Category: mechanical

274 Simms

This was the first morning flight of the season
I left the buggy on the truck last night and so it was easy to hop out of bed and get out to the field. Conditions were great, a light breeze out of the SSW and 45 degrees. Takeoff was noticeably easier with the higher density air. To help the buggy get started I laid the ramps under the back wheels and it worked just fine. I climbed 1500 AGL and did a little exploring.

The only glitch was that the throttle cable tip got caught behind the idle stop and I had to force the lever back to get it to idle. This was fixed by putting a cord stop on the end of the throttle cable…no problem!

Rigging the Reserve Harness

After much fussing and fretting this is the way I have rigged the Reserve Harness


The bridal is on a seperate attachment aft of where the riser’s straps attach to the buggy. They run through the saftey straps below the “hang point loops” and on top and outside of anything that could foul during deployment. I selected the right side because I fly with the throttle in the left hand. It will not help with any torque issues but I don’t think torque is to much of a problem with the thumper 4 stroke.

Dialing in the Thumper

This evening I worked on getting to know the machine and making it more pilot friendly.

First I set up the foot steering with all new webbing.

Then I remounted the tach at a better angle so that I’ll be better able to read it in flight.

Then I lowered the back pad so that I can look over my shoulder. It might be too noisy but it feels good and the additional visibility is great!

Last I mounted another mirror in the crook where the bullet bars come together so that I’ll be able to see the wing during the first seconds of inflation. I’m hoping this will be a temporary training device and I won’t need it.

No Fly Day…

65 degrees

light and variable turning strong from west

Got to the field by 3. Driving North on C 470 I saw moderately strong air coming from the East by North East. At the Hampden & Simms is was manageable but I soon noticed that it was swinging on a huge ack from south to East To North and back again.

I was a little skittish especially since I had guess that the prevailing wind would be from the East.

There were a couple of spectators watching when I set up to launch and reported that the wind shifted from the west just before I started the motor. The wing came up crooked and collapsed quickly. It’s probably a good thing I decided to about. It continued to build and when i unhooked and kited the wing… it was strong and twitchy. Both tips collapsed in a sort of complicated pattern. It looked like it was going to continue building and I wanted no part of a spring air that was being filtered by the Rockies.

Mechanical I’m not sure that using shock cord for the A Assists is the best answer. I suspect that I didn’t get the tension equal and it was part of the reason for the bad inflation. Next time hook em up but still get on the A’s with your hands!

Cage Netting

Critics

During the Salton Sea and at the Flying Circus there were plenty of opportunities to stand around the Thumper Bullet and critique the design.Whenever the topic of cage netting came up I was surprised when the first thing said was, “Your going to lose thrust!” or “Its a trike you don’t need it.” These comments came from respected pilots.So…How much thrust can it lose?Especially when your not as concerned about keeping hands out of the prop as that rare time when the wing does the unexpected and a line falls near the prop.The thumper cage is new and twice pilots hooked a line at the Salton Sea. PLUS…a four stroke doesn’t shut down as fast as a two stroke so there are going to be a couple of revolutions after you hit the kill switch.

You don’t need much…

I’m not talking about some of the “hammock netting” I saw stretched over the cages of brand new quads.I’ve posted pictures of a minimal net meant to protect from Line Strike. Zip ties make it easy to get the lines tight as a tennis racket and 300 pound deep sea braid is thin and easy to tie.

Redundant Zip Ties

( one under tension)

Tweaking the Thumper

A assist with rope ratchet

— On Wed, 2/18/09, jo3jo2003 wrote:

Terry Chad,
I’ve been dialing in the “Colorado Bullet Thumper 4stroke”.Epoxy Gel and a new longer split fuel hose anchored the motor end of the throttle cable. It was moving around and preventing a true idle.The engine is max at 3800RPMidle at 1800RPMI can probably Pitch the IVOs more…BUT?Chad…how far can you pitch the IVO blades and how do you know when to stop?Can you “over warp” them and damage the system?Maybe I should learn how to measure the pitch just for the “pure research” as you put it Terry.I was glad to read about “belt Flop” on the slack side of the drive system. I’ve noticed some flop and wanted to ask how to determine correct belt tension. If I understood you right what I’m seeing is about normal.Last…Terry ….what do you think? The local Briggs & Stratton guys say I can install the high altitude carb kit in 15 minutes or less. I’m going to be launching from 8200+ MSL a few times this summer and the rest of the time will be at 5300 MSL. I’m thinking that it might be a good if I used Hi Alt jets here in Denver and the mountains and switched to the stock jets for the coastal stuff. These guys are willing to show me how to install and adjust them for the price of the labor Don’t worry….Before I start changing anything I’ll see how it does at the home field. But I wanted to run it by you.It’s just too damn cold and the best I can do is tweak the machine.
JoeO

Hi Joe, I was thinking of you today.

I think 3800rpm is fine.

Belt ‘flop’ on the slack side is normal, but I find it’s best not to watch it;); BTW, I have never lost a belt or even had the belt jump a groove. Belt tension is not something you need to worry too much about..tension it about like you would your underhood car belt. If the belt ‘flops too much to suit you, tighten it a little more, you won’t hurt anything (however it’s probably just fine right where it’s set now)

I don’t know about hi elevation carb kit, but I am curious about it..I wonder what the kit includes? Smaller jets? Different air filter?
One thing that might help is to remove all the filters from the intake shell. Please let me know what you learn about the kit.

It’s cold here too; I delivered a new unit to Indianapolis on Sunday and I demo’d it for the buyer; a 5 minute flight was plenty for me.

Terry

#233 #234 #235 Marana AZ

Three Flights …Two blown..Forgot to disengage the choke.
Strike one… I was feeling pretty good about things. The motor was starting on the first pull and I was so busy patting myself on the back that I missed the fact that I was having a hard time getting up to 6000 RPM and I also missed the way it was stuttering when I backed off the throttle. It speaks well for the bing that I could have the choke on and fly so well.
Two of the five attempted launches were aborted the first because the wing overshot and even though I was using brake and rolling forward …it would not load up. Maybe if I shortened the brake lines a bit I would have a little better control during the launch.
** NEXT FLIGHT **SEE HOW MUCH SLACK THERE IS IN THE BRAKES AT FULL TRIM AND TRIMMERS OUT. See how much pull will bring the brake lines to the point of moving the trailing edge.
The next abort was because the wing came up crooked after I had aborted stopped and brought the down it tried to pull me over in a slow roll. **NEXT TIME***TAKE A WRAP ON ONE BRAKE LINE AND HAUL IT IN.
The good launches were a mixed bag, during the highest wind I was pleased that I was able to take my time and kite the wing and taxi for awhile before I committed to the launch. The other two were not noteworthy.
All of the landings were the same, I killed the motor and flared late to bleed off speed. Nice soft touchdowns every time. It’s nice to know that I’m finally getting a little of that muscle memory that Brian Smith used to talk about. 🙂
The wheeley casters work great, but I’m going to have to practice with the trimmers at different positions because at full out the wing comes up too fast to give the buggy time to start tipping.

Tucson #230 #231 Wheeley Casters

The left side is lifting sooner than the right

Marana LZ
Higher winds gave me the excuse to try out the wheeley casters. I put the trimmers out and the wing came up quickly without pulling me back. It probably also helped that the surface was hard and smooth. One thing I noticed from viewing the video was that the left wheel lifted before the front.. I never felt like I was in danger of rolling but it is something to be aware of and possibly corrected before launching with the trimmers out. At the least I should hang the tool bag back on the left side. So while I wasn’t able to see how the casters worked on launch I did get the impression that they were touching during the run out. On landing I felt them again but no problem.

First flight was about 30 minutes, I stayed in the general vicinity of the LZ and tried to get the feel of the area. Mostly farm flying but to the west there is a river that goes north. Scott Nicoles took that route and I wish I had gone with him. I was not able to be there when he returned because Mike Levine and I had to get back for dinner with the whole family.

The second flight was a quickie, I had to abort the first launch because the left brake line was twisted and I could feel the pulley wasn’t rolling free….landing was sweet with the motor off…I flared at the last second and bled off the energy at just a couple of inches AGL.

#229 Rowdy Air Shortens Flight Simms

Salton Sea campsight 2007
Two days ago it snowed leaving 4 inches on the grass….but…

this afternoon looked beautiful. Even if the field was going little wet I thought it worth going out there to see if I had a shot at flying. I arrived at 3 (1 1/2 hours before sunset). Set-up and launched quickly.

The 3 inches of wet snow slowed the taxi and from the nice way the wing came up and settled overhead …It got me thinking that I’m a little heavy on the throttle and should practice short bursts of power to keep the speed down before committing to take-off.

Within seconds of leaving the ground I flew into some very powerful lift. and it was also clear that there was a strong breeze just above the surface. I decided to get down immediately, the only problem was that if I was going to land upwind and still be by the truck I would have to do some tricky flying. What I would have to do is fly clockwise around the trees and turn for final with enough room to avoid the wires. With all the bumps and mixing air I opted to come in fast and land downwind. There was almost no wind at the surface and even though I was technically downwind I was able to keep the wing up and taxi for over 150 feet back to the truck. Good thing too because the mud was sticky thick and I was wearing 2 inches of mud on the bottom of my boots by the time I loaded the rig back into the truck.

I think if I’d waited 30 minutes longer to launch it would have been allot better. I thought about it but decided not to because of the mud. I also wish I had launched a pilot balloon… even after landing it would have been instructive. I hope to remember this the next time the opportunity presents itself.

Before leaving the house I did change the jet to 155 and the motor started better and was more responsive. It even sounded better…deeper…more throaty.

#228 Simms

I’m thinking that the motor is running lean.

Still hard to start…

Didn’t burn much gas…

Throttle is not as responsive …

it’s not lagging just seems a little slow…

I’ve been flying a 150 jet all through the summer and fall at this altitude and higher…

The air is a little cooler but not as cool a it was this spring (during the AM flights). I’ll change to the 155 if I fly again before leaving to Tucson.

Nice flight ,Nill wind on the surface but mixing at 600 feet. Tracy the RC pilot who is considering getting into PPG was at the field. He took some shots and I hope he has something good enough that he will send me a copy. I pretty much stayed over the field and practiced a few touch and go s. I really like flying the 24 m it comes up easier and because it is loaded heaver its firm and seems more stable I going to consider selling the 26 m and trading for a 24. Marek wanted to have me try the velvet 23 but I declined. Chicken I guess. But I really should see how the smaller wing feels.