I struggled with trying to design a tailwheel dolly for years. As a 1940s vintage guy, I don't have the strength to bend over and lift the tail. However, I discovered that if I use a lifting strap wrapped under the tailcone, I can straddle the tailcone and fairly easily lift the tail up and over to plant the tailwheel on a simple platform with four coasters. With two similar platforms with four coasters and a lip that serves as a ramp that "overcenters" after the mains are rolled up the lip/ramp, and the main tires pinned in place with crossbars of 3/8" drill rod, I can pull the bird in the hangar by the wingtip. Photos on request.
My lifting strap is just a loop of mountaineers' strap with its ends tied together. Michael Stockhill Polson, MT On Sun, Oct 25, 2015 at 1:50 PM, Ian WIlliams <[email protected]> wrote: > Hi Mathys, > Thanks for your post. I am interested in your tail dolly. We have to > push our Dimona into its hangar sideways which has its own set of problems. > I have built a trolley for the main wheels but still use a temporary one > for the tail wheel so am interested in what you have in mind for the rear > end. With fuel on board and the distance of the mains from the c of g the > weight as you know is real heavy. Also needs to be a 1 man job > The one for the mains uses a couple of over centre frames and 4 big > wheels. It works real well. I'm still figuring out the tail one. Have a > steel frame with 4 smaller wheels and hope to make a clamp for the axel > bolt and a tricky over centre lifting arm. > The tow out frame is real simple.... Two PVC circular blocks with holes > on the centre clamp Over the tail wheel axel bolt and a steel frame bolted > to them to a trailer hitch. > If you are interested In our system, I can send you some pictures as I am > interested in your tail wheel dolly. > Best regards > > Ian Williams > ZK-GCB > > Sent from my iPad > > On 25/10/2015, at 8:46 pm, Mathys Kuhn <[email protected]> wrote: > > Hi Everybody > > Some final feedback on the tail wheel shimmy I have experienced: > > I have changed the tail wheel to a softer type wheel and the shimmy > stopped immediately. Although the previous tail wheel was only on the > aircraft for less than 10 hours of flying time, the aircraft stood in the > hangar for almost a year without flying. This might also have been a cause > for the shimmy. I am now in the process of manufacturing a dolly wheel for > the Dimona to take the load off the tail wheel for extended periods on the > ground. > > > > Thanks to everybody for the valuable information and help with this > problem. I certainly appreciate it > > Kind Regards > > > > *Mathys Kuhn* > > *Training Captain* > > T: 0825685614 > C: 0825685614 > F: 016 9330248 > e: [email protected] <[email protected]> > > > > *From:* [email protected] [mailto:[email protected] > <[email protected]>] *On Behalf Of *Michael Stockhill > *Sent:* 06 October 2015 03:19 AM > *To:* [email protected] > *Subject:* Re: [DOG mailing list] More on shimmy and tyres > > > > We used to have much luck in the past balancing wood props by adding > another coat of paint or more to the light end of the prop. > > > > > > MLS > > > > On Mon, Oct 5, 2015 at 4:33 PM, wallace barnes < > [email protected]> wrote: > > Hi All > Just putting in my little bit. To balance tail wheel and dynamic > balance of prop go to a Tyre place and get a card of stick on weights as > used on mag wheels there are a range of weights on each card. We have added > 10 gms to our new prop and the results are amazing. > cheers Wally > > > > On 5/10/2015 3:13 PM, Ian Mc Phee wrote: > > Rob > Thanks for that. I would never have thought of balancing tailwheel. I use > square Mc ready tyres 6pr 250x4 as am sick of the bunnings ones from China. > > I can say with PIK20E prop it really helps as with falke fixed pitch prop > but even better do a dynamic balance on the prop. > > Ian Mc Phee > 0428847642 > Box 657 Byron Bay NSW 2481 > AUSTRALIA > > On 5 Oct 2015 4:10 pm, "Rob Thompson" <[email protected]> wrote: > > Don't forget that if your tail wheel is out of balance it will be much > more prone to shimmy. > > A static balance can be acheived quite easily. > > A tiny bit of lead sheet flashing cut out to size and glued, screwed or > doubled sided taped in place will solve the problem. > > Just support the well oiled shaft and see which side of the wheel rotates > to the bottom. > > > cheers > Rob > > Rob Thompson > 0429 493828 > *Please note that my new email address is [email protected] > <[email protected]>* > > ------------------------------ > > From: [email protected] > To: [email protected] > Date: Mon, 5 Oct 2015 11:21:28 +1100 > Subject: [DOG mailing list] Shimmy and tyres > > I have suspected for a while now that the square profile tail wheel tyres > are less prone to shimmy than the round ones. > > Yesterday we changed to a round profile and for the first time in ages got > a bit of shimmy on bitumen on the take off roll. Landed on grass but I will > test the theory more sometime soon. > > Rob > > Rob Thompson > 0429 493828 > > > ------------------------------ > > Date: Mon, 5 Oct 2015 11:09:19 +1100 > From: [email protected] > To: [email protected] > Subject: Re: [DOG mailing list] H36 Tail wheels > > I found out my previous message didn't get through because of file size. > Here it is again. > > Michael is on the right track. The vertical shaft on any castor wheel has > to be exactly vertical. > > What happens with the Dimona h36 is that shaft gets bent slightly due to > potholes etc. and from then on you have shimmy. The bend can be barely > visible. > > The more the bend the more the excitement. I have had both the straight > tailwheel and the damped one and the only difference is in height. > > I have seen a " repaired " one that was made stronger and that stuffed the > C of G. The one with the damper bracket weighs 725 grams. > > > > A new part definitely fixes the problem. > > Regards, > > John. > > > > On 3 October 2015 at 00:08, Michael Stockhill <[email protected]> wrote: > > I don't have the W&B info on my friend's H-36 here, but I do remember > weighing it and finding the numbers way aft, somewhere on either side of > the aft limits when flown solo. My own H-36 is fine. I can't account for > the difference, suspecting perhaps an undocumented heavy repair, and the > very lavish heavy beautiful refinish that was done. It has been a few > years, but I did some calculations for adding a weight in the nose, but > with the relatively short arm it was impractical. > > > > Life is great, > > > > > > MLS > > > > On Thu, Oct 1, 2015 at 8:19 PM, Nigel Baker <[email protected]> > wrote: > > I am surprised by your comment on them being tail heavy. > > I have weighed 4 different H36 aircraft and they all came in close to each > other in C of G. > > See attached for my own aircraft. > > Cheers. > > Nige. > > > > > > *From:* Michael Stockhill <[email protected]> > > *Sent:* Friday, October 02, 2015 11:04 AM > > *To:* [email protected] > > *Subject:* Re: [DOG mailing list] H36 Tail wheels > > > > My friend tried a later-model tailwheel fork with the rubber dampers on > his H-36. I wasn't present, but recall that it is far heavier and put an > already tail heavy bird way out of CG limits. There were other issues that > prevented retrofit, if I remember correctly. > > > > > > MLS > > > > On Thu, Oct 1, 2015 at 4:56 PM, Rob Thompson <[email protected]> wrote: > > The early H36 models had a straight un-damped tail wheel fork which, due > the wheels being forward of the centre of gravity and the heavy tail weight > can induce some quite nasty oscillations. > > As a result of this Hoffman later introduced a new tail wheel which has > shock absorbing rubbers. This reduces dramatically the oscillations but is > more prone to shimmy. > > If the tail wheel cables are too tight the steering becomes VERY > responsive to the slightest pedal movement. If the cables are too loose you > get shimmy. Takes a bit of experience to know when it is just right. Real > pain when you have to take the tank out each time to get it right! > > > > Rob Thompson > 0429 493828 > *Please note that my new email address is [email protected] > <[email protected]>* > > ------------------------------ > > From: [email protected] > To: [email protected] > Date: Thu, 1 Oct 2015 21:09:03 +0200 > Subject: Re: [DOG mailing list] Morning Glory Cloud Documentary > > Most interesting and helpful thanks Michael. My Dimona is also a bit of a > beast on the ground compared to other taildragger aircraft I have flown. I > will keep you pisted. Thanks for taking the time to write the detail. > > Regards. > > Thys > > > > > > > > Sent from my Samsung Galaxy smartphone. > > > > -------- Original message -------- > From: Michael Stockhill <[email protected]> > Date: 01/10/2015 20:57 (GMT+02:00) > To: [email protected] > Subject: Re: [DOG mailing list] Morning Glory Cloud Documentary > > Hi, Mathys, > > > > I own an H-36 and also maintain one belonging to a friend. Between the > two of us, we have had some interesting tailwheel issues. My bird was the > scariest tailwheel aircraft I had flown ( about 800 hours in various Super > Cubs, Cessna 180's and 185's and DH Beavers, etc.). If you breathed on the > rudder pedals during takeoff or landing when the tailwheel was on the > ground, it would threaten to leave the runway, and on two or three > occasions I suffered PIO (pilot-induced oscillations) that shook my teeth. > What I finally discovered was a logbook reference to a tailwheel fork > repair. The fork was rewelded at that time with absolutely no trailing > rake. We rebuilt it with 7 degrees aft rake and that demon was tamed. It > now actually reminds me of a normally operating aircraft. > > > > In the case of my friend's Dimona, most landings resulted in scary > tailwheel shimmy--I thought it would take off the tailboom. He mitigated > this at first by making wheel landings and holding the tail off as long as > he could. On the couple times I experienced it, I braked as much and as > soon as possible to get slowed down. We tried various tailwheel tire > pressures and checked balance, etc.. It has been a while, so my > recollection is a bit vague, but what I did discover by looking at the > tailwheel fork while installed, the shoulder of the weldment where the > vertical shaft enters the lower flanged spacer was not parallel with the > face of that spacer. Upon disassembly we were able to discern some bending > of the shaft at that point (the shoulder of the weldment and the tailwheel > vertical shaft). We had a whiz of a machinist fabricate a new shaft and > other parts of the tailwheel fork. I test flew it afterwards and it was a > different airplane. Rudder cables were also replaced at a later date. > > > > Hope some of that is of help to you. > > > > Michael Stockhill > > Polson, Montana, USA > > > > On Wed, Sep 30, 2015 at 3:40 AM, Mathys Kuhn <[email protected]> > wrote: > > Hi Everybody > I operate a mid 80’s model Hoffma Dimona in South Africa. Lately I started > experiencing a significant tailwheel shimmy at low speed after landing on a > tar runway. Has anybody ever experienced something similar? ANY ADVICE? > Many Thanks > > > *Mathys Kuhn* > > *Training Captain* > T: 0825685614 > C: 0825685614 > F: 016 9330248 > e: <[email protected]>[email protected] > > > > *From:* [email protected] [mailto:[email protected]] *On > Behalf Of *Ian Williams > *Sent:* 23 September 2015 10:56 AM > *To:* [email protected] > *Subject:* Re: [DOG mailing list] Morning Glory Cloud Documentary > > > > Apparently only able to be viewed in Australia. > > Sent from my iPhone > > > On 23/09/2015, at 13:05, Rob Thompson <[email protected]> wrote: > > G'day All, > > For those of you who missed it, the Morning Glory Cloud Documentary is on > SBS "Catch Up" > > > http://www.sbs.com.au/ondemand/video/521484355510/secrets-of-a-strange-cloud > > cheers > > Rob > > Rob Thompson > 0429 493828 > > P Please consider the environment before printing this e-mail. > ------------------------------ > > > *Attention: * > Please note: This email and its content are subject to the disclaimer as > displayed at the following link http://www.comair.co.za/disclaimer.html. > Should you not have Web access, send an email to [email protected] > and a copy will be sent to you. > > ------------------------------ > > > > > > > > > > > --------------------------------------------------------------------- > You are subscribed to the Dimona Owners Group mailing list. > To unsubscribe, send email to: [email protected] > > > > > > > --------------------------------------------------------------------- You > are subscribed to the Dimona Owners Group mailing list. To unsubscribe, > send email to: [email protected] > > > > > > P Please consider the environment before printing this e-mail. > > ------------------------------ > > *Attention: * > Please note: This email and its content are subject to the disclaimer as > displayed at the following link http://www.comair.co.za/disclaimer.html. > Should you not have Web access, send an email to [email protected] > and a copy will be sent to you. > > ------------------------------ > >
