'd come back here and post an update on the latest happenings with Belted Air. Jess replied this morning...answering the questions I had posed but declining to come back over here and "mix it up" again. Like so many he gets tired of the serial skeptics and the unending banter, etc. etc. In follow up he responded in detail to my many questions. He gave me permission to post his replies here. I have edited the paragraph structure just for ease of reading:

From: BELTEDAIR@aol.com A
Date: Thu, 28 Jun 2007 09:24:02 EDT

Subject: Re: Request for Update

Dan, I didn't know we had anything on the VAF forum's unless your talking about the fellow in Texas's site, it got to be nothing but people talking about harmonic devices that we decided they haven't nor will ever do anything but talk and thought it was a waste of our time.

Thanks for following us though. We are involved with several projects, a four seater from Australia using our FWF, Testing the Vari-Prop which is comming along great, and possibly a new drive for the smaller Chevy V-6 60 degree engines.

Jess

From: BELTEDAIR@aol.com
Date: Thu, 28 Jun 2007 14:23:18 EDT
Subject: Re: Request for Update

Dan, I'll try to ally your fears

1. The Vari-Prop has gone through complete engineering and partial re-design to simplify the maintenace of the unit.
2. Yes we trust it.
3. It shortens the distance slightly but will indicate 1500 fpm climb with a density altitude of 5000 msl.
4. Cruise speed is where you want to set it.
5. At 2500 engine rpm and 20" it indicates 130 mph for a fuel burn of 3-3.5 gph. This is one of the things were looking at is endurance.
5. It now can use the Lipps blade profile
6. It made the engine run much cooler at 110 F OAT
7. It will hopefully be on the market by this fall.
8. I think the projected cost was 5-5500.00

We have 75 RV's with the Chevy flying.

I think one fellow in Alabama removed his for a 200 HP Lyc.

Yes we have people one customer who purchased two, but unfortunately he died of an unexpected heart attack 4 months ago.

I'll try to find some in an area close to you. We have one in MN who did not use our whole package and mounted the radiator on the bottom of the plane and is very happy with it.

The planes perform like a 6 or 6A of 180 HP fixed pitch prop, except they use less fuel.

I haven't heard from Dr. Minichan for a while [RV-9A Chevy builder].

We are developing the new drive for the smaller hp requirement planes ie. Zenair, etc. and the Mustang by Titan.

Since the manifold is heated by coolant (190 degrees) or the exhaust crossover...carb ice has not been an issue. Not to say that in a blinding snow storm it wouldn't ice over but the air intake could possibly also, and my question is why are you flying single engine in known icing conditions without de-ice capability and hot props. We have not used carb [heat] and have flown into known icing conditions over a dry lake south of town with a 800 foot ceiling on the breakout. Ice on windshield, slight on wings engine ran fine. Will I do it again? NO. Minnesota is the farthest north where it's known cold and [there is] one in Calgary Canada. No [carb] ice problems. When it's that bad they don't fly anything.

Behind the radiator is an area where we have installed a flapper valve and take 190 degree air into the cabin and on to the windshield works great, no extra connections and clean air.

I still recommend calling ahead, come out and fly in ours, check with a comparable one with a Lycoming and make a valid decision.

Jess

[cjensen]

Great info Dan! I check BAP's site often, hoping for updates...

Thanks for posting!

[roadrunner20]

I was based at Las Vegas VGT in 2004-5 and entertained the thought of using Jessies's setup. I was quite impressed & would see him flying his RV quite often. He demo'd his FWF belted air sytem to our local EAA group. When I visted Jessie's hangar, he was always open to discussions.

I opted to go with a more traditional aviation option.

[rv6ejguy]

I appreciate Jess' input on the Chevy conversions and am very interested in his testing on the Vari-prop. I find some other information he has posted as amazing like 3.5gph at 130mph. Doesn't seem to add up as far as an RV drag polar goes with the SFC and available power at 2500 rpm. Comments like the aluminum block being too light also don't make sense. A Subaru is way lighter than even an all aluminum V6 and they always weigh as much or more than a Lycoming, even with a light prop.

The last 7A 180hp Lyco, FP I flew was able to true 174 knots at 8000 MSL on about 9.6GPH. I'm still waiting for an auto engine that can beat that.

Just playing the reality guy here and I'd love to be proved wrong with a side by side flight test against a Lycoming powered RV6A using the "fill the tanks Van's method" of fuel flow measurement. At least Jess is inviting people for rides and to compare.

[pierre smith]

Originally Posted by rv6ejguy

The last 7A 180hp Lyco, FP I flew was able to true 174 knots at 8000 MSL on about 9.6GPH. I'm still waiting for an auto engine that can beat that.

Just playing the reality guy here and I'd love to be proved wrong with a side by side flight test against a Lycoming powered RV6A using the "fill the tanks Van's method" of fuel flow measurement. At least Jess is inviting people for rides and to compare.

Ross,
Your 174 knot/ 9.6 GPH just about mirrors our numbers exactly. We occasionally get 177 knots solo and 2700 RPM with the Catto. A nearby friend has the 4 cylinder supercharged Egg in his -7 and goes around 162 MPH on 7 gph of mogas and loves the airplane. I recently gave him a BFR in it and it sure is smoooth.

Is there a geared box anywhere for the 350 Chevy?

Regards,
Pierre

[rv6ejguy]

Those are good numbers Pierre!

Lots of gearboxes available for the SBC. What do you have in mind?

[Rotary10-RV]

Originally Posted by pierre smith

Ross,
Your 174 knot/ 9.6 GPH just about mirrors our numbers exactly. We occasionally get 177 knots solo and 2700 RPM with the Catto. A nearby friend has the 4 cylinder supercharged Egg in his -7 and goes around 162 MPH on 7 gph of mogas and loves the airplane. I recently gave him a BFR in it and it sure is smoooth.

Is there a geared box anywhere for the 350 Chevy?

Regards,
Pierre

PIERRE,
There are several GB's for small block chevy. Check Team38.com. There is a Hi-Vo chain drive box as well Gershwinder (sic?) possibly? This looks like a compotent design. The owner has been trying to sell the company through the Contact! magazine though. Ross uses the Marcotte box, and they make one big enough for the Chevy. EPI Inc. did the gearboxes for chevys for the Lancair 4. Beautiful work but expensive. They (EPI) have done a lot of conversions and STC type work. Jack Kane is a real engineering perfectionist and won't release a product until he truly believes it's ready. That can be a PITA, but then you're less likely to make a smoking hole in the ground somewhere.
Bill Jepson

[DanH]

<<..it got to be nothing but people talking about harmonic devices that we decided they haven't nor will ever do anything but talk.. >>

I'm one of those people "talking about harmonic devices", without regret. I've done quite a lot more than talk about it, including designing a drive from scratch, developing a true viscous damper for use in parallel with a soft element, pulling live torsional telemetry, and helping with torsional prediction software. I deadsticked a failed drive (from a vendor), then bought books because a deadstick is a fine incentive for education. I've also flown both good and bad drives to OSH and S&F. My dues are paid.

There are two ways to design a propeller speed reduction unit. One is the brute force method, ie, hopefully make it stout enough to shrug off torsional issues. The other is to apply torsional engineering (torsional vibration is an old science), a path to lower weight and better reliability.

Brute force is fine, if you can stand the weight and have the time (years) for the "fly, break, fix, repeat" development cycles. That's Jess. His drives have torsional issues (all drives do, as the laws of physics vary for no man), but they are stout and Jess judges them good enough. If you're not interested in further development, discussions of torsional engineering are indeed a waste of time.

I have much respect for Jess as a pioneer. I don't think he should dismiss serious engineering discussion as unnecessary. You cannot design the next generation of propeller drive systems without the science.

[Rotary10-RV]

Originally Posted by DanH

<<..it got to be nothing but people talking about harmonic devices that we decided they haven't nor will ever do anything but talk.. >>

I'm one of those people "talking about harmonic devices", without regret. I've done quite a lot more than talk about it, including designing a drive from scratch, developing a true viscous damper for use in parallel with a soft element, pulling live torsional telemetry, and helping with torsional prediction software. I deadsticked a failed drive (from a vendor), then bought books because a deadstick is a fine incentive for education. I've also flown both good and bad drives to OSH and S&F. My dues are paid.

There are two ways to design a propeller speed reduction unit. One is the brute force method, ie, hopefully make it stout enough to shrug off torsional issues. The other is to apply torsional engineering (torsional vibration is an old science), a path to lower weight and better reliability.

Brute force is fine, if you can stand the weight and have the time (years) for the "fly, break, fix, repeat" development cycles. That's Jess. His drives have torsional issues (all drives do, as the laws of physics vary for no man), but they are stout and Jess judges them good enough. If you're not interested in further development, discussions of torsional engineering are indeed a waste of time.

I have much respect for Jess as a pioneer. I don't think he should dismiss serious engineering discussion as unnecessary. You cannot design the next generation of propeller drive systems without the science.

Dan, I believe you are the one that steered me to the Lovejoy site for in-line couplings. Thanks for that. You are correct that the path to a light drive is to handle the harmonics. If you do that you are much less likely to be supprised!

Bill Jepson

[DanH]

Bill, you're welcome. I like the Centaflex stuff.

Some folks like to argue that a particular drive system "has been flown for 1000's of hours", so it must be good. Here's an example of why that argument is false.

The plot you see below is an accurate computer simulation of the drive I purchased from a popular vendor in 1996. It was on a little I-3 Suzuki that made 68hp on the best day of it's life, or around 75 lbs-ft of mean torque.

The left axis is oscillating vibratory torque. The horizontal axis is RPM. At 1800 RPM, wide open throttle oscillating torque is 2300 lbs-ft (!). Mean torque at this RPM might not have been much more than 30 lbs-ft. This is resonant behavior, an unfortunate intersection of exciting frequency and the drive's F1 frequency. Resonance multiplies vibratory amplitude. Amplitude would reach infinity if it were not for the presence of a certain degree of frictional damping present in any real system. In this case the multiple is 76x mean torque.

Now look at a 4000 cruise RPM. Vibratory amplitude is around 50 lbs-ft, possibly less than mean torque, and very easy on the system components.

The failure of this drive would not be predicated on hours of operation. It would depend on the number of times the operator went to full throttle from idle, as in a balked landing or a simple touch and go. You could fly a million hours without failure if (2) you stay in the RPM range on the right side of the graph, and (2) push the throttle up gently every time you pass through 1800 RPM in order to keep the resonant peak as low as possible (resonant amplitude is roughly proportional to manifold pressure). Not a good drive by any means, but....

I failed this drive with 35 hours of T&G's and flight test. 10 hours later I launched for OSH, from Alabama, and had a pleasant trip by operating it carefully. Therein lies a second lesson: just because it flew to OSH doesn't make it good.